Montelukast
Singulair
Overview
Leukotriene receptor antagonist used for asthma maintenance and allergic rhinitis.
Indications
- Chronic asthma (prophylaxis)
- Exercise-induced bronchospasm prevention
- Allergic rhinitis (seasonal and perennial)
Contraindications
- Hypersensitivity to montelukast
Classification
Mechanism of Action
Selectively blocks cysteinyl leukotriene receptor CysLT1, preventing leukotriene-mediated bronchoconstriction, mucus secretion, and airway inflammation.
Pharmacodynamics
Reduces airway inflammation and bronchoconstriction. Does not relieve acute bronchospasm.
Pharmacokinetics
- Absorption
- Rapidly absorbed. Peak levels 3-4 hours (tablet), 2-2.5 hours (chewable).
- Distribution
- Volume of distribution 8-11 L. Crosses blood-brain barrier minimally.
- Metabolism
- Extensive hepatic via CYP3A4, CYP2C8, CYP2C9.
- Excretion
- Fecal (86%), renal minimal.
- Half-life
- 2.7-5.5 hours
- Bioavailability
- 64% (tablet)
- Protein Binding
- >99%
Dosage
Typical dosage: 10mg once daily in evening (adults)
Available Forms
- Tablet
- Chewable tablet
- Granules
Side Effects
Common
- Headache
- Upper respiratory infection
- Abdominal pain
Serious
- Neuropsychiatric events (agitation, depression, suicidal thinking)
- Eosinophilic conditions
- Hepatic events
Rare
- Anaphylaxis
- Angioedema
- Churg-Strauss syndrome
Drug Interactions
CYP3A4 inducers may decrease montelukast levels. Clinical significance uncertain.
Warnings
Serious neuropsychiatric events have been reported. Monitor for changes in behavior or mood, including agitation, depression, sleep disturbances, and suicidal thinking.
Pregnancy
Category B
Toxicity
LD50 >5000 mg/kg (oral, rat)
Overdose
Symptoms: abdominal pain, somnolence, headache. No specific antidote. Supportive care.
References
Looking for patient-friendly information? Visit RemedyDoor for easy-to-read guides about this medication.