PROCEEDINGS OF THE BRITISH PHARMACOLOGICAL SOCIETY CLINICAL PHARMACOLOGY SECTION

9-11 September 1987

UNIVERSITY OF OXFORD

For oral communications with more than one author, an asterisk(*) denotes the one who presented the work. 90P Proceedings of the BPS, 9-11 September 1987 COMMUNICATIONS Low dose angiotensin II enhances proximal min clearance period (CP). Urine was collected tubular sodium reabsorption in man for this and a further CP after the infusion. Absolute Na+ excretion (UNa + V) (,mol J. McMURRAY*, P. H. SEIDELIN & min-' ± s.e. mean) for the baseline preinfusion A. D. STRUTHERS CP, the infusion CP and post infusion recovery Department of Clinical Pharmacology, Ninewells CPwas: (a) 119 ± 15; 112 ± 14; 108 ± 14. (b) 108 Hospital and Medical School, Dundee DD1 9SY + 13; 82 + 10; 101 ± 14 (P < 0.01 vs control). Fractional Na+ excretion (FENa+) (% s.e. The renin-angiotensin-aldosterone system mean) for the equivalent CP was (a) 0.84 ± 0.1; (RAAS) is crucial in the maintenance of Na+ 0.75 ± 0.1; 0.72 ± 0.09 (b) 0.82 ± 0.09; 0.56 + balance in man. The role of aldosterone in Na+ 0.07; 0.69 ± 0.09 (P < 0.02 vs control). Fractional homeostasis is well known (Laragh, 1985). In Li+ excretion (FEL,-) (% + s.e. mean) was: (a) addition, however, there are now animal data to 31 ±2;30+2;34+3. (b)29±2;23±2;27±3. suggest that angiotensin II (All) plays a direct (P < 0.01 vs control). Distal Na+ reabsorption role, independent of aldosterone, in controlling (RDNa+) (% ± s.e. mean) was: (a) 34 ± 2; 34 + renal Na+ reabsorption. For example, studies in 3;38 ± 4.8. (b)28 ± 3;25 ± 3;28 ± 4. (P<0.05 experimental animals suggest that All itself has vs control). Aldosterone levels (pg ml-') were: potent effects of Na+ handling, mainly within (a) 168 ± 26; 189 ± 29; 171 ± 30. (b) 240 ± 36; the proximal tubule (PT). However, the effects 282 ± 47; 293 ± 35 (P < 0.01 vs control). HR and of physiological changes in All have been little BP did not change during either infusion. studied in man and evidence for a tubular site of All was potently antinatriuretic at the low action of All in man is lacking. To investigate dose used in this study. FENa+ also decreased these questions further, we have now studied the indicating a tubular site of action. Li+ is a specific effect of All on renal Na+ and Li' handling in marker for PT Na+ handling (Thomsen, 1984). salt replete normal volunteers. FEL`+ fell during All infusion indicating enhanced Six subjects were studied in the seated position PT Na+ reabsorption. AII also increased aldo- on two separate occasions. At 22.00 h the evening sterone secretion but the fall in RDNa+ suggests before the study each volunteer ingested 500 mg that aldosterone contributed little, if anything to of lithium carbonate. An initial water load of 15 the antinatriuresis caused by All. ml kg-1 of water was given at the start of the These results demonstrate for the first time in study. Urine was voided every 20 miii thereafter man, using Li+ as a specific marker, that physio- and the same volume of water drunk until a logical changes in All increase PT Na+ reabsorp- steady state diuresis was established. Aliquots of tion. This effect of AII may also be significant in urine were kept for later analysis. An infusion of disease states where the RAAS is activated. The either (a) 5%-D-glucose or (b) All 1 ng kg-' removal of the direct PT effect of All may also min-' was then administered for a further 20 be an important action of ACE inhibitors.

Laragh, J. H. (1985). Newv Engl. J. Med., 313, 1330. Thomsen, K. (1984). Neplirotn, 37, 217.

The renal effects ofatrial natriuretic peptide haloperidol or chlorpromazine) has been re- in man are not attenuated by D-sulpiride ported to inhibit or completely block these effects of ANP (Webb et al., 1986; Marin-Grez et al., S. FREESTONE*, T. M. MacDONALD, 1985). This was not confirmed in dogs using SCH R. F. JEFFREY & M. R. LEE 23390 (Murphy et al., 1986). We have therefore University Department of Clinical Pharmacology, The investigated the effect of dopamine receptor Royal Infirmary, Edinburgh, EH3 9YW blockade with D-sulpiride (S) on the effects of ANP in man. Infusion of oa-human atrial natriuretic peptide Eight healthy male volunteers (mean age 31.5 (ANP) causes a marked diuresis and natriuresis. range 24-42 years) were studied on two occasions, In rats, pre-treatment with dopamine (DA&)- at least 7 days apart. They took a normal diet and receptor antagonists (SCH 23390, D-sulpiride, for 2 days before each study day a supplement of Proceedings of the BPS, 9-11 September 1987 91P 100 mmol sodium (10 slow-sodium tablets), but Baseline urine flow rate and natriuresis were fasted on the morning of study. They were given similar on both days (Table 1), as were urine 500 ml of water by mouth and 200 ml every 30 dopamine excretion and blood pressure. D- min thereafter, plus an i.v. infusion of 0.9% sulpiride infusion did not alter these parameters saline (80 ml h-1). After 2 h subjects received D- significantly. Plasma concentrations of ANP sulpiride, a relatively selective DA1 antagonist, during infusion were not significantly different on one of the days (an i.v. bolus of 1.5 mg kg-l on both days (at the midpoint -431 ± 62 pg ml-1 over 5 min followed by an infusion of 1.5 mg kg-1 (ANP only) vs-451 ± 155 pg ml-' (ANP + S)). over 55 min then 1 mg kg-' hourly for 3 h). ANP at this dose level caused no change in blood This has been shown previously to attenuate the pressure or pulse rate. D-sulpiride did not signi- renal effects of the dopamine prodrug gludopa ficantly attenuate the effects of ANP (Table 1). (MacDonald et al., 1987). At 4 h, a 1 h infusion Under the conditions of this study DA1- of ANP 7.5 pmol kg-' min- was commenced. receptor blockade with D-sulpiride did not reduce Urine was collected hourly for 4 h during the run urine flow or natriuresis and did not attenuate in period, but at 30 min intervals during the ANP the renal effects of ANP. We conclude that the infusion. Blood pressure and pulse rate were renal effects of this peptide are not mediated by measured by a Dinamap recorder. dopaminergic (DA1) receptors in man.

Table 1 Mean (s.d.) urine flow rate and natriuresis Baseline (0-2 h) After S (2-4 h) Peak (4.5-5 h) ANP ANP + S ANP ANP + S ANP ANP + S Urine flow rate 8.2 (3.3) 8.2 (3.2) 7.8 (1.7) 8.3 (2.1) 14.8 (3.3) 14.4 (4.8) (ml min-1) Natriuresis 0.29 (0.09) 0.27 (0.11) 0.27 (0.07) 0.28 (0.10) 0.58 (0.19) 0.53 (0.16) (mmol min'-)

MacDonald, T. M. etal. (1987). Br. J. clin. Pharmac., Murphy, M. B. (1986). Clin. Res., 34, 712A. 23, 612P. Webb, R. L. et al. (1986). Life Sci., 38, 2319. Marin-Grez, M. et al. (1985). Life Sci., 36, 2171.

Lithium attenuates the renal response to Seven healthy male volunteers aged 21-39 -y-L-glutamyl-L-dopa in man years were studied on two occasions under water loaded, salt-replete conditions. On each day R. F. JEFFREY*, T. M. MacDONALD & M. R. LEE normal saline (50 ml) was infused during a 90 Department of Clinical Pharmacology, The Royal min baseline period, followed by gludopa (25 ,g Infirmary, Edinburgh EH3 9YW kg-l min-1 in 50 ml normal saline) for 90 min, then a further 90 min recovery period with normal Analysis of the renal clearance of lithium has saline (50 ml). On one occasion, lithium carbonate been claimed to provide a marker for proximal (750 mg, Camcolit) was taken by mouth at 22.00 h tubular sodium reabsorption and the method has the previous evening. Subjects remained supine been used to identify the site of action in the except to void. Blood and urine samples were nephron of natriuretic agents (Thomsen, 1984). taken at 45 min intervals. Dopamine produces a natriuresis by increasing Gludopa alone increased urine dopamine ex- glomerular filtration rate and in addition, in cretion from 1.1 ± 0.1 to 854 ± 56 nmol min-' vitro studies have suggested a proximal tubular (mean ± s.e. mean P < 0.001), raised sodium action (Bello-Reus et al., 1982). -y-L-glutamyl- output from 0.18 ± 0.08 to 0.44 ± 0.08 mmol L-dopa (gludopa) is a highly efficient, renally min-' (P < 0.01), and suppressed plasma renin selective, dopamine prodrug in man (Worth et activity (PRA) from 1.40 ± 0.37 to 0.77 ± 0.15 al., 1985). We have assessed the effect of this ng Al ml-' h-', a 46% reduction (P < 0.05). dipeptide on renal salt handling and lithium Creatinine clearance and plasma atrial natriuretic clearance in man. peptide concentrations (ANP) were not signifi- 92P Proceedings of the BPS, 9-11 September 1987 cantly altered by gludopa. On the morning after not alter baseline dopamine levels or the dopa- lithium was taken, the plasma level was 0.29 + mine output after gludopa. Creatinine clearance 0.04 nmol I` at the start of the baseline period and plasma ANP were not different with lithium. and declined to 0.24 ± 0.04 mmol I` at the end A single dose of lithium, producing sub- of the study. Lithium clearance was unchanged therapeutic plasma levels affects baseline sodium after gludopa (28.4 ± 4.9 to 30.7 ± 4.5 ml min-1 output and PRA. It significantly reduces the NS). Baseline sodium output was significantly natriuretic response to dopamine formed in the increased in the presence of lithium (0.27 ± 0.04 kidney after gludopa, presumably by an inter- vs 0.18 ± 0.08 mmol min-1, P < 0.01). However action at the proximal tubular cell. This study during and after gludopa, the cumulative natri- demonstrates that care must be taken in inter- uresis above baseline was markedly attenuated preting the results of clearance studies which (14.5 ± 8.0 vs 41.8 ± 9.5 mmol, P < 0.01). presume lithium to be pharmacologically inert. Baseline PRA tended to be higher with lithium In addition, the lithium clearance method may (2.38 ± 0.37 vs 1.40 ± 0.37 ng Al ml-' h-, P = not be suitable for investigating dopaminergic 0.066) though the reduction after gludopa was of effects in the kidney. similar magnitude (40%, P < 0.02). Lithium did

Bello-Reus, E. et al. (1982). Am. J. Physiol., 242, Thomsen, K. (1984). Nephron, 37, 217. F634-640. Worth, D. P. et al. (1985). Clin. Sci., 69, 207.

A comparison ofthe renal effects ofibuprofen electrolyte excretion, inulin clearance (CIN) and and indomethacin in subjects with moderate p-aminohippurate clearance (CPAH). F effects salt restriction with P were analysed using multiple t-tests with significance adjusted using Sidak's formula. The A. P. PASSMORE* & G. D. JOHNSTON profile after F (using orthogonal polynomial Department of Therapeutics and Pharmacology, The decomposition) and differences between treat- Queen's University of Belfast, 97 Lisburn Road, ments were compared using repeated measures Belfast BT9 7BL, Northern Ireland of analysis of variance with Neumann-Keuls multiple comparisons. We have previously reported on the renal effects Neither NSAID affected CCR, Na+ or K+ of ibuprofen (IBU) and indomethacin (IND) in output. PRA was suppressed by IND (0.9 ± 0.2) healthy volunteers on 150 mmol I1 Na+ intake/ ng Al ml-' h-1, P < 0.01) compared with P (2.2 day (Passmore & Johnston, 1987). An intact ± 0.5) but PRA values on IBU 400 (1.3 ± 0.3) renal prostaglandin system is considered more and IBU 800 (1.7 ± 0.5) were not different from important for renal function in conditions of P or IND. Control values before F were un- sodium depletion. To compare the renal responses affected by NSAIDs. With P following F, Na+/ to IBU and IND in this setting, eight healthy K+ output and urine volume were significantly male volunteers on a 60 mmol Na+/60 mmol K+ increased at each time period (P < 0.01), while diet were randomly allocated as part of a double- CIN (A = 48 ± 9 ml min and CPAH (A = 227 blind, cross-over design, IBU 400 mg three times ± 39 ml min-', P < 0.01) increased only at the daily, IBU 800 mg three times daily, IND 50 mg first time period. The urine flow rate profile three times daily and matching placebo (P) for 3 after F was lower with IBU 400 (P < 0.05), IBU days. Creatinine clearance (CCR) and 24 h Na+/ 800 (P < 0.01), IND (P < 0.01) with no differ- K+ output were measured on day 3 of each ences between NSAIDs. Na+/K+ excretion pro- treatment period. On day 4 plasma renin activity files after F were not significantly altered by (PRA) was estimated over a 30 min period of NSAIDs. PRA was reduced by IBU 400 (P < supine rest, the final treatment given, and an 0.01), IBU 800 (P < 0.01) and IND (P < 0.01) at inulin and p-aminohippurate infusion com- 10, 30, 50 min after F, with no differences be- menced. Subjects received 450 ml water followed tween NSAID treatments at any time point. by 150 ml every 30 min. After 2 h a 1 h urine IND significantly reduced CIN and CPAH re- collection was obtained, a blood sample taken sponses to F (P < 0.05). CIN following F was for PRA and 20 mg frusemide (F) given i.v. For significantly reduced by IBU 400 (P < 0.05). 3 x 20 min periods urine was collected and blood Neither dose of IBU affected the CPAH response sampled at intervals for PRA, urinary volume, to F. IBU doses were not different from IND Proceedings of the BPS, 9-11 September 1987 93P except for IBU 400 which had less suppressant 400 reduced CIN after frusemide. Unlike the effect than IND on CPAH. Neither NSAID previous study in salt replete volunteers, indo- affected basal water, Na+/K+ excretion or renal methacin significantly attenuated the renal hae- haemodynamics and there were no differences modynamic responses to frusemide in conditions between the two doses of IBU except that IBU of moderate salt depletion.

Table 1 Pre F F +JO min F + 30 min F +SO min CPAHt CINt CPAH CIN CPAH CIN CPAH CIN P 570 ± 45 87 ± 9 797 ± 76 135 ± 12 622 ± 43 99 ± 9 596 ± 53 75 ± 4 IBU 400 573 ± 39 97 ± 6 739 ± 55 119 ± 5* 516 ± 33 78 ± 6* 517 ± 54 85 ± 3* IBU 800 527 ± 41 90 ± 9 657 ± 37 114 ± 4 590 ± 38 105 ± 11 630 ± 51 97 ± 10 IND 522±54 79±7 544±60*t 80± 11* 444±30*t 63 ± 5* 517±49*t 67 ± 6* t ml min-' 1.73 m-2; *P < 0.05 compared with P; tP < 0.05 compared with IBU 400 mg Passmore, A. P. & Johnston, G. D. (1987). Br. J. clin. Pharmac., 23, 611P.

Tenoxicam: effect on renal function in 0-8 h. Renal plasma flow (RPF) was measured normal man from the 0-1 h renal clearance of PAH after a single i.v. injection (McAuslane etal., 1987). All J. A. N. McAUSLANE*, S. FREESTONE, subjects were hydrated to ensure adequate urine J. COWIE & L. F. PRESCOTT flow. Urinary electrolyte and urinary enzyme University Department of Clinical Pharmacology and (N-acetyl-glucosaminidase (NAG) and 32- Medical Renal Unit, The Royal Infirmary, Edinburgh microglobulin) excretion were also measured. EH3 9YW The latter are markers ofproximal tubule damage. Inulin and creatinine were measured by spectro- Tenoxicam (T), a thienothiazine derivative of photometric autoanalyser methods and PAH by the oxicam class, is a new long acting non-steroidal h.p.l.c. anti-inflammatory drug (NSAID). There is Inulin, creatinine and PAH clearances did not clinical evidence linking NSAID with adverse change significantly in either group (Table 1). effects on renal function, probably mediated via There were no significant differences in 24 h the inhibition of prostaglandin synthesis. urine volumes or sodium and potassium excre- We have examined the effects of tenoxicam on tion. Urinary NAG excretion did not increase in the renal function of 16 healthy male subjects the tenoxicam group (baseline 112.5 ± s.d. 77 vs (mean age 27 years, range 22-42 years) over a day 10113.3 ± 77 units mg-' creatinine, NS) and period of 10 days in a randomised, double-blind, 132-microglobulin excretion remained normal placebo-conrtrolled, parallel group study. Sub- (< 300 ,ug ml-l). jects received two tablets (T 40 mg or placebo) Under the conditions of this study, tenoxicam on days 1 and 2, followed by one tablet (T 20 mg did not appear to cause an important decline in or placebo) for the next 8 days (n = 8 in each the renal function of healthy subjects. Further group). Renal function was evaluated on a base- studies should be performed in patients with line day (B) and on days 3 arid 10 of dosing. renal impairment and other at-risk groups. Glomerular filtration rate (GFR) was-estimated from the 0-2 h total body clearance of inulin after J. A. N. McAuslane is supported by Roche Products a single i.v. injection (Freestone et al., 1986) and Ltd. creatinine clearance was also measured from 94P Proceedings of the BPS, 9-11 September 1987

Table 1 Mean (s.d.) clearances of inulin, creatinine and PAH (ml min-' 1.73 m-2) Parameter Placebo Tenoxicam Day Day Baseline 3 10 Baseline 3 10 GFR 107 (10) 104 (10) 105 (13) 108 (13) 107 (14) 106 (14) Creatinine clearance 114 (5) 118 (15) 123 (22) 120 (14) 119 (17) 119 (10) RPF 591(115) 608 (130) 577 (135) 552 (70) 554 (132) 563 (108)

Freestone, S. et al. (1986). Br. J. clin. Pharmac., 21, McAuslane, J. A. N. etal. (1987). Br. J. clin. Pharmac., 97P. 24, 277P.

Adverse drug reactions in elderly patients in (8% of all E patients) there was no record of hospital whether an ADR history had been taken and of these 25% developed an ADR. The correspond- N. D. S. BAX*, R. K. RICHARDS', H. S. WOODS, ing values for Y patients were 17% (42), 32% H. F. WOODS & D. E. BAX (28) and 30 (8% of all Y patients) respectively University Department of Pharmacology and Thera- with 33% of the latter group developing an ADR. peutics, Royal Hallamshire Hospital, Sheffield SlO In the 684 E patients, the presence or absence 2JF and 'Computing Services, University of Sheffield, of a history of atopic disease was recorded in 274 S3 7RF (40%). ADR incidence was 5/25 (20%) in those with atopy and 46/249 (18%) in those without Drug therapy and adverse reactions (ADRs: atopy, contrasting with 17/44 (39%) and 14/94 events that were unwanted effects of therapy) (15%) respectively in Y patients for whom the were monitored in all patients (1042) admitted history was recorded. to a general medical ward over 2 years. Young The incidence of ADRs did not increase with (Y) patients (< 65 years) accounted for 34% and age (age: % of patients with ADR; 25-34: 31; elderly (E) patients (> 65 years) accounted for 35-44: 14; 45-54: 26; 55-64: 20; 65-74: 24; 75- 66% of admissions. No self-poisoning cases 84: 22; 85-94: (20). Drug therapy was changed were admitted. Events judged to be ADRs were following 70% of the ADRs in E patients. After identified and recorded prospectively. The rela- 4% of the ADRs it was uncertain from the notes tionship of these events to drug therapy was whether any alteration in therapy had been made. examined retrospectively. Comparison of Y:E patients suggested that in- A total of 336 ADRs were noted, 227 occurring appropriate drugs and incorrect dosages had in 155 E patients, 109 in 79Y patients. Defining a been used in 9%:4% and 10%:13% of ADRs treatment as one dosage of one drug the % of respectively. treatments resulting in ADRs in the Y and E was Some drugs with above average incidences of 3% in both groups. The risk of developing an ADRs (ADR frequency as % of total number of ADR was directly related to the length of hospital treatments, Y:E) were-atenolol 6:13, Magna- stay for both Y and E patients (stay in days; % of pen 0:12; digoxin, 5:5; prednisolone, 8:5; pheny- E, Y with ADR; 0-10: 14, 17; 11-20: 22, 28: 21- toin, 24:9; penicillin, 23:6. 30: 33, 30; 31-40: 46, 48; 41-50: 55, 50; 51-100: Compared with Y patients, the elderly did not 52, 66). seem especially prone to ADRs. Improved clinical ADRs were noted in 19% of those E patients history taking and record keeping might lessen with no history of a previous ADR (94) and in the risk of causing an ADR. 33% of those with a previous ADR (48). For 55 Proceedings of the BPS, 9-11 September 1987 95P

Genetic and environmental influences on and the quantity of SA excreted was given by the salicylate metabolism expression a.xb where x is urine pH, a = 2.613 x 10-5 and b = 7.14. Values for SA excretion were K. S. FORDYCE*t, L. J. NOTARIANNI & corrected to that for the mean urine pH of 6.2 for P. N. BENNETT all subsequent calculations (Whittaker & Price- School of Pharmacy and Pharmacology, University of Evans, 1970). Bath and Clinical Pharmacology Unit, Royal United Gender affected salicylate metabolism, for Hospital, Bath males excreted as SUA 213.6 ± 5.0 and females 163.1 ± 8.7 mg (P < 0.01) but there were no Phase I drug metabolic reactions have been differences between smokers and non-smokers much studied but Phase II reactions less so, or, among females, users and non-users of the yet the latter are important as they generally oral contraceptive pill. There was no correlation terminate drug activity. The principal route of between age or body weight and SA and SUA salicylic acid (SA) metabolism is conjugation excretion. A frequency distribution histogram of with glycine to form salicyluric acid (SUA) and SA/SUA was strongly positively skewed and the this shows large interindividual differences. We probit plot was non-linear (X2 = 44.1, P < 0.01). have used SA conjugation with glycine to in- The study was repeated in 13 volunteers after vestigate influences on a Phase II reaction. 7-27 months: SUA excretion was largely repro- One hundred and fifty healthy volunteers (88 ducible but corrected SA excretion and SA/SUA male: 33.3 ± 1.5 (s.e. mean) years, 72.9 ± 1.0 kg showed variations of 25-400% and 25-500% and 62 female: 26.9 ± 1.4 years, 60.4 ± 1.2 kg) respectively in 85% of the subjects. took aspirin 600 mg by mouth and collected all Genetic control may be partially responsible urine passed for 8 h. SA and SUA were assayed for the skewed distribution of SA conjugation by h.p.l.c. and amounted to 3.3 ± 0.2% and 42.0 but environmental factors must also underlie the + 1.1% of the dose respectively. SA excretion deviation from a normal distribution. correlated with urine pH (r = 0.732, P < 0.001)

Whittaker, J. A. & Price-Evans, D. A. (1970). Br. med. J., 4, 323. tPresent address: Hazleton Laboratories, Harrogate, Yorks

Circadian variation in theophylline absorp- studying 24 h concentration-time profiles and to tion during chronic dosing with a slow release identify the effect of changing the clock times of preparation dosing. Eight volunteers, aged 25-45 years, were each S. H. D. JACKSON*, A. JOHNSTON & given 200 mg of slow release theophylline by R. C. WOOLLARD mouth 12 hourly: four volunteers were dosed at Department of Clincial Pharmacology, St Bartholo- 11.00 h and 23.00 h (regimen 1) and four at 17.00 h mew's Hospital, London EClA 7BE and 05.00 h (regimen 2). Hourly sampling was carried out from the time of the 6th dose. After We and others have previously demonstrated at least a week each subject crossed over to the higher predose serum theophylline concentra- other dosing regimen and a second 24 h profile tions in the morning vs evening during chronic 12 was obtained. Serum samples were analysed hourly dosing with slow release theophylline using an enzyme mediated immunoassay with a (Jackson et al., 1984). We have also demon- coefficient of variation at 5.4 mg 1-1 of < 5%. strated the abolition of this circadian variation The most striking difference in the pharmaco- by changing the clock time of dosing. Most in- kinetic parameters for the four dosing times was vestigators have demonstrated no change in total an increase in tmax from 3.3 ± 1.7 h (mean ± and non renal elimination rate constant at night. s.d.) after dosing at 11.00 h to 9.3 ± 1.8 h after The objectives of this study were to identify dosing at 23.00 h (P < 0.001). During regimen circadian differences in the absorption of a slow 2 tmax values were intermediate between those release theophylline preparation (Uniphyllin of regimen 1 (6.4 and 5.3 h). Mean AUC (0-12) Unicontin) during chronic 12 hourly dosing by after dosing at 11.00 h was 89.9 ± 29.0 mg 1-1 h vs 96P Proceedings of the BPS, 9-11 September 1987 79.0 ± 25.0 mg I1- h after dosing at 23.00 h (P < due to a marked delay in absorption after evening 0.005). Again during regimen 2 there was little dosing. This circadian effect can be abolished by difference (85.4 vs 84.8 mg 1-1 h). Mean AUC dosing at 17.00 h and 05.00 h. The mechanism of (0-24) values during the two regimens were the effect may be a reduction in the rate of almost identical. Cmax values after all dosing gastric emptying induced by the supine posture, times were similar. sleep itself or an endogenous circadian rhythm Thus, the previously well documented higher or a combination. The timing of meals cannot predose concentrations in the morning com- explain the results. pared with the evening, at least in large part, are

Jackson, S. H. D. et al. (1984). Br. J. clin. Pharmac., 17, 777.

Evaluation of steady state plasma levels of teers although this was either not significant (day nicardipine hydrochloride in patients with 1) or of borderline significance (day 8). The impaired liver function mean AUC (area under the curve) values were 4.9 fold and 4.0 fold higher in patients as com- F. D'HEYGERE*, T. LING1, G. WADDELL, pared with volunteers on days 1 and 8 respectively B. HARLOW2, I. JAMES & N. McINTYRE (P < 0.05). The ratio of AUCs (day 8/day 1) was Medical Department, The Royal Free Hospital, not significantly different between patients (1.23) London, NW3 2QG, 'Syntex Research, Palo Alto, and volunteers (1.59), neither was the time to California and 2Syntex Clinical Research-Europe, peak concentration (0.76 h for patients and 0.89 h Maidenhead, Berkshire SL6 1RD for volunteers). At steady state the apparent oral clearance in To determine the pharmacokinetics and safety patients (18 ml min-' kg-l: was one-fifth of that of nicardipine (NIC), 20 mg of NIC twice daily in volunteers (82 ml min- kg-1). The AUC of was given for a week to 11 patients with impaired the pyridine metabolite of NIC(M5) was only 1.6 liver function (10 male, average age 45 years) fold higher in patients and the ratio of AUCs and to six volunteers (five male, average age (M5/NIC) was lower in patients (0.29) compared 40 years). All patients had hepatic cirrhosis asso- with volunteers (0.62). This suggests that NIC is ciated with abnormal but stable liver function. metabolised to M5 to a smaller extent in patients, Patients and volunteers received 20 mg oral thus contributing to a lower clearance compared NIC on days 1 and 8, and twice daily 20 mg on with volunteers. There was a nearly two-fold days 2 to 7. Blood pressure and heart rate were increase in the apjarent volume of distribution monitored and serial blood samples were obtained of NIC (12 1 kg- in volunteers, 23 1 kg-' in for NIC plasma levels during the study. Labora- patients). There were no major changes in NIC tory tests were performed at screening and at the protein binding (1.70% unbound in volunteers, end of the study. Adverse effects were recorded 1.94% unbound in patients). The increased daily. volume of distribution appears to be due to an On comparing blood pressures and heart rates increase in total body water in cirrhotics. The in both patients and volunteers, there was only a terminal plasma half-life of NIC was prolonged diastolic hypotensive effect in patients which 6.5 fold in patients as compared with volunteers was more marked in the erect position. The side (19.4 h vs 3 h) and appeared to be related to a effects which occurred were those expected for a reduced total systemic clearance and an increased peripheral vasodilator and were similar in the volume of distribution. two groups. The low clearance in cirrhotics implies the Significantly higher plasma concentrations of need to decrease nicardipine dosage in patients NIC were shown in the cirrhotic patients than in with impaired liver function. A 20 mg twice daily the volunteers following acute and steady state regime was shown to be well tolerated, apart dosing. The mean Cm. (peak concentration) from the two patients who redeveloped ascites values were 85% higher in patients than in volun- after their previous therapy had been withdrawn. Proceedings of the BPS, 9-11 September 1987 97P Pharmacokinetic properties of a new & Wing, 1970; Sodermark et al., 1975). extended release quinidine product In the first mutliple dose study, QER and QDUR were given every 12 h to 12 healthy G. NYBERG*, C. JANSSON, U. E. JONSSON, volunteers in a randomized cross-over design. M. SINDEBY CULLBERG In the second study, with otherwise identical AB Hassle, S-431 83 Molndal, Sweden design, QER was administered every 24 h to eight healthy volunteers. The daily doses were Quinidine is a widely used antiarrhythmic drug, 800 mg (corresp. quin.sulph.) in both studies. characterized by a short elimination half-life and Plasma samples were drawn on the fourth treat- a narrow therapeutic range. In order to combine ment day and analyzed for quinidine by means of a convenient dosage regimen with effective a specific h.p.l.c. method. and safe plasma levels, a new extended-release Table 1 shows the pharmacokinetic variables product ofquinidine sulphate has been developed, derived from the two studies. QER had a lower quinidine ER (QER). It is a capsule, containing absorption rate, resulting in minimal fluctuations a large amount of individually coated pellets, in in plasma concentrations during a dosage interval the amounts of 200, 300 or 400 mg quinidine when given twice daily. After once daily admin- sulphate. The drug substance is released during istration of QER the fluctuations were similar to a period of approximately 24 h in vitro. The those of QDUR given twice daily. The extent objectives of our studies were to compare the of bioavailability was equivalent for QER and plasma concentration-time profiles and the ex- QDUR. tent of bioavailability of QER, given every 12 h Based on these results a choice between the and 24 h, with a reference product, quinidine convenient once daily regimen and a twice daily Durules® (QDUR), given every 12 h. QDUR is dosing, producing very small fluctuations in an extended release matrix tablet with well estab- plasma levels, is feasible with quinidine ER. lished clinical efficacy and safety (Byrne-Quinn

Table 1 Mean (s.e. mean) of individual pharmacokinetic variables Study 1 Study 2 QER QDUR QER QDUR tmax (h) 5.3 (0.6) 2.9(0.3) 7.6 (0.3) 3.7(0.3) Cmax (pmol l') 3.8 (0.3) 4.7 (0.4) 5.3 (0.2) 4.9 (0.6) Cmin (IJmol 1l') 2.7 (0.3) 1.9 (0.2) 1.8 (0.2) 2.3 (0.3) Cmax/Cmin 1.6 (0.1) 2.5 (0.2) 3.1 (0.2) 2.2 (0.2) Fre, 0.96 (0.05) () 1.03 (0.06) ()

Byrne-Quinn, E. & Wing, A. J. (1970). Br. Heart J., Sodermark, T. et al. (1975). Br. Heart J., 37, 486. 32, 370.

