Montelukast

Montelukast belongs to the leukotriene modifier class of medications. To understand how it works, it helps to know what leukotrienes are and how they contribute to asthma and allergic symptoms ^{[1, 2, 13]}.

Leukotrienes are powerful inflammatory chemicals produced by immune cells (mast cells, eosinophils, basophils) as part of the allergic and inflammatory response. They are produced through the 5-lipoxygenase pathway from arachidonic acid — a different pathway from the prostaglandins targeted by NSAIDs ^{[1, 13]}.

There are several types of leukotrienes, but the cysteinyl leukotrienes (LTC4, LTD4, LTE4) are the most important in asthma and allergic disease. These leukotrienes cause three key effects in the airways: (1) bronchoconstriction — they are 100-1,000 times more potent than histamine at constricting airways; (2) increased mucus production — they stimulate goblet cells in the airway lining; and (3) inflammation and edema — they cause swelling of the airway walls and attract inflammatory cells ^{[1, 8, 13]}.

In allergic rhinitis, cysteinyl leukotrienes contribute to nasal congestion, mucus production, and inflammation of the nasal passages ^{[1, 4]}.

Montelukast works by selectively blocking the cysteinyl leukotriene receptor type 1 (CysLT1) on airway smooth muscle cells, immune cells, and other cells in the respiratory tract ^{[1, 13]}. By blocking this receptor, montelukast prevents leukotrienes from exerting their effects — airways stay more relaxed, less mucus is produced, and inflammation is reduced ^{[1, 5, 15]}.

Montelukast is taken once daily in the evening for asthma (leukotrienes are produced in higher amounts at night). It reaches peak blood levels in 3-4 hours and has a half-life of approximately 2.7-5.5 hours, but its receptor-binding effects persist for 24 hours ^[1].

When you start montelukast, do not expect the dramatic, immediate relief that a rescue inhaler (like albuterol) provides. Montelukast works gradually by reducing the underlying inflammatory component of asthma ^{[1, 5, 8]}. Some improvement may be noticed within the first day, but maximum benefit develops over the first 1-2 weeks of daily use ^{[1, 5]}.

For asthma, take montelukast once daily in the evening ^[1]. It is not a rescue medication — it does not work quickly enough to treat an acute asthma attack. Always keep your rescue inhaler available. Montelukast is a controller medication that helps prevent symptoms when taken consistently ^{[1, 8]}.

For allergic rhinitis, montelukast can be taken in the morning or evening ^{[1, 4]}. It is often used in combination with antihistamines for more complete symptom relief.

For exercise-induced bronchoconstriction, take montelukast at least 2 hours before exercise ^{[1, 15]}. Do not take an additional dose within 24 hours.

Most people tolerate montelukast well with minimal side effects. The most common side effects are headache and upper respiratory infection, which are usually mild ^[1].

However, be aware of the FDA boxed warning regarding neuropsychiatric effects ^[3]. While uncommon, montelukast has been associated with behavior changes, mood changes, depression, suicidal thoughts, and other neuropsychiatric events in some patients ^{[3, 6, 7, 14, 16]}. The FDA strengthened this warning in 2020, requiring a boxed warning and advising that montelukast should be reserved for patients who have not responded adequately to other therapies ^[3]. Monitor for these symptoms and report them to your doctor immediately.

Montelukast can be taken with or without food. Food does not significantly affect its absorption ^{[1, 2]}.

Alcohol does not have a known direct pharmacokinetic interaction with montelukast. However, alcohol can worsen the neuropsychiatric effects (depression, mood changes) that are associated with montelukast in some patients ^{[1, 3]}. Use alcohol with caution and monitor for mood changes.

The 10 mg film-coated tablet should be swallowed whole with water. The chewable tablets (4 mg and 5 mg) for children should be chewed thoroughly before swallowing. The oral granules (4 mg packet) for infants and young children can be dissolved in baby formula or breast milk, mixed with applesauce, or placed directly in the mouth ^{[1, 2]}.

