Effect of differing doses of inhaled budesonide on markers ofairway inflammation in patients with mild asthma

摘要

BACKGROUND—It is desirable to prescribe the minimal effective dose of inhaled steroids to control asthma. To ensure that inflammation is suppressed whilst using the lowest possible dose, a sensitive and specific method for assessing airway inflammation is needed.
METHODS—The usefulness of exhaled nitric oxide (NO), sputum eosinophils, and methacholine airway responsiveness (PC20) for monitoring airway inflammatory changes following four weeks of treatment with an inhaled corticosteroid (budesonide via Turbohaler) were compared. Mild stable steroid naive asthmatic subjects were randomised into two double blind, placebo controlled studies. The first was a parallel group study involving three groups receiving either 100 µg/day budesonide (n = 8), 400 µg/day budesonide (n = 7), or a matched placebo (n = 6). The second was a crossover study involving 10 subjects randomised to receive 1600 µg budesonide or placebo. The groups were matched with respect to age, PC20, baseline FEV1 (% predicted), exhaled NO, and sputum eosinophilia.
RESULTS—There were significant improvements in FEV1 following 400 µg and 1600 µg budesonide (11.3% and 6.5%, respectively, p<0.05). Thiswas accompanied by significant reductions in eosinophil numbers ininduced sputum (0.7 and 0.9 fold, p<0.05). However, levels of exhaledNO were reduced following each budesonide dose while PC20was improved only with 1600 µg budesonide. These results suggestthat exhaled NO and PC20 may not reflect the control of airway inflammation as accurately as the number of eosinophils insputum. There were dose dependent changes in exhaled NO, sputum eosinophils, and PC20 to inhaled budesonide but a plateauresponse of exhaled NO was found at a dose of 400 µg daily.
CONCLUSION—Monitoringthe number of eosinophils in induced sputum may be the most accurateguide to establish the minimum dose of inhaled steroids needed tocontrol inflammation. This, however, requires further studies involvinga larger number of patients.