Asthma is a chronic inflammatory condition of the small airways that can be treated with inhaled corticosteroids. However, some patients do not respond to low-dose inhaled corticosteroids and require other treatment options. Recent studies have shown that the addition of a long-acting beta₂ agonist to lowdose inhaled corticosteroid therapy provides the same or better clinical outcomes compared with higher dosages of inhaled corticosteroids alone. In addition, leukotriene receptor antagonists provide anti-inflammatory and bronchodilator activity and have proved beneficial in the management of asthma. However, recent studies did not evaluate the effect of these agents on bronchial hyperresponsiveness or airway inflammation. Wilson and colleagues assessed the effectiveness of adding a leukotriene receptor antagonist and a long-acting beta₂ agonist as secondline therapy in the management of asthma.

Participants in the study had persistent asthma symptoms that were not controlled with inhaled corticosteroid therapy. The study was a placebo-controlled, single-blind, double-dummy, crossover design. Patients were randomized to receive oral montelukast, in a dosage of 10 mg once daily and a placebo inhaler twice daily, or salmeterol, in a dosage of 50 mg twice daily and a placebo tablet once daily. Each treatment phase lasted two weeks, with one-week placebo periods. Patients continued using their usual maintenance dosage of inhaled corticosteroid treatment throughout the study. Measurements performed included adenosine monophosphate bronchial challenge, blood eosinophil count, exhaled nitric oxide and lung function, with testing after each placebo period and after the first and last doses of each active treatment. Patients recorded their peak expiratory flow (PEF), asthma symptoms and rescue bronchodilator requirement (RES) twice daily.

After the two-week treatment period, montelukast and salmeterol significantly improved the PEF and RES measurements compared with placebo and reduced the number of symptoms reported by the study participants. The only significant difference between the two agents was that montelukast reduced the blood eosinophil count more than salmeterol and had a greater impact on the adenosine monophosphate challenge test.

The authors conclude that both montelukast and salmeterol are useful adjuvant therapies for asthma not controlled with inhaled corticosteroids. Montelukast did provide more anti-inflammatory effect than salmeterol in this short-term study, but long-term studies are needed to determine if this effect has any positive clinical outcomes.