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 sheep model of allergic bronchoconstriction. Nedocromil sodium provided statistically significant protection against both reflex- and mediator-induced bronchoconstriction in allergic sheep as assessed by bronchial responses to inhaled bradykinin and platelet-activating factor, respectively. When administered before antigen challenge, nedocromil sodium 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 eosinophils measured by bronchoalveolar lavage. Although nedocromil sodium has no direct bronchodilatory activity, it prevented antigen-induced contractions in sheep tracheal smooth muscle in vitro. These results suggest that nedocromil sodium is active in the sheep model of allergic bronchoconstriction and may be useful in the treatment of reversible obstructive airway disease in human beings.