Ann. rheum. Dis. (1974), 33, 304 Ann Rheum Dis: first published as 10.1136/ard.33.4.304 on 1 July 1974. Downloaded from Withdrawal of allopurinol in patients with gout W. Y. LOEBL AND J. T. SCOTT From Charing Cross Hospital and Kennedy Institute of Rheumatology, London The xanthine oxidase inhibitor allopurinol effectively within one week of discontinuation, regardless of the lowers the plasma level of uric acid and the drug has duration of therapy (Fig. 1). In a few instances, how- become widely used in the treatment of gout, ever, pretreatment values were not regained until 2 or especially in patients with renal failure, uric acid 3 weeks after stopping the drug. calculi, or intolerance to uricosuric agents (Scott, Hall, and Grahame, 1966). Various theoretical com- (2) BLOOD UREA plications of treatment have been considered from Pretreatment blood urea levels had been 45 mg/ time to time, such as possible incorporation of ribo- 100 ml or below in all the patients in whom allo- nucleotide into genetic material or the effects of crys- purinol was stopped in the absence of side effects, tals of allopurinol in voluntary muscle, as discussed but was higher in some of the patients in whom the below. For these reasons it was thought reasonable a drug was stopped because of such side effects. The few years ago to determine the effect ofdiscontinuing mean blood urea in all patients before allopurinol allopurinol therapy in gouty patients who were not was started had been 41 mg/100 ml (SD 10), and over-producers of uric acid and whose renal function showed no significant change during allopurinolcopyright. was not impaired. treatment (39 mg/100 ml; SD 12), or after allopurinol was discontinued (37 mg/100 ml; SD 11). Plan of study Figures for creatinine clearance both before and Medication was discontinued in 33 patients with gout after treatment were available in only five subjects; (32 men and one woman), with a mean age of 58 years these showed no change after discontinuation (mean 105 ml/min before treatment, 114 ml/min after treat- (range 33-75 yrs). In five ofthem the drug would have had http://ard.bmj.com/ to be discontinued in any case because of a skin rash or ment was discontinued). malaise probably attributable to the drug; in 28 the drug was stopped in the absence of side effects after full discus- (3) CLINICAL sion with individual patients. None of these latter patients Up to the time this analysis was made there had been a had impairment of renal function (as estimated by blood recurrence of gouty arthritis in twelve patients; 21 urea) and none were over-producers of uric acid as indi- patients have remained well and free of symptoms. cated by a 24-hour urinary uric acid excretion of less than have a 600 mg on a low-purine diet. Thirteen patients restarted the drug (after The mean length ofhistory ofgout before starting treat- mean duration off treatment of 55 weeks). The usual on September 25, 2021 by guest. Protected ment had been 15 years (range 05-42 yrs), with an average reason for restarting treatment has been the recur- of 4-5 attacks per year before starting therapy. The mean rence of gouty arthritis, but in four patients the drug duration of allopurinol treatment before the drug was was started relatively early after it was discontinued, discontinued was 93 weeks (range 19-236 wks), and the because either the patient or his physician preferred mean duration off allopurinol at the time this analysis to do so; treatment was restarted in one patient be- was made was 86 weeks (range 14-210 wks). cause of uric acid crystalluria (though his 24-hour urinary uric acid before treatment had not been Results raised and previous microscopy of urine had shown (1) PLASMA URIC ACID no abnormality). Treatment was restarted in one The mean level of plasma uric acid before starting patient who had remained symptom-free for 3 years therapy had been 8-4 mg/100 ml (SD 1 1), falling to off the drug but who was to have a prostatectomy 5.5 mg/100 ml (SD 1-2) after allopurinol therapy was operation; it was thought wise to avoid a risk of post- established. After the withdrawal of allopurinol, uric operative gout. acid levels rose to pretreatment figures in all patients At the time of analysis twenty patients were still (mean 8-8 mg/100 ml, SD 1X2). This rise in plasma not taking allopurinol after a mean duration off treat- uric acid took place rapidly after stopping the drug ment of 107 weeks. Fifteen of these patients had and the level usually achieved its pretreatment value remained free of gout and five had had a mild recurrence. The course of all 33 patients is indicated Accepted for publication January 25, 1974. Presented at a meeting of the Heberden Society, November, 1973. in Fig. 2. Ann Rheum Dis: first published as 10.1136/ard.33.4.304 on 1 July 1974. Downloaded from Withdrawal ofallopurinol in patients with gout 305 @0 go 3 3 0 9 S I . 