Montelukast Arrow Lab (Montelukast)

Montelukast is a leukotriene receptor antagonist used to treat conditions mediated by leukotrienes.

• Asthma: improves long‑term control of symptoms and reduces exacerbations.
• Allergic rhinitis: alleviates nasal congestion, sneezing and itching.
• Exercise‑induced bronchoconstriction: prevents airway narrowing triggered by physical activity.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1, preventing leukotriene D4 and related mediators from binding. By inhibiting this pathway, it reduces bronchial smooth‑muscle contraction, vascular permeability, mucus secretion and inflammatory cell recruitment that contribute to airway narrowing and allergic inflammation. The antagonism is reversible and specific, allowing normal leukotriene functions elsewhere while attenuating the inflammatory response in the respiratory tract.

Montelukast may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache
• Abdominal pain
• Cough
• Sore throat
• Nausea
• Dizziness

Serious or Rare Side Effects

• Allergic reactions such as rash or angioedema
• Neuropsychiatric events including agitation, depression or suicidal thoughts
• Elevated liver enzymes
• Severe skin reactions like Stevens‑Johnson syndrome
• Eosinophilic granulomatosis with polyangiitis
• Anaphylaxis

When prescribing Montelukast, several safety considerations should be observed.

• Pregnancy: safety not established; use only if benefit outweighs risk.
• Breastfeeding: unknown; consider risk versus benefit.
• Pediatric use: approved for children as young as 6 months for certain indications; follow prescriber guidance.
• Drug interactions: review concomitant medications, especially phenobarbital and rifampin.
• Monitoring: observe for mood changes or allergic reactions during therapy.
• Store at ambient temperature: keep in original container, protect from moisture and direct sunlight.

Montelukast can interact with other medicines; some interactions require avoidance while others need monitoring.

Major Interactions (Avoid)

• Phenobarbital: induces metabolism, reducing efficacy.
• Rifampin: strong enzyme inducer, may lower plasma levels.
• Ketoconazole: may increase levels, risk of toxicity.

Moderate Interactions (Monitor Closely)

• Warfarin: possible alteration of anticoagulant effect.
• Theophylline: may increase plasma concentrations.
• Beta‑agonists: additive bronchodilation effect.