N-[4-[4-(Ethylheptylamino)-l-hydroxybutyl] phenyl] methanesulfonamide,(E)-2-butenedioate (2: l) salt (ibutilide fumarate, 2E), has been found to have Class I11 antiarrhythmic activity. In an in vitro rabbit heart tissue preparation designed to evaluate the cardiac electrophysiology of potential antiarrhythmic agents, it selectively prolongs the effective refractory period of papillary muscle. In vivo it increases the ventricular refractory period of the canine heart ...
