Montelukast

Montelukast is a leukotriene receptor antagonist (LTRA) that is taken as a tablet and used for the long-term treatment of asthma and allergic rhinitis. Unlike inhalers, montelukast is swallowed and acts systemically.

Leukotrienes are inflammatory messengers that play an important role in asthma. Montelukast blocks their action, thereby reducing inflammation, mucus production and bronchospasm.

Well-known brand names include Singulair®, Montelukast dura® and numerous generics. It is approved for adults and children aged 6 months and older.

Montelukast blocks the cysteinyl leukotriene receptors:

Mechanism of action: 1. Leukotrienes (LTC4, LTD4, LTE4) are released during allergic reactions 2. They cause bronchoconstriction, mucus production and inflammation 3. Montelukast competitively blocks the CysLT1 receptor 4. The action of the leukotrienes is canceled out

Effects:

• Bronchodilation (within hours)
• Anti-inflammatory action in the airways
• Reduced mucus production
• Reduction of eosinophils in the airways

Time course:

• Onset of action: within a few hours
• Full effect: after a few days of regular use
• Duration of action: 24 hours (once-daily dosing)

Montelukast is suitable for:

• Add-on therapy for asthma (to ICS)
• Exercise-induced asthma
• Allergic asthma with concurrent allergic rhinitis
• Children aged 6 months and older
• Patients who cannot use inhalers correctly

Areas of use:

• Mild persistent asthma (alternative to low-dose ICS)
• Moderate asthma as an add-on to ICS
• Prevention of exercise-induced asthma

Not suitable as:

• Sole therapy for moderate to severe asthma
• Acute treatment of asthma attacks
• A replacement for inhaled corticosteroids in most patients

Adults and adolescents aged 15 years and older:

• 10 mg film-coated tablet once daily in the evening

Children 6-14 years:

• 5 mg chewable tablet once daily in the evening

Children 2-5 years:

• 4 mg chewable tablet or granules once daily in the evening

Children 6 months to 2 years:

• 4 mg granules once daily in the evening
• Persistent asthma must be diagnosed by a pediatrician or pulmonologist

Note: Always take in the evening, as leukotriene production is highest at night.

How to take:

• Once daily in the evening, with or without food
• Swallow film-coated tablets with water
• Chew chewable tablets before swallowing them
• Place granules directly on the tongue or mix them into soft food

Important notes:

• Keep taking it even when you have no symptoms
• If neuropsychiatric symptoms occur, stop taking it and inform your doctor
• Not a substitute for a rescue inhaler
• If you forget a dose: take the next dose at the usual time

Do not use in case of:

• Hypersensitivity to montelukast or any of the ingredients

Use with caution in case of:

• Phenylketonuria (chewable tablets contain aspartame)
• Pre-existing psychiatric conditions
• Liver insufficiency (dose adjustment usually not necessary)

Pregnancy: Limited data. Use only if clearly indicated. Inhaled corticosteroids have been better studied in pregnancy.

Breastfeeding: Passes into breast milk. Weigh benefits against risks.

Common (1-10%):

• Headache
• Abdominal pain
• Diarrhea
• Nausea
• Skin rash

Uncommon:

• Dizziness
• Dry mouth
• Fatigue

Uncommon but important (neuropsychiatric effects):

• Sleep disturbances, nightmares
• Restlessness, agitation
• Depressed mood
• Behavioral changes in children
• Suicidal thoughts (very rare, but FDA warning)

Important: If mood changes, sleep disturbances or abnormal behavior occur, inform your doctor immediately!

Interactions:

• CYP3A4 and CYP2C9 inducers (phenobarbital, rifampicin) – may lower montelukast levels
• Gemfibrozil – may raise montelukast levels

No relevant interaction with:

• Inhaled corticosteroids (useful combination)
• Beta-2 agonists
• Antihistamines
• Oral contraceptives

Note: Overall, montelukast has a favorable interaction profile.