Procaine in malignant hyperpyrexia.

The caffeine contracture of normal human muscle, which has been used as a model for malignant hyperpyrexia, is greatly potentiated by halothane. Prior administration of procaine markedly reduces the halothane-potentiated caffeine contracture, and procaine given at the height of the contracture induces relaxation. Lignocaine, on the other hand, produces a variable response and sometimes increases the contracture.The muscle from a patient with an inherited susceptibility to malignant hyperpyrexia contracted spontaneously with halothane alone, and this contracture was reversed by procaine.These experiments support the therapeutic use of procaine in malignant hyperpyrexia.