Montelukast sodium is a leukotriene receptor antagonist recently labeled by the U.S. Food and Drug Association for oral prophylaxis and ongoing treatment of asthma in adults and in children who are at least six years old. The previously released leukotrienes, zileuton and zafirlukast, are not labeled for use in children younger than 12 years. Drugs in the leukotriene modulator class decrease eosinophil migration, mucus production and airway wall edema. Consultants for the Medical Letter on Drugs and Therapeutics reviewed the current data on the leukotriene antagonists.

One double-blind, 12-week trial in adults with intermittent or persistent asthma indicated that 10 mg of montelukast taken at bedtime improved the morning forced expiratory volume in one second (FEV₁) better than placebo. Use of montelukast also decreased nocturnal awakenings from asthma and decreased use of a short-acting beta agonist inhaler by 25 percent compared with a 10 percent decrease with placebo. The beneficial effects were near maximum within 24 hours after the first dose and were maintained for the course of the trial. An eight-week trial demonstrated similar beneficial results. Montelukast is not recommended for use alone as prophylaxis or treatment of exercise-induced bronchospasm.

In a 12-week trial, 10 mg of montelukast taken daily was less effective than inhaled beclomethasone, 200 μg twice daily, in increasing FEV₁ in patients with moderate asthma. In a study of patients whose asthma was not adequately controlled with inhaled beclomethasone, the addition of montelukast proved more effective than the addition of placebo in improving lung function and decreasing symptoms. Adults with asthma that was well controlled with inhaled corticosteroids were able to decrease their corticosteroid dosage by 47 percent, compared with a 30 percent reduction with placebo. Furthermore, the combination of inhaled or oral corticosteroids and montelukast was shown to increase the FEV₁ by 8.5 percent compared with a 1.7 percent decrease with placebo.

Montelukast is rapidly absorbed from the gastrointestinal tract, reaches a peak in three to four hours and is excreted mainly in bile. Hepatotoxicity (reported with the use of zileuton) and Churg-Strauss vasculitis (reported with the use of zafirlukast) have not been reported with the use of montelukast. Use of higher-than-recommended dosages of montelukast does not appear to increase the incidence of adverse effects. In short-term studies, the frequency of adverse events with montelukast is similar to that of placebo. Montelukast appears to have fewer drug interactions than zafirlukast because it does not inhibit CYP-450 enzymes, so theophylline, warfarin, prednisone, estrogens or progestins may be used concurrently.

Montelukast is available in 10-mg tablets and 5-mg chewable tablets, which both carry a wholesale cost of $67 for a 30-day supply, according to Drug Topics Red Book. The recommended dosage is 5 mg in children ages six to 14 years and 10 mg in adults, taken daily in the evening without regard to food.

Montelukast is modestly effective in controlling mild to moderate persistent asthma and is approved for use in children. It is less effective than inhaled corticosteroids, but the combination of the two drugs can allow the patient to decrease the corticosteroid dosage by almost 50 percent. It is more convenient and has fewer drug reactions than zafirlukast or zileuton.