PROCEEDINGS OF THE BRITISH PHARMACOLOGICAL SOCIETY CLINICAL PHARMACOLOGY SECTION

19-21 December 1988

INSTITUTE OF EDUCATION (KING'S COLLEGE LONDON)

For oral communications with more than one author, an asterisk (*) denotes the one who presented the work. 644P Proceedings of the BPS, 19-21 December 1988

COMMUNICATIONS The disposition of amodiaquine in Zambians 10 mg kg-', followed by 5 mg kg-' 6, 24 and with malaria 48 h thereafter. Blood was centrifuged (2000 g, 10 min) within 10 min. AQ and AQm were P. A. WINSTANLEY*, 0. 0. SIMOOYA, determined by the method of Winstanley et al. G. EDWARDS, M. L'E. ORME, J. M. KOFI EKUE (1987); in the case of RBC samples the method & A. M. BRECKENRIDGE was modified by the use of the extraction pro- Department of Pharmacology and Therapeutics, The cess of Pussard et al. (1986). University of Liverpool, UK; Department of Clinical Clinical cure was achieved in all patients. Pharmacology, Tropical Diseases Research Centre, Parasite numbers were 5.33 ± 1.6, 6.63 ± 1.95, Ndola, Zambia 0.26 ± 0.07 and 0.07 ± 0.05 x 103 mm-3 (mean ± s.e. mean) on days 1-4 respectively. Plasma Amodiaquine (AQ), although rarely used for profiles of AQ and AQm were similar to those malaria prophylaxis because of adverse effects, obtained from healthy British subjects, with remains in use for the treatment of chloroquine AQ achieving low concentrations; the apparent [CQ]-resistant falciparum malaria; the drug's t½l, of AQ was 3.7 ± 0.6 h in the five patients serious adverse effects have not been reported in whom this parameter could be determined. in malaria patients. AQ kinetics have been Peak plasma concentrations of AQm, after each studied primarily in healthy subjects (Winstanley dose of AQ were 161 ± 19, 146 ± 16, 194 ± 17 et al., 1987) where the red cell (RBC): plasma and 251 ± 29 ng ml-'. The RBC: plasma con- concentration ratio for the active metabolite centration ratio of AQm differed from that seen desethylamodiaquine (AQm) is 3:1. Malaria per- in health, and was 0.9:1 at the start, and rose turbs the disposition of CQ (Adelusi et al., 1982), in linear fashion over time (r = 0.837; P S 0.01) causing an elevation of the drug's RBC: plasma to 2.8:1 by the end of the study (P < 0.05). concentration ratio, which falls as parasitaemia These data show further differences between is cleared. The purpose of the present study was the pharmacology of AQ and CQ, showing a to investigate the effect of malaria infection on rise to occur in the RBC: plasma ratio for AQm the disposition of AQ. Patients presenting to as parasitaemia was cleared. The clinical impor- Ndola Central Hospital with clinical malaria tance of the findings in particular their relevance gave written informed consent (n = 14; ages to the apparently low prevalence of agranulo- 16-55 years). Blood films were examined daily cytosis and hepatitis in malaria patients treated for malaria parasites. All patients received four with AQ, remains to be determined. doses of oral AQ (Camoquin, Parke-Davis):

Adelusi, S. et al. (1982). Br. J. clin. Pharmac., 14, Winstanley, P. et al. (1987). Br. J. clin. Pharmac., 483. 23, 1. Pussard, E. et al. (1986). J. Chromatogr., 374, 111.

Differential immunoinhibition of human treated rats, we have demonstrated differential liver oestradiol and ethinyloestradiol oestrogen 2-hydroxylase activity towards the 2-hydroxylase endogenous oestrogen oestradiol (E2) and the contraceptive steroid ethinyloestradiol (EE2) S. E. BALL'*, D. J. BACK1, L. FORRESTER2, C. (Ball et al., 1988a). Using polyclonal rabbit R. WOLF2 & M. L'E. ORME1 anti-rat antibodies raised against these purified 'Department of Pharmacology, University of Liver- isozymes, we have attempted to characterise pool and I.C.R.F., 2Department of Biochemistry, potential structural and functional homologous University of Edinburgh, Edinburgh forms of human liver cytochromes. Human liver microsomes were prepared by In previous studies using reconstituted rat puri- differential centrifugation from sixteen human fied cytochrome P450 isozymes from phenobar- livers obtained from renal transplant donors. E2 bitone (PB) and 3-methylcholanthrene (3-MC) and EE2 2-hydroxylase activity was determined Proceedings of the BPS, 19-21 December 1988 645P by performing microsomal incubations as and EE2 (0.36-0.93 nmol min-1 nmol-1 P-450) previously described (Ball et al., 1988b). Micro- 2-hydroxylase activity which by Spearman somal immunoinhibition assays were performed ranked correlation analysis were poorly cor- by pre-incubating microsomal protein (0.5 mg) related (r = 0.34, P 3 0.05). XPBla had the from six different livers with IgG (2.5 mg of greatest inhibitory activity towards EE2 and aPBla, otPB3a, aPB2c, OtMCla or OcMClb) aMClb towards E2. cxPB3a, otPB2c, and for 15-20 min at room temperature. Immuno- OMCla had low inhibitory potency. Table 1 inhibition assays contained preincubated protein shows the antibody inhibitory potency of aPBla (0.5 mg), E2 or EE2 (25 RM), ascorbic acid and aMClb towards the two substrates for six (1 mM), NADPH (0.6 mM) and 1/15 M potassium livers. phosphate buffer (pH 7.4; 3 ml). Incubation The poor correlation between E2 and EE2 was at 370 C for 45 min followed by h.p.l.c. 2-hydroxylase activity and the differential metabolite quantification using a modified immunoinhibition data suggest that in man method of Purba et al. (1986). different isozymes may be at least partially re- There was a three fold variability in the con- sponsible for the 2-hydroxylation of synthetic trol E2 (0.62-2.08 nmol min-1 nmol-1 P-450) and endogenous oestrogens.

Table 1 % uninhibited activity of E2 2-hydroxylase EE2 2-hydroxylase Liver OtMCJb aPBia ttMClb atPBia 1 82 75 88 65 2 26 60 94 45 3 55 77 90 39 4 21 76 97 38 5 50 71 88 11 6 39 51 79 49 (values are the average of two determinations).

Ball, S. E. et al. (1988a). Br. J. Pharmac., 94, 449P. Purba, H. S. et al. (1986). J. Steroid Biochem., 24, Ball, S. E. et al. (1988b). Br. J. clin. Pharmac., 25, 1091. 643P.

Prediction of steady-state phenobarbitone 7 weeks, PB 2 mg daily for 28 days. Blood levels from measurements after a single dose samples were taken at suitable intervals between 1 h and 336 h following the single dose and pre- S. KUMAR*, T. PULLAR, H. CHRYSTYN', dose and over 240 h following the last of the S. PEAKER & M. FEELY repeated doses. Plasma PB concentrations, Clinical Pharmacology Unit, The General Infirmary, measured using high-performance liquid chro- Leeds, LS1 3EX and 'School of Pharmacy, Univer- matography (Gill et al., 1981; Feely et al., 1987), sity of Bradford, Bradford BD7 lDP were used to determine single dose and steady state pharmacokinetic parameters. There were Low-dose phenobarbitone (PB) can be used no significant differences between either clear- as a pharmacological indicator of compliance ance (paired t-test; P = 0.34) or half-life (paired (Feely et al., 1987). With a view to improving t-test; P = 0.56) following the single dose and the accuracy of this technique we have attempted at steady state (Table 1). to predict steady state PB concentrations for Predictions of steady state peak and trough individual subjects from measurements obtained PB levels were carried out using Bayesian an- after a single dose. Ten healthy volunteers (aged alysis from single plasma PB measurements at 23 to 36 years; 8M, 2F) were each given PB 24, 48, 72 and 96 h post single dose. For peak 30 mg as a single dose and, after an interval of level predictions (mean ± s.d. measured = 383.7 646P Proceedings of the BPS, 19-21 December 1988 ± 60.4 ng ml-'), the later the sample was taken for trough level predictions were 18.9 and 37.2 the more precise and less biased were the pre- ng ml-'. dictions. For trough level predictions (mean + These results suggest that, using Bayesian s.d. measured = 308.5 ± 46.1 ng ml-1, the later analysis, steady state PB levels may be pre- the sample was taken the more precise but more dicted from measurement of plasma PB con- biased were the predictions. Mean prediction centrations at an appropriate interval after a error and root mean squared error of peak level single dose. This may allow a more accurate predictions using the sample drawn 96 h post identification of various degree of incomplete single dose in Bayesian analysis were -8.8 and compliance with prescribed treatment. 34.2 ng ml-n respectively. Corresponding values

Table 1 Plasma clearance (CL) and half-life (t½h) of PB and steady state peak PB levels (predictions from 96 h post single dose measurement) Single dose Steady state Steady state peak PB levels CL t½ CL t½ Measured Predicted Subject (ml h1 kg-') (h) (ml h- kg-') (h) (ng ml-') (ng ml-') 1 3.17 105 3.27 138 403 376 2 5.10 74 4.83 52 299 276 3 2.81 132 2.87 127 416 406 4 4.21 95 4.35 105 266 264 5 2.31 138 2.57 145 411 395 6 4.26 95 4.23 92 467 410 7 2.86 117 3.06 138 415 394 8 3.86 105 3.70 113 354 320 9 2.76 127 2.77 127 411 467 10 3.07 117 3.31 105 395 441

Feely, M. et al. (1987). Br. J. clin. Pharmac., 24, 77. Gill, R. et al. (1981). J. Chromatogr., 226, 117.

Debrisoquine metabolic phenotype in linkage with a flanking gene critical to the car- patients with bronchogenic carcinoma cinogenic process. In the present study the debrisoquine metabolic phenotype was deter- A. R. BOOBIS*, C. J. SPEIRS, S. MURRAY, mined in a population of lung cancer patients in A. F. B. MABADEJE & D. S. DAVIES an effort to confirm the findings of Ayesh et al. Department of Clinical Pharmacology, Royal Post- (1984). graduate Medical School, Ducane Road, London Eighty-two patients with histologically or W12 ONN cytologically proven carcinoma of the lung gave their written informed consent to participate in Bronchogenic carcinoma, due largely to ciga- the study, which had local Research Ethics rette smoking, is the major neoplastic disease Committee permission. Subjects received 1 mg in males in developed countries. In a study of debrisoquine orally after which all urine was such patients, Ayesh et al. (1984) showed (1) collected for 8 h. Debrisoquine and 4-hydroxy- a considerable under-representation of poor debrisoquine were determined by combined metabolisers (PM) of debrisoquine, and (2) a capillary column gas chromatography negative significant decrease in metabolic ratio (molar ion chemical ionisation mass spectrometry. ratio of debrisoquine to 4-hydroxydebrisoquine Substitution of 1 mg for the normal test dose of in urine; MR) in extensive metabolisers (EM), 10 mg debrisoquine had been shown previously compared with control.subjects. The explana- not to affect the MR (Speirs et al., 1986). tion for this is not clear, but activation of pro- Patients ranged in age from 46 to 86 years carcinogenic compounds in cigarette smoke by (median 64 years). The male:female ratio was the form of cytochrome P450 deficient in the 60:22. Most patients were Caucasian (73), with PM phenotype is unlikely. One possibility is a few West Indian and Asian. With one excep- Proceedings of the BPS, 19-21 December 1988 647P tion, all of the patients were, or had been, although the number of subjects with MR < 1.0 cigarette smokers. The majority of patients had was very similar to that in most previous control squamous cell carcinoma (59%), with some Oat groups and in the cancer patients studied by cell (17%) and adenocarcinoma (11%). The log Ayesh et al. (1984), this was significantly greater MR was distributed bimodally, with an antimode than in the control patients in the latter study at 1.15 (MR = 14). Eight of the subjects were (P < 0.01). Thus, it was not possible to confirm classified as PM phenotype. The,median value an association between debrisoquine metabolic for the MR in the EM subjects was 0.868, and phenotype and bronchogenic carcinoma. Nor 59% of subjects had a MR of < 1.0. There were was it possible to confirm a shift in MR to lower 66 Caucasian subjects who had tumours that values in lung cancer patients. Rather, it appears were not adenocarcinoma. Within this group, that there was a shift in the MR to higher values comparable with that studied by Ayesh et al. in the control group in the earlier study (Ayesh (1984), MR was also distributed bimodally, et al., 1984). The reason for the difference in with the same antimode as in the entire patient the proportion of PM subjects in the two groups group. There were six PM subjects, 37 had MR of cancer patients is unclear. However, the < 1.0 and the median value for the MR in the results of the present study are in broad agree- EM subjects was 0.868. Thus, the distribution ment with those of Roots et al. (1988). It may of MR in this sub-group was virtually identical be that subtle factors in patient selection under- to that in the parent population. lie the differences amongst these studies, but The frequency of the PM phenotype in the whatever the explanation it is apparent that the present patient population did not differ from value of the debrisoquine phenotype as a marker that in control subjects (Price Evans et al., of susceptibility to lung cancer, certainly in a 1980; Ayesh et al., 1984; Steiner et al., 1985). clinical context, is low in the population at large. However, this was very significantly greater than in the lung cancer patients studied by Ayesh This work was supported by grants from the Medical et al. (1984) (z = 3.38, P < 0.001). In addition, Research Council and the Wellcome Trust. Ayesh, R. et al. (1984). Nature, 312, 169. Speirs, C. J. et al. (1986). Br. J. clin. Pharmac., 22, Price Evans, D. A. et al. (1980). J. med. Genet., 17, 739. 102. Steiner, E. et al. (1985). Clin. Pharmac. Ther., 38, Roots, I. et al. (1988). Abst. IInd ISSX Mtg, Kobe, 394. Japan, p. 110.

Acute cognitive effects of moclobemide and of the two drugs were compared in the elderly, trazodone, alone and in combination with both with and without ethanol (ETH). alcohol, in the elderly Twenty-seven volunteers aged between 60 and 75 years entered the study. One withdrew K. A. WESNES*, P. M. SIMPSON, due to personal reasons and two due to cardio- L. CHRISTMAS, G. R. McCLELLAND' & vascular symptoms after TRZ. All subjects com- I. M. JOINER2 pleted four training sessions on a test battery, Cognitive Drug Research, Reading, RG1 4RB, 'Roche and were then randomly allocated to two groups, Products, Welwyn Garden City, AL7 3AY and 2The one who received ETH (0.5 g kg-') and the Surgery, Middle Hill, Aldershot other, placebo-ethanol (PL-ETH), in addition to the four study treatments given a week apart, Moclobemide (MOC) is a novel reversible (placebo (PL), TRZ 100 mg, MOC 100 mg, MAO-A inhibitor and in a scopolamine model MOC 300 mg). At pre-dose and 1, 2, 3, 4 and of impaired cognition, was shown to restore 6 h post-dose the subjects performed the test mental efficiency in young volunteers (Wesnes battery, which consisted, primarily, of a range et al., 1988). Trazodone (TRZ), is primarily a of computerized cognitive tasks sensitive to serotonin re-uptake blocker, which has shown drug effects in the elderly, as described by sedation, and impaired tracking in the elderly, Wesnes et al. (1987). ETH/PL-ETH was admin- while not affecting performance on many other istered 1.5 h post-dose. tasks (Branconnier & Cole, 1981; Burns et al., The 24 subjects who completed the study 1986). In the present study the cognitive effects were evenly divided between the two groups. 648P Proceedings of the BPS, 19-21 December 1988 The data were first analysed using a non-para- doses was significantly superior to TRZ. TRZ metric global procedure in which each primary generally impaired simple and choice reaction measure was ranked over the four treatments time, number vigilance and body sway. Further, for each subject, these ranks were then summed in the ETH group, TRZ impaired memory for all measures, separately for the two groups. scanning, verbal recognition, and subjective Wilcoxon testing revealed TRZ to be signifi- alertness. MOC only consistently impaired per- cantly inferior to PL at 2, 3, 4 and 6 h in both formance on one task, number vigilance, while groups. The magnitude of this effect is seen in both doses improved verbal recognition and the the mean rankings (1 = poorest performance to 300 mg dose improved memory scanning. 4 = best) in both the PL-ETH group (2 h PL = This study indicated that when sensitive com- 3 TRZ = 1.71; 3 h PL = 3 TRZ = 1.29; 4 h PL puterized techniques are employed, trazodone = 2.83 TRZ = 1.46; 6 h PL = 3.33 TRZ = 100 mg produces a wider range of cognitive 1.58) and the ETH group (2 h PL = 3.42 TRZ impairments in the elderly than has been pre- = 1.5; 3 h PL = 3.13 TRZ = 1.33; 4 h PL = viously found, while moclobemide produces 3.04 TRZ = 1.71; 6 h PL = 3.29 TRZ = 1.5). few impairments and shows some evidence of MOC was only inferior to PL at the 300 mg improving memory. The impairments produced dose in the PL-ETH group at 6 h (PL = 3.33 by trazodone and ethanol appeared to be addi- MOC = 2.54), although this dose was still tive, while there was no such effect with either superior to TRZ at this time, indeed in both dose of moclobemide. groups from 2 to 6 h one or both of the MOC

Branconnier, R. J. & Cole, J. 0. (1981). J. clin. Wesnes, K. et al. (1988). Abstract of British Associa- Psychopharmac., 1, 82S. tion for Psychopharmacology, July Meeting, Burns, M. et al. (1986). J. clin. Psychiat., 47, 252. p. 32. Wesnes, K. et al. (1987). Hum. Psychopharmac., 2, 159.

adaptation night and the data from the second The effect of lithium on slow wave sleep of each pair was analysed. in man The sleep EEGs were recorded in the sub- jects' own homes using the Oxford Medilog 9000 R. A. SOLOMON*, K. J. FRISTON, 9 channel ambulatory cassette recorder and the A. L. SHARPLEY & P. J. COWEN records were analysed using the Medilog auto- University Department of Psychiatry and MRC Unit matic sleep stager (SS90III). of Clinical Pharmacology, Littlemore Hospital, Before lithium treatment the mean SWS for Oxford OX4 4XN the 10 subjects was 68 ± 10.1 min and this was increased to 86 ± 9.0 min on the seventh night Recent studies in rodents suggest that lithium of lithium treatment (P = 0.012). This was an reduces behavioural responses mediated by overall increase of 27%. post-synaptic 5-hydroxytryptamine2 (5-HT2) In addition, after lithium treatment there was receptors (Goodwin et al., 1986). In humans an increase in the amount of wake after sleep on- selective 5-HT2 receptor antagonists increase set from 26.4 ± 5.2 min to 46.4 ± 11.8 min (P the amount of slow wave sleep (SWS) in the = 0.016) and a reduction in percentage of actual sleep EEG (Idzikowski et al., 1986). We there- sleep time from 93.4 ± 1.0% to 89.2 ± 2.4% fore predicted that if lithium decreased brain (P = 0.019). REM sleep was also reduced from 5-HT2 receptor function in humans it should 106 ± 5.4 min to 82.5 ± 8.9 min (P = 0.046). increase SWS. The ability of lithium to increase SWS is con- Ten normal male subjects, age range 25-37 sistent with a reduction in brain 5-HT2 receptor years, took 1 g of lithium carbonate (Priadel) function; however at present we cannot exclude for 7 days. The plasma lithium levels ranged the possibility that lithium might produce changes from 0.55-1.16 mmol F-' 12 h after the final in SWS through mechanisms other than altera- dose of lithium. Sleep EEGs were recorded on tions in 5-HT neurotransmission. two pairs of consecutive nights; the first pair This study also suggests that home EEG in the week before lithium treatment and the recording with automatic sleep stage analysis second pair on nights 6 and 7 of lithium treat- provides a useful and acceptable method of ment. The first of each pair was used as an assessing the effects of drugs on SWS. Proceedings of the BPS, 19-21 December 1988 649P

Goodwin, G. M. et al. (1986). Psychopharmacology, Idzikowski, C. et al. (1986). Brain Res., 378, 164. 90, 482.

a2-adrenoceptor antagonism increases toxymelatonin (aMT6s), the major metabolite nocturnal plasma melatonin in man of melatonin (Aldhous & Arendt, 1988). Eight normal male volunteers were tested P. M. GRASBY*, E. J. BEGG, S. E. GARTSIDE & twice, receiving on one occasion, idazoxan 40 P. J. COWEN mg orally and on the other placebo. The tests University Department of Psychiatry and MRC Unit took place over two evenings separated by an of Clinical Pharmacology, Littlemore Hospital, Oxford interval of 1 week. Subjects were randomly and OX4 4XN blindly assigned to receive either idazoxan or placebo first. An indwelling venous cannula The nocturnal increase in plasma melatonin in was inserted at 19.30 h and after baseline humans results from stimulation of pineal post- sampling, idazoxan or placebo was given at synaptic P1-adrenoceptors by noradrenaline 20.00 h. Further blood samples were taken released from prejunctional sympathetic ter- every 30 min until 24.00 h. Testing took place minals (Cowen et al., 1983). Evidence from the under dim light conditions (500 lux). Urine was rat suggests that pineal prejunctional terminals collected from 20.00 h to 11.00 h the next day possess a2-adrenoceptors, stimulation of which for estimation of aMT6s. Plasma melatonin and with the a2-adrenoceptor agonist, clonidine, aMT6s were measured by radioimmunoassay reduces noradrenaline release whilst a2- (Fraser et al., 1983; Aldhous & Arendt, 1988). adrenoceptor blockade with yohimbine increases The increase in plasma melatonin was calcu- noradrenaline release (Pelayo et al., 1977). The lated as the area under the curve using the functional importance of these c2-adrenoceptors trapezoid method. in human melatonin production is unclear. Lewy Administration of idazoxan, 40 mg, produced et al. (1986) reported that intravenous clonidine a small but significant increase in plasma mela- reduced night time plasma melatonin, but using tonin and urinary 6-sulphatoxymelatonin a lower dose of clonidine, we were unable to (Table 1). This dose of idazaxon attenuates the confirm this finding (Grasby & Cowen, 1988). sedative effects of intravenous clonidine in To resolve this issue we studied the effect of the human volunteers indicating effective a2- selective a2-adrenoceptor antagonist, idazoxan, adrenoceptor antagonism (Clifford & Price, on nocturnal melatonin secretion, predicting 1984). Our findings suggest a functional role for that idazoxan administration should increase a2-adrenoceptors in melatonin production. nocturnal plasma melatonin if a2-adrenoceptors have a significant functional role in melatonin PMG is a MRC Clinical Training Fellow. We thank production. We also measured the effect of Reckitt & Colman for supplying idazoxan and idazoxan on the urinary excretion of 6-sulpha- financial assistance.

Table 1 Effect of idazoxan (40 mg) on plasma melatonin and urinary aMT6s Plasma melatonin (AUC) (pg ml-' h) Total aMT6 (,ug (20.00-11.00 h) Placebo Idazoxan Placebo Idazoxan Mean ± s.e. mean 53 ± 13 78 ± 19* 6.3 ± 1.1 7.5 ± 1.2* (n = 8) *significantly different from placebo P < 0.05 Student's t-test (paired)

Aldhous, M. & Arendt, J. (1988). Ann. clin. Bio- Fraser, S. et al. (1983). Clin. Chem., 29, 396-397. chem., 25, 298. Grasby, P. M. & Cowen, P. J. (1988). Hum. Psycho- Clifford, J. M. & Price, M. (1984). Br. J. clin. pharmac., 3, 43. Pharmac., 17, 602P. Lewy, A. J. et al. (1986). J. Pharm. Pharmac., 38, Cowen, P. J. et al. (1983). Br. J. clin. Pharmac., 15, 555. 579. Pelayo, F. et al. (1977). Eur. J. Pharmac., 45, 317. 650P Proceedings of the BPS, 19-21 December 1988

Platelet oc2-adrenoceptor binding a2-adrenoceptor binding by saturation binding differentiates benign essential tremor and of [3H]-UK 14,304 (0.2-10.5 nM) to platelet Parkinson's disease membranes. Non-specific binding was defined by 10-5 M phentolamine. Equilibrium dissocia- JULIA THILO, K. M. LAWRENCE, tion constants (KD) and the maximum number A. E. THEODOROU*, R. W. HORTON, of binding sites (Bmax) were determined by non- N. BLACKWOOD', M. GREENWOOD', linear regression analysis. A. HOWICK', L. FINDLEY2 & P. N. LEIGH' The number of [3H]-yohimbine binding sites Department of Pharmacology and Clinical Pharma- in BET patients was significantly lower than PD cology and 'Department of Medicine I (Neurology), patients or controls (Table 1). The number of St George's Hospital Medical School, London SW17 [3H]-UK 14,304 binding sites in BET patients and 2The National Hospital, Queen Square, London did not differ from controls but was significantly WC1 lower than PD patients. The KD of both ligands did not differ significantly between the groups. Benign essential tremor (BET) is a common In contrast to Berlan et al. (1986), a2-adreno- form of postural and action tremor. The patho- ceptor binding did not differ significantly be- physiology is unknown, although a- and 13- tween PD patients and controls. The age of adrenoceptor mechanisms have been implicated BET patients (57.2 ± 3.6 years) did not differ in mediating the beneficial effects of drugs (Mai significantly from controls (59.6 ± 3.1 years), & Olson, 1981; Leigh et al., 1983). It has been but PD patients (70 ± 2.5 years) were signifi- suggested that patients with BET have a higher cantly older than BET patients and controls. It than normal risk of developing Parkinson's is unlikely that differences in age are an impor- disease (PD, Geraghty et al., 1984) although tant factor since we found no significant cor- this is controversial (Cleeves et al., 1988). Since relation between age and a2-adrenoceptor platelet a2-adrenoceptor binding has been re- binding in the individual groups or when the ported to be reduced in untreated PD patients groups were combined. Thus the lower platelet (Berlan et al., 1986), we have compared platelet a2-adrenoceptor binding in BET compared with a2-adrenoceptors in drug-free patients with PD patients suggests a different, rather than a PD (5M, 2F), BET (9M, 14F) and healthy con- common, pathophysiology of these movement trols (5M, 14F). disorders. Total a2-adrenoceptor binding sites were determined by saturation binding of [3H]- We thank the Nuffield Foundation and the Parkinson's yohimbine (0.2-28 nM) and high affinity agonist Disease Society for financial support.

Table 1 a2-adrenoceptor binding in patients with PD or BET and controls [3H]-yohimbine [3H]-UK 14,304 KD Bmax KD Bmax Controls (n = 19) 1.77 ± 0.44 238 ± 21 0.78 ± 0.08 159 ± 12 BET (n = 19-23) 1.12 ± 0.09 186 ± 11*t 0.82 ± 0.09 139 ± 10t PD (n = 7) 1.17±0.12 300 ± 26 0.80±0.14 194 ± 11 Values are means ± s.e. mean KD = nm, Bmax = fmol mg-1 protein. *P < 0.05 compared with controls, t P < 0.01 compared with PD.

Berlan, M. et al. (1986). Br. J. clin. Pharmac., 21, Leigh, P. N. et al. (1983). J. Neurol. Neurosurgery 618P. Psychiat., 46, 710. Cleeves, L. et al. (1988). Ann. Neurol., 24, 23. Mai, J. & Olson, R. B. (1981). J. Neurol. Neuro- Geraghty, J. J. et al. (1984). Ann. Neurol., 17, 329. surgery Psychiat., 44, 1171. Proceedings of the BPS, 19-21 December 1988 651P The effects of ICI 118,551 in acute anxiety Anxiety Scale (HAS); and not have used psycho- states tropic drugs, other than a few doses of benzo- diazepine, in the previous 2 months. Evidence S. J. COOPER*, A. GILLILAND', C. KELLY & of severe personality disorder, alcoholism, S. McGILLOWAY pregnancy or significant physical illness were Department of Mental Health and 'Department of exclusion factors. Following initial assessment General Practice, The Queen's University of Belfast, patients' anxiety symptoms were rated on further Belfast BT9 7BL visits using the HAS and a self-rating scale. All patients received placebo medication for the ,B-adrenoceptor antagonists have been used in first week on a single blind basis. If they still the management of anxiety symptoms since the fulfilled the entrance criteria they then entered initial clinical trial of Granville-Grossman & a 4 week double-blind treatment phase, ran- Turner (1966). The mechanism of action is domly allocated to either placebo, diazepam thought to be peripheral (Bonn & Turner, 1972) 2 mg three times daily or ICI 118,551 50 mg but it is not clear whether 13 or 12 effects are three times daily. most important. ICI 118,551 is a fairly selective We assessed 86 patients but only 51 eventually 032-adrenoceptor antagonist in doses up to reached the 4 week double-blind study period. about 50 mg three times daily (Arnold et al., Dropouts were roughly equal from each group: 1985; Jefferson et al., 1987). In other respects placebo = 7, diazepam = 4, ICI 118,551 = 5. it is similar to propranolol. We report a study There was no evidence of any difference be- of its effects in acute anxiety states. tween the treatments (Kruskal-Wallis) though Patients were referred to the study from a all treatments produced statistically significant group of four G.P. practices and were thus not improvement over 4 weeks (Friedman analysis the more chronic type of anxiety patient seen in of variance; Wilcoxon test). Compliance and psychiatric clinics. To be included in the study reports of adverse effects were similar between they had to: be between 18 and 65 years of age; groups. fulfil DSM III criteria for anxiety disorder; have both somatic and psychic symptoms of anxiety; We thank ICI for supporting this study. have a minimum score of 16 on the Hamilton

Table 1 Hamilton anxiety scores for each treatment group (mean ± s.d.) ICI 118,551 Diazepam Placebo Week 0 23.7 ± 5.5 23.3 ± 3.8 23.1 ± 3.4 (17) (17) (17) Week 1 22.1 ± 5.8 22.0 ± 2.8 22.2 ± 3.8 (17) (17) (17) Week 3 19.4 ± 10.0 16.0 ± 7.5 18.3 ± 6.0 (16) (16) (16) Week 5 19.8 ± 9.1 15.5 ± 4.2 14.5 ± 2.8 (12) (13) (10) Figures in parentheses indicate number of patients remaining in trial.

