Asthma management guidelines emphasize the importance of effective treatment to achieve and maintain control of asthma. However, despite widely available and effective treatments, achieving control of asthma is still an unmet need for many patients. Adding a second bronchodilator with a different mechanism of action for the treatment of uncontrolled asthma can be a suitable therapeutic approach. This review focuses on the role of long-acting muscarinic antagonists, particularly tiotropium, in the treatment of asthma.
A number of studies have evaluated the efficacy and safety of tiotropium in asthma patients whose disease is poorly controlled with inhaled corticosteroids (ICSs) with or without long-acting β2-agonists (LABAs). The effect on several clinical and lung function variables of adding tiotropium to an ICS is greater than doubling the dose of the latter and is not inferior to the addition of a LABA (salmeterol). Studies assessing the role of tiotropium as add-on therapy to ICS combined with a LABA have shown modest but clinically significant and dose-dependent improvements in forced expiratory volume in 1 second, as well as a decrease in the risk of exacerbations. In addition, time to the next episode is longer, particularly in patients who experience severe exacerbations.
In conclusion, tiotropium proved noninferior to salmeterol and superior to placebo in patients with moderate-severe asthma who were not adequately controlled using ICSs or ICSs combined with a LABA. The major benefits are the increase in lung function and, in the case of severe asthma, the reduction in the frequency of exacerbations. In patients with asthma, tiotropium is usually well tolerated, and no potential safety signals have been observed.

Key words: Asthma treatment. Anticholinergics. Bronchodilators. Tiotropium.