Electrophysiological effects of penticainide in the anaesthetized dog.

The cardiac electrophysiological effects of Penticainide, a new antiarrhythmic agent, were studied by means of intracardiac electrodes in the anaesthetized dog. Intravenous administration of 5 mg/kg of Penticainide reduced the sinus rate and prolonged the sinus node recovery time. Atrial refractory periods increased. Anterograde intranodal conduction slowed and nodal refractoriness increased. Conduction time in the His-Purkinje tissue and ventricle increased, as did the ventricular refractory periods. Monophasic action potential duration was not altered by the drug in the atrium or the ventricle. The mechanism of action of Penticainide as an antiarrhythmic drug seems to be correlated to its membrane effects: inhibition of the fast-inward current, responsible for the marked effects on His-Purkinje and ventricular tissues; and inhibition of the slow-inward current, suggested by its effects on sinus node and atrio-ventricular node.