Arnold, J. M. 0. et al. (1985). Br. J. clin. Pharmac., Jefferson, D. et al. (1987). Br. J. clin. Pharmac., 24, 19, 619. 729. Bonn, J. A. & Turner, P. (1971). Lancet, i, 135. Granville-Grossman, K. L. & Turner, P. (1966). Lancet, i, 788. 652P Proceedings of the BPS, 19-21 December 1988

Relative effects of digoxin and diltiazem addition, a battery of 'standard' psychomotor upon memory and psychomotor tests was performed including reaction time, performance in patients with AF letter cancellation and digit symbol substitu- tion. Nine subjects completed the study. There D. CURRIE*, R. V. LEWIS, J. McLAY, were weak positive relationships for scores B. TREGASKIS & D. G. McDEVIlT derived from each of the four memory tests Department of Clinical Pharmacology, Ninewells (meaned over the three trtatment periods) Hospital and Medical School, Dundee, DD1 9SY (mean r, = 0.51; range Or.234.96) There were significant relationships between each patient's Atrial fibrillation (AF) is a common cardiac mean memory score (MMS) (the arithmetic arrhythmia which is particularly prevalent mean of scores from each of the four memory amongst the elderly. Long term drug therapy is tests) between the three treatment periods often required to control the heart rate and (mean rs = 0.64; range 0.53-0.79) demon- digoxin is widely used for this purpose. How- strating intra-individual reproducibility of ever, there is concern that treatment with scoring between the treatment periods. Using cardiac glycosides may be associated with adverse data obtained at the end of each treatment central effects, particularly in the elderly, and period (day 7), the mean memory score was one study has demonstrated a dose-related compared between the three treatment periods impairment of memory among patients taking using the Friedman two-way analysis of variance. digoxin (Tucker & Ng, 1983). Rate-limiting There was a significant overall difference be- calcium antagonists such as verapamil and dil- tween the drugs (P < 0.003), mean scores for tiazem may be used as an alternative to digoxin diltiazem being significantly lower than those in the treatment of AF (Lewis et al., 1988) for both doses of digoxin (Table 1). In eight of although these, too, may have central effects in the nine patients, the mean memory score was man. The aim of our study was to examine the lowest during treatment with diltiazem. Mean relative effects of digoxin (at two dose levels) memory scores were similar during treatment and diltiazem upon memory and psychomotor with both dose levels of digoxin, although plasma performance in a population of patients with digoxin concentrations differed significantly at chronic AF. day 7 (0.80 vs 2.67 nmol 1-1, P < 0.001). When Ten patients (mean age 65.4, range 51-74 the four individual memory tests were examined years; five females) with chronic AF entered individually, all indicated similar trends (Table the study. All were taking digoxin on a long 1) but the differences were not statistically term basis (median dose 0.25 mg day-1). After significant. Examination of data obtained after training to plateau level, patients entered a 5 days of treatment did not show significant randomised balanced double-blind crossover differences between the three treatments. trial comprising three treatment periods, each There were no significant differences between of 7 days duration. The drugs taken during each the drugs for psychomotor tests or for subjective of the treatment ?eriods were as follows: difoxin assessments. 0.0625 mg day- ; digoxin 0.25 mg day- and There was no evidence of a dose-related im- diltiazem 120 mg twice daily. A placebo could pairment of memory during treatment with not be included for ethical reasons. Memory digoxin. There is a possibility that treatment was studied using four techniques namely name- with diltiazem may be associated with a greater face recognition tasks, immediate recall (IR), change in memory scoring than is treatment selective reminding (SR) and restrictive re- with digoxin. minding (RR) (Tucker & Ng, 1983) tests. In

Table 1 Mean 24 h HR Faces/Names IR SR RR MMS (beats min-') Digoxin 0.0625 mg 5.10 5.90 4.3 8.96 6.1 71.4 Digoxin 0.25 mg 5.67 6.00 5.0 8.56 6.3 67.6 Diltiazem 4.33 5.78 3.0 8.07 5.3 61.0

Lewis, R. V. et al. (1988). Eur. Heart J., 9, 279. Tucker, A. R. & Ng, K. I. (1983). Psychopharma- cology, 81, 86. Proceedings of the BPS, 19-21 December 1988 653P

Cognitive assessment and drug information 21 + 3, NS, 18 + 4 vs 21 + 4, P < 0.02 and in the elderly 18 + 4 vs 19 + 4, NS respectively. In the same groups the percentage of patients knowing the E. BURNS*, C. A. AUSTIN' & N. D. S. BAX indications for none or all of their drugs was 4 University Department of Pharmacology and Thera- vs 70, 11 vs 44 and 10 vs 42 respectively. CAPE peutics, Royal Hallamshire Hospital and 'Depart- scores (mean + s.d.) in these groups were 19 + ment of Geriatric Medicine, Nether Edge Hospital, 3 vs 21 + 3, NS, 17 + 5 vs 21 + 2, P < 0.01 Sheffield and 18 + 5 vs 20 + 4, NS respectively. For the group as a whole 24% of patients could name Poor compliance with drug therapy is a parti- none of their drugs; 35% knew all of the names cular problem in the elderly (Medication for the (CAPE 19 + 4 vs 21 + 4, P < 0.001). Overall Elderly, Royal College of Physicians, 1984). 9% of patients did not know the reasons for Impairment of cognitive function may result taking any of their drug therapy; 51% knew the in patients from this age group having a poor reasons for all of them (CAPE 17 + 4 vs 21 + understanding of their drug therapy and of its 3, P < 0.01). potential risks. We have examined the relation- In all 36 ADRs were reported by patients and ship between the cognitive function of elderly 13 by the doctor, with patient/doctor agreement patients and their knowledge of their drug in only seven cases. None of the 23 patients therapy and of its potential risks. taking non-steroidal anti-inflammatory drugs Cognitive function was assessed in 207 con- nor of the 11 patients taking oral hypogylcaemic secutive review geriatric outpatients using the agents knew of any treatment risks. None of the Information/Orientation and Mental Ability 15 patients taking warfarin knew the nature of sections of the Clifton Assessment Procedure any potential ADR but two knew not to take for the Elderly (CAPE): max score 23 (Pattie aspirin concurrently. Overall, 53% of patients & Gilliard 1979). Patients also completed felt they knew enough about the reasons for questionnaires concerning their drug therapy. their treatment and 33% felt they knew enough The patients' reports were compared with those about possible ADRs. Thirty-eight percent of their clinic doctor who prescribed their medi- wanted to know more about their treatment cation. and 47% about possible ADRs (CAPE scores Overall there was patient/doctor agreement not significantly different between either groups). on current drug therapy in 38% of patients. In Thus the patients' level of information about the three age groups (65-74 years (28% of the their therapy was low. CAPE assessment sug- clinic), 75-84 years (55%) and 85 years or more gests that overall the contribution of cognitive (17%)) patient/doctor agreement occurred in dysfunction to lack of patient information about 50, 36 and 21% of patients respectively. CAPE their drugs may be considerable. Many patients scores did not discriminate between the agree- would like more information about their drug ment/non-agreement groups. In the three age therapy; in view of the medical risks and eco- groups the percentage of patients who knew the nomic consequences of poor compliance better names of none or all of their drugs was 9 vs 55, methods of communicating with elderly patients 30 vs 28 and 27 vs 30 respectively. CAPE scores are required. (mean + s.d.) in those groups were 20 + 2 vs

Medication for the Elderly, Royal College of Phy- Pattie, A. H. & Gilleard, C. J. (1979). Manual of the sicians, 1984. Clifton Assessment Procedures for the Elderly (CAPE). Hodder and Stoughton.

Influence of exercise on plasma nitroglycerin It has been reported that exercise increases concentrations after transdermal application nitroglycerin (NTG) plasma concentrations following its transdermal application (Barkve R. A. LEFEBVRE*, M. G. BOGAERT, et al., 1986; Weber et al., 1987). In neither of 0. TEIRLYNCK' & A. SIOUFI2 these studies was there an appropriate control Heymans Institute of Pharmacology, University of session. We therefore performed a randomized Gent, Belgium, 'Ciba-Geigy, Brussels, Belgium and crossover study in strictly controlled conditions, 2Laboratoires Ciba-Geigy, Biopharmaceutical Re- on the influence of exercise (at 50% of the pre- search Centre, Rueil-Malmaison, France determined maximal work load on a bicycle 654P Proceedings of the BPS, 19-21 December 1988 ergometer). The study was approved by the ± s.d.) was 65 ± 6 and 64 ± 10 in the supine University Hospital Medical Ethics Committee. session, 64 ± 6 and 77 ± 11 in the sitting session Nine healthy volunteers (seven males, two and 63 ± 8 and 161 ± 12 in the exercising females; 21-26 years) participated in three session. Plasma NTG concentrations remained sessions, with 1 week intervals, in a room kept stable during the whole supine session while at constant temperature (23 ± 1° C). A trans- they increased moderately during sitting (Table dermal NTG plaster (Nitroderm TTS 10, Ciba- 1). After 15 and 20 min of exercise, there was Geigy) was applied to the chest 5 to 10 cm a pronounced increase of the plasma NTG con- below the middle of the right clavicle at time 0 centrations; the highest value was reached 5 (about 08.00 h), just before a standard breakfast. min after ending the exercise and the concen- Positions during the sessions were for time 0 to trations remained increased until the end of the 2 h: sitting; for 2 h to 3 h: supine; for 3 h to session. The difference in plasma NTG between 3 h 20 min: either supine or sitting or exercising; the supine, sitting and exercising session was for 3 h 20 min to 4 h 20 min: supine. Plasma significant (P < 0.05, ANOVA). samples were taken at different time intervals Changes in cutaneous and hepatic blood flow after the plaster application for determination might contribute to the pronounced and lasting of the plasma NTG concentration by capillary increase in plasma NTG due to exercise. gas chromatography with electron capture de- tection. This work was supported by Ciba-Geigy, Belgium. Just before and at the end of the randomized R.A.L. is a Research Associate of the National Fund 20 min period, heart rate (beats min-1, mean for Scientific Research (Belgium).

Table 1 Mean (± s.d.) results for plasma NTG concentrations (ng ml-') in the three sessions (sitting and exercising from 3 h to 3 h 20 min) Time Supine Sitting Exercising 2 h 45 min 0.28 (± 0.22) 0.30 (± 0.33) 0.19 (± 0.13) 3 h 0.39 (± 0.34) 0.31 (± 0.38) 0.22 (± 0.11) 3 h 05 min 0.38 (± 0.29) 0.25 (± 0.25) 0.09 (± 0.04) 3 h 15 min 0.40 (± 0.33) 0.52 (± 0.49) 0.83 (± 0.36) 3 h 20 min 0.43 (± 0.39) 0.55 (± 0.50) 0.85 (± 0.42) 3 h 25 min 0.42 (± 0.36) 0.45 (± 0.35) 1.26 (± 0.40) 4 h 05 min 0.38 (± 0.26) 0.31 (± 0.21) 0.84 (± 0.37) 4 h 20 min 0.37 (± 0.21) 0.27 (± 0.20) 0.64 (± 0.32)

Barkve, T. F. et al. (1986). Am. Heart J., 112, 537. Weber, S. et al. (1987). Br. J. clin. Pharmac., 23, 103.

The effects of lithium on Na/K pump tions by studying the Vmax and Km of ouabain- numbers and activity in human isolated sensitive potassium influx (measured using lymphocytes in vitro rubidium influx) and internal sodium concen- trations in lymphocytes after incubation in R. JENKINS* & J. K. ARONSON lithium (1-8 mM) in dialysed fetal calf serum for MRC Unit and University Department of Clinical 72 h. Pharmacology, Radcliffe Infirmary, Oxford OX2 6HE Lymphocytes were prepared from the venous blood of 22 healthy subjects (17 men, 5 women, Incubation of human lymphocytes for 72 h in aged 23-45 years), washed in culture medium lithium (1 mM) causes an increase in lympho- (RPMI 1640, Gibco), and incubated at 370 C in cyte Na/K pump numbers, as measured by air/CO2 (95%/5%) for 72 h in dialysed fetal calf specific ouabain binding (Rapeport et al., 1986). serum with or without lithium (final concen- Fetal calf serum also has this effect, but it is trations 1-8 mM). The cells were then washed removed by prior dialysis of the serum (Oh et in a K+-free Ringer and the following were al., 1987). We have extended these observa- measured: the Bmax of specific [3H]-ouabain Proceedings of the BPS, 19-21 December 1988 655P binding (Boon et al., 1984); the Vmax and Km of out changing the Km of influx or the turnover ouabain-sensitive rubidium influx (Oh et al., number. This suggests that the effect of lithium 1987); sodium concentrations (by emission flame is to increase Na/K pump numbers without photometry); and cell water (Lichtshtein et al., changing the activity of individual pumps. The 1979). fall in internal sodium concentration can be The effects of lithium (1-8 mM) were concen- attributed to the increase in pump numbers, tration-related, and the results of the experi- and this suggests that the effect of lithium is not ments with 8 mm lithium are shown in Table 1. mediated via a primary increase in sodium con- Thus, exposing lymphocytes to lithium for centration, a suggested mechanism for other 72 h caused an increase in the Bmax of ouabain stimuli which increase Na/K pump numbers binding and the Vmax of rubidium influx, with- (Rapeport et al., 1986).

Table 1 Specific ouabain binding, ouabain-sensitive rubidium uptake, and internal sodium concentrations in lymphocytes after incubation in lithium (8 mM) for 72 h. The results are given as mean (s.d.) No lithium Lithium 8 mM t-test Bmax of ouabain binding 42 008 53 534 P < 0.05 (sites/cell) (9984) (14 141) Vmax of rubidium influx 0.313 0.401 P < 0.05 (nmol 10-6 cells min-') (0.055) (0.071) Km of rubidium influx 0.551 0.556 NS (mmol l-1) (0.122) (0.066) Turnover number at Vmax 4487 4511 NS (ions site-' min-') (363) (393) Intracellular [Na] 65.5 45.4 P < 0.02 (mmol 1-l cell water) (16.9) (15.9)

Boon, N. A. et al. (1984). Br. J. clin. Pharmac., 18, Oh, V. M. S. et al. (1987). Clin. Sci., 72, 71-79. 153. Rapeport, W. G. et al. (1986). Br. J. clin. Pharmac., Lichtshtein, D. et al. (1979). Proc. Natl. Acad. Sci., 22, 275. 76, 650.

Captopril causes a fall in ANF and an anti- effects on renal sodium handling in different natriuresis in chronic heart failure parts of the nephron in patients with CHF. To do this we used the Li clearance technique. J. McLAY*, J. McMURRAY & A. D. STRUTHERS Fifteen patients aged 51-68 years (mean ± s.e. Department of Pharmacology and Clinical Pharma- mean 71 ± 2) with stable diuretic treated CHF cology, Ninewells Hospital and Medical School, were studied on 2 days. At 22.00 h prior to each Dundee DD1 9SY day patients ingested 300-60 mg of Li C03. At 09.00 h on day 1 a placebo (P) tablet was given. ACE inhibitors have recently become a stan- BP and HR were recorded every 15 min and dard part of therapy for chronic heart failure urine and blood collected after 2.5 h of supine (CHF). Renal blood flow is reduced in CHF rest. Captopril (CPT) was then given at 14.00 and intrarenal angiotensin II is thought to play and 22.00 h. At 09.00 h on day 2 a third dose an important role in maintaining glomerular of CPT was given and the same measurements filtration. Studies of ACE inhibitors in CHF made again for 2.5 h as on day 1 (i.e. after a have focused mainly on their haemodynamic cumulative dose of 25-75 mg of CPT). Mini- and symptomatic effects and there is relatively mum BP post-P was 119 ± 6/72 ± 3 mmHg and little information on the r-renal effects. post-CPT 95 ± 6/59 ± 3 mmHg (P < 0.01). We have now assessed their effects on seg- Creatinine clearance was (a) P 57 ± 4 (b) CPT mental nephron function, in particular their 57 ± 7 ml min-1 (P = NS). Fractional Na+ 656P Proceedings of the BPS, 19-21 December 1988 excretion (FENa+) was (a) P 0.86 ± 0.18% (b) Despite inhibition of the renin-angiotensin- CPT 0.34 ± 0.06% (P < 0.01). FELi (proximal aldosterone system, the acute response to CPT nephron outflow) was (a) P 23.6 ± 2.2% (b) was paradoxical in that an increase was seen in CPT 15.7 ± 2.6% (P < 0.001). CNa/CLi (distal proximal and distal nephron sodium reabsorp- nephron outflow) was (a) P 3.98 ± 0.81% (b) tion. This antinatriuretic effect of CPT could CPT 2.59 ± 0.41% (P < 0.01). PRA was (a) P reflect the fall in BP or the decrease in circu- 4.2 ± 4.7 (b) CPT 68.3 ± 153.5 ng ml-' h-1 (P lating ANF. The fall in plasma ANF after CPT < 0.001), aldosterone (a) P 264 ± 71 (b) CPT is presumably due to decreased cardiac filling 114 ± 24 pg ml-' (P = NS) and ANF (a) P 80 pressure and an improved haemodynamic ± 14 (b) CPT 61 ± 11 pmol 1-1 (P < 0.02). pattern.

Characteristic inter-species differences in Whilst the rank order of potency was different ACE inhibition for the two species, within species the rank order of potency for the two series of compounds was J. R. HARRIGAN, D. M. HUGHES & essentially the same (Table 1). P. A. MEREDITH Using pooled plasma from rabbit and man, University Department of Materia Medica, Stobhill the effects of enalapril and perindopril on the General Hospital, Glasgow G21 3UW potencies of their respective diacid metabolites were studied. The values for C(50) for the two Much of the early work to elucidate the struc- metabolites in the absence of parent drug were ture activity relationships and hence the dose- not significantly different from the values response relationship for ACE inhibitors has obtained for individual subjects. Parent drug been undertaken in animal species. For this concentrations were selected to give approxi- reason it was decided to compare the in vitro mately 5, 10 and 25% inhibition of ACE activity potencies of the active species of several ACE and the C(50) values of the metabolites re- inhibitors within individual rabbits and men, assessed. and in the case of enalapril and perindopril, to No effect of the parent drug on the C(50) of examine the effect of parent compound on the the metabolite was seen in the rabbit for either in vitro potency of the metabolite. compound studied. In man the presence of Two groups of studies have been carried out. enalapril caused small increases (21% maxi- In the first group the in vitro potencies of capto- mum) in the C(50) of enalaprilat but the in- pril, enalaprilat, perindoprilat and trando- crease was not related to the degree of inhibition laprilat were compared within eight individual caused by the enalapril. In contrast the presence rabbits and men. In the second group the in of perindopril (5, 10 and 50 ng ml-'), caused vitro potencies of enalaprilat, perindoprilat, up to a 109% increase in the C(50) of the meta- benazaprilat and S-10211 were compared within bolite and the increase was linearly related to six individual rabbits and men. Dose-response the degree of inhibition caused by the parent curves were spiked for each compound and drug. ACE activity was measured using an h.p.l.c. In conclusion, the findings of this study sug- method and the artificial substrate Hip-His-Leu. gest that there are significant inter-species dif- The generated dose-response curves were fitted ferences in the potency of ACE inhibitors. by Hill and Langmuir models and goodness of Additionally there is evidence with two ACE fit was tested using the F-ratio test. The in vitro inhibitors that, by a mechanism such as steric potency comparison was made using the C(50) hindrance, the parent drug may perturb the value, the fitted parameter value which describes concentration/ACE inhibition relationship of the concentration of the drug which produces the active diacid metabolites. 50% ACE inhibition. Proceedings of the BPS, 19-21 December 1988 657P Table 1 Mean C(50) (s.d.) (ng ml-') Captopril Enalaprilat Perindoprilat Trandolaprilat Man 107 (24.2) 7.21 (2.41) 2.59 (1.48) 1.10 (0.34) Rabbit 1029 (433) 1.64 (0.41) 1.02 (0.33) 1.84 (0.54) Benazaprilat Enalaprilat Perindoprilat S-10211 Man 5.14 (1.08) 6.29 (2.02) 1.36 (0.22) 2.43 (1.33) Rabbit 1.14 (0.12) 1.86 (0.33) 0.87 (0.13) 0.94 (0.16)

The effects of sulindac on the cough Cough reflex sensitivity was measured by in- associated with angiotensin converting halation of single breaths of capsaicin at doses enzyme inhibitor therapy 0.2-50 nmol, or saline, in random order and the number of coughs recorded by a microphone. N. CHOUDRY, J. R. McEWAN* & The dose of capsaicin producing two or more R. W. FULLER coughs (D2) was taken as threshold sensitivity Department of Clinical Pharmacology and Medicine, while that causing five or more coughs (Ds) Royal Postgraduate Medical School, Hammersmith was taken as that producing near maximum re- Hospital, London W12 ONN sponse. Each are expressed as geometric mean (95% confidence intervals). The symptom of Cough is now recognised as a side effect of cough was assessed on a daily scale of 0 to 20 angiotensin converting enzyme inhibitor (ACE-I) with 20 being most troublesome and 0 no cough therapy. We have previously reported that this at all and the weekly total score analysed. Results cough is associated with a reversible increase were analysed by two-way analysis of variance in the sensitivity of the cough reflex (Fuller and a P < 0.05 accepted as significant. & Choudry, 1987). It has been suggested that Mean BP before placebo therapy was 169/97 sulindac, a non steroidal anti-inflammatory mmHg, 146/90 mmHg before sulindac therapy, agent, will alleviate the cough of ACE-I therapy 153/94 mmHg after placebo and 159/94 after (Nicholls & Gilchrist, 1987). We have now sulindac. None of these differences was signifi- compared the effect of placebo and sulindac cant. 200 mg/day on blood pressure (BP), cough There was no significant difference in the D2 symptoms and the capsaicin stimulated cough or D5 before or after placebo or before sulindac reflex in a double-blind crossover study. Six but after sulindac there was a significant increase patients were studied, three female aged 46-71, in both D2 (P < 0.05) and D5 (P < 0.01) (Table mean 59 years. All had been prescribed an 1). There was a significant fall in the median ACE-I, four captopril and two enalapril, as part cough symptom score for the week on sulindac of their treatment for benign essential hyper- (P < 0.05). tension. Each had complained of cough while These results confirm that sulindac both taking the ACE-I and had been demonstrated alleviates the symptom of cough and reduces to have a hypersensitive cough response to the associated hypersensitivity of the cough capsaicin. Each patient was studied for two reflex in those patients who have a cough while periods of 1 week at least 1 week apart. The on ACE-I and support a role for prostaglandins antihypertensive medication was continued un- in its genesis. changed throughout the study. Supine blood pressure, symptoms of cough and cough reflex We acknowledge support from the Medical Research sensitivity were recorded before and at the end Council and Merck Sharp & Dohme. JRMcE is an of each treatment period. MRC Junior Training Fellow. 658P Proceedings of the BPS, 19-21 December 1988 Table 1 Median weekly D2 (nmol) D5 (nmol) cough score (range) Before placebo 0.28 (0.16-0.49) 0.89 (0.24-3.3) After placebo 0.36 (0.22-0.59) 0.64 (0.28-1.5) 38 (0-58) Before sulindac 0.25 (0.14-0.45) 1.26 (0.5-3.2) After sulindac 0.64 (0.28-1.46) 4.02 (1.0-16) 20 (2-41)

Fuller, R. W. & Choudry, N. B. (1987). Br. med. J., Nicholls, M. G. & Chilchrist, N. L. (1987). Br. med. 295, 1025. J., 295, 872.

Additive antihypertensive effects of 25 mg HCTZ in a 1 month double-blind parallel perindopril and hydrochlorothiazide: group study (10 patients in each group). Blood A double-blind parallel group study pressure and heart rate were measured in supine and erect positions and blood samples were C. I. BACKHOUSE, CHLOE L. BROWN*, taken for the measurement of plasma renin J. C. GRIPPAT' & J. PH. SANTONI2 activity (PRA) plasma.aldosterone and serum The Medical Centre, East Horsley, Surrey, *Servier ACE activity at the end of the placebo period Research and Development, Fulmer Hall, Fulmer, and 24 h after the last dose of the 1 month SL3 6HH, 'Pragmapharm International, 75116 Paris treatment period. Routine haematology and and 2IR.I. Servier, 92202 Neuilly-sur-Seine, France serum biochemistry were also performed and side-effects recorded at these visits. Perindopril is an orally active, long-lasting The treatment groups were homogenous for angiotensin converting enzyme (ACE) inhibitor all blood pressure, heart rate and renin-angio- (Lees & Reid, 1987). Clinical studies with per- tensin system parameters and all patients com- indopril have shown that when blood pressure pleted the study. The antihypertensive effects normalisation is not obtained using mono- of 4 mg perindopril and 25 mg HCTZ were therapy, the antihypertensive effect can be confirmed and shown to be additive. The effect augmented on the addition of a thiazide diuretic. of the combination on PRA was greater than In view of the likelihood of their concurrent that of perindopril or HCTZ alone (Table 1). administration, the interaction of perindopril No significant effects were seen on heart rate and hydrochlorothiazide (HCTZ) was studied or weight in any group and there were no signi- in patients with mild to moderate essential hyper- ficant intergroup differences in biochemical or tension. haematological parameters. The few minor side- Forty patients aged between 18 and 70 years effects reported were no more frequent in the and with supine diastolic blood pressure between group receiving the combined treatment than in 95 and 115 mmHg at the end of a 2 week those receiving single drug therapy. The com- placebo period were randomly allocated to re- bination of 4 mg perindopril and 25 mg HCTZ ceive daily treatment with placebo, 4 mg per- was a well tolerated and effective antihyper- indopril, 25 mg HCTZ or 4 mg perindopril + tensive treatment. Proceedings of the BPS, 19-21 December 1988 659P

Table 1 Mean change after treatment Perindopril 4 mg Parameter Placebo Perindopril 4 mg HCTZ 25 mg + HCTZ 25 mg Supine SBP (mmHg) -3.8 -11.0* -11.3* -24.5*a Supine DPB (mmHg) -3.8 -7.4* -7.6* -12.6* Erect SBP (mmHg) -3.7 -8.3 -11.6* -28.1*b Erect DBP (mmHg) -1.7 -6.4 -6.4* -12.3*a ACE activity (%) +3 -59* -4 -49* PRA (%) +2 +52* +48 +217*b Aldosterone (%) 12 -51 +8 +46b *significant change after 1 month's treatment Intragroup-2 way ANOVA. asignificantly different from placebo Intergroup-1 way ANOVA of changes bsignificantly different from single treatments 5% level of significance

Lees, K. R. & Reid, J. L. (1987). Br. J. clin. Pharmac., 23, 159.

Effect of enalapril and atenolol alone or in (A+E) 100 mg and 10 mg respectively. For 3 combination on blood pressure in healthy days before each study day, volunteers were volunteers provided with a restricted sodium diet (approx- imately 20 mmol). Compliance was checked by A. J. NICHOLLS*, J. E. PARKER & J. POSNER measurement of 24 h Na excretion. Measure- Wellcome Research Laboratories, Beckenham, Kent ments of blood pressure (BP) (automatic BR3 3BS sphygmomanometer) were made 30 min before and 2, 4, 6 and 8 h after drug administration. Previous reports of the interaction between Data were subjected to analysis of covariance ACE inhibitors and 3-adrenoceptor blockers (-30 min value as covariate). There were no when combined for the treatment of hyper- occasion effects. Mean values of BP are given tension have described both potentiation (Mac- in Table 1. Gregor et al., 1982) and suppression (Staessen E and A alone significantly reduced supine et al., 1982) of the therapeutic effect of the and erect BP. At 2, 4, 6 and 8 h post dose, single agents. A double-blind, placebo con- A+E produced a significantly greater hypo- trolled study was conducted in sodium restricted tensive effect than either agent alone (P < 0.05, normotensive volunteers in order to examine at each time point). Erect BP showed a similar this interaction further. response except that the comparison of A with Eight healthy male volunteers (BP < 140/90 A+E was not significant at 2 and 4 h. In salt mmHg; age range 26-31 years) received each of restricted volunteers a single dose of the agents four treatments in random order at 7 day inter- enalapril and atenolol in combination produced vals. These treatments, presented in identical a greater effect on blood pressure than either capsules, were placebo (P), atenolol 100 mg agent alone. (A), enalapril 10 mg (E) and the combination 660P Proceedings of the BPS, 19-21 December 1988 Table 1 Blood pressure (systolic/diastolic (mmHg) -30 min 2h 4h 6h 8h Supine P 121.7/60.0 118.2/60.0 113.9/59.7 114.2/61.3 118.3/63.3 A 120.6/62.2 110.4/59.3 105.2/54.4 105.0/53.6 110.0/52.5 E 120.0/64.9 116.4/61.4 113.0/58.2 108.5/54.8 112.3/59.3 A and E 121.0/64.5 106.2/54.0 96.1/49.6 98.6/43.9 101.7/47.9 Erect P 121.0/72.3 121.3/69.9 119.0/72.3 119.5/69.8 121.9/71.4 A 117.7/69.5 104.3/60.5 105.2/60.2 106.6/60.4 109.4/63.8 E 122.7/4.5 117.6/70.6 109.8/64.4 112.5/66.8 111.0/61.9 A and E 123.4/73.7 103.8/61.4 100.8/57.4 95.4/51.8 100.2/52.6

MacGregor, G. A. et al. (1982). Br. med. J., 284, Staessen, J. et al. (1982). Am. Heart J., 106, 321. 1535.

3-adrenoceptor changes in leucocyte in intact cells as recently described (Brodde et subpopulations after isoprenaline-infusion al., 1988). in healthy volunteers IPN-infusion (3.5; 7; 17.5; 35 and 70 ng kg-' min-1 for S min each) led to a small but signifi- L. J. H. VAN TITS*, H. GROSSE-WILDE1, cant increase of peripheral blood lymphocyte M. HAPPEL1, A. M. KHALIFA & O.-E. BRODDE counts, amounting to 26.3 ± 6.9%. This increase Biochemical Research Laboratories Med. Klinik and was predominantly due to a large increase in T.- Poliklinik, Division of Renal and Hypertensive cell number (107 ± 18%), while Th-cell number Diseases, and 'Institute for Immunogenetics, Univer- was decreased, but to a smaller extent (41.1 ± sity of Essen, D-4300 Essen, FRG 3.3%). Thus, IPN-infusion led to a significant change in the Th/Ts-cell ratio from 1.7 ± 0.1 to Apart from increasing P2-adrenoceptor (AR) 0.5 ± 0.1. In addition, a reduced lymphocyte density (Brodde et al., 1988), ,3-AR stimula- proliferative in vitro response (measured by [3H]- tion also influences distribution of lymphocyte thymidine uptake) upon mitogen stimulation subsets in peripheral blood of humans (Crary et was observed. Monocyte and B-cell counts did al., 1983). Since lymphocyte subsets seem to not change significantly. have markedly different 132-AR densities (Khan P2-AR density on unfractionated MNC in- et al., 1986; Landmann et al., 1984) it is tempt- creased from 1146 ± 59 before to 2245 ± 164 ing to speculate that the increase in P2-AR ICYP binding sites/cell after IPN-infusion. density is due to an altered composition of Examination of lymphocyte subsets revealed lymphocyte subsets. To investigate this hypo- significantly higher densities of basal 132-AR on thesis we studied 132-AR densities on mono- B-cells compared with T-cells (1779 ± 121 and nuclear cells (MNC) and different lymphocyte 1047 ± 54, respectively) and on T.-cells com- subsets as well as the distribution of these cells pared with Th-cells (1511 ± 154 and 1086 + in blood of 10 healthy volunteers (aged 20-31 140, respectively). 132-AR densities on B-cells years) before and after isoprenaline (IPN)- as well as T-cells and on Th-cells as well as T,- infusion simultaneously. In addition, we cells were increased two-fold in comparison to measured P2-AR density on monocytes and their basal values following the IPN-infusion. platelets. The affinity of ICYP to the P2-AR did not Purified lymphocyte subsets were obtained change significantly. On the other hand, mono- by the 'panning' technique using monoclonal cyte and platelet 132-AR densities were not antibodies to fractionate MNC into T-, B-, T- affected by the IPN-infusion. suppressor (T.) and T-helper-(Th) cells. The We conclude that 1-AR stimulation by IPN- phenotypes of MNC and isolated lymphocyte infusion causes simultaneously a significantly subsets were analyzed by indirect immuno- altered distribution of lymphocyte subsets and fluorescence. P2-AR density was determined an increase in 12-AR density in B-, Th- and Ts- by (-)-['25I]-iodocyanopindolol (ICYP) binding cells. Proceedings of the BPS, 19-21 December 1988 661P

This work was supported by the Sandoz-Stiftung fur Therapeutische Forschung.

Brodde, O.-E. et al. (1988). Am. J. Physiol., 254, Khan, M. M. et al. (1986). Biochem. Pharmac., 35, H199. 1137. Crary, B. et al. (1983). J. Immunol., 131, 1178. Landmann, R. M. A. et al. (1984). J. receptor Res., 4, 37.

