Montelukast
Montelukast is an oral leukotriene receptor antagonist used in adults and children for asthma maintenance, exercise-induced bronchospasm and allergic rhinitis. It is taken once daily and complements inhaled therapy in selected cases.
- Chemical formula
- C35H36ClNO3S
- CAS number
- 158966-92-8
- ATC code
- R03DC03
- Molecular weight
- 586.18 g/mol
- Drug class
- Leukotriene receptor antagonist
- Also known as
- MK-0476, Montelukast
What is it?
Montelukast is a selective antagonist of the cysteinyl leukotriene type 1 (CysLT1) receptor. It was approved in 1998 and is supplied as oral tablets, chewable tablets and oral granules, with paediatric formulations available. Montelukast is dispensed only on prescription. It is not a rescue medication and does not replace inhaled bronchodilators in acute exacerbations. Regulatory agencies have added a boxed warning in some markets regarding mental health adverse events.
Mechanism of action
Montelukast selectively blocks the CysLT1 receptor, which mediates the action of leukotrienes C4, D4 and E4 — proinflammatory mediators released by mast cells and eosinophils in the airway. By blocking this receptor, montelukast reduces bronchoconstriction, mucosal oedema and airway inflammation. The drug does not affect histamine or beta-2 adrenergic pathways and is therefore complementary to antihistamines and beta-agonists.
Pharmacokinetics
Montelukast is rapidly absorbed orally, with peak plasma concentrations reached after three to four hours. Bioavailability is approximately 64% to 73%. Plasma protein binding exceeds 99%. The drug is metabolised in the liver, mainly by CYP2C8 and CYP3A4, and excreted predominantly in faeces. The terminal half-life is approximately three to six hours, with once-daily dosing supported by sustained receptor blockade. Hepatic impairment increases exposure.
Indications
Montelukast is approved in adults and children for the maintenance treatment of asthma, including exercise-induced bronchospasm, and for the treatment of seasonal and perennial allergic rhinitis when conventional therapy is insufficient or not tolerated. According to current guidelines, montelukast is not first-line for asthma maintenance in most adults, where inhaled corticosteroids are preferred, but is useful as add-on therapy or in patients who cannot use inhalers correctly.
Safety profile
Common adverse effects include headache, gastrointestinal symptoms and upper respiratory tract infection. Neuropsychiatric adverse events have been reported, including agitation, anxiety, depression, sleep disturbances and, rarely, suicidal ideation. Several regulatory agencies have added a boxed warning. According to the prescribing information, patients and caregivers should be informed of these risks before starting treatment, and any new psychiatric symptoms should prompt review with the prescriber.
Products containing this ingredient
Frequently asked questions
Is montelukast a rescue medication? ▾
No. Montelukast is a maintenance medication, not a rescue medication. It does not produce immediate bronchodilation and is not a substitute for short-acting beta-2 agonists in acute asthma symptoms or exacerbations. According to the prescribing information, patients should always have access to an appropriate rescue inhaler and seek urgent care if asthma symptoms worsen suddenly.
What are the neuropsychiatric warnings about montelukast? ▾
Several regulatory agencies, including the FDA, have added warnings or boxed warnings about possible neuropsychiatric adverse events with montelukast, including agitation, anxiety, depression, sleep disturbances, abnormal dreams and rare reports of suicidal thoughts or behaviour. According to the prescribing information, the benefit-risk balance should be carefully discussed with the prescriber, particularly in allergic rhinitis where alternative treatments are available.
Can children take montelukast? ▾
Yes, in age- and weight-based dosing. Montelukast is approved in children from age six months in some markets, with paediatric formulations such as chewable tablets and oral granules and a graduated dose schedule defined in the prescribing information. According to clinical guidelines, paediatric prescribing should be discussed with a paediatrician, especially given the neuropsychiatric warnings and the availability of inhaled alternatives.
How is montelukast different from antihistamines in allergic rhinitis? ▾
Antihistamines block histamine at the H1 receptor, while montelukast blocks the CysLT1 receptor for leukotrienes — a complementary inflammatory pathway. In allergic rhinitis, montelukast can be effective when antihistamines and intranasal corticosteroids are insufficient or not tolerated, and the two classes can be combined under medical supervision. According to international guidelines, montelukast is generally not first-line for isolated allergic rhinitis.
What are the main contraindications for montelukast? ▾
Montelukast is contraindicated in known hypersensitivity to the molecule or its excipients. Caution is required in significant hepatic impairment, in patients with a history of psychiatric disorders or suicidal ideation given the boxed warnings, and during pregnancy and breastfeeding. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription, with attention to mental health background.
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