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.