Myocardial 13- and 132-adrenoceptor III to class IV. However,. in none of the tissues alterations in patients with mitral valve was the relative amount of ,1- and 132-AR disease changed; in addition, in right atrial and left ventricular membranes the P1: 32-AR ratio O.-E. BRODDE*, N. DOETSCH', M. C. MICHEL, was not different from data obtained in tissues C. WIRTH' & H.-R. ZERKOWSKI' from non-failing hearts. This indicates, that in Biochemical Research Laboratories, Med. Klinik and mitral valve disease the decrease in 1-AR Poliklinik, Division of Renal and Hypertensive density is due to a concomitant decrease in 1l- Diseases and 'Division of Thoracic and Cardio- and 132-AR. The decreased 1-AR density was vascular Surgery, University of Essen, D-4300 Essen, accompanied by a loss in P-AR functional FRG responsiveness: in isolated electrically driven right atria the pD2-values for the positive ino- In patients suffering from end-stage congestive tropic effects of isoprenaline (IPN: 6.63 vs 7.73), cardiomyopathy a selective decrease of cardiac noradrenaline (1,l-AR mediated: 5.91 vs 6.80) P1l-adrenoceptor (AR) density-presumably and procaterol ()2-AR mediated: 7.43 vs 8.04) due to the markedly elevated noradrenaline were significantly reduced when compared with levels-has been described (Brodde et al., 1986; those obtained in right atria from patients with Bristow et al., 1986). To find out whether such coronary artery disease and very mild heart a selective loss in cardiac 13-AR function is failure (NYHA class I-II). Moreover, in isolated a general phenomenon for all kinds of heart electrically driven left papillary muscles the pD2- failure, we determined 13-AR density, subtype value for IPN-induced positive inotropic effects distribution and functional responsiveness in declined concomitantly with 13-AR density (see right and left atria as well as in left papillary above), when the degree of¶eart failure in- muscles from patients with mitral valve disease. creased (NYHA III: 6.36; NYIIA III-IV: 6.03; Myocardial tissues were obtained from 35 NYHA IV: 5.53). Interestingly, on isolated patients (NYHA functional class III-IV) under- electrically driven left papillary muscles and left going mitral valve replacement for either mitral atria 1 I.LM forskolin-added at the end of the stenosis or mitral regurgitation. None of the IPN-concentration-response curve into the patients had been treated with 1-AR antagonists organ-bath-produced marked additional in- or had received catecholamines for at least 3 creases in contractile force. weeks before operation. 1-AR density and It is concluded that (i) a decrease in cardiac subtype distribution in cardiac membranes was 3-AR function is a general phenomenon in determined by (-)-[1251]-iodocyanopindolol heart failure, (ii) this decrease is related to the binding as recently described (Michel et al., degree of heart failure and (iii) in contrast to 1988). Furthermore, contractile responses to congestive cardiomyopathy in mitral valve 13-AR agonists were determined on isolated disease the decrease in cardiac 1-AR function electrically driven right atria and left papillary is due to a concomitant decrease in 13- and muscles as detailed elsewhere (Zerkowski et al., P2-AR. 1986). In all three tissues cardiac 1-AR density This work was supported by the Sandoz-Stiftung fur gradually declined when the degree of heart Therapeutische Forschung (O.-E.B.) and the Deutsche failure increased from NYHA functional class Forschungsgemeinschaft (DFG Ze 218/1-3; H.-R.Z.).

Bristow, M. R. et al. (1986). Circ. Res., 59, 297. Michel, M. C. et al. (1988). Br. J. Pharmac., 94, 685. Brodde, O.-E. et al. (1986). J. cardiovasc. Pharmac., Zerkowski, H.-R. et al. (1986). Naunyn-Schmiedeberg's 8, 1235. Arch. Pharmac., 332, 142. 662P Proceedings of the BPS, 19-21 December 1988

ECG and systemic responses to inhaled compared by repeated measures analysis of salbutamol are due to pulmonary rather variance (MANOVA). Values are shown as than gut absorption means and 95% confidence intervals. There were highly significant hypokalaemic B. J. LIPWORTH*, D. G. McDEVITFT & responses to salbutamol (P < 0.001): 3.70 mmol A. D. STRUTHERS F-1 (3.46-3.95) to 3.20 mmol 1-1 (2.91-3.49) Department of Clinical Pharmacology, Ninewells MDI, 3.78 mmol 1-1 (3.61-3.95) to 3.18 mmol Hospital and Medical School, Dundee, DD1 9SY I1- (3.06-3.30) PSS. Salbutamol produced marked ECG effects including T wave flatten- We have previously shown that improvements ing (P < 0.001): 0.46 mV (0.24-0.68) to 0.22 in bronchodilatation with high dose inhaled mV (0.07-0.37) MDI, 0.50 mV (0.23-0.77) to salbutamol are associated with systemic adverse 0.24 mV (0.07-0.41) PSS, and Q-Tc interval effects, including hypokalaemia (Lipworth et prolongation (P < 0.001): 0.382s (0.372-0.392) al., 1988a, b). Radiotracer studies have shown to 0.409s (0.397-0.421) MDI, 0.378s (0.358- that the use of a pear-shaped spacer attachment 0.398) to 0.410s (0.388-0.432) PSS. U waves (PSS) results in improved airways delivery and occurred in five subjects with MDI and four marked reduction in oropharyngeal deposition with PSS. S-T segment depression was present of metered-dose inhaled (MDI) aerosol (New- in two subjects with MDI and in three with PSS. man et al., 1984). The purposes of the present These changes were not however associated study were twofold. Firstly, we have investi- with ventricular extrasystoles. There were gated in detail the electrocardiographic (ECG) chronotropic effects (P < 0.001): 63 beats min-' sequelae of high doses of inhaled salbutamol. (57-70) to 79 beats min-1 (69-89) MDI, 58 Secondly, we have assessed the pulmonary and beats min-' (53-63) to 75 beats min-' (69-81) gastrointestinal components of inhaled sal- PSS; along with a small rise in SBP (P < 0.001) butamol absorption by comparing systemic ,B- and fall in DBP (P < 0.001). Comparison of adrenoceptor responses with MDI alone, to DRCs for MDI alone and with PSS showed no those with PSS. significant differences, for any of the variables Seven normal subjects (age 31 ± 2 years) measured. were given cumulative doubling doses of inhaled In summary, these results show that marked salbutamol (from 100 ,ug to 2000 ,ug), either by ECG changes occur with high dose inhaled sal- MDI alone, or in conjunction with PSS. Plasma butamol in normal subjects. The use of a PSS potassium (K), ECG, heart rate (HR) and blood did not attenuate systemic ,B-adrenoceptor pressure (SBP and DBP) were measured at each responses, suggesting that these effects were dose increment, made every 20 min. Dose- due to pulmonary rather than gastrointestinal response curves (DRC) with MDI or PSS were absorption.

Lipworth, B. J. et al. (1988a). Br. J. clin. Pharmac., Lipworth, B. J. et al. (1988b). Br. J. clin. Pharmac., 25, 625P. 25, 667P. Newman, S. P. et al. (1984). Thorax, 30, 935.

A preliminary study of fenoldopam in the vasodilation in man. Haemodynamic studies treatment of chronic left ventricular failure suggest that it may be of benefit in the treat- due to ischaemic heart disease ment of heart failure (Leon et al., 1986). We have studied the effects of 6 weeks' oral treat- T. M. MacDONALD*, R. F. JEFFREY1, ment with fenoldopam on exercise tolerance in A. L. MUIR2 & M. R. LEE3 patients with left ventricular failure secondary Department of Medicine and Therapeutics, Polwarth to ischaemic heart disease. Building, Foresterhill, Aberdeen AB9 2ZD, 1Renal Twenty patients (five female, mean age 62 Unit Western Infirmary, Glasgow, 2Departments range 53-70 years) all of whom had NYHA of Medicine and 3Clinical Pharmacology, Royal grade II to III heart failure due to documented Infirmary, Edinburgh EH3 9YW ischaemic heart disease were recruited over 2.5 years. All had left ventricular ejection fractions Fenoldopam (SKF 82526) is a DA1 dopamine- (LVEF) of less than 30% on radionuclide ven- receptor agonist which causes renal and arterial triculography. All had been clinically stable on Proceedings of the BPS, 19-21 December 1988 663P fixed dose of frusemide for 1 month prior to Six patients taking fenoldopam completed entry. None was taking digoxin, vasodilators or the study five of whom were taking full dosage. ACE inhibitors. Two were withdrawn with worsening symptoms Patients underwent exercise capacity testing one of whom developed atrial fibrillation. One on a bicycle ergometer, the results being ex- died suddenly and one withdrew for personal pressed as Joules of energy expended. At base- reasons. One patient was withdrawn from the line no patient was able to exercise more than placebo group with worsening symptoms. Exer- 33,600 J (10 min) but all exercised at least 2,400 J cise capacity did not statistically significantly (2 min). Baseline exercise testing was per- increase at either 3 or 6 weeks on fenoldopam formed in duplicate on each of 2 days (mean of or placebo. The five patients who completed four tests) and patients entered the study when the study on 100 mg fenoldopam all increased the means of these 2 days were less than 10% their exercise tolerance (mean % increase in different. Patients received fenoldopam 50 mg energy expenditure, 24.5% range 0.5% to three times daily or matching placebo for the 55.9%) but this was not statistically different first week of treatment in a double-blind, ran- from placebo. There were no significant changes domised, parallel group fashion. Thereafter in LVEF in either group. they received fenoldopam 100 mg or placebo In this preliminary study patients treated with for a further 5 weeks. Patients experiencing side fenoldopam did not demonstrate a statistically effects at 100 mg were changed back to 50 mg. significant benefit over placebo. Exercise testing was repeated at 3 and 6 weeks and pre and post treatment LVEF was measured.

Leon, C. A. et al. (1986). J. Am. Coll. Cardiol., 7, 70A.

The 5-HT induced biphasic vasodilatation and 500 ng kg-i min-'. Forearm blood flow in the human forearm is dose-dependently (FBF) was measured by computerized R-wave antagonised by ICS 205-930 triggered venous occlusion plethysmography. Heart rate and blood pressure were recorded G. J. BLAUWi*, P. VAN BRUMMELEN2 & P. A. semi-continuously. VAN ZWIETEN3 The low dose of 5-HT induced a biphasic iDepartment of Nephrology, University Hospital dilatator response, consisting of an initial rapid Leiden, The Netherlands, 2Department of Clinical transient vasodilatation, followed by a persis- Research, F. Hoffmann-La Roche & Co. Ltd, Basel, tent increase in FBF (Table 1, P < 0.05 for Switzerland, 3Department of Pharmacotherapy, both). The high dose of 5-HT elicited a similar Academic Medical Centre, Amsterdam, The Nether- initial transient vasodilatation (P < 0.05), but lands the mean value of the second vascular response was not significantly different from baseline Recently, we have provided evidence that the (Table 1). The results of the combined infusions serotonin (5-HT) induced biphasic vasodila- of 5-HT and ICS are given in Table 1. tation in the human forearm is mediated by These results show that the biphasic dilatator stimulation of a 5-HT3 receptor subtype present response to a low dose of 5-HT is dose-depen- on sensory neurons (Blauw et al., 1988a). In the dently attenuated by ICS, and confirms our present study we further investigated the pos- previous finding that a 5-HT3 receptor could sible role of a 5-HT3 receptor in the vasodila- be involved in the dilatator response to 5-HT tator response to 5-HT in man, by using dif- (Blauw et al., 1988a). The fact that the high dose ferent doses of the 5-HT3 receptor antagonist of 5-HT induced a net vasoconstriction during ICS 205-930 (ICS). the infusion of ICS 500 ng kg-1 min- , provides In seven healthy male volunteers (age 21-27 evidence that the vascular response to 5-HT is years) 5-HT was infused into the brachial artery determined by at least two different receptor in cumulative doses of 1 and 50 ng kg-1 min-1 subtypes: a 5-HT3 and a 5-HT2 receptor me- together with saline. Each dose was given for diating vasodilatation and vasoconstriction, 6 min. Subsequently the same doses of 5-HT respectively (Blauw et al., 1988b). So far, dose- were administered together with ICS 10, 100 dependency of the initial transient response to 664P Proceedings of the BPS, 19-21 December 1988 5-HT has not been established (Blauw et attenuated by ICS, whereas the initial dilatator al., 1988b; Roddie et al., 1955). However, the response to the high dose of 5-HT was not in- present finding that the initial transient vaso- fluenced by ICS, suggests that this effect might dilatation induced by the low dose of 5-HT was be dose-dependent.

Table 1 Results (mean ± s.e. mean) Infiusion (ng kg-' min-') A FBF-lst phase (%) A FBF-2nd phase (%) 5-HT 1 + saline 207 ± 34 43 ± 7* 5-HT 1 + ICS 10 158 ± 18 39 ± 9 5-HT 1 + ICS 100 88 ± 33* 26 ± 10 5-HT 1 + ICS 500 18 ± 5 -5 + 9* 5-HT 50 + saline 176 ± 34 2 ± 8 5-HT 50 + ICS 10 230 ± 43 4 11 5-HT 50 + ICS 100 208 ± 45 -10 ± 9 5-HT 50 + ICS 500 193 ± 36 -19 7 *P < 0.05 compared with 5-HT + saline (multiple analysis of variance, MANOVA)

Blauw, G. J. et al. (1988a). Life Sci., 43, 1441. Roddie, I. C. et al. (1955). Br. J. Pharmac., 10, 445. Blauw, G. J. et al. (1988b). Hypertension, 11, 256.

An optimal function for fitting drug of drug molecules in the body (Wise, 1985) or concentration-time data? on the attraction of using a compact empirical function (Piotrovskii, 1987). P. R. JACKSON* & G. T. TUCKER We have fitted polyexponential, gamma and Department of Pharmacology and Therapeutics, Weibull functions to large drug concentration- University of Sheffield, Royal Hallamshire Hospital, time data sets for amiodarone and cisplatin. Sheffield Information criteria (Akaike, Schwarz and Leonard) were used to determine the best func- Drug concentration-time data have been fitted tion. The fit by the polyexponential expression using sums of exponentials based on the con- to both data sets was superior to that of the cept of the body as a series of discrete com- Weibull and gamma functions (Table 1). For partments with movement of drug between the amiodarone data comparisons were made compartments by first order kinetics. These between the areas under the drug-concentration compartmental models are unsatisfactory as time curve using the trapezoidal method and by their parameters are not uniquely identifiable integration of each of the functions. For all but and, with few exceptions, the amounts of drug one subject the AUCs derived from the poly- in the compartments do not correlate with ex- exponential fits gave the best approximation to perimentally determined drug content of body AUCs obtained by direct integration of the data tissues. Despite these failures of compartmental (Table 2). models the use of polyexponential functions Because of the failings of compartmental continues as they are flexible yet well behaved models a new theoretical basis is required to for the purposes of integration and extrapolation explain the polyexponential behaviour of drug Alternative expressions have been suggested. concentration-time data. based either on a stochastic view of the behaviour Proceedings of the BPS, 19-21 December 1988 665P

Table 1 Estimates of goodness of fit (Akaike information criterion) Amiodarone Cisplatin Method 1 2 3 4 5 6 1 Polyexponential -60.9 -6.7 -53.6 -42.0 -35.8 -81.3 -32.0 Gamma -26.4 13.8 -24.6 -26.5 -27.4 -49.2 -16.7 Weibull -45.2 26.0 -15.0 -19.3 -18.7 -42.0 -11.1

Table 2 Estimated AUCs for amiodarone (,ug 1-l h) Subject Method 1 2 3 4 5 6 Data 42.9 56.6 31.6 55.5 54.5 33.1 Polyexponential 41.3 64.3 31.2 54.0 53.5 32.5 Gamma 30.6 55.5 13.2 50.9 50.6 30.1 Weibull 37.0 55.8 16.1 50.4 52.7 32.2

Piotrovskii, V. K. (1987). Eur. J. clin. Pharmac., 32, Wise, M. E. (1985). J. Pharmacokin. Biopharm., 13, 515. 309.

Decreased al-acid glycoprotein concen- years). Protein binding of lignocaine was deter- tration and the plasma protein binding of mined also in twenty-five control patients lignocaine in cirrhosis (mean age 50 years, 20 male) without evidence of liver dysfunction. The concentration of AAG M. BARRY*, P. W. N. KEELING & J. FEELY was determined in twenty cirrhotics and fifteen Departments of Pharmacology and Therapeutics and control patients by radial immunodiffusion. Clinical Medicine, Trinity Medical School, St James's Plasma protein binding was determined at 370 C Hospital, Dublin 8 by equilibrium dialysis. 14C-radiolabelled ligno- caine was added to yield a concentration of 0.9 a1-acid glycoprotein (AAG) is the major ,ug ml-'. The results (mean ± s.e. mean) are determinant of plasma protein binding of basic shown in Table 1. drugs in man. It is subject to marked fluctua- There was a twofold increase in free lignocaine tions resulting in significant alterations in plasma accompanied by a significant reduction in AAG protein binding of basic drugs in health and in cirrhosis. A significant negative correlation disease states (Routledge, 1986). In cirrhosis (r = -0.78, P < 0.01) was found between free the AAG concentration has been reported as lignocaine and AAG (Figure 1). unchanged (Teirlynck et al., 1982) and decreased The toxicity of lignocaine appears to be related (Barre et al., 1987). more closely to free than to total lignocaine In this study we examined the effect of cir- concentration (Pieper et al., 1980). The doubling rhosis of the liver on AAG levels and the sub- in free lignocaine found in this study together sequent effect on the plasma protein binding of with a reduced clearance in cirrhosis may ex- the antiarrhythmic/local anaesthetic lignocaine. plain the clinical observation that these patients Thirty patients, 22 male, >with histologically are particularly susceptible to lignocaine toxi- diagnosed cirrhosis were studied (mean age 55 city.

Table 1 Control Cirrhosis P value Lignocaine binding (%) 69 ± 2 35 ± 2 P < 0.01 al-acid glycoprotein (mg dl-1) 77 ± 7 37 ± 3 P< 0.01 666P Proceedings of the BPS, 19-21 December 1988

80

; 70 - O O X 0) 0~~~ - 50

Ar

I v10 20 30 40 50 60 70 AAG (mg dl-') Figure 1 Relationship between AAG and free lignocaine in cirrhosis.

Barre, J. et al. (1987). Br. J. clin. Pharmac., 23, 753. Routledge, P. A. (1986). Br. J. clin. Pharmac., 22, Pieper, J. A. et al. (1980). Circulation, 62 (Suppl. 3), 499. III-181. Teirlynck, 0. et al. (1982). Eur. J. clin. Pharmac., 21, 427-431.

POSTER COMMUNICATIONS

Cryopreservation of human adult Leibowitz L15 (Rall & Fahy, 1985). Hepato- hepatocytes for toxicity studies cytes were frozen at 10 min- to -80° C. They were stored for up to 14 days, then thawed J. A. COUNDOURIS* 2, M. H. GRANT', rapidly at 370 C and washed twice with Leibowitz J. ENGESET3, J. C. PETRIE' & L15 medium before assessment of viability and G. M. HAWKSWORTH metabolic activity. 1 2Clinical Pharmacology Unit, 'Departments of Both the viability and the metabolic activity Medicine and Therapeutics, 2Pharmacology and were significantly better maintained with the 3Surgery, University of Aberdeen, Aberdeen VS. Cytochrome P450 and associated enzyme activities were well maintained over the 14 day The use of human adult hepatocytes for drug period as shown in Table 1. metabolism and toxicity studies overcomes the However, cellular reduced glutathione difficulty of extrapolation from animal data. (GSH) and the GSH conjugation of 1-chloro-2, The aim of this study was to extend the useful 4-dinitrobenzene declined from 65% and 63% lifetime of human hepatocyte preparations by of the fresh cell values after storage for 1 day optimising the conditions for maintenance of to 50% and 40% after storage for 14 days. The drug metabolising enzyme activities after cryo- decline in GSH-S-transferase activity was not preservation. Human adult hepatocytes were due to loss of GSH, since the assays were per- obtained by collagenase perfusion of approxi- formed in the presence of excess GSH. Gluta- mately 50 g liver sections from eight renal trans- thione reductase activity was also maintained plant donors (Strom et al., 1982). The viability at a low level (35% of the fresh cell values) of the freshly isolated hepatocytes ranged from throughout the 14 day, suggesting that hepato- 69-93%, with recoveries of between 500 and cyte cytosolic enzymes may be more susceptible 900 x 106 cells. Two cryoprotectant media were to damage by freezing than the microsomal compared: (1) a dimethylsulphoxide (DMSO) enzymes. based cryoprotectant which consisted of 20% For use in short-term toxicity studies, cryo- (v/v) DMSO and 25% (v/v) foetal calf serum in preserved hepatocytes must remain viable on Leibowitz L 15 medium and (2) a vitrification incubation at 370 C. When freshly isolated and solution (VS) composed of 20.5% (w/v) DMSO cryopreserved cells were incubated in Leibowitz 6% (w/v) polyethylene glycol 8000, 15.5% (w/v) L15 medium containing 1% (w/v) bovine serum acetamide and 10% (w/v) propylene glycol in albumin, the viability after 30 min was 70% of Proceedings of the BPS, 19-21 December 1988 667P the initial viability at time 0. This is in marked to 40% after 30 min. These results confirm the contrast to rat hepatocytes where the viability suitability of cryopreserved human hepatocytes of freshly isolated cells remained at 90%, but for short term toxicity studies. the viability of cells post-cryopreservation fell

Table 1 Viability, cytochrome P-450 content and MFO activity in adult human hepatocytes during 14 day cryopreservation period at -80° C in 25% VS Cryopreservation Cytochrome Aminopyrine N- period (days) Viability P450 EROD PROD demethylation 1 67 ± 2 75 ± 5 91 ± 5 101 ± 2 78 ± 1 3 62 ± 3 79 ± 2 98 ± 4 99 ± 3 75 ± 8 5 58 ± 3 77 ± 4 96 ± 8 93 ± 5 75 8 7 54 ± 3* 78 ± 3 94 ± 3 101 ±3 89 11 14 50 ± 3* 72 ± 3 80 ± 2 86 ± 3* 89 5 Values are mean ± s.e. mean of 3-8 experiments and are expressed as a percentage of the fresh cell values. EROD and PROD = ethoxy- and pentoxyresorufin O-dealkylase activity, respectively. *P < 0.05, using one way ANOVA with significance assigned using Dunnett's test.

Rall, W. F. & Fahy, G. M. (1985). Nature, 313, 573. Strom, S. C. et al. (1982). J. Nat. Inst. Cancer, 68, 771.

The effect of azidothymidine (AZT) on pyrine breath test reported an inhibitory effect oxidative drug metabolism in patients with on hepatic n-demethylation. However the dose AIDS required was approximately one hundred times greater than that used in patients. M. BARRY, P. KELLEHER, F. MULCAHY & In this study we investigated the effect of J. FEELY AZT on hepatic oxidative drug metabolism in Department of Pharmacology and Therapeutics, seven male patients (mean age 32 years) with Trinity College Medical School, St James's Hospital, AIDS. Using the [14C]-aminopyrine breath test Dublin 8 (Henry et al., 1979) as an index of oxidative drug metabolism patients with HIV seroposi- Azidothymidine (3-azido, 3-deoxythymidine; tivity and previous Pneumocystis carinii pneu- zidovudine or AZT) is a thymidine analogue monia were studied. They were being treated that inhibits human immunodeficiency virus with prophylactic low dose cotrimoxazole (960 (HIV) replication in vitro. Recent studies sug- mg twice daily) for at least 1 week prior to study gest that AZT administration can decrease to prevent recurrence of pneumonia. Each mortality and the frequency of opportunistic patient was studied before and 3 days after infections in a selected group of patients with commencing AZT 200 mg orally 4 hourly. the acquired immunodeficiency syndrome AIDS Following intravenous administration of 2 ,uCi (Fischl et al., 1987). [14C]-aminopyrine, 2 mmol of exhaled 14C02 Patients in whom AZT has been beneficial was collected in a liquid scintillation vial con- are likely to require other medication including taining 4 ml of 1 M hyamine:ethanol 1:1 (volI multiple and prolonged drug regimens. Con- vol) with phenolphthalein as indicator. Breath comitant treatment with paracetamol was asso- samples were collected at 30 min intervals over ciated with an increased frequency of marrow 4 h. The half-life of 14CO2 was calculated from suppression, the risk increasing with the duration a semilogarithmic plot of the breath specific of administration (Richman et al., 1987). How- activities beyond 2 h. The results are shown ever the potential for possible drug interactions in Table 1. Using a Wilcoxon matched pairs between AZT and concomitant medications is signed rank test there was no significant differ- largely unknown. In an in vivo study in Wistar ence in aminopyrine half-life assessed before rats (Barry et al., 1988) using the 14CO2 amino- and after treatment with AZT. 668P Proceedings of the BPS, 19-21 December 1988 These results indicate that AZT did not at effect on N-demethylation in Wistar rats using this dose impair hepatic N-demethylation to a similar dosages. significant degree in these seven male patients It seems unlikely that AZT will produce sig- with AIDS. This is in agreement with our earlier nificant interactions in man as a result of in- findings (Barry et al., 1988) which reported no hibition of hepatic oxidative drug metabolism.

Table 1 Aminopyrine '4CO2 elimination half-life (h, mean ± s.d.; n = 7) Pre-treatment Post-treatment 7.0 ± 1.7 8.2 ± 3.0

Barry, M. et al. (1988). Br. J. Pharmac. (in press). Henry, D. et al. (1979). Br. J. clin. Pharmac., 8, 539. Fisch, M. A. et al. (1987). New Engl. J. Med., 317, Richman, D. D. et al. (1987). New Engl. J. Med., 185. 317, 192.

Effects of anti-epileptic drugs on thyroid (COMB = 12) took part. Fourteen epileptics hormones and 11 healthy subjects acted as controls. Serum T4, FT4, triiodothyroxine (T3) and J. G. LARKIN*, G. J. A. MACPHEE, thyrotropin (TSH) were measured in all sub- G. H. BEASTALL' & M. J. BRODIE jects. A limited number (minimum 6) in each Clinical Pharmacology Unit, University Department group had a TRH test performed. Results were of Medicine, Western Infirmary and 'Department of compared for individual groups, and for in- Biochemistry, Royal Infirmary, Glasgow ducers (CBZ + PHT + COMB) vs VPA vs controls (healthy + epileptic) using Kruskal- Anticonvulsants are known to decrease serum Wallis and Mann-Whitney U tests. thyroxine (T4) concentrations (Oppenheimer et Results of the individual groups are shown in al., 1961) although the mechanism and clinical Table 1. Taken together, induced patients had significance remain uncertain. Displacement lower T4 and FT4 levels than controls (P < from binding proteins may contribute to the 0.001, P < 0.05) and VPA patients (P < 0.001, effect, but fails to explain reduced free thyroxine P < 0.002). No significant differences were (FT4). Larsen et al. (1970) suggested enhanced found in T3 and TSH results. Nine patients with clearance due to enzyme induction as a T4 below normal (55-144 nmol l-1) were all mechanism. Sodium valproate (VPA) differs taking inducing drugs. No subject had a 'hypo- from other anticonvulsants in its failure to induce thyroid' TRH test. hepatic monoxygenase enzymes (Perucca et al., These results confirm that treatment with 1984). Any difference in its effect on thyroid enzyme-inducing anticonvulsants but not with hormones might thus support the induction VPA is associated with reduced T4 and FI4 theory. concentrations. Although hepatic oxidation is Forty-four epileptic patients taking carbama- not a major centre of T4 metabolism, induction zepine (CBZ n = 19), phenytoin (PHT n = may enhance a 'wastage pathway'. 13), VPA (n = 10) or a combination of drugs Proceedings of the BPS, 19-21 December 1988 669P

Table 1 Mean (± s.d.) results of thyroid function tests in six subject groups Controls Untreated VPA CBZ PHT Combination (n = 11) (n = 14) (n = 10) (n = 19) (n = 13) (n = 12) T4 (,u.mol 1-1)* 86.6 92.9 99.9 71.6 65.0 65.2 (N 55-144) ±21 +22 +20 ±18 ±21 ±15 FF4 (pmol 11)* 16.4 16.0 18.3 14.3 12.2 12.2 (N 9-25) ±3.5 +5.1 ±2.9 ±3.2 ±4.2 ±2.8 T3 (nmol l-1) 1.71 1.86 1.8 1.76 1.53 1.77 (N 0.9-2.8) ±0.25 +0.28 ±0.39 ±0.2 ±0.34 ±0.37 TSH (mU l-l) 1.26 1.48 1.53 1.5 1.03 1.51 (N 0.35-4) +0.75 ±0.72 ±0.78 ±0.69 ±0.4 ±0.73 *Difference between groups P < 0.01 (Kruskal-Wallis)

Larsen, P. R. et al. (1970). J. clin. Invest., 49, 1266P. Perucca, E. et al. (1984). Br. J. clin. Pharmac., 18, Oppenheimer, J. H. et al. (1961). J. clin. Endocrinol. 401P. Metab., 21, 252P.

Prochlorperazine and its sulphoxide The parent drug kinetic data were fitted to a metabolite simultaneous pharmacokinetic one compartment oral dosing model and the modelling metabolite data were simultaneously fitted to a single metabolite compartment with input from T. C. LI KAM WA, S. H. D. JACKSON, the parent drug compartment. This was per- M. LAWSON, M. J. DENNIS' & G. JAHN' formed using a nonlinear regression analysis Department of Clinical Pharmacology, St Bartholo- program, SIMP, which employs a simplex mew's Hospital, London EClA 7BE and 'Rhone algorithm (Johnston, 1985). Poulenc Ltd, Dagenham, Essex The most impressive findings were the un- expectedly rapid absorption of this formulation Oral absorption of prochlorperazine (P) tablets of P (Table 1) and the relatively higher molar is slow and bioavailability is low with extensive concentrations of metabolite vs parent drug. first pass metabolism (Taylor & Bateman, P could not be detected in one subject because 1987) with the major metabolite almost certainly of an interfering h.p.l.c. peak. PS concentration- identified as the sulphoxide (PS). This study time curves were well described by the kinetic was designed to gain information about the model (Figure 1). The lack of adequate parent pharmacokinetics of a new effervescent formu- drug data in the absorption phase in several lation of P, Stemetil Eff, following oral admin- subjects prevented reliable estimate of absorp- istration of a therapeutic dose of this formulation. tion rate constant being derived. The parent Six healthy male volunteers, aged 20-31 drug hybrid rate constant and metabolite elimi- years, received 2 x 5 mg sachets of Stemetil Eff nation rate constant, however, could be more dissolved in 100 ml of water following an over- precisely estimated and from these, t½l,,z values night fast. Blood samples were taken at 0, 0.5, were calculated (Table 1). 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12 and 24 h after This is the first report of the kinetics of the dosing. The analysis of plasma for P and PS was metabolite of P, which may be relevant, as it is performed using an h.p.l.c. method (Sankey et not known whether the metabolite is active. al., 1982). The limits of detection of the assay This effervescent formulation of P is more for P and PS were 0.13 and 0.26 nmol 1-1 re- rapidly absorbed than the conventional one spectively, and the coefficients of variation (Taylor & Bateman, 1987) and may therefore were < 7.5% for P and < 10% for PS, n = 10. have a faster onset of action. 670P Proceedings of the BPS, 19-21 December 1988 Table 1 Mean ± s.d. kinetic parameters (n = 5) c 7 0 P PS 6 CC.-- 5 tma, (h) 0.9 ± 0.7 3.5 ± 1.2 0 4 Cmax (nmol 1-') 0.6 ± 0.2 4.0 ± 1.7 3 t½ z (h) 5.0 ± 3.0 0.3 ± 0.2 S0E CU 2 ' Co PS 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Time (h) Figure 1 Concentration-time profiles for P and PS (0) together with the modelled curves (-) in one subject.

