• N Sato, J M Brum, H Mitsumoto, and G E DeBoer.
• Division of Anesthesiology, Cleveland Clinic Foundation, OH 44195, USA.
• Can J Anaesth. 1995 Feb 1;42(2):158-62.

AbstractTwo case reports have cited the recreational use of cocaine as possible trigger of a malignant hyperthermia (MH) crisis. We evaluated whether toxic concentrations of cocaine altered the in vitro muscle response to halothane during contracture tests for MH. Twenty-two patients were studied. Muscle biopsies were obtained and first tested for MH susceptibility with 3% halothane and caffeine contracture testing. Ten patients were diagnosed as MH-susceptible and 12 as MH non-susceptible, in accordance with the North American Malignant Hyperthermia Group protocol. Then, muscle strips were exposed to 1% halothane in the presence and absence of 0.1 mmol.L-1 cocaine. Cocaine alone did not affect baseline muscle tension in either group. With 1% halothane, MH non-susceptible muscle showed no contracture with or without cocaine. In contrast, in the presence of 1% halothane, MH-susceptible muscle showed either no change in contracture (six patients), an increase (two patients), or a decrease (two patients) when exposed to cocaine. However, the overall effect of cocaine on muscle contracture in the presence of 1% halothane was insignificant in both groups. We conclude that cocaine, even at toxic levels, does not have a direct effect on skeletal muscle contractility and thus is safe for MH-susceptible patients.

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