There are no significant food-drug interactions ^[1]. The chewable tablets contain phenylalanine — patients with phenylketonuria (PKU) should be informed ^[1].

Asthma (adults and adolescents 15+ years) [1, 5]: - 10 mg once daily in the evening - Not for acute asthma attacks; continue rescue inhaler

Asthma (children 6-14 years) [1, 10]: - 5 mg chewable tablet once daily in the evening

Asthma (children 2-5 years) [1]: - 4 mg chewable tablet or oral granule packet once daily in the evening

Asthma (children 12-23 months, granules only) [1]: - 4 mg oral granule packet once daily in the evening

Allergic rhinitis (seasonal or perennial) [1, 4]: - Adults and adolescents 15+: 10 mg once daily - Children 6-14: 5 mg chewable tablet once daily - Children 2-5: 4 mg chewable tablet or granule packet once daily - Children 6-23 months (perennial only): 4 mg granule packet once daily

Exercise-induced bronchoconstriction (adults and adolescents 15+) [1, 15]: - 10 mg at least 2 hours before exercise - Do not take additional dose within 24 hours - If already taking daily montelukast for asthma, do not take an additional dose for exercise

Available forms [1]: - Tablets: 10 mg (film-coated) - Chewable tablets: 4 mg, 5 mg (contain phenylalanine — caution in phenylketonuria) - Oral granules: 4 mg per packet

Renal/hepatic impairment [1]: No dose adjustment needed for mild-moderate impairment; limited data in severe impairment

Generic montelukast has been available since August 2012 and is highly affordable ^{[1, 9, 11]}.

Generic montelukast 10 mg (30 tablets) typically costs $5-$15 at most pharmacies with a discount coupon ^[11]. Brand-name Singulair can cost $300+ per month without insurance.

Most insurance plans (Medicare Part D, Medicaid, commercial) cover generic montelukast with minimal copays ($5-$15). Prior authorization is rarely required ^[11].

Many pharmacy chains include generic montelukast on their $4-$10 generic drug lists ^[11].

Generic chewable tablets (4 mg, 5 mg) for children are also available at similar low prices ^[11].

Organon (manufacturer of Singulair) offers a patient assistance program for eligible uninsured patients, but the generic is so affordable that the program is rarely needed.

Pregnancy: Montelukast is not assigned a specific pregnancy category under current FDA labeling ^[1]. Animal studies did not show teratogenic effects at doses much higher than human therapeutic doses ^[1]. Available human data from published observational studies and post-marketing reports have not identified a drug-associated risk of major birth defects.

Asthma itself, if poorly controlled, poses risks to both mother and fetus (preeclampsia, preterm birth, low birth weight) ^{[1, 8]}. The National Asthma Education and Prevention Program (NAEPP) guidelines consider montelukast an acceptable alternative therapy during pregnancy for patients who have demonstrated a clear positive response before pregnancy ^[8].

Breastfeeding: Montelukast is excreted in breast milk in small amounts ^[1]. The clinical significance to the nursing infant is unclear. Given the benefits of breastfeeding and the clinical need for asthma control, montelukast may be used during breastfeeding if needed ^[1]. Monitor the infant for unusual irritability or behavioral changes.

Generic montelukast has been available since 2012 and is manufactured by numerous companies ^{[1, 9]}. All generic versions are AB-rated by the FDA as therapeutically equivalent to Singulair.

There is no clinically meaningful difference between generic montelukast and brand-name Singulair. Both contain the same active ingredient at the same strength ^{[1, 9]}.

Brand-name Singulair is rarely prescribed today. Virtually all prescriptions are filled with generic montelukast at a fraction of the original brand-name price ^{[9, 11]}.

Generic chewable tablets and oral granules (for children) are also available and therapeutically equivalent to their brand-name counterparts ^[1].