Effects of equiblocking doses of nadolol and propranolol on left ventricular performance

Abstract

Nadolol, a recently developed noncardioselective β-adrenergic blocker, has the potential advantages of a longer oral half-life (t½) than propranolol and, in animal studies, markedly fewer direct myocardial depressant effects. Neither the relative intravenous potency of nadolol and propranolol nor the comparative effects of the 2 drugs on left ventricular performance has been studied in man. We compared equiblocking intravenous doses of nadolol and propranolol in 10 subjects with ischemic wall-motion disorders. Nadolol was on the average 6.2 times as potent on a milligram-for-milligram basis. Both drugs decreased resting heart rate (p < 0.02) and produced small rises in both mean pulmonary artery (p < 0.03) and mean pulmonary artery wedge (p < 0.03) pressures without significantly reducing the cardiac output. Both drugs also produced depression of the radionuclide ejection fraction (p < 0.002). There were no significant differences between the effects of the 2 drugs on any of the aforementioned variables. Thus, the effects of nadolol on left ventricular performances are similar to those of propranolol. Because of its long oral t½, nadolol may prove to be a clinically useful drug.