![]() In 2009, the US Food and Drug Administration (FDA) explicitly noted an unfavourable risk–benefit ratio for quinine when used for leg cramps. 6Īlthough quinine is modestly effective, concerns regarding potential adverse effects have tempered enthusiasm about its use for nocturnal leg cramps. 30, 2010, Health Canada had received 71 reports of serious adverse reactions suspected of being associated with quinine use (41 were either life threatening or required hospital admission). 2 Quinine is contraindicated in patients with a known hypersensitivity, a history of immune thrombocytopenic purpura or thrombotic microangiopathy, G6PD deficiency, tinnitus, optic neuritis, prolonged QT interval or myasthenia gravis. ![]() 2 Severe drug interactions with aluminum-containing antacids, cholinesterase inhibitors, cimetidine, digoxin, neuromuscular blocking agents, warfarin and other agents can take place. 5 Intentional or inadvertent overdose can cause serious and even fatal arrhythmias. ![]() The incidence rate ratios were 4.2 (95% confidence interval 2.5–6.5) and 6.9 (95% CI 1.3–24.0), respectively, compared with diltiazem. In a study of Medicare claims data, the incidence per 1000 person-years with quinine was 1.67 for immune thrombocytopenic purpura and 0.23 for thrombotic microangiopathy. Of particular concern is the potential for rare but serious hematologic adverse effects (i.e., immune thrombocytopenic purpura and drug-mediated thrombotic microangiopathy). 3Ī variety of adverse effects can occur with the usual therapeutic doses of quinine, including cinchonism (marked by tinnitus, high-tone hearing loss, photophobia and other visual disturbances, dysphoria, headache, nausea, vomiting, sweating, dizziness and postural hypotension), hypoglycemia (from the drug’s stimulatory effect on pancreatic β cells most common in the treatment of severe malaria), hypotension (usually related to intravenous infusion of the drug), hearing and visual disturbances (including irreversible loss), gastrointestinal symptoms, cutaneous effects, conduction abnormalities (mild prolongation of the corrected QT interval, which is rare unless plasma levels are elevated), arrhythmias and hemolysis (from hypersensitivity or in patients with G6PD deficiency). 3, 4 Other pharmacologic measures were found to be either possibly effective (vitamin B complex, naftidrofuryl, calcium-channel blockers) or likely not effective (gabapentin, magnesium). Two systematic reviews published within the last five years both concluded that quinine is modestly effective (reduces cramp frequency by about a quarter, cramp intensity by a tenth and number of days by a fifth). 2 A number of drugs have been proposed for the treatment of nocturnal leg cramps. Quinine may help by decreasing the excitability of the motor end-plate and increasing the muscle refractory period. ![]() Usually idiopathic, these muscle cramps are common, particularly in older patients. Quinine sulfate at a dose of 200–300 mg at night has been used for many years to treat nocturnal leg cramps. Instead, I will focus on the role of quinine in the management of this common condition. I don’t intend to question this novel finding or speculate on the mechanism underlying the apparent seasonality of the condition. They found that new quinine prescriptions in the province of British Columbia and Internet searches using the term “leg cramps” in the United States both showed a sinusoidal pattern, with a midsummer peak and a midwinter dip. In a linked research article, Garrison and colleagues 1 report on the seasonal variability of nocturnal leg cramps.
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