Johnston, A. (1985). J. Pharmac. Methods., 14, 435. Taylor, W. B. & Bateman, D. N. (1987). Br. J. clin. Sankey, M. G. et al. (1982). Br. J. clin. Pharmac., Pharmac., 23, 137. 13, 578.

The pharmacokinetics of acebutolol in assessed from the acetylsulphadimidine/sulpha- African Negro and White Caucasian dimidine ratio in urine collected 3-6 h following volunteers a 2 g dose of sulphadimidine. The acetylated sulphadimidine was hydrolysed to sulphadimi- K. S. OLIVER, M. J. DENNIS & W. P. P. LEARY' dine which was assayed by h.p.l.c. (Mallett et Biopharmaceutical Research, Rh6ne-Poulenc Ltd, al., 1988) and compared with non-hydrolysed Dagenham, Essex and 'Department of Clinical Phar- urine. macology, University of Natal Medical School, The Cmax values for acebutolol in Negroes Durban, S.A. were statistically significantly higher than in White Caucasians (Table 1). There were no Acebutolol is a cardioselective 1-adrenoceptor significant differences in AUC or the terminal blocking drug. Its major metabolite, diacetolol, elimination half-life (t½) which implies that has a similar pharmacodynamic profile to ace- there are some racial differences in the rate of butolol. Odia & Cole (1986) reported that ace- absorption or distribution of acebutolol, but not butolol along with other 13-adrenoceptor in elimination. Acetylator status did not affect blockers is less effective in Negro patients when acebutolol disposition, supporting the findings compared with White Caucasian patients. The of Gulaid et al. (1978), who did not find a cor- aim of-the study was to look for differences in relation between acetylator status and diacetolol metabolism and pharmacokinetics of acebutolol production from acebutolol. It is likely that the due to race and acetylator status. rate-determining step in acebutolol disposition Eighteen healthy male volunteers (nine Negro, in the hydrolysis of acebutolol to the amine nine White, aged 19-35 years) received a single metabolite which is then acetylated rapidly to 400 mg tablet of acebutolol. Blood and urine diacetolol. These data indicate that racial dif- samples were taken prior to dosing and up to ferences in pharmacological response to ace- 24 h post-dose. Plasma was assayed by modifi- butolol between White Caucasians and Negroes cation of an h.p.l.c. method (Holt et al., 1981). are not due to poor absorption or increased The acetylator status of each volunteer was elimination in Negroes. Proceedings of the BPS, 19-21 December 1988 671P

Table 1 Acebutolol Diacetolol Amine metabolite White Negro F.A. S.A. White Negro F.A. S.A. White Negro F.A. S.A. Cmax (ng ml-') 401 555 459 496 531 672 588 529 156 186 169 176 tmax (h) 3.1 2.7 3.0 2.5 3.6 4.0 3.9 3.5 5.0 2.9 4.2 3.0 t½/2 (h) 2.5 2.6 2.7 2.1 9.1 7.6 8.1 9.3 N.D. N.D. N.D. N.D. AUC (p.g ml-' h) 1.9 2.3 2.2 1.9 6.9 6.6 6.9 6.4 0.82 1.6 0.83 2.5 S.A. = Slow acetylator (14 out of 18 volunteers) F.A. = Fast acetylator (4 out of 18 volunteers, all Negroes) N.D. = Not determined-insufficient data points

Gulaid, A. A. et al. (1978). Br. J. clin. Pharmac., 5, Mallett, D. M. et al. (1988). J. Chrom. Biomed. Appl., 261. 428, 190. Holt, J. E. et al. (1981). Br. J. clin. Pharmac., 12, Odia, 0. J. & Cole, T. 0. (1986). Curr. Ther. Res., 282P. 40, 680.

The effect of food on the pharmacokinetics period was allowed between treatments. Venous of halofantrine in man after the admin- blood (10 ml) was taken predose and at 0.5, 1, istration of a single oral dose 2, 3, 4, 6, 8, 10, 12, 24, 48, 72 and 168 h post dose. Plasma Hf and Hfm were determined by K. A. MILTON', G. EDWARDS"2, S. A. WARD2, h.p.l.c. (Milton et al., 1988). Peak plasma con- M. L'E. ORME & A. M. BRECKENRIDGE' centrations of Hf (Cmax) and the times at which 'Department of Pharmacology and Therapeutics, these were attained (tmax) were obtained by University of Liverpool, Liverpool L69 3DX and visual inspection of the log plasma concentra- 2Department of Parasitology, Liverpool School of tion vs time profiles. Areas under the curve to Tropical Medicine, Liverpool L3 SQA infinity (AUC) for Hf and Hfm were obtained by the trapezoidal rule. Individual values for Hf Halofantrine (Hf) is a new phenanthrene are given in Table 1. methanol derivative effective in the treatment Three way ANOVAR indicated significant of multi-drug resistant Plasmodium falciparum increases in Cmax (P S 0.01) and AUC (P - malaria (Cosgriff et al., 1982). Presently, only 0.05) and a significant (P < 0.05) reduction in the hydrochloride salt (Hf.HCl) is in clinical tmax when the drug was administered with food. use. This is highly insoluble in water and conse- Mean (± s.d.) AUC values for Hfm were in- quently it is believed that Hf is incompletely creased significantly (P - 0.05) from 5.6 ± 3.8 and erratically absorbed from the G.I. tract. x 103 ,ug 1-1 h (FA) to 11.5 ± 3.8 x 103 ,ug F-1 We have evaluated the effect of a relatively h (FD). These findings would suggest that diet fatty meal on the pharmacokinetics of Hf.HCl may have profound effects on the pharmaco- and desbutylhalofantrine (Hfm) in healthy sub- kinetics of Hf and its major plasma metabolite, jects in an open randomised crossover study. Hfm. Their importance in malaria chemo- Local ethics committee approval and written therapy remains to be established. informed consent were obtained. Six male volunteers each received a single dose of Hf This work was supported by funds from SK & F hydrochloride (250 mg) administered in the Research Ltd. KAM is in receipt of a studentship fasted state and with a standardised breakfast from the Research Development Fund of the Univer- containing 60 g fat. A one month wash out sity of Liverpool. SAW is a Wolfson Lecturer. 672P Proceedings of the BPS, 19-21 December 1988

Table 1

Cmax (yg I) tma (h) AUC (,ug 1-1 g x 103) Subject FA FD FA FD FA FD 1 217 853 6 4 5.2 14.6 2 392 1178 6 6 8.6 8.8 3 181 534 8 3 3.0 7.4 4 140 1565 4 2 2.7 9.5 5 65 1787 6 2 1.5 16.4 6 111 1390 6 3 2.5 10.8 FA fasting, FD food

Cosgriff, M. T. et al. (1982). Am. J. Trop. Med. Milton, K. A. et al. (1988). J. Chromatogr., 433, 339. Hyg., 31, 1075.

An interlaboratory comparison of tech- Abbott TDX 1.4, RIA 3.3, Ames TDA 4.2, Syva EMIT 6.3 niques for the measurement of digoxin in serum Underlined techniques were not significantly different (P > 0.05, chi-square). J. F. WILSON, L. M. TSANACLIS, J. WILLIAMS, A comparison of the coefficient of variation J. E. TEDSTONE & A. RICHENS of measurements for samples with spike values Department of Pharmacology and Therapeutics, below, within and above the therapeutic range University of Wales College of Medicine, Cardiff CF4 (Table 1) showed Ames TDA and Syva EMIT 4XN to be less precise than the other techniques for measurements of digoxin concentrations The accuracy and precision of three non-isotopic < 1 nmol 1-1 (P < 0.05, two-way analysis of assay techniques and of radioimmunoassay variance). (RIA) were compared using data from 141 A comparison of the accuracy of measure- samples of digoxin spiked human serum from ments for different concentration ranges (Table the Heathcontrol external quality assurance 2) showed a small negative bias for Ames TDA scheme. Samples were assayed for digoxin by within the therapeutic range. A concentration between 21 and 52 laboratories in 1984-1987. related variation in accuracy was demonstrated Data were screened to remove measurements for Abbott TDX. There was a significant linear more than three standard deviations from the regression between the percentage difference of sample mean (Healy, 1979). The frequency of the sample mean from the spike value against these outliers differed significantly (P < 0.001, the spike value (P < 0.001) owing to positive chi-square) between the four technique groups, bias at low and negative bias at high digoxin the percentages of rejected measurements being: concentrations (Table 2).

Table 1 Mean coefficient of variation (%) of measurements of digoxin made by different techniques for different concentration ranges Technique < I nmol i-l 1-2.6 nmol l1- > 2.6 nmol l-1 Abbott TDX 21.1 ± 1.6 (31) 10.0 ± 0.5 (77) 6.4 ± 0.4 (33) Ames TDA 28.7 ± 15.6 (10) 8.8 ± 1.4 (40) 7.6 ± 1.2 (19) Syva EMIT 28.4 ± 5.4 (15) 12.9 ± 1.5 (55) 10.0 ± 1.2 (24) RIA 20.8 ± 1.8 (31) 12.2 ± 0.4 (77) 9.4 ± 0.4 (33) Values are mean ± s.e. mean (number of samples) Proceedings of the BPS, 19-21 December 1988 673P

Table 2 Mean percentage difference between sample mean and spike value for digoxin measurements made by different techniques for different concentration ranges Technique < I nmol 1-1 1-2.6 nmol 1-1 > 2.6 nmol 1-' Abbott TDX 13.9 ± 4.0 (31)* -0.7 ± 1.6 (77) -6.7 ± 1.8 (33)* Ames TDA -0.4 ± 5.0 (10) -4.0 ± 1.9 (40)* -2.1 ± 2.0 (19) Syva EMIT 1.6 ± 5.1 (15) 0.4 ± 2.1 (55) -1.9 ± 2.4 (24) RIA -0.5 ± 2.5 (31) 0.9 ± 1.4 (77) -0.1 ± 1.9 (33) Values are mean ± s.e. mean (number of samples) * indicates mean significantly different from zero (P < 0.05, t-test)

Healy, M. J. R. (1979). Clin. Chem., 25, 675.

The pharmacokinetics of intravenous stable 12, 14 and 20 days after the beginning of the strontium in healthy volunteers infusion. Urine samples were collected every 24 h during the same period. Plasma and urinary M. E. AMARAL DE MORAES, J. K. ARONSON strontium concentrations were measured by & D. G. GRAHAME-SMITH atomic absorption spectrophotometry with MRC Unit and University Department of Clinical graphite furnace. The plasma concentration vs Pharmacology, Radcliffe Infirmary, Oxford OX2 6HE time data for each subject were analysed into three exponentials using NONLIN and model- Strontium is an element whose distribution in independent calculations were made on the basis the body is similar to that of calcium, and radio- of the results. The pharmacokinetic variables active strontium has been used to study calcium thus obtained are shown in Table 1. metabolism in man (Reeve et al., 1983). How- These data show that the terminal half-life ever, studies of the pharmacokinetics of stable of stable strontium in healthy subjects is much strontium in man have been few in number and longer than the previously reported value of 2 limited in duration (Eisenberg & Gordan, 1961; days, and this has been elucidated because we Root et al., 1966). We have therefore studied have sampled for 20 days (about four half-lives) the pharmacokinetics of stable strontium given after administration. The clearance of strontium intravenously to healthy volunteers, with plasma from the body is mainly by the renal route (57%), and urinary concentration measurement for and the low rate of renal clearance suggests that 20 days, in order to extend the information strontium is subject to a high degree of passive currently available, with the intention of using reabsorption in the renal tubules. The apparent strontium as an in vivo marker of calcium dis- volume of distribution (Vs5) is similar to the size position in future studies. of the exchangeable pool (56.9 1) reported by After collecting control plasma and urine others (Root et al., 1966). samples for the measurement of endogenous Since the pharmacokinetics of stable strontium strontium concentrations in 10 healthy men may be useful as an in vivo marker of calcium (19-55 years, 69-100 kg), we gave each volun- disposition, we are currently studying the effect teer 5 mmol of strontium gluconate by i.v. in- of the calcium antagonist nifedipine on the fusion over 1 h. Blood samples were taken at pharmacokinetics of stable strontium. 1, 2, 3, 4, 5, 6 and 8 h, and 1, 2, 3, 4, 6, 8, 10, Table 1 The pharmacokinetics of stable strontium after the intravenous administration of 5 mmol strontium gluconate to 10 healthy men. The data are shown as mean (s.d.) t, CL CLR VZ V. (days) (ml min-) (ml min-') (1) (1) 5.37 9.38 5.39 97.4 63.9 (2.65) (2.99) (1.56) (42.6) (22.2) 674P Proceedings of the BPS, 19-21 December 1988

Eisenberg, E. & Gordan, G. S. (1961). J. clin. Invest., Root, A. W. et al. (1966). J. clin. Endocrinol., 26, 40, 1809. 537. Reeve, J. et al. (1983). Calcif. Tissue Int., 35, 9.

Pharmacokinetics of tacrine hydrochloride in patients with dementia The peak serum concentrations of THA after oral administration of both 25 mg and 50 mg D. R. FORSYTH, R. MORGAN, C. A. TRUMAN, occurred within 1.5 h. Thereafter there was a J. M. FORD, G. K. WILCOCK & bi-exponential decay. The elimination half-life C. J. C. ROBERTS after 50 mg was significantly longer than that Department of Medicine, University of Bristol, Bristol after 25 mg (P < 0.01) and the AUC(O,oo) after 50 mg was greater than the AUC(O,oo) after 25 Tacrine hydrochloride (THA) is a centrally- mg multiplied by 2 (P < 0.08) (see Table 1). acting reversible cholinesterase inhibitor which The maximum serum concentrations of the is under investigation as a treatment for Alz- metabolite after oral administration of both heimer's disease (Summers et al., 1986). The 25 mg and 50 mg of THA coincided with those aim of the study was to characterise the drug's of THA. Thereafter the concentrations fell pharmacokinetics in patients. Four male and mono-exponentially. The half-life of the meta- four female patients with the condition aged bolite after the 50 mg dose was longer than 58-86 years who had been recruited into a that after the 25 mg dose (P < 0.05) and the clinical trial of the drug were studied. Informed AUC(O,o) after 50 mg was greater than the consent was obtained from their carers. None AUC(0, o) after 25 mg multiplied by 2 (P < was suffering from renal or hepatic impair- 0.01). The results following i.v. administration ment and any drug therapy had been dis- are shown in Table 2. Note that the ratio of continued for 3 weeks. After an overnight-fast AUC(metabolite):AUC(THA) is considerably a 25 mg capsule of THA was administered orally lower than that after oral administration. at 08.00 h. Venous blood samples were taken The study has described the pharmacokinetic at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 16 and 24 h. parameters of THA. It appears to be a drug Three days later six of the patients repeated the with high clearance and low bioavailability. The study after the administration of 50 mg orally low bioavailability may be related to the pro- and subsequently two patients were studied duction of a metabolite during presystemic after either 3 mg or S mg intravenously. Serum metabolism. The results also suggest that the samples were frozen at -20° C and THA con- pharmacokinetics of THA may be dependent centration together with its postulated meta- on dose. bolite assayed by the method of Forsyth et al. (1988).

Table 1 Pharmacokinetics of THA and postulated metabolite following oral administration (mean ± s.e. mean) Elimination A UC(O, 00) Elimination A UC(O, oo) Dose Number half-life of THA half-life metabolite (mg) ofpatients THA (h) (ng ml-' h) ofmetabolite (h) (ng ml-' h) 25 8 1.59 ± 0.15 29.0 ± 6.07 3.56 ± 0.28 59.6 ± 10.0 50 6 2.14 ± 0.24 83.2 ± 26.76 4.11 ± 0.36 142.6 ± 25.0

Table 2 Pharmacokinetic data in two patients who received THA both orally and intravenously Volume of Plasma Intravenous Elimination distribution clearance Bioavailability Ratio AUC(metab):AUC(THA) dose (mg) half-life (h) (1) (ml min-') (%) 25 mg oral 50 mg oral i. v. 3 1.25 68.2 631 2.4 3.7 3.5 0.041 5 2.23 168.0 871 3.1 4.0 5.6 0.038 Proceedings of the BPS, 19-21 December 1988 675P Forsyth, D. R. et al. (1988). J. Chromatogr. (in Summers, W. K. et al. (1986). New Engl. J. Med., press). 315, 1241.

Effect of 3-carboxy-4-methyl-5-propyl-2- the addition of the inhibitor at concentrations furanpropanoic acid on the binding of between 10 and 60 ,UM. The effects of 5-propyl fluorescent probes to human albumin FPA, 5-pentyl FPA and phenylbutazone on the binding of the probes to albumin were also C. E. BARKER & W. E. LINDUP measured by equilibrium dialysis. Department of Pharmacology and Therapeutics, The fluorescence produced by DNSA was University of Liverpool, P.O. Box 147, Liverpool decreased by both furanoid acids and by the L69 3BX two reference drugs phenylbutazone and war- farin (Table 1). The decreases produced by 5- 3-Carboxy-4-methyl-5-propyl-2-furanpropanoic propyl FPA and phenylbutazone were similar acid (5-propyl FPA) accumulates in uraemic and were greater than those in the presence plasma (Mabuchi & Nakahashi, 1988) and is an of either 5-pentyl FPA or warfarin (Table 1). inhibitor of drug binding (Lindup et al., 1986; These four ligands also inhibited the binding of Mabuchi & Nakahashi, 1988; Niwa et al., 1988). dansylsarcosine but with the exception of 5- Two drug binding sites or regions of human pentyl FPA the effect was much less. Equili- albumin have been distinguished by the use of brium dialysis confirmed that the decrease in the fluorescent probes dansylamide (site I; war- fluorescence was related to a decrease in the farin) and dansylsarcosine (site II; diazepam). binding of the two probes. The effects of 5-propyl FPA and its analogue The results indicate that although 5-propyl 5-pentyl FPA on the binding of these two FPA is a stronger inhibitor of binding to site I fluorescent probes to human albumin have than to site II, the 5-pentyl analogue can inhibit therefore been investigated to see if they have quite strongly at site II. It appears therefore any selective inhibitory effects. that the furanoid acids are likely to affect bind- Binding of the fluorescent probes to human ing to at least two sites on human albumin in albumin was measured by the method of Sud- uraemic plasma. low et al. (1975). The fluorescence of solutions containing probe (2 FM) and human albumin This work was supported by Mersey Regional Asso- (20 FM) in phosphate buffer pH 7.4 was measured ciation for Kidney Research. at the appropriate wavelengths before and after

Table 1 Inhibitory effect of 5-propyl- and 5-pentyl FPA, phenylbutazone and warfarin on the binding of dansylamide (DNSA) to human albumin measured by fluorescence spectroscopy % Decrease in fluorescencea ofDNSA at inhibitor: albumin ratios of: Inhibitor 1:1 2:1 3:1 5-Propyl FPA 61 70 73 5-Pentyl FPA 27 42 48 Phenylbutazone 50 68 75 Warfarin 35 39 43 aAlbumin concentration 20 AM; DNSA concentration 2 AiM.

Lindup, W. E. et al. (1986). In Protein binding and Mabuchi, H. & Nakahashi, H. (1988). Nephron, 49, drug transport, eds Tillement, J.-P. & Linden- 277. laub, E., pp. 397-414. Stuttgart-New York: Niwa, T. et al. (1988). Clin. Chim. Acta, 173, 127. F. K. Schattauer Verlag. Sudlow, G. et al. (1975). Mol. Pharmac., 11, 824. 676P Proceedings of the BPS, 19-21 December 1988 The effect of propranolol on buccal B.p.d. was recorded using the method of Huston potential difference (1978). After rinsing the mouth with 20 ml dis- tilled water the b.p.d. was measured at 30 s A. MAKEDOU, A. HEDGES & P. TURNER intervals for 3 min (pre-treatment). Treatments Department of Clinical Pharmacology, St Bartholo- were prepared in 20 ml citric acid/phosphate mew's Hospital, London, EClA 7BE buffer (pH 4.5) and swirled around the buccal cavity for 3 min. The mouth was rinsed three Aspirin affects the buccal potential difference times with 20 ml distilled water and b.p.d. (b.p.d.) in man by making it- less negative measured for 3 min as before (post-treatment). (Huston, 1978). We are investigating the in- The difference in mean b.p.d. pre- and post- fluence of this effect on buccal absorption of treatments was analysed statistically using weak bases. The present study was designed to Student's paired t-test. compare the effects of aspirin, propranolol and The rise in b.p.d. after aspirin in this study is placebo on b.p.d. in man. This was necessary lower than in some other studies where values to exclude an influence of propranolol on b.p.d. after 600 mg of aspirin were 26.0 mV (Shah et before using it in a study on the effect of al., 1986). This was due in part to a single changing b.p.d. on its absorption. subject who showed no effect of aspirin, and is Eight healthy volunteers with no known sen- responsible for the large s.d. of mean values sitivity to aspirin received placebo, propranolol after aspirin (Table 1). We have found no effect 4 ,ug, propranolol 4 mg and aspirin 600 mg, of propranolol at either concentration. single-blind, according to a 4 x 4 Latin square.

Table 1 Mean changes in b.p.d. in eight subjects Mean (95% CI) of Drug Change in b.p.d. (mV) differencefrom placebo Placebo -2.0 Propranolol 4 jig 6.5 -7.4, 15.9 Propranolol 4mg 4.4 -3.1, 16.0 Aspirin 600 mg 16.4* -2.1, 34.8 *Significantly different from placebo P < 0.005

Huston, G. J. (1978). Br. J. clin. Pharmac., 5, 155. Shah, K. etal. (1986). Br. J. clin. Pharmac., 21, 113P.

Analysis of concentration ratios in paired t) and CR (t) = REi Ai. exp(-ki t) [Ai, ki are experiments constants] provided that the kinetics are linear. Then each time-point gives an estimate, r(t) = R. E. FERNER*, G. GEORGE & CR (t)/C,(t), of R. If there is a non-linear com- D. R. APPLETON' ponent r(t) becomes increasingly larger than R. Wolfson Unit of Clinical Pharmacology and 'Depart- Since the distribution (Figure 1) and time-trend ment of Medical Statistics, University of Newcastle (Figure 2) of r(t) can be examined, r(t) can be upon Tyne NE1 7RU used to estimate R when the assumption appears to hold. We have used the method to analyse When different doses of a drug are injected data from subjects given two different intra- intravenously on two occasions into the same venous doses of tolbutamide and compared subject, the ratios of areas under the concen- it with AUC calculated from non-linear least tration-time curve (AUC) may be used as a squares exponential fits. Its robustness is illus- measure of dose-ratio, or to determine if phar- trated by successively deleting (approximately) macokinetics are linear. If samples are taken at alternate observations and recalculating R. In time t on two occasions when doses in the ratio one patient, R estimated from r(t) was 1.87 1:R are injected then the concentrations C, (t) (s.e. mean 0.010), 1.86 (0.093), 1.86 (0.019) and CR (t) are given by C, (t) = EAi.exp(-k, and 1.84 (0.031) using data from 45, 23, 11 and Proceedings of the BPS, 19-21 December 1988 677P 6 pairs of points respectively. R estimated from method is a simple method for estimating dose- the corresponding AUC(O-oo) was 1.72, 1.66, ratios and assessing the linearity of pharmaco- 1.95 and indeterminate. The concentration-ratio kinetics.

Patient GA

1o0

0 CT 0).( 0L

1 . r(t) Figure 1 Distribution of r(t).

Patient GA - - 2.0 .^ . '= 1.8-"_. -. . * . 0 *- 1.6 l l 0 60 120 180 240 300 360 420 Time (min) Figure 2 Time-course of r(t).

Galenic aspects in the assessment of the carbonate + magensium hydroxide scored effect of antacids on the bioavailability of slightly but significantly lower (82%, 95% CI: cimetidine 74 to 90). A further suspension of cimetidine + aluminium hydroxide + magnesium carbonate C. DE MEY, I. MEINEKE, D. ENTERLING & + magnesium hydroxide however had a relative H. WESCHE bioavailability of 92% (95% CI: 84 to 102, n = SK&F-Institute for Applied Clinical Pharmacology, 12), and for swallow tablets of cimetidine with Gottingen, FRG aluminium hydroxide + magnesium hydroxide a bioavailability of 96% (95% CI: 87 to 108) It is often claimed that antacids reduce cimeti- was found, relative to cimetidine-Tagamet dine's systemic bioavailability when admin- tablets, whereas chew tablets had a slightly istered concomitantly or in combination. We lower bioavailability (82%, 95% CI: 74 to 91, assessed cimetidine's plasma and urinary kinetics n = 12). It therefore was suspected that more after acute administration of various cimetidine general galenic and physicochemical aspects + antacid combination products with similar might play a predominant role, rather than the neutralising capacity and found that a negative mere presence of antacids. One of the elements effect on cimetidine's bioavailability by antacids under suspicion was the replacement of sac- cannot be accepted as a general rule. Carbon- charose by sorbitol or mannitol as is often ates for instance tended to have little effect. For undertaken in the development of new formu- a suspension of cimetidine + calcium carbonate lations. In a first study in 12 normal subjects + magnesium carbonate an estimated bioavail- we found Cmax to be reduced (estimated ratio ability of 98% (95% CI:88 to 107, n = 12), was vs reference: 0.66, 95% CI: 0.56 to 0.78), found relative to cimetidine-Tagamet tablets. AUC(0-12) also (estimated ratio: 0.77, 95% In the same study a suspension with calcium CI: 0.68 to 0.88) when the MRT was prolonged 678P Proceedings of the BPS, 19-21 December 1988 (estimated ratio: 1.17, 95% CI: 1.05 to 1.30) Both mannitol containing formulations when saccharose in a cimetidine 200 mg 5 ml-' (B&C) showed tendency towards a longer suspension was replaced by sorbitol. In a further terminal half-life and MRT, and the relative study we looked at three newly developed chew contribution of the 8-24 h urine fraction to the tablets each containing 100 mg cimetidine plus total 0-24 h collection was significantly increased magnesium hydroxide + magnesium carbonate in both. This might mean that mannitol affects + aluminium hydroxide. One formulation also both the absorption extent of cimetidine (AUC contained 670 mg saccharose (A), in the second and 'total urinary recovery') and the absorption (B), saccharose was replaced by 662 mg sorbitol, rate (MRT, urinary recovery rate and terminal to which in the last formulation (C), 20 mg soya slope), of which only the former is 'corrected' lecithin was added. Single doses of 200 mg were by adding soya lecithin. These and further administered in a period-balanced cross-over galenic aspects are to be taken into account study design (study days at least 1 week apart) when the potential impact of further constituents which included a single 200 mg cimetidine-tablet are assessed on the bioavailability of drugs that as reference (R). The treatment contrasts (geo- are administered via complex formulations. metric means of ratios vs R, or differences of the means vs R) are summarised in Table 1 (+95% CI).

Table 1 Parameter AIR BIR CIR AUC(0-i) 0.98 (0.88, 1.08) 0.80 (0.72, 0.89) 1.00 (0.90, 1.11) Term. slope 0.89 (0.73, 1.08) 0.78 (0.73, 1.08) 0.70 (0.57), 0.85) Ae((-24) 0.97 (0.83, 1.14) 0.82 (0.70, 0.97) 0.99 (0.84, 1.17) A-R B-R C-R Cmax (ng ml-') -0.16 (-0.35, 0.02) -0.42 (-0.60, -0.24) -0.17 (-0.35, 0.01) MRT (h) 0.33 (-0.13, 0.80) 0.74 (0.27, 1.20) 0.66 (0.20, 1.13)

Pharmacokinetic analysis of perindoprilat to 96 h after infusion, using least squares non- infusions in normal subjects linear regression with the program BMD-PAR on an ICL 3980 computer and a weighting R. J. MacFAYDEN, K. R. LEES, scheme of 1/concentration. The models fitted to J. P. DEVISSAGUET' & J. L. REID each data set included one (A), two (B) and University Department of Materia Medica, Stobhill three (C) compartment open models with zero General Hospital, Glasgow G21 3UW, and 'Labora- order input, and one compartment models with toire de Biopharmacie, Centre d'Etudes Pharma- nonlinear tissue binding (D), plasma binding ceutiques, 92296 Chatenay-Malabry, France (E) or combined nonlinear tissue and plasma binding (F). The fitted residual sums of squares Although the pharmacokinetics of ACE in- (WRSSQ) were compared using F-ratios and by hibitors can be described by multi-compartmental the Schwarz criterion. The Schwarz values were models, it is accepted that protein binding in- subjected to Friedman 2-way ANOVA by ranks fluences the plasma concentration-time profile and Chi squared tests. (Till et al., 1984) and that this can be accounted In the low dose study, F was the most com- for in suitable pharmacokinetic models (Francis plex model which could be supported statistically. et al., 1987). The present communication de- The higher dose study did not support F and scribes i.v. infusion of perindoprilat 1 mg (16 although E was better than B on direct com- subjects) and 6.1 mg (22 subjects) to explore parison (P < 0.005) within the multiple com- the effect of dose on the choice of optimum parisons this was not evident. Thus in the high model. dose study, although E and F described the data A hierarchy of pharmacokinetic models was slightly better than B they offered no significant fitted to serum perindoprilat data obtained up advantage over the standard two compartment Proceedings of the BPS, 19-21 December 1988 679P model. The three compartment model was not and that after low doses the effect of tissue justified. This was supported by much higher binding is also apparent. Since orally admin- coefficients of variation for the parameter esti- istered drug rarely achieves such high concen- mates with model C. trations as were studied here, the effect of tissue We conclude that it is possible to model the binding may be even more evident in clinical pharmacokinetics of perindoprilat after i.v. practice. infusion in terms of nonlinear protein binding

Table 1 Model comparison by Schwarz (NS differences bracketed) 1 mg study (n = 16) A C B E D F WRSSQ (mean) 26.7 17.8 17.7 18.1 10.4 4.6 Schwarz (mean) 73.5 66.0 63.7 63.6 48.3 35.7 Rank sum 80.0 76.0 56.0 55.5 43.0 25.5 x2 = 37.6 L I P < 0.0001

6.1 mgstudy (n = 22) A D B C F E WRSSQ (mean) 111.6 95.9 53.0 46.0 48.3 52.5 Schwarz (mean) 95.6 91.3 79.0 77.2 76.6 77.8 Rank sum 131 105 69 57 54 46 x2 = 37.6 I p < 0.0001 l

Frances, R. J. et al. (1987). J. cardiovasc. Pharmac., Till, A. E. et al. (1984). Biopharm. Drug. Dispos., 5, 9, 32. 273.

