of the risk of gynaecomastia associated with cimetidine, omeprazole and other antiulccr medications. BM J 1994; 308: 503-06. Jick H, Jick SS, Gurewich V, Myers MW, Vasilakis C. Risk of idiopathic cardiovascular death and nonfatal venous thromboembolism in women using oral contraceptives with differing progestagen components. Lancet 1995; 346: 1589-93. Methods This randomised, double-blind, placebo-controlled, parallel-group trial consisted of three consecutive 2-week periods: qualification, treatment, and washout. 68 women and 44 men who had at least three muscie cramps per week w ere e n ro lle d . D uring th e tre a tm e n t period, participants were randomly assigned 300 mg daily dose of hydroquinine hydrobromide dihydrate (54 participants) or placebo (58). The frequency, severity (1-10), duration, and location of muscle cramps, as well as any side-effects, were recorded by participants in daily diaries. The primary outcome measures were the number of muscle cramps and the number of days during which the participants had muscle cramps (cramp-days).Findings We excluded five participants from both groups from the analysis. Thus, data from 49 hydroqulnine-group p a rticip a n ts and 53 placebo-group p a rtic ip a n ts were analysed. In both groups the to ta l number of muscle cramps and the number of cramp-days decreased during the tre a tm e n t period compared w ith the qualification period. However, these improvements were greater in the hydroquinine group th a n in th e placebo group. The Correspondence to: Prof A L M Verbeek hydroquinine-group participants reported a median of 8 (95% Cl 7-12) fewer cramps and median of 3 (1-4) fewer cramp-days, whereas those on placebo reported only 3 (0-5) fewer cramps and 1 (0-5) fewer cramp-days. 32 (65%) of participants in the hydroquinine group had a 50% or greater reduction in the number of muscle cramps. After the onset of cramps, hydroquinine did not reduce the severity or duration of cramps. We also found a sustained effect after treatment had stopped. Hydroquinine was well tolerated, and resulted in only mild side-effects. InterpretationIn our study, 300 mg hydroquinine was safe to take in the short-term and significantly more effective than placebo in the prevention of frequent, ordinary muscle cramps. This therapeutic effect outlasted the duration of treatment.

of the risk of gynaecomastia associated with cimetidine, omeprazole and other antiulccr medications. BM J 1994; 308: 503-06. Jick H, Jick SS, Gurewich V, Myers MW, Vasilakis C. Risk of idiopathic cardiovascular death and nonfatal venous thromboembolism in women using oral contraceptives with differing progestagen components. Lancet 1995; 346: 1589-93. Methods This randomised, double-blind, placebo-controlled, parallel-group trial consisted of three consecutive 2-week periods: qualification, treatment, and washout. 68 women and 44 men who had at least three muscie cramps per week w ere e n ro lle d . D uring th e tre a tm e n t period, participants were randomly assigned 300 mg daily dose of hydroquinine hydrobromide dihydrate (54 participants) or placebo (58). The frequency, severity (1-10), duration, and location of muscle cramps, as well as any side-effects, were recorded by participants in daily diaries. The primary outcome measures were the number of muscle cramps and the number of days during which the participants had muscle cramps (cramp-days).Findings We excluded five participants from both groups from the analysis. Thus, data from 49 hydroqulnine-group p a rticip a n ts and 53 placebo-group p a rtic ip a n ts were analysed. In both groups the to ta l number of muscle cramps and the number of cramp-days decreased during the tre a tm e n t period compared w ith the qualification period. However, these improvements were greater in the hydroquinine group th a n in th e placebo group. The Correspondence to: Prof A L M Verbeek hydroquinine-group participants reported a median of 8 (95% Cl 7-12) fewer cramps and median of 3 (1-4) fewer cramp-days, whereas those on placebo reported only 3 (0-5) fewer cramps and 1 (0-5) fewer cramp-days. 32 (65%) of participants in the hydroquinine group had a 50% or greater reduction in the number of muscle cramps. After the onset of cramps, hydroquinine did not reduce the severity or duration of cramps. We also found a sustained effect after treatment had stopped. Hydroquinine was well tolerated, and resulted in only mild side-effects. InterpretationIn our study, 300 mg hydroquinine was safe to take in the short-term and significantly more effective than placebo in the prevention of frequent, ordinary muscle cramps. This therapeutic effect outlasted the duration of treatment.