3- . 8 S . *0 0 . I 0 0 6- a,P i S. I a 4 3 copyright. i i 7 9 10 WEEK S FI G. 1 Plasma uric acid levels before stopping allopurinol andfor 10 weeks afterwards A comparison of various factors between those Seegmiller, 1969), and in a patient with lympho- http://ard.bmj.com/ patients suffering a recurrence of gout after stopping sarcoma who received allopurinol for control of treatment and those who have had no recurrence as hyperuricaemia (Band, Silverberg, Henderson, Ulan, yet is indicated in the Table. There is no significant Wensel, Banerjee, and Little, 1970). Possible effects of difference between the two groups with regard to the allopurinol on iron metabolism have not been con- mean age at stopping allopurinol, mean duration of firmed (Emmerson, 1966; Boyett, Vogler, de Paula clinical gout, mean duration ofallopurinol treatment, Furtado, and Schmidt, 1968), but it appears that the mean daily dose of and the mean allopurinol, initial drug increases the risk of bone marrow damage in on September 25, 2021 by guest. Protected plasma uric acid. Those patients having no recurrence ofgout, however, are seen to have had a better control of plasma urate level while taking the drug (mean Table Status after stopping allopurinol 5-1 mg/100 ml) than those who have had a recurrence of gouty arthritis (mean 6-2 mg/100 ml). Recurrence of No recurrence gout yet Discussion Mean age at stopping 58 2 yrs 57 3 yrs allopurinol Apart from the occasional occurrence of skin rashes, particularly in patients with renal failure, allopurinol Mean duration of 16 yrs 15 yrs appears to have remarkably few side effects. Because clinical gout of its effect on inhibitory purine biosynthesis (in Mean duration allo- 82 wks 99 wks addition to its action as an inhibitor of xanthine purinol treatment (±SD 54) (±SD 59) oxidase), the anticipated complication of xanthine stone formation occurs with extreme rarity. It has Mean daily dose 388 mg 368 mg in fact been recorded only in patients with the allopurinol Lesch-Nyhan syndrome, where allopurinol fails to Mean initial PUA 8-6 mng/100 ml 8-4 mg/100 ml suppress purine biosynthesis and the urinary excretion rate of the oxypurines hypoxanthine and xanthine Mean PUA during 6-2 mg/100 ml 5 1 mg/lOO ml is high (Seegmiller, 1968; Greene, Fujimoto, and treatment (±SD 1-4) (±SD 0-9) ,' - .*,' :.,*.,,;, ,- " - i,',, 306 Annals ofthe Rheumatic Diseases Ann Rheum Dis: first published as 10.1136/ard.33.4.304 on 1 July 1974. Downloaded from DURATION OFF ALLOPURINOL PATIENTS REQUEST RECURENCE OF GOUT LPATIENTS REQUEST NO FURTHER GOUT J PATIENTS REQUEST J CRYSTALLURIA J ALLOPURINOL RESTARTED PA N R U ................._PATIENT'S REOUEST ........................P.E.... i.....1 PER TM copyright. 5O ISO 200 WEEKS FIG. 2 Clinical course ofall 33 patients after stopping allopurinol http://ard.bmj.com/ patients with neoplastic diseases who are receiving required forre-accumulation ofurate, its precipitation chemotherapy, particularly cyclophosphamide, prob- in solid form, and the subsequent development of ably because of an interaction between allopurinol gouty arthritis. In this context it is of interest that and cytotoxic drugs (Boston Collaborative Drug there was no significant difference with regard to Surveillance Program, 1974). Crystals of hypoxan- duration of allopurinol treatment between those sub- thine, xanthine, and oxipurinol have been found in jects who have not yet had a recurrence of gouty skeletal muscle biopsies from patients with gout who arthritis compared with those who have; but control on September 25, 2021 by guest. Protected were being treated with allopurinol (Watts, Scott, of plasma urate levels while taking the drug had been Chalmers, Bitensky, and Chayen, 1971), but this better in the former than in the latter. finding does not appear to have any clinical signifi- Assessment ofrenal function was not entirely satis- cance. A theoretical possibility has been the incor- factory because some of the patients were seen for the poration of allopurinol ribonucleotide into nucleic first time after treatment was started, and in most acids, but experimental support for this is lacking subjects levels of creatinine clearance before, during, (Nelson, Bugge, Krasny, and Elion, 1973; Nelson and after treatment were not available for compari- and Elion, 1974). son. The few which were, however, showed no change The present study was begun at a time when the last and levels of blood urea in all subjects remained two possibilities were perhaps causing more anxiety constant, with no indication of any overall change than is the case at present; it was consideredjustifiable either during treatment or after its cessation.