Protection from halothane-induced porcine malignant hyperthermia syndrome by droperidol.

A group of 43 pigs from eight litters of purebred Pietrains were identified as malignant hyperthermia susceptible by halothane testing, and their reaction time (measured in seconds from the onset of halothane administration of the onset of skeletal muscle rigidity) was recorded. One week later, these pigs were treated with 0.02, 0.2, 0.5, 1.0 or 2.0 mg/kg of droperidol 1 hour prior to a second halothane test. Pigs with a post-droperidol reaction time of greater than 100.4 seconds (mean + 2.021 SD of initial reaction time) were considered to be protected from malignant hyperthermia. Droperidol afforded some degree of protection at all doses tested. The effective dose50 was determined to be 0.055 with 95% confidence limits of 0.017 to 0.183 mg/kg.