Azelastine inhibits bronchial hyperreactivity to acetylcholine in guinea pigs.

Contractile responses to acetylcholine were measured using isolated tracheae obtained from actively sensitized guinea pigs 0.5, 1, 5, 20, 24, 48 and 72 h after antigen challenge. Tracheal contractions to acetylcholine and to histamine were significantly increased 20 h but not 0.5, 1, 5, 24, 48 and 72 h after antigen challenge indicating bronchial hyperreactivity. When animals were pretreated with azelastine and then exposed to antigen challenge, concentration-response curve to acetylcholine did not differ from that obtained in control (non-challenged) tracheae. It is likely that azelastine is able to inhibit bronchial hyperresponsiveness to chemical mediators of bronchial asthma.