Montelukast

Montelukast is indicated for conditions involving leukotriene‑mediated airway inflammation and bronchoconstriction.

• Asthma: improves long‑term control of symptoms and reduces the frequency of exacerbations.
• Allergic rhinitis: alleviates nasal congestion, sneezing and itching caused by seasonal or perennial allergens.
• Exercise‑induced bronchoconstriction: prevents airway narrowing that occurs during or after physical activity, allowing better exercise tolerance.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1, preventing leukotriene D4 from binding. This inhibition reduces leukotriene‑induced bronchoconstriction, vascular permeability, and inflammatory cell recruitment in the airways, thereby improving respiratory function and decreasing allergic inflammation.

Montelukast is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Headache: mild to moderate pain often reported during treatment.
• Abdominal pain: discomfort or cramps in the stomach area.
• Cough: occasional irritation of the throat.
• Nausea: feeling of queasiness without vomiting.
• Diarrhea: loose stools occurring intermittently.
• Fatigue: reduced energy or feeling unusually tired.

Serious or Rare Side Effects

• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Neuropsychiatric events: agitation, depression, or suicidal thoughts.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.
• Hepatotoxicity: signs of liver injury such as jaundice or elevated enzymes.

Before initiating Montelukast, consider the following safety measures.

• Liver function monitoring: assess hepatic status in patients with known liver disease.
• Neuropsychiatric vigilance: watch for mood changes, depression, or suicidal ideation.
• Caution in severe hepatic impairment: dose adjustment may be required.
• Hypersensitivity: avoid use in individuals with known allergy to Montelukast or excipients.
• Not for acute asthma attacks: do not replace rescue bronchodilators.
• Store at room temperature: keep in the original pack, protect from moisture and direct sunlight.

Montelukast may interact with other medicines, altering its efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase Montelukast plasma levels.
• Phenobarbital or rifampin: can markedly reduce Montelukast exposure, decreasing therapeutic effect.

Moderate Interactions (Monitor Closely)

• Warfarin: potential for altered anticoagulant effect; monitor INR.
• Beta‑agonists (e.g., albuterol): may have additive bronchodilatory effects.
• Antidepressants (e.g., fluoxetine): monitor for neuropsychiatric symptoms.