ANTIARRHYTHMIC ACTIVITY OF BUNOLOL, A NEW BETA ADRENERGIC BLOCKING AGENT

¹ Warner-Lambert Research Institute, Morris Plains, New Jersey

Bunolol, a potent beta adrenergic receptor blocking agent, was evaluated in dogs for activity against the arrhyth. mias induced by epinephrine, ouabain and coronary artery ligation. Bunolol prevented epinephrine-induced ventricular tachycardias in both normal anesthetized and epinephrine-sensitive, coronary-ligated, unanesthetized dogs. Bunolol was considerably less effective than propranolol against ouabain-induced ventricular tachycardias in anesthetized and conscious dogs and was ineffective against the ventricular arrhythmiaa in dogs 24 hours after coronary ligation. In the ouabain-intoxicated animals, bunolol consistently slowed ventricular rates and frequently caused a shift in ectopic pacemaker site(s), exposed coupled rhythms and brought about transient conversions to normal sinus rhythm. In the coronary-ligated dogs, bunolol caused moderate reductions in the total arrhythmic rate. At a concentration of 3 x 10^-3 M bunolol, unlike propranolol, had no significant effect on the monophasic action potentials generated in the frog isolated sciatic nerve preparation.