Anti-arrhythmic action of nadolol, a beta-adrenergic receptor blocking agent

The anti-arrhythmic action of 2,3-cis-1,2,3,4-tetrahydro-5-[(2-hydroxy-3-tert-butylamino)propoxy]2,3-naphthalenediol (nadolol) was evaluated and compared with that of propranolol in several experimental models of cardiac arrhythmias. Both nadolol and propranolol antagonized isoproterenol-induced tachycardia and ouabain-induced arrhythmias in cats, antagonized coronary artery ligation-induced ventricular fibrillation and suppressed ventricular ectopic activity during vagal stimulation in dogs. In contrast to propranolol, nadolol was considerably weaker in suppressing existing digoxin-induced arrhythmias, lacked local anesthetic activity and did not depress the heart in dogs. Because of these findings, it is concluded that the anti-arrhythmic activity of nadolol is apparently related to blockade of beta-adrenergic receptors.