Effects of UK-52,046, an oxl-adrenoceptor changes in HR and BP associated with changes antagonist, on baroreflex sensitivity in man in posture. Six healthy male volunteers age 21.7 ± 0.3 J. P. McKAIGUE, D. W. G. HARRON, years (mean ± s.e. mean), weight 72.2 ± 3.0 J. G. RIDDELL & R. G. SHANKS kg received in a double-blind randomised Department of Therapeutics and Pharmacology, The manner at weekly intervals UK-52,046 0.4 ,ug Queen's University of Belfast, Belfast kg-1, prazosin 0.25 mg and placebo i.v. BP was measured from the radial artery and recorded UK-52,046 (4-amino-6, 7-dimethoxy-2-(1,2,3,4- synchronously with the ECG on a chart recorder. tetrahydro-6,7-dimethoxyisoquinol-2-yl)quin- Prior to and 30 min after administration of each oline methanesulphonate), is an a1-adreno- treatment, BP and HR responses to i.v. boluses ceptor antagonist, which reduced arrhythmias of phenylephrine (PE) (20, 50, 100, 200, 300, in experimental models with minimal effects on 400 and 600 pLg) to increase systolic BP by 30 heart rate (HR) and BP (Uprichard et al., 1988). mmHg were measured. The subjects then stood In a previous i.v. dose ranging study in man up; HR and BP were measured at 5 s and at 3 (Harron et al., 1989), UK-52,046 was found to min standing. Linear regression analysis of the have no effects on heart rate (HR) or BP at 0.4 BP and associated R-R intervals (ms) in re- ,ug kg-1, a dose which produces (P < 0.05) al1- sponse to PE was performed and a value for adrenoceptor antagonism to increases in BP slope obtained (AR-R ms/mmHg). Results with phenylephrine (Schafers et al., 1989). were compared using the Friedman two-way Prazosin 0.25 mg i.v. also produces a1-adreno- ANOVA and Student's t-test. ceptor antagonism and exerts no effect on There were no significant changes in supine supine HR or BP (Morganti et al., 1981). systolic BP or HR at 30 min following UK- The present study investigated the effects of 52,046 (108.8 ± 3.3 mmHg, 64.0 ± 4.0 beats UK-52,046, prazosin and placebo on baroreflex min-') or prazosin (105.0 ± 3.8 mmHg, 64.3 ± sensitivity (BRS) (AR-R ms/mmHg) and on 4.5 beats min-1) compared with placebo (111.8 + 680P Proceedings of the BPS, 19-21 December 1988 5.4 mmHg, 63.3 ± 3.6 beats min-). UK-52,046 prazosin 0.25 mg and UK-52,046 0.4 pug kg-l, had no effect on BRS or standing HR and BP; doses which produce blockade of peripheral in contrast, prazosin reduced (P < 0.05) BRS ol-adrenoceptors but which have no effect on and standing BP and increased (P < 0.05) supine HR or BP, produce different effects on standing HR (Table 1). baroreflex sensitivity and standing HR and BP. In conclusion, this study demonstrates that

Table 1 Phenylephrine Standing SBP Standing R-R Standing SBP Standing R-R Slope 5 s 5 s 3 min 3 min Placebo Before 13.4 ± 2.2 92.5 ± 4.7 577 ± 27 112.7 ± 7.7 651 ± 35 After 17.9 ± 2.7a 82.7 ± 5.6 565 ± 23 98.7 ± 11.1 687 ± 49 UK-52,046 Before 13.5 ± 3.1a 97.8 ± 1.4 566 ± 16 108.2 ± 6.0 652 ± 30 After 12.7 ± 1.3b 84.2 ± 7.7 539 ± 20 103.3 ± 6.8 564 ± 42 Prazosin Before 16.6 ± 1.8 96.0 ± 2.9 584 ± 26 110.3 ± 6.2 658 ± 36 After 9.9 ± 1.5t* 69.7 ± 7.6* 541 ± 27 65.5 ± 11.74* 519 ± 17t* a n = 4 b n = 5 t P < 0.05 vs placebo, * P < 0.05 Before vs After, t P < 0.05 vs UK-52,046

Harron, D. W. G. et al. (1989). Br. J. clin. Pharmac., Schafers, P. F. et al. (1989). Br. J. clin. Pharmac., 27, 27, 682P. 102P. Morganti, A. et al. (1981). Clin. Sci., 61, 307s-309s. Uprichard, A. C. G. et al. (1988). Br. J. Pharmac., 95, 1241.

Effects of intravenous and oral UK-52,046, a randomised double-blind manner at 30 min an al-adrenoceptor antagonist, on heart intervals. Supine and standing blood pressure rate and blood pressure in man (BP) and heart rate (HR) were recorded before, following each dose, and after the last dose at D. W. G. HARRON, J. P. McKAIGUE, 1, 2, 3, 4 and 24 h. The results indicated that M. T. BURKE, J. G. RIDDELL, R. G. SHANKS supine and standing systolic BP and HR 10 min & D. COX1 after the cumulative dose of 0.8 ,ug kg-' of UK- Department of Therapeutics and Pharmacology, The 52,046 were (101.7 ± 3.5 mmHg, 61.3 ± 3.8 Queen's University of Belfast, Belfast and 'Pfizer beats min-') and (96.0 ± 4.4 mmHg, 100.7 + Central Research, Sandwich, Kent 8.3 beats min-t) respectively. The correspond- ing values for placebo were supine (106.0 ± 4.4 UK-52,046 (4-amino-6, 7-dimethyxy-2-(1,2,3,4- mmHg, 58.8 ± 4.9 beats min-) and standing tetrahydro-6, 7-dimethoxyisoquinol-2-yl)quino- (104.3 ± 6.0 mmHg, 86.8 ± 6.0 beats min-). line methanesulphonate), decreases ventricular No significant differences (ANOVA) on HR and arrhythmias in experimental models, with mini- BP occurred between placebo and UK-52,046 mal peripheral a1-adrenoceptor antagonist during the course of the study. activity (Uprichard et al., 1988). The present In the second study six healthy male volun- study investigated the peripheral effects of UK- teers age 22.8 ± 0.5 years, weight 76.2 ± 3.8 52,046 in man using similar i.v. doses, in addition kg received single oral doses of UK-52,046 to an oral dose ranging study, in two groups of (0.025, 0.05, 4 x 0.025, 0.1, 0.25 and 0.5 mg) healthy volunteers. in an escalating fashion, with random admin- In the first study six healthy male volunteers istration of placebo. Treatments were at weekly mean age 27.3 (± 3.9 s.e. mean) years, weight intervals, and the study was double-blind. In an 69.5 ± 2.9 kg received four cumulative i.v. open continuation, four subjects received 1 mg doses of UK-52,046 (0.1, 0.1, 0.2 and 0.4 ,g and two continued to 2 mg. Supine and standing kg-') and placebo (treatments 1 week apart) in HR and BP were recorded before and at 1, 2, Proceedings of the BPS, 19-21 December 1988 681P 4, 6, 8 and 24 h after each treatment. Results 94.5 ± 7.3). In the four subjects administered were analysed using ANOVA and Student's t- 1 mg UK-52,046, standing systolic BP and HR test. Maximum changes in HR and BP occurred at 6 h were 99.5 ± 8.0 mmHg and 117.5 ± 8.3 at 4-6 h. There were no significant changes in beats min-1 respectively; corresponding values HR or BP following doses of UK-52,046 up to for placebo were (106.0 ± 4.9 mmHg, 94.5 ± and including 0.1 mg. At 4 h, standing systolic 7.3 beats min-1). Two subjects received 2 mg BP for 0.25 mg (97.7 ± 4.9) and 0.5 mg (98.7 UK-52,046, which produced marked changes + 4.3) was not significantly different from in standing systolic BP (67.0 ± 23.2) and HR placebo (102.7 ± 5.3); standing HR for both (122.0 ± 2.0). 0.25 mg (95.8 ± 7.8) and 0.5 mg (95.5 ± 9.2) These results indicate that i.v. UK-52,046, increased (P < 0.05) compared with placebo at doses which are antiarrhythmic in animals, (86.0 ± 9.3). At 6 h, standing systolic BP for exerts only minimal effects on blood pressure 0.5 mg (95.7 ± 3.6) was reduced (P < 0.05) and heart rate in man. The oral formulation was compared with placebo (106.0 ± 4.9); standing well tolerated in single doses up to 1 mg although HR for both 0.25 mg (110.3 ± 8.4) and 0.5 mg effects on BP and/or HR were observed at doses (105.0 ± 9.8) were increased (P < 0.05) (placebo ¢ 0.25 mg.

Uprichard, A. C. G. etal. (1988). Br. J. Pharmac., 95, 1241.

ADP induced fibrinogen receptor exposure fugation of 50 ml whole blood in the presence on human platelets during the menstrual of 0.053 FLM PGI2. A mixture of 125I-Fb and cold cycle purified Fb (6-200 ,ug ml-') was incubated for 15 min with GFP(1-2 x 108/ml) and 10 M ADP J. FURNISS, R. MISTRY & D. B. BARNETF in a final volume of 1 ml HBMT pH 7.5 contain- Department of Pharmacology and Therapeutics, ing 2% BSA, 1 mm Mg++ and 10 FLM Ca". Clinical Sciences Building, Leicester Royal Infirmary, Non-specific (unactivated) binding was measured Leicester, LE2 7LX in parallel tubes in the presence of 5 mm EDTA to chelate Ca++. Incubation was terminated The final common pathway for aggregation is by centrifugation through oil and radioactivity the exposure of so-called fibrinogen (Fb) 're- bound to the platelet pellet measured by gamma ceptors' on the platelet surface. This is asso- counter. Maximum binding capacity (Bmax) and ciated with a conformational change in specific affinity constant (Kd) of 125I-Fb were measured membrane glycoproteins (GPIIb, lIIa) and can by saturation analysis. Results are expressed as be quantified using binding of 125I-Fb (Mar- mean ± s.e. mean. guerie et al., 1980). We have measured ADP All normal cycles studied were ovulatory as induced 125I-Fb binding to human platelets evidenced by 21 day serum progesterone levels during the menstrual cycle as a possible source > 30 nmol I-'. 125II-Fb binding Kd (0.13 F±M) was of physiological variability to the Fb receptor similar to previous reports (Marguerie et al., similar to that reported for the platelet a2- 1980) and to that found in our hands for Fb adrenoceptor (Jones et al., 1983). supporting ADP induced aggregation in GFP Ten healthy female volunteers (age 21 to 41 (0.29 FJM). Bma results are shown in Table 1. years) with normal regular menstruation (cycle There was considerable interindividual varia- length 26 to 32 days) were studied on days 7, tion between subjects in both study groups. 14 and 21 of the cycle and on day 1 of next A trend towards increasing Fb binding at the menstruation. Three other age matched sub- end of the normal cycle was seen but there were jects taking a low dose oestrogen/progesterone no significant differences between or within the combined oral contraceptive were similarly groups on any cycle day. These data do not studied for comparison. On each study day indicate an important effect of the norml men- washed platelets were prepared by gel filtration strual cycle on platelet Fb receptor exposure to (GFP) of platelet rich plasma derived by centri- ADP. 682P Proceedings of the BPS, 19-21 December 1988

Table 1 125I-Fb binding to platelets during the menstrual cycle Cycle day 7 14 21 26-32 Bmax (x103)* 15.4 ± 1.9a 18.0 ± 3.2 15.7 ± 1.9 21.0 ± 1.9 16.0 ± 3.2b 17.2 ± 2.6 15.6 ± 3.9 16.0 ± 5.1 *molecules Fb bound per platelet a = normal cycle (n = 10), b = on contraceptive pill (n = 3)

Jones, S. et al. (1983). Clin. Pharmac. Ther., 34, 90. Marguerie, G. A. et al. (1980). J. biol. Chem., 255, 154.

a-adrenoceptor supersensitivity in positions during the first 5 min. These patients Parkinsonians with orthostatic hypotension did not suffer from either metabolic disturbance or electromyographic neuropathy. P. VALET, J. M. SENARD, G. DURRIEU, Parkinsonians with orthostatic hypotension M. BERLAN, M. A. TRAN, J. L. MONTASTRUC showed a 206% decrease in noradrenaline plasma & P. MONTASTRUC levels and a 150% increase in platelet a2- Laboratoire de Pharmacologie Medicale et Clinique, adrenoceptors ([3H]-yohimbine binding sites) INSERM U 317, Faculte de Medecine, Centre Hospi- with no change in Kd (Table 1). talier Universitaire Purpan, 37 allees Jules Guesde, The noradrenaline test consisted of infusion 31073 Toulouse Cedex France of cumulative doses while blood pressure was recorded using a Dynamap° system. The infusion Orthostatic hypotension is a current complica- was stopped for a 25 mmHg increase in systolic tion of Parkinson's disease. In order to investi- blood pressure: A25. In Parkinsonians with gate the adrenergic status of Parkinsonian orthostatic hypotension, A25 was obtained for patients with orthostatic hypotension, platelet a significantly (P < 0.01) lower dose (0.195 + ct2-adrenoceptor number, plasma catechol- 0.030 ,ug kg-') when compared with Parkin- amine levels and pressor responses to nor- sonians without orthostatic hypotension (0.863 adrenaline infusions were studied. ±0.110Lg kg-t). Seven Parkinsonians suffering from ortho- This study demonstrates that in patients with static hypotension (three women and four men, Parkinson's disease, orthostatic hypotension is mean age: 70 years) and seven other Parkin- associated with a high number of platelet a2- sonians without orthostatic hypotension (age, adrenoceptors and an increased sensitivity to sex and treatment matched) were included in noradrenaline, suggesting the existence of an the study. Patients with orthostatic hypotension a-adrenoceptor supersensitivity in such patients. were characterized by a dramatic and signifi- It indicates that the platelet a2-adrenoceptor is cant (P < 0.05) fall in systolic and diastolic a suitable index to investigate the adrenergic blood pressures from supine (144 ± 9/76 ± 6 status in patients with Parkinson's disease. mmHg) to standing (93 ± 10/58 ± 6 mmHg)

Table 1 Plasma catecholamines and platelet a2-adrenoceptors NA A B,, Kd (pg ml-) (pg ml-,) (fmolmg-' protein) (nM) Parkinsonians without 190 ± 25 55 ± 13 125 ± 19 2.7 ± 0.3 orthostatic hypotension Parkinsonians with 62 ± 11* 42 ± 10 313 ± 52* 2.6 ± 0.5 orthostatic hypotension Means are values ± s.e. mean, *P < 0.05 when compared with Parkinsonians without orthostatic hypotension. NA: noradrenaline, A: adrenaline, Bmax: total [3H]-yohimbine binding sites, Kd: dissociation constant. Proceedings of the BPS, 19-21 December 1988 683P

A preliminary pharmacokinetic and extraction into sulphuric acid (0.05 M). The limit pharmacodynamic evaluation of a novel of detection of the assay, defined as three times al-adrenoceptor antagonist UK 52046 baseline noise, was 20 pg ml-' the assay being linear in the range 20-500 pg ml-'. Inter- and S. H. K. MILLER, P. A. MEREDITH, intra-assay variability assessed across the con- R. F. SCHAFERS & H. L. ELLIOTT centration range was less than 10%. University Department of Materia Medica, Stobhill Following i.v. administration to six volun- General Hospital, Glasgow G21 3UW teers at a dose of 0.5 jig kg-' (mean dose 37 + 4 ,ug) UK 52046 levels were determined in whole In animals ax-adrenoceptor antagonists have blood up to 12 h post-dosing. Using model- been shown to be effective in restoring sinus dependent least squares fitting a two-compart- rhythm after experimentally-induced ischaemic ment model was most appropriately fitted to the and reperfusion arrhythmias. Preliminary data and from this the mean clearance was 63.1 evaluation in normal volunteers (Schafers et al., + 111 h-1 and the terminal elimination half-life 1989) has indicated that UK 52046 (4-amino- was 5.9 ± 1.4 h. The relationship between drug 6,7-dimethoxy-2-(1,2,3,4-tetrahydro-6,7-di- levels and a1-adrenoceptor antagonism was methoxy isoquinol-2-yl) quinoline methane- evaluated by direct correlation. a1-adreno- sulphate) has a1-adrenoceptor antagonist ceptor antagonism was assessed by measuring activity in the absence of profound tachycardia pressor response to i.v. infusions of phenyle- and postural hypotension. In order to evaluate phrine at 1, 6, 8 and 12 h post dose. Phenyl- concentration-effect relationships with UK ephrine dose ratios (PHE-DR) were calculated 52046 a new h.p.l.c. assay was developed, vali- from the dose of phenylephrine required to raise dated and applied in a study designed to investi- blood pressure by 20 or 15 mmHg with drug and gate the duration of action of a single i.v. dose placebo. For the group data the PHE-DR for of the drug. both systolic and diastolic blood pressure were The h.p.l.c. assay utilised fluorescence detec- correlated with log drug concentrations (r = tion (excitation 255 nm, emission 360 nm) with 0.78 and r = 0.60: P < 0.01 respectively). separation of drugs and internal standard on a These results indicate, in a study where no rigid macroporous co-polymer column (Hamilton profound haemodynamic effects were observed 5 ,. PRP-1). Using this column it was possible (as measured by blood pressure and heart rate to use a basic (pH = 12) mobile phase which responses) that al-adrenoceptor antagonism enhanced both resolution and sensitivity. Ex- associated with intravenous UK 52046 is related traction of drug from 2 ml of whole blood was to circulating drug levels. achieved by addition of alkaline ether and back

Schafers, R F. et al. (1989). Br. J. clin. Pharmac., 27, 102P.

Effects of atenolol, nifedipine and their et al., 1988). The aim of this investigation was combination on the cardiovascular system to study the effect of a combination of atenolol and finger tremor in normal man and nifedipine on the cardiovascular system and finger tremor (FT). E. M. WHITEHEAD, J. G. RIDDELL & Eight male volunteers, age 23.1 ± 1 years R. G. SHANKS (mean ± s.e. mean) and weight 72.6 ± 5.6 kg, Department of Therapeutics and Pharmacology, The received, double-blind, in random order, at Queen's University of Belfast, Belfast, Northern weekly intervals, single oral doses of atenolol Ireland 50 mg, sustained release nifedipine 20 mg, their combination, or a matching placebo. After 60 Atenolol and pifedipine are both widely used min supine rest in a room at constant tempera- in the treatment of hypertension. Nifedipine ture (24-25o C), resting heart rate (HR) was increases forearm blood flow (FBF) in both measured from an ECG, FBF by venous occlu- normal volunteers and hypertensive patients sion plethysmography, blood pressure (BP) with (Lederballe Pedersen et al., 1980) but atenolol a random-zero sphygmomanometer, and finger reduces FBF in normal volunteers (McCaffrey tremor (FT) with a piezo-electric accelerometer. 684P Proceedings of the BPS, 19-21 December 1988 Observations were repeated at 30 min intervals combined treatment 122.0 ± 2.9 beats min-'). for 180 min after drug administration. An exer- Atenolol reduced SBP at 120 min and com- cise step test was performed at the conclusion bined treatment at 90 and 180 min. SBP was of each study. Significant differences (P < unchanged after nifedipine. No changes were 0.025), detected using analysis of variance, para- seen in DBP. Small reductions, which were not metric or non-parametric as appropriate, are statistically significant, in FBF were observed reported as means ± s.e. mean. after atenolol. Nifedipine increased FT at 90 min. Compared with placebo, atenolol significantly Atenolol and nifedipine in combination pro- reduced HR at 30, 60, 90, 150 and 180 min and duced similar changes in HR and BP to atenolol the atenolol nifedipine combination at 90 and alone. FBF was unchanged by sustained release 180 min. Nifedipine produced small increases in nifedipine, singly or in combination with HR, significant at 120 min. Atenolol, singly and atenolol. The increase in FT with nifedipine in combination with nifedipine reduced exercise was not seen when combined with atenolol. HR (placebo 157.8 ± 4.0, atenolol 121.1 ± 4.8,

Table 1 Observations at 90 min (mean ± s.e. mean) FBF HR SBP DBP (ml 100 ml-, FT (beats min-) (mmHg) (mmHg) min-') (% change) Placebo 57.5 ± 1.6 105.8 ± 3.0 63.8 ± 1.6 3.7 ± 0.2 -4.1 ± 5.7 Atenolol 51.5 ± 2.3* 102.8 ± 2.9 66.1 ± 1.5 2.7 ± 0.2 -4.5 ± 4.5 Nifedipine 60.6 ± 1.6t 108.6 ± 3.Ot 64.6 ± 2.6 3.4 ± 0.4 41.2 + 26.2* Atenolol + 52.8 ± 2.0*1: 102.0 ± 1.4*t 63.0 ± 2.4 3.2 ± 0.3 -13.6 ± 9.6t nifedipine *P < 0.025 compared with placebo, 1nifedipine, tatenolol.

Lederballe Pedersen, 0. et al. 1980). J. cardiovasc. McCaffrey, P. M. et al. (1988). Eur. J. clin. Pharmac. Pharmac., 2, 357. (in press).

A dose-ranging study to evaluate the 13l-adrenoceptor blockade to A50). Three cardioselectivity of atenolol in normal hours after drug ingestion, dose-response curves subjects (DRC) were constructed using cumulative doses of inhaled salbutmol (200-6200 ,ug), HR, Tr B. J. LIPWORTH*, L. C. McFARLANE, and sGaw were measured at each dose incre- W. COUTIE & D. G. McDEVITT ment, made every 20 min. In addition, blood Department of Clinical Pharmacology, Ninewells was taken for assay of plasma potassium, glucose Hospital and Medical School, Dundee DD1 9SY and atenolol before and at the end of the study. Individual regression lines for each subject were The purpose of the present study was to quantify used to calculate the log dose of salbutamol the 32-adrenoceptor blockade of atenolol and required to increase HR by 15 beats min-', Tr propranolol on chronotropic (HR), finger by 50% and sGaw by 50%. These values were tremor (Tr), airway (sGaw) and metabolic (K then compared with placebo response to calcu- and Glu) responses to salbutamol, and to assess late dose ratios (expressed as geometric mean). the effect of dose on the cardioselectivity of Multiple ANOVA and paired t-tests were used atenolol. to compare different treatments. Five non-atopic, non-smoking, healthy volun- There were dose dependent increases in teers were given oral doses of atenolol 50 mg, plasma atenolol levels (ng ml-'): 281.4 ± 21.6 100 mg, 200 mg (A50, A100, A200), pro- (A50), 504.6 ± 66.5 (A100), 697 ± 99.1 (A200): pranolol 40 mg (P40) or identical placebo (PI) A100 vs A50 (P < 0.05), A200 vs A100 (P < in single-blind cross-over design, on five separate 0.05). There were no significant differences days, at 1 week intervals (P40 has equipotent (ANOVA) in baseline values between treat- Proceedings of the BPS, 19-21 December 1988 685P ments and placebo, for all variables. Mean -0.20 ± 0.09 (A200), P < 0.01. However, AK baseline HR showed a trend towards lower with A200 was significantly different from the values with ,3-adrenoceptor blockade, although response with P40: +0.12 ± 0.05 (P < 0.05). there was a wide overlap between the 95% There were partial reductions in the hyper- confidence intervals: P1 64 beats min-1 (53- glycaemic response with P-adrenoceptor 76), A50 54 (43-65), A100 56 (45-67), A200 57 blockade, although this was only significant (46-68), P40 55 (44-67). (compared with P1) for P40: AGlu 1.92 ± 0.50 There was gradual displacement of the DRC mmol 1-1 (Pt) vs 0.76 + 0.20 (P40), P < 0.05. to the right with increasing doses of atenolol, In conclusion, these results show that 1l- the greatest with propranolol. Dose ratios adrenoceptor selectivity is a dose dependent showed progressive attenuation of 132-adreno- phenomenon, although the P2-adrenoceptor ceptor responses for A50, A100, A200 and P40, blockade of A200 was much less than with P40. as follows: HR: 1.98, 2.75, 4.29; Tr: 1.60, 3.78, The antagonist effects on 32-adrenoceptors 6.34, 80.50; sGaw 1.08, 4.35, 12.30, 66.0. There occurred to a similar degree for HR, Tr, sGaw were significant differences between treatments and K responses. We found that HR and K for HR (P < 0.001), Tr (P < 0.01) and sGaw were the least variable indices of P2-adreno- (P < 0.05). ceptor antagonism, and suggest that these para- Increasing doses of atenolol were associated meters may be the most reproducible methods with progressive attenuation of AK compared of evaluating the cardioselectivity of new 12- with placebo: -0.72 ± 0.08 mmol 1-1 (P1), vs adrenoceptor blocking drugs.

Pharmacodynamic study of nicardipine group study of placebo or nicardipine/atenolol and atenolol using an echo doppler cardiac treatment. Four sets of control haemodynamic output method measurements at rest were obtained following which patients received either placebo or B. SILKE, J. M. EVANS, S. P. VERMA, atenolol 4 mg i.v. over 2 min. Haemodynamic A. V. ZEZULKA & S. H. TAYLOR measurements were repeated at 5 and 10 min. Departments of Cardiovascular Studies, Leeds Uni- Finally patients received either placebo or versity, and Leeds Infirmary, Medical Physics, Bristol nicardipine 5 mg i.v. with measurements re- Royal Infirmary, Bristol peated again at 5 and 10 min. When nicardipine was added to atenolol, A new non-imaging echo-doppler ultrasound compared with a matched placebo group, the device (Quantascope-Vital Science) circum- depressed heart rate and cardiac output follow- vents many of the limitations of doppler ultra- ing atenolol monotherapy was reversed. Cardiac sound estimations of cardiac output; its use of performance was improved compared with con- the principle of attenuated compensated volume trol observations in that the 35% reduction in flow (ACVF), together with an estimate of its systemic vascular resistance markedly increased accuracy and reproducibility has been previously cardiac index (P < 0.01) together with augmen- described (Silke et al., 1988). tation of time averaged mean velocity (P < To assess the utility of this technique during 0.01) and cardiac strokes length (P < 0.05). pharmacodynamic intervention in man, a study These data suggest that this method is useful of nicardipine and atenolol interaction was in assessing the acute pharmacodynamic actions undertaken. Twenty consecutive patients with of cardioactive drugs in man. stable angina were randomised to a parallel 686P Proceedings of the BPS, 19-21 December 1988

Table 1 Mean ± s.e. mean data Control Atenolol Nicardipine Cardiac output Placebo 6.7 ± 0.4 6.6 ± 0.4* 6.7 ± 0.3** (1 min-') Active 7.5 ± 0.5 6.8 ± 0.4 8.9 ± 0.5 Stroke length Placebo 14.1 ± 0.8 13.6 ± 1.0* 13.7 ± 1.0* (cm) Active 12.3 ± 0.8 11.8 ± 0.8 13.2 ± 1.0 Time averaged Placebo 15.2 ± 0.9 14.5 ± 0.6* 14.5 ± 0.7** mean velocity Active 13.2 ± 0.7 11.5 ± 0.7 14.9 ± 0.9 (cm s-1) Statistics ANOVA-changes from control between groups. *P < 0.05, **P < 0.01

Silke, B. et al. (1988). Br. J. clin. Pharmac., 25, 639P.

otl-adrenoceptor antagonism and presence and absence of drug was determined haemodynamic effects of UK-52,046 for each subject and geometric means with 95% compared with prazosin confidence intervals (CI) calculated. The systolic PD20 ratio for UK-52,046 (3.4, 95% CI, 2.2-5.3) B. TOMLINSON*, J-C. RENONDIN, was the same as for prazosin (3.5, 95% CI, 2.4- B. R. GRAHAM & B. N. C. PRICHARD 5.0) but the diastolic pressor response appeared Department of Clinical Pharmacology, University different as a rise of 15 mmHg in diastolic BP College and Middlesex School of Medicine, London was generally not achieved after prazosin but WC1E 6JJ was after UK-52,046 with the maximum dose of PHE which was limited by the systolic BP rise. a-adrenoceptor antagonists have been shown Estimated diastolic PD15 ratio after prazosin to protect against arrhythmias provoked by was 10.9 (95% CI 5.4-21.8) and after UK-52,046 ischaemia or reperfusion (Sheridan et al., 1980) 5.3 (95% CI 2.9-9.8) bsut the difference was not but the drugs currently available might be ex- significant. Acute reduiction in supine systolic pected to sometimes excessively lower the BP after total dose was similar for UK-52,046 blood pressure. UK-52,046 [4-amino-6,7-di- (8.5 ± 4.2 mmHg) and prazosin (10.9 ± 6.5 methoxy-2-(1,2,3,4-tetrahydro-6,7-dimethoxy- mmHg) but supine diastolic BP wa, reduced isoquinol-2-yl) quinoline methanesulphonate] is more (P < 0.05) by prazosin (2.8 + 2l8 mmHg) a selective a1-adrenoceptor antagonist which than UK-52,046 (rise of 1.7 ± 3.6 mmHg). has antidysrhythmic activity in animals with Marked orthostatic effects were seen after the doses that have minimal haemodynamic effects first dose of prazosin and one subject could not (Aubry et al., 1988). We have compared the be tilted beyond 600. Fall in systolic BP on 80° ol-adrenoceptor antagonism and haemo- tilting was greater (P < 0.05) with prazosin dynamic effects of UK-52,046 with a standard (17.3 ± 8.3 mmHg) than UK-52,046 (0.6 ± 10.2 a1-adrenoceptor antagonist, prazosin. mmHg immediately after total dose but differ- Six healthy male subjects (aged 21-37 years) ences were not significant at subsequent times. received cumulative i.v. doses at 30 min inter- Supine HR increased to a peak 3 h after both vals of UK-52,046 0.2, 0.4 and 0.8 ,ug kg- drugs (UK-52,046, 73.4 ± 8.0, prazosin 68.5 ± or prazosin 4, 8 and 16 ,ug kg-1 randomised 12.5 beats min-'). HR rise with tilting reached double-blind. Graded passive head-up tilting peaks after the second dose of prazosin (38.7 ± was performed prior to dosing, after each dose 7.1) or the third dose of UK-52,046 (34.6 ± and at 3, 4, 5 and 24 h post first dose. Cycle 10.3) and remained elevated over 5 h, similarly exercise was performed pre-dose and at 2.5, with the two drugs. The rise in HR and systolic 3.5, 4.5 and 5.5 h post dose. Phenylephrine BP with exercise was not affected by either drug. (PHE) pressor responses were calculated pre- Greater inhibition of diastolic than systolic dose and after the final doses and pressor doses PHE pressor response has been described pre- for a rise of 20 mmHg (PD20) in systolic BP viously with prazosin (Singleton et al., 1982). calculated. The ratio of PD20 values in the The diastolic response may be more dependent Proceedings of the BPS, 19-21 December 1988 687P upon effects on peripheral ox1-adrenoceptors having similar effects on PHE systolic pressor whereas the systolic response may have a greater response suggesting less inhibition of peripheral cardiac component due to cardiac ot1-adreno- a1-adrenoceptors at equal levels of cardiac oxl- ceptors which have inotropic effects (Bruckner adrenoceptor antagonism. et al., 1985). UK-52,046 appears to show less inhibition of the PHE diastolic pressor response This work was supported by Pfizer Central Research, and less orthostatic effects than prazosin at doses U.K.

Aubry, M. L. et al. (1988). Br. J. Pharmac. (in press). Sheridan, D. J. et al. (1980). J. clin. Invest., 65, 161. Bruckner, R. et al. (1985). J. Mol. Cell. Cardiol., 17, Singleton, W. et al. (1982). J. cardiovasc. Pharmac., 639. 4, S145.

