Antiarrhythmic, electrophysiologic and hemodynamic effects of lorcainide.

Lorcainide hydrochloride or N-(4-chlorophenyl)-N-[1-(1-methyl-ethyl)-4-piperidinyl]benzeneacetamide mono-hydrochloride (R 15889) is a new anti-arrhythmic drug. Studies in dogs show that lorcainide is effective against post-infarction and ouabain-induced ventricular arrhythmias, and abolishes acetylcholine and aconitine-induced atrial fibrillation; it elevates the threshold of electrically induced ventricular fibrillation. In isolated dog and cow Purkinje fibers, in dog ventricular and in guinea-pig auricular muscle preparations, lorcainide decreases the rate of rise of the transmembrane action potential, the conduction velocity and spontaneous activity. It prolongs the refractory period of isolated Purkpinje and ventricular muscle preparations, and the functional refractory period of the AV node in the guinea-pig heart. It has no effect on Ca mediated electrical activity. Isometric force measurements in isolated cat papillary muscles and hemodynamic studies in anaesthetized and unanaesthetized dogs indicate that lorcainide moderately decreases myocardial contractility. Side effects observed at large doses are of central origin and include salivation, tremor and vomiting. Intravenous injection induces transient peripheral vasodilatation. Lorcainide is an antiarrhythmic of the local anaesthetic type. It is characterized by a good oral absorption, a long duration of action and a large safety factor.