Description: Montelukast is a selective leukotriene receptor antagonist that inhibits the effects of cysteinyl leukotrienes in the airways. Cysteinyl leukotrienes and leukotriene receptor occupation have been correlated w/ the pathophysiology of asthma, including airway oedema, smooth muscle contraction, and altered cellular activity associated w/ the inflammatory process, which contribute to the signs and symptoms of asthma.

Duration: >24 hr.


Absorption: Rapidly absorbed from the GI tract. Bioavailability: Approx 64-73%. Time to peak plasma concentration: 2-4 hr.

Distribution: Volume of distribution: 8-11 L. Plasma protein binding: >99%.

Metabolism: Extensively metabolised in the liver mainly by CYP2C8 and to a lesser extent by CYP3A4 and CYP2C9 isoenzymes.

Excretion: Excreted principally in faeces via the bile. Plasma half-life: 2.7-5.5 hr.

Montelukast is used regularly to prevent the wheezing and shortness of breath caused by asthma and decrease the number of asthma attacks. Montelukast is also used before exercise to prevent breathing problems during exercise (bronchospasm). This medication can help decrease the number of times you need to use your rescue inhaler. This medication is also used to relieve symptoms of hay fever and allergic rhinitis (such as sneezing, stuffy/runny/itchy nose).


This medication does not work immediately and should not be used to treat sudden asthma attacks or other breathing problems.


This drug works by blocking certain natural substances (leukotrienes) that may cause or worsen asthma and allergies. It helps make breathing easier by reducing swelling (inflammation) in the airways.


How to use montelukast

Read the Patient Information Leaflet if available from your pharmacist before you start taking montelukast and each time you get a refill. If you have any questions, ask your doctor or pharmacist.


Take this medication by mouth with or without food as directed by your doctor. The dosage is based on your medical condition and response to treatment. If you are using the chewable tablets, chew them thoroughly before swallowing. If your child cannot safely chew and swallow them, consult the doctor or pharmacist for advice.


Take this medication at the same time each day. If you are taking this medication for asthma or for both asthma and allergies, take your dose in the evening. If you are taking montelukast to prevent only allergies, take your dose either in the morning or the evening.


If you are taking this medication to prevent breathing problems during exercise, take your dose at least 2 hours before exercise. Do not take more than one dose in 24 hours. Do not take a dose before exercise if you are already taking this medication daily for asthma or allergies. Doing so may increase the risk of side effects.


Do not increase or decrease your dose or stop using this medication without consulting your doctor. Continue to use this medication regularly to keep your asthma under control, even during sudden asthma attacks or periods when you have no asthma symptoms. Continue to also take other medications for asthma as directed by your doctor. This medication works over time and is not meant to relieve sudden attacks of asthma. Therefore, if an asthma attack or other breathing problem occurs, use your quick-relief inhaler as prescribed. You should always have a quick-relief inhaler with you. Consult your doctor or pharmacist for more details.


Get medical help right away if your asthma symptoms worsen and your quick-relief inhaler is not helping. Tell your doctor promptly if asthma symptoms, breathing problems, allergy symptoms, number of times you use your rescue inhaler persist or worsen.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.


Tell your doctor immediately if any of these rare but serious side effects occur: mental/mood changes (such as agitation, aggression, anxiety, trouble sleeping, abnormal dreams, sleep-walking, memory/attention problems, depression, hallucinations, thoughts of harming yourself/suicide), numbness/tingling/shooting pain in the arms or legs, sinus pain/swelling, muscle weakness.


A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.


This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.



Before taking montelukast, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.


Before using this drug, tell your doctor or pharmacist your medical history, especially of: liver disease.


Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).


The chewable tablets may contain aspartame. If you have phenylketonuria (PKU) or any other condition that requires you to limit/avoid aspartame (or phenylalanine) in your diet, ask your doctor or pharmacist about using this medication safely.


During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.


It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.




Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor’s approval.



If overdose is suspected, contact a poison control center or emergency room immediately.



Do not share this medication with others.


Laboratory and/or medical tests (such as lung/breathing test) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.


Missed Dose

If you miss a dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up. Do not take more than 1 dose in 24 hours.



Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.


Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.




Available Brands:


Aerokids [ Cathay YSS ]

Aeromax [ Cathay YSS ]

Asmaflo [ Cadila Pharma ]

Averkaz [ ACME ]

Glemont-CT 4/Glemont-CT 5 [ Glenmark ]

Glemont-IR 10 [ Glenmark ]

GX Montelukast Sodium [ GXI ]

Kastair [ UAP ]

Kastair EZ Tab [ Pediatrica ]

Kastel [ Medhaus ]

Kastorion [ OEP Phils ]

Leukast [ GXI ]

Montair [ InnoGen Pharmaceuticals ]

Montekaz [ ADP Pharma ]

Montelair 5/Montelair 10 [ Hovid ]

Montemax [ Natrapharm ]

Montezyd 4/Montezyd 5/Montezyd 10 [ Zydus Healthcare Phils ]

Montiget [ Getz Pharma ]

Moscalair [ Sandoz ]

Pharex Montelukast [ Maple ]

RiteMED Montelukast [ RiteMED ]

Singulair [ Merck Sharp & Dohme ]

Teluk [ Theon Pharma ]

Terrakast [ Terramedic ]

Ventek [ Searle ]


Also marketed as:


Brecare [ Maple ]

Bronast [ Geofman ]

Lukas [ EuroHealth Care ]

Montecad-4/Montecad-5 [ Cadila Pharma ]

Montekast [ Taiwan Biotech ]

Montel 10 [ Rainbow Life Sciences ]

Montesur-4/Montesur-5/Montesur-10 [ Medchem Int’l ]

Primeair [ XL Lab ]

Tekast [ PSA ]

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