Drug reference

Montelukast

Leukotriene Receptor Antagonist · Antiasthmatic

Also known as Montelukast sodium

START

10 mg PO once daily in the evening

TYPICAL MAX

10 mg/day (adult)

STOP IF

Hypersensitivity · neuropsychiatric event on prior dose

WATCH

FDA black-box: mood/sleep changes · suicidal ideation

CDSCO approvedH (Prescription Drug) If it is a single-ingredient drug, it comes under Schedule H, given its potential side effects and the need for medical supervision. (Assuming it is not an OTC product.) (Revisiting the Indian context - most prescription drugs fall under Schedule H). The schema only allows a string for the schedule. So, 'H' is appropriate. (Double-checking Indian Schedule. Schedule H is for prescription-only drugs, which Montelukast is.) (Revisiting:ATC R03DC03

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 1h · absorption
PEAK: 3h · Cmax
t½: 4h · plasma t½
DURATION: 1d · once-daily dosing window

EXCRETION

CYP2C8/3A4 hepatic · biliary excretion

route + CYP

INTERACTIONS

—

none in our sources

PREGNANCY

Category B — use if clearly needed

FDA category + note

Available in India

165 branded formulations and 4,637 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Mechanism

Montelukast selectively binds to and inhibits the cysteinyl leukotriene 1 (CysLT1) receptor. This prevents the actions of leukotrienes (LTC4, LTD4, LTE4), which are potent inflammatory mediators released from mast cells and eosinophils. By blocking these receptors, Montelukast inhibits bronchoconstriction, mucus secretion, vascular permeability, and eosinophil recruitment, thus improving asthma control and allergic rhinitis symptoms.

Indications

Prophylaxis and chronic treatment of asthma in adults and pediatric patients 6 months of age and older.Prevention of exercise-induced bronchoconstriction (EIB) in patients 6 years of age and older.Relief of symptoms of seasonal allergic rhinitis in adults and pediatric patients 2 years of age and older.Relief of symptoms of perennial allergic rhinitis in adults and pediatric patients 6 months of age and older.Bronchial asthmaProphylactic therapy of mild-to-moderate asthma (as alternatives to inhaled glucocorticoids)Aspirin-induced asthmaExercise-induced asthma

Dosing

Adult: For asthma or seasonal/perennial allergic rhinitis: 10 mg orally once daily in the evening. For prevention of exercise-induced bronchoconstriction: 10 mg orally at least 2 hours before exercise; do not take an additional dose within 24 hours.
Pediatric: 6 months to 5 years: 4 mg orally once daily in the evening (chewable tablet or oral granules). 6 to 14 years: 5 mg orally once daily in the evening (chewable tablet). For prevention of exercise-induced bronchoconstriction (6-14 years): 5 mg orally at least 2 hours before exercise.
Renal adjustment: No dosage adjustment is necessary for patients with renal impairment or those on dialysis, as montelukast is not significantly excreted by the kidneys.

Pharmacokinetics

Onset

Within 1 day for asthma symptom improvement. For EIB, within 2 hours of administration.

Peak effect

2 to 4 hours after oral administration.

Duration

Approximately 24 hours

Half-life

2.7 to 5.5 hours

Bioavailability

~64%

Protein binding

>99%

Metabolism

Extensively metabolized in the liver, primarily by CYP3A4, CYP2C8, and CYP2C9 enzymes.

Excretion

Predominantly via bile in feces (approx. 86%), minimal renal excretion (<0.2%)

Contraindications

Known hypersensitivity to montelukast or any component of the formulation.
Should not be used for the reversal of bronchospasm in acute asthma attacks, including status asthmaticus.
Not to be used for terminating asthma episodes
No value in COPD

Side effects

Common

HeadacheAbdominal painUpper respiratory infectionCoughDiarrheaNauseaVomitingPyrexiaRashDizzinessRashes

Serious

Neuropsychiatric events (e.g., agitation, aggression, anxiety, depression, suicidal thoughts/behavior, hallucinations, insomnia, tremors)
Churg-Strauss syndrome (very rare, usually associated with reduction of systemic corticosteroids)
Hepatitis (rare)
Angioedema
Severe skin reactions (e.g., erythema multiforme)
Eosinophilia (infrequent)
Neuropathy (infrequent)
Churg-Strauss syndrome (few cases reported)
suicidal ideation