leukotriene antagonist

A leukotriene antagonist blocks one of the inflammatory chemicals the body releases in allergy and asthma. Leukotrienes are signalling molecules that tighten airways, leak fluid and recruit inflammatory cells; this drug intercepts their message so the airways stay calmer.

The common agents montelukast and zafirlukast are cysteinyl leukotriene receptor (CysLT1) antagonists: they sit on the receptor that leukotrienes would otherwise activate, reducing bronchoconstriction, mucus and inflammation. They are taken by mouth, which suits people who struggle with inhalers, and are particularly helpful in exercise-induced symptoms and in asthma accompanied by allergic rhinitis. A different drug, zileuton, instead inhibits the enzyme that makes leukotrienes.

Leukotriene antagonists are add-on or alternative controllers, generally less effective than inhaled corticosteroids for most asthma. They are usually well tolerated, but montelukast carries a warning about neuropsychiatric effects such as mood changes, sleep disturbance and, rarely, suicidal thoughts, so any such changes should prompt review.