In-vitro-effects of cocaine in skeletal muscle specimens of patients suscriptible to malignant hyperthermia

Objective: The abuse of cocaine can cause serious medical complications like tachycardia, rhabdomyolysis, and hyperthermia. Because of the clinical similarities, it has been suggested that cocaine might be a trigger of malignant hyperthermia (MH). Therefore, aim of this study was to investigate the in-vitro effects of cocaine in skeletal muscle specimens of MH susceptible (MHS) and normal (MHN) patients. Methods: 62 patients undergoing the in-vitro contracture test (IVCT) according to the protocol of the European MH Group (EMHG) for diagnosis of MH susceptibility were included in this study. In muscle specimens surplus to diagnostic requirements cocaine was added in order to achieve tissue bath concentrations of 0.01, 0.1 and 1.0 mM. The contracture development and twitch response have been registered. Results: 21 patients were diagnosed as MHS and 36 patients as MHN. 5 patients tested as MH-equivocal (MHE) were excluded from the study. Following bolus administration of cocaine, no contracture development was observed in MHS, as well as MHN specimens. The muscle twitch decreased after cocaine administration significantly in both diagnostic groups. Conclusion: In contrast to the established MH trigger substances like volatile anaesthetics, cocaine produced no contracture development in MHS muscle specimens. Furthermore, cocaine produced a negative inotropic effect in all skeletal muscle preparations, which might be explained by local anaesthetic effects. Regarding these results, cocaine seems not to be a MH trigger agent.