Long-acting muscarinic antagonists (LAMA) have been shown to reduce exacerbations of chronic obstructive pulmonary disease (COPD) and are now being considered for patients with uncontrolled asthma as add-on treatment. A review in the Cochrane Library evaluated eight studies on the safety and efficacy of adding LAMA to inhaled corticosteroids (ICS) compared to long-acting beta2-agonists (LABA) with ICS for adults with poorly controlled asthma.

Eight studies were located for the review and most compared tiotropium to salmeterol when added to medium doses of ICS. No differences were seen in exacerbations between the two add-ons but the evidence was inconsistent and few severe adverse events and exacerbations requiring hospitalization were reported. There were slightly lower scores with LAMA on quality of life and asthma control but these were not clinically significant and the uptick in adverse events with LAMA was not statistically significant. However, LAMA was associated with some improvement in lung function compared to LABA; it is unclear if the difference was clinically significant.

Based on this evidence, the authors do not currently support substituting LAMA for LABA as add-on therapy for patients with asthma uncontrolled with ICS alone.