Montast (Montelukast)

Montelukast acts on the leukotriene pathway to control respiratory and allergic conditions.

• Asthma: reduces frequency of symptoms, improves lung function and decreases need for rescue medication.
• 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 on airway smooth muscle and inflammatory cells. By antagonizing this receptor, it inhibits leukotriene‑mediated bronchoconstriction, vascular permeability, mucus secretion and eosinophilic inflammation, thereby improving airway patency and reducing allergic inflammation.

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

Common Side Effects

• Headache: mild to moderate intensity.
• Upper respiratory tract infection: transient symptoms.
• Abdominal pain: occasional discomfort.
• Cough: non‑productive.
• Diarrhea: loose stools.
• Rash: mild skin irritation.

Serious or Rare Side Effects

• Mood changes: including depression or suicidal thoughts.
• Allergic reactions: urticaria, angioedema, or anaphylaxis.
• Hepatotoxicity: elevated liver enzymes.
• Stevens‑Johnson syndrome: severe skin eruption.
• Churg‑Strauss syndrome: vasculitic disorder.
• Severe bronchospasm: paradoxical worsening of breathing.

Before initiating therapy, consider the following precautions.

• Pregnancy: safety data are limited; discuss risks with a healthcare professional.
• Breastfeeding: montelukast is excreted in milk; evaluate benefit‑risk ratio.
• Hepatic impairment: use with caution and monitor liver function.
• Concomitant asthma therapy: do not replace inhaled corticosteroids or bronchodilators.
• Age restrictions: pediatric dosing differs from adult dosing; follow prescriber guidance.
• Storage: Store below 25°C: keep in the original container, protect from moisture and direct sunlight.

Montelukast may interact with other medicines; monitor accordingly.

Major Interactions (Avoid)

• Phenobarbital: may reduce montelukast plasma concentrations.
• Rifampin: induces metabolism, potentially lowering effectiveness.

Moderate Interactions (Monitor Closely)

• Antidepressants (e.g., fluoxetine): may increase risk of neuropsychiatric events.
• Warfarin: occasional reports of altered INR; monitor coagulation.
• CYP2C9 inhibitors (e.g., fluconazole): may modestly raise montelukast levels.
• Herbal supplements containing St. John’s wort: could decrease drug exposure.