Effects of zafirlukast upon clinical, physiologic, and inflammatory responses to natural cat allergen exposure

Background: Leukotriene receptor antagonists have been shown to attenuate p hysiologic changes in the upper and lower airways induced by allergen chall enge. However, it is unknown whether these drugs modulate airway inflammati on after exposure to allergen in a natural setting. Objective: To determine the effects of the oral leukotriene receptor antago nist zafirlukast upon symptoms, changes in pulmonary function, and indices of inflammation in the upper and lower airways induced by natural exposure to cats. Methods: Zafirlukast, 20 mg twice daily, or placebo was administered to 18 cat-allergic asthmatic patients in this randomized, double-blind, crossover study. Cat room challenges were performed after a 1-week period of each tr eatment. Upper and lower airway symptoms were measured and spirometry perfo rmed before and at regular intervals during each challenge. Nasal lavage an d sputum induction were performed 24 hours before and after each challenge. Results: Zafirlukast significantly improved the prechallenge baseline FEV1 (P = 0.001) and attenuated the decrease in FEV1 induced by cat challenge (P = 0.019). Zafirlukast also significantly reduced lower airway symptoms ass ociated with cat challenge (P = 0.005) but had no effects on nasal symptoms . Although zafirlukast did not significantly differ from placebo in its eff ects on sputum inflammatory cells or eosinophil cationic protein, it signif icantly reduced the absolute counts of total white cells, lymphocytes, neut rophils, and basophils in nasal lavage fluid. Conclusions: Zafirlukast, 20 mg twice daily for 1 week, demonstrated a sign ificant protective effect on symptoms of asthma and alterations in pulmonar y function induced by natural cat exposure, whereas nasal symptoms and mark ers of sputum inflammation were not affected by the medication.