Influence of time of dosing on the pharma- appearance of verapamil in the plasma, a later cokinetics and pharmacodynamics of tmax and a reduced peak/trough ratio (Hla et al., sustained release verapamil 1987). In patients receiving 1 or 2 240 mg sus- tained release tablets daily, ambulatory blood J. A. HENRY*, K. K. HLA, G. VOLANS, pressure measurements have demonstrated that A. N. LATHAM' & R. BHAMRA the antihypertensive effect was maintained National Poisons Unit, New Cross Hospital, London throughout dosage intervals of 12 or 24 h SE14 5ER and 'Knoll Ltd, The Brow, Burgess Hill (McCormack et al., 1987). RH15 9NE Eight hypertensive patients (3M/5F) aged 42 to 63 years, of normal weights for their heights, Sustained release verapamil (Securon® SR) who had been receiving verapamil regularly provides similar verapamil bioavailability to were studied. Four patients received a single the conventional formulation but with delayed 240 mg tablet of sustained release verapamil 98P Proceedings ofthe BPS, 9-11 September 1987 daily in the morning and four received a single This study has demonstrated a diurnal variation tablet in the evening for 4 weeks. They were then in the pharmacokinetics of verapamil following crossed-over to the alternative regime for a further chronic administration of a sustained release 4 weeks. At the end of each 4 week period dosage form (Table 1). In the small sample patients were admitted for pharmacokinetic and investigated this did not appear to be accom- blood pressure assessments during a 24 h period. panied by differences in blood pressure, which No food was allowed for at least 2 h before and was controlled during the 24 h dosage interval 1 h after dosing and tablets were taken under after either morning or evening dosing. It is supervision. possible that the lower night time bioavailability There were no apparent differences between of verapamil could be advantageous in terms of morning and evening blood pressures at any of reducing adverse effects or during twice daily the time points (Table 2). dosing.

Table 1 The effect of time of dosing on median sustained release verapamil pharmacokinetic variables Time of dose Morning (08.00 h) Evening (20.00 h) A P* tmax (h) 5 12 -6.5 ~0.06 Cmax(ng ml-') 141 83 45.8 < 0.01 Cmin (ng mlP) 56 44 8.3 > 0.1 Cmax/Cmin 3.9 3.1 0.8 > 0.1 C 12 h (ng ml-') 62 66 -5.8 > 0.1 AUC -24 h (ng ml-' h) 1786 1444 -521 < 0.05 *Wilcoxon Matched Pairs Signed Ranks Test

Table 2 Mean ± s.d. supine blood pressures following morning and evening doses Time after dosing (h) 0 3 9 12 21 24 SBP (mm Hg) Morning 146 ± 13 136 ± 19 132 ± 17 141 ± 19 132 ± 17 140 ± 17 Evening 157 ± 22 148 ± 25 133 ± 19 134 ± 19 138 ± 20 140 ± 17 DBP (mm Hg) Morning 94±5 84±8 79±6 84±9 79±5 85±8 Evening 92± 11 87±9 78±8 82±7 86±9 87±7

Hla, K. K. etal. (1987). Br. J. clin. Pharmac., 24, 661. McCormack, P. (1987). Irish J. med. Sci. (in press).

The effects ofverapamil and propranolol on quality of life in hypertension trial of verapamil 120-240 mg twice daily against propranolol 80-160 mg twice daily in 94 patients C. M. A. HAWKINS*, A. E. FLETCHER, with mild-to-moderate hypertension in an inner C. J. BULPITT & L. A. PIKE1 (introduced by city general practice. A. N. Latham) Nineteen per cent of the verapamil group and London School of Hygiene and Tropical Medicine, 28% of the propranolol group withdrew before London, WC1E 7HT and 'Birchfield Medical Centre, the end of the double-blind period (P = 0.12). Birmingham B19 1LH Five patients on verapamil withdrew due to symptom side-effects and seven on propranolol. An assessment of quality of life and antihyper- From spontaneous reporting of complaints, the tensive efficacy was made in a 4-month, double- most common side-effect with verapamil was blind, randomised controlled parallel-groups constipation and with propranolol dizziness. Proceedings of the BPS, 9-11 September 1987 99P A self-administered questionnaire was used to subscales. Total psychiatric morbidity increased measure the quality of life on treatment. The with propranolol by 13% (95% CI -5% to average rate ofreporting symptoms at the end of +31%); anxiety increased by 27% and depression the placebo run-in period was 31% in the vera- by 13%. These within-group changes did not pamil group and 28% in the propranolol group. achieve statistical significance but the total scores These rates dropped to 30% for patients on tended to improve more with verapamil (P = verapamil but rose to 35% for patients on pro- 0.07). pranolol (P = 0.03, between-drug comparison). After 6 weeks the diastolic blood pressure A health status index (Sanshel & Bush, 1970), averaged 86.7 mm Hg with verapamil and 87.6 based on activity and perceived health, improved mm Hg with propranolol. After 4 months the by 2% for patients on verapamil but was 4% averages were 86.2 and 90.3 mm Hg, respectively worse for patients on propranolol (P = 0.01). (P < 0.05). Although it is possible that a greater A total psychiatric morbidity score was derived fall in pressure improves the quality-of-life from the Symptom Rating Test (Kellner & Shef- measurements, the data otherwise suggest that field, 1973). It improved with verapamil by 14% health-related wellbeing is higher with verapamil (95% CI -35% to +7%), with improvements of than with propranolol. 8% on both anxiety and depression in these

Kellner, R. & Sheffield, B. F. (1973). Psychol. Med., Sanshel, S. & Bush, J. W. (1970). Oper. Res., 18, 3, 88. 1021.

Quality of life assessment in patients (25 male, 25 female, median age 31 years) to with angina using the sickness impact determine the impact of angina on quality of life profile (SIP) and to assess the association between dysfunction and clinical measures. Patient Rated Health M. S. SHAYEGAN-SALEK*l, D. K. LUSCOMBE1, (PRH) and the Doctor Rated Health (DRH) S. R. WALKER1, S. PUGH2 & was also assessed. Patients without a working M. J. VANDENBURG2 knowledge of written English were excluded. Centre for Medicines Research, Carshalton, Surrey Scores in all areas were higher for patients and 2Romford Cardiovascular Research, Department than controls (Table 1). Work scored the highest of Cardiology, Oldchurch Hospital, Romford, Essex (34% were retired or unemployed due to angina). Lower scores suggest that other areas are less Angina pectoris has a great impact on physical affected by angina. PRH correlated well with SIP. and psychological capacities. Quality of life Overall SIP and the physical and psychosocial improvement is considered to be an important categories correlated extremely well (P < 0.001) aim of therapy. This is difficult to assess as no with patient rated health. Additionally, overall global measure of dysfunction has been validated SIP scores showed significant (P < 0.001) dif- for use with angina patients. Health status ques- ferences between categories of PRH, especially tionnaires can quantify the impact of sickness on in ambulation, social, sleep, mobility (Ps < the quality of life. The SIP is a self-administered 0.001), home, recreation and alertness (Ps < questionnaire of 136 health related statements, 0.05). There was no correlation between DRH covering 12 areas in three dimensions; physical and SIP despite PRH correlationship with SIP. (movement, mobility, ambulation and body care), In this study, SIP identifies problem areas psychosocial (emotional, social, alertness and in angina pectoris. These findings relate more communication) and independent areas (sleep closely with patient rated health than the doctors' and rest, home, work, recreation and eating). judgment of health and disease. SIP judgements SIP scores in 50 consecutive angina clinic patients may be useful clinically and help assess the effect (41 male, nine female, median age 58 years) of treatment on quality of life. were compared with those of 50 healthy controls lOOP Proceedings of the BPS, 9-11 September 1987 Table 1 Percentage impairment in angina patient and controls using SIP (mean (s.d.)) Category of dimension Number ofitems Patients Controls Overall 136 8.2 (7.4) 0.57 (1.65) Physical dimension 45 5.0 (6.4) 0.37 (1.70) Psychosocial dimension 48 7.6 (9.5) 0.50 (2.10) Sleep and rest 7 13.2 (14.9) 0.25 (1.73) Home management 10 10.3 (15.2) 1.05 (6.35) Work 9 27.1(32.6) 0.65 (2.60) Recreation and pastimes 8 14.0 (16.0) 1.00 (3.61) Eating 9 3.6 (5.1) 0.00 (0.00)

Double-blind evaluation ofsustained release group and 90% of patients in the propranolol verapamil and long acting propranolol in group were classified as responders (P > 0.1) hypertensive patients with 78%, 11% and 4% of verapamil patients responding to 240 mg once daily, 240 mg morning J. A. BOCHSLER*l, R. SIMMONS2, P. J. WARD3, + 120 mg evening and 240 mg morning and P. CHESTER4 & A. N. LATHAM4 evening respectively compared with 73%, 10% 'The Surgery, 13 Gipsy Hill, London, SE19, 2The and 6% of propranolol patients responding to Surgery, 40 Parkhill Road, Bexley DA5 1HU, 3Liver- 160 mg, 240 mg and 320 mg propranolol in the pool Road Health Centre, Luton, LUl 1HH and morning respectively. 4Knoll Ltd, Burgess Hill RH15 9NE Within treatment groups there were highly significant reductions in SBP and DBP relative Sustained release verapamil (Securon® SR) to baseline (Table 1). No significant differences and long acting propranolol (Inderal® LA) are in efficacy were found between treatments. There both indicated for Step 1 pharmacotherapy of was a highly statistically significant reduction in mild to moderate essential hypertension. In this heart rate in the propranolol treatment group (P double-blind parallel group study in general < 0.001) and no significant change in the vera- practice, antihypertensive efficacy, toleration pamil treatment group (P > 0.1). Between treat- and safety of Securon SR and Inderal LA were ment groups the difference in heart rate was determined at the end of a 3 week placebo highly significant (P < 0.001). Two verapamil period (baseline) and at monthly intervals during and nine propranolol patients were withdrawn 4 months of active treatment. Drugs were titrated because of possible drug-related side-effects (P until target blood pressure (sitting diastolic blood < 0.05). Including withdrawals 39% of the vera- pressure < 90 mm Hg or reduction of 15 mm Hg pamil group and 41% of the propranolol group from baseline) was achieved or side-effects reported side effects (P > 0.1), the most common intervened. Blood pressure was measured at being constipation in the verapamil group and routine clinic times using the Hawksley Random tiredness in the propranolol group. No clinically Zero Sphygmomanometer. Daily doses con- relevant abnormal laboratory findings occurred tained 240-480 mg verapamil or 160-320 mg in either group. propranolol with a three step titration option for Both Securon SR and Inderal LA were safe each treatment. and efficacious in the majority of patients suffer- Ninety seven patients (46 verapamil and 51 ing from mild to moderate essential hypertension. propranolol) were enrolled. There were no However, in the Securon SR treatment group significant between group differences in demo- side-effects resulted in significantly fewer with- graphy. Overall 93% ofpatients in the verapamil drawals. Proceedings of the BPS, 9-11 September 1987 lolp

Table 1 Mean ± s.d. systolic and diastolic blood pressure (SBP, DPB 1 mm Hg) and heart rate (HR, beats min-1) Months Baseline 1 2 3 4 Securon SR SBP 166 ± 15 153 ± 13* 148 ± 13* 150 ± 13* 148 ± 12* DBP 102 ± 4 90 ± 6* 86 ± 7* 86 ± 5* 86 ± 7* HR 76 ± 9 77 ± 9 76 ± 8 77 ± 7 76 ± 8 n 46 46 45 44 43 Inderal LA SBP 165 ± 17 148 ± 18* 146 ± 19* 146 ± 14* 143 ± 16* DBP 102 ± 5 90 ± 8* 88 ± 9* 87 ± 5* 86 ± 6* HR 81 ± 10 69 ± 9* 70 ± 9* 69 ± 9* 70 ± 9* n 51 51 46 41 39 *P < 0.001 (within group relative to baseline)

Effects of digoxin, verapamil and diltiazem diltiazem 120 mg, digoxin 0.25 mg + diltiazem upon heart rate, exercise tolerance and 120 mg, verapamil 80 mg, or placebo. Each drug cardiac output in atrial fibrillation was disguised in an identical capsule and the treatments were administered in a randomised, R. LEWIS*, N. IRVINE & D. G. McDEVIIT double-blind manner. Cardiac output was Department of Pharmacology and Clinical Pharma- measured non-invasively using an acetylene re- cology, Ninewells Hospital and Medical School, breathing method (Irvine et al., 1983) both at Dundee DD1 9SY rest, and after patients had exercised to their limits of tolerance on a treadmill according to a Digoxin is still widely used in the treatment of modified Bruce protocol. atrial fibrillation (AF) although it fails to control There was no relationship between post- exercise induced tachycardia (Beasley et al., exercise heart rate and either exercise tolerance 1985). Verapamil (Lewis et al., 1987a) and or cardiac output. The rapid ventricular rates diltiazem (Lewis et al., 1987b) achieve a greater seen after treatment with placebo were not asso- reduction in the ventricular rate but fail to improve ciated with impaired exercise tolerance. The exercise tolerance compared with digoxin. This combination of digoxin plus diltiazem consis- may be because any improvement in cardiac tently achieved the greatest reduction in post- output brought about by prolongation of ventri- exercise heart rates but was not associated with cular diastolic filling time could be outweighed improved exercise tolerance or cardiac output. by the negative inotropism of the calcium an- Cardiac output was highest after treatment with tagonists. We have therefore examined the digoxin, despite rapid ventricular rates. Stroke relationships between heart rate, exercise volume was inversely related to the ventricular tolerance and cardiac output after single doses of rate (rs = 0.37, P < 0.05). digoxin, diltiazem and verapamil in patients with Rapid ventricular response rates do not appear chronic AF. to limit exercise tolerance or cardiac output in Six patients (mean age 64, range 58-72 years; patients with AF. The marked reduction in one female) with chronic AF were studied on six ventricular rates seen with combinations of occasions, each separated by 7-14 days. Digoxin digoxin and diltiazem was not associated with was discontinued 48 h before each visit, and 3 h improvements in either exercise tolerance or before the visit patients took one of the following cardiac output. treatments: digoxin 0.25 mg, diltiazem 60 mg, 102P Proceedings of the BPS, 9-11 September 1987 Table 1 The results of the study Resting Post-exercise HR Cardiac output HR Cardiac output Walking disatnce (beats min-) (I min-') (beats min-') (I min-) (m) Placebo 101.4 5.5 167 9.0 362 Digoxin 97.4 5.8 159 12.6 351 Verapamil 80 mg 79.2 5.5 146 9.5 328 Diltiazem 60 mg 82.3 5.9 143 10.9 379 Diltiazem 120 mg 68.0 5.7 133 9.1 357 Digoxin + diltiazem 68.3 4.9 122 9.1 357 P (ANOVA) < 0.01 NS < 0.01 NS NS

Beasley, R. et al. (1985). Br. med. J., 290, 9. Lewis, R. et al. (1987a). Eur. Heart J. (in press). Irvine, N. et al. (1983). Res. Comm. Chem. Path. Lewis, R. et al. (1987b). Br. J. clin. Pharmac., 24, Pharm., 42, 311. 262P.

Effect of acipimox on plasma digoxin levels or plasma urea and electrolytes before and after in elderly patient volunteers the study. The mean digoxin concentrations on days 0, 1 and 8 are plotted in Figure 1. These P. C. CHIJIOKE*, R. M. PEARSON, were fitted to an oral dosing two compartment A. JOHNSTON & A. BLACKETT pharmacokinetic model (Johnston & Woollard, Department of Clinical Pharmacology, St Bartholo- 1983). The mean area under the curve (time 0 to mew's Hospital, West Smithfield, London ECIA 7BE 12 h) was 23.90 ,ug I1 h on day 0. The mean values on day 1 (24.30 ,ug I1 h) and day 8 (22.31 Acipimox is a recently developed antilipolytic g±g 1-1 h) were not significantly different (P > nicotinic acid analogue useful in the treatment 0.1). The mean digoxin renal clearance was 86 of type II and type IV hyperlipidaemia (Fuccella ml min- ton day 1 and 80 ml min-'on day 8 (P > et al., 1980). Hyperlipidaemia is a risk factor 0.1). for ischaemic heart disease and the latter may This study has not shown a significant effect of require digoxin therapy. It is important to find acipimox on digoxin pharmacokinetics. out whether acipimox interacts significantly with such therapy. We are grateful to the nursing staff on the Day ward After approval by the local ethical and Paget ward for their cooperation. We acknowledge committee, the supply of acipimox by Farmitalia Carlo Erba. six patients on digoxin were recruited (four male, two female, age range 63 to 82 years). Serial plasma samples for measurement of digoxin con- 4.0 centration were taken between 0 and 24 h on day 3.5 were a dose 0. The patients then given single oral E 3.0 of 250 mg acipimox following which the 24 h CD digoxin plasma concentration profile was re- C 2.5 peated (day 1). The patients then took acipimox o 2.0 250 mg three times daily for a week following _ 1.5 which digoxin plasma levels were measured be- m tween 0 and 36 h (day 8). Twenty-four hour and 1.0 36 h urine collections were carried out on days 1 X 0.5 I II and 8 respectively. Digoxin levels were measured nnu.uIL. kit 0 2 4 6 8 10 12 14 16 18 20 22 24 with a magnetic antibody immunoassay Time (h) (Serono diagnostics). Results were analyzed using the paired t-test. Figure 1 Mean digoxin concentrations on days 0 (o), There was no significant difference in the 1 (0) and 8 (0). patients' clinical condition, electrocardiograms Proceedings ofthe BPS, 9-11 September 1987 103P Fuccella, L. M. etal. (1980). Clin. Pharmac. Ther., 28, Johnston, A. & Woollard, R. C. (1983). J. pharmac. 790. Methods, 9, 193.

Ketanserin in essential hypertension: pharmacokinetic and pharmacodynamic model individual response and concentration-effect (Holford et al., 1981) was used to characterise relationships the response to ketanserin for each individual in terms of BP reduction per unit drug concentration R. DONNELLY*, H. L. ELLIOTT, and to describe the temporal discrepancy for the P. A. MEREDITH & J. L. REID plasma concentration-effect relationship (keq). University Department of Materia Medica, Stobhill Using the linear effect model the reduction in Hospital, Glasgow G21 3UW BP in individual patients was well correlated with the plasma ketanserin concentration and Although maximal blood pressure reductions the mean responsiveness to ketanserin was -0.47 have been correlated with peak plasma concen- ± 0.24 mm Hg ng-1 ml-1 following the first dose trations of the serotonin(5HT2)-antagonist, and -0.25 ± 0.10 after 1 month. There was an ketanserin (Persson et al., 1987), in common apparent reduction in the responsiveness to with other antihypertensive drugs no direct con- ketanserin during chronic compared with single centration-effect relationship has been identified dose administration but this was associated with in individual hypertensive patients. a significant increase in keq from 0.49 ± 0.23 h-1 In a single blind study nine essential hyper- (first dose) to 1.86 ± 1.79 (1 month) and an tensives (SM, 4F; 45-61 years) with a mean entry increase in the AUC and elimination half-life for supine BP of 174/102 ± 12/7 mm Hg received 2 ketanserin during chronic treatment (Donnelly weeks treatment with placebo, then ketanserin et al., 1987). Thus, the overall concentration- 40 mg twice daily for 4 weeks. To evaluate the effect profiles following the first dose of ketan- effects of placebo, first dose and 1 month ketan- serin were comparable to those at steady state. serin, patients attended for three 8 h study days The responsiveness to ketanserin was unrelated during which BP and HR were measured at to patient age or the pretreatment plasma renin frequent intervals and venous blood sampled for activity. plasma drug and metabolite concentrations, renin This study has characterised the responses activity, aldosterone and catecholamines. The to acute and chronic ketanserin in individual haemodynamic effects and pharmacokinetic hypertensive patients. The derived concentration- results for the group have been described else- effect parameters are potentially useful for in- where (Donnelly et al., 1987), but we now con- vestigating the intersubject variability in anti- sider in further detail the kinetic-dynamic rela- hypertensive effect, and for optimising drug tionships in individual patients. An integrated therapy in individual patients.

Donnelly, R. et al. (1987). Br. J. clin. Pharmac., 24, Persson, B. et al. (1987). Eur. J. clin. Pharmac., 32, 599. 259. Holford, N. H. G. etal. (1981). Clin. Pharmacokin., 6, 429.

The chronopharmacology of and heart rate and that this variability, in part, a-adrenoceptors in man involves the adrenergic nervous system. How- ever, there is little information about circadian D. J. SUMNER*, J. VINCENT, H. L. ELLIOTr & changes in adrenoceptor responsiveness and this J. L. REID study was designed to investigate possible changes University Department of Materia Medica, Stobhill in peripheral cx1-adrenoceptors using the al- General Hospital, Glasgow G21 3UW adrenoceptor agonist, phenylephrine. Eleven healthy normotensive males, age range It is well recognised that there are circadian 19-43 years, received incremental infusions of variations in the regulation of blood pressure phenylephrine on several occasions: in the 104P Proceedings ofthe BPS, 9-11 September 1987 morning (08.00-10.00 h), afternoon (15.00- morning, 1.64 ± 0.5 in the afternoon and 1.83 ± 17.00 h) and evening (22.00-24.00 h) on a single 0.55 in the evening. While there is a trend for study day and at the corresponding times on a circadian effect with an apparently reduced three further study days. Each infusion study sensitivity later in the day, analysis of covariance consisted of between four and six dosage incre- showed that there were no significant circadian ments, with each dose level being maintained for effects or carry over effects from previous in- 7 min, during which time heart rate and blood fusions, if the starting blood pressure was in- pressure were measured at 1 min intervals. At cluded as a covariate. the start of each infusion study, venous blood Although the value of starting blood pressure samples were withdrawn for measurement of accounted for some of the variability in the circulating hormones including catecholamines, pressor responses, there remained a consider- cortisol and plasma renin activity. able intra-subject variation which could not be The changes from baseline in blood pressure accounted for by any of the measured variables. were fitted to a quadratic function (Sumner et While it is essential to be aware of the possibilities al., 1982) and the dose of phenylephrine (jig kg-' of circadian changes these results indicate the min-1) required to raise systolic pressure by 20 necessity for standardisation of the laboratory mm Hg (PD20) was calculated for each individual conditions so as to minimise as many sources of dose response curve. On separate days, the mean variability as possible. values (± s.d.) of PD20 were 1.52 ± 0.66 in the

Sumner, D. J. et al. (1982). Clin. Pharmac. Ther., 32, 450.

Effect of cyclopenthiazide on glucose tolerance and plasma lipoproteins in mild 75 g ofglucose during a 2 h oral glucose tolerance essential hypertension test. Patients were then randomly assigned to receive placebo, 50 ,ug, 125 ,ug, or 500 ,ug of G. E. McVEIGH*, E. DULIE & G. D. JOHNSTON cyclopenthiazide for 8 weeks, when the above Department of Therapeutics and Pharmacology, The tests were repeated. Blood pressures were Queen's University of Belfast, and *Department of checked at 2 weekly intervals throughout the Clinical Chemistry, Belfast City Hospital, Belfast trial. Statistical analyses were carried out using analysis ofvariance and Scheffe's multi compari- Numerous clinical trials have demonstrated that son test. Values are expressed as mean ± s.e. treatment of essential hypertension with thiazide mean. diuretics will reduce the incidence of stroke, The two larger doses of cyclopenthiazide pro- congestive cardiac failure, and renal failure duced comparable antihypertensive effects, after (Moser, 1984). The inability to show a corres- 8 weeks therapy. Baseline and follow-up values ponding reduction in the incidence of coronary for areas under the glucose and insulin curves heart disease has been partly attributed to the and glycosylated haemoglobin concentration upset in glucose tolerance and lipid and lipo- were similar to placebo and 50 ,ug medications. protein profile produced by these drugs (John- Corresponding values with the 125 ,ug and 500 ,ug son et al., 1986). As part of a double-blind doses were 13.5 ± 0.8 -* 14.0 ± 0.8 and 13.6 + placebo controlled study to investigate the anti- 0.9 13.6 ± 0.9 for glucose areas, 104 ± 15 - hypertensive efficacy of low vs conventional dose 103 ± 16 and 90 ± 17 -* 113 ± 19 for insulin cyclopenthiazide, we monitored drug effect on areas, and 6.3 ± 0.2 -*6.6 ± 0.4 and 6.1 ± 0.3 -) these parameters. 6.8 ± 0.4 for glycosylated haemoglobin concen- After a 4 week placebo run-in period, 53 tration respectively. patients with diastolic blood pressures between Pretreatment and follow-up values for the 90-110 mm Hg attended for study. After a 12 h important total cholesterol vs high density lipo- overnight fast, venous blood samples were taken protein cholesterol ratio were 6.9 ± 2.3 -* 7.7 ± for estimation of serum lipid, lipoprotein, apo- 3.4, 7.8 ± 2.8-* 7.1 ± 3.7, 6.7 ± 2.7-¶* 6.8 ± 2.2, lipoprotein and glycosylated haemoglobin levels 5.9± 1.7-6.1 ± 1.6forplacebo, 50 ,ug, 125 ,ug, Glucose and insulin levels were estimated prior and 500 ,ug preparations of cyclopenthiazide re- to, and at half-hourly intervals after, ingestion of spectively. Proceedings of the BPS, 9-11 September 1987 105P In conclusion, no detrimental effect on the group of essential hypertensive patients after 8 metabolic profile could be demonstrated with weeks therapy. any dose of cyclopenthiazide employed in this

Table 1 Changes in serum lipids and lipoproteins before and after 8 weeks therapy with cyclo- penthiazide (mean ± s.e. mean) Total cholesterol Total triglyceride HDL-C LDL-C Group (mmol 1-') (mmol 1-') (mmol 1-') (mmol 1-') Placebo Before 5.4 ± 0.3 1.3 ± 0.2 0.9 ± 0.1 4.1 ± 0.1 (n = 11) After 5.2 ± 0.2 1.3 ± 0.2 0.8 ± 0.1 3.9 ± 0.1 50pug Before 6.4 ± 0.2 1.5 ± 0.2 0.9 ± 0.1 5.0 ± 0.1 (n = 12) After 6.2 ± 0.2 1.6 ± 0.2 1.1 ± 0.1 4.6 ± 0.1 125 ,g Before 6.1 ± 0.2 1.5 ± 0.2 1.0 ± 0.1 4.5 ± 0.1 (n = 13) After 5.9 ± 0.2 1.7 ± 0.3 1.0 ± 0.1 4.3 ± 0.1 500 jig Before 5.1 ± 0.3 1.0 ± 0.1 0.9 ± 0.1 3.8 ± 0.1 (n = 11) After 5.2 ± 0.2 1.2 ± 0.2 1.0 ± 0.1 3.8 ± 0.1

Johnson, B. F. et al. (1986). J. Hypertension, 4, 235- Moser, M. (1984). Arch. int. Med., 144, 789. 239.

Angiotensin converting enzyme inhibition freshly prepared solutions of 0.9% NaCl con- potentiates the effects of intradermal brady- taining 0, 1.5, 3, 6 and 12 ,ug bradykinin were kinin in hypertensive patients injected into the volar aspect of the forearm at 5 min intervals. Skin thickness was measured R. E. FERNER*, D. WILSON & M. D. RAWLINS before and 20 min after injection, using modified Wolfson Unit of Clinical Pharmacology, Royal Victoria Harpenden callipers, and responses were cor- Infirmary, Newcastle upon Tyne NE1 4LP rected for increase in thickness due to saline alone. Angioedema, cough, wheeze, flushing and diar- Results are shown in Figure 1. Repeated rhoea in patients treated with angiotensin con- measures analysis of variance showed a signifi- verting enzyme (ACE) inhibitors, may be cant dependence of response on dose (F = 50.3, mediated by bradykinin. We have previously d.f. = 3, 54, P < 0.0001) and a significant dif- demonstrated that in normal volunteers, single ference between groups (F = 21.7, d.f. = 1, 18, oral doses of captopril or enalapril enhance the P = 0.0002) but no interaction of group with effects of intradermal bradykinin (Ferner et al., dose (F= 1.81, d.f. = 3, 54, P= 0.16). Five of 10 1987). To study these effects during therapeutic subjects taking ACE inhibitors flushed within 3 use, responses to intradermal bradykinin in min of one or more injections but no flushing hypertensive patients whose therapy included occurred in the other group (P = 0.05, Fisher's captopril (six patients) or enalapril (four patients) exact test). It is concluded that the effects of were compared with those in 10 hypertensive intradermal bradykinin are enhanced in hyper- patients whose treatment did not include an tensive patients treated with ACE inhibitors ACE inhibitor. Age (mean ± s.d.), 57 ± 13 and thus rendering them susceptible to adverse 52 ± 10 years and ratio of males to females, 5:5 effects mediated by bradykinin. and 4:6, were similar in the two groups. 100 ,ul 106P Proceedings of the BPS, 9-11 September 1987

2.5w

2.0 =

E 0 (A 0)011.51- c

1.01-

1.5 3.0 6.0 12.0 Bradykinin dose (p.g) Figure 1 Responses (mean ± s.e. mean) to bradykinin in hypertensive patients on ACE inhibitor (A) orother (A) therapy.

Ferner, R. E. et al. (1987). Br. med. J., 294, 1119.

