Leukotriene Modifiers

Most asthma controllers are inhaled — montelukast is the oral one taken at bedtime, and its unique FDA boxed warning has nothing to do with the lungs.

Leukotrienes are inflammatory mediators released from mast cells and eosinophils during the allergic cascade. They cause bronchoconstriction, mucus secretion, and airway edema. Montelukast (Singulair) blocks leukotriene receptors (CysLT1), preventing this downstream inflammation. It does NOT bronchodilate acutely — it is a long-term controller used for prophylaxis of mild persistent asthma and exercise-induced bronchospasm, often as add-on therapy when inhaled corticosteroids alone are insufficient. It also treats allergic rhinitis. Montelukast is taken once daily in the evening (bedtime for asthma control). The dose form matters: chewable tablets for pediatric clients ages 2–14, granules for ages 6 months–23 months. The FDA boxed warning (2020) addresses serious neuropsychiatric events — mood changes, agitation, depression, suicidal ideation, and hallucinations. Nurses must assess baseline mental health status and teach families to report any behavioral or mood changes immediately. Montelukast is NOT a rescue medication and must never replace a short-acting bronchodilator during an acute attack.

Key Distinctions

Don't confuse montelukast (leukotriene receptor antagonist, oral, controller) with zileuton (5-lipoxygenase inhibitor, requires liver function monitoring — rarely tested but commonly confused). Students mix up montelukast with inhaled corticosteroids — both are controllers, but montelukast works on the leukotriene pathway, not broadly on inflammation, and carries neuropsychiatric risk rather than oral candidiasis risk. Never use montelukast as a rescue drug during acute bronchospasm.

Clinical Pearl

Bedtime, by mouth, and watch the brain — montelukast's three signature features are evening dosing, oral route, and neuropsychiatric monitoring.