Studies on 1-(o-cyclopropylphenoxy)-3-isopropylamino-2-propanol, a new β-adrenergic blocking drug

Abstract

The beta-adrenergic blocking action, the effects on resting cardiovascular parameters and the anti-arrhythmic properties of 1-(o-cyclopropylphenoxy)-3-isopropylamino-2-propanol hydrochloride (SD 2124-01) were investigated. SD 2124-01 was 6 to 43 times more potent than propranolol in antagonizing the effects of isoproterenol on heart rate, myocardial contractile force, dLVP/dt and diastolic blood pressure. In isolated preparations (guinea pig atria and tracheal chains), it was 7 to 10 times more potent than propranolol. LD 50's of SD 2124-01 and propranolol in mice were not significantly different. At beta-adrenergic blocking doses, SD 2124-01 was devoid of any intrinsic beta sympathomimetic activity and did not depress the resting cardiovascular parameters of chloralose-anesthetized dogs. Simultaneously, SD 2124-01 facilitated ‘auriculoventricular conduction’. At high doses, it reversed ouabain-induced ventricular tachycardia but reversio was then associated with moderate cardiac depression. Thus, SD 2124-01 appears to be, like prinodolol, one of the most potent and least cardiodepressive beta-adrenergic blocking drugs.