Montelukast

Singulair is labeled for prevention and chronic treatment of asthma from age 12 months, prevention of exercise-induced bronchoconstriction from age 6 years, seasonal allergic rhinitis from age 2 years, and perennial allergic rhinitis from age 6 months.

For allergic rhinitis, use only when alternatives are ineffective or not tolerated. Discuss benefits and neuropsychiatric risks before prescribing for asthma or exercise-related symptoms. Montelukast is not rescue treatment for acute bronchospasm or status asthmaticus.

For asthma, give in the evening without regard to food. For rhinitis alone, individualize the time; food does not dictate administration. A patient with both asthma and rhinitis takes one dose in the evening.

For patients aged 6–14 years, give 5 mg; for those aged 15 years or older, give 10 mg, at least 2 hours before exercise. Do not repeat within 24 hours. Patients taking montelukast daily must not take an additional exercise dose. Keep prescribed short-acting rescue medicine available; daily asthma dosing has not been established to prevent an acute exercise episode.

Open a packet only when ready to administer. Give directly into the mouth, or mix with one teaspoon (5 mL) of cold or room-temperature baby formula or breast milk. The label also permits a spoonful of cold or room-temperature applesauce, carrots, rice, or ice cream. Do not dissolve in other liquids; liquids may be taken afterward.

Give the entire packet within 15 minutes of opening. Discard unused mixture and do not save it for later. Granules may be given without regard to meals.

No renal adjustment is recommended. Mild-to-moderate hepatic impairment does not require adjustment; severe hepatic impairment and hepatitis have not been evaluated. Skip a missed dose and take the next at its usual time; do not double.

Hypersensitivity to any component of the selected product.

The selected product has a boxed warning for serious neuropsychiatric events, including suicidal thoughts and behavior. Discuss the risk, monitor symptoms, and stop for new symptoms. The warning restricts allergic rhinitis use to patients with inadequate response or intolerance to alternatives.

Common events in controlled trials included upper respiratory infection, fever, headache, pharyngitis, cough, abdominal pain, diarrhea, and ear or sinus infections; patterns differ by age and indication. Postmarketing reports include serious neuropsychiatric events, hypersensitivity including anaphylaxis, severe skin reactions, and liver injury. Voluntary reports do not establish frequency.

Lack of a pharmacokinetic dose adjustment with NSAIDs does not make an aspirin-triggering medicine safe in aspirin-sensitive asthma. Continue the clinician-directed avoidance plan.

Observational pregnancy studies have not established an increased risk of major birth defects, but study limitations remain. Poorly controlled asthma itself increases maternal and infant risks; review the treatment plan with the clinician.

Montelukast is present in human milk. Available infant data do not suggest a significant adverse-reaction risk; effects on milk production are unknown. Consider breastfeeding benefits, maternal need, and infant exposure.

The minimum age is indication-specific: asthma 12 months, exercise prevention 6 years, seasonal rhinitis 2 years, and perennial rhinitis 6 months. Use the age-appropriate formulation. Older adults do not require a dose adjustment solely for age.

Renal elimination is negligible, and no renal adjustment is recommended. No adjustment is required in mild-to-moderate hepatic impairment. Severe impairment or hepatitis lacks pharmacokinetic evaluation; obtain individualized advice rather than extrapolating.

Montelukast selectively antagonizes the CysLT1 receptor, inhibiting leukotriene-mediated airway effects such as smooth-muscle contraction, edema, and inflammatory activity. It has no receptor agonist activity.

Adult 10 mg tablet

Peak concentration about 3–4 hours; oral bioavailability about 64%

Protein binding

More than 99%

Metabolism

Extensive; CYP2C8 is important, with CYP3A4 and CYP2C9 involvement

Elimination

Predominantly bile/feces; half-life about 2.7–5.5 hours in healthy young adults

Chewables and granules have different absorption characteristics from the adult tablet. The 4 mg granules and 4 mg chewable were bioequivalent in fasted adults, supporting the labeled pediatric choices; this is not permission to improvise an adult regimen with multiple chewables.

Assess asthma or rhinitis response, rescue-inhaler use, adherence, and new mood, behavior, or sleep changes. Continue watching neuropsychiatric symptoms after stopping. During steroid reduction, investigate signs of systemic eosinophilic disease.

Explain the boxed warning before starting, including symptoms that require immediate discontinuation and clinician contact. Keep rescue medicine available and seek urgent care for severe breathing difficulty. Do not independently stop corticosteroids or add an extra exercise dose. Teach packet preparation and check phenylalanine exposure when relevant.

Seek medical or poison-center advice for excess dosing. Reported overdose symptoms include abdominal pain, sleepiness, thirst, headache, vomiting, and hyperactivity. Management is supportive; removal by peritoneal dialysis or hemodialysis is unknown.

Selected product

Singulair 10 mg film-coated tablets · Organon LLC

Appearance

Beige, rounded square tablet

Imprint

MSD 117 on one side; SINGULAIR on the other

Example NDC

78206-172-01 · bottle of 30

The selected label includes 10 mg film-coated tablets, 4 mg and 5 mg chewable tablets, and 4 mg oral granule packets. Chewables contain phenylalanine. Generic products may have different appearance, ingredients, and packaging.

Store at 20–25°C, with permitted excursions of 15–30°C. Protect from moisture and light, and keep in the original package. Open granule packets only when ready; administer within 15 minutes and discard unused mixture.