Inhibition of 5-HT induced axon-reflex over study, eight healthy male volunteers aged 21- flares by BRL 43694, a novel 5-HT3 receptor 42 years and weighing 62-86 kg were examined. antagonist The study received prior approval from an in- dependent Ethics Committee and volunteers S. M. COOPER, B. D. C. ARNOLD & provided prior written informed consent. Flares W. G. RAPEPORT* were induced by duplicate intradermal in- Human Pharmacology Unit, Beecham Pharma- jections (0.05 ml) of 5-HT 4 x 10-5 mol I1 at ceuticals Research Division, Coldharbour Road, randomly selected sites on the back (Arnold et Harlow, Essex CM19 5AD al., 1988). Five minutes after injection, outlines of the flares were traced onto transparent acetate BRL 43694, endo-N-(9-methyl-9-azabicyclo[3,3,1] sheets and their areas measured using a micro- non-3-yl)-1-methyl-indazole-3-carboxamide, is computer based planimeter. 5-HT flares were a potent and selective 5-HT3 receptor antagonist induced before and 5 min, 1 h, 4 h and 24 h after which may have beneficial therapeutic effects in constant intravenous infusion over 30 min of 40 the treatment of vomiting resulting from cancer ,ug kg-1 BRL 43694 or matching placebo. Data therapy (Boyle et al., 1987). Studies using MDL comparsion was by Student's t-test for paired 72222 (Orwin & Fozard, 1986) and MDL 72422 samples between active and placebo treatments. (Heavey et al., 1986) have demonstrated that These data (Table 1) clearly demonstrate sig- blockade of 5-HT3 receptors by selective an- nificant reduction of the 5-HT induced axon- tagonists leads to inhibition of the axon-relief reflex flare for up to 24 h following single intra- flare response induced by intradermal 5-HT in- venous infusion of BRL 43694. This finding is jection. The flare is thought to result from the of special interest as it suggests a prolonged stimulation of excitatory 5-HT receptors situated pharmacological action of BRL 43694 which on cutaneous afferent neurones (Fozard, 1984). may be related to its suggested therapeutic action We wish to report a study in which we have as an antiemetic (Boyle etal., 1987). The measure- assessed the effects of an intravenous infusion of ment of the 5-HT axon-flare reflex may therefore BRL 43694 on 5-HT induced axon-reflex flares. provide a useful in vivo index of assessing the anti- In a double-blind, placebo-controlled cross- emetic actions of novel 5-HT3 antagonists in man. Proceedings of the BPS, 9-11 September 1987 107P

Table 1 Effect ofBRL 43694 on 5-HT induced flares (mean ± s.d.) following single dose intravenous infusion of BRL 43694 or matched placebo. Flare area (cm2) Time post-dose Predose 5 min +1 h +4h +24 h Placebo 9.58 ± 4.51 10.81 ± 6.36 10.40 ± 6.50 10.57 ± 5.34 11.52 ± 5.81 BRL 43694 10.26 ± 4.23 2.76 ± 2.89* 1.59 ± 2.08* 1.30 ± 1.53** 4.85 ± 3.60* *P < 0.01; **P < 0.001; paired Student's t-test (n = 8)

Arnold, B. D. C. et al. (1988). Br. J. clin. Pharmac., Heavey, D. J. et al. (1986). Br. J. clin. Pharmac., 21, 25, 126P. 558P. Boyle, E. A. et al. (1987). Br. J. Pharmac., 91, 418P. Orwin, J. M. & Fozard, J. R. (1986). Eur. J. Pharmac., Fozard, J. R. (1984). Neuropharmacology, 23, 1473. 30, 209.

The pharmacokinetic profile of BRL 43694, assayed for BRL 43694 by an h.p.l.c. method a novel 5-HT3 receptor antagonist, in with a lower limit of sensitivity in the region of 0.1 healthy male volunteers ng ml-1 (Clarkson et al., 1988). Approval from an independent ethics committee was obtained B. D. ZUSSMAN*, A. CLARKSON, P. E. COATES prior to initiation of the study. & W. G. RAPEPORT Plasma concentration profiles of BRL 43694 Beecham Pharmaceuticals Research Division, became log-linear by about 4 h. The proportion Coldharbour Road, The Pinnacles, Harlow, Essex of dose recovered unchanged in the urine was CM19 5AD low and variable (between 1.9 and 23.4%). Urinary recoveries and other pharmacokinetic BRL 43694, endo-N-(9-methyl-9-azabicyclo[3,3,1] parameters (Table 1) did not differ significantly non-3-yl)-1-methyl-indazole-3-carboxamide, is (P > 0.05) between dose level. Renal clearance a novel 5-HT3 receptor antagonist which, in contributed on average about 10% of total clear- ferrets, abolishes emesis evoked by cisplatin, ance and remained constant within volunteers. other cytotoxic drugs or by X-irradiation (Boyle Administration of the drug was well tolerated by et al., 1987). A randomised single-blind placebo- the volunteers and no significant adverse effects controlled study was performed to assess the were reported. There were no effects noted on intravenous pharmacokinetic profile and toler- haematology or clinical chemistry, and no alter- ance of BRL 43694 (administered as the hydro- ations in pulse or blood pressure. chloride salt). Two groups of healthy male In summary, intravenous infusion of BRL volunteers (age range 22-47 years) received 43694 to healthy male volunteers was well incremental doses of BRL 43694 at 2.5, 10 and tolerated. The parent compound was exten- 30 or 5, 20 and 40 ,ug pure free base kg-1 or sively distributed and rapidly cleared. Clearance matched placebo. Dosing was by constant rate was predominantly non-renal, with urinary intravenous infusion over a 30 min period with recoveries of unchanged BRL 43694 low and treatments separated by a minimum interval of 1 variable. The mean terminal phase half-life was week. Volunteers received the highest dosages about 4 h although, as with other pharmaco- during the final study session (30 and 40 jig kg-'), kinetic parameters, there was inter-individual and on this occasion blood and urine samples variability. In this limited study, no dose related were collected over a 48 h period for pharma- change in pharmacokinetics was apparent. cokinetic assessment. Plasma and urine were 108P Proceedings ofthe BPS, 9-11 September 1987 Table 1 Pharmacokinetics of BRL 43694 after i.v. doses (means and ranges) Dose level C30 min AUC. t½/, z Vd CL CLR (,ug pure free base kg-') (ng ml-) (ng ml-' h) (h) (1) (I h-) (1 h-') 30 16.9 63.6 3.9 235 44.5 3.42 (n = 6) (9.3-26.2) (40.4-89.7) (2.6-6.8) (178-314) (29.3-65.4) (0.87-6.11) 40 33.8 106 4.0 174 33.4 3.60 (n = 4) (24.5-43.0) (69.6-145) (2.5-7.1) (117-210) (20.4-48.6) (2.464.77)

Boyle, E. A. et al. (1987). Br. J. Pharmac., 91, 418P. Clarkson, A. et al. (1988). Br. J. clin. Pharmac., 25, 136P.

The effect of perioperative alfentanil and 1.5 mg kg-'. Anaesthesia was maintained with fentanyl on postoperative gastric emptying isoflurane in 67% N20 plus 02. Ten minutes after the completion of surgery the patients re- K. R. MILLIGAN*, J. P. HOWE, E. McCLEAN & ceived paracetamol elixir 20 mg kg- 1 and venous J. W. DUNDEE blood samples wre taken at 15 min intervals for Department of Anaesthetics, The Queen's University the next 120 min. These were analysed for para- and Mater Infirmorum Hospital, Belfast cetamol content using h.p.l.c. and the peak level, time to peak and the area under the curve (AUC Delayed gastric emptying, a well-recognised and 0-120 min) calculated for each patient. undesirable feature of opioid administration, is The groups were comparable with regard to of particular relevance in outpatient anaesthesia age, weight and duration of anaesthesia. The where postoperative analgesics or other medi- mean peak paracetamol levels in the alfentanil cation must be effective by the oral route. group were significantly (P < 0.01) lower than Although delay has been demonstrated with those of the control group. The mean time to intramuscular pethidine and morphine (Nimmo, achieve peak levels was longer in the opioid 1984) the effect of the newer shorter-acting treated groups than in the controls but the dif- opioids, alfentanil and fentanyl, has not been ferences were not statistically significant. The studied. The present study examines the effect AUC was less in both opioid series than in the of the preinduction administration of alfentanil controls but the difference only achieved signifi- and fentanyl on gastric emptying and compares cance with alfentanil. this with a non-opioid control group using para- The administration of alfentanil and fentanyl cetamol absorption as a means of assessing gastric produced changes in paracetamol absorption emptying (Nimmo et al., 1975). indicative of inhibition of gastric emptying. This Forty-five healthy women aged 18-55 years, achieved statistical significance only in the alfen- weighing 45-80 kg and undergoing minor gynae- tanil group. This was a surprising finding in view cological procedures were randomly allocated to of the longer action of fentanyl. The use of peri- one of three equal groups. Patients received operative alfentanil 5 ,ug kg-', in common with either alfentanil 5 p.g kg-', fentanyl 1 ±g kgt- or longer-acting opioids, is associated with signifi- no supplement immediately prior to the induction cant inhibition of gastric emptying. of anaesthesia which was with methohexitone

Table 1 Mean ± s.e. mean peak paracetamol levels, time to peak and AUC. Peak Time to peak AUC (,ug ml-') (min) (,ug ml-' min) Control 22.7± 1.3 59 ± 9 1871 ± 111 Alfentanil 16.0 ± 1.5* 75 ± 8 1271 ± 148* Fentanyl 21.6 ± 3.2 80 ± 8 1421 ± 189 *P < 0.01 (difference from control)

-Nimmo, W. S - (1984). Br. J. Anaesth -, 56, 29. Nimmo, W. S. etal. (1975). Br. J. clin. Pharnac., 2,509. Proceedings of the BPS, 9-11 September 1987 109P

Comparison of plasma concentrations by the infusion of either 25 ml h-1 of 0.08% or following epidural infusion of 0.08% and 8 ml h-' of 0.25% bupivacaine via an infusion 0.25% bupivacaine during labour pump (Imed 960). Each patient thus received 20 mg h-1. Venous blood samples were taken R. J. FLYNN*, T. J. McMURRAY, J. MOORE, from an indwelling cannula in the non-infused R. DWYER & J. W. DUNDEE arm at 0, 15, 30, 60, 90, 120, 180 and 300 min. Department of Anaesthetics, The Queen's University Bupivacaine analysis was by h.p.l.c. of Belfast, Belfast Data are presented as the mean in each series and the significance of the differences was calcu- Epidural analgesia has an established role for lated using the Mann Whitney U test. pain relief in labour. It has been suggested that The two groups of patients were comparable epidural infusions are safer than top-up doses in terms of mean age, weight and parity. Two and that the supervision of infusions is simpler patients in each group who experienced some (Taylor, 1983). Bupivacaine 0.08% solution discomfort during the 5 h sampling period re- infused at 25 ml h-1 has been shown to provide quired a single top-up dose of 30 mg after 3 h. long periods of uninterrupted analgesia (Tunstall From 30 min onwards the mean plasma levels & Ramamurthy, 1984). were significantly higher in those patients re- A recent report on the clinical effects of 0.08% ceiving the more concentrated solution (Table 1). and 0.25% solutions of bupivacaine administered The use of 0.08% solution bupivacaine was as continuous epidural infusions (Ewen et al., associated with fewer side effects than the more 1986) showed that the weaker solution produced concentrated solution. This could be related to better analgesia with fewer side effects. Both the lower plasma concentrations. Although the solutions were infused at a dose rate of 20 mg h-l. subjects received the same total dose of drug per Twenty patients who had requested epidural unit time the concentration gradient should be analgesia for labour were randomly allocated to greater with the 0.25% solution thus favouring receive either 0.08% or 0.25% bupivacaine. All tissue uptake. However, there was a greater gave informed consent and the prot6col was surface area for absorption with the higher volume approved by the University Medical Ethical of weaker solution. This study would suggest Research Committee. that the significantly lower plasma levels asso- After correct insertion of the epidural catheter, ciated with the weaker solutions reduces the risk an initial bolus of 50 mg (10 ml of 0.5%) bupi- of toxicity. vacaine was given. This was followed immediately

Table 1 Mean ± s.d. plasma levels of bupivacaine (ng ml-') during epidural infusion (n = 10) Infused concentration Time (min) 0.08% 0.25% p 15 553 ± 100 797 ± 344 NS 30 506 ± 104 738 ± 260 < 0.05 60 441 ± 106 731 ± 263 < 0,05 90 441 ± 119 721 ± 221 < 0.01 120 440 ± 151 712 ± 227 < 0.01 180 495 ± 205 723 ± 213 < 0.05 300 368 ± 146 677 ± 254 < 0.01

Ewen, A. et al. (1986). Anaesthesia, 41, 143. Tunstall, M. E. & Ramamurthy, C. (1984). Anaes- Taylor, H. J. C. (1983). Can. Anaesth. Soc. J., 30, 277. thesia, 39, 264. hlOP Proceedings of the BPS, 9-11 September 1987

A pharmacokinetic and dynamic study of for the two formulations. When AUC was cor- single nightly doses of conventional and rected for dose, there was no significant dif- controlled release formulations oftrazodone ference between the conventional and the con- trolled release preparations. S. J. WARRINGTON*, S. I. ANKIER & C.f.f.f. was reduced and postural sway in- Q. A. MEKKI creased by all treatments to a similar extent, with Charterhouse Clinical Research Unit, London no significant effect of the administration of EClM 6HR food. BP decreased after all treatments. How- ever, supine systolic BP and standing systolic In a double-blind study, pharmacokinetics and and diastolic BP were reduced to a greater extent dynamics of conventional and controlled release when either preparation of trazodone was taken formulations of trazodone were investigated in on an empty stomach than when food had been 12 healthy young volunteers (six men and six taken first (P < 0.05). Assessment of postural women). sway was complicated by a high incidence of The volunteers received four doses of trazo- inability to stand for the full duration of the done at 20.00 h at weekly intervals. The treat- measurement: of the 48 treatments given, this ments were trazodone 100 mg conventional phenomenon occurred after 22 (13 controlled capsule (Molipaxin) or 150 mg controlled release release, 9 conventional), whereas inability to tablet, either after fasting or 1 h after a standard stand during measurement of BP in the standing substantial meal. Frequent blood samples were position occurred after only three treatments. taken and blood pressure (BP) standing and We conclude that conventional and controlled lying, critical flicker fusion frequency (c.f.f.f.) release formulations of trazodone had similar and postural sway were measured at intervals effects. In view of the action on blood pressure, during the night and the following morning up to we recommend that both preparations of trazo- 14 h after the dose. The data were analysed by done should be administered after food. The analysis of variance. high incidence of fainting in this study is not The pharmacokinetic parameters for trazo- concordant with the results of clinical studies of done are shown in Table 1. The administration trazodone, and must reflect either differences of food before trazodone significantly affected between depressed patients and healthy volun- only Cma. (P < 0.05), but in opposite directions teers, or differences in study conditions, or both.

Table 1 Pharmacokinetic parameters for trazodone 100 mg conventional 150mg controlled release Fasting Food Fasting Food Cmax (p.g ml-') 1.19 0.92 0.90 1.08 tmax(median, h) 1.00 2.00 4.00 4.00 AUC(0-24) (,ug ml-' h) 6.85 7.16 10.35 11.50 AUC(O-oo) (ju.g ml-' h) 7.30 7.99 12.15 13.67 tv½ (h) 6.60 6.60 7.50 7.50

Pharmacodynamic and pharmacokinetic studies on the actions of two benzodiazepines and flupenthixol on human performance M. J. MATTILA*, M. E. MATTILA, K. ARANKO & T. SEPPALA1 Department of Pharmacology and Toxicology, Uni- versity of Helsinki, Helsinki 17, and 1 National Public Health Institution, Helsinki 28, Finland Proceedings of the BPS, 9-11 September 1987 lllP

Effect of some H2-receptor antagonists on In another set of experiments, the drugs were gastric emptying of solids in humans: are administered by intravenous infusion (cimeti- H2-receptors involved? dine 2 mg k 1- h-1, ranitidine and oxmetidine 0.5 mg kg- h-1). The infusion began 15 min C. SCARPIGNATO*, F. VITULO, G. ZIMBARO before the meal and continued for the entire & A. PEZZETTA period of the study (90 min). In both experi- Institute of Pharmacology, School of Medicine and ments, drugs and saline were administered Dentistry, University of Parma and Department according to a 4 x 4 latin square design. of Radiology and Nuclear Medicine, University of Finally, the effect of H2-receptor stimulation Messina, Italy with impromidine (the only H2-receptor agonist available for use in humans) was assessed in a Although cimetidine has no definite effects on third group of six volunteers. The compound human gastric emptying (for review see Bertaccini was administered by intravenous infusion (10 ,ug et al., 1980), ranitidine, administered by intra- kg-' h-1) as above. No significant difference venous injection, was shown to significantly delay was found between the emptying half-times emptying of solids (Scarpignato et al., 1982). obtained during impromidine or saline infusion The different behaviour of the H2-receptor (77.3 ± 4.2 min and 72.2 ± 1.8 min, respectively). antagonists suggested that the effect of ranitidine These data show that only high blood levels of may be independent of the H2-receptor blockade. ranitidine, as elicited by intravenous injection, To confirm this hypothesis, we studied the effect are able to delay gastric emptying and are in full of oxmetidine, another imidazoline H2-receptor accordance with the results obtained in duodenal antagonist, in comparison with the above men- ulcer patients (Corinaldesi et al., 1984). Further- tioned drugs, on gastric emptying time in two more, the inefficacy of cimetidine and oxmetidine groups of eight male volunteers. The H2-receptor (two H2-receptor antagonists) and of impromi- blockers were injected intravenously (cimetidine dine (a selective H2-receptor agonist) confirm 200 mg, ranitidine and oxmetidine 50 mg) before that this peculiar effect of ranitidine, not evident the administration of a standard mixed meal, the by intravenous infusion, is independent of the solid component of which was labelled with H2-receptor blockade. 99mTc-sulphur colloid (Scarpignato et al., 1982).

Table 1 Emptying half-times (min) Saline Cimetidine Ranitidine Oxmetidine i.v. injection 64.5 ± 5.8 65.9 ± 5.1 93.8 ± 13.3* 65.3 ± 5.4 i.v. infusion 64.9 ± 5.9 71.7 ± 6.8 71.7 ± 8.4 65.8 ± 5.7 *P < 0.02 in comparison with saline value

Bertaccini, G. et al. (1980). In H2-antagonists, eds Scarpignato, C. etal. (1982). Br. J. clin. Pharmac., 13, Torsoli, A. et al., pp. 251-261. Amsterdam: Ex- 252. cerpta Medica. Corinaldesi, R. et al. (1984). Int. J. clin. Pharmac., 22, 498.

The effect of REV 5901 on histamine and Drugs opposing the actions of leukotrienes may leukotriene D4 induced bronchoconstriction provide novel therapies in asthma. R,S-2-[3'- in man (1"-hydroxyhexyl)-phenoxymethylI quinoline (REV 5901) is a leukotriene antagonist and 5- J. M. EVANS*, N. C. BARNES, P. J. PIPER & lipoxygenase inhibitor in various animal models J. F. COSTELLO in vitro and in vivo. We have studied the effect of Department of Thoracic Medicine, King's College REV 5901 on histamine and leukotriene D4 School of Medicine and Dentistry, London SE5, (LTD4)-induced bronchoconstriction in a double- and Department of Pharmacology, Royal College of blind, placebo controlled, randomised, cross- Surgeons, London WC2 over trial. 112P Proceedings of the BPS, 9-11 September 1987 Eight normal males completed the study, 5901 had no effect on LTD4-induced broncho- which took place on 4 separate days. Baseline constriction. The geometric mean PC35 after lung function was measured on each day, consis- active drug was 7.1 x 10-5 mol I1 and after ting of forced expiratory volume in 1 s (FEV1), placebo 8.5 x 10-5 mol 1-1. The mean plasma specific airways conductance (sGaw), and flow concentration of REV 5901, when active drug at 30% vital capacity above residual volume was taken, was 612 ± 354 ng ml-' at 1 h post (Vmax30). REV 5901 (1 g) or matching placebo dosing and 227 ± 116 ng ml-1 at the end of was ingested and 1 h later the lung function was challenge. Considerable inter- and intra-subject repeated. Inhalation challenges were then per- variability in plasma concentrations was found formed with either LTD4 or histamine (Barnes et (coefficient of variability: 57.8% 1 h; 51.1% at al., 1987): sGaw and Vmax30 were measured 3 h). No serious adverse effects were demon- after each concentration. Dose-response curves strated but noisy borborgymi and nausea were were constructed, and the concentrations of noted on four out ofthe 16 occasions when active histamine and LTD4 producing a 35% fall in drug was taken and on two occasions when sGaw (PC35) or a 30% fall in Vmax30 (PC30), placebo was taken. were calculated by linear interpolation or extra- Despite the proven efficacy of oral REV 5901, polation. Blood samples were taken before, at as an LTD4-antagonist, at comparable doses in 1 h post-dose and at the end of challenge, for animal studies, we have been unable to demon- estimation of drug concentration using a gas strate any significant LTD4-antagonism in man. chromatographic technique. This study suggests that caution needs to be There was no significant change in either base- exercised in using animal models when LT- line lung function or in histamine dose-response antagonists are developed. The activity of REV curves. Some subjects showed a small shift in the 5901 as a 5-lipoxygenase inhibitor remains to be LTD4 dose-response curve, but overall REV assessed in man.

Barnes, N. C. et al. (1987). J. clin. All. Immun., 79, 816.

The effect of a single dose of inhaled eight male patients with mild asthma, in a double- L-648,051, a leukotriene D4 antagonist, blind, placebo-controlled, randomised, cross- in mild asthma over study. All those studied had: (1) docu- mented asthma with evidence of reversible air- J. M. EVANS*, N. C. BARNES, P. J. PIPER' & flow obstruction with a 132-adrenoceptor agonist; J. F. COSTELLO (2) values of forced expiratory volume in 1 s Department of Thoracic Medicine, King's College (FEVj) between 50 and 70% of predicted (range School of Medicine and Dentristry, London SE5 54.9-70.0%) with less than a 10% difference in and Department of Pharmacology, Royal College of FEV, between the two study periods (range: Surgeons, London WC2 0.4-9.0%). No systemic corticosteroids or anti- histamine drugs were allowed within 30 days, The activity of leukotriene antagonists in asth- and no non-steroidal anti-inflammatory drugs matic patients will help to clarify the role of within 7 days, of the study. Regular inhaled leukotrienes in the pathogenesis of asthma and medications (corticosteroids, disodium cromo- may lead to new therapies for asthma. glycate and 032-adrenoceptor agonists) were Sodium 4-[3-(4-acetyl-3-hydroxy-2-propyl- allowed until 6 h pre-study, and oral theophylline phenoxy)-propylsulphonyl] -y-oxobenzene- preparations were discontinued 36 h pre-study. butanoic acid (L-648,051) has been found to be a Pulmonary function was assessed by measuring: specific cysteinyl-leukotriene antagonist in dif- specific airways conductance (sGaw), flow ferent animal models both in vitro and in vivo. at 30% vital capacity above residual volume We have already shown that 1.6 mg of inhaled (Vmax30) and FEV1. Following baseline pul- L-648,051 partially inhibits the effect of inhaled monary function measurements, 16 inhalations leukotriene D4 in normal men (unpublished of an aerosol of L-648,051 (100 FJg/actuation) observations). or matching placebo were administered from a The effect on pulmonary function of a single, pressurised canister. Pulmonary function was inhaled dose of L-648,051 has been assessed in measured immediately afterwards and repeated Proceedings of the BPS, 9-11 September 1987 113P at 10 min intervals for the first hour and at 30 min were noted either clinically or from laboratory intervals for the subsequent 3 h. tests. Mild symptoms of throat irritation were L-648,051, had no significant effect on the found with equal frequency with both treat- three measurements of pulmonary function at ments. any time point, post-inhalation. Mean FEV, In male asthmatic patients, with mild airflow (± s.e. mean) values were for L-648,051 and obstruction, the acute administration of L-648,051 placebo respectively: pre-inhalation 2.60 (± 0.14) has not produced significant bronchodilation. and 2.53 (+ 0.13); immediately post-inhalation As L-648,051 is active as an LT-antagonist in 2.53 (± 0.13) and 2.49 (± 0.14); at 1 h 2.61 (± man and is well tolerated, it merits further study 0.16) and 2.57 (± 0.18) and at 4 h 2.69 (± 0.16) at higher doses and more prolonged administra- and 2.55 (± 0.23). No significant adverse effects tion in asthmatic patients.

POSTER COMMUNICATIONS Bronchodilator drug bioassay by whole body plethysmography in the normal and then waned linearly with time (6.20 ± 0.69 human subject x 10' (s.cmH2O)- min1). The rate of offset of effect was combined with the slope of the R. W. FOSTER & G. K. ATANGA relevant segment (0.32 to 1 mg) of the log dose- Smooth Muscle Research Group, Department of response curve (-3.07 ± 0.68 x 10-2% per e- Physiological Sciences, Medical School, University of fold concentration change) to estimate the half- Manchester, Oxford Road, Manchester M13 9PL time of decay of methacholine inhaled dose (about 35 min) and hence the maintenance dose Holgate et al. (1977) demonstrated the dosage (0.27 mg) and interdose interval (15 min), after a dependency of the bronchodilator effect of sal- loading dose of 1 mg methacholine, predicted to butamol in normal subjects. Using similar achieve a steady state maintained bronchocon- methods our attempt to construct a log dose- striction-actual slope was -1.23 ± 0.45 x 10-4 response curve to inhaled nebulized salbutamol (s.cmH20) min using only the bronchomotor tone inherent to Against this background bronchoconstriction, the normal human subject produced an all-or- 25 or 100 ,ug of nebulized inhaled salbutamol none response-the coefficient of variation was produced an increase in sGaw which was fully so large that intermediate responses were neither developed in 15-30 min and then slowly waned significantly larger than no response nor smaller approximately linearly with time. Cumulative than the maximal response. log dose-response curves to salbutamol (1.6-100 Over 90 control measurements, neither specific ,g) and reproterol (16-1000 ,ug) using multiples airways conductance (sGaw) nor log sGaw dif- of 4 every 15 min were examined as well as a fered in distribution significantly (P > 0.05) saline vehicle control in a balanced design (n = 5). from a normal one. Mean baseline sGaw over 5 Bronchoconstrictor and bronchodilator re- months showed a highly significant but rhythm- sponses revealed that the s.e. mean varied with less variation. the mean sGaw while log sGaw was homosce- The normal human subject was rendered suit- dastic-hence for the statistical analysis of bio- able for the demonstration (at high precision) assays log sGaw was the preferable response of log dose-response relationships to inhaled metameter. nebulized selective agonists at 32-adrenoceptors, For validation of the bioassay, analysis of and hence their bioassay for relative potency and variance was applied to the upper three doses of effectiveness, by the induction and maintenance each curve. There was no significant deviation of a constant degree of bronchospasm. from parallelism, deviation from linearity, differ- Methacholine was nebulized and inhaled in ence in curvature or difference between prep- doses ranging from 1 ,ug to 3.2 mg in multiples of arations (0.38 < P < 0.93). Linear regression 3.2 every 15 min. One mg caused a 67% reduc- and difference between treatments were highly tion in sGaw from 0.201 ± 0.004 (mean ± s.e. significant (P < 0.0001). Reproterol was 12.2 mean, n = 99) to 0.067 ± 0.002 s-1 cm H2O1 (n (95% confidence limits 7.6, 19.8) times less potent = 25). This effect was fully developed in 15 min than salbutamol. 114P Proceedings of the BPS, 9-11 September 1987 We thank Dr T. B. Stretton, Unit of Respiratory Medicine, Manchester Royal Infirmary, for the use of the whole body plethysmograph.

Holgate, S. T. et al. (1977). Lancet, ii, 375.

Inhibition of histamine induced broncho- histamine challenges performed predose and 2 constriction in normal healthy volunteers by and 5 h after dosing. These time points were a potassium channel activator, cromakalim, chosen as they corresponded with the anticipated BRL 34915 peak plasma concentration of salbutamol (2 h, Maconochie & Fowler, 1983) and cromakalim A. BAIRD, T. C. HAMILTON, D. H. RICHARDS, (approximately 4 h, Davies et al., 1988). Pulse T. TASKER & A. J. WILLIAMS and blood pressure were measured predose and Beecham Pharmaceuticals Biosciences Research then hourly for 8 h after dosing. Centre, Great Burth, Epsom, Surrey, KT18 5XQ Significant increases in PC40 values were found (P < 0.05, Wilcoxon signed rank test) 5 h after Cromakalim, (±) 6-cyano-3-4-dihydro-2,2- cromakalim and 2 h (P < 0.01, Wilcoxon signed dimethyl-trans-4-(2-oxo-1-pyrrolidinyl)-2H- rank test) after salbutamol. The mean log PC40 benzo[b]-pyran-3-ol, BRL 34915 is a smooth was also significantly increased (P < 0.01, t-test) muscle relaxing agent currently under develop- 5 h after cromakalim and 2 h (P < 0.01, t-test) ment for the treatment of hypertension in man. and 5 h (P < 0.05, t-test) after salbutamol. No It relaxes vascular and respiratory smooth muscle changes in PC40 or log PC40 were found after in vitro by opening Rb-permeable K+-channels placebo. There was a fall in the diastolic blood (Hamilton et al., 1986; Allan et al., 1986). In pressure and a slight increase in heart rate after addition cromakalim inhibits agonist induced both cromakalim and salbutamol compared with bronchoconstriction in anaesthetised and con- placebo. The maximum fall in diastolic blood scious guinea-pigs (Buckle et al., 1987). We have pressure was 6.5 ± 3.6 mm Hg after salbutamol therefore, examined the effect of cromakalim (2 h post dosing) and 9.4 ± 3.4 mm Hg after on histamine induced bronchoconstriction in cromakalim (5 h post dosing). The maximum healthy volunteers. increase in heart rate was 3.0 ± 6.1 beats min-' Seven healthy male volunteers received single after salbutamol (2 h post dosing) and 6.7 ± 6.2 oral doses of cromakalim (2 mg), salbutamol beats min-' after cromakalim (5 h post dosing). (4 mg 'Ventolin', Allen and Hanburys), and There were no significant differences in these placebo according to a randomized double-blind parameters between cromakalim and salbutamol crossover design, with 1 week between dosing treatments in these normotensive volunteers. days. Drugs were presented in two size 00 gelatin We conclude that 2 mg of cromakalim given capsules. The provocation concentration of orally inhibits histamine-induced bronchocon- histamine causing a 40% fall in the partial ex- striction in healthy volunteers. piratory flow rate (PC40) was obtained from

Allan, S. L. et al., (1986). Br. J. Pharmac., 89, 395. Hamilton, T. C. etal. (1986). Br. J. Pharmac., 88, 103. Buckle, D. R. et al. (1987). Br. J. Pharmac., Proceed- Maconochie, J. G. & Fowler, P. (1983). Curr. med. ings supplement, Oxford meeting, P182. Res. Opin., 8, 634. Davies, B. E. et al. (1988). Br. J. clin. Pharmac., 25, 136P. Proceedings of the BPS, 9-11 September 1987 115P

An initial comparison of salmeterol and squares. Blood pressure, pulse rate and ECG salbutamol against histamine-induced were measured until stable. One of the above bronchoconstriction in healthy subjects treatments was inhaled and the above measure- ments taken at 5 min intervals for 15 min and J. G. MACONOCHIE, J. K. FORSTER, then at 15 min intetvals for 1 h. A histamine P. FOWLER & M. THOMAS challenge test was carried out 1, 4, 8 and 12 h Glaxo Group Research Limited, Ware, Herts after treatment. Doubling concentrations of histamine were inhaled at 3 min intervals until a Salmeterol has been shown in animal studies to fall in FEV, of at least 15% was achieved or the be a selective P2-adrenoceptor agonist more top concentration of histamine 16 mg ml-' was potent than salbutamol and with a longer duration reached. of action (Ball et al., 1987). The aim of the The ranks of the PD15 data were subjected to present study was to confirm these findings in asymptotic chi-squared analysis at each post- man using a histamine provocation test. treatment time (Bennett, 1966). The effects Six healthy male subjects aged 21-41 years of the three treatments on histamine-induced (median age 26 years) participated in the study. bronchoconstriction are shown in Table 1. All subjects had been tested previously with Compared with placebo, salmeterol protected inhaled histamine and were known to respond subjects from the effect of inhaled histamine for with a reduction in forced expiratory volume in 12 h whereas salbutamol showed a protective one second (FEV1) of greater than 15% at a effect at 1 h only (P < 0.05). No clinically signifi- concentration of histamine acid phosphate of cant drug-related changes in any cardiovascular 4 mg mg-' or less inhaled over 30 s (PD15). variables or laboratory safety screens were seen. A double-blind, placebo-controlled, cross-over This preliminary study confirms the results study was carried out on 3 separate days at obtained in animals with salmeterol, namely that intervals of at least 6 days. Treatments investi- the drug has a long-lasting bronchodilator action gated were inhaled salbutamol 2 x 100 ,ug shots, in man. Studies in asthmatic subjects are in inhaled salmeterol 2 x 100 ,ug shots and inhaled progress, where it is expected that the broncho- placebo two shots from a metered dose pres- dilator dose will be lower than the dose tested in surised aerosol. Treatment order was determined this study. with reference to two randomised 3 x 3 Latin Table 1 The median PD15 (mg ml-') to inhaled histamine after placebo, salbutamol and salmeterol Time after treatment (h) 1 4 8 12 Placebo 3.0 4.1 3.6 2.2 Salbutamol 200 ,ug 13.6 4.6 3.1 1.1 Salmeterol 200 ,ug > 16 > 16 > 16 9.8

Ball, D. I. et al. (1987). Br. J. Pharmac., Proceedings Bennett, B. M. (1966). Biometrie-Praximetrie, 7, 79. supplement, Oxford Meeting, C115.

