Background: Chronic obstructive pulmonary disease (COPD) is a growing public health problem that has increased in recent years. It similarly affects men and women, especially those who smoke. The goals of COPD pharmacotherapy are to improve lung function, reduce symptoms, prevent exacerbations, and improve patients' health status. Bronchodilators are the foundation of treatment for COPD, and the long-acting beta2-agonists formoterol and salmeterol are both indicated for regular use by patients with stable COPD.

Objective: A clinical study was conducted to compare the onset of bronchodilator effects following treatment with formoterol 12 microg administered twice-daily (BID) or salmeterol 50 microg BID. The trial also assessed whether the bronchodilator effects of treatment resulted in significant differences in clinical response.

Methods: This was a randomized, multicenter, open-label, parallel-group study of formoterol 12 microg BID versus salmeterol 50 microg BID, both administered for 28 days. Patients were current or previous smokers aged>or=40 years, with a diagnosis of stable COPD. The primary efficacy variable was change from baseline in forced expiratory volume in 1 s (FEV1) 5 min after drug administration on day 28. Secondary efficacy variables included changes from baseline in the 6-min walk test (6MWT) and rescue medication use. The primary variable was assessed by analysis of covariance, with baseline FEV1 as the covariate.

Results: A total of 270 patients were randomized to formoterol 12 microg BID (n=137) or salmeterol 50 microg BID (n=133). In the intent-to-treat population the least square (LS) mean change from baseline in FEV1 at 5 min postdose on day 28 was 0.13 L in the formoterol group compared with 0.07 L in the salmeterol group (P=0.022). At 30 min postdose on day 28, the LS mean change from baseline in FEV1 was 0.17 L in the formoterol group compared with 0.07 L in the salmeterol group (P<0.001). Similar changes were reported at 60 min postdose (0.19 L for the formoterol group versus 0.13 L for the salmeterol group, P=0.069). Patients in the formoterol group walked longer distances in the 6MWT and used less rescue medication compared with patients in the salmeterol group, although the differences were not statistically significant.

Conclusions: Significantly greater improvements from baseline in FEV1 were observed at 5 and 30 min postdose with formoterol 12 microg compared with salmeterol 50 microg after 28 days of treatment. Numeric improvements in the 6MWT and rescue medication use were also observed with formoterol.