Montelukast

A leukotriene receptor antagonist used in asthma and allergic conditions.

What is Montelukast?

Montelukast is a leukotriene receptor antagonist (LTRA) used to prevent asthma symptoms and relieve allergic rhinitis.

It is not a rescue medicine but works best when taken regularly.

History & Background

Montelukast was developed to target leukotrienes, chemical mediators involved in inflammation, bronchoconstriction, and mucus production.

Chemical Structure & Properties

• IUPAC name: (R)-2-(1-((1-(3-(2-(7-chloroquinolin-2-yl)ethenyl)phenyl)-3-(2-hydroxypropan-2-yl)thio)methyl)cyclopropyl)acetic acid
• Molecular formula: C₃₅H₃₆ClNO₃S
• Molar mass: 586.18 g/mol
• Functional groups: Carboxylic acid, thioether, aromatic rings

Mechanism of Action

Montelukast blocks CysLT₁ leukotriene receptors, resulting in:

• Reduced bronchoconstriction
• Decreased airway inflammation
• Less mucus secretion

Pharmacokinetics

• Absorption: Well absorbed orally
• Peak plasma time: 3–4 hours
• Metabolism: Liver (CYP3A4, CYP2C9)
• Half-life: 2.7–5.5 hours
• Excretion: Bile

Medical Uses

• Bronchial asthma (maintenance therapy)
• Allergic rhinitis
• Exercise-induced bronchoconstriction
• Aspirin-sensitive asthma

Dosage Guidelines

Adults: 10 mg once daily (evening)

Children: Dose varies by age

⚠️ Not for acute asthma attacks.

Side Effects

• Headache
• Abdominal pain
• Fatigue
• Upper respiratory infection

Warnings & Precautions

• Neuropsychiatric effects (rare)
• Monitor mood and behavior changes
• Do not abruptly stop asthma steroids

Drug Interactions

• Rifampicin (reduces effectiveness)
• Phenobarbital

Frequently Asked Questions

Is montelukast a steroid? – No.

Does it give instant relief? – No.

Best time to take? – Evening.

Safe long-term? – Yes, under supervision.

⚠️ Educational content only. Not a substitute for professional medical advice.