Felodopine modifies exercise-induced asthma al., 1980). This type of calcium antagonist may also have a beneficial effect on lung function in K. R. PATEL & E. M. PEERS' (introduced by patients with asthma, in contrast to 3-adreno- P. D. I. Richardson) ceptor blockers. We have examined the effect of Department of Respiratory Medicine, Western Infir- felodipine on resting bronchomotor tone and mary, Glasgow Gll 6NT and 'Astra Pharmaceuticals exercise-induced bronchoconstriction (EIB). Ltd, Kings Langley, Herts WD4 8DH EIB is a reproducible fall in forced expiratory volume in 1 s (FEVy) of at least 20% following Felodipine is an antihypertensive calcium an- exercise. tagonist of the dihydropyridine group (Ljung et This was a double-blind, randomised cross- 116P Proceedings of the BPS, 9-11 September 1987 over comparison in 10 normotensive asthmatic Felodipine did not affect resting broncho- subjects of 10 mg felodipine in oral solution, motor tone. However, the exercise-induced fall with identical placebo on separate study days. in lung function was reduced by felodipine (P < Subjects had at least 80% predicted for age, sex 0.01 Wilcoxon test). Subjects observed more and height; variation between study days was relief of exercise-induced symptoms and experi- less than 10%. The study was approved by the enced side-effects after felodipine. Six patients Hospital Ethics Committee of the Greater on felodipine complained of headache, with two Glasgow Health Board and informed consent of these feeling dizzy post-exercise. There was a was given by each subject. higher HR (P < 0.05) with a tendency to a lower Heart rate (HR), blood pressure (BP) and BP on the felodipine study day (NS). lung function (FEV, and forced vital capacity, Felodipine alleviated EIB in all subjects. This FVC) were measured before and 15 and 30 min was both statistically and clinically significant after treatment. At 30 min, an 8 min submaximal and of the order of the protection observed after exercise test (steady state running on a tread- inhaled sodium cromoglycate (Patel, 1983). mill) was performed. Measurements were re- Felodipine might protect against bronchocon- peated 1, 2, 5, 10, 15, 30 and 60 min after striction when used to treat hypertensives with exercise. co-existing airways diseases.

Table 1 FEV, and FVC (1) at baseline, 30 min post-drug and lowest values post- exercise, with % fall (n = 10; mean ± s.d.). Baseline 30 min Lowest % fall Placebo FEV, 3.1±0.8 3.1±0.8 2.4±0.8 24± 15 FVC 4.2 ± 1.0 4.3 ± 1.1 3.5 ± 1.0 17 ± 17 Felodipine FEV, 3.2 ± 0.8 3.3 ± 0.9 2.9 ± 0.9 9 ± 13 FVC 4.4±1.2 4.4±1.2 4.1±0.9 6±11

Ljung, B. et al. (1980). Blood Vessels, 17, 154. Patel, K. R. (1983). Br. med. J., 285, 606.

Concentration-effect relationship for adenosine-induced respiratory stimulation The study was approved by the local hospital P. G. REID, A. H. WATT, P. A. ROUTLEDGE & ethics committee and all patients gave informed M. R. STEPHENS' consent. Seven patients undergoing cardiac Department of Pharmacology and Therapeutics, catheterisation for investigation of chest pain University of Wales College of Medicine and 'Depart- received i.v. infusion of adenosine via a femoral ment of Cardiology, University Hospital of Wales, vein (2 min stepwise increments in the range Cardiff 4.3-16.8 mg min-1 until limited by symptoms; prior to their diagnostic contrast studies. Prior to Adenosine stimulates respiration (Watt & the infusion and during the last 45 s of each stage Routledge, 1985; Reid et al., 1987) and poten- the heart rate (HR), i.a. BP and minute ventila- tiates the ventilatory response to hypoxia (Max- tion (V; determined by respiratory inductance well et al., 1986), probably through an action plethysmography) were measured and blood within the carotid body (McQueen & Ribeiro, was sampled from the aortic arch via a catheter 1981; Watt et al., 1987). It has therefore been for measurement of plasma adenosine concen- proposed that adenosine may be a physiological trations. Samples were drawn into syringes pre- mediator of the ventilatory response to hypoxia, filled with an ice-cold solution containing Dilazep but whether the observed effects of adenosine (0.13 mmol l-1) and EHNA (0.01 mmol '-1) to occur at physiological concentrations is not prevent metabolism of adenosine. After separa- known. We have investigated this by measuring tion and deproteinisation of plasma and derivati- adenosine concentrations in blood samples from sation of adenosine to 1, N6-etheno-adenosine the aortic arch during adenosine induced hyper- samples were analysed by h.p.l.c. using fluoro- pnoea. metric detection. Proceedings of the BPS, 9-11 September 1987 117P Comparing values at baseline with those at the The finding that V changed at plasma adeno- maximum dose of adenosine received by each sine concentrations similar to those reported in subject: plasma adenosine concentration in- man in the presence of hypoxia and ischaemia creased from 0.073 ± 0.032 (mean ± s.d.) to (Sollevi, 1986) is consistent with the hypothesis 1.198 ± 0.533 ,umol 1-1 (P < 0.002; paired t- that adenosine release within the carotid body test), V increased from 5.5 ± 1.91 to 10.9 ± 3.261 mediates the ventilatory response to hypoxia, min-1 (P < 0.01) and HR increased from 61 + but also raises the possibility that alterations in 12.2 to 72 ± 13.5 beats min-' (P < 0.01). BP did circulating adenosine concentration may affect not change. Measured variables returned to values respiration. similar to baseline 2 min post-infusion. There was a significant correlation between We are grateful to Dr L. Penny and Dr A. C. Newby change in V and change in log plasma adenosine for providing details of the assay and to Mr D. C. Buss concentration (r = 0.716, P < 0.001). for technical assistance.

Maxwell, D. L. et al. (1986). J. appl. Physiol., 61, Sollevi, A. (1986). Prog. Neurobiol., 27, 319. 1762. Watt, A. H. & Routledge, P. A. (1985). Br. J. clin. McQueen, D. S. & Ribeiro, J. A. (1981). Br. J. Pharmac., 20, 503. Pharmac.., 74, 129. Watt, A. H. et al. (1987). Br. J. clin. Pharmac., 23, Reid, P. G. etal. (1987). Br. J. clin. Pharmac., 23, 331. 486.

Loss of platelet activating factor from bronchoalveolar lavage fluid indicated a decrease in the levels of both PAF- acether and lyso-PAF after a further storage S.C. STENTON, E. N. COURT', D. J. HENDRICK, time of at least 28 days. To investigate the effects C. A. KELLY, E. H. WALTERS, P. GOADBY' & of handling and storage, PAF-acether (Sigma) W. P. KINGSTON1 was added to 2 ml aliquots of BAL samples Chest Unit, Newcastle General Hospital, University originally found to contain no PAF-acether to of Newcastle upon Tyne NE4 6BE and 'Department give a final concentration of 14.5 nm. PAF- of Pharmacology, Life Sciences Building, Sunderland, acether was then assayed after storage for (i) 1 h Polytechnic, SR1 3SD at 40 C and (ii) 10 days at -20° C. In a further series of experiments, PAF-acether was added We have previously demonstrated the presence to normal saline with and without bovine serum of platelet activating factor (PAF-acether) in albumen (0.25% w/v) to give a final concentration bronchoalveolar lavage (BAL) fluid from 4 of 17 of 14.5 nm and assayed after 10 days storage at asthmatic subjects but not in BAL fluid from -20 'C. PAF-acether levels (mean ± s.e. mean) subjects with emphysema and without bronchial after storage are shown in Table 1. hyperresponsiveness (Court et al., 1987). Subsequent BAL samples were extracted and We now present further data demonstrating the assayed more rapidly following lavage. PAF- presence of PAF-acether in BAL fluid from acether was detected in four of six asthmatic asthmatic subjects and describe its rapid dis- subjects and lyso-PAF was detected in five of six appearance during processing and storage. asthmatics. Lyso-PAF but not PAF-acether was BAL was performed in a middle lobe segment found in BAL fluid from three non-asthmatics. as described previously (Court et al., 1987) and Mean (± s.e. mean) levels of PAF-acether and following centrifugation, the cell free super- lyso-PAF in the asthmatics were 1.7 nm (0.8) and natant was stored at -20° C. PAF-acether was 4.2 nm (2.9) respectively. extracted from 5.4 ml aliquots of BAL fluid, half PAF-acether thus appears to be rapidly lost was acetylated for measurement of lyso-PAF during processing and storage and this may (Court et al., 1987) and both PAF-acether and account for our failure to detect it in the majority lyso-PAF were assayed on guinea-pig platelet of BAL samples. Further improvements in pro- rich plasma (Court & Kingston, 1987). cessing techniques may allow PAF-acether to be Re-examination of the four BAL samples detected in BAL fluid more readily. where PAF-acether had originally been detected 118P Proceedings of the BPS, 9-11 September 1987 Table 1 n PAF-acether (nM) BAL fluid, 1 h at 4° C 6 3.4 (0.7) BAL fluid, 10 days at -20° C 6 2.8 (0.4) Saline 10 days at -20° C 5 4.4 (0.7) Saline + BSA 10 days at -20° C 3 4.7

Court, E. N. & Kingston, W. P. (1987). Br. J. Pharmac., Court, E. N. et al. (1987). Br. J. clin. Pharmac., 24, 91, 409P. 258P.

Dipipanone and indomethacin: effects on (ANCOVA) using the pre-drug sessions as the electrically induced pain in volunteers covariate and t-tests, and significance taken as P < 0.05. Means of both post-drug sessions are R. L. HOLLAND, P. TAN, A. W. PECK & presented unless ANCOVA demonstrated a post- A. TELEKES drug session x treatment effect. Wellcome Research Laboratories, Beckenham, Kent Pain scores (in mm from the No pain end of the VAS) typically rose linearly after a delay- A safe and effective method to demonstrate pain 'Pain threshold' (PT). In nine subjects a plateau relief in healthy volunteers would be useful for was reached-'maximum pain' (MP), in six the the investigation ofputative analgesics. We have runs were terminated early 'tolerance limit' (TL). built and evaluated a new device for producing There were no significant treatment effects (mean pain by cutaneous electrical stimulation as this of all treatments ± s.e. mean) on ST (15.4 ± 2.4 technique can demonstrate drug effects (Stacher s), PT (24.5 ± 4.1 s), and MP (75 ± 6.1 mm). et al., 1986). However the six subjects who terminated their With ethics committee approval, 15 subjects runs early all had prolonged TL on the active participated in a double-blind, placebo (P) con- treatments-seen best at 180 min, (P = 58 s, D4 trolled crossover study of the opioid dipipanone = 78*, D8 = 75*, I50 = 69, I100 = 77*, SED = 4 and 8 mg, (D4, D8) and indomethacin 50 and 6.2, n = 6, *indicates P < 0.05). A dipipanone 100 mg (I50, I100) orally administered accord- effect was also seen on the ratio MP: TL (taken ing to a balanced design based on 5 x 5 Latin as 100 for the default scores) (P = 1.03, I50, = squares. Intervals between drug administration 1.04, I100 = 1.02, D4 = 0.87*, D8 = 0.89*, SED were at least 1 week. On each experimental day = 0.06). testing was done pre-drug and 90 and 180 min Significant treatment effects were seen on the post-drug. At each test session earlobe pain was Muzzy-Clear headed VAS (P = 134 mm, D4 = produced four times, with successive 100 s runs 123, D8 = 99*, I50 = 106*, I100 = 99*, SED = (starting at random intervals) of 10 Hz square 13.6) and Mentally Slow-Quick-witted scale wave current pulses, duration 1.8 ms, amplitude (P = 124 mm, I100 = 99*, SED = 11.6). Indo- rising by 6.25 ,uA per pulse. 'Sensation threshold' methacin produced a fall in resting end tidal (ST) was indicated by pressing a button, then Pco2 (P = 40.0 mm Hg, I50 = 39.0, 1100 = pain intensity was described by moving a com- 38.4*, D4 = 40.2, D8 = 40.5, SED = 0.5). Dipi- puter cursor along a visual analogue scale (VAS) panone reduced the minute ventilation when marked No pain-Max pain and 100 mm long. rebreathing CO2 at a Pco2 of 60 mm Hg (P = Cursor position was recorded at 0.5 s intervals. 20.0 1 min-', I50 = 21.6, I100 = 21.2, D4 = If the cursor reached max pain the run was 17.7*, D8 = 16.1*, SED = 1.1). terminated-'tolerance limit' (TL). Data from Both drugs affected the tolerance limit in the first run of the session were discarded, and doses producing respiratory and CNS effects. the means of the others analysed. Mental state Only dipipanone affected the pain ratio. Future was assessed using standard computer generated work will aim to increase the proportion of VAS (Telekes et al., 1987) and respiration subjects whose pain tolerance is exceeded, by was assessed by the Read (1967) technique. The selecting appropriate subjects and by altering data were subjected to analysis of covariance the stimulation parameters. Proceedings ofthe BPS, 9-11 September 1987 119P Read, D. J. C. (1967). Aust. Annals Med., 16, 20. Telekes, A. et al. (1987). Pain (in press). Stacher, G. etal. (1986). Br. J. clin. Pharmac., 21, 35.

In vivo opioid receptor binding in rats and 0.3-0.5 ,ug kg-l cold diprenorphine co-injected), man using [11CJ-diprenorphine using a LETI tomograph. High retaiiied uptake is seen in regions known, from post mortem A. K. P. JONES'23, S. K. LUTHRA', studies, to have high concentrations of opioid B. MAZIERE2, V. W. PIKE', C. LOC'H2 & receptors such as the thalamus, caudate, tem- D. STULZAFT2 (introduced by P. Turner) poral and frontal cortices. As expected there was 'MRC Cyclotron Unit, Hammersmith Hospital, rapid washout of activity from the occipital cortex. London, W12 OHS, 2SHFJ, Commissariat a l'Energie [I1CI-diprenorphine binding was shown to be Atomique, Department de Biologie, Hopital d'Orsay, reversed by saturating doses of naloxone (2 mg Orsay, France and 3Department of Rheumatology, St kg-") injected either prior or 30 min after injec- Bartholomew's Medical School, London EClA 7BE tion of tracer doses of ["CI-diprenorphine. The ratio of specific to non specific binding in the We have recently developed a technique for thalamus calculated from a naloxone displace- quantitating opioid receptor binding in man using ment study in one volunteer was 0.92 at 8 min the high affinity opioid antagonist ["C]-dipre- and 13.8, 65 min after injection of tracer. norphine (kD = 0.2 nM). The technique involves For comparison, ratios of specific/non specific the i.v. injection of ["C]-diprenorphine after binding in rats sacrificed 1 h after i.v. injection which its distribution in several transaxial sections of [3H]-diprenorphine were 10.5 (0.2 ,g kg-" through the brain is quantitated using positron cold diprenorphine co-injected) and of [1lC]- emission tomography. This technique has been diprenorphine were 11.8 (0.5 jig kg- cold described previously (Jones et al., 1985) in a diprenorphine co-injected). The similarity be- single volunteer injected with 0.5 mCi of ["1C]- tween the results with ["C]- or [3H]-diprenor- diprenorphine. We report here the results in phine in rats provides biological confirmation four normal volunteers injected with trace doses of the purity (> 98%) and identity of ["C]- of 5-10 mCi of high specificity activity ["C1- diprenorphine, as previously measured by t.l.c. diprenorphine (specific activity 187 mCi ,umol- and h.p.l.c. and NMR spectroscopy.

S *o .x .x "q8 .. -A .6

C,0 8X;*I qa -41

.I

:: L A.A AL.- A, P, "', l I., t I & I O I 0 I -I-,4, -I 30 60 90 0 Time (min) Figure 1 ["C]-diprenorphine in four normal volunteers.

Jones, A. K. P. et al. (1985). Lancet, ii, 8456. Maurer, R. et al. (1983). Life Sci., 33, Suppl 1, 231. 120P Proceedings of the BPS, 9-11 September 1987 Pharmacodynamics of a novel opioid using cold-induced pain (CP) with subjective peptide BW 443C in healthy volunteers ratings of pain intensity on a computerised VAS (Posner etal., 1984). Salivation was measured by J. POSNER, S. G. MOODY, A. W. PECK, dental roll weights and heart rate and blood G. RUT'ER & A. TELEKES pressure were recorded (Dinamap). Blood was Wellcome Research Laboratories, Beckenham, Kent sampled at intervals for assay ofplasma BW 443C, glucose, TSH, FSH, LH, PRL, GH and cortisol. BW 443C, Tyr.D.Arg.Gly.Phe(4NO2).Pro.NH2, All results were subjected to analysis of variance. is a novel enkephalin analogue with antinoci- Concentrations ofBW 443C had reached steady ceptive effects in animals thought to be mediated state when the first test battery was applied and at a peripheral site (Adcock et al., 1987; Follen- mean ± s.d. values for both occasions were 331 fant et al., 1987; Lorenzetti & Ferreira, 1987). ± 44 and 644 ± 84 ng ml'1 for LO and HI respec- In an open study in healthy volunteers central tively. BW 443C did not produce significant opioid effects were not evident with BW 443C central effects while DIP caused miosis and res- plasma concentrations > 1 ,ug ml-' (Posner et piratory depression (both P < 0.01). The peptide al., 1987). We now present results of a controlled did significantly reduce pain scores on the CP study in which the central, analgesic, cardio- test with the effect of DIP>HI>LO. Blood vascular and endocrine effects of two doses of pressure was decreased and heart rate increased BW 443C were compared with those of placebo on standing at the end of the rapid infusion but and a classical opiate dipipanone. these effects had resolved 20 min after slowing With an interval of at least 7 days between the infusion with no detectable differences occasions, 12 healthy male subjects received oral measured while sitting before CP tests. Blood dipipanone 10 mg (DIP), high (HI) or low (LO) pressure increases during the CP test were re- i.v. doses of BW 443C or placebo according to a duced by all active treatments (DIP>HI>LO). randomised, balanced, cross-over design with Consistent with complaints of dry mouth there double-dummy. HI was infused at 7.5 jxg kg-' was a significant reduction in dental roll weights min-' for 20 min and then 1.5 ,g kg-' min-' for with both doses of BW 443C and DIP (all P < a further 120 min and LO at half these rates in an 0.01). All active treatments increased plasma identical manner. On each occasion a test battery PRL (HI>LO>DIP, all P < 0.05) and reduced was performed twice starting 20 min after slow- cortisol; HI increased GH transiently (P < 0.05). ing the infusion and again 60 min later. Central In contrast to dipipanone, BW 443C reduced activity was assessed by pupil diameters, visual pain scores in a cold-pain model at concentra- reaction time, respiratory response to CO2 and tions which did not produce significant central self-ratings of alertness and mood on visual effects. The peptide may be an analgesic devoid analogue scales (VAS). Analgesia was studied of narcotic activity.

Adcock, J. J. et al. (1987). Br. J. Pharmac., 90, 143P. Posner, J. et al. (1985). Pain, 23, 73. Follenfant, R. L. etal. (1987). Br. J. Pharmac., 90, 68P. Posner, J. et al. (1987). Br. J. clin. Pharmac., 24, Lorenzetti, B. B. & Ferreira, S. H. (1987). Br. J. 266P. Pharmac., 90, 69P.

Trends in analgesic self-poisoning account for almost 50% of all cases of self- poisoning by the end ofthe study. The frequency J. McMURRAY', D. B. NORTHRIDGE2 & ofparacetamol poisoning rose tenfold during the A. A. H. LAWSON2 (introduced by A. D. Struthers) period of study and paracetamol is now the most 'Department of Clinical Pharmacology, Ninewells common analgesic taken by self-poisoners, Hospital and Medical School, Dundee and 2Miles- accounting for 12% of all overdoses and 24% of mark Hospital, Dunfermline, Fife, Scotland all analgesic overdoses. Aspirin poisoning, in contrast, declined sharply in incidence over the A 15 year prospective study of all admissions for 15 year period from 57% of all analgesic over- deliberate adult self-poisoning (n = 3516) to doses in 1971 to 14% in 1985. Distalgesic poison- a single district poisons unit in Scotland was ing also became much less common, decreasing undertaken. The proportion of analgesic over- from a peak of 24% of all analgesic overdoses in doses increased progressively over this period to 1978 to less than 1% in 1985. The most recent Proceedings ofthe BPS, 9-11 September 1987 121P change was a dramatic rise in the incidence of NSAID taken in overdose. This suggests mefen- poisoning with non-steroidal antiinflammatory amic acid is prescribed particularly to those at drugs (NSAID) from 5% of all analgesic over- risk of self-poisoning. Conclusions 1 and 2 high- doses in 1971 to 27% in 1985. Mefenamic acid light the importance of availability of a drug in its accounted for more such cases than all the other use by self-poisoners. As mefenamic acid has a NSAID in total (61% of all NSAID overdoses in particular danger in overdose, i.e. grand mal the 15 year period surveyed). convulsions, a reduction in its availability (i.e. When these results were analysed in conjunc- prescribing) to those who could be at risk of self- tion with the Scottish prescribing figures for poisoning might be considered. analgesic drugs the following conclusions were 3. The opposite trends in aspirin and para- reached. cetamol poisoning suggest that availability alone, however, is not the only factor influencing self- 1. Decreased prescribing of Distalgesic has poisoners. Perceived danger is probably also been associated with a similar decrease in self- important; for example the gastric side effects of poisoning with this preparation. The reduction aspirin are now widely appreciated. Such a per- in prescribing is attributed to increasing aware- ception may have reduced general aspirin usage ness of the toxicity of this compound taken in relative to paracetamol; if it has also had such excess. a dramatic effect on aspirin poisoning then 2. Increased prescribing of NSAID has been education of the public to the dangers of para- associated with increased poisoning with these cetamol in excess might have a similar beneficial drugs. Mefenamic acid is only the fifth most effect on self-poisoning behaviour with the latter commonly prescribed NSAID but the major drug.

Post-tetanic potentiation(PTP): a method of oxygen in nitrous oxide, halothane (1%) or en- evaluating an intense neuromuscular flurane (1-2%). Incremental doses of fentanyl blockade produced by atracurium in man (50-100 ,ug) were given to provide additional analgesia. Neuromuscular blockade was achieved F. A. WALI & A. H. SUER with atracurium (0.13-0.4 mg kg-'). Anaesthetics Unit, The London Hospital Medical The ulnar nerve was stimulated, supramaxi- College, Whitechapel, London El mally, at the wrist, and mechanical responses of the adductor pollicis muscle were recorded In addition to the use of train of four, twitch and isometrically (Bradshaw & Maddison, 1979). tetanic stimulations (Ali & Savarese, 1976; Indirectly-elicited twitch (1 Hz), train of four Payne & Hughes, 1981), the phenomenon of (TOF, 2 Hz, for 2 s every 12 s), tetanic (50 Hz for post-tetanic twitch potentiation(PTP) (Gissen & 1 s duration) and post-tetanic twitch response Katz, 1969; Wali & Suer, 1987), and its modified (PIT, 1 Hz) were recorded before and after version, i.e., post-tetanic twitch count (PTC) atracurium administration. The PTTl response (Viby-Mogensen et al., 1981), can be used to was elicited 5 s after a train of tetanic stimuli, monitor the degree of neuromuscular blockade e.g., at 50 Hz for 1 s duration. The PTP value produced by non-depolarizing muscle relaxants. was expressed as a percentage difference be- In the present investigation, we have used the tween the first twitch after the tetanus (PTT) and PTP method to assess and detect the degree of the last twitch before the tetanus (pre-tetanic neuromuscular blockade produced by atracurium twitch), thus PTP = (PTT-T)/T x 100. at a time when all other types of stimulations had The results showed that atracurium had a disappeared due to the intensity of muscle para- rapid onset of action (25 ± 2 s) and intermediate lysis. duration of action (18 ± 1.2 min). The twitch The patients (n = 8), male and female aged and train of four responses were blocked in 140 30-70 years, weighing 50-80 kg, were under- and 160 s, respectively (control values were 107 going minor orthopaedic surgery. Ethical com- ± 4.2 g and 127 ± 5.8 g, respectively, means ± mittee approval and informed consent from all s.e. mean, n = 8). The tetanus disappeared in patients were obtained. Anaesthesia was induced 240 s (control value, 307 ± 11.5 g), whereas the with di-isopropofol (1-2 mg kg-'), i.v., over 20 s, PTT response (control value, 120 ± 4.1 g) per- and the patients breathed no less than 30% sisted for 260 s. The PIT, thus, provides a more 122P Proceedings of the BPS, 9-11 September 1987 sensitive index for the degree of neuromuscular accordingly, were decreased with time and blockade during intense paralysis of the muscle. reached a value of 28 ± 5.1% in 20 min. Thus, The PTP values accordingly, were increased for a complete recovery process, the TOF re- with increasing intensity of blockade and reached sponse provides a more sensitive index than a value of 450 ± 31.5% (the pre-treatment value PTT. We conclude that during an intense neuro- was 12 ± 1.3%), in 2 min exposure to atracurium. muscular blockade, the PTP method can be During recovery process, the twitch and TOF more useful than the TOF in the detection of responses re-appeared last, i.e., in 16-18 min, the paralysis of the adductor pollicis muscle in the tetanus re-appeared in 14-16 min and the anaesthetized patients. PTT' re-appeared in 8-10 min. The PTP values,

Ali, H. H. & Savarese, J. J. (1976). Anesthesiology, Payne, J. P. & Hughes, R. (1981). Br. J. Anaesth., 53, 45, 216. 45. Bradshaw, E. G. & Maddison, S. (1979). Br. J. Viby-Mogensen, J. et al. (1981). Anesthesiology, 55, Anaesth., 51, 955. 458. Gissen, A. J. & Katz, R. L. (1969). Anesthesiology, Wali, F. A. & Suer, A. H. (1987). Eur. J. Anaesthesiol., 30, 481. 4, 45.

The effect of a single oral dose of lisuride, just before and at 1, 2, 3 and 4 h after drug terguride and bromocriptine on intraocular administration. Pupil diameter (using photo- pressure graphy), pulse and blood pressure were measured just before and at 1.5, 3 and 4.5 h after drug M. R. AL-SEREITI & P. TURNER administration. Department of Clinical Pharmacology, St Bartholo- The data were analysed using multiple regres- mew's Hospital, 38 Little Britain, London EClA 7BE sion analysis with the baseline IOP value included as a continuous independent variable together Bromocriptine, lisuride and terguride are semi- with treatment, time of measurement and sub- synthetic ergot derivatives with dopamine2- jects using the dummy variable technique. receptor (DA2) agonistic activity (Fluckgier & Considering all the post-treatment measure- Ringwald, 1982; Horowski & Wachtel, 1976; ments compared with placebo, lisuride decreased Wachtel & Dorow, 1983). IOP significantly in both right (1.2 mm Hg) (F Topical bromocriptine, lergotrile and per- (1,113) = 11.2, P < 0.005) and left (1.1 mm Hg) golide (dopaminergic agonists) reduced intra- (F(1,113) = 10.8, P < 0.05) eyes with maximum ocular pressure (IOP) in rabbits and monkeys effect at 4 h on the right (-2.3 mm Hg from the (Potter & Burke, 1983). This effect was inhibited baseline measurement) and at 3 h on the left by pre-treatment with domperidone (a selective (-2.1 mm Hg from the base line measurement). DA2-antagonist) and sympathectomy (Potter et Bromocriptine reduced IOP in both right (1.2 al., 1984). Bromocriptine also reduced IOP in mm Hg) (F (1,113) = 10.7, P < 0.005) and left healthy volunteers in a single 1.25 mg oral dose (0.9 mm Hg) (F (1,113) = 6.7, P < 0.01) eyes (Mekki et al., 1983) and using 0.025% eye drops and the maximum effect was at 4 h on both sides (Mekki et al., 1984). Pre-treatment with meto- (-2.6 mm Hg on the right and -2.3 mm Hg on clopramide (a DA2-antagonist) abolished this the left compared with the base line measure- effect (Mekki & Turner, 1985). ment). Terguride had no significant effect on Bromocriptine 1.25 mg, lisuride 0.1 mg, ter- IOP in both eyes. All treatments had no signifi- guride 0.25 mg or matched placebo, in a single cant effect on pupil diameter, pulse and blood oral dose, were given to eight healthy volunteers pressure. on four occasions, at least 1 week apart, in a The result of this study confirms the hypoten- randomised double-blind cross-over design sive effect of bromocriptine on IOP reported in based on two four-by-four latin squares. IOP animals and healthy volunteers and showed that was measured using the non-contact tonometer lisuride but not terguride has this effect.

Fluckiger, E. & Ringwald, E. (1982). Neuropsychiatr. Mekki, Q. et al. (1983). Lancet, i, 1250P. Clin., 1, 67P. Mekki, Q. et al. (1984). Lancet; i, 287P. Horowski, R. & Wachtel, H. (1976). Eur. J. Pharmac., Mekki, 0. & Turner, P. (1985). Br. J. Opthalmol., 69, 3, 373P. 909P. Proceedings of the BPS, 9-11 September 1987 123P Potter, D. E. & Burke, J. A. (1983). Curr. Eye Res., 2, Potter, D. E. et al. (1984). Curr. Eye Res., 3, 307P. 218P. Wachtel, H. & Dorow, R. (1983). Life Sci., 32, 421P.

