ANTIARRHYTHMIC ACTIONS OF TWO NEW BETA ADRENERGIC BLOCKING AGENTS, Kö 1313 AND Kö 1366

¹ Cardiovascular Pharmacology Section, Wyeth Laboratories, Inc., Radnor, Pennsylvania

The effects of two new beta adrenergic blocking substances, Kö 1313 and 1366, on the cardiac conduction system and on experimental arrhythmias, were compared to those produced by propranolol. The three compounds depressed atrioventricular conduction, prolonged ventricular refractory period, reduced maximal atrial following frequency and increased the threshold for electrically induced ventricular fibrillation. Epinephrine-hydrocarbon and ouabain arrhythmias were readily antagonized, but all three agents were less effective in suppressing arrhythmias due to aconitine and coronary occlusion. In many respects, propranolol, Kö 1313 and 1366 resembled each other closely although quantitative differences were frequently evident.