Effect of azelastine on microviscosity of bronchial lavage fluid obtained from actively sensitized and challenged guinea pigs.

Fluorescence polarisation technique was adapted to measure microviscosity in the bronchoalveolar lavage fluid (BAL) of guinea pigs. In sensitized guinea pigs, 20 hours after antigen challenge, the microviscosity of BAL was increased by 86%, suggesting that antigen-induced bronchospasm is followed by inflammatory events. Pretreatment with azelastine (3 mg/kg, p.o., 2 hours prior to antigen challenge) tended to normalize microviscosity in the bronchoalveolar lavage fluid obtained from challenged guinea pigs. The present results suggest that azelastine inhibits the increase of microviscosity of BAL, a symptom of the late phase reactions.