Basics
Montelukast sodium, the active ingredient in SINGULAIR, is a selective and orally active leukotriene receptor antagonist that inhibits the cysteinyl leukotriene CysLT1 receptor.

Montelukast sodium is a hygroscopic, optically active, white to off-white powder. Montelukast sodium is freely soluble in ethyl alcohol, methanol, and water and practically insoluble in acetonitrile.

Each 10-mg film-coated SINGULAIR tablet contains 10.4 mg montelukast sodium, which is equal to 10 mg of montelukast, and the following inactive ingredients: microcrystalline cellulose, lactose monohydrate (89.3 mg), croscarmellose sodium, hydroxypropyl cellulose, and magnesium stearate. The film coating consists of: hydroxypropyl methylcellulose, hydroxypropyl cellulose, titanium dioxide, red ferric oxide, yellow ferric oxide, and carnauba wax.
Each 4-mg and 5-mg chewable SINGULAIR tablet contains 4.2 and 5.2 mg montelukast sodium, respectively, which equates 4 and 5 mg of montelukast, respectively. Both chewable tablets contain the following inactive ingredients: mannitol, microcrystalline cellulose, hydroxypropyl cellulose, red ferric oxide, croscarmellose sodium, cherry flavor, aspartame, and magnesium stearate.

Each packet of SINGULAIR 4-mg oral granules contains 4.2 mg montelukast sodium, which is equal to 4 mg of montelukast. The oral granule formulation consists of the following inactive ingredients: mannitol, hydroxypropyl cellulose, and magnesium stearate.

Side Effects

The most common adverse reactions in controlled clinical trials were:
Upper respiratory infection, Fever, Headache, Pharyngitis, Cough, Abdominal pain, Diarrhea, Influenza, Rhinorrhea, Sinusitis and Otitis.
Other effects are:
Asthenia/fatigue, Trauma, Dyspepsia, Gastroenteritis, Dizziness, Influenza, and Skin Rash

DOSAGE

Asthma
SINGULAIR should be taken once daily in the evening. The following doses are recommended:
For adults and adolescents 15 years and above: one 10-mg tablet.
For children 6 to 14 years old: one 5-mg chewable tablet.
For kids 2 to 5 years of age: one 4-mg chewable tablet or one packet of 4-mg oral granules.
For children 12 to 23 months old: one packet of 4-mg oral granules.
Safety and effectiveness in kids less than 12 months of age with asthma have not been established.
Exercise-Induced Bronchoconstriction (EIB) in Patients 15 Years and above
For prevention of EIB, a single 10 mg dose should be taken at least 2 hours before exercise.
An additional dose should not be taken within 24 hours of a previous dose.
All patients should have at hand a short-acting ?-agonist for rescue.
Safety and effectiveness in patients younger than 15 years of age have not been established.
Allergic Rhinitis

SINGULAIR should be taken once every day.
The following doses for the treatment of symptoms of seasonal allergic rhinitis are recommended:
For adults and youngsters from 15 years and above: one 10-mg tablet.
For Children 6 to 14 years of age: one 5-mg chewable tablet.
For children 2 to 5 years of age: one 4-mg chewable tablet or one packet of 4-mg oral granules.

Asthma and Allergic Rhinitis

Patients suffering from both asthma and allergic rhinitis should take only one dose daily in the evening.

OVERDOSAGE

No specific information is available on the treatment of overdose.
In chronic asthma studies, montelukast has been administered at doses up to 200 mg/day to adult patients for 22 weeks and, in short-term studies, up to 900 mg/day to patients for approximately a week without clinically important adverse experiences.
In the event of overdose, it is reasonable to call emergency services immediately.