Effects of replacing oxitropium with tiotropium on pulmonary function in patients with COPD: a randomized study

Inhaled bronchodilators are first line drugs in the treatment of chronic obstructive pulmonary disease (COPD). Tiotropium bromide is a recently introduced long-acting anticholinergic agent able to reduce dyspnoea and COPD exacerbations and to improve pulmonary function and quality of life. We designed a study to compare the short-term efficacy of tiotropium bromide with that of oxitropium bromide in improving pulmonary function in patients with COPD.

Eighty patients were randomized either to continue oxitropium 800 mcg/day or to receive tiotropium 18 mcg/day. Seventy-six (39 in the tiotropium and 37 in the oxitropium group) completed the study. Plethysmography was performed at baseline and after 72 h in all patients. The changes in functional parameters in the two groups were compared by the Mann-Whitney U-test.

There were no differences between the two groups regarding age (72.5 vs. 74.2 years), male/female ratio (25/14 vs. 23/14) and pulmonary function at baseline. The changes in spirometric parameters were significantly greater in tiotropium- than in oxitropium-treated patients: mean forced expiratory volume in 1s (FEV(1)) increased significantly by 15% vs. 3% (P=0.017), mean FVC by 10.5% vs. 2.2% (P=0.044), and FEF 25, 50, and 75 by 34% vs. 14% (P<0.05), 33% vs. 7% (P<0.05), and 50% vs. 6% (P<0.0001), respectively; mean FRC and RV decreased nonsignificantly by 7.5% and 10% with tiotropium vs. 4.3% and 6.5% with oxitropium, respectively.

The replacement of oxitropium with tiotropium significantly increases pulmonary function in patients with COPD. The improvement involves also small airways that have not been investigated thus far.