Background: The combination of short-acting β2-agonists and anticholinergics in the treatment of COPD has been well documented, but data on combination of long-acting agents are lacking.
Methods: A randomized, open-label, placebo-controlled, three-way crossover study was conducted comparing 2-week treatment periods of tiotropium alone to tiotropium plus formoterol once or twice daily following a 2-week pretreatment period with tiotropium. Lung function (FEV1, FVC, and resting inspiratory capacity [IC]) serially over 24 h was measured in 95 patients with stable COPD at baseline and after 2 weeks of each treatment.
Results: Mean baseline FEV1 was 1.05 L (38% of predicted). There was a circadian variation in FEV1, FVC, and IC at baseline that was maintained during all treatment periods. Average FEV1 (0 to 24 h) improved by 0.08 L with tiotropium, by 0.16 L with tiotropium plus formoterol once daily, and by 0.20 L with tiotropium plus formoterol twice daily (p < 0.01 for all comparisons). Compared with tiotropium alone, add-on formoterol in the morning produced improvement in FEV1, FVC, and IC for > 12 h. The second add-on dose of formoterol in the evening caused further improvement in FEV1 for 12 h, but in FVC and IC for < 12 h. Peak increase in FEV1 was 0.23 L (22% of baseline) with tiotropium and 0.39 L (37% of baseline) with tiotropium plus formoterol (p < 0.0001). Compared with tiotropium alone, add-on formoterol once and twice daily reduced the use of rescue salbutamol during the daytime (p < 0.01) and with add-on formoterol twice daily also during the nighttime (p < 0.05). The combination of tiotropium and formoterol was well tolerated.
Conclusion: In the treatment of COPD, there is benefit from adding formoterol once or twice daily to tiotropium once daily in terms of improvement in airflow obstruction, resting hyperinflation, and the use of rescue salbutamol.