Propafenone: a promising new antiarrhythmic agent.

(Chest 1990; 98:434-41) P ropafenone is a new class IC antiarrhythmic agent that has just l)een released in the United States for use in treatment o)f malignant ventricular arrhythmias (Rythmol, Knoll Pharmaceuticals, Whippany, New Jersey). It was first marketed in Europe in 1977, and has gained wide acceptance there and in Canada for the treatment of various types of ventricular and supraventricular arrhythmias. It acts primarily by inhibiting the fast inward sodium current. Like flecainide and encainide, it has very prominent conduction slowing effects, with relatively little change in repolarization and corrected QT interval. In addition, it has mild beta blocking effects and very weak calcium entry blocking action. It is extensively metabolized, with tWO) known active metabolites, the formation of one ofwhich is genetically determined. Its metabolism is saturable, with bioavailability increasing with higher dosage .It exhibits very strong suppression of ventricular ectopy, with more varial)le efficacy in sustained ventricular tachycardia. It is also very effective in controlling all forms of supraventricular reentrant tachyarrhythmias including atrial fibrillation. This report reviews the pharmacology, electrophysiolog efficacy and safety of this agent.