Effects of formoterol on exercise tolerance in severely disabled patients with COPD

Abstract

Objective We wished to evaluate the effects of inhaled formoterol, a long-acting beta(2)-adrenergic agonist, on exercise tolerance and dynamic hyperinflation (DH) in severely disabled chronic obstructive pulmonary disease (COPD) patients. Design In a two-period, crossover study, 21 patients with advanced COPD (FEV(1)=38.8+/-11.7% predicted, 16 patients GOLD stages III-IV) were randomly allocated to receive inhaled formoterol fumarate 12 microg twice daily for 14 days followed by placebo for 14 days, or vice versa. Patients performed constant work-rate cardiopulmonary exercise tests to the limit of tolerance (Tlim) on a cycle ergometer: inspiratory capacity (IC) was obtained at rest and each minute during exercise. Baseline and transitional dyspnoea indices (BDI and TDI) were also recorded. Results Eighteen patients completed both treatment periods. Formoterol treatment was associated with an estimated increase of 130 s in Tlim compared with placebo (P=0.052): this corresponded to a 37.8% improvement over placebo (P=0.012). Enhanced exercise tolerance after bronchodilator was associated with diminished DH marked by higher inspiratory reserve and tidal volumes at isotime and exercise cessation (P<0.05). There was no significant difference between formoterol and placebo on exercise dyspnoea ratings; however, all domains of the TDI improved (P<or=0.02) following formoterol, compared with placebo. Conclusion Inhaled formoterol 12 microg twice daily is effective in ameliorating DH, daily dyspnoea and exercise intolerance even in patients with advanced COPD.