Differential actions of clonidine and structed to tyramine, and after a further 15 min rihmenidine on peripheral ot2-adrenoceptors to a-methylnoradrenaline (MN). Measure- in man ments included BP, HR, skin blood flow (by Laser Doppler), sedation, and plama levels of M. J. BROWN, D. J. REYNOLDS & M. J. ASHBY noradrenaline, growth hormone and insulin. Clinical Pharmacology Unit, Cambridge University, Both CLON and RIL caused their charac- Level 2 F&G Block, Addenbrooke's Hospital, teristic a2-adrenoceptor mediated falls in BP, Cambridge CB2 2QQ plasma noradrenaline and insulin, with increases in sedation and plasma growth hormone (Table Clonidine (CLON) and rilmenidine (RIL) are 1). The changes following CLON were slightly partial a2-adrenoceptor agonists. RIL has been greater, but significantly different from RIL suggested to have less sedative action, and the (multiple regression analysis) only for systolic objective of the present study was to determine BP, sedation and plasma noradrenaline. Neither whether a greater part of its hypotensive action drug shifted the pressor dose-response curve to is mediated in the periphery (through stimulation tyramine, but both caused a left-shift in the of presynaptic a2-adrenoceptors). In addition pressor and skin flow responses to MN. The to standard haemodynamic and neuroendocrine principal difference between RIL and CLON indices of a2-adrenoceptor function, we in- was a significant enhancement (P = 0.01) by vestigated whether changes in noradrenaline RIL of the release of noradrenaline during in- release during tyramine infusion may provide a fusion of tyramine (Figure 1). 'dynamic' index of presynaptic a2-adrenoceptor The presence of a partial a2-adrenoceptor activity. agonist at the presynaptic receptor during in- Seventy-five minutes after an oral dose of creasing noradrenaline release may further timolol 10 mg, six healthy male volunteers re- facilitate release by blocking the negative feed- ceived (in randomised Latin-square design) on back loop, and this finding may therefore sup- three occasions a 30 min i.v. infusion of either port the hypothesis that RIL has a therapeutic CLON 0.15 mg, RIL 1 mg or vehicle. Two action at the peripheral presynaptic receptor. hours later, dose-response curves were con-

Table 1 Results of the study (mean ± s.e. mean) BP Noradrenaline Insulin Sedation (visual GH (mmHg) (pg ml-') (mU 1-1) analogue: cm) (mU l-]) Pre 120 min Pre 120 min Pre 60 min Pre 60 min Pre 60 min

Vehicle 114/64+5/3 116/68±3/4 133±38 206±43 15±5 8±2 1.7+7 3.3± 1.15 6.5±4 5.7±3.3 110/59 102/51 172 107 15 6 2.2 4.8 7.3 12.9 RilmenidineRimein +4/2 ± 4/2 ± 25 ± 42 ± 4 ± 1 + 0.7 ± 1.2 ± 4.1 ± 5.7 113/61 98/48 114 61 15 6 1.5 6.3 2.6 9.5 ClonidineCloni±ne +3/2 ± 5/1 ± 33 ± 11 + 5 + 1 ± 0.8 ± 1.4 ± 0.6 ± 3.8 688P Proceedings of the BPS, 19-21 December 1988

400 -

300 - 200 / ' I z 100 E '..&d 0 ~ CUuo1 -100- 10 100 Infusion rate (R,g kg-' min-1) Figure 1 Tyramine dose-response curve (mean + s.e. mean) (a rilmenidine, 0 clonidine, A vehicle).

Non-invasive haemodynamic parameters to the nisoldipine-induced reduction of after- in clinical pharmacology. What can the load 2 h after drug administration the haemo- Heather-Index be used for? dynamic parameters showed the typical signs of improved cardiac performance. In mechano- M. LINDE & W. KIRCH cardiography 10 mg nisoldipine caused a decrease I. Medizinische Klinik, Christian-Albrechts-Univer- of PEPC from 139.0 ± 6.47 ms (mean ± s.e. sitat, Kiel, FRG mean) to 119.3 ± 4.56 ms (P < 0.01); the PEP/ LVET-ratio was reduced from 0.362 ± 0.02 to In clinical pharmacology non-invasive tech- 0.308 ± 0.012 (P < 0.01). The impedance- niques are indispensable for longer-lasting cardiographic parameters, on the other hand, observations concerning the haemodynamic increased after administration of the calcium- effects of drugs. While the usefulness of these channel blocker. While the changes in stroke techniques for estimating cardiac performance volume were not significant, the Heather-Index in general is beyond question, it has to be rose significantly from 12.83 ± 1.12 Ql S-2 doubted if the non-invasive parameters provide (mean ± s.e. mean) to 17.79 ± 1.83 Q s-2 (P any specific information about preload, after- < 0.01) 2 h after ingestion of 10 mg nisoldipine. load or myocardial contractility. As to mechano- These effects, which vanished within 6 h after cardiography, Joubert & Belz (1987) pointed administration of the drug, could not be de- out that changes in the preejection-period tected at all after placebo. With the Heather- (PEPC) cannot be specific for inotropism. Index being changed by a drug with obviously By means of mechano- and impedance cardio- no positive-inotropic properties, the statement graphy the daily course of haemodynamic para- of Hubbard et al. (1986), who declares this index meters following the administration of a calcium- to be a parameter of myocardial contractility, channel blocker was measured in 18 patients has to be reviewed critically. The results of the with congestive heart failure (NYHA II; 63 + present study seem to reveal that the Heather- 2.8 years; body weight 75 ± 4.4 kg; mean ± s.e. Index is no parameter of contractility but a use- mean). The investigation was performed as a ful measurement of cardiac performance in randomized placebo-controlled double-blind general. Thus the statement of Joubert & Belz study. Before as well as 2, 6, 12 and 24 h after (1987), that the STIs should always be inter- administration of single oral doses of placebo, preted in the light of the various determinants 5 or 10 mg nisoldipine systolic time intervals of ventricular function, is-to our minds-valid (STI), stroke volume (AV) and the Heather- for impedance cardiography as well. Index (HI) were registered non-invasively. Due

Hubbard, W. N. et al. (1986). Int. J. Cardiol., 12, 71. Joubert, P. H. & Belz, G. G. (1987). Eur. J. clin. Pharmac., 33, 335. Proceedings of the BPS, 19-21 December 1988 689P

Comparative study with CGRP in Raynaud's min-' and 2, 4, 6, 8 ng kg-1 min-1 respec- phenomenon and normal volunteers tively). Each drug was given for 20 min. There was a 20 min infusion of vehicle after ATP and S. A. SHAWKET, C. DICKERSON, PGI2 and 60 min after CGRP. ATP and PGI2 B. HAZELMAN & M. J. BROWN were given in a double-blind crossover fashion. Clinical Pharmacology Unit, Rheumatology Research Parameters measured were: SBP, DBP, heart Unit, Addenbrooke's Hospital, Cambridge CB2 2QQ rate (HR), and skin blood flow (SBF) in the hand and face using Laser Doppler Flowmeter. The potent vasodilating activity of calcitonin These results confirm our previous observa- gene related peptide (CGRP) and its presence tion in normal subjects. Human oaCGRP caused in abundance in perivascular nerves suggests an flushing and increased SBF in the face but not important role for CGRP in controlling peri- in the hand of healthy subjects (Table 1A), pheral vascular tone. Our previous pilot study whereas patients with Rp had marked flushing in patients with Raynaud's phenomenon (Rp) both in their face and hands accompanied by suggested increased sensitivity of skin blood significant rise in SBF (Table 1). Both patients flow (SBF) in the hands to CGRP. This study and healthy subjects had similar flushing in their was designed to determine whether patients with hands in response to PGI2. ATP did not cause Rp are more sensitive to CGRP than normal any significant changes in SBF of the face or healthy volunteers, and to compare the effects hands in patients but in normal subjects it in- of ATP and PGI2 in patients with Rp with that duced significant increase in SBF in the face. In in normal volunteers. conclusion patients with Rp seem to be more Seven patients aged 24-50 years with Rp sensitive to CGRP than normal volunteers. were compared with age-sex matched normal Therefore these results may suggest a relative subjects. Subjects were infused intravenously deficiency of endogenous CGRP release in this with four doses of CGRP, ATP and PGI2 (2, condition. 4, 8, 16 ng kg-1 min-' 25, 50, 75, 125 ug g-1

Table 1 Results of parameters measured: mean ± s.d. ('pre' is baseline, 'max' is measurement at the highest dose) HR SBP DBP (beats SBF (face) SBF (hand) (mmHg) (mmHg) min 1) units % change units % change A (control) CGRP pre 118 ± 12 68 ± 7 69 ± 13 31 ± 18 100% 8 ± 4 37% max 111 + 11 63 ± 7 88 ± 11 62 ± 18 11 ± 5 P = 0.77 PGI2 pre 114 ± 11 64 9 69 ± 13 31 ± 15 67% 7 ± 5 242% max 110 ± 9 61 6 84 ± 13 52 ± 20 24 ± 16 P < 0.05 ATP pre 117 ± 11 66 5 67 ± 9 32 ± 14 50% 7 ± 4 14% max 117± 11 68 6 101 ± 14 48± 16 8±4 B (patients) CGRP pre 118 ± 13 68 ± 10 62 ± 7 39 ± 30 63% 15 ± 10 153% max 110 ± 10 59 ± 12 81 ± 6 64 ± 27 38 ± 22 P < 0.05 PGI2 pre 116 ± 10 67 ± 8 65 ± 5 40 ± 30 35% 17 ± 11 141% max 114 ± 11 66 ± 7 80 ± 11 54 ± 32 41 ± 19 P < 0.05 ATP pre 120 ± 14 70 ± 10 61 ± 5 40 ± 24 -7% 17 ± 10 0 max 118 ± 8 68 ± 12 81 ± 11 39 ± 22 17 ± 12 690P Proceedings of the BPS, 19-21 December 1988 Endothelin causes prolonged vasocon- thesia with a twin port teflon cannula, allowing striction in the human forearm infusion and concurrent direct measurement of arterial pressure. First saline, and subsequently S. THOM, A. D. HUGHES, N. WOODALL & endothelin at incremental infusion rates (10 P. S. SEVER ,umol, 100 ,umol, 1 nmol, 10 nmol min-') were Department of Clinical Pharmacology, St Mary's infused. FBF was measured during the last 2 Hospital Medical School, London W2 lNY min of infusion at each step, and subsequently at 20, 40 and 60 min after washout with con- Evidence has been growing for the existence of tinued saline infusion. Flow measurements in an 'endothelium-derived vasoconstrictor factor' the opposite arm served as control throughout. (Katusic et al., 1987), and recently endothelin The net % change in FBF was calculated by has been defined in porcine aortic endothelial subtracting the percentage change in the con- cells (Yanagisawa et al., 1988). Data from this trol arm FBF from the percentage change in the laboratory have described the potent and pro- infused arm FBF. There was no significant longed contractile effect of endothelin on human change from baseline values in either FBF in isolated resistance arteries (Hughes et al., 1989). the control arm, or in blood pressure. This study investigated the effect of endothelin These results indicate that endothelin is a on blood flow in the forearm. potent constrictor of human circulation in vivo. Five healthy male volunteers (age 23-35 years) The prolonged effect and the appearance of participated in the study. Ethical approval was greater reduction in blood flow after cessation obtained from the St Mary's Ethics Committee. of endothelin infusion may relate either to access Forearm blood flow (FBF) was measured to the smooth muscle of the resistance vessels, in both arms in the recumbent position using or activation of the contractile process. Alter- mercury-in-silastic strain gauge plethysmo- natively endothelin may activate a concurrent graphy. The brachial artery of the study arm dilator mechanism with a short half-life. was cannulated under lignocaine local anaes-

Table 1 Endothelin (nmol min-]) Washout (min) 0 0.01 0.1 1 10 20 40 60 FBF 3.0 2.9 2.6* 2.4* 2.0* 1.9* 2.0* 2.2* (ml 100 ml-' min-') ± 0.3 ± 0.5 ± 0.4 ± 03 ± 0.3 ± 0.4 ± 0.4 ± 0.4 Net % change 0 -10 -12* -21* -33* -42* -38* -33* inFBF ±4 ±7 ±5 ±10 ±15 ±14 ±17 The values represent mean values ± s.e. mean. Results were analysed by Wilcoxon signed ranks test, *P < 0.05.

Hughes, A. D. et al. (1989). Br. J. Pharmac. (in Yanagisawa, M. et al. (1987). Nature, 332, 411. press). Katusic, Z. S. et al. (1987). Am. J. Physiol., 252, H671.

Effect of tissue-type plasminogen activator It is claimed that recombinant human tissue- in haemostasis. Coagulation and type plasminogen activator (rt-PA) will lyse thrombosis: an in vitro study from native thrombus without inducing systemic activation blood of the fibrinolytic system. Although the high frequency of reperfusion was appreciated in I. B. KOVACS*, C. D. RIDLER, S. M. L. ABRAMS clinical studies, a substantial decline in plasma & P. GOROG fibrinogen concentration and development of Thrombosis Unit, Department of Haematology, coronary reocculusion in some patients were also St Bartholomew's Hospital, London EClA 7BE demonstrated. To understand the mechanism Proceedings of the BPS, 19-21 December 1988 691P by which early reocclusion occurs, following Twenty-four healthy subjects were studied. initial reperfusion, the haemostatometer was The thrombolytic activity of blood was increased used in the present study. This technique allows both by 50 ng ml-' rt-PA and 200 ng ml-' rt- the simultaneous measurement of primary PA. In both concentrations, rt-PA enhanced haemostasis, coagulation and spontaneous coagulation. The effect on haemostasis fell into thrombolysis from nonanticoagulated (native) two groups. In 11 subjects, rt-PA caused dose- blood samples (Gorog & Kovacs, 1986; Gorog, dependent inhibition of the parameters of 1986; Kovacs et al., 1989). The technique in- primary haemostasis (subgroup I) while in 11 duces 'bleeding' by punching holes in a poly- patients, haemostasis parameters were signifi- ethylene tubing whilst the blood is perfused cantly enhanced (subgroup II). In the latter through it and monitors the haemostatic plug subjects, 300 mg aspirin taken 2 h before the formation. The time-lapse for the expulsion test prevented the haemostasis-enhancing effect of the haemostatic plugs to occur measures of rt-PA. Enhanced coagulation and individual thrombolysis. The effects of 50 and 200 ng rt- variations in platelet behaviour in response to PA ml-' blood on haemostasis, clotting and rt-PA could explain the unpredictable risk of thrombolysis were compared with identical rethrombosis and necessitate monitoring during blood samples without rt-PA (Table 1). infusion.

Table 1 Effect of rt-PA on haemostasis, coagulation and thrombolysis in non- anticoagulated human blood in vitro (mean ± s.e. mean) rt-PA Number of Haemostasis Coagulation Thrombolysis (ng ml-') subjects (s) (min) (min) None 24 179 ± 21 13.3 ± 0.4 41.2 ± 3.9 50 24 159 ± 16 11.2 ± 0.3* 26.4 ± 1.7* 200 24 123 ± 13* 10.6 ± 0.3* 17.9 ± 0.8* Subgroup I None 11 124 ± 16 9.9 ± 0.8 43.5 ± 5.2 50 167 ± 14* 7.4 ± 0.5* 28.4 ± 3.0* 200 172 ± 15* 7.9 ± 0.4* 17.7 ± 0.3* Subgroup II None 11 206 ± 32 13.3 ± 0.5 43.6 ± 4.9 50 170 ± 31 7.5 ± 0.3* 25.6 ± 2.0* 200 70 ± 10* 6.9 ± 0.5* 18.3 ± 1.8* 200 + aspirin 156 ± 34 7.9 ± 0.9* 18.0 ± 0.7* *Differences from the respective controls (without t-PA): *P < 0.001

Gorog, P. (1986). Angiology, 37, 99. Kovacs, I. B. et al. (1989). Am. J. clin. Path., 91, Gorog, P. & Kovacs, I. B. (1986). Haemostasis, 16, 271-279. 337.

Comparison of the effects of fengabine and derivative with a unique preclinical pharmaco- amitriptyline on psychomotor and logical profile: while it does not block the uptake autonomic functions in healthy volunteers of noradrenaline and/or 5-hydroxytryptamine, or inhibit monoamine oxidase, it increases nor- N. THEOFILOPOULOS, C. M. GRAY, adrenaline turnover and reduces central 1- E. SZABADI & C. M. BRADSHAW adrenoceptor-mediated responses, after chronic Department of Psychiatry, University of Manchester, administration (Scatton et al., 1987). Further- Stopford Building, Oxford Road, Manchester M13 9PT more, the drug shows little interaction with muscarinic receptors (Lloyd et al., 1987). Initial Fengabine (SL79.229; 2-[butylimino)(2-chloro- clinical studies indicate that fengabine may be phenyl)methyl]-4chlorophenol) is a benzylidine an effective antidepressant (Musch & Garreau, 692P Proceedings of the BPS, 19-21 December 1988 1986). We have examined the psychomotor and sweating) were measured (Szabadi et al., 1980b) autonomic effects of this drug; amitriptyline 2.5 h after drug taking. Differences between served as positive control. pre-and post-drug values were used to assess Sixteen healthy male volunteers, aged 18-30 the effects of treatments; two-factor ANOVA years, participated in the experiment, eight in was used to identify differences between the Part A and eight in Part B. Each part consisted effects of active drugs and placebo (threshold of four weekly sessions. In each session one of of statistical significance: P < 0.05). the following drugs was taken: fengabine 300 Fengabine, similarly to placebo, did not affect mg, fengabine 600 mg, amitriptyline 50 mg, any of the test results. Amitriptyline caused placebo. Subjects were allocated to treatments decrements in subjectively rated alertness and and sessions according to a balanced double- contentedness, digit cancellation time, critical blind crossover design. In Part A, subjective flicker fusion frequency, salivation, diastolic mood state was rated using visual analogue blood pressure, heart rate and carbachol-evoked scales, psychomotor functions were assessed sweating, reflecting the sedative and antimus- by pencil-and-paper tests (digit cancellation, carinic properties of this drug. digit-symbol substitution, symbol copying) and It is concluded that fengabine, in clinically instrumental tests (wire-maze tracing, tapping relevant single doses, does not affect psycho- rate, critical flicker fusion frequency) and some motor and autonomic functions, and thus is baseline autonomic functions (salivation, pupil likely to be better tolerated by patients than diameter, heart rate, blood pressure) were amitriptyline. measured (Szabadi et al., 1980a; Theofilopoulos et al., 1984) 1, 3 and 5 h after drug taking. In This work was supported by L.E.R.S. and The Sir Part B, cholinoceptor-mediated tissue responses Jules Thorn Charitable Trust. (pilocarpine-evoked miosis, carbachol-evoked Lloyd, K. G. et al. (1987). J. Pharmac. exp. Ther., Szabadi, E. et al. (1980a). Psychopharmacology, 68, 241, 245. 125. Musch, B. & Garreau, M. (1986). In Biological Szabadi, E. et al. (1980b). Br. J. Psychiat., 137, 433. psychiatry ed. Shagass, C. et al. p. 920. New York: Theofilopoulos, N. et al. (1984). Br. J. clin. Pharmac., Elsevier. 18, 135. Scatton, B. et al. (1987). J. Pharmac. exp. Ther., 241, 251.

Comparison of tablet and controlled release related to plasma BZ concentrations measured capsule of diazepam: plasma levels and by direct radioreceptor assay (RRA) against effects on performance the Day 1 baseline samples (Aranko et al., 1985), and by gas liquid chromatography (g.l.c.). The M. E. MATTILA & M. J. MATTILA1 subjects received 15 mg DZ, 20 mg DZ-CR, or Departments of Pharmacology and Toxicology, and placebo on Days 1 and 8, and took these treat- 'Clinical Pharmacology, University of Helsinki, ments at home (10 mg diazepam daily) at bed- 00170 Helsinki, Finland time on Days 2 to 7. The treatments began at 2 week intervals. Performance tests (tracking, Fast absorption and rapid plasma peaks asso- choice reactions, digit substitution, flicker ciated with feeling 'high' characterize the acute fusion, Maddox wing) and assessment of mood oral intake of diazepam in regular tablet form on visual analogue scales were done before the (DZ). The controlled release capsule ('Schwim- drug intake and 1.5 and 3 h after it on both test mkapsel') (DZ-CR) provides a sustained release days. Venous blood was samples after each test- of drug and slowly rising plasma levels. That ing run. type of absorption might render the DZ-CR As seen in Table 1, plasma diazepam after formulation suitable for long-term treatment DZ rose more rapidly than after DZ-CR on with benzodiazepines (BZ). Day 1, diazepam and nordiazepam accumulated This randomized double-blind crossover study during maintenance about similarly from either was conducted in nine healthy students to docu- formulation, and slightly different absorptions ment the acute (Day 1) and subacute (Day 8) were again seen on Day 8. The g.l.c. assay and effects of DZ and DZ-CR on performance, as RRA assay gave comparable results, yet RRA Proceedings of the BPS, 19-21 December 1988 693P suggested the presence of extra BZ activity drug on both test days. DZ but not DZ-CR (oxazepam, temazepam ?) on Day 8. caused drowsiness and feeling of impaired per- On Day 1, DZ impaired digit substitution, formance in the laboratory whilst most subjects flicker fusion and tracking, prolonged reaction regarded both DZ and DZ-CR as sedative times, and caused exophoria (Maddox wing), at home. The results, however, suggest that mostly at 1.5 h. On day 8, DZ impaired digit decremental effects on performance are not a substitution and increased exophoria. DZ-CR major problem when treating neurotic states proved mostly inert in objective tests, yet in- with DZ-CR. creased exophoria was measured at 3 h post-

Table 1 Mean ± s.e. mean levels (ng ml-') of plasma diazepam and nordiazepam during the trial. Results by RRA expressed as diazepam also include its active metabolites Assay Day I Day 8 treatment 1.5 h 3 h BL 1.5 h 3 h RRA assay DZ tablet 370 ± 70 340 ± 50 450 ± 70 880 ± 140 860 ± 100 DZ-CR capsule 160 ± 70 310 ± 30 670 ± 90 970 ± 150 1180 ± 180 G.i.c. assay DZ tablet diazepam 417 ± 30 355 ± 40 295 ± 48 663 ± 61 514 ± 40 nordiazepam 57 ± 17 72 ± 24 257 ± 11 259 ± 12 252 ± 15 DZ-CR capsule diazepam 139 ± 50 263 ± 39 260 ± 29 403 ± 43 403 35 nordiazepam 0 0 203 ± 29 235 ± 41 231 + 4

Aranko. K. et al. (1985). Eur. J. clin. Pharmac., 28, 559.

Induction dose of thiopentone: the effect of pentone. These studies were all carried out on alcohol intake small groups of patients and because of the conflict of findings the present study was carried J. W. DUNDEE & K. R. MILLIGAN out to assess the effect of alcohol consumption Department of Anaesthetics, The Queen's University on the induction dose of thiopentone for a large of Belfast, Whitla Medical Building, 97 Lisbum Road, varied group of patients. Belfast BT9 7BL Five hundred and thirty-two healthy un- premedicated patients were studied. They were Thiopentone, a widely used barbiturate an- questioned about their alcohol consumption aesthetic agent is well known for the cardio- and on the basis of their replies were classified respiratory depression that it produces, especially as 'drinkers' or 'non-drinkers'. Non-drinkers in the elderly or poor risk patient. Animal studies were abstainers or those who drank only on suggest that regular alcohol consumption pro- rare occasions: drinkers were those who drank duces resistance to the anaesthetic but not the more than the equivalent of 2 pints of beer (40 g cardiorespiratory effects of anaesthetic drugs alcohol) per week or who had drunk more than (Wolfson & Freed, 1980). In man Tammisto 6 pints (120 g) in the previous month. & Tigerstedt (1977) were unable to show any Thiopentone 2.0 mg kg-1 was injected into a effect but Loft et al. (1982) considered that large forearm vein over 20 s. Thereafter 25 mg regular alcohol increased the dose of thiopen- increments were given away every 15 s until the tone required to induce anaesthesia. More eyelash reflex was abolished or contact lost with recently Swerdlow & Holly (1986) using spectral the patient. The total dose administered was edge analysis concluded that alcohol intake taken as the induction dose. does not influence the induction dose of thio- The results, statistically analysed using the 694P Proceedings of the BPS, 19-21 December 1988 independent samples t-test and multiple regres- are heavy users of alcohol (> 40 g daily) re- sion analysis, are summarised in Table 1. Those quired 33% and women 44% more thiopentone patients regularly consuming alcohol required for induction than non-drinkers. significantly larger doses of thiopentone to in- This study clearly demonstrates increased duce anaesthesia. After adjustment for differ- barbiturate requirements in subjects who con- ences in age and weight distribution men who sume more than 40 g of alcohol weekly.

Table 1 Mean (± s.e. mean) induction dose of thiopentone (mg kg-') by age decade Age (years) Non-drinkers (n) Drinkers (n) P 20- 4.5 ± 0.16 (64) 5.6 ± 0.27 (27) 0.001 30- 4.1 ± 0.16 (53) 5.6 ± 0.25 (29) 0.001 40- 4.3 ± 0.16 (46) 5.1 ± 0.30 (28) 0.01 50- 3.9 ± 0.14 (52) 4.7 ± 0.21 (26) 0.001 60- 3.3 ± 0.10 (80) 4.4 ± 0.23 (14) 0.001 70- 3.0 ± 0.09 (61) 3.6 ± 0.22 (14) 0.01 80- 2.9 ± 0.12 (34) 3.6 ± 0.32 (4) 0.06

Loft, S. et al. (1982). Acta Anaesthesiol. Scand., 26, Tammisto, T. & Tigerstedt, I. (1977). Acta Anaes- 22. thesiol. Scand., 21, 17. Swerdlow, B. N. & Holly, F. 0. (1986). Abstracts, Wolfson, B. & Freed, B. (1980). Anesth. Analg., 59, VII European Congress of Anaesthesiology, II, 826. 333.

A model for examining the onset of required to reduce the Vmax30p by 50% (PC50) Hl-receptor antagonism in man was determined by linear interpolation for each subject. P. ROLAN, J. ADAMS & J. POSNER Ten volunteers with values of PC50 between Wellcome Research Laboratories, Langley Court, 0.125 and 2 mg ml-' proceeded to the formal Beckenham, Kent BR3 3BS study in which each subject underwent bronchial challenge with histamine on five occasions at A rapid onset of action is a desired feature intervals of at least 7 days. Each challenge was of Hl-receptor antagonists, which may be used preceded by a single dose of Ac 8 mg at 1 (Acl) intermittently for relief of symptoms of hay- or 2 h (Ac2), Ter 60 mg at 1 (Terl) or 2 h (Ter2) fever. We have used antagonism of histamine- or placebo (Pla). Treatments were administered induced bronchoconstriction in sensitive volun- in a double-blind manner with dummy given at teers to compare the onset of antihistaminic the alternative time, according to a balanced, effect of a new H1-receptor antagonist acri- randomised, cross-over design. Bronchial chal- astine (Ac) with that of terfenadine (Ter). lenge was begun with a histamine concentration Airway sensitivity to histamine was assessed of 1/4 the subject's previous PC50 and the con- in 18 volunteers who were entirely healthy or centration doubled until either a 50% fall in had hayfever or mild asthma. Histamine chal- Vmax30p occurred or 8 x the PC50 had been lenge was performed with aerosol generated by reached. a Wright's nebuliser inhaled through a face- The response to bronchial challenge was mask using tidal breathing for 2 min. The de- assessed by measuring the area bounded by the crease in expiratory flow at 30% vital capacity curve of concentration and change in Vmax30p (Vmax3op) was measured using partial expir- from baseline between the 3rd and 6th concen- atory flow-volume loops performed 30, 90 and trations. A Vmax30p value higher than baseline 150 s after the end of each inhalation. Starting resulted in a 'positive' area, and a value lower at 0.03 mg ml-1, histamine concentrations were than baseline resulted in a 'negative' area. The doubled at 5 min intervals. The concentration results were subjected to analysis of variance. Proceedings of the BPS, 19-21 December 1988 695P Mean values of area ± s.d. (in arbitary units) 1 and 2 h and terfenadine at 2 h were indistin- were: Acl, -4,7.6 ± 45.6; Ac2, -53 ± 62; guishable but terfenadine at 1 h was inferior to Terl, -100 ± 64.3; Ter2, -63 ± 52.9 and Pla, the other three treatments indicating that the -153.8 ± 45.9. All active treatments signifi- onset of action of terfenadine is slower than cantly reduced the area under curve when com- that of acrivastine. Bronchial challenge with pared with placebo (P < 0.05) but the effect of histamine in responsive subjects provides a Ter 1 was significantly less than those of the model suitable for examining speed of onset of other three active treatments (P < 0.05). action of antihistamines in man. The antihistaminic action of acrivastine at

Modulation of rapid eye movement sleep 60 daytime sleeps recorded in healthy males aged and sleep continuity in man by drugs which between 18 and 29 years. Daytime sleeps and modify monoaminergic transmission 313 overnight sleeps were recorded after inges- tion of placebo, and the remaining overnight A. N. NICHOLSON, PETA A. PASCOE & sleeps were recorded after drugs which modulate A. J. BELYAVIN NA activity (24), inhibit 5-HT uptake (42) or Royal Air Force Institute of Aviation Medicine, Famn- have dopamimetic activity (41). TST and the borough, Hampshire duration of REM sleep were derived for placebo and for each group of drugs. Analysis of co- Modulation of rapid eye movement (REM) variance provided a quadratic relationship be- sleep and of sleep continuity is a well estab- tween TST and REM sleep with placebo, and lished effect of many drugs which modify central this gave the estimate of change in REM sleep synaptic transmission, but there is uncertainty brought about by change in sleep duration. concerning, the significance of the changes. TST was reduced compared with placebo Studies with benzodiazepines have shown that (465.5 min) by the 5-HT uptake inhibitors delay to REM sleep without any reduction over (444.1 min, P < 0.001) and by the dopamimetic the whole night is due to an increase in the agent, pemoline (391.3 min, P < 0.001), and incidence of sleeps without an early REM period was increased with the NA modulators (473.9 rather than to any change in the phase relation- min, P < 0.05). The duration of REM sleep was ship of REM sleep with sleep onset (Belyavin less with each group of drugs (NA modulators & Nicholson, 1987). Further, drugs which modify 68.2 min, 5-HT uptake inhibitors 66.3 min, monoaminergic transmission lead to marked pemoline 74.0 min, P < 0.001) than with placebo changes, and reduced REM sleep occurs with (110.6 min). The decrease in REM sleep with inhibitors of noradrenaline (NA) and 5-hydroxy- pemoline when corrected for the reduction in tryptamine (5-HT) reuptake and with the dopa- sleep duration was due solely to reduced TST mimetic agent, pemoline (Nicholson & Pascoe, while the marked decrease with the NA modu- 1986, 1988, 1989). It is difficult to be certain lators and 5-HT uptake inhibitors (P < 0.001) whether there is a direct effect on REM sleep occurred independently of any change in TST. as there are also changes in sleep continuity. These studies suggest that noradrenergic and It is in this context that we have carried out serotonergic systems, but not dopaminergic, the present studies on the relationship between are concerned directly with the appearance of total sleep time (TST) and REM sleep with REM sleep in man. Further, it is considered drugs which modify monoaminergic trans- that analysis of REM sleep together with sleep mission. continuity may be a means by which the central The data involved 420 overnight sleeps and activity of such drugs can be established in man.

