Mondeo (Montelukast)

Montelukast is a leukotriene receptor antagonist used to treat conditions driven by leukotriene‑mediated inflammation.

• Asthma: improves symptom control and reduces the frequency of exacerbations.
• Allergic rhinitis: relieves nasal congestion, sneezing and itching caused by seasonal allergens.
• Exercise‑induced bronchoconstriction: prevents airway narrowing during physical activity.

• Montelukast selectively blocks the cysteinyl leukotriene receptor CysLT1 on airway smooth‑muscle cells, mast cells and eosinophils. By antagonising this receptor, it prevents leukotriene‑mediated bronchoconstriction, mucus secretion and inflammatory cell recruitment, thereby reducing airway narrowing and allergic inflammation.

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

Common Side Effects

• Headache: mild to moderate pain often transient.
• Abdominal pain: discomfort or cramps in the stomach area.
• Nausea: feeling of queasiness, sometimes with vomiting.
• Dizziness: light‑headed sensation, especially on standing.
• Fatigue: unusual tiredness or lack of energy.
• Cough: persistent dry cough in some patients.

Serious or Rare Side Effects

• Allergic reactions: rash, angioedema or anaphylaxis requiring immediate care.
• Mood changes: depression, anxiety or suicidal thoughts.
• Hepatic injury: signs of liver dysfunction such as jaundice.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.
• Blood dyscrasias: neutropenia or eosinophilia.
• Severe rash: widespread erythema or exfoliative dermatitis.

Before initiating therapy, clinicians should consider several safety aspects.

• Assess liver function: monitor hepatic enzymes in patients with existing liver disease.
• Avoid in hypersensitivity: discontinue if the patient shows known allergy to montelukast or excipients.
• Monitor psychiatric status: observe for mood alterations, especially in adolescents.
• Adjust for renal impairment: use caution and consider dose modification in severe renal failure.
• Pregnancy and lactation: discuss risk‑benefit with the prescriber as data are limited.
• Store at room temperature: keep in the original pack, protect from moisture and light.

Montelukast may interact with other medicines, requiring attention to the interaction level.

Major Interactions (Avoid)

• Ritonavir: may increase montelukast plasma concentrations.
• Phenobarbital: may reduce montelukast effectiveness by inducing metabolism.
• Carbamazepine: may lower drug exposure, decreasing therapeutic benefit.

Moderate Interactions (Monitor Closely)

• Warfarin: may modestly increase INR, requiring coagulation monitoring.
• Theophylline: additive bronchodilator effect may enhance respiratory response.
• Fluconazole: may raise montelukast levels slightly, warranting observation.