Leukotriene receptor antagonists exert complementary effects to corticosteroids in modifying the inflammatory response in asthma. Löfdahl and colleagues investigated whether use of the leukotriene receptor antagonist montelukast allows a reduction in the dosage of inhaled corticosteroids in patients with asthma.

The double-blind, placebo-controlled study included 226 clinically stable patients who were seen at 23 academic medical centers or large group practices in the United States, Canada and Europe. Patients in the study required a twice-daily dose of inhaled corticosteroids. Following a placebo run-in period to establish the minimum dosage of inhaled corticosteroid necessary to maintain symptom stability, patients were randomly assigned to receive 10 mg of montelukast or placebo at bedtime. Treatment lasted 12 weeks. At each two-week visit, the dosage of the inhaled corticosteroid was adjusted on the basis of a composite score derived from the degree of symptoms, the need for beta-agonist therapy and the forced expiratory volume in one second (FEV₁).

Each group contained 113 patients, but one patient in the montelukast group could not be included in the analysis. The two groups were comparable. During the run-in period, the mean dosage of inhaled corticosteroid for the entire study group was reduced 37 percent. By the end of the study, the inhaled corticosteroid dosage in the montelukast group had declined a mean of 47 percent, compared with a mean decline of 30 percent in the placebo group. In the montelukast group, 70 (62 percent) of the 112 patients were able to reduce the inhaled corticosteroid dosage by 50 percent or more, and 45 (40 percent) of the patients were able to completely taper off inhaled steroids. In the placebo group, the inhaled corticosteroid dosage was reduced by at least 50 percent in 57 (50 percent) of the 113 patients. Thirty-three (29 percent) of the placebo group had completely tapered off the inhaled corticosteroid by the end of the study. No reduction in the use of inhaled corticosteroids occurred in 31 (28 percent) of the montelukast group and in 41 (36 percent) of the placebo group. No differences occurred between the two groups in the frequency of adverse effects.

The authors conclude that montelukast allows a significant reduction in the dose of inhaled corticosteroids in patients with asthma. In addition, they note that the run-in period demonstrated that patients commonly take higher than required dosages of inhaled corticosteroids.