Anticholinergic bronchodilators such as
tiotropium, a potent long-acting
drug, are central to the symptomatic treatment of
chronic obstructive pulmonary disease. Its role in
asthma treatment has been recently investigated. This review critically evaluates documented evidence of clinical trials and assesses the therapeutic implications of
anticholinergic drugs in
asthma management. So far, the results of 10 Phases II and III randomized controlled trials evaluating the effect of adding
tiotropium to the treatment of mild-to-moderate or severe
asthma have been published. These trials had a duration of 4 to 52 weeks and involved 3368 subjects with mild-to-moderate
asthma and 1019 subjects with severe
asthma [corrected]. Also, 1 systematic review and 6 meta-analyses have appraised the results of published and unpublished trials investigating the role of
tiotropium in
asthma. The results of the trials in mild to moderate
asthma showed that adding
tiotropium to inhaled
corticosteroids (ICSs) was not inferior to adding long-acting β2-agonists (LABAs). In addition, the safety and efficacy of
tiotropium were similar to those of
salmeterol. The results of studies on severe
asthma showed that adding
tiotropium to a treatment with high doses of an ICS plus LABA results in further improvement in lung function, increases the time to the first severe exacerbation of
asthma and to worsening of
asthma, and improves
asthma control. Except for dry mouth, the safety profile of
tiotropium was similar to placebo both in moderate and in severe
asthma. Adding
tiotropium to an ICS or ICS plus LABA improves lung function, symptoms, and
asthma control, and in severe
asthma, it increases the time to exacerbations, with good safety profile. The effect seems independent of baseline characteristics such as age, level of bronchial obstruction, smoking status, allergic status, and bronchial reversibility.