Background: The effectiveness of inhaled glucocorticoids in the treatment of asthma is well documented; however, times to onset and maximal treatment effects of these agents have been poorly described.
Objective: We sought to determine the time to onset of effect and the time to the best observed effect of inhaled fluticasone propionate (FP) in patients with asthma.
Methods: Data from 8 randomized, double-blind, placebo-controlled clinical trials of at least 8 weeks' duration were analyzed. Corticosteroid-naive patients (n = 1461) were treated with either FP (25 micrograms to 500 micrograms) or placebo twice daily. Efficacy evaluations included morning peak expiratory flow (PEF), asthma symptom scores, supplemental albuterol use, and FEV1.
Results: Statistically significant improvements in PEF, asthma symptom scores, and supplemental albuterol use were observed beginning on day 1 of treatment in the FP group versus the placebo group (P <.001); significant increases in FEV1 were observed at the first measurement at week 1 (P <.001). The best observed effect occurred within 3 weeks of the start of FP treatment for PEF (+36 L/min) and FEV1 (+0.52 L) and within 2 weeks for reduction in supplemental albuterol use and asthma symptom scores. Patients with the most severe airflow obstruction had the greatest change in PEF (+56 L/min) and fastest time to 50% of best observed effect (3 days) compared with patients with mild or moderate airflow obstruction; however, time to best observed effect was similar in the 3 groups (20 to 27 days).
Conclusion: In patients with asthma, the onset of significant benefit of FP on PEF, symptoms, and rescue albuterol use occurred within 1 day of the start of therapy. FEV1 improved within 1 week of the start of therapy (the first measurement after randomization). There was no effect of sex, age, or dose of FP on the time to response. The best observed response in PEF varies with the degree of baseline airflow obstruction; however, the degree of airflow obstruction has no effect on the time to best observed response.