Mooncast (Montelukast)

Montelukast is used to treat conditions mediated by leukotriene pathways, primarily in respiratory disorders.

• Asthma: Improves control of chronic asthma symptoms and reduces frequency of exacerbations.
• Allergic rhinitis: Alleviates nasal congestion, sneezing and itchy eyes caused by seasonal or perennial allergies.
• Exercise‑induced bronchoconstriction: Prevents airway narrowing that occurs during or after physical activity.

• Montelukast selectively antagonizes the cysteinyl leukotriene receptor CysLT1 located on airway smooth‑muscle cells, mast cells and eosinophils. By blocking the binding of leukotriene D4, it inhibits the cascade that leads to bronchoconstriction, mucus secretion and inflammatory cell recruitment, thereby reducing airway inflammation and hyper‑responsiveness. The effect is dose‑dependent and contributes to long‑term control of airway tone without causing the rapid bronchodilation seen with rescue inhalers.

Montelukast may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Headache: mild to moderate headache reported in many patients.
• Abdominal pain: occasional stomach discomfort or cramps.
• Cough: transient cough without infection.
• Diarrhoea: loose stools occurring during early treatment.
• Nausea: feeling of queasiness or upset stomach.
• Fever: low‑grade temperature elevation.
• Upper respiratory tract infection: mild cold‑like symptoms.

Serious or Rare Side Effects

• Neuropsychiatric events: agitation, anxiety, depression or suicidal thoughts.
• Allergic reactions: rash, urticaria, angioedema or anaphylaxis.
• Hepatic dysfunction: elevated liver enzymes or hepatitis.
• Blood disorders: eosinophilia or neutropenia.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.

When prescribing Montelukast, clinicians should consider several precautionary measures to ensure safe use.

• Assess asthma control: confirm that the patient’s asthma is not uncontrolled before initiating therapy.
• Monitor for neuropsychiatric symptoms: watch for mood changes, depression or suicidal ideation during treatment.
• Evaluate liver function: consider baseline hepatic tests in patients with known liver disease.
• Use with caution in the elderly: dose adjustments may be needed due to potential comorbidities.
• Avoid in patients with known hypersensitivity to Montelukast or any tablet excipients.
• Store at ambient temperature: keep below 25 °C, retain in original packaging, protect from moisture and direct sunlight.

Montelukast can interact with other medicines, affecting its plasma levels or therapeutic effect.

Major Interactions (Avoid)

• Rifampin: strong enzyme inducer that may markedly reduce Montelukast concentrations.
• Phenobarbital: induces CYP enzymes leading to decreased drug exposure.
• Carbamazepine: may lower Montelukast plasma levels through hepatic induction.

Moderate Interactions (Monitor Closely)

• Ketoconazole: CYP3A4 inhibitor that can increase Montelukast exposure.
• Erythromycin: may raise Montelukast levels modestly.
• Fluconazole: potential to elevate Montelukast concentrations.
• Warfarin: monitor INR as Montelukast may slightly affect anticoagulation.