Comparison of powder and aerosol formulations of salmeterol in the treatment of asthma

Background: The efficacy and safety of the aerosol metered-dose inhaler (MD I) formulation of salmeterol for asthma symptoms have been established. Rec ently, salmeterol has been introduced as a micronized powder formulation ad ministered via a breath-activated multidose powder inhaler (Diskus). Objective: A multicenter, randomized, double-blind, double-dummy, parallel- group, placebo-controlled study involving 498 adolescents and adults with m ild-to-moderate asthma was conducted to compare the efficacy and safety of salmeterol powder 50 mu g twice daily via Diskus, salmeterol aerosol 42 mu g twice daily via MDI, and placebo. Methods: Patients were randomized to one of the three treatment groups for 12 weeks. Efficacy was assessed by serial measurements of forced expiratory volume in one second (FEV,) over 12 hours, daily peak expiratory flow (PEF ), self-rated asthma symptom scores, nighttime awakenings, and supplemental albuterol use. Safety of each treatment was evaluated by monitoring vital signs, electrocardiograms, Holter monitoring, and occurrence of adverse eve nts. Results: As compared with placebo, both salmeterol powder and aerosol produ ced significant improvement in FEV, and PEF and decreased nighttime awakeni ngs and supplemental albuterol use. There were no significant differences i n the efficacy of the two salmeterol formulations. The magnitude of improve ment in pulmonary function was undiminished over the 12-week study. Both fo rmulations of salmeterol were well tolerated, with safety profiles not sign ificantly different from placebo. Conclusion: Results of this study indicate that salmeterol, administered ei ther as a powder 50 mu g twice daily via Diskus or as an aerosol 42 mu g tw ice daily via MDI, produces clinically significant and comparable improveme nt in pulmonary function and is well tolerated in patients with mild-to-mod erate persistent asthma.