Hydroquinine, is an organic compound and as a cinchona alkaloid closely related to quinine.

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).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.

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.