Study objective: Several studies have demonstrated the superiority of salmeterol and formoterol to either regular treatment with albuterol or placebo. However, to date there have been no trials comparing the efficacy of salmeterol and formoterol in patients with severe asthma.
Design: We undertook a randomized, placebo-controlled, crossover study to compare 4 weeks of treatment with inhaled formoterol (12 μg twice daily) or salmeterol (50 μg twice daily) in patients with severe asthma whose conditions were not being adequately controlled by therapy with high doses of inhaled corticosteroids (ie, ≥ 1,500 μg daily) or with regular oral corticosteroid treatment. Morning pretreatment peak expiratory flow (PEF) during the last 14 days of the treatment period was the primary outcome variable. Patients recorded morning and evening pretreatment PEF, daytime and nighttime symptom scores, and any use of rescue medication. Spirometry and bronchial reversibility were performed after each treatment.
Results: Forty-two nonsmoking patients (29 women; mean age, 45 ± 2 years; mean [± SEM] FEV1, 61.8 ± 3.4% of predicted) took part in the trial, and 27 patients completed the trial. The mean morning PEF was greater in patients receiving formoterol (mean increase, 14.4 L/min; 95% confidence interval [CI]. 0.2 to 28.6) or salmeterol (mean increase, 14.8 L/min; 95% CI, 0.5 to 29.1) compared with those receiving placebo, but there was no difference between these treatments. There were no significant treatment effects for any of the secondary outcome variables (ie, FEV1, FVC, mean evening PEF, mean daytime symptom score, or nighttime symptom score).
Conclusion: We conclude that the long-acting β2-agonists salmeterol and formoterol improve morning PEF in patients with severe asthma, but that there is no difference in efficacy between the two drugs.