Denbufylline and ethanol: effects on pleted the test battery. Raw data were analysed by psychomotor performance analysis of variance and Newman-Keuls multiple range test, values of P < 0.05 being taken as JULIA M. LOUDON, G. R. McCLELLAND & significant. ALISON J. PILGRIM Peak drug effects occurred 2-4 h after denbu- Human Phannacology Unit, Beecham Pharmaceuticals fylline/placebo treatment (i.e. 1-3 h after ethanol/ Research Division, Harlow, Essex CM19 SAD placebo). Ethanol alone significantly impaired performance on several parameters, whereas Denbufylline (BRL 30892; 7-(2-oxopropyl)-1,3- denbufylline alone did not significantly differ di-N-butyl xanthine) is a novel compound which from placebo. Combination of denbufylline with is active in animal models of cerebral vascular ethanol did not potentiate the ethanol impair- insufficiency and ageing (Nicholson & Angers- ment. Objective tests showing statistically signi- bach, 1986). It is currently being evaluated in the ficant ethanol effects were: tapping rate 2 h post treatment of dementia (O'Connolly et al., 1986). dose (mean ± s.d. taps min after placebo 401 In this study the objective and subjective psycho- ± 32, ethanol 357 ± 28, denbufylline 409 ± 38, motor effects of a single oral dose of denbufylline combination 349 ± 66), flash fusion 2 h post- have been compared with placebo, each alone dose (placebo 54.2 ± 6.4 ms, ethanol 61.4 ± and in combination with ethanol. 10.6, denbufylline 58.5 ± 6.9, combination 62.1 Twelve healthy volunteers aged between 29 ± 10.0) and RIPT 4 h post-dose (placebo 34.4 ± and 43 years completed four training sessions on 5.2/40 correct, ethanol 31.0 ± 8.7, denbufylline a test battery comprising: flash fusion threshold, 33.3 ± 5.7, combination 29.7 ± 7.3). estimation of a 1 min period of elapsed time, The most marked effects of ethanol were on manipulative motor task, tapping rate, two choice the VAS, where volunteers felt significantly more visual reaction time with auditory cues (which drowsy, feeble, muzzy, clumsy, discontented, were occasionally misleading), digit span, rapid troubled, lethargic, mentally slow, dreamy, in- information processing task (RIPT) and 16 visual competent, antagonistic, bored and withdrawn analogue scales (VAS) as described by Theo- at one or more timepoint, compared with placebo. filopoulos et al. (1984). All tests, except digit Denbufylline significantly attenuated some of span, were recorded via a CUBE microprocessor these effects of ethanol, particularly at 6 to 8 h system (McClelland et al., 1985). After training, post-dose. volunteers were randomly assigned to a latin Thus denbufylline, at the dose being evaluated square design of four treatments, each being in patients, did not significantly impair psycho- separated by a minimum of 7 days. Oral denbu- motor performance in normal volunteers. Den- fylline (100 mg) or matched placebo were admin- bufylline did not potentiate the impairment pro- istered 1 h prior to oral ethanol (0.8 g kg-') or duced by ethanol on objective measures and placebo. At pre-dose, and 2, 4, 6 and 8 h post even attenuated some of the subjective ethanol denbufylline/placebo dosage, the subjects com- effects.

McClelland, G. R. et al. (1985). Br. J. Pharmac., 84, O'Connolly, M. et al. (1986). In Pharmacology of 202P. cerebral ischemia, ed. Krieglstein, J. Amsterdam: Nicholson, C. D. & Angersbach, D. (1986). In Phar- Elsevier. macology of cerebral ischemia, ed. Krieglstein, J. Theofilopoulos, N. et al. (1984). Br. J. clin. Pharmac., Amsterdam: Elsevier. 18, 135. 124P Proceedings of the BPS, 9-11 September 1987 Central effects of the ,-adrenoceptor continuous attention, choice reaction time, finger antagonists propranolol and atenolol tapping, short term memory and immediate memory. Critical flicker fusion threshold and D. CURRIE, R. LEWIS & D. G. McDEVITT two flash fusion threshold were also measured. Department of Pharmacology and Clinical Pharma- Mood was assessed using a series of 12 visual cology, Ninewells Hospital and Medical School, Dundee analogue scales (VAS). Results were examined DD1 9SY by analysis of variance, and subsequent com- A. N. NICHOLSON & NICOLA A. WRIGHT parisons made between drug means and placebo Royal Air Force Institute of Aviation Medicine, Farn- means for each post-ingestion period. borough, Hampshire GU14 6SZ Two principal components were derived from the 12 VAS. Seven reflected mood and these Side effects of antihypertensive drugs are were unchanged by any treatment. The other potentially important since the benefits of five assessed changes in alertness, and scores for therapy to an individual with mild hypertension this component were reduced by oxazepam (P < are generally small. ,B-adrenoceptor antagonists 0.01) and atenolol (P < 0.05). Short term may have central effects (McDevitt, 1985; Salem memory, tested by recall of the content ofphoto- & McDevitt, 1983), but it is not clear whether graphs seen prior to drug ingestion, was im- their ancillary properties such as lipophilicity paired by 40 mg and 160 mg of propranolol (P < and selectivity are relevant. We have therefore 0.05) (Table 1). Oxazepam led to lower levels of compared the effects ofvarying doses of atenolol performance at letter cancellation and continuous (hydrophilic and pl-selective) and propranolol attention (P < 0.001), digit symbol substitution, (lipophilic and non-selective) on performance in finger tapping and immediate recall memory healthy male volunteers. (P < 0.05), but neither of the ,B-adrenoceptor After training to plateau level on all perfor- blockers affected these parameters. Critical mance tests, 12 subjects (mean age 22.2, range flicker fusion and two flash fusion threshold were 19-29 years) took single doses of propranolol not altered by any drug. (40 mg, 80 mg and 160 mg), atenolol (50 mg and These studies suggest that 3-adrenoceptor 100 mg), an active control, oxazepam (15 mg) antagonists have central effects in man, and that and two placebos. Treatments were separated hydrophilic antagonists are unlikely to be free of by at least 1 week and drugs were administered such effects. This conclusion is supported by in a randomised, double-blind manner. The drugs studies reported elsewhere (Nicholson et al., were taken orally at 11.00 h after a 24 h alcohol 1988), that the electroencephalogram is modified free period. Performance was assessed using 6 by both propranolol and atenolol, and these letter cancellation, digit symbol substitution, changes are consistent with sedation.

Table 1 Effect of ,B-adrenoceptor antagonists and oxazepam on memory and subjective alertness (mean values for 12 subjects) Oxazepam Propranolol Atenolol Placebo 15 mg 40 mg 80 mg 160 mg 50 mg 100 mg Short-term memory 7.4 7.8 6.3* 8.2 6.3* 7.5 6.5 Immediate recall 10.3 8.5* 9.7 9.9 9.8 9.9 10.1 Subjective alertness 0.311 -0.368** 0.350 0.067 0.156 {).352* 40.045 Significance levels: P < 0.05; **P < 0.01.

McDevitt, D. G. (1985). Eur. J. clin. Pharmac., 28 Salem, S. A. M. & McDevitt, D. G. (1983). Clin. (Suppl.), 35. Pharmac. Ther., 33, 52. Nicholson, A. N. et al. (1988). Br. J. clin. Pharmac., 25, 125P. Proceedings of the BPS, 9-11 September 1987 125P Effects of the ,-adrenoceptor antagonists propranolol and atenolol on the electro- All doses of both antagonists modified the encephalogram and on body sway electroencephalogram. The circadian rise in alpha activity which was observed with placebo A. N. NICHOLSON, NICOLA A. WRIGHT & from 13.00 to 15.00 h was reduced by both pro- M. B. ZETLEIN pranolol and atenolol (P < 0.05) and by oxazepam Royal Air Force Institute of Aviation Medicine, Fain- (P < 0.001). Atenolol also reduced beta activity. borough, Hampshire GU14 6SZ In the case of atenolol (P < 0.05) and oxazepam D. CURRIE & D. G. McDEVIIT (P < 0.01) these changes were associated with Department of Pharmacology and Clinical Pharma- subjective feelings of reduced alertness. The cology, Ninewells Hospital and Medical School, magnitude ofbody sway was increased by atenolol Dundee DD1 9SY and oxazepam (P < 0.05). The increase in body sway occurred in the low frequency component Central effects of the 3-adrenoceptor an- of the spectrum for oxazepam, while atenolol tagonists, propranolol (40, 80 and 160 mg) and modified the component of higher frequency atenolol (50 and 100 mg), were studied in 12 (Table 1). healthy male subjects (mean age 22.2 years). These observations on the EEG indicate that The study was double-blind, and included two both propranolol and atenolol have a sedative placebos and an active control, oxazepam (15 effect in healthy subjects, and that hydrophilic mg). Body sway and the electroencephalogram antagonists are unlikely to be free of such central (EEG) with eyes open and with eyes closed were activity. The observations on body sway suggest analysed together with subjective assessments of that postural mechanisms may be modified, at well-being. Drug ingestion was at 11.00 h and least with atenolol, and this raises the issue of a the schedule involved assessments before in- peripheral effect. gestion (09.00 h) and at 2 h (13.00 h) and 4 h (15.00 h) after ingestion.

Table 1 Effect of 13-adrenoceptor antagonists and oxazepam on the EEG, body sway and subjective alertness (mean values over dose and times for 12 subjects) Oxazepam Propranolol Atenolol Placebo 15 mg 40-160 mg 50-100 mg EEG (eyes open) (I V2) alpha 1 (7.5-10 Hz) 2672.2 1741.7*** 2250.8* 2263.9* alpha 2 (10.5-13 Hz) 964.6 644.3*** 775.5* 836.8* beta 1 (13.5-21 Hz) 970.5 765.8 733.3 742.1* tBody sway 0.05-2 Hz 0.3015 -1.0087* -0.1288 -0.0829 2.25-4 Hz 0.1833 -0.2752 0.0847 -0.5147* tSubjective alertness 0.3107 -0.3681** 0.1911 -0.1984* Significance levels: *P < 0.05, **P < 0.01, ***P < 0.001. tValues are scores on principal components representing body sway and alertness respec- tively. In the case of body sway, the weights are negative, and a decrease represents an increase in sway.

5-HT antagonists and slow wave sleep It has been demonstrated recently that the selec- tive 5-HT2 receptor antagonist, ritanserin, in- R. A. SOLOMON*, A. L. SHARPLEY & creases slow wave sleep (SWS) in sleep laboratory P. J. COWEN studies (Idzikowski etal., 1986). However, other University Department of Psychiatry and MRC Unit pharmacological studies in both animals and of Clinical Pharmacology, Littlemore Hospital, Little- man have indicated that the appearance of SWS more Hospital, Oxford OX4 4XN is dependent on intact brain 5-HT pathways 126P Proceedings of the BPS, 9-11 September 1987 (Idzikowski et al., 1986). One explanation for study nine subjects were randomised to receive this apparent paradox is that 5-HT receptor sub- in balanced order, cyproheptadine (4 mg), types may exhibit functional antagonism; for metergoline (4 mg) and placebo on 3 nights at example, in electrophysiological studies 5-HT2 21.00 h. Again each test night was separated by a receptor blockade can increase 5-HT1 receptor- 1 week interval. mediated responses (Lakoski & Aghajanian, Ritanserin increased SWS by a similar amount 1985). The present study was designed to test as that reported in sleep laboratory studies this hypothesis by investigating the effect of (Idzisowski et al., 1986). Cyproheptadine also ritanserin, cyproheptadine and metergoline on increased SWS in all subjects. In contrast, SWS. We predicted that ritanserin and cypro- meterogline did not significantly alter SWS. This heptadine would increase SWS but metergoline finding is consistent with the hypothesis that would not because it antagonises both 5-HT1 5-HT1 and 5-HT2 receptors play an antagonistic and 5-HT2 receptors (Leysen et al., 1981). role in the genesis of SWS. However, other Overnight sleep EEG recordings were made explanations including pharmacokinetic dif- in subjects' homes using the Oxford Medilog ferences between the drugs should also be con- EEG. Records were analysed by an automatic sidered. sleep stager. In the first study six volunteers were tested on two nights separated by 1 week ALS was supported by the Oxford Medical School receiving on one occasion ritanserin (10 mg) and Research Fund. Further support was given by Janssen on the other placebo, at 21.00 h. In the second Pharmaceuticals Ltd and Farmitalia Carlo Erba.

Table 1 Effects of 5-HT antagonists on slow wave sleep (SWS) Study 1 Study 2 Placebo Ritanserin Placebo Cyproheptadine Metergoline % SWS median 18.9 26.4* 17.2 24.1* 19.1 ± quartile deviation ±6.9 ±11.2 ±8.1 ±10.3 ±12.8 *P < 0.05 Wilcoxon signed rank test.

Idzikowski, C. et al. (1986). Brain Res., 378, 164. Leysen, J. E. et al. (1981). Life Sci., 28, 1115. Lakoski, J. M. & Aghajanian, G. K. (1985). Neuro- pharmacology, 24, 265.

An investigation of 5-hydroxytryptamine trations of 5-HT and its site of injection on the induced axon reflex flares in man size of induced axon reflex flares. Twelve healthy male volunteers, aged 24-58 B. D. C. ARNOLD, S. M. COOPER & years, were drawn from an established volunteer W. G. RAPEPORT panel. Volunteers attended for three sessions, at Human Pharmacology Unit, Beecham Pharmaceuticals weekly intervals, so that each received three Research Division, Coldharbour Road, Harlow, Essex series of six intradermal injections (0.05 ml) of CM19 5AD 5-HT, 1 x 10-5, 4 x 10-5 and 1.6 x 10-4 mol 1-1. The injections were randomised to duplicate The development of novel selective 5-HT3 sites on the upper, middle and lower back, so antagonists has led to the development of the that each of the sites received one dose of each axon-reflex flare response to intradermal 5-HT concentration over the three sessions. Five injection in man as an in vivo means of assessing minutes after injection, the time at which the 5-HT3 receptor antagonism (Orwin & Fozard, flare size appears to be maximal (Orwin & 1986; Cooper etal., 1988). The production ofthe Fozard, 1986), the outlines of the flares were axon-reflex flare is thought to be due to stimula- traced onto transparent acetate sheets and the tion of specific neuronal 5-HT3 receptors (Fozard, area measured using a microcomputer based 1984). We now wish to report a study in which video planimeter. The study received prior we have assessed the effect of varying concen- approval from an independent Ethics Committee Proceedings of the BPS, 9-11 September 1987 127P and volunteers provided written informed the areas of flares induced at different sites of consent. injection. The mean ± s.d. flare area for incremental These data demonstrate a dose-response 5-HT concentrations (1 x 10-5, 4 x 10-5 and 1.6 relationship between the concentration of 5-HT x i0'4 mol 1-1) were, respectively, 7.52 ± 3.41, used for intradermal injection and the resulting 9.09 ± 3.64 and 11.32 ± 4.23 cm2. Statistical axon flare area. It also suggests that the back analysis, by paired Student's t-test, demonstrated may be regarded as a single site, without the significant differences in mean flare area at each need for subdivision, when used for conducting incremental dose level (P < 0.001). axon reflex flare studies. There were no signiflcant differences between

Table 1 Results of paired Student's t-test analysis of flare areas 5-HT concentration Sample 1 Sample 2 d.f. t value P value 0-5 M 4 x 10-5 M 67 6.008 0.0001 10-5 M 1.6 x 10-5 M 65 12.525 0.0001 4 x 10-5 M 1.6x 10-5 M 65 5.849 0.0001

Cooper, S. M. et al. (1988). Br. J. clin. Pharmac., 25, Orwin, J. M. & Fozard, J. R. (1986). Eur. J. Pharmac., 106P. 30, 209. Fozard, J. R. (1984). Neuropharmacology, 23, 1473.

The effects of BRL 24924, a novel gastric 5-HT3 receptors in neuroendocrine function by prokinetic agent, on circulating hormone measuring circulating concentrations of nine concentrations in man hormones in subjects receiving oral treatment with BRL 24924 1.0 mg twice daily, for 28 days. W. G. RAPEPORT, S. M. COOPER, P. A. MAILE Eighteen healthy male subjects were recruited & F. H. PULLEN from an established panel for inclusion in a Human Pharmacology Unit, Beecham Pharmaceuticals double blind parallel group study. Treatment Research Division, Coldharbour Road, The Pinnacles, was provided by random allocation with a 2:1 Harlow, Essex CM19 SAD bias to active treatment. The study received prior approval from an independent ethics com- BRL 24924, (±)-endo-4 amino-5-chloro-2- mittee. Samples for hormone assay were obtained methoxy-N-(1-azabicyclo[3 ,3, 1]non-4-yl) from fasted individuals pre-dose and at 2 and 4 benzamide monohydrochloride, exhibits potent weeks after commencement of dosing, with a gastric prokinetic activity in animals and man follow-up assessment 2 weeks after completion without evidence of dopamine DA2 receptor of dosing (Week +6). Assays were performed antagonism (Cooper et al., 1986; Rapeport & using commercially available radioimmunoassay Thomson, 1987). BRL 24924 has recently been kits. shown to abolish cisplatin evoked emesis in the No changes in the concentrations of any of ferret by 5-HT3 receptor antagonism although these hormones were detected following admin- the contribution of this action to the prokinetic istration of BRL 24924 when compared with profile is not clear (Miner & Sanger, 1986). predose values, nor were significant differences Specific 5-HT receptors have been located in the found when compared with placebo (analysis by endocrine (but not neural) cells ofthe mammalian two way ANOVA), suggesting a lack of involve- pituitary (Payette et al., 1985). We have there- ment of 5-HT3 receptors in neuroendocrine fore attempted to determine the possible role of function. 128P Proceedings of the BPS, 9-11 September 1987

Table 1 Serum hormone concentrations [mean (± s.d.)] before, during and after dosing with BRL 24924 (A) or matched placebo (P) Weekspost dose 0 +2 +4 +6 Prolactin A 106 (68) 87 (44) 90 (30) 85 (30) (mu 1-1) P 78 (22) 92 (55) 78 (48) 114 (37) FSH A 4.3 (1.9) 4.4(2.5) 4.4(2.5) 4.1 (2.0) (iu l-') P 3.5 (1.6) 3.3 (1.1) 3.1 (1.3) 3.3 (0.9) LH A 5.7 (1.5) 5.2(2.8) 4.7(0.9) 4.7(1.3) (iu l-1) P 4.4 (2.1) 4.0 (1.3) 4.7 (2.2) 4.6 (1.9) TSH A 1.5 (0.5) 1.9 (1.1) 1.6 (0.7) 1.9 (0.9) (mu l-l) P 1.7 (0.6) 1.9 (0.7) 1.7 (0.4) 1.9 (0.7) Free T3 A 7.8 (1.8) 8.1 (1.7) 7.3 (1.2) 7.1 (0.8) (pmol l-l) P 7.6 (1.6) 7.8 (1.8) 7.5 (1.0) 7.1 (1.0) T4 A 73 (12) 74 (15) 82 (17) 81 (10) (nmol1-1) P 80 (7) 79 (5) 76 (15) 81 (18) Cortisol A 468 (169) 418 (98) 366 (95) 427 (238) (nmol 1-1) P 421 (115) 386 (110) 278 (67) 413 (145) Testosterone A 22 (6) 22 (8) 20 (6) 20 (6) (nmol 1-') P 22 (7) 23 (8) 20 (7) 17 (3) Progesterone A 4.3 (1.2) 4.8(1.4) 4.3(1.4) 5.0(1.4) (nmolI-) P 4.3 (1.3) 4.4(1.4) 3.8(1.3) 4.9(1.5)

Cooper, S. M. et al. (1986). Br. J. Pharmac., 88, 393P. Payette, R. et al. (1985). Endocrinology, 116, 1933. Miner, W. D. & Sanger, G. J. (1986). Br. J. Pharmac., Rapeport, W. G. & Thomson, S. (1987). Br. J. clin. 88, 374P. Pharmac., 24, 264P.

Spironolactone lacks efficacy in female hirsutism hirsutism, age of menarche and the presence of acne. Hair growth was assessed subjectively, A. R. McLELLAN*, J. RENTOUL, R. MACKIE & and objectively by computerised microscopic G. T. McINNES measurement of hair shavings taken from a University Departments of Medicine and Dermatology, 5 cm2 patch from one thigh; this area was other- Western Infirmary, Glasgow Gil 6NT wise untreated during the study period. In addi- tion, plasma concentrations of testosterone, Spironolactone at a daily dose of 50-200 mg has androstenedione, dehydroepiadrosterone sul- been advocated widely for the management of phate, sex hormone binding globulin, prolactin idopathic hirsutism (Boiselle & Tremblay, 1979; and the gonadotrophins were measured at Shapiro & Evron, 1980; Cumming et al., 1982; each assessment. Compliance with therapy was Evans & Burke, 1986; Tremblay, 1986), the assessed by measurement of plasma concen- presumed benefit being attributed to the drug's trations of canrenone, a metabolite of spirono- antiandrogenic activity. However, this practice lactone, and subjects were asked to report any lacks adequate experimental support: hitherto, adverse effects of treatment. Subjects were studies have either been entirely uncontrolled or studied prior to randomisation and at 6, 12, 24 control groups have been inadequate. and 36 weeks of treatment. Eleven pairs com- In this study, 38 patients with idiopathic pleted the entire protocol. hirsutism (age 18-45 years) were allocated Compared with placebo, hair shaft diameter randomly to double-blind treatment with spiro- was not altered significantly by spironolactone nolactone 100 mg daily or placebo for 9 months. (mean change +15%, 95% confidence intervals The subjects were matched in pairs primarily for -0.4% to +29.5%), where a positive change menstrual irregularity but also, as far as pos- indicates increased hair shaft diameter. Subjec- sible, for duration, family history and degree of tive assessment of the effect of spironolactone Proceedings of the BPS, 9-11 September 1987 129P suggested some benefit but this failed to achieve In contrast to previous reports, this placebo statistical significance (P < 0.1). When placebo controlled study provides no convincing evidence responses were taken into consideration, spiro- of a clinically useful effect of spironolactone in nolactone did not affect plasma concentrations hirsute females. Minor subjective improvement of any of the hormones measured. Plasma can- was noted by some patients but ancillary in- renone concentration showed wide interindivi- fluences of spironolactone on menstrual regularity dual variability but confirmed compliance in or on acne may have modified the individual's the actively treated patients. Adverse effects, assessment. Although well tolerated, nine primarily menstrual dysfunction, were as frequent months treatment with spironolactone 100 mg in the placebo group (n = 3) as in the spirono- daily is not associated with significant hormone lactone group (n = 3) and accounted for the changes and does not confer objective benefit in withdrawal of only three subjects. idiopathic hirsutism.

Boisselle, A. & Tremblay, R. R. (1979). Fertil. Steril., Shapiro, G. & Evron, S. (1980). J. clin. Endocrinol. 32, 276. Metab., 51, 429. Cumming, D. C. et al. (1982). J. Am. med. Ass., 247, Tremblay, R. R. (1986). Clin. Endocrinol. Metab., 15, 1295. 363. Evans, D. J. & Burke, C. W. (1986). J. Roy. Soc. Med.,79, 451.

Human colon mucosa: effect of marine oils on lipid fatty acid composition and eicosanoid were not available at all time points (a minimum synthesis in inflammatory bowel disease of 4 values at each time point). Statistics were performed by the rank sum test. Fatty acids are K. HILLIER, L. DORRELL, R. JEWELL & expressed as a percentage of the total major fatty C. L. SMITH acids present. Clinical Pharmacology Group, Medical Faculty, Uni- No significant changes were noted in the versity of Southampton, Southampton S09 3TU placebo group. After 3 weeks marine oil mucosal lipid C20:5 increased significantly (P < 0.05) Marine lipid (predominantly C20:5 and C22:6) from 0.34 ± 0.18% (mean ± s.d.) to 2.52 + supplementation of diets can alter lipid fatty acid 1.46%. Arachidonic acid fell significantly from composition in circulating blood cells, and can 10.02 ± 3.8% to 7.5 ± 3.18% (P < 0.05, n = 6) affect eicosanoid synthesis by altering the avail- and to 5.4 ± 3.0% (P > 0.05, n = 5) at 12 weeks. ability of precursor fatty acids and by inhibiting C20:3 also fell significantly from 1.45 ± 0.37% cyclo-oxygenase. Arachidonic acid (Pacheco et to 0.85 ± 0.19% after 3 weeks (P < 0.05). C22:6, al., 1987) and eicosanoids (Boughton-Smith & C18:2 and C18:1 did not alter significantly. PGE2 Hawkey, 1983; Stenson & Lobos, 1982) are in- and 6-keto-PGF10, fell in five out of six patients creased in inflammatory bowel diseases (IBD) between 0 and 3 weeks from 23.86 ± 18.0 (ng and may contribute to the disease. We, there- mi-l protein) and 15.87 ± 13.68 to 11.97 ± 7.28 fore, set up a pilot study to determine whether and 6.82 ± 5.94 respectively. TxB2 was 10.7 ± tissue lipid fatty acids and PG and TxA2 synthesis 6.1 at 0 time and 9.1 ± 4.6 after 3 weeks. in colon mucosa could be modified by dietary Because of variation in results these data did not marine lipid. reach a level of significance. In a 12 week study, six patients with active Colon mucosal fatty acids can be significantly IBD received 18 g/day marine oil (predominant and selectively altered by dietary marine oil. The fatty acids, 3.2 g/day C20:5; 2.2 g/day C22:6, 3.6 influence of mucosal fatty acid and eicosanoid g/day C18:1). Seven patients with active IBD changes on the long-term progress of the disease received a placebo. is under investigation. Diet and drug therapy were unrestricted. At 0, 3, 6, and 12 weeks, rectal biopsies were analysed This work was supported by the National Association for fatty acids by gas-liquid chromatography and for Colitis and Crohn's diseases and the Wessex for PGE2, 6-keto-PGF10 and TxB2 by RIA of Medical School Trust. Seven Seas Health Care pro- Krebs' supernatants following 30 min tissue in- vided the marine oil (maxEPA). cubation at 370 C (Awara et al., 1986). Samples 130P Proceedings of the BPS, 9-11 September 1987 Awara, W. et al. (1986). Immunology, 59, 557. Pacheco, S. et al. (1987). Clin. Sci. (in press). Boughton-Smith, N. K. & Hawkey, C. J. (1983). Gut, Stenson, W. F. & Lobos, E. (1982). J. clin. Invest., 69, 24, 1176. 494.

To compare the sulphasalazine/ lactulose solution BP or sulphasalazine (2 g) sulphapyridine and lactulose/breath were administered alone and together in a rice hydrogen methods of assessing oro-caecal pudding (200 g ) meal. A rise of 15 ppm in the transit time hydrogen tension or the first appearance of sulphapyridine was taken as indicating the arrival D. H. STANIFORTH & R. CORBETT of the head of the test meal at the caecum. Sub- Beecham Clinical Pharmacology Unit, West Middlesex jects attended fasting and were semirecumbent University Hospital, Twickenham Road, Isleworth, for 4 h post dosing. Breath samples were taken Middlesex TW7 6AF every 10 min and assayed for hydrogen content using an electro-chemical cell. Blood samples A variety of methods are used clinically to esti- for determination of sulphapyridine were taken mate oro-caecal transit time. Two of these at 1.66, 2.00, 2.33, 2.66, 3.00, 3.33, 3.66, 4.00, methods, the lactulose/breath hydrogen (L/BH) 4.33, 4.66, 5, 6, 7 and 8 h. The sulphapyridine and the sulphasalazine/plasma sulphapyridine was assayed by h.p.l.c. Results are given in (SLZ/SP) methods rely on the production of Table 1. hydrogen and sulphapyridine respectively by the Analysis of variance shows the transit time bacteria of the large bowel. Our experience is measured by the SLZ/P method to be longer that the transit times measured by the L/BH than that measured by the LIBH method (P < method are shorter than those measured by the 0.001). Furthermore when lactulose and sulpha- SLZ/SP methods even though it has been demon- salazine are co-administered, the transit times strated that both methods measure the time of are similar to each other, and to those found with arrival of the test meal head at the caecum lactulose alone. Our results suggest that lactulose (Kellow et al., 1986). We undertook the follow- reduces the transit time, a finding consistent with ing experiment to investigate this. the observations of Bond & Levitt (1972). The Fifteen subjects took part in a double blind SLZ/SP method is not believed to affect the randomised three-part cross-over study to com- transit time measured and may give a more valid pare the oro-caecal transit time assessed using measure of oro-caecal transit time. the L/BH or the SLZ/SP methods when 20 ml

Table 1 Oro-caecal transit times assessed by the L/BH or SLZ/SP methods when lactulose and sulphasalazine were given alone and together Method ofassessing oro-caecal Test material Oro-caecal transit transit time given time (h ± s.d.) Lactulose/breath hydrogen L 2.23 ± 0.54 L+S 2.55 ± 0.61 Sulphasalazine/sulphapyridine L+S 2.18 ± 0.52 S 5.03 ± 0.93 L = lactulose given alone, S = sulphasalazine given alone, + = coadmin- istration

Bond, J. H. & Levitt, M. D. J. (1972). Clin. Invest., Kellow, J. E. et al. (1986). Gastroenterology, 91, 396. 51, 1219. Proceedings ofthe BPS, 9-11 September 1987 131P

Effect in man of aspirin, standard into timed gastric aspirates was determined in 20 indomethacin, and sustained release healthy volunteers after receiving, over 96 h preparations on gastric micro-bleeding either placebo, aspirin (600 mg four times daily; 17 doses), indomethacin BP (50 mg three times P. J. PRICHARD, T. J. PONIATOWSKA, daily; 13 doses), Indocid-R (75 mg twice daily; 9 J. E. WILLARS & C. J. HAWKEY doses) or indomethacin Continus (75 mg twice Department of Therapeutics, University Hospital, daily; 9 doses). A venous blood sample was also Nottingham NG7 2UH taken during each treatment period for subse- quent determination of a1-glycoprotein. Blood The majority of reported adverse drug reactions loss was determined by haemoglobin assay for NSAIDs are for dyspepsia, peptic ulceration (hydrogen peroxide/orthotolidine method) and and its complications. Indomethacin (excluding corrected for phenol red recovery. Osmosin) is ranked third behind piroxicam and Gastric micro-bleeding on placebo was 1.4 naproxen in the number of reports of serious (0.7-2.8) ,ul 10 min-' (mean, 95% confidence gastrointestinal adverse reactions from 1964 interval). Both aspirin and the indomethacin to 1985. There is also growing evidence that preparations caused significantly more bleeding NSAIDs, particularly indomethacin, may injure (P < 0.01). Rates of micro-bleeding after aspirin, the small intestine in animals. In animal studies indomethacin BP, Indocid-R, and indomethacin levels of acute phase protein, ac-glycoprotein, Continus were respectively 22.0 (10.7-47.2) ,ul appear to correlate with the extent of indo- 10 min-', 4.4 (2.2-9.1) ILI 10 min-1, 10.8 (5.3- methacin-induced intestinal damage (Billingham 22.3) pI lOmin-' and 5.1(3.0-10.6) pR1 lOmin1. & Tucker, 1979). Rates of micro-bleeding after indomethacin BP A way of improving the tolerance or reducing and indomethacin Continus, but not Indocid-R, mucosal toxicity of indomethacin may be con- were significantly less than after aspirin (P < trolled release preparations. We have compared 0.05). a1-glycoprotein levels were not signifi- the effect on gastric microbleeding of a new cantly affected by prior treatment with aspirin or controlled release preparation, indomethacin indomethacin. Continus, with that of aspirin and other indo- In this study we have been able to discriminate methacin preparations in man. ao-glycoprotein between the gastric mucosal toxicity of different levels were also measured to examine whether NSAID preparations. Indomethacin Continus, this might be a useful index of intestinal injury in appeared to have less gastric toxicity than aspirin man. The study was approved by the University whereas the other sustained release preparation, Medical Ethics Committee. Indocid-R was not significantly different from In a randomized crossover study blood loss aspirin.

