Tiotropium versus placebo for chronic obstructive pulmonary disease.

Tiotropium is an anticholinergic agent which has gained widespread acceptance as a once daily maintenance therapy for symptoms and exacerbations of stable chronic obstructive pulmonary disease (COPD). In the past few years there have been several systematic reviews of the efficacy of tiotropium, however, several new trials have compared tiotropium treatment with placebo, including those of a soft mist inhaler, making an update necessary.