Montelukast Viatris (Montelukast)

Montelukast is a leukotriene receptor antagonist used to manage respiratory and allergic conditions.

• Asthma: reduces the frequency of asthma attacks and improves overall disease control.
• Allergic rhinitis: alleviates nasal congestion, sneezing, itching and watery discharge associated with seasonal allergies.
• Exercise‑induced bronchoconstriction: prevents airway narrowing during physical activity, helping maintain exercise tolerance.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1, preventing leukotriene D4 from binding. This inhibition reduces leukotriene‑mediated 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.
• Abdominal pain: discomfort or cramps in the stomach area.
• Cough: occasional dry or productive cough.
• Nausea: feeling of queasiness or urge to vomit.
• Dizziness: transient light‑headedness.
• Fatigue: unusual tiredness or lack of energy.

Serious or Rare Side Effects

• Allergic reactions: rash, itching, swelling, or angioedema.
• Neuropsychiatric events: mood changes, depression, or suicidal thoughts.
• Hepatic enzyme elevation: abnormal liver function tests.
• Neutropenia: reduced white blood cell count.
• Anaphylaxis: rare, severe systemic allergic response.

Before prescribing Montelukast, clinicians should consider several safety aspects.

• Assess asthma control: ensure baseline control before adding therapy.
• Monitor neuropsychiatric symptoms: watch for mood changes or depression.
• Use caution in hepatic impairment: adjust therapy if liver disease is present.
• Review concomitant medications: check for potential drug interactions.
• Educate patients on adherence: emphasize consistent daily use.
• Store at room temperature: keep in the original container, protect from moisture.

Montelukast may interact with other medicines, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Strong CYP3A4 inducers (e.g., rifampin, carbamazepine): may markedly lower montelukast exposure.
• Concurrent use with other leukotriene receptor antagonists (e.g., zafirlukast): additive pharmacologic effect increases risk of adverse events.

Moderate Interactions (Monitor Closely)

• Phenobarbital: moderate enzyme inducer that can reduce drug levels.
• Antidepressants (SSRIs, SNRIs): may heighten neuropsychiatric risk.
• Warfarin: possible alteration of INR, requiring monitoring.
• Theophylline: potential increase in plasma concentrations.