EFFECT OF NEDOCROMIL SODIUM ON SPECIFIC MEDIATOR-INDUCED AND ANTIGEN-INDUCED AIRWAY RESPONSES IN ALLERGIC SHEEP

This study evaluated the airway effects of nedocromil sodium in the sh eep model of allergic bronchoconstriction. Nedocromil sodium provided statistically significant protection against both reflex- and mediator -induced bronchoconstriction in allergic sheep as assessed by bronchia l responses to inhaled bradykinin and platelet-activating factor, resp ectively. When administered before antigen challenge, nedocromil sodiu m blocked both the immediate and late asthmatic response and prevented the subsequent increase in airway hyperresponsiveness. The protective effect of nedocromil sodium against the antigen-induced late response was associated with a significant decrease in the number of airway eo sinophils measured by bronchoalveolar lavage. Although nedocromil sodi um has no direct bronchodilatory activity, it prevented antigen-induce d contractions in sheep tracheal smooth muscle in vitro. These results suggest that nedocromil sodium is active in the sheep model of allerg ic bronchoconstriction and may be useful in the treatment of reversibl e obstructive airway disease in human beings.