Effects of once daily dosing with inhaled budesonide on airway hyperresponsiveness and airway inflammation following repeated low-dose allergen challenge in atopic asthmatics

Background Repeated low-dose allergen challenge increases airway hyperrespo nsiveness and sputum eosinophils in atopic asthmatics. Inhaled corticostero ids attenuate the airway responses to high-dose allergen challenge, but hav e not been evaluated against repeated low dose challenge. Objective This study evaluates the effects of once daily treatments of two doses of inhaled budesonide on airway responses to repeated low-dose allerg en challenge. Methods Eight atopic asthmatics with a dual airway responses to inhaled all ergen were recruited into a randomized, double-blind crossover, placebo-con trolled study. In the mornings of four consecutive days (day 1-day 4), subj ects inhaled budesonide 100 mu g, 400 mu g, or placebo, 30 min before inhal ing a concentration of allergen causing a 5% early fall in FEV1. Airway hyp erresponsiveness to methacholine and sputum eosinophils were measured at ba seline, on the afternoon of day 2, day 4, and 24 h after the last challenge . There was a 1-week washout between each of the three treatment periods. Results The repeated low-dose allergen challenge induced increases in the p ercentage sputum eosinophils from 2.0 +/- 0.7% at baseline to 16.6 +/- 7.1% on day 4 (P = 0.002), and this effect was reduced by once daily budesonide 100 mu g to 5.6 +/- 1.8% (P = 0.01) and by once daily budesonide 400 mu g to 3.1 +/- 0.9% (P=0.004). Also, the allergen-induced methacholine airway h yperresponsiveness which occurred by day 4 (P=0.03) of the repeated low dos e challenge was inhibited by budesonide 400 mu g (P = 0.017). Conclusion Both budesonide 100 mu g and 400 mu g inhaled once daily signifi cantly reduces allergen-induced sputum eosinophilia after repeated low dose challenge; however, only the higher dose also attenuates the allergen-indu ced airway hyperresponsiveness.