A potent β-AR antagonist; selective for β1-ARs over β2-ARs (Kis = 25 and 480 nM, respectively in S49 cells overexpressing the human receptors); inhibits isoproterenol-induced increases in heart rate in guinea pigs; inhibits isoproterenol-induced increases in heart rate and myocardial contractility in conscious dogs (0.3 mg/kg); decreases blood pressure and heart rate in SHRs (7.5 mg/kg twice per day over 19 weeks),