Efficacy of anticholinergic drugs in asthma

Although bronchial hyperresponsiveness to cholinergic agents is a main feature of asthma, the role of anticholinergic drugs in chronic asthma management has been largely underestimated. Several single-dose studies comparing acute bronchodilation induced by ipratropium bromide with salbutamol have shown that salbutamol was more effective than ipratropium in asthma treatment. Recently, tiotropium has been studied in asthma, when added to low-dose inhaled corticosteroids in unselected moderate asthmatics or in patients with uncontrolled asthma, or patients with chronic obstructive pulmonary disease and history of asthma. Later, studies on patients with Arg/Arg beta(2)-receptor polymorphism demonstrated a similar efficacy of tiotropium in comparison with salmeterol when both were added to low-dose inhaled corticosteroids. Further long-term studies are currently in progress, for the evaluation of the efficacy of tiotropium on clinical asthma control, and on the rate and severity of asthma exacerbations, as well as the potential modification of inflammatory mechanisms and varying efficacy in specific asthma phenotypes (such as smoking asthmatics).