Leukotriene receptor antagonist drugs for asthma

Synopsis Leukotriene receptor antagonists (LTRAs — zafirlukast and montelukast) are a new class of oral anti‐asthma medication which target a specific inflammatory pathway not covered by currently available drugs. LTRAs have a combined bronchodilator (“reliever”) as well as anti‐inflammatory (“preventer”) effect. The degree of bronchodilator effect is slower in onset, but partially additive to short‐acting β 2 ‐agonists (onset 1–3 hours, with 10%–20% improvement in lung function). The degree of anti‐inflammatory effect is about equivalent to 400 μg/day of inhaled steroids. Both zafirlukast and montelukast are generally well tolerated, with a side effect profile similar to placebo. Data from clinical trials give Level II evidence that LTRAs: ♦ produce sustained improvement in lung function ♦ reduce requirements for short‐acting reliever medication ♦ improve asthma symptom scores ♦ reduce requirements for inhaled steroidsIndications for the use of LTRAs in asthma include: ♦ mild asthma if there is difficulty using inhaled medication ♦ moderate to severe persistent asthma as an add‐on to currently available inhaled medication ♦ aspirin‐induced asthma ♦ exercise‐induced asthma. Because of heterogeneity in response, the only way to judge efficacy is a therapeutic trial for 4–6 weeks.