Abstract
A cardio-selective beta-adrenergic blocking agent (I.C.I. 50172), which has been studied both in normal subjects and in patients with angina pectoris during and after a standardized work test, produced a significant increase in the exercise tolerance of the patients. These favourable effects are comparable with those of propranolol. One patient with severe bronchial asthma and coronary insufficiency treated with I.C.I. 50172 improved and his respiratory function was not impaired.