We searched The Cochrane
Neuromuscular Disease Group Register, The Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 3, 2010), MEDLINE, EMBASE and reference lists of articles up to July 2010.
SELECTION CRITERIA: Three authors independently selected trials for inclusion, assessed risk of bias and extracted data. We contacted study authors for additional information.
MAIN RESULTS: We identified 23 trials with a total of 1586 participants. Fifty-eight per cent of these participants were from five unpublished studies.
Quinine was compared to placebo (20 trials, n =1140),
vitamin E (four trials, n = 543), a
quinine-
vitamin E combination (three trials, n = 510), a
quinine-
theophylline combination (one trial, n = 77), and
xylocaine injections into the gastrocnemius muscle (one trial, n = 24). The most commonly used
quinine dosage was 300 mg/day (range 200 to 500 mg).Compared to placebo,
quinine significantly reduced
cramp number over two weeks by 28%,
cramp intensity by 10%, and
cramp days by 20%.
Cramp duration was not significantly affected.A significantly greater number of people suffered minor adverse events on
quinine than placebo (risk difference +3%, 95% confidence intervals 0% to 6%), mainly gastrointestinal symptoms. Overdoses of
quinine have been reported elsewhere to cause potentially fatal adverse effects, but in the included trials there was no significant difference in major adverse events compared with placebo (risk difference 0%, 95% confidence intervals -1% to 2%). One participant suffered from
thrombocytopenia (0.12% risk) on
quinine.A
quinine-
vitamin E combination,
vitamin E alone, and
xylocaine injections into gastrocnemius were not significantly different to
quinine across all outcomes, including adverse effects. Based on a single trial comparison,
quinine alone was significantly less effective than a
quinine-
theophylline combination but with no significant differences in adverse events.
AUTHORS' CONCLUSIONS: There is moderate quality evidence that
quinine significantly reduces
cramp frequency, intensity and
cramp days in dosages between 200 and 500 mg/day. There is moderate quality evidence that with use up to 60 days, the incidence of serious adverse events is not significantly greater than for placebo in the identified trials. Further research is required on the optimal dose and duration of use, and also on alternative treatments.