Billingham, M. E. J. & Tucker, M. J. (1979). Br. J. Pharmac., 67, 450P.

Gastric mucosal bleeding caused by aspirin We have therefore investigated the effect of 75 mg but not low dose warfarin in human these strategies on bleeding from the gastric subjects mucosa in humans. This study was approved by the University Ethics Committee. P. J. PRICHARD, G. KITCHINGMAN & Twenty male medical students (aged 19-22 C. J. HAWKEY years) were randomised to receive each of the Department of Therapeutics, University Hospital, following treatment schedules: (a) aspirin 75 mg Nottingham NG7 2UH day-l, (b) warfarin sufficient to raise the pro- thrombin ratio to 1.4-1.6 (c) these doses of Low doses of aspirin are under investigation for aspirin and warfarin together, (d) aspirin 2.4 g the prophylaxis ofvascular disease. Factor VII is day-1. Warfarin dosing was initially at 2 mg also a risk factor for vascular disease and its day-' and adjusted according to the prothrombin reduction by low dose warfarin has been suggested ratio measured every 2 or 3 days. The subjects as supplementary prophylaxis (Mead et al., 1986). were studied under baseline conditions and after 132P Proceedings of the BPS, 9-11 September 1987 5 and 12 days (or when prothrombin ratio was day-' (no aspirin) and 4.0 (3.4-4.7) mg day-' stable between 1.4 and 1.6) on each regimen. (with concurrent aspirin). There were no signifi- Bleeding into gastric washings obtained via an cant adverse effects. orogastric tube was quantified by the orthotolidine Thus aspirin in 75 mg day-' increased bleeding reaction and corrected for phenol red recovery 1.9 (1.3-1.8)-fold (P < 0.001). Warfarin had (Hawkey et al., 1986). no significant effect either alone or in combina- One subject was removed from the study tion with aspirin. because of erratic attendance. In the others it Low dose aspirin is not without effect on took a mean of 11 days (95% confidence limits human gastric mucosa, causing detectable in- 9-13 days) to achieve a stable prothrombin ratio creases in bleeding. Warfarin itself has no effect of 1.3-1.8 and 16 (14-17) days to achieve the and did not enhance aspirin-induced bleeding ratio of 1.4-1.6 required for final study. The and appears to be a safe addition to low dose dose of warfarin required was 4.0 (3.4-4.6) mg aspirin regimens.

Table 1 Rates of bleeding (p.1 blood 10 min-', geometric mean + 95% confidence limits) Length of treatment S days 12 days* Baseline 0.61 (0.36-1.03) Warfarin 0.58 (0.31-1.06) 0.57 (0.35-0.95) Aspirin 75 mg 1.26 (0.71-2.24) 1.30 (0.59-2.89) Warfarin + aspirin 1.30 (0.59-2.89) 1.10 (0.57-2.11) Aspirin 2.4 g 8.47 (5.43-13.9) * or until stable prothrombin ratio 1.4-1.6 reached

Hawkey, C. J. et al. (1986). Am. J. Med., 81(2A), 50. Meade, T. W. et al. (1986). Lancet, ii, 533.

The influence of haematocrit on blood 1986). The reluctance of some centres to adopt cyclosporin measurements in vivo this matrix may be due to reports that the cor- relation between whole blood and plasma CSP is A. JOHNSTON1, J. T. MARSDEN2 & D. W. HOLT3 poor (Vine et al., 1986) and to the recurring 'Clinical Pharmacology, St Bartholomew's Hospital, assertion that whole blood, but not plasma or 2Renal Unit, Dulwich Hospital and 3Poisons Unit, serum, measurements are greatly influenced by Guy's Hospital, London sample haematocrit (Rosano, 1985; Zaghloul et al., 1987). In this study we have examined both The therapeutic index of the immunosuppressive postulates in 21 patients receiving CSP following drug cyclosporin (CSP) is low and, therefore, its renal transplantation. therapeutic action needs to be carefully balanced Aliquots ofwell mixed, pre-dose, EDTA anti- against its major adverse effect, nephrotoxicity. coagulated blood samples collected for routine Following renal transplantation this is difficult CSP monitoring were used for the whole blood since the clinical signs of graft rejection and measurements. Plasma was separated by centri- nephrotoxicity may be very similar; it is for this fugation after the blood had been re-equilibrated reason that routine CSP concentration monitor- to 370 C for 10 min. The Sandoz radioimmuno- ing is advocated. However, establishing a refer- assay kit (polyclonal, polyvalent, antibody) was ence range for the drug in plasma which can be used for the drug measurements and only results applied by all centres has been complicated by which fell within the calibration range (62-2000 the variable, temperature dependent, partition- ,ug 11) were used. ing of the drug between plasma and erythrocytes. There were a total of 276 paired blood and As a result, the majority of laboratories in the plasma samples from the 21 patients with a median UK and Europe have chosen whole blood as the of 11 samples per patient (range 6-24). The matrix for CSP measurement (Johnston et al., maximum and minimum CSP concentrations Proceedings of the BPS, 9-11 September 1987 133P were 180 and 1898 jig I-1 for blood and 64 and CSP of 0.40 (0.34 to 0.47) while the slopes for 1068 ,ug I-1 for plasma. The packed cell volume blood and plasma CSP vs haematocrit were of of the samples ranged from 15.7 to 44.4%. -4.5 (-17.6 to 8.6) and -5.0 (-9.4 to -0.6), The correlation between blood and plasma respectively. CSP was very highly significant, r2 = 0.76. How- Thus, our data, relating to renal transplant ever, neither blood nor plasma CSP were signifi- patients, suggest that blood and plasma CSP are cantly correlated with haematocrit, r2 = 3 x 10-5 well correlated but that measurements of CSP (blood) and 5 x 10-3 (plasma). Linear regression in blood are no more influenced by sample of the data from each patient gave a mean (95% haematocrit than CSP measurements made in confidence interval) slope for blood vs plasma plasma.

Johnston, A. et al. (1986). Ther. Drug Monit., 8, 200. Vine, W. et al. (1986). Clin. Chem., 32, 1828. Rosano, T. G. (1985). Clin. Chem., 31, 410. Zaghloul, T. et al. (1987). J. clin. Pharmac., 27, 240.

Age and morphine pharmacokinetics after and nine elderly (community based), E (age 68- intravenous, oral and slow release morphine 90 years, weight 54.2-76.6 kg). The study was sulphate double-blind, double dummy and randomisd. After overnight fasting, the volunteers received S. P. BAILLIE*, K. QUINN', D. N. BATEMAN & 10 mg morphine sulphate, either as an intra- K. W. WOODHOUSE venous infusion, or an oral solution or an oral Department of Geriatric Pharmacology, Wolfson slow release tablet. Unit, University of Newcastle upon Tyne, Newcastle After intravenous morphine, the elderly had upon Tyne NE1 7RU and 'Napp Laboratories Ltd, significantly decreased clearance (CLE = 0.72 ± Cambridge Science Park, Milton Road, Cambridge 0.11 min-', CLy = 1.55 ± 0.24 1 min-1, P < CB4 4BH 0.001), but similar Vd (VdE = 5.2 ± 0.9 1 kg-', Vdy = 7.3 ± 1.51 kg-'). Both oral preparations Morphine is a narcotic analgesic frequently used produced a significantly larger AUC and Cmax in in patients with chronic pain, many of whom are the elderly (Table 1). Furthermore the time to elderly, yet age-related effects on morphine reach Cmax was longer in the elderly but this was pharmacokinetics have not been studied in depth. not statistically significant. Our results are con- We present the results of a study investigating sistent with an age-related decline in plasma the effects of age on morphine pharmacokinetics. clearance after intravenous morphine, and a Seventeen healthy volunteers were studied, reduction in first-pass metabolism after oral each on three occasions at least 1 week apart. morphine sulphate solution. There was no There were eight young (medically qualified evidence that the elderly absorbed the slow re- staff), Y (age 26-30 years, weight 42.5-83.3 kg) lease formulation more slowly than the young.

Table 1 Mean ± s.e. mean results Oral solution Slow release tablet Young Elderly Young Elderly n=8 n=9 n=8 n=9 Cmax (L9g 1') 10.8 ± 1.4* 20.5 ± 3.8* 5.0 ± 0.3* 8.0 ± 1.1* tmax (h) 0.6 + 0.2 0.5 ± 0.1 1.8 + 0.4 2.6 ± 0.4 t½ (h) 2.2 ± 0.7 2.6 ± 0.6 AUC (pg 1'- h) 22.9 2.8t 47.8 9.1t 25.9 3.3t 43.8 5.3t Bioavailability (%) 20.1 ± 3.0 29.3 ± 4.4 22.9 ± 2.9 28.7 ± 3.6 *P<0.5YvsE;tP<0.OlYvsE 134P Proceedings of the BPS, 9-11 September 1987

Caffeine reduces the clearance oftheophylline phylline was used with a coefficient of variation in the presence of a normal dietary methyl of < 5% at 5.4 mg -1'. Pharmacokinetic analysis xanthine intake was performed using non linear regression analysis fitting data to a one compartment oral S. H. D. JACKSON, A. JOHNSTON & K. SHAH dosing model. Pharmacokinetic parameters Department of Clincial Pharmacology, St Bartholo- were compared using Student's paired t-test. mew's Hospital, London EClA 7BE Where a significant change in a parameter occurred (e.g. clearance), simultaneous fitting There have been no previous studies of the of the concentration-time data obtained from changes in serum pharmacokinetics of theo- each subject on both study days was performed phylline induced by caffeine. Several previous with an additional parameter included in the studies have employed urine sampling after i.v. model representing the proportional change in radiolabelled theophylline. These studies have clearance induced by caffeine (Pc). shown an increased clearance of theophylline There was a statistically significant fall in theo- during a methyl xanthine exclusion diet (Caldwell phylline clearance of 26.4 ± 16.4 ml min-1 et al., 1977) which could be reversed by supple- (mean ± s.d.) (t = 3.94, 1P < 0.006) and rise in ments of caffeine and theophylline (Monks et theophylline tv½ of 2.4 ± 1.8 h (t = 3.3, 1P < al., 1979) and no change in clearance during 0.02) induced by caffeine. The other parameters modest caffeine supplementation of a normal did not change significantly. When simultaneous diet (Monks et al., 1981). Paired data from only fitting was performed assuming fixed (best fit) three subjects were reported in these studies. values for ka, tlag and Vd on the 2 study days, the We administered 400 mg of theophylline alone mean Pc value was 0.73 representing a 27% fall and in combination with 400 mg of caffeine, in clearance of caffeine. using a balanced double-blind trial design, to six The likely mechanism of this effect is saturation healthy volunteers. Blood was taken for serum of the forms of cytochrome P450 responsible for theophylline assay 11 times over the next 8 h. hepatic metabolism of theophylline. An enzyme mediated immunoassay for theo-

Caldwell, J. et al. (1977). Br. J. clin. Pharmac., 4, Monks, T. J. et al. (1981). Biopharm. Drug Disp., 2, 637P. 31. Monks, T. J. et al. (1979). Clin. Pharmac. Ther., 26, 513.

Pharmacokinetics ofchlorpromazine (CPZ) and chlorimipramine (CI) in healthy capacity have been reported to be quite similar volunteers in humans. Furthermore, studies on the pharma- cological behaviour of the two drugs at their G. P. SGARAGLI, R. NINCI, L. DELLA CORTE, respective cellular target sites so far identified in M. VALOTI & M. PALMI the rat brain, have provided the evidence that Centro Interdipartimentale di Ricerca sul Metabolismo CPZ is effective at concentrations much lower dei Farmaci Psicotropi-Instituto di Scienze Farmaco- than those required for the action of CI. To logiche, Universita di Siena, and Dipartimento di investigate the possibility that a difference in the Farmacologia Preclinica e Clinica 'M. Aiazzi Mancini' disposition rate and the kinetic behaviour of Universith di Firenze, Italy CPZ and CI in man might explain the difference in their clinical dosage, the pharmacokinetics of The antipsychotic drug CPZ shares a striking CPZ and CI were compared in a population of structural similarity with CI, an antidepressant nine male and nine female healthy volunteers compound largely used in western countries. (age 21-40 years). Plasma concentrations of In spite of this similarity, the clinical usage of parent drugs and their NOR1- and NOR2- CI and CPZ is characterized by remarkably derivatives were measured up to 24 h following a different oral daily dosages, being about 200 mg single oral dose of 0.7 mg kg-' body weight of for CI and up to 1,500 mg for CPZ. This is rather CPZ and CI given to each subject on separate surprising since their oral bioavailability, their occasions, by a GC method using nitrogen phos- lipophilicity and their plasma protein binding phorus selective detection (Ninci et al., 1986). Proceedings of the BPS, 9-11 September 1987 135P Ingestion of CI resulted in a four fold higher suggesting a genetic polymorphism in one of the area under the sum of parent drug/metabolite enzyme activities controlling the biotransforma- plasma concentration curve (AUCoG24) than that tion of this drug. The absence of such behaviour observed in the same subjects following CPZ following CI treatment suggests that, in spite of intake, 583 ± 120 and 138 ± 28 ng ml-' h their structural similarities, CI and CPZ are respectively. CI, however, showed a slower metabolized in the same individuals by different apparent absorption rate than CPZ, reaching enzyme systems. The recent observation that plasma peak levels about 2 h later. Elimination CPZ was extensively dechlorinated in chronically rate limited kinetics were observed for CI NOR- treated schizophrenics (Sgaragli et al., 1986) metabolites, whereas CPZ NOR-metabolite whereas dechlorination of CI was undetectable kinetics appeared to be formation rate limited. in chronically treated depressed patients (un- The apparent elimination half-life and the N- published observation) emphasizes the existence demethylation ratio of CPZ were not correlated; of differences in the metabolic fate of these two however, both these parameters appeared to be drugs. bimodally distributed (slow (10.2 ± 1.5 h) and rapid (2.5 ± 0.3 h) t½ elimination and slow (0.21 This work was supported by M.P.I. and C.N.R., Roma, + 0.04) and rapid (3.45 ± 2.5) N-demethylation), Italy. Ninci, R. et al. (1986). J. Chromatogr., 381, 315. Sgaragli, G. P. etal. (1986). Drug. Metab. Dispos., 14, 263.

Pharmacodynamic effects of single and Both treatments had the expected depressant repeated doses of two formulations of effects on c.f.f.f. and manual dexterity. Plasma trazodone concentrations of trazodone indicated that steady state had been reached by day 2 of repeated S. I. ANKIER, Q. A. MEKKI & S. J. WARRINGTON dosing. There was a trend towards shorter dura- Charterhouse Clinical Research Unit, London tion of action of the depressant effect of trazo- ECIM 6HR done on c.f.f.f. and manual dexterity on day 7 for both treatments. The data were subjected to In a double-blind study, pharmacodynamic effects analysis of variance. of single and repeated doses of two formulations For manual dexterity, analysis of variance oftrazodone were compared in 12 healthy young showed a significant difference between treat- volunteers (six men and six women). They re- ments (P < 0.001): for the controlled release ceived either trazodone 100 mg conventional tablet, manual dexterity performance was better capsules (Molipaxin) or 150 mg controlled release on day 7 than on day 1 at all times after dosing, tablets daily at 08.00 h for two 7 day periods whereas for the conventional capsule manual separated by a 'washout' period of 1 week. dexterity was worse on day 7 than on day 1 until Blood pressure (BP) standing and lying, critical 4 h and 8 h after dosing, when performance was flicker fusion frequency (c.f.f.f.) and manual better than on day 1. dexterity were measured on days 1 and 7 of each In this study, both formulations of trazodone session before and at intervals up to 8 h after the caused the expected negative effects on psycho- dose. Manual dexterity was tested by measuring motor function. Further studies would be required the time taken to drop 50 airgun pellets down a to confirm the apparent advantage of the con- narrow tube. A daily pre-dose blood sample was trolled release tablet in the test of manual dex- also taken for measurement of trazodone to terity. check compliance and to confirm that steady state had been achieved. 136P Proceedings of the BPS, 9-11 September 1987

Table 1 Manual dexterity (mean number pellets/min) Conventional trazodone Controlled release trazodone Time (h) Day 1 Day 7 Day I Day 7 0 29.9 29.6 28.9 30.2 1 27.5 26.7 27.2 28.0 2 27.7 27.2 26.5 28.6 4 27.4 30.2 27.3 29.3 8 28.7 30.4 27.7 30.7

A specific h.p.l.c. method for the deter- were shaken mechanically for 30 min and then mination of BRL 43694 in plasma and urine centrifuged to separate the layers. The upper organic layer was transferred to silanised vials A. CLARKSON, P. E. COATES & B. D. ZUSSMAN and evaporated to dryness at 600 C using a gentle (introduced by C. M. Kaye) stream of nitrogen. Residues were reconstituted Drug Metabolism and Pharmacokinetics Department, in 100 pl ofh.p.l.c. mobile phase and transferred Beecham Pharmaceuticals Research Division, Harlow, to autoinjector vials, from which 80 pl were Essex CM19 5AD injected onto the column. Chromatographic separation was achieved on a 25 cm x 4.5 mm BRL 43694, endo-N-(9-methyl-9-azabicyclo Apex CN 10 pum column protected by a 5 cm [3,3, 1]non-3-yl)-1-methyl-indazole-3-carbox- guard column. The mobile phase was delivered amide, is a novel 5-HT3 receptor antagonist at 1.0 ml min-1. It was 3% (v/v) 0.05 M sodium which, in ferrets, is known to abolish emesis acetate buffer adjusted to pH 6.0 after the addi- evoked by cisplatin, other cytotoxic drugs or by tion of0.25% triethylamine, and 97% methanol. X-irradiation (Boyle et al., 1987). In order to Wavelengths for detection were 305 nm (excita- monitor the plasma concentrations and urinary tion) and 360 nm (emission). The absolute reten- excretion of BRL 43694 during preclinical and tion times of BRL 43694 and BRL 43704 were clinical evaluation, a simple, sensitive and repro- 13.5 and 19.2 min, respectively. ducible h.p.l.c. assay with fluorimetric detection With this procedure, the limit of reliable deter- was developed. The internal standard, BRL mination for BRL 43694 is about 0.1 ng ml-'. 43704, is an analogue of BRL 43694. Both com- Calibration graphs for BRL 43694 are linear up pounds exhibit intense native fluorescence and to at least 100 ng extracted. Reproducibility and are detected directly. accuracy are generally better than 10% and the To each plasma or urine sample (1 ml) in a robustness of the method has been established in silanised vial was added an aqueous solution of extended use. The method is applicable to plasma internal standard (100 ,ul), 0.1 MpH 12 phosphate and urine samples from rat, dog and man. buffer (0.5 ml) and toluene (3.0 ml). The samples

Boyle, E. A. et al. (1987). Br. J. Pharmac., 91, 418P.

The pharmacokinetics of cromakalim, Cromakalim, BRL 34915, (± )6-cyano-3,4- BRL 34915, a new antihypertensive agent, dihydro-2,2-dimethyl-trans-4-(2-oxo-1-pyrroli- in healthy male subjects dinyl)-2H-benzo[b]-pyran-3-ol, is a novel orally active antihypertensive agent which acts via B. E. DAVIES', D. DIERDORF, K. M. ECKL, potassium channel activation. W. H. GREB, G. MELLOWS1 & T. THOMSEN The reduction in blood pressure seen in hyper- (introduced by C. M. Kaye) tensive patients suggests that cromakalim may Beecham-Wulfing GmbH and Co. KG, Clinical Re- be suitable for administration on a once daily search Unit, 4040 Neuss 1, FRG and 'Beecham dosing regimen. Pharmaceuticals, Research Division, Medicinal Re- Following single oral administration of search Centre, Harlow, Essex CM19 5AD cromakalim to different healthy male subjects Proceedings of the BPS, 9-11 September 1987 137P at dose levels of 0.5, 1.0, 1.5 and 2.0 mg, the lated from the day 1 data by the method ofsuper- mean maximum observed plasma concentrations position. There was no significant difference (P (Cmax) are 4.4, 8.7, 13.0 and 17.3 ng ml-', > 0.05) between the actual and predicted values respectively. indicating that cromakalim obeys linear kinetics Cromakalim was administered to five healthy on repeated administration. In addition there male subjects either in the fasted state or after a were no significant differences (P > 0.05) in standard breakfast. Although there was a slight appropriate pharmacokinetic parameters between delay in the time to Cmax, the relative bioavail- single dose and repeat dose administration. The ability assessed from AUC values was unchanged. mean Cm:, terminal half-life, AUC, apparent The differences in the corresponding pharmaco- oral clearance (CL/F), and mean residence time kinetic parameters were not statistically significant (MRT) were 9.3 ng ml-l, 22.5 h, 297 ng ml-1 h, (P> 0.05). 57.0 ml min-1 and 36.0, respectively, after single Cromakalim was administered to 12 healthy oral administration. The apparent oral clearance male subjects, initially as a single dose followed was consistent with a low extraction drug. 5 days later by repeated daily dosing for 28 days. Overall, the results of these studies indicate Analysis of plasma samples by capillary GC that there is little inter- and intra-individual (Davies, 1987) has shown that the Cmax of variation in the pharmacokinetics of cromakalim cromakalim occurred 2 to 6 h post-dose. Peak following its oral administration, and they sup- and trough concentrations on day 28 were calcu- port a convenient once daily dosing regimen.

Davies, B. E. (1987). Br. J. clin. Pharmac., 24, 237P.

Platinum concentration in tumours of the tion spectrometry. Plasma was diluted with 0.5% head and neck after intravenous cisplatin Triton X-100 and the Pt concentration measured infusion by standard additions. Results from plasma showed that the concen- J. D. HOLDING, W. E. LINDUP, tration of total Pt fell rapidly over the first few D. A. BOWDLER1, J. CAMPBELL1, hours post-infusion and then more slowly, as has M. Z. SIODLAK' & P. M. STELL' been found by others (Gormley et al., 1979; Department of Pharmacology and Therapeutics, Himmelstein et al., 1981). Platinum was much University of Liverpool, P.O. Box 147, Liverpool more persistent in the tumour however and L69 3BX and 'University Department of Otorhino- appeared to be at or near its maximum at the end laryngology, Royal Liverpool Hospital, Prescot Street, of the infusion (Table 1), and fell only slowly Liverpool over the next 48 h. In two patients further tumour biopsies were Cisplatin is an effective drug for the treatment of taken 1 month after treatment and Pt was still many forms of cancer, and is one of the few detectable. We have so far found no correlation drugs found to be effective against cancers of the between the dose of cisplatin and the Pt concen- head and neck (Kish et al., 1985). There have tration in the tumour, but survival times were been many studies of cisplatin in vitro, but as yet increased if a higher tumour concentration of there is little information available on the con- Pt was achieved. The median survival time of centration that is achieved in the tumour itself patients with greater than 3 jig g-1 wet wt of Pt at and so we have looked at this aspect of head and the end of infusion was 6.5 months compared neck tumours in relation to survival of the patient. with 2 months for patients with lower concentra- Twelve patients with end-stage head and neck tions. malignancies of squamous cell origin who had In conclusion we have shown that after an 8 h had no previous chemotherapy received an 8 h infusion of cisplatin, head and neck tumours i.v. infusion of cisplatin at either full dose (100 contain about 4 ,ug Pt g-' wet wt and that a mg m2) or half dose (50 mg m 2) depending on higher tumour concentration was associated their renal function prior to treatment. Tumour with longer survival. biopsies and plasma samples were taken at the end of the infusion and 24 and 48 h later. Biopsies We thank the North West Cancer Research Fund for were digested in nitric acid and then analysed for financial support. platinum (Pt) content by flameless atomic absorp- 138P Proceedings ofthe BPS, 9-11 September 1987 Table 1 Tumour and plasma concentrations of platinum after i.v. infusion Time post-infusion Tumour Plasma (h) (,ug Ptg-' tissue) (,ug ml-,) 0 3.7 ± 1.4 2.5 ± 0.9 24 3.7± 1.5 1.6±0.6 41-64 0.8-4.3* 0.6-1.9* Mean ± s.d., except * range, n = 9

Gormley, P. E. etal. (1979). Clin. Pharmac. Ther., 25, Kish, J. A. et al. (1985). Cancer, 56, 2740. 351. Himmelstein, K. J. etal. (1981). Clin. Pharmac. Ther., 29, 658.

An audit of digoxin serum concentration service, i.e. 1978, were compared with requests monitoring during a similar period for 1986. They were scrutinised for their documentation and were G. P. MOULD & V. MARKS designated adequate if the digoxin dose was Clinical Pharmacokinetic Unit and Department of recorded, its timing and sampling time noted Clinical Biochemistry & Nutrition, St Luke's Hospital, and reason for the request documented. Guildford, Surrey GUl 3NT In 1978, there was a total of 991 requests from 696 patients and in 1986, 1108 requests from 844 Digoxin, widely used for the treatment of con- patients. Documentation details were taken gestive cardiac failure and for the control of from two similar consecutive 9 month periods cardiac arrhythmias, is a useful drug to measure and are shown in Table 1. in certain patients, because of its low therapeutic It can be seen that there is an improvement in ratio. However, the long-standing problem of documentation over the 8 year period (X2 = inaccurate documentation of requests, has been 25.5, P < 0.001). The timing of some requests highlighted in recent studies by Clague et al. for digoxin measurement was at the incorrect (1983) and Baillie & Angaron (1986). They found time, so that 71% of the requests contained suf- that between 17.5% and 13% only of requests ficient, correct documentation to make a mean- were appropriate, and this has led to doubts con- ingful interpretation and analysis of the results. cerning the usefulness of therapeutic drug This is compared with only 29% in 1978. monitoring (TDM) for digoxin (Gibb et al., The amount of adequate documentation in 1986). We would like to report on our experience 1986 for requests for digoxin serum measure- where there is a marked improvement in docu- ments in our hands is greater than that of other mentation through the interaction of pharmacists studies, which in fact is similar to that found by and clinical biochemists. us in 1978. This illustrates that the presence of a A TDM service has been supervised by a pharmacist and provision of a TDM service leads pharmacist, based in the biochemistry depart- eventually to better documentation. This has ment since 1978. Details of the digoxin requests important considerations for the cost benefit received during a period of the initial year of the analysis of drug assay requests.

Table 1 Details of digoxin requests (number of details supplied) Reasonfor Dose of Year Sample size Timing request drug 1986 509 436 415 454 1978 490 132 391 386 Proceedings of the BPS, 9-11 September 1987 139P

Baillie, G. R. & Angaran, D. M. (1986). Pharm. J., Gibb, I. et al. (1986). Br. med. J., 293, 678. 236, 392. Clague, H. W. et al. (1983). Ther. Drug Monitor., 5, 249.

Slow dissolution characteristics in vitro do subject (AUC(0-Mi)), apparent terminal dis- not necessarily imply slow and sustained position rate constant (k), mean residence time release behaviour in vivo (MRT), the time to reach CmaxI2 in the ascend- ing (Wa) and descending phase (Wd) of the C. de MEY, E. BRENDEL, D. ENTERLING & curve, time at concentrations > = Cmax/2 (W1/2) H. WESCHE and 48 h urinary excretion as % of dose (U48). SK&F-Institute for Applied Clinical Pharmacology, The log-transformed dose-adjusted Cmax and Hildebrandstrasse 10, D-3400 Goettingen, FRG AUC(0-i), the log-transformed K, MRT, U48 and W1/2 were assessed by ANOVA (Subjects, It is often assumed that slow dissolution charac- Sequences, Groups, Treatments, Group x teristics of oral formulations will assure a less Treatment and Group x Period). The residual prompt and more protracted input of active variance was used to calculate the 95% CI around compound into the systemic circulation, result- the geometric mean of the individual parameter ing in lower Cmax values whilst plasma concen- ratios for T:R. trations remain longer within a desired range. The test formulation had a reduced systemic The present study assessed whether a formulation bioavailability and the mean Cmax was reduced with delayed in vitro dissolution of cimetidine only slightly more than expected on this basis. would allow such slow and sustained release The mean MRT after T, was longer but was behaviour in vivo to be obtained. affected by bias relating to the far larger extra- Twelve normal subjects were studied on two polations required for its calculation due to the occasions, at least 1 week apart, in two groups of flatter slopes used for them. The longer MRT six subjects. Either a standard 400 mg Tagamet merely reflected the global shift of the curves tablet (R) was given or an investigational formu- with a slower ascending slope (median Wa: 20 lation of 350 mg cimetidine (T). One hundred min for R, and 144 for T) but a rather similar per cent in vitro dissolution occurred in water descending slope. The median tmax for T (270 within 15 min for treatment R, and 57%, 84% min) was longer than for R (60 min), mainly and 95% after 1, 2 and 3 h, for treatment T. because of the disappearance of the first (and Treatments were allocated in balanced cross- highest) of the two peaks of the plasma concen- over design. Blood samples were drawn up to trations seen after R. Rather than truly reflect- 24 h post-dosing and urine was collected in ing slow and sustained release behaviour in vivo pooled fractions, from 0-24 and 24-48 h post- (indeed not supported by the similarity of Wl/ dosing. Concentrations of cimetidine were 2), these changes might reflect the narrowness of assayed by reversed h.p.l.c. The following para- cimetidine's absorption window(s) and 2) the meters were derived: Cmax, tmax, AUC extra- reduced net effectiveness of these window(s) as polated to infinity (AUC(0-oo)), AUC up to the a consequence of the delayed dissolution in per- last timepoint when plasma concentrations could spective of the gastrointestinal transit time. be quantified for both treatments in the same

Table 1 The treatment means for Reference (R) and Test (T) and the geometric mean of the individual ratios for T:R plus the surrounding 95% CI Parameter R T T:R 95% CI Cmax (,ug ml 1) 1.83 1.16 0.61 0.40 to 0.92 AUC(0-oo), (,ug ml-' h) 6.87 5.67 0.81 0.69 to 0.94 AUC(0-Mi), (,ug ml-' h) 6.67 4.94 0.71 0.59 to 0.84 U48, % 54 42 0.75 0.63 to0.90 k (h-1) 0.229 0.138 0.54 0.38 to 0.78 MRT (h) 4.45 10.05 2.11 1.67 to 2.66 W1/2 (min) 203 184 0.99 0.68 to 1.44 140P Proceedings ofthe BPS, 9-11 September 1987

Single induction doses of thiopentone, performance liquid chromatography (Prescott et propofol and midazolam do not cause al., 1979). After an interval of 3-4 weeks the enzyme induction in man subjects received propofol 2.5 mg kg-' by in- fusion over 30 min. Vital signs and level of J. P. H. FEE, G. FURNESS, J. S. C. McCOLLUM, sedation were monitored closely until the return P. S. COLLIER' & J. W. DUNDEE of consciousness. Three days later the antipyrine Departments of Anaesthetics and 'Pharmacy, The test was repeated and salivary samples collected Queen's University of Belfast, Belfast as before. Four months later the study was re- peated using midazolam 0.3 mg kg-' by infusion Previous studies have shown that a single induc- at a rate of 1 mg min-. Antipyrine half-life (t½ z) tion dose of thiopentone does not increase and clearance were calculated from the elimina- enzyme activity when measured by antipyrine tion rate constant derived from least squares elimination (Fee & Dundee, 1986). The enzyme- regression analysis of salivary antipyrine con- inducing potentials of single induction doses of centrations. The volume of distribution was based midazolam and the new anaesthetic induction on total body water (60% of body weight in kg). agent, propofol, have now also been evaluated The findings of the initial study with thiopentone in volunteers and are here reported. (5 mg kg-') already reported are included for The study was approved by the University companson. Research Ethical Committee. Three groups of Table 1 shows that mean values for clearance six fasting, healthy, staff volunteers (7M, 3F), and elimination half-life of antipyrine did not aged 29-40 years and not receiving any medica- alter significantly after either propofol, mida- tion, were given antipyrine 15 mg kg-' by mouth zolam or thiopentone. These results indicate in an orange drink (100 ml). Samples of saliva that in the absence of operation, none of these were collected before antipyrine dosing and after anaesthetic induction agents increase hepatic 3, 4.5, 6, 8, 10, 12 and 24 h and were stored at microsomal enzyme activity when given as a -20° C prior to antipyrine estimation using high single induction dose.

