CARDIOVASCULAR EFFECTS OF PRENALTEROL (H133-22) IN NORMAL MAN

1 Prenalterol, (S‐(‐)‐1‐(4 hydroxyphenoxy)‐3‐isopropylaminopropanol‐2 hydrochloride) a cardio‐selective beta‐adrenergic receptor agonist, was infused intravenously into six normal male volunteers to determine the cardiovascular effects of this drug. 2 On different occasions, each volunteer received a placebo infusion, an infusion of 0.5 mg prenalterol and an infusion of 1 mg prenalterol. Cardiac output (impedance cardiography), arterial pressure (sphygmomanometry), heart rate and ECG were measured throughout. 3 Prenalterol produced a statistically significant increase in cardiac output and at the end of the infusion this increase was 24% with 0.5 mg and 29% with 1 mg, mainly due to an increase in stroke volume (18% and 17%) with a lesser change in heart rate (+2 and +7 beats/min). Pulse pressure increased but mean arterial pressure showed little change. Peripheral resistance fell by 18% and 20%. As indicated by systolic time indices myocardial contractility increased. 4 Prenalterol at plasma concentrations in excess of 20 nmol l‐1 produced significant inotropic effects but did not markedly increase heart rate at concentrations of 60 nmol l‐1. 1979 The British Pharmacological Society