Bronchospasmolytic effects of RU 42173.

The bronchodilator properties of RU 42173, a new beta-adrenergic stimulant with an original structure, as a cyclic analogue of an arylethanolamine, have been evaluated on different in vitro and in vivo models and compared with those of salbutamol and isoprenaline. RU 42173 equipotently inhibited histamine-, acetylcholine-, and KCl-induced contractions in isolated guinea pig trachea or small bronchus and in isolated human bronchus. When administered to guinea pigs by the IV or aerosol route, RU 42173 dose-dependently inhibited bronchospasm induced by histamine, acetylcholine, and methacholine. It also inhibited PAF-induced bronchoconstriction and PAF-induced hyperreactivity to histamine. Moreover, RU 42173 had a rapid onset and prolonged duration of action. The potency of RU 42173 was similar to that of salbutamol.