Table 1 Mean (± s.e. mean) values for antipyrine before and after propofol, midazolam and thiopentone Before After Propofol Clearance (1 h-1) 3.2 ± 0.61 3.3 ± 0.61 t½,z (h) 11.1 ± 0.94 10.5 ± 0.80 Midazolam Clearance (1 h-1) 6.1 ± 0.85 5.2 ± 0.66 t½,z(h) 8.1±0.58 9.3 ±0.68 Thiopentone Clearance (1 h-') 2.4 ± 0.13 2.6 ± 0.23 t½,z (h) 11.4 ± 1.23 10.6 ± 1.11

Fee, J. P. H. & Dundee, J. W. (1986). Br. J. clin. Prescott, L. F. etal. (1979). Proc. Analyt. Div. Chem. Pharmac., 22, 224P. Soc., 16, 300.

Influence of quinidine on the pharmaco- Various studies have suggested that the disposi- kinetics of nortriptyline and desipramine tion of several tricyclic antidepressants is related in man to the debrisoquine oxidation phenotype (Mell- strom et al., 1981; Inaba et al., 1985). Recently, R. AYESH, S. DAWLING', B. WIDDOP', we have confirmed that this type of genetic J. R. IDLE & R. L. SMITH regulation influences the in vivo oxidative meta- Department of Pharmacology, St Mary's Hospital bolism of nortriptyline (Ayesh et al., 1986) and Medical School, London W2 1PG and 'Poisons Unit, also extends to that of desipramine (unpublished New Cross Hospital, London SE14 SER data). Proceedings of the BPS, 9-11 September 1987 141P Quinidine (Q) has been shown to be a potent 72 h after dosing. One month later all members and selective inhibitor of the in vivo oxidative in both groups were given 50 mg of quinidine and metabolism of debrisoquine (Speirs et al., 1986) re-challenged 1 h later with nortriptyline or desi- and of the oxidation of metoprolol (Leemann et pramine. The same procedure was repeated as al., 1986) whose metabolism cosegregates with described above. that of debrisoquine. It is possible therefore that Plasma levels of both compounds were the oxidative metabolism of other drugs whose measured by g.l.c. and h.p.l.c. for nortriptyline biotransformation is regulated by the debriso- and desipramine respectively. The results ob- quine gene locus may be similarly influenced by tained are summarized for nortriptyline in Table the concomitant administration of quinidine. 1. A significantly longer plasma half-life, higher We have therefore undertaken a study to evaluate AUC and lower clearance were observed after the effects of quinidine on the plasma pharma- challenge with 50 mg of quinidine (P < 0.05) in cokinetics of nortriptyline and desipramine in all cases. healthy volunteer subjects. In the case of desipramine the administration Two groups of participants who had previously of quinidine increased three fold the plasma been characterised as extensive metabolizers with clearance pharmacokinetic parameters of the respect to debrisoquine oxidation polymorphism two volunteers studied. consented to both studies A and B. In study A The results of these investigations show that (5M), each subject was given 50 mg of notripty- the concomitant administration of quinidine can line and in study B (2M) each volunteer was markedly impair the elimination of both nor- given 50 mg of desipramine. Venous blood triptyline and desipramine and this could be a samples were drawn at 0, 2, 4, 6, 8, 10, 12, 24, 48, basis for an untoward drug interaction.

Table 1 Before Q After Q mean range mean range Nortriptyline Plasma t½, (h) 14.2 (12.7-16.7) 44.7 (36-51.6) AUC (mg -1 h) 0.6 (0.33-0.79) 2.8 (1.39-3.23) Clearance (ml min-') 5.4 (3.8-9.0) 1.9 (0.8-2.6)

Ayesh, R. et al. (1986). Br. J. clin. Pharmac., 25, Mellstrom, B. (1981). Clin. Pharmac. Ther., 30, 189. 645P. Speirs, C. J. et al. (1986). Br. J. clin. Pharmac., 22, Inaba, T. et al. (1985). Drug. Metab. Disp., 13, 443. 739. Leemann, T. et al. (1986). Eur. J. clin. Pharmac., 29, 739.

Stability of the debrisoquine metabolic ratio bolism might occur during episodes of infection to immunoperturbation by influenza and (Renton et al., 1981) or following the admin- pneumococcus vaccines istration of immunomodulator agents (Manner- ing et al., 1980). R. AYESH*, G. SCADDING', J. BROSTOFF', We report here a study of the effect of both J. R. IDLE & R. L. SMITH viral and pneumococcal vaccines on the oxidative Department of Pharmacology, St Mary's Hospital metabolism of debrisoquine expressed as the Medical School, London W2 1PG and 'Department of metabolic ratio (MR) of debrisoquine (D). Immunology, Middlesex Hospital, London Two sets of investigations were performed. Firstly, five healthy, non smoking volunteers A large number of different factors are known to (4M, 1F, mean age 29 years) who were free of alter the normal state of drug biotransformation influenza for the 6 months prior to the study and in both animals and man. It has also been recog- had previously been characterized as four pheno- nized that major changes in oxidative drug meta- typically extensive metabolizers and one poor 142P Proceedings of the BPS, 9-11 September 1987 metabolizer of debrisoquine, were studied. Secondly, four healthy volunteers (mean age Each was given 0.5 ml s.c. of inactivated influenza 27 years), were each given 0.5 ml s.c. of a vaccine (MFV-Ject). Blood was drawn before polyvalent pneumococcal vaccine (Pneumovax). vaccination and at 7, 14 and 28 days thereafter All the subjects were previously phenotyped as for measurement of serum antibody titres by extensive metabolizers of debrisoquine. All using a haemoglutination inhibition assay. Each were studied as above. The correlation co- volunteer took orally a single dose of debriso- efficients for the debrisoquine metabolic ratio quine (10 mg) and urine collected for 0-8 h on for each volunteer in the group ranged between days 3, 7, 14, 21, 28 and 35 was analysed for D 0.993-0.994. and 4-OH-D. The correlation coefficients for It is concluded that the effect of both vaccines the debrisoquine metabolic ratios (D/4-OH-D) on both debrosiquine metabolism and pheno- over 35 days for each individual ranged from type is negligible. 0.993-0.996 and no change was observed in the phenotypic status of any participant.

Mannering, G. J. et al. (1980). Ann. N. Y. Acad. Sci., Renton, K. W. (1981). Semin. Perinatal., 5, 378. 350, 314.

Variable pinacidil N-oxidation: lack of and analysed by h.p.l.c. for pinacidil and its N- correlation with the debrisoquine and oxide. The results showed a wide interindividual trimethylamine oxidation polymorphisms variation in the urinary excretion of pinacidil (mean 3.39 s.d. ± 1.44, range 1.3-6.9%) and its R. AYESH, M. AL-WAIZ, A. McBURNEY', N-oxide (mean 48.9 s.d. ± 12.88, range 25.1- S. C. MITCHELL, J. R. IDLE, J. W. WARD' & 68.3%). The metabolic disposition of pinacidil R. L. SMITH was further studied as above in an entire family Department of Pharmacology, St Mary's Hospital (Al-Waiz et al., 1987) containing two propositi Medical School, London W2 1PG and 'Department of characterized by a defect for the metabolic N- Clinical Pharmacology, Groby Road Hospital, Leicester oxidation of TMA. There was no evidence of LE3 9QE defective N-oxidation of pinacidil in this family suggesting that its variable N-oxidation is inde- Pinacidil is an antihypertensive drug which pendent of the TMA N-oxidation polymorphism. is metabolized in man largely to its N-oxide Similarly, the N-oxidation of pinacidil was (McBurney et al., 1985). The extent of forma- investigated in a panel of nine subjects previously tion of this metabolite is, however, variable and characterized as poor metabolizers with respect it was considered of interest to investigate this to the debrisoquine oxidation polymorphism. variation in relation to two polymorphic oxida- With this second group there was no evidence of tion reactions, namely those of debrisoquine 4- impaired N-oxidation of pinacidil for the nine hydroxylation (Evans et al., 1980) and the N- subjects studied. The urinary excretion of pina- oxidation of trimethylamine (TMA) (Al-Waiz cidil and its N-oxide was [(mean 3.25 s.d. ± 1.6, et al., 1987). A study was therefore set up to range 2.0-6.9%), (mean 52.5 s.d. ± 10.79, range investigate a possible correlation and cosegrega- 37.8-68.3%)] respectively. tion effects between the biotransformation of It is concluded that the N-oxidation of pinacidil pinacidil and the metabolism of debrisoquine may vary at least three fold in the population and and TMA in human volunteers. that this variation is not associated with the C- For this purpose 30 healthy normotensive hydroxylation and N-oxidation polymorphisms caucasian volunteers (18M, 12F, age range 23- described for debrisoquine and trimethylamine 52 years) each took orally a single dose of pina- respectively. cidil (12.5 mg) and the urine collected for 0-24 h

Al-Waiz, M. et al. (1987). Lancet, i, 634. McBurney, A. etal. (1985). Br. J. clin. Pharmac., 19,91. Evans, D. A. P. et al. (1980). J. med. Gen., 17, 102. Proceedings of the BPS, 9-11 September 1987 143P Cytotoxicity of the quinoneimine of parison, cells were incubated with a reactive amodiaquine arylating agent, 2,4-dinitrochlorobenzene (DNCB). J. L. MAGGS & B. K. PARK After 2 h, lymphocyte viability (relative to Department of Pharmacology and Therapeutics, vehicle (methanol; 1%, v/v) control; control > University of Liverpool, Liverpool L69 3BX 95%) was unaffected by up to 100 FM AQ. AQQI (10-100 FM) showed significant but indi- Amodiaquine (AO), a 4-aminoquinoline anti- vidually variable lymphocyte toxicity (Table 1). malarial associated with liver damage and agra- With 50 FMDNCB, 2 h lymphocyte viabilities nulocytosis in man (Neftel etal., 1986), is oxidized were 94 ± 2% (NS), 84 ± 1% (P - 0.001), 92 ± to a chemically reactive, i.e. protein arylating, 3% (NS) and 81 ± 2% (P - 0.001) for cells from quinoneimine (QI) in vitro (Maggs et al., 1987). subjects 1-4, respectively. The toxicity of AQQI Since paracetamol's hepatotoxicity is attributable (10 AM) towards lymphocytes over 2 h was less to the cytotoxicity of a Ql metabolite (Tee et al., (viability 90 ± 2% vs 85 ± 1%, P 0.005) in the 1987), the cytotoxicity ofAQQI has been studied. presence of protein (HSA, 1-5 mg ml-') with Human peripheral lymphocytes (Spielberg, 1980) which AQQI can react directly. AQQI at 10 JIM and myelocytes were used as target cells. and DNCB at 50 JIM were non-toxic towards Lymphocytes were isolated from fresh hepar- myelocytes but 50 JM AQQI reduced viability inized venous blood from healthy males. Normal from 98 ± 2% to 91 ± 2% (P - 0.005). diagnostic bone marrow as6pirate was used. AQQI was shown to be toxic towards diverse Lymphocytes (circa 1 x 10 ) and myelocytes human cells, and such toxicity might be re- (0.5 x 106) in 1 ml HEPES-buffered (pH 7.4) sponsible for the adverse reactions associated medium (Spielberg, 1980) were incubated with with AQ. This could be of particular importance AQ or synthetic AQQI (Maggs et al., 1987) at in the case of activated granulocytes since they 370 C for 2 h. Cell viability (% excluding dye) readily metabolize AQ to reactive species was assessed by trypan blue exclusion. For com- (Lambert et al., 1988).

Table 1 Toxicity of AQQI towards human lymphocytes in vitro Viability (mean % ± s.d., n = 314) Subject Control 10 AM 50,uM 100 /JM 1 98 ± 1 90 ± 4* 89 ± 2** 87 ± 2 2 94 ± 1 86 ± 2** 81 ± 3 81 ± 5 3 93 ± 2 78 ± 3** 71 ± 2 67 ± 2 4 97 ± 2 64 ± 8** 75 ± 4 67 ± 3

*P - 0.005, **P < 0.001 (Student's non-paired t-test).

Lambert, C. et al. (1987). Br. J. clin. Pharmac., 25, Neftel, K. A. et al. (1986). Br. med. J., 292, 721. 143P. Spielberg, S. (1980). J. Pharmac. exp. Ther., 213, 395. Maggs, J. L. et al. (1987). Biochem. Pharmac. (in Tee, L. B. G. et al. (1987). Biochem. Pharmac., 36, press). 1041.

Formation of chemically reactive drug Drug-induced blood dyscrasia is a relatively rare metabolites by activated human adverse drug reaction but one which carries a polymorphonuclear leucocytes high mortality (Chaplin, 1986). However, little is known of the role of drug metabolism, within C. LAMBERT, J. L. MAGGS, B. K. PARK & the target cell, in such adverse reactions. N. R. KIlTERINGHAM Human polymorphonuclear leucocytes Department of Pharmacology and Therapeutics, (PMNs) activated by particulate and soluble University of Liverpool, Liverpool L69 3BX agents release reactive oxygen species and a 144P Proceedings of the BPS, 9-11 September 1987 myeloperoxidase which generates additional radiolabelled material (Table 1) (Maggs et al., oxidants (Forman & Thomas, 1986). These ox- 1983). Stable metabolites were analysed by idising agents may chemically modify exogenous h.p.l.c. compounds (Alexander et al., 1986). We have EE2, E2, MS, PC and AQ were metabolized studied the metabolism of seven drugs by acti- to chemically reactive species by activated PMNs. vated human PMNs with particular attention to Stable metabolites (e.g. hydroxylated meta- the formation of chemically reactive metabolites. bolites) ofEE2, E2, MS and AQ were also shown PMNs were isolated from fresh venous blood to be formed in the reaction and were resolved from healthy male non-smokers by standard by h.p.l.c. SB and PT were not metabolically methods (Alexander etal., 1986). Cells (5 x 106) activated. were incubated with human serum albumin In conclusion, activated human PMNs meta- (5 mg), the PMN activator phorbol myrisate bolize certain drugs to chemically reactive inter- acetate (PMA, 10 ng ml-') and radiolabelled mediates. Activation may involve hydrogen drug (10 FM, 0.25-1.44 iCi) in Dulbecco's phos- abstraction and aromatic hydroxylation by phate buffered saline (2.5 ml) containing glucose reactive oxygen species (Gutteridge, 1987). (5 mM) at 370 C for 60 min. Control incubations Therefore, drugs which contain either phenol were performed either without cells or without (Eastmond et al., 1986) or aminophenyl groups PMA. Generation of reactive metabolites was are particularly susceptible to attack. assessed by measuring the irreversibly bound

Table 1 Irreversible binding of radiolabelled material to protein in incubations of activated PMNs and HSA Drug Irreversible binding (pmol mg-'; mean ± s.d., n = 3) No cells No PMA Cells and PMA [14C]-amodiaquine (AQ) 31.2 ± 2.8 133.3 ± 37.4 362.9 ± 45.4 [3H]-oestradiol (E2) 26.5 ± 1.0 27.5 ± 3.5 215.5 ± 26.0 [3H]-paracetamol (PC) 16.0 ± 3.0 42.5 ± 2.5 183.5 ± 9.5 [3H]-ethinyloestradiol (EE2) 50.5 ± 8.0 49.0 ± 7.0 180.0 ± 28.5 [3H]-mianserin (MS) 15.5 ± 4.5 20.5 ± 11.5 135.0 ± 38.5 [3H]-sorbinil (SB) 3.5 ± 0.1 3.9 ± 0.2 3.9 ± 0.4 [14C]-phenytoin (PT) 2.0 ± 0.5 5.0 ± 0.5 3.5 ± 0.5

Alexander, M. S. et al. (1986). Biochem. Pharmac., Forman, H. J. & Thomas, M. J. (1986). Ann. Rev. 35, 3649. Physiol., 48, 669. Chaplin, S. (1966). Adv. Drug React. Ac. Pois. Rev., Gutteridge, J. M. C. (1987). Biochem. J., 243, 709. 2, 97. Maggs, J. L. et al. (1983). J. Steroid Biochem., 19, Eastmond, D. A. et al. (1986). Mol. Pharmac., 30, 1273. 674.

Propranolol concentration in blood, seminal pranolol in blood, seminal plasma and saliva plasma and saliva in man after single and after single (80 mg) and multiple (80 mg three multiple oral doses times daily for 5 days) oral doses. Six healthy volunteers were given 80 mg pro- N. T. RAOOF & R. M. PEARSON pranolol three times daily for 5 days. Blood and Department of Clinical Pharmacology, St Bartholo- saliva were obtained before giving the drug and mew's Hospital Medical College, London ECIA 7BE then samples of blood, semen and saliva were obtained 1, 2, 4 and 8 h after the first dose. The Propranolol has been shown to be a powerful same procedure was repeated on the sixth morn- inhibitor of sperm motility (Peterson & Freund, ing of treatment. All the volunteers came fasting 1973, 1975; Hong et al., 1981). It has also the and had no food for 4 h on the day on which potential application for use as a spermicide samples were obtained. Propranolol concentra- when administered per vagina (Zipper et al., tion was measured by a high performance liquid 1983). We examined the concentration of pro- chromotographic method capable of detecting Proceedings ofthe BPS, 9-11 September 1987 145P 7.4 nmol 1-1 at which concentration the coefficient plasma reached a peak 2 h after a single dose and of variation was 7.2% (Holt etal., 1984). No side 4 h after multiple doses and were 104.1 ± 26.3 effects were reported apart from one volunteer nmol I-1 and 245.2 ± 148.3 nmol I-1 after single who felt tired and could not produce one of the and multiple oral doses respectively. 8 h samples. The mean concentration of propranolol needed The maximum concentration of propranolol in vitro to inhibit sperm motility by 50% using in blood after the first dose was 129 ± 43.7 nmol the modified trans-membrane migration method I1- (mean ± s.e. mean) and was 330 + 62.2 nmol is about 300 ,umol 1-1, lower than previously 1- 1 after multiple oral doses. Both were achieved reported, but still a thousand times more than 2 h after drug administration. The mean concen- the maximum concentration reached in seminal tration of propranolol in saliva reached a maxi- plasma after therapeutic doses. According to mum level of 86.2 ± 10.6 nmol 1-1 after a single our results it is very unlikely that propranolol dose and 173.7 ± 30.6 nmol 1-1 after multiple when given in ordinary therapeutic doses will doses and again was achieved 2 h after drug affect sperm motility. administration. The concentrations in seminal

Holt, D. W. et al. (1984). In Methods for analytical Peterson, R. N. & Freund, M. (1973). Biol. Reprod., toxicology, Vol III., ed. Sunshine, I. Boca Raton, 8, 350. Florida USA: CRC Press. Peterson, R. N. & Freund, M. (1975). Biol. Reprod., Hong, C. Y. et al. (1981). Br. J. clin. Pharmac., 12, 13, 552. 751. Zipper, J. et al. (1983). Br. med. J., 287, 1245.

Use oflow-dose phenobarbitone to assess the Two female out-patients, claiming good com- compliance of patients apparently insensitive pliance, whose previous responses to warfarin to warfarin had been very poor (INR rarely > 2.0) despite prescription of doses up to 20 and 30 mg were J. R. M. HAIGH, L. RHODES, J. A. DAVIES, switched to the capsule preparation. The first B. E. ROBERTS & M. FEELY (age 57 years, history of recurrent pulmonary Clinical Pharmacology Unit, University Department embolism) had been on warfarin, latterly 30 mg, of Medicine and Department of Haematology, The for 7 years but the introduction of capsules General Infirmary, Leeds LS1 3EX containing 20 mg warfarin increased her INR to 7.5 after 3 days. She has now been stabilised A lack of response to prescribed warfarin may (INR 2.2-2.7) on only 5 mg day-' and her PB result from inherited resistance (O'Reilly et al., plasma level to dose ratios (12.4-13.1) indicate 1964), enzyme induction by concurrent drug good compliance. The second patient (age 69 therapy, or poor compliance. We have recently years; history of recurrent deep vein thrombosis) described the use of low-dose phenobarbitone had shown an inadequate response to 20 mg (PB) as an indicator of compliance (Feely et al., warfarin (INR 1.3-1.6) over 10 months. The 1987). A previous investigation suggested that capsule preparation containing 20 mg warfarin PB doses of < 7.5 mg day-' would not interact also failed to produce the desired degree of with warfarin by inducing hepatic microsomal anticoagulation and although residual tablet enzymes (Price et al., 1986). A preliminary study counts were correct her PB level to dose ratios using in-patients showed that capsules incor- (- 6.4) indicated poor compliance. porating the total daily warfarin dose (con- These studies suggest that low-dose (2 mg) PB ventional tablets) with 2 mg PB did not affect the is suitable as a marker of compliance with war- International Normalised Ratio (INR) produced farin therapy. We have shown that two apparently by conventional warfarin alone. This observation warfarin-insensitive patients had not been taking was confirmed in four well controlled out-patients their prescribed medication; the intervention (see Table 1). improved compliance in one of these patients. 146P Proceedings of the BPS, 9-11 September 1987 Table 1 INR Age Warfarin dose After - 8 weeks on Sex (years) (mg day-') Previous 6 visits capsule preparation M 62 9 2.7-3.7 3.1 ; 3.1 M 67 5 2.2-2.8 2.4 ; 2.8 F 71 3 2.3-3.3 3.2 F 76 3 2.1-2.9 2.2

Feely, M. et al. (1987). Br. J. clin. Pharmac., 24, 77. Price, D. E. et al. (1986). Br. J. clin. Pharmac., 22, O'Reilly, R. A. et al. (1964). New Engl. J. Med., 271, 744. 809.

Pharmacological response to low-dose a small increase in INR was 4 mg day-' (range warfarin in patients at high risk ofischaemic 1.5-7 mg day-'). This resulted in a mean plasma heart disease concentration ofwarfarin of 1085 ng ml-1 (range 260-4200 ng ml-1). There was a significant cor- T. W. MEADE', B. K. PARK, Y. STIRLING', relation (r = 0.56; P S 0.01) between dose and H. WILKES' & M. J. WINN log plasma concentration ofwarfarin. There was Department of Pharmacology, University of Liver- also a significant correlation between log plasma pool, P.O. Box 147, Liverpool L69 3BX and 'MRC concentration of warfarin and INR (r = 0.37; P Epidemiology and Medical Care Unit, Northwick S 0.01), but no significant correlation between Park Hospital, Harrow, Middlesex HAl 3UJ log plasma concentration of warfarin and factor VIIc (r = -0.07). In this study, there was no This study investigated the relationship between evidence of subjects with either marked sensitivity dose, plasma concentration of warfarin, and or resistance to warfarin. haemostatic response to warfarin in patients Since the target pharmacological endpoint participating in the feasibility stage trial of low was the same in each patient (INR 1.5), varia- dose warfarin in the primary prevention of tion in the plasma concentrations of warfarin at ischaemic heart disease. each dose level is likely to reflect interindividual A total of 101 male patients (age 45-64 years) variations in the disposition of warfarin. The were studied. Warfarin was given in a dose which significant difference between groups ofpatients lowered factor VIIc levels from an average of receiving different stable doses of warfarin may 125% to about 70% (INR = 1.5). Treatment reflect interindividual variation in the pharma- began at 2 mg (p.o.) daily, and was changed by codynamic response to warfarin (e.g. at a dose of steps of 0.5 mg or 1 mg until the endpoint was 4 mg, the range of plasma concentrations is 398- reached. Blood samples were then taken for the 1940 ng ml-'). Finally, these studies have shown analysis of plasma warfarin concentrations. that although this was a study of lower doses of Factor VIIc was measured by the method of warfarin than conventional treatment, plasma Brozovic et al. (1974). Plasma warfarin concen- concentrations of warfarin were similar to those trations were measured using the high perfor- seen by others after therapeutic anticoagulation mance liquid chromatographic technique of (see Holford, 1986). Shearer et al. (1983). However, this was modified (by increasing the elution time between samples) BKP is a Wellcome reader and MJW is a Ward Blen- since many of the samples contained material kinsop research fellow. that contaminated the subsequent sample. The mean dose of warfarin required to produce

Brozovic, Z. et al., (1974). Br. J. Haematol., 28, 381. Shearer, M. J. et al. (1983). Adv. Chromatogr., 21, Holford, N. H. G. (1986). Clin. Pharmacokin., 11, 243. 483. Proceedings of the BPS, 9-11 September 1987 147P A new echo-Doppler ultrasound method of 4% at an angle of 55; with a constant flow rate of cardiac output determination 41 min-' the ACVF was constant to within 8% with the angle of insonation varied between 40 B. SILKE, J. M. EVANS, S. P. VERMA, and 60. S. K. SHARMA & S. H. TAYLOR The accuracy ofthe technique was determined Departments of Cardiovascular Studies, Leeds Uni- in 17 coronary patients undergoing diagnostic versity, Leeds and Infirmary, Medical Physics, Bristol thermodilution catherisation. At rest, beteen 8 Royal Infirmary, Bristol and 10 consecutive paired estimates of flow were obtained over 15 min. The Doppler mean for 150 A new non-imaging echo-Doppler ultrasound estimates (5.27) was lower (P < 0.001) than the device (Quantascope-Vital Science) circum- thermodilution value (5.5); least squares regres- vents many of the limitations of Doppler ultra- sion suggested close agreement (y = 0.6 + 0.93x: sound estimations of cardiac output (Huntsman r = 0.91, P < 0.001). et al., 1983). The principle of attenuated com- The reproducibility (coefficient of variation pensated volume flow (ACVF) is used and con- expressed as % of mean) over 20 min when eight sists of a two parallel channel pulsed Doppler consecutive measurements were recorded at 2-3 system using concentric ultrasound beams. The min was for ischaemics (n = 12) and normals (n first is a wide beam whose sample volume totally = 10) respectively (mean ± s.e. mean: range): encompasses the vessel lumen; the second samples in the centre of the vessel. For cardiac output Cardiac output 5.3 ± 0.4 4.8 ± 0.7 applications, the aortic X-sectional area is com- (2.1-7.4) (2.8-10.1) puted from the ratio of the energy (i.e. the Stroke volume 5.1 ± 0.5 3.8 ± 0.3 power spectrum of the Doppler shift frequency) of the beams; when multiplied by the integrated (2.3-8.7) (1.9-5.2) velocity from the wide beam (estimating flow), Stroke length 6.1 ± 0.8 4.4 ± 0.4 the cardiac output is computed. (2.8-12.6) (2.5-6.4) In vitro studies validated the principle by com- Acceleration 8.7 ± 1.6 5.8 ± 1.1 paring ACVF estimates with those of a calibrated (2.3-18.7) (2.7-15.4) electromagnetic flow probe at rates up 8 1 min-1. In a 15 mm thin walled plastic tube, with citrated These data validate the accuracy and repro- human blood and haematocrit 40%, the flow ducibility of the ACVF principle; applications to was accurate to within 5% over the range 1-8 1 human pharmacodynamic studies and clinical min-'. The power ratio was constant to within assessments would appear possible.

Huntsman, L. L. et al. (1983). Circulation, 67, 593.

The effects of iloprost on calf blood flow in properties of the PGI2 analogue iloprost (ZK patients with severe peripheral arterial 36374) may exert a useful role in this situation by disease possibly improving the lower limb circulation. To investigate its effects on calf blood flow, the D. H. ROBERTS, K. LINGE', D. P. NIXON', severity of skin lesions (ulcers, cracking, blue- P. T. CHATLANI', G. A. McLOUGHLIN' & ness) and the symptoms of pain (measured on a A. M. BRECKENRIDGE visual analogue scale) iloprost was infused in an Department of Pharmacology and Therapeutics, Uni- open study for 8 h on 3 consecutive days using versity of Liverpool, P.O. Box 147, Liverpool, L69 maximum tolerated doses in five patients with 3BX and 'Royal Liverpool Hospital, Prescot Street, rest pain. Their mean age was 62.8 years (range Liverpool, L7 8XP 51-77); mean duration of rest pain 8.8 weeks (range 1-16). All had prior symptoms of inter- In advanced stages ofperipheral arterial disease, mittent claudication of mean duration 3.1 years in which vascular reconstruction or sympathec- (range 0.5-10). Smoking habits showed no signi- tomy is inappropriate or has failed, therapeutic ficant change during the study. The maximum alternatives to amputation are sought in order mean rate of iloprost infused was 3.3 ng kg-' to relieve rest pain and induce ulcer healing. min-' (range 2-5.3) with intolerable headache The vasodilator and platelet anti-aggregatory (n = 4), flushing (n = 3), gastrointestinal pain 148P Proceedings of the BPS, 9-11 September 1987 (n = 1), nausea (n = 1) and sweating (n = 1) which indirectly reflect skin blood flow (Roberts occurring above this rate. Two patients also et al., 1986; Linge et al., 1987). The results experienced an asymptomatic fall in supine dia- reflecting changes in measurements from base- stolic BP >, 30 mm Hg. line (Day 0) are shown in Table 1. Measurements were performed at rest in a No significant changes were noted in CBF, temperature constant laboratory (250 C) with TcPo2 or EHC. Skin lesions improved in two the patients supine, prior to (Day 0), during patients at Days 4 and 28. The same two patients (Day 3) and afer (Day 4, Day 28) infusion and have avoided amputation for relief of pain. These included (i) calf blood flow (CBF) by the tech- results suggest that iloprost does not improve nique of venous occlusion plethysmography; (ii) lower limb blood flow in patients with rest pain. calf transcutaneous oxygen tension (TcPo2) Larger placebo-controlled studies are needed to together with electrode heat consumption (EHC) assess any other potential benefit in such patients.

