Is quinine effective and safe in leg cramps?

Muscle cramp is a recurrent and painful condition and a common complaint among elderly subjects and patients treated with hemodialysis. It is commonly nocturnal and can disturb a good night's sleep. No specific cause can be identified; therefore, therapy is mostly symptomatic. Quinine sulfate, an antimalarial drug, is widely used as an effective therapy for idiopathic leg cramps. Several double-blind, randomized, placebo-controlled studies have questioned the effectiveness of quinine in leg cramps; whereas other studies have shown significantly more benefit with use of quinine in reducing the frequency and severity of cramps compared with placebo or vitamin E. The mechanism of this beneficial effect is obscure, however. Quinine appears to decrease the excitability of the motor end plate, thereby reducing the muscle contractility. Most patients consider quinine beneficial for their leg cramps, which is difficult to refute by scientific data. More important, cramp is a subjective symptom, therefore difficult to measure objectively. Consequently, scientific studies designed to prove or disprove the effectiveness of quinine can be subject to flaws. Further, a dosage of 200 to 300 mg of quinine every night has not been shown to cause significant side effects. Nevertheless, quinine should be used in a small dose and cautiously, especially in the elderly and patients with renal failure, and should be avoided in patients with liver disease.