Effects of formoterol inhaled dry powder on exercise performance in chronic obstructive pulmonary disease: a single-center, randomized, double-blind, placebo-controlled, crossover study

Background: Inhaled bronchodilators commonly are used to reduce the work of breathing in patients with chronic obstructive pulmonary disease (COPD). The effects of bronchodilators are assessed in terms of symptom relief and/or improvements in spirometric indices. However, disability in COPD patients also is related to determinants such as exercise tolerance, which cannot be predicted on the basis of respiratory function. The effect of bronchodilators, such as inhaled beta2-agonists, on exercise performance of COPD patients needs to be tested.

Objective: This study investigated the effects of formoterol inhaled dry powder on exercise performance assessed using the shuttle walking test (SWT) in patients with mild to moderate COPD.

Methods: Patients having COPD with mild to moderate airway obstruction performed a pulmonary function test and an SWT before and after inhalation, on 2 consecutive days, of formoterol 12 μg or placebo, given by dry powder inhaler, according to a double-blind, placebo-controlled, crossover study design. Breathlessness was measured using the Borg scale (BS) and a visual analog scale at baseline and after an SWT.

Results: Twenty patients (15 men, 5 women; mean [SD] age, 65.95 [8.32] years) were included in the study. Forced expiratory volume in 1 second (FEV1) (P = 0.009), forced mid-expiratory flow (FEF25-75) (P = 0.011), and SWT (P = 0.005) improved significantly more with formoterol than placebo. Breathlessness decreased with formoterol, but the difference compared with placebo was statistically significant only when measured using the BS (P = 0.023). In the pooled placebo and formoterol tests, changes in the SWT were unrelated to changes in FEV1 (r = 0.18) and in FEF25-75 (r = 0.31).

Conclusions: The results of this study showed that formoterol inhaled dry powder significantly improved exercise performance in patients with COPD and that this effect was at least partially independent of achieved bronchodilation. A larger cohort of patients should be studied and a more comprehensive protocol performed to verify whether the increase in exercise tolerance after administration of formoterol is related to a decrease in expiratory flow limitation during exercise and/or to systemic effects of the drug. Another issue to be clarified is whether the improvement in exercise capacity can significantly decrease disability in patients with severe COPD.