Montelukast Zentiva (Montelukast)

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

• Asthma: improves long‑term control and reduces exacerbations in patients with persistent asthma.
• Allergic rhinitis: alleviates nasal congestion, sneezing and itching associated with seasonal or perennial allergic rhinitis.
• Exercise‑induced bronchoconstriction: prevents airway narrowing that occurs during or after physical activity.

• Montelukast selectively blocks cysteinyl leukotriene (CysLT1) receptors, preventing leukotrienes D4, E4 and related mediators from binding. This inhibition reduces bronchoconstriction, mucus secretion, vascular permeability and airway edema, thereby improving airflow and decreasing inflammatory responses in the respiratory tract.

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

Common Side Effects

• Headache: mild to moderate pain often reported.
• Abdominal pain: discomfort or cramping in the stomach area.
• Cough: occasional dry or productive cough.
• Nausea: feeling of queasiness or urge to vomit.
• Diarrhea: loose, watery stools.
• Fatigue: unusual tiredness or lack of energy.

Serious or Rare Side Effects

• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Mood changes: depression, anxiety, or suicidal thoughts.
• Stevens‑Johnson syndrome: severe skin blistering and mucosal involvement.
• Liver injury: elevated enzymes or hepatitis.
• Angioedema: rapid swelling of face, lips, or throat.
• Blood dyscrasias: rare cases of neutropenia or eosinophilia.

Before initiating therapy, consider the following safety measures.

• Assess liver function: monitor patients with hepatic impairment.
• Review psychiatric history: observe for mood changes or suicidal ideation.
• Evaluate for hypersensitivity: avoid use in individuals with known allergy to montelukast.
• Consider age‑related dosing: pediatric patients require careful dose selection by the prescriber.
• Avoid use during acute asthma attacks: not a rescue medication.
• Store at ambient temperature: keep below 25°C in the original container, protect from moisture and direct sunlight.

Montelukast may interact with other medicines, requiring attention to potential changes in efficacy or safety.

Major Interactions (Avoid)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): may increase montelukast plasma concentrations.
• Phenobarbital, phenytoin, carbamazepine: can markedly reduce montelukast levels, compromising effectiveness.

Moderate Interactions (Monitor Closely)

• Ritonavir: may elevate montelukast exposure, warranting clinical observation.
• Rifampin: may lower montelukast concentrations, consider alternative therapy.
• Warfarin: occasional reports of altered INR; monitor coagulation parameters.
• Beta‑agonists: additive bronchodilation effect, monitor for excessive airway relaxation.
• Antidepressants (SSRIs): rare reports of enhanced neuropsychiatric effects; observe mood changes.