Montelukast Unimark (Montelukast Sodium)

Montelukast acts on the leukotriene pathway to control chronic airway diseases.

• Asthma: improves long‑term control 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 from binding. This inhibition reduces leukotriene‑mediated bronchoconstriction, vascular permeability, and inflammatory cell recruitment, thereby improving airway patency and decreasing allergic inflammation.

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

Common Side Effects

• Headache: mild to moderate intensity.
• Abdominal pain: occasional discomfort.
• Cough: transient respiratory irritation.
• Nausea: occasional upset stomach.
• Diarrhea: loose stools.
• Upper respiratory infection: mild cold‑like symptoms.

Serious or Rare Side Effects

• Allergic reactions: rash, angioedema, or anaphylaxis.
• Neuropsychiatric events: mood changes, depression, or suicidal thoughts.
• Hepatic enzyme elevation: abnormal liver function tests.
• Stevens‑Johnson syndrome: severe skin eruption.
• Eosinophilic pneumonia: rare lung inflammation.
• Severe hypersensitivity: bronchospasm or anaphylactoid response.

Before initiating therapy, clinicians should consider several safety aspects.

• Assess asthma control: ensure baseline therapy is optimized.
• Monitor neuropsychiatric symptoms: watch for mood changes or suicidal ideation.
• Avoid in patients with known hypersensitivity to montelukast or excipients.
• Use caution in hepatic impairment: dose adjustment may be required.
• Review concomitant medications for potential interactions.
• Store at ambient temperature below 25°C: keep in original packaging, protect from moisture and direct sunlight.

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

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase montelukast plasma levels.
• Potent CYP2C9 inhibitors (e.g., fluconazole): could raise exposure.
• Phenobarbital or rifampicin: enzyme inducers that markedly reduce effectiveness.

Moderate Interactions (Monitor Closely)

• Warfarin: possible alteration of anticoagulant effect.
• Ritonavir: may modestly increase montelukast concentrations.
• Other leukotriene modifiers: additive effects on leukotriene pathways.
• Antidepressants (e.g., fluoxetine): monitor for neuropsychiatric signs.
• Beta‑agonists: no direct interaction but combined therapy may affect symptom control.