Cysteinyl leukotriene receptor antagonist indicated for prophylaxis and chronic treatment of asthma, acute prevention of exercise-induced bronchoconstriction, and relief of seasonal and perennial allergic rhinitis symptoms (when alternatives are inadequate or not tolerated).
Also known as: Singulair, montelucaste sódico, montelukast sodium
DailyMed approved label (Montelukast Tablet; setID 583a9499-97f0-2ebf-e063-6394a90a35af).
DailyMed approved label (Montelukast Tablet; setID 583a9499-97f0-2ebf-e063-6394a90a35af).
Montelukast + rifampicin: rifampicin may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents the montelukast interaction with rifampicin (5.1.3.2). Rifampicin is a potent CYP3A4 inducer and accelerates montelukast metabolism, potentially significantly reducing its concentrations and compromising asthma control — relevant in the asthmatic patient treated for tuberculosis. The practical guidance is to monitor asthma control (symptoms, reliever use, PEF) during the combination and consider montelukast dose adjustment or a therapeutic alternative if control is lost. The interaction is moderate, but rifampicin enzyme induction is marked, so vigilance should be active during the tuberculosis regimen.
Montelukast + rifampicin: rifampicin may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents the montelukast interaction with rifampicin (5.1.3.2). Rifampicin, a potent CYP3A4 inducer, accelerates montelukast metabolism and may significantly reduce its concentrations.
Assess asthma symptoms and respiratory function in the combination.
Loss of asthma control with the combination.
Monitor asthma control during the combination; consider dose adjustment or an alternative.
Prontuário Terapêutico do INFARMED (11th ed., 2012) — Montelukast, 5.1.3.2 ; approved Rifampicin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b389b1a3-672f-47e3-916c-4a9c044b211b
Montelukast + phenobarbital: phenobarbital may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents montelukast interactions with phenobarbital, phenytoin and rifampicin (5.1.3.2). These enzyme inducers accelerate montelukast metabolism (CYP3A4/2C9), potentially reducing its plasma concentrations and compromising asthma control. Phenobarbital is a potent enzyme inducer; the combination is possible in patients with asthma and epilepsy, but leukotriene efficacy may decrease. The practical guidance is to monitor asthma control (symptoms, nocturnal awakenings, reliever use, PEF) during the combination and consider dose adjustment or a therapeutic alternative if control is lost.
Montelukast + phenobarbital: phenobarbital may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents montelukast interactions with phenobarbital, phenytoin and rifampicin (5.1.3.2). These enzyme inducers accelerate montelukast metabolism (CYP3A4/2C9), potentially reducing its concentrations and compromising asthma control.
Assess asthma symptoms and respiratory function (PEF) in the combination.
Loss of asthma control (attack, worsening symptoms) with the combination.
Monitor asthma control during the combination; consider dose adjustment or an alternative.
Prontuário Terapêutico do INFARMED (11th ed., 2012) — Montelukast, 5.1.3.2 ; approved Phenobarbital label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ef4e97a7-cd18-47a9-a016-2eca5481a87e
Montelukast + phenytoin: phenytoin may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents the montelukast interaction with phenytoin (5.1.3.2). Phenytoin is a CYP3A4/2C9 inducer and accelerates montelukast metabolism, potentially reducing its serum concentrations and compromising the preventive effect in asthma. The combination is possible in patients with asthma and epilepsy on phenytoin. The practical guidance is to monitor asthma control (symptoms, reliever use, PEF) during the combination; if control is lost, consider montelukast dose adjustment or a therapeutic alternative. The interaction is moderate in severity and does not require prophylactic discontinuation, only clinical vigilance.
Montelukast + phenytoin: phenytoin may reduce montelukast efficacy — monitor asthma control.
The Prontuário Terapêutico documents the montelukast interaction with phenytoin (5.1.3.2). Phenytoin, a CYP3A4/2C9 inducer, accelerates montelukast metabolism and may reduce its serum concentrations.
Assess asthma symptoms and respiratory function in the combination.
Loss of asthma control with the combination.
Monitor asthma control during the combination.
Prontuário Terapêutico do INFARMED (11th ed., 2012) — Montelukast, 5.1.3.2 ; approved Phenytoin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7cbd9005-7df2-47ee-adb3-7244c1c69bc3
Montelukast should be taken without food; meals may reduce the absorption of the tablet.
Take 1 hour before or 2 hours after meals.
EMC-UK (MHRA) — approved Montelukast SmPC: https://www.medicines.org.uk/emc/product/1222/smpc
Montelukast is hepatically metabolised; use with caution in liver disease.
Monitor liver function in patients with liver disease.
EMC-UK (MHRA) — approved Montelukast SmPC: https://www.medicines.org.uk/emc/product/1222/smpc
Data on montelukast in pregnancy are limited; use only if the benefit outweighs the risk.
Can be used if asthma is not controlled with ICS alone.
Excreted into breast milk in small amounts; probably compatible.
No specific additional contraception.
EMC-UK (MHRA) — approved Montelukast SmPC: https://www.medicines.org.uk/emc/product/1222/smpc ; Prontuário Terapêutico do INFARMED (11th ed., 2012) — Annex 2, Drugs and Breastfeeding: Present in breast milk; use during breastfeeding only if the benefit is clearly greater than the risk.
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Oral selective CysLT1 receptor antagonist: blocks the effects of cysteinyl leukotrienes (LTC4, LTD4, LTE4) in the airways and nasal mucosa, reducing edema, smooth-muscle contraction and inflammatory activity associated with asthma and allergic rhinitis.
High-affinity, selective binding to the CysLT1 receptor of cysteinyl leukotrienes (in preference to other pharmacologically important receptors).
Oral bioavailability of 64% after a 10 mg tablet; plasma peaks at 3–4 hours; plasma protein binding > 99%.
Extensively metabolized (CYP3A4, CYP2C8 and CYP2C9); metabolites are excreted almost exclusively in bile.
Half-life of 2.7–5.5 hours (in healthy adults).
Medicines from the same therapeutic group (ATC classification) or the same pharmacological class.