Belyavin, A. J. & Nicholson, A. N. (1987). Neuro- Nicholson, A. N. & Pascoe, P. A. (1988). Neuro- pharmacology, 26, 485. pharmacology, 27, 597. Nicholson, A. N. & Pascoe, P. A. (1986). Neuro- Nicholson, A. N. & Pascoe, P. A. (1989). Br. J. clin. pharmacology, 25, 1079. Pharmac., 27, llOP. 696P Proceedings of the BPS, 19-21 December 1988 The effect of tiapamil on peripheral dose of tiapamil 300 mg, 600 mg or placebo haemodynamics, cardiac conduction, and according to a double-blind study design. plasma noradrenaline levels in healthy man Measurements were repeated at 45, 120, 240 and 360 min post dosing. A 10 ml venous sample M. B. FINCH & G. D. JOHNSTON for measurement of plasma tiapamil was also Department of Therapeutics and Pharmacology, The obtained at the above times and for noradrena- Queen's University of Belfast and Belfast City line levels, in the lying and standing positions Hospital, Belfast and after 3 min of exercise before and 2 h after dosing. Plasma tiapamil levels were determined Tiapamil is a new calcium channel antagonist by high performance liquid chromatography which is structurally related to verapamil. Pro- with ultraviolet detection (Heizmann et al., longation of the atrioventricular nodal refractory 1984) and plasma noradrenaline using an electro- period has been described previously using His chemical detector. For multiple data an analysis bundle electrograms and atrial pacing (Gmeiner of variance was used and for single paired data, et al., 1979a) and there is evidence that the a paired t-test. Results are expressed as the drug may be useful as an antiarrhythmic agent mean ± s.d. (Gmeiner et al., 1979b) and in the treatment of Tiapamil (600 mg) increased forearm blood hypertension (Caruana et al., 1986). There is, flow (2.0 ± 0.7 to 2.7± 1.0 ml 100 ml-m min-1) however, little information on the peripheral finger blood flow (5.1 ± 1.7 to 6.7 ± 2.8 ml 100 vascular effects of this compound. The study ml-l min-' and skin temperature (32.4 ± 1.7 was therefore undertaken to determine whether to 33.1 ± 1.1° C) at 4 h when compared with the drug had important peripheral vasodilator baseline (P < 0.05) but due to variations in effects and whether it would be appropriate baseline measurements these changes were not to undertake a similar study in patients with significantly different from placebo. Significant Raynaud's syndrome. prolongation of the PR (0.16 ± 0.03 to 0.18 ± Twelve healthy male subjects aged 19-24 0.03 s) and QTc intervals (0.38 ± 0.03 to 0.41 years were studied. Following a 30 min supine ± 0.06 s) however were observed when com- rest period in a temperature controlled room pared with placebo (P < 0.05). There was a (23 ± 0.50 C) baseline measurements of resting tendency for tiapamil to increase supine and heart rate, blood pressure (Hawksley random exercise noradrenaline levels but these did not zero sphygmomanometer), digital skin temper- achieve statistical significance. Maximum tia- ature (thermistor), digital systolic pressure, pamil concentrations were observed at 2 h. finger and forearm blood flow (strain gauge There was no relationship between plasma tia- plethysmography) were made. Blood pressure pamil levels and any of the haemodynamic and heart rate were then measured after a 3 min changes. This study confirmed the effect of period in the standing position. Heart rate was tiapamil on cardiac conduction but the small again measured within 5 s of completing a 3 min increases in peripheral blood flow observed period of exercise which consisted of stepping with this compound would suggest a limited on and off a box 46 cm high at a rate of 32 steps role in patients with Raynaud's syndrome. min-'. Each subject then received a single oral

Caruana, M. et al. (1986). J. cardiovasc. Pharmac., Gmeiner, R. et al. (1979b). Eur. J. clin. Pharmac., 8, 1074. 16, 155. Gmeiner, R. et al. (1979a). Eur. J. Cardiol., 9, 77. Heizmann, P. et al. (1984). J. Chromatogr., 310, 119.

Comparison of topical betaxolol, carteolol, Betaxolol (B) (cardioselective antagonist), metipranolol and saline on intraocular carteolol (C) (non-selective partial agonist) and pressure in normal volunteers metipranolol (M) (non-selective antagonist) are 3-adrenoceptor antagonists which have recently S. WRIGHT, D. F. EDGAR, J. H. STEWART- been introduced into Britain for topical treat- JONES & P. TURNER ment of ocular hypertension. We have compared Applied Vision Research Centre, City University, their effects on intraocular pressure (IOP) in London and Department of Clinical Pharmacology, normal volunteers. St Bartholomew's Hospital, London Ten normal subjects of either sex aged 18-23 Proceedings of the BPS, 19-21 December 1988 697P years, with intact corneas who did not wear with S, which produced no significant change. contact lenses took part in this double-blind Mean overall falls in IOP during the 2 h for the study. On four occasions 1 week apart, at the four treatments B, C, M and S were 0.97, 1.73, same time of day, each subject received one of 1.42 and 0.13 mmHg respectively. Differences the following treatments in random order; B between the three active drugs were not signifi- 0.5%, C 1.0%, M 0.1% (marketed doses) and cant. Analysis of variance showed no overall buffered saline (S) 0.43%, one drop (0.03 ml) significant changes in mean IOP in the right being instilled into the conjunctival sac of the untreated eye, although a paired Student's t- left eye. Three readings of IOP were taken in test showed that C produced a significant fall both eyes by non-contact tonometry (Grolman, (1.02 mmHg) compared with saline (0.38 mmHg) 1972) before, and at 10, 20, 30, 45, 60, 90 and (P < 0.05) from 45 to 120 min. This study 120 min after instillation, and the mean values confirms previous observations (Mills, 1987) calculated. that the fall in IOP produced by 3-adrenoceptor Analysis of variance of mean IOP changes in blocking drugs is independent of cardioselectivity the treated left eye over 2 h showed a significant and partial agonism and that significant contra- difference between treatments (P < 0.01), all lateral reduction in IOP can occur after topical three drugs showing a fall in IOP compared instillation in one eye.

Grolman, B. (1972). Am. J. Optom., 49, 464. Mills, K. B. (1987). Res. Clin. Forums, 9, 1.

Use of delayed auditory feedback to assess has been used in the diagnosis of non-organic cognitive function in Parkinson's disease deafness. Surprisingly, the speech of some Parkinsonian patients and stutterers has im- P. W. NICHOLSON"2, C. A. WALKER 3, proved under its influence. We report a novel J. DICKINS', C. J. A. O'NEILL', S. G. BOWES', use of DAF, as an objective test of cognitive A. A. DESMUKH"3, S. M. DOBBS' & function which does not require the exercise of R. J. DOBBS' motor skills. 'Divisions of Clinical Sciences and Bioengineering, We studied 139 normal volunteers, aged 30- Clinical Research Centre, Northwick Park Hospital, 89 years (mean 58 years) and 42 patients with Harrow, HAl 3UJ, 2University College and Middlesex idiopathic Parkinson's disease, aged 52-85 School of Medicine, London WlP 6DB and 3School years (mean 72 years). The increase produced of Pharmacy, Brunswick Square, London WC1N lAX by DAF in the time taken to repeat a series of five short sentences after the observer was Some of the mental changes seen in Parkinson's significantly greater in the patients (66%) than disease are due to co-existent depression and/ in the normals (49%), (analysis of variance, P or dementia, the nature and extent of a more = 0.034). A shorter delay in feed back (1/6 vs specific 'bradyphrenia' being controversial. A 1/3 s) had a greater disruptive effect (56 vs 47%, simple, objective measure of the latter would P = 0.013), the effect being similar in patients be useful in assessing both desired and un- and normals. There was no interaction between wanted effects of medication. It would also be subject group and DAF delay. Age had no useful diagnostically, especially in old age where effect on the results of the test. The greater depression and dementia are common. The disruptive effect of DAF in the patients during relative performance of normals and Park- this exercise may reflect an inability to shift insonian patients in simple and choice reaction (Lees & Smith, 1983) or to develop an appro- time tests differ (Bloxham et al., 1984), but priate (Frith et al., 1986) mental 'set' under severely affected patients may be unable to changing conditions. The prolongation of speech execute the required motor task. Delayed audi- produced by DAF during the simpler exercises tory feedback (DAF) involves extending the of counting 1 to 20, and reading single words time between the utterance of speech and its was similar in patients and controls. Further auditory perception. This slows speech and work is necessary to determine whether DAF induces errors. Subjects listen to their own voice and reaction time tests are complimentary via headphones. The circuitry from the micro- in those capable of performing both and to phone is designed to give direct or delayed feed- measure any influence on them of depression back and the voice is recorded on tape. DAF and dementia. 698P Proceedings of the BPS, 19-21 December 1988

Bloxham, C. A. et al. (1984). Brain, 107, 371. Lees, A. J. & Smith, E. (1983). Brain, 106, 257. Frith, C. D. et al. (1986). J. Neurol. Neurosurg. Psychiat., 49, 661.

Influence of pretreatment with oxybupro- screen at fixed magnification, from which the caine on pupillary response to phenylephrine diameters were determined. Subjects were dark in human volunteers adapted for 1.5 min before each pupil measure- ment. Changes in mean pupil diameter over S. DANIELS, D. F. EDGAR, J. H. STEWART- 2 h were subjected to analysis of variance and JONES & P. TURNER showed statistically significant differences be- Applied Vision Research Centre, City University, tween the three treatments in both eyes (P < London and Department of Clinical Pharmacology, 0.05). P 0.12% and 2.5% produced dose- St Bartholomew's Hospital, London EClA 7BE related mydriases compared with S in the right eye, mean increases in pupil diameters over 2 h Pretreatment with a topical anaesthetic can being 0.13 and 0.45 mm respectively. S and 0 enhance the mydriatic effect of a directly acting produced no significant changes in pupil dia- sympathomimetic amine (Lyle & Bobier, 1977). meter, but between-eyes comparison showed We have examined the influence of oxybupro- that 0 significantly increased the mydriasis pro- caine hydrochloride (0) on the mydriatic action duced by P 0.12% (P < 0.01) and P 2.5% (P < of phenylephrine (P) in 10 normal volunteers 0.05) in the left eye, the mydriases being 0.25 of either sex, aged 20-27 years. Each subject and 0.71 mm respectively. attended on three occasions at least 2 days apart, This study has shown that use of 0 prior to at the same time of day. On each visit, one drop instillation of P enhances its mydriatic effect. (0.03 ml) of 0 (0.4%) was instilled into the The mechanism is unknown, but is of rapid conjunctival sac of the left eye. After 3 min, onset, as only 3 min elapsed between instilla- one drop of P 0.12%, P 2.5% or isotonic saline tion of the two drugs. Clinical implications are (S) was instilled into the conjunctival sacs of uncertain, but if other drug effects are enhanced both eyes. Treatments were administered caution must be exercised in pretreatment with double-blind and randomised. Pupil diameters local anaesthetic. Noncontact tonometry, which of both eyes were measured before and 10, 20, does not employ an anaesthetic, does not appear 30, 40, 50, 60, 70, 80, 90, 105 and 120 min after to influence the action of P (Ramsden et al., treatment by infra red pupillometry, the image 1985). of both eyes being projected on to a television

Lyle, W. M. & Bobier, W. R. (1977). Am. J. Optom. Ramsden, R. J. et al. (1985). Int. J. clin. Pharm. Physiol. Opt., 54, 276. Res., 5, 213.

The interaction between tropicamide et al., 1986). We conducted a study to investigate 0.01% and timolol 0.25% on intraocular the interaction between topical 0.01% tropic- pressure amide, a short acting anticholinergic drug, and timolol 0.25% on intraocular pressure in normal M. R. AL-SEREITI & P. TURNER human volunteers, Department of Clinical Pharmacology, St Bartholo- Eight healthy volunteers took part in the study mew's Hospital, London EClA 7BE on four occasions at least 1 week apart. On each occasion, each volunteer received two eye drops The mechanism of the ocular hypotensive action (30 min apart) of placebo + placebo, placebo of timolol is not clear. It has been reported that + timolol, tropicamide + placebo or tropic- a low topical dose (0.1 ml of 1.43 nM) of atro- amide + timolol in the left eye in a randomised pine inhibited the ocular hypotensive action of double-blind cross-over balanced design based timolol in rabbits, suggesting that a cholinergic on two four-by four latin squares with no treat- mechanism is involved in this action (Alkondon ment in the right eye. Intraocular pressure was Proceedings of the BPS, 19-21 December 1988 699P measured by non contact tonometry just before eye (untreated). Intraocular pressure in both the instillation of the first and second eye drops eyes was reduced significantly by tropicamide and then every 30 min for 3 h. + timolol (-1.9 mmHg) (F(l, 175) = 54.8, The data were analysed using multiple linear P < 0.0001) in the left and (-0.7 mmHg) (F regression with the pre-second dose intraocular (1,175) = 10.9, P < 0.001) in the right. Tropic- pressure value included as a continuous inde- amide + placebo had no significant effect on pendent variable together with treatment, time intraocular pressure in the treated eye but re- of measurement and subjects using the dummy duced it significantly (-0.6 mmHg) (F(1,175) = variable technique. 7.8, P < 0.01) in the non treated eye. There Considering all the post-second dose measure- was no significant difference beween the ocular ments compared with placebo, intraocular pres- hypotensive effect of placebo + timolol and sure was reduced significantly by both placebo tropicamide + timolol in the treated eye + timolol (-1.7 mmHg) (F(1,175) = 44.9, P (F(1,175) = 0.5, P = NS) with a significant < 0.0001) in the left eye (treated) with no signi- difference in the untreated one (F(1,175) = 4.8, ficant effect on the right eye (untreated). Intra- P < 0.05). ocular pressure in both eyes was reduced signi- The result of this study shows that there is no ficantly by tropicamide + timolol (-1.9 mmHg) interaction between timolol and tropicamide (F(1,175) = 44.9, P < 0.0001) in the left eye eye drops, at the concentrations used, on intra- (treated) with no significant effect on the right ocular pressure in normal human subjects.

Alkondon, M. et al. (1986). J. Pharm. Pharmac., 38, 319.

'I've no idea what they sent me out on, nature of medical condition, educational back- Doctor!' Would an information booklet at ground and time between discharge and inter- discharge help? view. The booklet patients were taking fewer (mean 3.7) medications than the control patients D. A. SANDLER*, S. T. GARNER & A. FELLOWS (mean 4.3) but there was no significant differ- Departments of Medicine and Pharmacy, University ence. The majority of both groups of patients Hospital, Nottingham NG7 2UH knew why they had been in hospital (B-100%; C-84%; P < 0.01, chi square test), the name of A new system has been devised, whereby an the consultant in charge (B-98%; C-85%; P < Interim Discharge Letter (containing details of 0.05) and the ward they vere on (B-87%; the patient's recent admission to hospital) and a C-80%; P not significant [NS]). When asked to prescription for discharge medications (listing name their tablets, 85% of booklet patients the names, strengths, frequencies, and reasons could name all their tablets correctly, compared for all items, and action to take when supply with 44% of controls (P < 0.001). Ninety-four runs low) is imprinted onto a card-based book- percent of booklet patients recalled the correct let. The top copy of this information is delivered frequency of all their medication compared by the patient to their general practitioner, and with 55% of controls (P < 0.001). Booklet the patient keeps the booklet. patients recalled the strength of all medication Patients were assigned either to receive a in 62% of cases compared with 31% of controls booklet or to act as controls. All patients were (P < 0.01) and 87% of booklet patients had interviewed by face-to-face questionnaire at some idea of the reason for all their treatment their first outpatient attendance after discharge compared with only 38% of control patients (P to determine what they recalled of their admis- < 0.001). sion and treatment. Reference to the booklet, Most booklet patients (98%) indicated that lists or tablet bottles were encouraged. Differ- they had or would take the correct action (to ences between the two groups were tested with continue or stop) when each of their medications the chi square. ran low, as did 71% of control patients (P < 143 patients entered into the study, 19 have 0.01). A minority of patients (B-34% C-18%) been withdrawn and 102 have thus far com- brought all of their medications with them when pleted the protocol: 47 patients assigned to re- attending clinic and this difference was not ceive a booklet (B) and 55 patients to act as significant. controls (C). In this pilot study of the feasibility of giving The patients were well balanced for age, sex, patients an information booklet at the time of 700P Proceedings of the BPS, 19-21 December 1988 discharge, the possession of such a booklet be considered useful to the doctor seeing them appears to enhance the recall of aspects of the in the clinic. patient's admission and treatment which may

The influence of levodopa on gastric prior to a second period of rapid emptying. In emptying in man the eighth subject the plateau was not preceded by a measurable emptying phase. Thus the time D. R. C. ROBERTSON, A. G. RENWICK, to a 90% decrease in counts in the stomach was N. CROSS, B. S. MACKLIN, D. G. WALLER, prolonged by levodopa from 52 ± 12 min to 98 N. D. WOOD & C. F. GEORGE ± 65 min (P < 0.01). The time to the peak Southampton Clinical Pharmacology Group, concentration of paracetamol was not signifi- Southampton General Hospital, Southampton cantly affected by levodopa (control 23 ± 12 min; with levodopa 28 ± 19 min). However the Previous studies have reported multiple peaks maximum plasma concentration of paracetamol in the plasma concentration-time curve of levo- was significantly reduced by levodopa (control dopa following oral administration, which have 33.1 ± 11.0 ,ug ml-'; with levodopa 24.2 ± 6.5 been assumed to be due to erratic gastric empty- ,ug ml-' P < 0.05) which is consistent with ing (Evans et al., 1981). Since multiple peaks levodopa causing incomplete initial emptying. are rarely seen with other rapidly absorbed The total area under the paracetamol plasma drugs, we have studied the influence of levo- concentration-time curve was not affected by dopa on gastric emptying in eight healthy volun- levodopa (control 4589 ± 653 ,ug ml-1 min; with teers. After an overnight fast, each volunteer levodopa 4694 ± 822 ,ug ml-1 min). After levo- received on two occasions, separated by at least dopa five out of the eight subjects showed clear 1 week, a solution containing 1.5 g of para- evidence of second peaks in both the para- cetamol, as a pharmacological marker and cetamol and levodopa concentration time 99mTc-DTPA, as a -y marker of gastric empty- curves which correlated closely (P < 0.01) with ing. Oral carbidopa (100 mg) was given 1 h respect to time. In these five subjects a cor- before paracetamol and DTPA. On one of the relation (P < 0.05) was also found for the times study days levodopa (125 mg) was given in to the trough concentrations of paracetamol solution with the paracetamol and DTPA. and levodopa prior to the second peak. The Without levodopa -y camera imaging showed a time to the end of the plateau on the scan also rapid mono or bi-exponential gastric emptying correlated with the time of the trough para- pattern. Levodopa caused a small but signifi- cetamol concentration (P < 0.05). cant increase in the initial half-life of emptying These data demonstrate that levodopa alters (mean ± s.d., 16 ± 10 min c.f. 6 ± 3 min P < the pattern of gastric emptying and that this is 0.05). This was followed by a plateau phase of the cause of the multiple plasma concentration negligible emptying in seven of the eight subjects peaks reported following its oral administration.

Evans, M. A. et al. (1981). Neurology, 31, 1288.

Growth hormone secretion human Dopaminergic and noradrenergic neurones by of the tubero-infundibular pathway are those females in response to apomorphine which are chiefly responsible for the mediation challenge is markedly affected by menstrual of excitatory influences upon growth hormone cycle phase (GH) secretion in man. In this study, the effect of menstrual cycle phase upon apomorphine A. WIECK, A. D. HIRST*, R. KUMAR, (APO)-stimulated GH secretion was investi- S. A. CHECKLEY & I. C. CAMPBELL gated. We have studied GH responses to APO Departments of, Psychiatry and *Biochemistry Insti- in four women (mean age 33.2 ± 2.7 (s.e. tute of Psychiatry, Denmark Hill, London SES 8AF mean)) in both the follicular and luteal phases. Proceedings of the BPS, 19-21 December 1988 701P Two subjects had a history of puerperal mated by the size of the mean sum of plasma psychosis and were tested more than 1 year GH concentrations measured over the 90 min after recovery: the other two had had no psychi- following APO injection. The mean post-injec- atric illness. None of the women had taken oral tion peak in plasma GH concentrations observed contraceptives for 3 years, and the two patients in the luteal phase is also approximately four- had been free from psychotropic medication for fold greater than that observed in the follicular 1 and 4 years respectively. Approval from the phase. Maudsley Hospital Ethics Committee was Neuroendocrine challenge tests such as APO obtained, as well as informed consent from the stimulation of GH secretion are widely used to subjects. obtain an indirect measure of central receptor After resting the subjects for 1 h, blood function in psychiatric patients. The reasons for samples were taken every 15 min over a period the differences in APO-induced GH release of 30 min for measurement of baseline plasma between follicular and luteal phases of the GH levels. Following injection of APO (5 p.g menstrual cycle are presently unclear but may, kg-', s.c.), blood was sampled every 15 min for for example, be related to alterations in GH 90 min. Plasma GH levels were assayed im- synthesis or dopamine receptor status. Our munoradiometrically using a proprietary kit results show that in studies of the GH response (Boots-Celltech, UK). to APO, in addition to matching subjects with The GH secretion elicited by APO during the normal controls of the same sex, particular care luteal phase is four-fold greater than that must be taken to study female probands in the obtained during the follicular phase, as esti- same phase of the menstrual cycle.

Table 1 Plasma GH concentrations (ng ml-' ± s.e. mean, n = 4). Sum of GH concentrations Post-injection in post-injection Baseline peak plasma samples Luteal phase 0.17 ± 0.06 10.8 ± 0.75 33.6 ± 2.90 Follicular phase 0.19 ± 0.05 2.82 ± 1.48 8.40 ± 4.71

(OCITT) was determined in five placebo con- Oro-caecal transit time in man unaffected trolled two part cross over studies using the by 5-HT3 antagonism: a comparison of lactulose/breath hydrogen method (Bond & BRL 24924 and BRL 43694 Levitt, 1977). This method relies on the obser- vation that lactulose passes unaltered through D. H. STANIFORTH the small bowel, but is broken down by caecal Beecham Clinical Pharmacology Unit, West Middle- flora to produce small amounts of hydrogen. sex University Hospital, Twickenham Road, Isleworth, An increase of 15 ppm in breath hydrogen was Middlesex TW7 6AF used to indicate that the head of the test meal had reached the large bowel and the time taken BRL24924 is a stimulant of gastrointestinal for the rise as a measure of OCiT. Three studies motility in man (Rapeport & Thompson, 1987; were carried out on BRL24924 at doses of 0.3, Staniforth & Corbett, 1987). The drug is thought 0.4 and 1 mg. BRL43694 was investigated in to act predominantly by facilitating acetylcholine two studies at doses of 50 and 200 ,ug kg-' these (ACh) release from the myenteric plexus, pos- doses being chosen because they have been sibly by activating a 5-HT-like receptor (Sanger, shown to be effective in preventing cytotoxic 1987). In this study the gastrointestinal stimulant drug induced emesis (Carmichael et al., 1988). actions of BRL24924 have been compared with OCTl was assessed immediately after admin- the actions of BRL43694, a more potent and istration of the drug which was given as an selective 5-HT3 receptor antagonist which does infusion over 3 min in the case of BRL24924 not facilitate myenteric ACh release (Fake et and 30 min in the case of BRL43694. BRL24924 al., 1987). All subjects were healthy volunteers. reduced the oro-caecal transit time compared Each of these experiments involved a separate with placebo treated control whereas BRL43694 group of subjects. Oro-caecal transit time did not (Table 1). 702P Proceedings of the BPS, 19-21 December 1988 Meleagres et al. (1987) have shown that ICS caecal transmit time whereas BRL24924, a 205-930, a selective and potent 5-HT3 receptor 5-HT3 antagonist with only a quarter the potency, antagonist reduces OCT1 in man at a dose of reduces OCT1 in a dose dependent manner. 20 mg i.v. about twice the dose of metoclo- It is concluded that 5-HT3 antagonism is not pramide required to produce a similar action relevant to the gut motility enhancing properties (Staniforth, 1987). BRL43694, a potent 5-HT3 of either metoclopramide or BRL24924. antagonist, is here shown not to reduce oro-

Table 1 Effects of BRL24924 and BRL43694 on oro-caecal transit assessed by the lactulose/ breath hydrogen method Oro-caecal transit time (min) Control Drug % Number of Drug and dose Mean (s.d.) Mean (s.d.) change subjects P* 0.3 mg 135.5 (43.5) 102.5 (15.5) -24.3 10 = 0.05 BRL24924

BRL24924 154.2 (55.1) 105.8 (42.1) -31.3 6 0.01 1.0 mg 116.7 (45.2) 68.3 (24.4) -41.5 6 0.05 50 ~Lg kg-1 BRL43694 160.0 (69.1) 175.0 (73.8) +9.4 10 = 0.5 20B3g kg 162.5 (53.8) 175.8 (86.5) +8.2 12 N.S.

*paired t-test

Bond, J. H. et al. (1977). J. lab. clin. Med., 85, 546. Sanger, G. S. (1987). Br. J. Pharmac., 91, 77. Carmichael, J. et al. (1988). Br. med. J., 297, 110. Staniforth, D. H. (1987). Eur. J. clin. Pharmac., 33, Fake, C. S. et al. (1987). Br. J. Pharmac., 91, 335P. 55. Meleagres, L. et al. (1987). Gut, 28, A1373. Staniforth, D. H. & Corbett, R. (1987). Br. J. clin. Rapeport, W. G. et al. (1987). Br. J. clin. Pharmac., Pharmac., 24, 263P. 24, 263P.

A single dose of theophylline prolongs intestinal transit but not gastric emptying three males, aged 33 ± 2.8 years, mean ± s.d. weight 62.7 ± 13.6 kg, height 166 ± 9.5 cm) J-C. RENONDIN, J. A. SUTTON & M. FRASER were recruited after giving informed consent Clinical Pharmacology Unit, Roussel Laboratories and with the sanction of the institutional ethics Ltd, Swindon committee. GE of 420 ml dilute orange squash drunk 0.5 h after dosing was measured by the Theophylline relieves asthma by relaxation of epigastric impedance technique (McClelland & bronchial smooth muscle but unwanted effects Sutton, 1985). The MCTT of lactulose (10 g such as nausea may be caused by a similar effect added to the test meal) was measured by the on gastrointestinal (GI) smooth muscle (Jacobs breath hydrogen method (Bond & Levitt, 1975) et al., 1976). This study examined the hypothesis using a 15 ppm rise in hydrogen concentration that an effect upon GI smooth muscle function as the criterion for arrival of lactulose in the of a standard, single dose (375 mg) on gastric caecum. emptying (GE) and mouth-colon-transit-time For GE there was no difference between of intestinal contents (MCTI) would be detect- theophylline and placebo (median GE 13.5 min, able in normal volunteers. range 7.5 to 29 vs 15.5 min, range 9.0 to 25.5 Fourteen healthy volunteers (11 females and respectively). Proceedings of the BPS, 19-21 December 1988 703P For MCIT a significant treatment difference with non-nauseated subjects; therefore reduced was detected (Friedman's test, P < 0.01). transit rates were not related exclusively to (Theophylline median was 114.0, inter-quartile nausea. range 110 to 145 min and placebo median 89.0, A 375 mg dose of theophylline significantly inter-quartile range 60 to 105 min, P < 0.01, slowed MCT1 in normal volunteers but not GE Wilcoxon's paired test). of a liquid test meal. The method is therefore Three volunteers reported nausea after theo- a volunteer model capable of detecting un- phylline but their differences between active wanted GI smooth muscle activity in phospho- and placebo GE and MCTT were comparable diesterase inhibitors.

Bond, J. H. & Levitt, M. D. (1975). J. lab. clin. McClelland, G. R. & Sutton, J. A. (1985). Gut, 26, Med., 85, 546. 607. Jacobs, M. H. et al. (1976). J. Am. med. Ass., 235, 1983.

Oral activated charcoal in protoporphyria material (18 mmol/5 g sachet) limited the amount with liver damage given to 10-15 g 24 h-1. Separate later admin- istration of Carbomix (Penn Pharmaceuticals) A. GORCHEIN, S. K. F. CHONG & for 4 months resulted in less reduction of the A. P. MOWAT protoporphyrin level to 800 nmol 1-1, and a Department of Clinical Pharmacology and Thera- ceiling effect was noted with 30 g 24 h-1. Re- peutics, St Mary's Hospital Medical School, London introduction of Medicoal resulted in an initial W2 lNY and Department of Child Health, King's decrease of the protoporphyrin level to 450 nmol College Hospital, London SE5 9RS I-1, similar to the value previously obtained, but this increased over the next 2 months to - Protoporphyria results from deficiency of the 800 nmol 1-1. Administration of SuperChar last enzyme of haem synthesis, ferrochelatase. (Gulf Bio-systems) at doses up to 60 g 24 h over It is characterised by cutaneous photosensitivity the following 11 weeks was associated with an and usually only mild impairment of liver func- increase of the plasma level of protoporphyrin tion. Rarely, liver damage is severe with rapid to - 2000 nmol 1-1 which was not reduced by progression to terminal cirrhosis due to deposi- re-introduction of Medicoal for 6 weeks. tion of excess photoporphyrin, presumed to be It is concluded that oral activated charcoal mainly of erythroid origin. No treatment is then can lower the plasma protoporphyrin level in available other than liver transplantation. protoporphyria and that available charcoal Porphyrins undergo enterohepatic circulation preparations differ in their effectiveness. Medi- and are avidly adsorbed in vitro by activated coal at only 10-15 g appeared to be more effec- charcoal (Tishler & Winston, 1985). Isolated tive than Carbomix, but it was not possible to reports of the therapeutic use of oral activated draw conclusions about the relative value of charcoal in certain porphyrias have given en- SuperChar. couraging results (Pimstone et al., 1987). The major factor likely to determine success The effect on the plasma protoporphyrin level with this type of treatment is the quantity of of oral activated charcoal was therefore studied protoporphyrin which can be excreted by the over a 1 year period in a 5 year old subject with liver into the gut. When this is already severely protoporphyria and cirrhosis. Three different limited by liver disease, continuing tissue de- charcoal preparations were evaluated. position of protoporphyrin will result in a vicious Plasma protoporphyrin was reduced from spiral of decreasing effectiveness of charcoal as pretreatment levels of 1200-1750 nmol 1-1 to liver function decreases. Progression of liver 400 nmol 1-1 by treatment with Medicoal disease in this patient has not been halted by (Lundbeck) for 9 days. The Na+ content of this charcoal treatment.

Pimstone, N. R. et al. (1987). New Engl. J. Med., Tishler, P. V. & Winston, S. H. (1985). Methods 316, 390. Find. exp. clin. Pharmac., 7, 485. 704P Proceedings of the BPS, 19-21 December 1988

Nature and time course of piroxicam point Lanza Scale (Lanza et al., 1980) and a induced injury to gastric mucosa in man visual analogue scale. The principal site of mucosal injury was the I. W. FELLOWS, N. K. BHASKAR & gastric body. Overall, endoscopic evaluation of C. J. HAWKEY body injury correlated with bleeding (r = 0.40, Department of Therapeutics, University Hospital, P = 0.004 for Lanza score and r = 0.33, P = Nottingham 0.02 for visual analogue scale), but there were important differences in time course. Endos- Piroxicam is associated with peptic ulceration copically, haemorrhagic mucosal lesions de- but paradoxically does not enhance acute gastric veloped rapidly, mainly in the body (median bleeding in healthy humans (Collins & Notari- Lanza grade 0, interquartile range 0-0.5), anni, 1984). However, the drug has a long half- before; 3.5 (2-4) 10 h after the first dose, (P < life and short-term studies may be inadequate 0.01) but did not subsequently increase further to determine its effect on the gastric mucosa. (3.5 (0.5-4) on day 21). However, intraluminal This study was designed to investigate the nature bleeding (RIl 10 min-1; means and 95% con- and time course of piroxicam-induced gastric fidence limits) only rose significantly by day 21: mucosal injury. 4.4 (1.5-13.2) at day 21 vs 1.3 (0.6-2.8), base- Ten healthy volunteers aged 21-25 years line (P < 0.02); vs 1.6 (0.8-3.6) at day 1 (P < (eight male) gave informed written consent to 0.05); vs 1.5 (0.6-3,5) at day 5 (P < 0.02); and the procedure which was approved by the vs 1.9 (0.7-5.1) at day 10 (P > 0.05). One Medical School Ethics Committee. Each volun- subject developed a shallow 3 mm diameter teer took piroxicam 10 mg twice daily orally for prepyloric ulcer at day 21; this healed spon- 21 days. All were non-smokers and the only taneously within 2 weeks. permissible concomitant drug administration Endoscopically-assessed gastric mucosal was the oral contraceptive. Gastric microscopic injury and bleeding induced by piroxicam are bleeding (Hawkey et al., 1988) was quantified dissociated in time. Acute injury by piroxicam and upper gastrointestinal fibreoptic endoscopy differs from aspirin in that it mainly affects the was performed without sedation before and gastric body and causes delayed intraluminal 10 h after the first dose and after 5, 10 and 21 bleeding. Ulcerogenicity and bleeding are days consumption of piroxicam. Mucosal damage separate targets for prophylaxis. was assessed endoscopically using a modified 5

Collins, A. J. & Notarianni, L. J. (1984). J. int. Med. Lanza, F. L. et al. (1980). New Engl. J. Med., 303, Rev., 12, 179. 136. Hawkey, C. J. et al. (1988). Aliment. Pharmac. Ther., 2, 245.