Table 1 Effects of iloprost infusions (changes in parameters from baseline) Assessment date CBF TcP02 EHC Pain (n = population) (mlJOO0ml-' min-') (mm Hg) (MW) (arbitrary units) Day 3 -0.18 ± 0.15 1.60 ± 5.78 7.00 ± 7.80 -7.00 ± 4.04 n= 5 Day 4 -0.68 ± 0.44 9.60 ± 11.05 -0.40 ± 9.57 -14.60 ± 7.28 n= 5 Day 28 0.20 ± 0.30 6.00 ± 22.00 14.50 ± 4.50 1.50 ± 10.50 n =2

Roberts, D. H. etal. (1986). Br. med. J., 293, 392. Linge, K. et al. (1987). Clin. Phys. Physiol. Meas. (in press).-

The effects of iloprost on calf blood flow in using a 5% gradient and speeds of either 2.5 or patients with stable intermittent claudication 3.5 km h-1. Exercise tests were performed on five separate occasions during the month prior to D. H. ROBERTS, K. LINGE', D. P. NIXON', infusions and the treadmill speed and gradient P. T. CHATLANI', G. A. McLOUGHLIN' & were held constant during the study month. A. M. BRECKENRIDGE Smoking habits and body weight showed no Department of Pharmacology and Therapeutics, significant change during the study. University of Liverpool, P.O. Box 147, Liverpool, Measurements were performed in a tempera- L69 3BX and 'Royal Liverpool Hospital, Prescot Street, ture constant laboratory (250 C) prior to (Day 0), Liverpool, L7 8XP during (Day 3) and after (Day 4, Day 28) infusion and included (i) claudication (CD) and total The PGI2 analogue iloprost (ZK 36374) is both a walking distances (WD); (ii) calf blood flow vasodilator and an inhibitor of platelet aggrega- (CBF) by the technique of venous occlusion tion and hence may exert a useful role in the plethysmography. Values were obtained at rest treatment of intermittent claudication not and from 2 min after exercise. 'Total excess' amenable to surgery or angioplasty by possibly CBF (ml 100 ml min-'), 2 min CBF/'total excess' improving limb blood flow. To investigate its CBF (%) and CBF recovery time (min) were effects in an open study on walking capacity and calculated after exercise (Hillestad, 1963); (iii) calf blood flow, iloprost was infused for 8 h on 3 calf transcutaneous oxygen tension (TcPo2) consecutive days using maximum tolerated dose monitored prior to, during and after exercise in five patients. All subjects had stable inter- together with electrode heat consumption mittent claudication of mean duration 38.8 (EHC) which indirectly reflect skin blood flow months (range 12-72). Their mean age was 64.3 (Roberts et a!., 1986; Linge et al., 1987). The years (range 55-80). All five developed claudi- maximum mean rate of iloprost infused was 2.8 cation within 500 m during treadmill exercise ng kg-' min-' (range 2-4) with facial flushing Proceedings ofthe BPS, 9-11 September 1987 149P (n = 5), headache (n = 4) and gastrointestinal during and after infusion. Resting and post- pain (n = 3) occurring above this rate. There was exercise CBF however showed no increase at no fall in blood pressure in any subject how- these times. There was also no significant alter- ever. The results reflecting changes in measured ation in TcPo2 and EHC. These results suggest parameters from baseline (Day 0) are shown in that iloprost does not improve the lower limb Table 1. circulation in patients with claudication. CD (P - 0.05) and WD (NS) were increased

Table 1 Effects of iloprost infusions-changes in parameters from baseline (mean ± s.e. mean) CBF CBF CBF TcPo2 EHC CBF total 2 minltotal recovery Pre-post Pre-post Assessment date CD WD Rest excess excess time exercise exercise (n = population) (m) (m) (ml 100 ml- min-') (ml 100 ml' min') (%) (mins) (mm Hg) (mW)

Day 3 65.14* 78.32 -1.00 -3.04 -0.82 0.10 -12.20 4.40 n = 5 ±18.37 ±32.47 ±0.78 ±8.72 ±1.23 ±0.78 ±5.00 ±8.20 Day 4 70.28* 87.84 -0.64 5.32 -0.56 0.30 -5.80 3.80 n = 5 ±15.81 ±29.75 ±0.54 ±9.03 ±1.00 ±0.49 ±4.41 ±7.71 Day 28 56.62* 65.08 -0.13 6.95 -0.80 0.13 -9.00 0.00 n = 4 ±14.23 ±34.66 ±0.20 ±7.32 ±1.41 ±0.43 ±7.15 ±0.11

P 0.05

Hillestad, L. K. (1963). Acta med. Scand., 174, 671. Roberts, D. H. et al. (1986). Br. med. J., 293, 392. Linge, K. et al. (1987). Clin. Phys. Physiol. Meas. (in press).

Renal haemodynamic and blood pressure end of the placebo run-in period and again after lowering effects of flosequinan 20 weeks of active treatment, we determined: (1) ambulatory BP with the Remler M 2000 A. G. DUPONT, K. DE MEIRLEIR, recorder (Dupont et al., 1987), (2) office BP and P. VAN DER NIEPEN & R. 0. SIX heart rate during exercise (bicycle ergometer), Department of Internal Medicine, AZ VUB, Univer- (3) glomerular filtration rate (GFR) as measured sity of Brussels (VUB), Brussels, Belgium from the plasma clearance of 99mTc-DTPA, (4) effective renal plasma flow (ERPF) as estimated Flosequinan, BTS 49465 (7-fluoro-1-methyl-3- from the theoretical volumes of distribution of methyl-sulphinyl-4-quinolone), is a newly de- i.v. 13I-orthoiodohippurate (Tauxe etal., 1971). veloped peripheral vasodilator with effects on RBF was calculated as ERPF/(1-haematocrit) both arterial and venous vascular beds. We and renal vascular resistance (RVR) as mean examined the effects of flosequinan on office BP BP/RBF. Results were analysed by one-way at rest and during exercise, on ambulatory BP analysis of variance and the Wilcoxon test. and on renal haemodynamics in patients with Nine patients terminated the study. One patient essential hypertension included in an open multi- dropped out because ofreversible oedema ofthe centre dose titration study. feet after 2 weeks of treatment (30 mg). Ten patients (five female, five male, aged 29- The final doses were 30 mg in one, 50 mg in 66 years) with mild to moderate hypertension one, 75 mg in two and 100 mg in five patients. (sitting diast BP between 95-114 mm Hg) were Flosequinan significantly reduced resting office included. After a 4 week placebo run-in period, BP (Table 1); this was confirmed by the ambu- patients received 30 mg flosequinan daily as a latory BP monitoring. single morning dose for 4 weeks. The dose was Resting heart rate was significantly increased. then increased to 50 mg once daily, if resting Body weight remained unchanged, suggesting seated diastolic BP remained > 90 mm Hg. The absence of fluid retention. BP at peak exercise dose was further increased to 75 mg and 100 mg was not changed by flosequinan (225.7 ± 5.6/ once daily at the end of the 8th and 12th weeks 112.9 ± 2.8 and 226.4 ± 2.5/110.7 ± 3.4 mm Hg respectively, using the same criterium. At the respectively). GFR and RBF were preserved, 150P Proceedings of the BPS, 9-11 September 1987 RVR was significantly reduced. Side effects were monotherapy effectively lowers BP in hyper- generally mild and transitory (except in the patient tensive patients; it has a favourable renal haemo- who dropped out) and included oedema of the dynamic profile. feet, headache, palpitations and epigastric dis- comfort. We thank the Boots Company for the supply of flose- The present findings indicate that flosequinan quinan.

Table 1 Blood pressure and renal haemodynamic response to flose- quinan Week 0 Week 20 Resting office BP (mm Hg) systolic 159.2 ± 4.6 143.7 ± 4.2** diastolic 103.7 ± 1.5 93.3 ± 2.3** Heart rate (beats min-') 74.2 ± 1.9 82.7 ± 2.5** Ambulatory BP (mm Hg) systolic 148.4 ± 3.9 136.1 ± 4.1** diastolic 99.4 ± 2.9 90.5 ± 3.1** Body weight (kg) 75.8 ± 2.9 75.6 ± 3.4 GFR (ml min-') 125.4 ± 9.9 125.8 ± 8.3 RBF (ml min-') 763.3 ± 69.3 747.3 ± 59.7 RVF (mm Hg ml-' min-') 0.178 ± 0.026 0.156 ± 0.014* Values are mean ± s.e. mean; n = 9; *P < 0.05; **P < 0.01

Dupont, A. G. et al. (1987). Br. J. clin. Pharmac., 24, Tauxe, W. N. et al. (1971). Mayo Clin. Proc., 46, 524. 106.

Changes in lignocaine disposition in patients was halved in patients with moderately severe with acute ventricular arrhythmias CHF. Blood samples were withdrawn during and after the infusion for the analysis of serum A. H. THOMPSON, A. W. KELMAN, lignocaine (h.p.l.c., Nation et al., 1979) and P. J. DE VANE, W. S. HILLIS & B. WHITING AAG (laser nephelometry). Clearance estimates Department of Materia Medica, Stobhill General were obtained at 5 hourly intervals by fitting in- Hospital, Glasgow G21 3UW dividual data with a Bayesian parameter estima- tion program (Kelman et al., 1982). The influence Lignocaine concentrations continue to rise of weight, age, AAG and infusion time on clear- beyond the expected time of steady state during ance estimates was investigated by multiple linear longterm infusions. Changes in protein binding regression using the program NONMEM (Beal due to increased a,-acid glycoprotein (AAG) & Sheiner, 1979). following acute myocardial infarction (AMI) There was a significant fall in clearance from and product inhibition of metabolism may be the initial (0-5 h) estimate to that obtained fol- responsible for this phenomenon. This investi- lowing discontinuation of the infusion both in gation evaluated time-dependent changes in patients with AMI (28.2 ± 7.0 to 19.8 ± 5.0 1 LIG disposition in patients with potentially life- h-1) and without AMI (30.9 ± 12.2 to 21.2 ± 9.3 threatening ventricular arrhythmias. 1 h-1) (paired t-test, P < 0.01). AAG concentra- Thirty patients aged 46-86 years were studied. tions rose in patients with AMI, but there was Twenty-three patients had AMI and five had considerable variability in starting concentration, moderately severe cardiac failure (CHF). No and the rate and extent of changes. Multiple patient had clinical evidence of hepatic disease. linear regression analysis revealed that clearance An injection of 150 mg lignocaine HCl was was significantly influenced by weight, AAG administered intravenously over 2 min, followed concentration and infusion time, but not by age. by an infusion of 2 mg min-t for 48 h. This dose Infusion time was a better predictor of lignocaine Proceedings ofthe BPS, 9-11 September 1987 151P clearance than AAG concentration and there However, there was a wide inter-subject varia- was a small but significant improvement in fit bility on these parameters which limits the clinical when both factors were included in the model. application of this equation. The population equation based on the full model In summary, the decline in lignocaine clearance was: during longterm infusion can be related to time and AAG concentration. CL (1 h-') = 0.057 x weight (kg) - 0.209 x time (h) - 5.90 x AAG (g l-1)

Beal, S. L. & Sheiner, L. B. (1979). NONMEM Users Kelman, A. W. etal. (1982). Br. J. clin. Pharmac., 14, Guide. Division of Clinical Pharmacology, Univer- 247. sity of California, San Francisco. Nation, R. L. et al. (1979). J. Chromatogr., 162, 466.

The effect of nitrendipine on predose digoxin fibrillation and with a predose digoxin serum serum concentration concentration of < 1.5 ,ug 1-1 were included in the study. N. M. G. DEBBAS, A. JOHNSTON, Their predose digoxin serum concentration, S. H. D. JACKSON, S. 0. BANIM, A. J. CAMM & resting systolic and diastolic blood pressure P. TURNER (SBP and DBP) and heart rate (P) and 12 lead Departments of Clinical Pharmacology and Cardiology, ECG were monitored every day from day 1 to St Bartholomew's Hospital, London ECIA 7BE day 5 (period 1) and from day 8 to day 12 (period 2) of the study. From day 7 to 11, nitrendipine Nitrendipine is a potent antihypertensive calcium 20 mg twice daily was added to the patients' drug antagonist (Andren et al., 1982). When given regimen. concurrently with digoxin, nifedipine, a struc- Digoxin serum concentrations were determined turally related calcium antagonist, increases by fluorescence polarisation immunoassay digoxin concentrations by 45% (Belz et al., (Abbott TDX). The results were analysed using 1983). Evidence of a similar drug interaction for two way repeated measures analysis of variance nitrendipine is conflicting (Kirch et al., 1986; to determine the variance attributable to both Ziegler et al., 1986). This study investigates subjects and treatments. the possible steady state interaction between There is no evidence of a pharmacokinetic nitrendipine and digoxin. drug interaction between nitrendipine and digoxin Ten patients (seven males) aged 57 to 72 during chronic administration. Nitrendipine (mean 66) years receiving a fixed dose of between demonstrated its expected hypotensive effect in 0.125 mg and 0.5 mg of digoxin daily for atrial these patients.

Table 1 Mean values for periods 1 and 2 of the study, degrees of freedom (d.f.), variance ratio (F) and probability (P). Mean value Period 1 Period 2 d.f. F P Digoxin serum concentration 0.77 0.78 1,85 0 NS (p.g I-1) SBP 144 126 1,85 13.7 < 0.001 (mm Hg) DBP 85 75 1,85 20.6 < 0.001 (mm Hg) Pulse 77 77 1,85 0 NS (beats min-')

Andren, L. et al. (1982). J. cardiovasc. Pharmac., 4, Kirch, W. etal. (1986). Eur. J. clin. Pharmac., 31, 391. 387. Ziegler, R. et al. (1986). Second International Nitrendi- Belz, G. G. et al. (1983). Clin. Pharmac. Ther., 33, 410. pine Symposium, Lisbon. 152P Proceedings of the BPS, 9-11 September 1987 Bisoprolol in the treatment of mild and standing positions using a random zero hypertension sphygmomanometer. After the first and last doses of each active treatment, venous blood R. LEWIS, D. MACLEAN, D. McDEVITT & samples were taken at frequent intervals for 24 h A. JOHNSTON1 for measurement ofplasma drug concentrations. Department of Clinical Pharmacology, Ninewells The results are expressed as the reductions in Hospital and Medical School, Dundee, and 'Analytical blood pressure seen during treatment with biso- Unit, Clinical Pharmacology, St Bartholomew's prolol and atenolol relative to the preceding Hospital, London EClA 7BE placebo periods (Table 1). Analysis of variance showed significant differences (after adjustment Bisoprolol fumarate is a new 11-selective for period effect) in antihypertensive effect adrenoceptor antagonist which has several between the two ,3-adrenoceptor blockers for favourable pharmacokinetic properties including sitting systolic, standing systolic, and standing a long plasma half-life and high oral bioavail- diastolic blood pressures. In each case, a greater ability (90%). It is without intrinsic sympatho- antihypertensive effect was seen with bisoprolol. mimetic activity and has virtually no membrane There were no significant differences for reduc- stabilising activity. The aim of the present study tions in resting heart rate between the two treat- was to compare the efficacy, the safety and the ments (atenolol; -17.4 beats min-t, bisoprolol; pharmacokinetic properties of bisoprolol with -18.0 beats min-'). Examination of the pharma- those of atenolol in the treatment of patients cokinetic data for bisoprolol showed an elimina- with mild essential hypertension. tion half-life of 10.6 h after a single dose and 12.5 h Fourteen patients (mean age 56; range 37-62 during chronic administration. For atenolol, the years, eight females), with diastolic blood pres- corresponding figures were 7.2 and 6.8 h respec- sures within the range 90-120 mm Hg at the end tively. After single dosing, the clearance of biso- of a 4 week run-in period on placebo, entered a prolol was 274 ml min-1, compared with 328 ml double-blind placebo controlled crossover study min-' for atenolol. The clearance of both fell comparing the effects bisoprolol 10 mg once during chronic administration to 223 ml min- daily and atenolol 50 mg once daily. Treatment for bisoprolol and 285 ml min-' for atenolol. periods were each of 6 weeks duration and were The results suggest that bisoprolol may have a separated by a placebo period of 2-4 weeks. greater antihypertensive effect than atenolol at a Patients were reviewed at the ends of the second dose which appears to exert a similar degree of and sixth weeks of each active treatment period P-adrenoceptor blockade (Leopold et al., 1986). and at the end ofthe placebo period. Blood pres- The long half-life indicates that once daily dosing sures were recorded in triplicate in the sitting should achieve 24 h control of blood pressure.

Table 1 Reduction in blood pressure (mm Hg) (compared with placebo) with atenolol and bisoprolol Sitting Sitting Standing Standing systolic** diastolic systolic* diastolic** Atenolol -5.7 -10.7 -8.6 -7.3 Bisoprolol -21.9 -15.9 -22.8 -15.9 *P < 0.05, **P < 0.01 for differences between atenolol and bisoprolol

Leopold, W. et al. (1986). Br. J. clin. Pharmac., 22, 293. Proceedings of the BPS, 9-11 September 1987 153P oros with Efficacy of metoprolol compared numbers of patients were randomly allocated conventional metoprolol in extending the to 4 weeks' MET oros followed by 4 weeks' con- exercise tolerance of patients with angina ventional MET or to the reverse order. The pectoris single morning oros dose contained 190 mg MET for release at 14 mg h-1; conventional MET was S. BRANDMAN, M. CLARKE, given as 100 mg twice daily. D. ROYCHOUDHURY, A. JUBBER, I. DEWS, Exercise tolerance tests (24 h after oros, 12 h J. STEPHENS & M. VANDENBURG after conventional) were performed at the start Romford Cardiovascular Research, Department of ofthe study, at the crossover point and at the end Cardiology, Oldchurch Hospital, Romford, Essex of the study. Four patients were withdrawn (two unstable Metoprolol (MET) is a cardioselective 1B- angina, one AF, one non-specific ECG changes) adrenoceptor blocking drug, the short half-life Results from the 26 patients who completed the of which necessitates twice or three times daily study, were analysed by Hills & Armitage cross- administration. A novel delivery system ('oros, over techniques. Alza Corporation) allows osmotic release in the As can be seen from Table 1, the only impor- g.i. tract and provides virtually constant plasma tant differences between the treatments were in levels for 24 h (Grainger et al., 1985). We there- heart rate (and hence in double product), MET fore compared MET oros with conventional oros leading to a greater degree of ,B-adreno- MET in extending the exercise tolerance of ceptor blockade. patients with angina. We conclude that once daily metoprolol oros The double-blind, double dummy crossover is at least as effective as twice daily conventional study included 30 patients with a history ofstable metoprolol when assessed in this way and that angina and either an abnormal exercise tolerance it results in a slightly greater 1-adrenoceptor test or at least 60% narrowing of a main coronary blockade at the doses used. artery or primary branch on angiography. Equal Table 1 Minimum difference Estimated detectable Conventional Oros effect of (a = 0.05; Parameter Mean (s.d.) Mean (s.d.) treatment P 1-f3 = 0.80) Systolic BP start of 132 (17) 123 (12) 8.1 0.003 exercise (mm Hg) Systolic BP end of 159 (20) 154 (26) 5.8 NS 7.3 exercise (mm Hg) Diastolic BP start of 83 (7) 82 (8) 1.2 NS 6.4 exercise (mm Hg) Diastolic BP end of 86 (10) 83 (8) 2.5 NS 8.3 exercise (mm Hg) Heart rate start of 73 (14) 70 (13) 3.5 NS 9.6 exercise (beats min-') Heart rate end of 119 (20) 113 (17) 5.8 0.020 exercise (beats min-') Double product start 96 (18) 86 (17) 10.0 0.006 exercise (min-' x mm Hg/100) Double product end 190 (46) 175 (50) 16.8 0.027 exercise (min-' x mm Hg/100) Maximum ST depression (mm) 1.4 (0.9) 1.4 (0.9) NS 0.60 Duration to angina (s) 530 (141) 533 (167) -6 NS 103 Duration to end of exercise (s) 563 (125) 583 (136) -22 NS 80

Grainger, S. L. et al. (1985). Br. J. clin. Pharmac., 19, 2395. 154P Proceedings ofthe BPS, 9-11 September 1987

The combination ofalinidine and other anti- and EHR (min EHR with combination 116 ± anginal drugs on heart rate and blood 2.4; ATEN 129 ± 3.1; ALIN 148.7 ± 3.0 beats pressure in man minm-), and a reduction (P < 0.05) in SBP in the supine and standing position when compared D. W. HARRON, A. H. DEERING, M. SCOTT, with ALIN alone. The second study compared M. McMAHON & R. G. SHANKS the effects of ALIN, nifedipine retard 20 mg Department of Therapeutics and Pharmacology, The (NIF), ALIN combined with NIF and PLAC, Queen's University of Belfast, The Whitla Medical using the same procedures. The increased supine, Building, 97 Lisburn Road, Belfast BT9 7BL Northern standing and EHR associated with NIF was Ireland reduced when NIF was combined with ALIN; the reductions were significant at 2 and 4 h in the Alinidine is a specific bradycardic agent which supine position, 4 h standing (93.7 ± 9.2, 83.7 ± reduces heart rate by a direct action on the sinus 5.7 beats min-' NIF and combination of NIF node, without affecting cardiac conduction or and ALIN respectively), and 2 and 4 h after contraction (Kobinger et al., 1979) and is of exercise. No further significant decrease occurred value in the treatment of angina (Meinertz etal., in SBP or DBP with the combination compared 1981). Many other drugs, e.g. ,3-adrenoceptor to NIF alone. In the third study the volunteers antagonists, calcium antagonists and nitrates are were supine for 15 min when HR and BP were used alone and in combination for the treatment measured, stood, with HR and BP measured of angina. We have evaluated the effects of a every minute for 6 min, and then received ALIN combination of alinidine and drugs from each of or PLAC; 2 h later the subject rested supine for these groups on heart rate and blood pressure 15 min, but as he moved from the supine to in man. standing position chewed a GTN tablet; HR and Observations were made in three groups of six BP were recorded each min for 6 min. ALIN healthy male volunteers (age 19-33 years, body reduced (P < 0.05) the increase in HR after weight 60-78.9 kg); in all studies, drugs were GTN at all time intervals (1, 2, 3, 4, 5 and min) given double-blind in random order at weekly compared with GTN administered after PLAC intervals. In the first study subjects were admin- (3 min standing HR, GTN after PLAC 105 ± istered alinidine 30 mg (ALIN), atenolol 25 4.3, GTN after ALIN 86.8 ± 6.7 beats min'1). mg (ATEN), ALIN and ATEN combined and SBP was lower at all time intervals with GTN placebo (PLAC). Observations were made taken in the presence of ALIN compared with before and 2, 3, 4, 6 and 8 h after drug admin- GTN in the presence of PLAC. No adverse istration. At each observation time the subjects effects were reported with the combination of were supine for 15 min, stood for 3 min and ALI and ATEN or ALIN and NIF; four subjects exercised by stepping on and off a box 46 cm in had transient syncopal attacks with ALIN and height at a rate of 32 steps min-1 for 3 min. GTN. Systolic and diastolic blood pressure (SBP, DBP) In conclusion, the reductions in EHR with and heart rate (HR) were measured at the end of ALIN were lowered (P < 0.05) when ATEN was the supine and standing period and heart rate administered with ALIN; the reflex increases (EHR) within 5 s of completing exercise. Con- in HR that occurred with NIF and GTN admin- comitant administration of ALIN and ATEN istration were reduced (P < 0.05) when ALIN caused reductions (P < 0.05) in supine, standing was administered concomitantly. Kobinger, W. et al. (1979). Naunyn-Schmiedeberg's Meinertz, E. et al. (1981). Circulation, 64, 294. Arch. Pharmac., 306, 255.

Ibopamine (SK&F 100168) does not Ibopamine (IB) is an orally administered analogue potentiate the cardiovascular response to of dopamine with dopaminergic, a- and j- tyramine in healthy subjects adrenoceptor agonist activity. Studies in dogs showed that IB potentiated the pressor response J. LOCKE-HAYDON, S. C. SCOTT & to tyramine, though it did not inhibit monoamine B. L. B. VILLAR oxidase activity in vitro. This study assessed the Department of Clinical R & D SK&F Research Ltd, effect of IB on tyramine-induced cardiovascular The Fryth, Welwyn, Herts AL6 9AR (introduced by responses in healthy subjects. Carol Harvey) Six normal subjects (two male, four female, Proceedings of the BPS, 9-11 September 1987 155P mean age 32.2 years) entered a double-blind, dose. Low intra-subject variability was seen in within-subject, placebo-controlled, randomized response to tyramine both within and across cross-over study. Each subject received a single study days. For individual subjects there was 200 mg oral dose of IB or placebo on two separate little difference between cardiovascular re- occasions. A tyramine challenge test (TCT) and sponses to tyramine after IB and after placebo. RIA measurement ofplatelet monoamine oxidase Results for mean baseline (Base), area under the activity (PMAO) were performed before and 30 curve from 0-10 min after tyramine expressed as min after dosing. TCTs consisted of increasing change from mean baseline divided by time bolus does of i.v. tyramine (2-8 mg) given until (AUC) and maximal increase from mean base- systolic BP rose by 30 mm Hg, to establish a line after tyramine (Max Inc) at the 4 mg tyramine common dose for analysis. BP and heart rate dose are shown below. (HR) were recorded at 0.5 min intervals for 2 IB did not inhibit PMAO activity. Four sub- min before and for 10 min after each dose of jects experienced ECG changes (three T wave tyramine. changes, one occasional unifocal ventricular Tyramine caused dose-dependent increases ectopics) on both study days which were con- in systolic BP and similar but less pronounced sidered related to tyramine administration. IB at increases in diastolic BP. Responses were a dose of200 mg did not alter detectably tyramine- maximal within 1.5 to 2.5 min and resolved induced cardiovascular responses in healthy sub- within 7 to 8 min. HR responses varied between jects. subjects and showed no clear trend with increasing

Table 1 Results of analysis of covariance, 4 mg tyramine dose Ibopamine (IB) Placebo (P) Difference Parameter mean* mean* (IB-P) 95% CI difference Systolic Base 118.2 118.5 BP (mm Hg) AUC -0.4 -1.1 +0.7 (-4.0, 5.3) Max Inc +13.8 +11.4 +2.4 (-5.6, 10.3) Diastolic Base 65.1 66.0 BP (mm Hg) AUC -3.1 -2.9 -0.2 (-3.0, 2.6) Max Inc +8.6 +5.5 +3.1 (-1.1, 7.7) Heart Base 61.1 59.2 rate AUC +0.1 -0.3 +0.4 (-1.4, 2.2) (beats min-') Max Inc +9.1 +7.8 +1.3 (-10.1, 12.6) *Means are covariate adjusted means

Disposition of ritodrine in pregnant and physiological changes during pregnancy can affect nonpregnant women drug disposition. In pregnant women only rito- drine half-lives have been reported (Kuhnert et A. S. GROSSt, J. A. BAIRD-LAMBERTV & al., 1986). K. F. BROWN (introduced by M. Eichelbaum) Nine pregnant women (gestation 28 ± 3 weeks Department of Pharmacy, University of Sydney, and age 25 ± 4 years (means ± s.d.)) and thirteen 'Paediatric Pharmacology Unit, University of Sydney, nonpregnant women (age 26 ± 5 years) were Westmead Hospital, Sydney, Australia studied. Preterm uterine contractions had ceased in all pregnant women during intra- Ritodrine is a 02-adrenoceptor agonist widely venous ritodrine therapy. The infusion regimen used in obstetrics to halt preterm labour. The was individualised in response to maternal heart present study was initiated to characterise the rate and contractions, however the final infusion disposition of ritodrine in pregnant and non- rate (102 ,ug min-') was the same in all patients. pregnant women. Pharmacokinetic parameters Blood samples were withdrawn half-hourly for have been reported in nonpregnant women 2 h prior to, and at cessation of, the infusion to (Caritis et al., 1985), however the profound ensure that steady-state conditions (SS) had 156P Proceedings of the BPS, 9-11 September 1987 been attained. Further samples were taken at < 0.012) than that calculated using plasma con- timed intervals for 6 h post-infusion. Nonpregnant centrations (2.2 ± 1 1 min-'). women were studied during, and for 8 h after, a Ritodrine plasma clearance was greater in 1 h infusion ofritodrine (154 ,ug min'). Ritodrine pregnant than nonpregnant women, even when concentrations in plasma and a number of whole normalised for body weight (Table 1). The ter- blood aliquots were determined by h.p.l.c. minal half-life and mean residence time were (Gross et al., 1987). Pharmacokinetic parameters shorter in pregnant women, whereas V., normal- were calculated from post-infusion plasma con- ised for body weight, was larger in nonpregnant centration-time data using standard techniques. women. The disposition of ritodrine therefore In all patients SS had been attained at cessation differs in pregnant and nonpregnant women, of the infusion. Steady-state plasma nd blood and consequently pharmacokinetic parameters concentrations were 46.8 ± 3.6 ,ug I ' and 75.4 ± determined in nonpregnant women cannot be 11.9 ,ug I` (n = 8) respectively. Total clearance used to design dosage regimens for pregnant calculated from the SS infusion rate and blood women in preterm labour. concentrations (1.4 ± 0.3 1 min-1) was lower (P

Table 1 Pharmacokinetic parameters (mean ± s.d.) describing the disposition of ritodrine in pregnant and nonpregnant women Pregnant women Nonpregnant women P value' CL (1 min-1) 2.2 ± 0.3 1.4 ± 0.2 P < 0.001 (1 min-' kg-') 0.030 ± 0.006 (n = 6) 0.026 ± 0.005 P < 0.008 Vss (1) 203 ±44 265 ± 91 NS (1kg-') 2.8 ± 0.5 (n = 6) 4.8 ± 1.7 P < 0.01 MRT (h) 1.5 ± 0.3 3.2 ± 1.5 P< 0.001 tv½,z2 (h) 2.1 3.1 P < 0.02 'Mann-Whitney U test, 'Harmonic mean

Caritis, S. N. et al. (1985). Am. J. Obstet. Gynecol., Kuhnert, B. R. etal. (1986). Clin. Pharmac. Ther., 40, 152, 1026. 656. Gross, A. S. et al. (1987). J. Chromatogr., 416, 400. tPresent address: Dr Margarete Fischer-Bosch-Institute ftir Klinische Pharmakologie, Auerbachstrasse 112, 7000 Stuttgart 50, F.R.G.