Efficacy of hydroquinine in preventing frequent ordinary muscle cramp outlasts actual administration.

In order to compare the efficacy of a daily dose of 300 mg hydroquinine hydrobromide and placebo in preventing frequent ordinary muscle cramp, we designed a randomized, double-blind, placebo-controlled study of three consecutive 2-week periods viz. a qualification period, a medication period and a wash-out period. Twenty healthy adult volunteers experiencing at least 3 muscle cramps a week (6 men, 14 women aged 38-78 yrs) were enrolled into this study, and 19 of them completed it. Hydroquinine hydrobromide (300 mg/day) was administered to group 1 (10 women) and placebo to group 2 (4 women, 6 men). The frequency, severity, duration and location of muscle cramps as well as short-term adverse drug effects were recorded in daily diaries. Compared with placebo the decrease in the mean number of muscle cramps (16.1 or 58%) in the active drug treatment group during the medication period was highly significant (Wilcoxon test p = 0.004). During the wash-out period this decrease partly persisted (8.9 or 33%). In this study a daily dose of 300 mg hydroquinine hydrobromide was effective in preventing frequent ordinary muscle cramp in healthy female volunteers. The effects of hydroquinine outlasted its administration. The drug was well tolerated.