Cumulative dose-response curves for early evaluation of bronchodilator drugs.

SM 220, a new beta-receptor agonist, was compared with terbutaline by construction of dose response curves for FEV1, heart rate and blood pressure. The pharmacological profile of SM 220 after preclinical studies was that of a potent and highly selective bronchodilator. In this study the beta2 selectivity of SM 220 was poorer than that of terbutaline. The importance of commencing clinical evaluation of bronchodilators with a dose-response test is stressed.