Effects of nicardipine on the metabolic hypertension. Two provocative tests were em- responses to food and exercise ployed: a standard meal (containing 64 g carbo- hydrate, 25 g fat, 19 g protein) and a standard- J. H. AHMED, H. L. ELLIOTT, C. A. HOWIE, ised exercise protocol (25% and 50% of pre- J. HOSIE & J. L. REID determined exercise capacity each for 10 min). University Department of Materia Medica, Stobhill Blood samples were collected at 15, 30, 60, 120, Hospital, Glasgow G21 3UW 180, 240 min after the meal for the following: total cholesterol and triglyceride, lipoprotein Dihydropyridine calcium antagonists have been cholesterol fractions, insulin and glucose. A claimed to modify carbohydrate metabolism second dose of drug or placebo was admin- (Charles et al., 1981). We have studied the effect istered 6 h after the morning dose and the exer- of nicardipine (NIC) on metabolic responses to cise protocol was performed 1 h after this dose food and exercise in essential hypertension. In with blood sampling before and after exercise a placebo controlled double-blind randomized for lipids, lipoproteins and other plasma hormone crossover study, the metabolic and hormonal levels. Time and treatment effects were evalu- effects of treatment with NIC (30 mg three ated by univariate repeated measures analysis times daily for 4 weeks) have been evaluated in of variance. Data are presented as mean (± s.d.) seven patients with mild to moderate essential in Table 1 which shows the baseline measure- Proceedings of the BPS, 19-21 December 1988 705P ments with the response represented by the hormonal and metabolic indices following food area under the plasma concentration profiles or exercise. These results, which are comple- (conc. unit min- ) for each parameter. mentary to the findings of conventional long- Supine diastolic blood pressure fell from 96 term studies, indicate that NIC has no significant + 10 to 85 ± 10 mmHg (P < 0.05) on nicardi- effect on serum lipids or on hormonal and pine. There were no significant differences be- metabolic responses to food and exercise. tween NIC and placebo for any of the measured

Table 1 Cholesterol HDL LDl VLDL (mmol 1-1) (mmol 1-') (mmol 1-') (mmol h-1) Basal A UC Basal A UC Basal A UC Basal AUC a. Meal Control 5.9 1400 1.2 280 3.9 958 0.6 159 (1.4) (320) (0.3) (66) (1.0) (254) (0.3) (60) NIC 6.0) 1440 1.3 296 4.0 953 0.7 193 (1.3) (310) (0.2) (55) (1.2) (275) (0.6) (155) Triglyeride Glucose Insulin (mmol 1-1) (mmol 1-1) (mu 1-') Basal AUC Basal AUC Basal AUC Control 1.8 545 5.4 1510 12.4 1400 (0.8) (252) (1.1) (258) (10.0) (11400) NIC 2.2 638 5.4 1540 13.5 12000 (1.5) (396) (0.9) (265) (11.0) (8320) FFA Cortisol Glucagon Lactate (,umol 1 1) (nmol 1-1) (ng ml-) (mg 100 ml-1) b. Exercise Basal AUC Basal AUC Basal AUC Basal AUC Control 448 16146 220 6642 51 1321 19.7 787 (104) (8441) (72) 2085 (40) (508) (2.6) (172) NIC 501 19778 285 9273 40 1096 17.2 642 (211) (6302) (119) 3458 (15) (191) (4.4) (305)

Charles, S. et al. (1981). Br. med. J., 283, 19.

A two-compartment pharmacokinetic estimation of the ER of ICG without hepatic model fails to predict the hepatic extraction venous catheterisation (Grainger et al., 1983). ratio of indocyanine green However, studies in the rat (Burns et al., 1989) and in man (Clements et al., 1987) have cast E. BURNS, C. E. BALL, D. R. TRIGER' & doubt on the validity of the model, though in N. D. S. BAX the studies performed in man assay limitations University Departments of Pharmacology and Thera- may have influenced the estimates obtained. peutics and of 'Medicine, Royal Hallamshire Hospital, Therefore we have compared estimates of the Glossop Road, Sheffield ER of ICG obtained by direct transhepatic sampling with those obtained using the phar- The accurate estimation of hepatic blood flow macokinetic model. using indocyanine green (ICG) neccessitates Six patients with liver disease gave written measurement of the hepatic extraction ratio informed consent to the study which was ap- (ER). The use of a pharmacokinetic model to proved by the Hospital Ethics Committee. The derive this variable has been described allowing ICG ER was estimated directly by transhepatic 706P Proceedings of the BPS, 19-21 December 1988

sampling after a combination of an ICG bolus the disposition of ICG, from which the ER was (5 mg; i.v.) and infusion of ICG (0.25 mg min-) calculated. Table 1 shows the two estimates of to steady state. Between 2 and 14 days later the the ICG ER. patients were given an i.v. bolus of ICG (0.5 The reason for the disagreement in estimates mg kg-') and peripheral venous samples were of the ICG ER may be that the elimination of collected for 2 h. Plasma ICG concentrations ICG is inadequately described by a two-com- were measured by the sensitive and specific partment model. The use of a short sampling h.p.l.c. method of Christie et al. (1986) (lower period and the relatively non-specific and in- limit of detection 10 ng ml-'). The ER was sensitive spectrophotometric assay may not calculated from the hepatic and peripheral have allowed the terminal phase of ICG elimi- venous ICG concentrations at steady state. The nation to be characterised. Thus the pharmaco- pharmacokinetic model was also used to esti- kinetic model failed to predict the ER of ICG mate the ER. The parameters describing the bi- accurately, and cannot be used to provide esti- exponential ICG plasma concentrations-time mates of hepatic blood flow in liver disease as curve were obtained using ELSFIT. These has previously been suggested (Navasa et al., parameters were used to derive the compart- 1987). mental microrate transfer constants describing

Table 1 Directly measured Calculated value of ER Patient value of ER (pharmacokinetic model) 1 0.23 0.77 2 0.25 0.61 3 0.41 0.77 4 0.23 0.86 5 0.34 0.82 6 0.61 0.84

Burns, E. et al. (1989). Clin. Sci. (in press). Clements, D. et al. (1987). J. Hepatol., 5, 282. Christie, J. P. et al. (1987). Br. J. clin. Pharmac., 21, Grainger, S. L. et al. (1983). Clin. Sci., 64, 207. 568P. Navasa, M. et al. (1987). J. Hepatol., 3, S29.

Calcium channel antagonists and of particular interest at the present time is the cyclosporine metabolism use of Ca"+ channel antagonists in renal allo- graft recipients since diltiazem has been demon- D. J. BACK, J. F. TJIA & A. M. BRECKENRIDGE strated to exert a beneficial effect on early graft Department of Pharmacology and Therapeutics, function (Kohlaw et al., 1988). Ca++ channel University of Liverpool, P.O. Box 147, Liverpool antagonists are agents of widely varying struc- L69 3BX ture and it is important to ascertain how they affect CSA metabolism and hence CSA blood Cyclosporin (CSA) is a unique immunosup- levels. We have investigated the effects of dil- pressant used to prevent the rejection of trans- tiazem, verapamil, nifedipine and nicardipine planted organs and to treat diseases of auto- on CSA metabolism in human liver microsomes immune origin. CSA undergoes extensive hepatic in vitro. metabolism in animals and man to mono- and Histologically normal human livers (n = 4) dihydroxylated as well as N-demethylated were obtained from renal transplant donors. products. The major primary oxidative meta- Microsomal incubations (for 30 min) contained bolites are Ml, M17 and M21. Further oxidation [3H]-CSA (40 ,umol; 0.2 ,iG), NADPH (1 mM), of Ml or M17 generate the dihydroxylated microsomal protein (3 mg), MgGl2 (5 FM), metabolites. Since the introduction of CSA a EDTA (1 mM), KCl (1 mM), 1/15 M phosphate large number of clinically important interactions buffer (pH 7.4) to a final volume of 2.5 ml. with other drugs has been reported. One area In some incubations, diltiazem, verapamil, Proceedings of the BPS, 19-21 December 1988 707P nifedipine and nicardipine (5, 10, 20, 50 F.M) Nicardipine produced marked inhibition of were added. CSA and metabolites were ex- CSA metabolism. In contrast, nifedipine caused tracted into ether (6 ml) and quantified by less than 10% inhibition of M21 and M17 even h.p.l.c. Separations were performed at 760 C on at the highest concentration. Diltiazem data a Partisil ODS-3 (25 cm x 0.46 cm) column. were comparable with nifedipine (at 50 FM, 21% The mobile phase used was acetonitrile: water and 16% inhibition of M17 and M21 respec- (67:33) and the flow rate 1.5 ml min-1. Meta- tively. Verapamil (50 FM) produced 30% and bolites (Ml, M17, M21) were identified on the 28% inhibition of M17 and M21. basis of the retention time of the authentic On the basis of these data there are clear dif- compounds. Table 1 shows the effect of nicardi- ferences in the metabolic interaction potential pine and nifedipine on the production of the of the various Ca++ channel antagonists with two major metabolites M17 and M21. CSA.

Table 1 % of metabolites (mean ± s.d.) M17 M21 Control 12.1 ± 1.9 5.2 ± 0.9 Nicardipine (>tM) 5 7.1±2.4 3.1±0.9 10 5.6±2.2 2.2±0.6 20 4.0 ± 1.8 1.7 ± 0.6 50 2.3±0.9 1.1±0.3 Nifedipine (>LM) 5 12.2 ± 1.8 5.6 ± 0.9 10 12.6 ± 2.7 5.7 ± 1.3 20 11.1+3.1 5.0+1.4 50 10.0 ± 2.5 4.5 ± 1.1

Kohlaw, K. et al. (1988). Transplant Proc., 20, Suppl. 2, 572.

Age and the pharmacodynamics and pharmacokinetics of benazepril Treatments were administered at weekly inter- vals and on each study day frequent blood N. J. MACDONALD*, H. L. ELLIOTT, samples were taken for plasma drug levels and C. A. HOWIE & J. L. REID plasma ACE activity and supine and erect Department of Materia Medica, Stobhill General blood pressure and heart rate were measured. Hospital, Glasgow, G21 3UW, Scotland Both ACE inhibitors were generally well toler- ated. Blood pressure fell significantly after both This study investigates the effect of age on the active treatments with mean maximal falls (cor- pharmacodynamics and pharmacokinetics of a rected for changes in blood pressure on placebo) new long-acting non-sulphhydryl angiotensin being numerically greater in the elderly. For converting enzyme (ACE) inhibitor benazepril example, supine blood pressure fell by 17/11 ± (3- ([-ethoxycarbonyl-3-phenyl-(lS)-propybl] 11/9 in the elderly and 9/9 ± 4/8 mmHg in the amino)-2,3,4,5, -tetrahydro-2-oxo-1- (3S) -benz- young after enalapril (95% confidence limits 0 azepine-1-acetic acid monohydrochloride; to 16.3/-6.5 to 10.5) compared with 15/9 ± 9/ (CGS1482A) which is de-esterified to the active 8 in the elderly and 2/6 ± 5/9 in the young after diacid benazeprilat. benazepril (C.I. 5.7 to 20.2/-5.5 to 11.5). This Nine healthy normotensive males (21-39 apparently greater effect in the elderly may be years) and nine healthy normotensive elderly a consequence of their higher baseline blood subjects (66-76 years; seven male and two pressures (147/80 ± 18/9 vs 127/2 ± 13/ female) participated in a double-blind crossover mmHg) since analysis of covariance, using initial study of the oral administration of single doses pressure as a covariate, did not show a signifi- of 10 mg benazepril, 10 mg enalapril and placebo. cant difference between the two age groups. 708P Proceedings of the BPS, 19-21 December 1988 De-esterification was more rapid for ben- than with enalapril (86%) (1.5 vs 4.5 h) and was azepril than enalapril (tm. 1.5 h vs 4 h) but sustained for several hours after dosing so that there was no age related difference. For both there was greater than 40% inhibition at 24 h drugs the area under the concentration-time after both drugs. curve (AUC(O.) was significantly greater in the Fitting these data to a sigmoid Emax model elderly: 2709 ± 1459 vs 1272 ± 272 nmol 1-1 h for individual subjects (Kelman et al., 1983) for enalaprilat (P < 0.01) and 3867 ± 1340 vs showed no age related differences in the sensi- 2765 ± 776 nmol 1-1 h for benazeprilat (P < tivity of plasma ACE inhibition following either 0.05). Overall, AUC was highest in subjects drug. Overall, the results for benazepril were with the lowest creatinine clearances but the qualitatively similar to those for enalapril. Dif- terminalfelimination half-life (over 30 h for ferences in extent and time course of plasma each driug) was not significantly influenced by ACE inhibition following the two drugs may age. There were no significant differences be- reflect the more rapid conversion of benazepril tween young and elderly for peak drug concen- to its active metabolite, or a lower IC50 for trations, although this tended to be higher for benazeprilat. These differences were not re- enalaprilat in the elderly (199 ± 105 vs 128 + flected in the comparable hypotensive responses 63 nmol 1-1). to the two drugs and their full clinical relevance Maximum inhibition of plasma ACE activity remains to be established. occurred more rapidly with benazepril (98%)

Kelman, A. W. et al. (1983). Br. J. clin. Pharmac., 15, 506.

The serum protein binding of medifoxamine munodiffusion using commercially available plates. S. SALEH, A. JOHNSTON & P. TURNER There was no effect of medifoxamine concen- Clinical Pharmacology, St Bartholomew's Hospital, tration on protein binding over the range 10 ng London ECIA 7BE l-1-100 mg 1-1. Medifoxamine was found to be highly bound to plasma protein, mean binding Medifoxamine is a new monoamine reuptake being 96.6 s.d. 0.58%. There was no relation- inhibiting antidepressant drug (Leger et al., ship between sex or age of the donors and the 1986) which is undergoing clinical evaluation. degree of binding. The ranges of plasma AGP As part of an investigation of its pharmaco- and albumin were 0.1 to 1.8 and 29 to 63 g 1-1 kinetics and pharmacodynamics we have deter- respectively. There was no relationship between mined the extent of its binding to serum proteins. the degree of binding and plasma albumin con- Serum samples were collected from 48 sub- centration (r = 0.14), but there was a highly jects (29 female) and 19-43 years, who had not significant effect of AGP on binding (r = 0.51, taken any drugs for at least 1 week. Serum P < 0.01). samples (1 ml) were dialysed against 1 ml of It has been stated that if drugs are more than isotonic phosphate buffer (pH 7.4) containing 80% protein bound this is likely to be clinically 500 ,ug I1 [14C]-labelled medifoxamine. Dialysis important (Koch-Weser & Sellers, 1976). Muller was performed in duplicate at 370 C for 4 h & Stillbauer (1983) found that basic drugs were using a cuprophan membrane of 11.5 ,um thick- bound exclusively to the same single binding ness. The time to reach equilibrium was estab- site of AGP. Medifoxamine binding would be lished from a separate experiment and found to expected, therefore, to be influenced by serum be 2 h using the serum from one individual. AGP levels and by the presence of other basic Serum al-acid glycoprotein (AGP) and albumin drugs which might displace it. were determined in the samples by radial im-

Leger, J. M. et al. (1986). Psychologie Medicale, 18, Muller, W. E. & Stillbauer, A. E. (1983). Pharma- 2295. cology, 322, 170. Koch-Weser, J. & Sellers, E. M. (1976). New Engl. J. Med., 294, 311. Proceedings of the BPS, 19-21 December 1988 709P

Systemic exposure to a carcinogenic in urine was quantified by a modification of a heterocyclic amine following consumption published procedure (Murray et al., 1988b), of meat utilising gas chromatography mass spectro- emetry. Internal standard, [C1 N!5]MeIQx, was A. R. BOOBIS, S. MURRAY, N. J. GOODERHAM added to the samples which were made basic & D. S. DAVIES and then extracted with ethyl acetate. The Department of Clinical Pharmacology, Royal Post- amines were back extracted into acid and then graduate Medical School, Ducane Road, London derivatised with 3,5-bistrifluoromethylbenzyl W12 ONN bromide. The limit of detection of the assay was 5 pg ml-' urine. Diet has been established as a major factor in Following abstinence from cooked meat for the aetiology of several forms of cancer. One 24 h, no MeIQx could be detected in the control possible mechanism for this is the occurrence of urine samples from any of the subjects. In the carcinogenic chemicals in food. Several such 12 h following the ingestion of the test meal, genotoxic compounds have been identified, MeIQx could be detected in the urine of all of amongst the most potent of which are imidoaza- the subjects (12.37 ± 2.61 ng/12 h mean ± arenes formed from proteins and other natural s.d.). No MeIQx could be detected in the 12- constituents during the normal cooking of meat. 24 h urine sample from any of the subjects. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline MeIQx was measured in samples of the cooked (MeIQx), which accounts for a large part of the meat, to provide an estimate of the amount of mutagenicity of cooked beef, is present at levels the amine ingested. Thus, it was possible to of 1-2 ng g-1 (Murray et al., 1988b). In previous calculate the percentage of the dose recovered studies it was shown that the microsomal fraction in urine. This ranged from 1.8-4.9% (3.25 ± of human liver is very effective at activating 1.11%, mean ± s.d.). MeIQx to a potent mutagen in the Ames/ This study has shown that on ingestion of Salmonella test (Murray et al., 1988a). How- cooked meat, the potent genotoxin MeIQx is ever, it was not known whether MeIQx present absorbed and bioavailable, as indicated by its in cooked meat was bioavailable in man, and excretion in urine. Thus, the potential exists for thus exposed to the enzymes of such activation the activation of the amine to a genotoxic meta- in vivo. The present study was undertaken to bolite in those tissues possessing a suitable mono- answer this question. oxygenase system. MeIQx appears to be absent, Six healthy male volunters agreed to partici- or at least is not absorbed, from a non-meat pate in the study, which had local Research diet. Further, the elimination of MeIQx in man Ethics Committee permission. The subjects is relatively rapid. However, the proportion of were asked to abstain from eating any meat, the dose accounted for in these studies was low. other than the test meal, for 48 h before and The fate of the majority of the compound is not for the duration of the study. Subjects collected yet known. It may not be absorbed, but studies all urine for the 24 h prior to the study in 2 x in animals suggest that this is unlikely (Gooder- 12 h collections. They then ingested approx. ham et al., 1988), and that a more likely ex- 320 g (cooked weight) lean ground beef patties, planation is that it is extensively biotransformed. fried at normal cooking temperatures, together with 400 ml tap water. All urine was collected This work was supported by PHS grant number for the next 24 h, in 2 x 12 h collections. The CA40895-02 from the National Cancer Institute, volume of the urine samples was noted and DHHS and by the Cancer Research Campaign. portions were frozen at -20° C assay. MeIQx

Gooderham, N. J. et al. (1988). Human Tox., 7, 381. Murray, S. et al. (1988b). Carcinogenesis, 9, 321. Murray, B. P. et al. (1988a). Biochem. Soc. Trans., 16, 620. 710P Proceedings of the BPS, 19-21 December 1988

ICI 192605; a potent, selective thromboxane an overnight fast. Blood was collected from an receptor antagonist is orally active in man antecubital vein and platelet aggregation per- formed using the method previously described C. L. JESSUP, R. JESSUP, R. D. STARK & (Jessup et at., 1986). Platelet sensitivity to C. WILLIAMS U-46619 and ADP, measured as the extent of Imperial Chemical Industries PLC, Pharmaceuticals aggregation was determined on three separate Division, Alderley Park, Macclesfield, Cheshire occasions before, and 1, 3 and 8 h after, oral SK10 4TG administration of ICI 192605 or placebo. Statis- tical significance was determined by comparing ICI 192605 (4(Z)-6-[(2,4,5 cis)-2-(2-chloro- agonist log EC50 values from placebo and drug phenyl)-4-(2-hydroxy-phenyl) 1 ,3-dioxan-5-yl]- dosed volunteers, using Student's f-test for hexenoic acid) is a potent, selective antagonist paired data. at vascular and pulmonary thromboxane A2 When dosed orally to human volunteers ICI (TXA2) receptors in several species (Jessup et 192605 (1 mg) did not significantly (P > 0.05) al., 1988a). When evaluated in human platelet modify ex vivo platelet aggregation induced by rich plasma in vitro, the drug blocks U-46619 either U-46619 or ADP. The drug at higher and collagen induced aggregation and also doses (2, 5, 10, 20, 50 and 100 mg) caused modifies the secondary but not the primary significant (P < 0.05), dose related inhibition phase of adenosine diphosphate (ADP) and of U-46619 induced platelet aggregation, yield- adrenaline responses (Jessup et at., 1988b). The ing peak mean (± s.e. mean) concentration purpose of this study was to determine the ex ratios at 1 h of: 1.77 ± 0.27 (n = 5); 2.64 + vivo platelet activity of ICI 192605 when admin- 0.53 (n = 6); 7.27 ± 2.14 (n = 6); 32.9 ± 21.6 istered as a single oral dose to human volunteers. (n = 6); 35.7 ± 5.6 (n = 6) and 36.1 ± 13.2 (ni = A double-blind randomised study was under- 3) respectively. ICI 192605 (1-100 mg) had no taken in which 17 male volunteers aged 18-36 effect on the primary phase of ADP induced years, body weight 55-88 kg, received ICI aggregation at any time point. The compound 192605 on two occasions and placebo on another; was well tolerated in volunteers. the interval between doses was 7 days. The We conclude that ICI 192605 is a potent, volunteers gave informed consent and the study selective thromboxane receptor antagonist was approved by the Ethics Committee. ICI which is orally active when dosed to man. The 192605 was administered orally as one of seven minimum effective oral dose in human volun- doses (1, 2, 5, 10, 20, 50 and 100 mg) following teers is 0.03 mg kg-'.

Jessup, C. L. et al. (1986). J. Pharm. Phtarmac., 38, Jessup, C. L. et al. (1988b). Br. J. Pharmac., 95 (in 754. press). Jessup, C. L. et al. (1988a). Br. J. Phtarmac., 95 (in press).

Inhibition of tachykinin-induced wheal by histamine and cyclooxygenase products. SP also sodium cromoglycate in human skin produces a wheal by a direct effect. Unlike SP, neurokinin B (NKB) predominantly causes a D. C. CROSSMAN' & R. W. FULLER wheal which, in common with SP, is unaltered 'Division of Vascular Biology, Clinical Research by antihistamines and cyclooxygenase inhibitors Centre, Watford Road, Harrow and Department of (Fuller et at., 1978). To investigate further the Clinical Pharmacology, Royal Postgraduate Medical mechanism of SCG, we have studied the effect School, Ducane Road, London W12 ONN of co-injection of SCG with these two tachy- kinins, as well as with the inflammatory agents, The mechanism of action of sodium cromo- histamine and PGE2 as control. Groups of either glycate (SCG) is uncertain; inhibition of mediator five or six male subjects (25-37 years) took release from mast cells does occur at high doses. part. Only one agent was varied on each day However, other actions, such as the interference and the subjects acted as their own controls. with axon reflexes have been postulated (Bamnes, Intradermal injections (50 idl) were made into 1986). Substance P (SP) activates dermal mast the skin of the back using 27 g needles. The cells, causes flare secondary to the release of flare responses were recorded at 5 mmn and Proceedings of the BPS, 19-21 December 1988 711P wheal responses at 10 min. All areas were re- A submaximal dose of SP (1 pmol) was co- corded by tracing and measured by planimetry. injected with varying concentrations of SCG All substances were diluted with normal saline. (0.05 nmol-0.5 ,umol). Statistically significant Statistical analysis was by repeated measures (P < 0.05) reduction in wheal area was obtained analysis of variance. The wheal and flare re- with SCG above 5 nmol. sponse mean ± s.d. (cm2) for the maximum This study demonstrates a new effect of SCG. concentration of each agent in the presence and The results obtained here are not explained by absence of 0.5 ,umol SCG is shown in Table 1. mast cell inhibition since it is the flare forma- The wheal responses to SP and NKB, but not tion by SP which is mast cell dependent, and histamine, were significantly reduced by the co- the wheal response to both SP and NKB is injection of 0.5 ,umol SCG. This concentration caused directly by stimulation of NK receptors. of SCG had no effect upon the flare response These results raise the possibility that SCG is a to saline SP, NKB, histamine nor PGE2. tachykinin receptor antagonist.

Table 1 Saline SP NKB HIST PGE2 100 pmol I nmol 1 nmol 1 nmol 1.4 nmol Flare -SCG 1.08 ± 0.93 19.70 ± 0.69 1.76 ± 0.6 8.59 ± 5.63 12.47 ± 4.28 +SCG 2.02 ± 1.62 24.00 ± 2.48 2.4 ± 1.21 11.93 ± 5.36 12.95 ± 6.55 Wheal -SCG 0.54 ± 0.12 2.67 ± 0.61 1.43 ± 0.16 0.93 ± 0.24 1.09 ± 0.17 +SCG 0.63 ± 0.14 1.70 ± 0.47 0.98 ± 0.25 0.91 ± 0.19 1.00 ± 0.36

Barnes, P. J. (1986). Lancet, i, 242. Fuller, R. W. et al. (1987). Br. J. Pharmac., 92, 781.

Adverse drug reaction reports in the Royal Liverpool Hospital 1985-1988

L. E. IRVIN, P. A. WINSTANLEY, J. C. SMITH, M. L'E. ORME & A. M. BRECKENRIDGE Royal Liverpool Hospital Pharmacy, and Depart- ment of Pharmacology and Therapeutics, The Uni- versity of Liverpool, Liverpool

Winstanley, P. et al. (1989). Br. J. clin. Pharmac., 28 (in press).

DEMONSTRATIONS

A computerised system for the assessment Micro-computerisation of cognitive assessment of drug-induced performance changes in techniques has introduced a greater degree of young, elderly or demented populations sensitivity to the measurement of drug-induced cognitive performance changes. Further it has P. M. SIMPSON, K. A. WESNES & L. CHRISTMAS enabled standardisation of procedures and test (introduced by G. R. McClelland) administration, whilst increasing the variety of Cognitive Drug Research, Reading, RG1 4RB situations in which testing can be conducted. 712P Proceedings of the BPS, 19-21 December 1988 We have developed such a system and have and also to relate directly to other assessments demonstrated its utility in young, healthy elderly of cognitive functioning in the elderly (e.g. the and demented patients. MMSE and the Kendrick). Versions of the Initially, tests of proven validity and sensitivity system have proven sensitive to the effects of a in assessing cognitive drug effects in young number of compounds in the elderly: in one volunteers were installed on a BBC micro- trial, a cognitive activator was found to improve computer and utilized in various drug trials. performance in elderly volunteers (Wesnes et Tasks were not selected simply due to their al., 1987b), in another study, a novel profile of blanket drug sensitivity but primarily for their acute effects of nortriptyline on cognitive func- ability to provide relatively discrete measures of tioning in the elderly was identified, and in a successive stages of various aspects of cognition third, acute cognitive effects of trazodone and (e.g. attention, information processing, recog- moclobemide were established in one elderly nition memory etc.) in order that a cognitive group receiving alcohol and another group profile of any drug's action could be obtained. receiving placebo-alcohol (Wesnes et al., Sensitivity of the system in this population was 1989). The system is currently being tested in confirmed with the ability to detect both a wide Alzheimer patients by two groups, one looking profile of cognitive impairments induced by at the effects of physostigmine and the other scopolamine (Wesnes et al., 1988) and a number THA, and a major multi-centre trial of a new of antagonisms to these impairments following neotropic in multiple infarct dementia patients the administration of nootropic compounds is about to start. (Wesnes et al., 1987a). Parallel versions of the The test battery has now been installed on an tasks were then prepared for use with elderly IBM compatible, portable, XT microcomputer, volunteers and demented patients. These were with a 40 Mb hard disk drive. This system will demonstrated to have high test-retest reliability, be demonstrated to the Society.

Wesnes, K. et al. (1987a). Med. Sci. Res., 15, 1063. Wesnes, K. et al. (1989). Br. J. clin. Pharmac., 27, Wesnes, K. et al. (1987b). Hum. Psychopharmac., 2, 649P. 159. Wesnes, K. et al. (1988). Hum. Psychopharmac., 3, 27.

A microcomputer based system for the analysis of smooth pursuit eye movements recording and analysis of smooth pursuit and another for analysis of saccades. Stimulus and saccadic eye movements files can be created by the investigator, defining the frequencies, amplitudes and number of A. L. VAN STEVENINCK, A. F. COHEN & cycles for smooth stimuli and the amplitudes, T. WARD1 number of cycles and range for interstimulus Centre for Human Drug Research, University intervals for saccades. The stimuli are D/A con- Hospital, Leiden, The Netherlands and 'Cambridge verted by a CED 1401 interface to 12 bit accuracy Electronic Design, Cambridge, CB4 4FE and displayed on a bar of light emitting diodes (Nihon Kohden (NK) Nystagmo stimulator SLE Computer analysis of smooth pursuit (Bitten- 5100) which allows for both horizontal and court et al., 1982) and saccadic eye movements vertical eye movement registrations. (Baloh et al., 1975) are frequently used in the Eye movements are recorded using disposable assessment of (side) effects of drugs involving 'clip on' silver/silver-chloride electrodes. An the central nervous system. input panel selects the ENG leads to be ampli- The system demonstrated combines record- fied and allows for checking the electrode resist- ing and analysis of both types of eye movements ance. Signals are amplified using a N.K. ENG in a single program. The program runs on a amplifier type AN-601G (DC-2OHz) and A/D 640K AT compatible computer with a mathe- converted at a frequency of 300 Hz by the CED matics co-processor. The program is menu driven 1401 to 12 bit accuracy. Direct display of the and consists of three parts: one for calibration recordings of the computer screen allow for and recording of smooth pursuit and saccadic control on drift and clipping of the signal. The eye movements, one for the analysis of smooth recordings are automatically saved on a 20 Mb pursuit and saccadic eye movements, one for hard disk for subsequent analysis. Proceedings of the BPS, 19-21 December 1988 713P

The program for analysis of smooth pursuit data has the same options for display of results eye movements can display the original stimulus, and for setting of analysis parameters. The pro- raw data, filtered data, differential (velocity) gram identifies the beginning and ending of and differences between stimulus and response. saccades, reaction time, maximum velocity and For each stimulus frequency and for each time to peak velocity. Additionally differences stimulus velocity the percentage of smooth between the stimulus amplitude and the cor- pursuit is calculated by subtracting the total of responding saccade and eventul corrective saccadic episodes, identified in the differential saccades are identified. Results can be saved of the recordings, from the total recording time. in ASCII files. Further tabulation, creation of Analysis parameters can be defined by the graphics and statistical analysis can be per- investigator. The program for analysis of saccadic formed using suitable programs.

Baloh, R. W. et al. (1975). Neurology, 25, 1065. Bittencourt, P. R. M. et al. (1982). Electroencephalo- graphy and clinical Neurophysiology, 54, 399.