MUCOLYTIC ACTIVITY OF AZELASTINE IN MICE AND RATS

The mucolytic activity of azelastine, an antiallergic/antiasthmatic dr ug, in mice and rats was investigated. The oral administration of test compounds 30 min before phenol red i.p. injection stimulated dye secr etion in the trachea of mice. The resulting oral ED50's (mg/kg) were: azelastine, 0.16; salbutamol, 2.5; N-acetylcysteine,61.8;S-Carboxymeth yl-l-cysteine, <100; bromhexine, >100; and potassium iodide, approxima tely 200. In rats, several drugs stimulated secretion of fluorescein s odium (FINa) in the tracheobronchial lumen. The resulting oral ED50's (mg/kg) were: azelastine, 0.33; terbutaline, 0.3; salbutamol, 0.89; an d S-carboxymethyl-l-cysteine, 56.8. Terfenadine and diphenhydramine (1 -10 mg/kg, p.o.) did not stimulate tracheal secretion in rats and mice . The mucolytic activity of azelastine may contribute to its overall e ffectiveness, including antitussive activity in asthmatics. Finally, t his activity seems to be dissociated from its H-1-histamine receptor b locking activity.