1. Clinical Overview
Montelukast is a potent, selective, and orally active leukotriene receptor antagonist (LTRA) that blocks the action of cysteinyl leukotrienes (CysLTs) at the CysLT1 receptor. It is a cornerstone in the prophylactic and chronic treatment of asthma and allergic rhinitis, offering a non-steroidal anti-inflammatory option. It is particularly valued for its once-daily dosing, oral bioavailability, and favorable safety profile in the Indian context.
| Onset | Duration | Bioavailability |
|---|---|---|
| Clinical improvement in asthma symptoms may be seen within 1 day, but full therapeutic effect for asthma prophylaxis may take up to 2-4 weeks. For allergic rhinitis, relief can be observed on the first day of dosing. | Approximately 24 hours, supporting once-daily administration. | Approximately 64% for the 10mg film-coated tablet. |
2. Mechanism of Action
Montelukast selectively and competitively inhibits the cysteinyl leukotriene type 1 (CysLT1) receptor. Cysteinyl leukotrienes (LTC4, LTD4, LTE4) are potent inflammatory eicosanoids released from mast cells, eosinophils, and other cells in the airway. By blocking their receptor, montelukast inhibits the bronchoconstrictor and pro-inflammatory effects of these mediators.
3. Indications & Uses
- Prophylaxis and chronic treatment of asthma in adults and pediatric patients 15 months and older.
- Relief of symptoms of allergic rhinitis (seasonal and perennial) in adults and pediatric patients 2 years and older.
4. Dosage & Administration
Adult Dosage: 10 mg once daily in the evening for asthma and allergic rhinitis. For EIB, a single 10 mg dose at least 2 hours before exercise; no additional dose within 24 hours.
Administration: Can be taken with or without food. The tablet should be swallowed whole with water. For granules: Can be administered directly in the mouth, dissolved in 5 mL of cold or room temperature baby formula/breast milk, or mixed with a spoonful of soft food (applesauce, carrots, rice, ice cream). Do not dissolve in liquid other than specified. Once opened, the entire sachet must be used immediately.
5. Side Effects
Common side effects may include:
- Headache
- Abdominal pain
- Dyspepsia
- Upper respiratory tract infection
- Fever
- Cough
- Rhinorrhea
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Phenobarbital, Rifampicin | Inducers of CYP450 enzymes may decrease montelukast plasma concentrations. Clinical significance is unclear but monitor for reduced efficacy. | Moderate |
| Gemfibrozil | Inhibitor of CYP2C8/CYP2C9; may increase montelukast plasma concentration. Monitor for increased side effects. | Moderate |
| Prednisone, other systemic corticosteroids | Montelukast allows for a reduction in steroid dose in some patients. Taper steroids cautiously under medical supervision. | Moderate |
| Aspirin, NSAIDs | No direct pharmacokinetic interaction. Montelukast is used to treat reactions in aspirin-exacerbated respiratory disease. | None |
7. Patient Counselling
- DO take the medicine once daily in the evening, as prescribed, even if you feel well.
- DO continue taking your other asthma/allergy medications unless your doctor advises otherwise.
- DO use your quick-relief inhaler (salbutamol) for acute asthma symptoms; montelukast will not help during an attack.
- DONT stop taking montelukast abruptly without consulting your doctor.
- DONT use it to treat an acute asthma attack.
8. Toxicology & Storage
Overdose: Experience in adults with doses up to 1000 mg/day is limited. Symptoms may include headache, vomiting, psychomotor hyperactivity, thirst, somnolence, mydriasis, hyperkinesia, and abdominal pain.
Storage: Store below 30°C. Protect from moisture and light. Keep the granules/tablets in the original package until use. Keep out of reach of children.