The effects of calcium channel blocking drugs on halothane initiation of malignant hyperthermia in MHS swine and on the established syndrome.

We have investigated in malignant hyperthermia susceptible swine in vivo the effects on halothane initiation of the MH syndrome and on the established syndrome of five calcium channel blocking drugs--nifedipine, nisoldipine, diltiazem, verapamil and flunarazine. Nifedipine alone caused attenuation of halothane-initiated malignant hyperthermia to the extent of blocking onset of the syndrome in 29% of animals for the 60 minute period of exposure. In the face of the established malignant hyperthermia syndrome, all the drugs tested were therapeutically completely ineffective.