Montelukast is an oral leukotriene receptor antagonist that is used for the treatment of asthma and seasonal allergic rhinitis (hay fever). Leukotrienes are a group of naturally occurring chemicals in the body that promote inflammation in asthma and seasonal allergic rhinitis and in other diseases in which inflammation is important (such as allergy). They are formed by cells, released, and then bound to other cells that cause inflammation. It is the binding to other cells that stimulates the cells to cause inflammation. Montelukast works in a manner similar to zafirlukast (Accolate), blocking the binding of some leukotrienes to the cells that cause inflammation. Unlike zafirlukast, montelukast does not inhibit CYP2C9 or CYP3A4, two enzymes in the liver that are important in breaking down and eliminating many drugs. Therefore, unlike zafirlukast, montelukast is not expected to affect the elimination of other drugs. The safety and effectiveness of montelukast has been demonstrated in children as young as 6 months of age. It was approved by the FDA in 1998.

Singulair

GENERIC AVAILABLE: Yes

Yes

The most common side effects with montelukast are:

• headache,
• dizziness,
• abdominal pain,
• sore throat, and
• rhinitis (inflammation of the inner lining of the nose).

Other important side effects include:

• wheezing,
• cough,
• rash,
• restlessness,
• tremor, and
• nausea.

Elevated liver enzymes, suicidal behavior, fluid retention, depression, and hallucinations have also been reported.

The recommended dose of montelukast in adults is 10 mg daily for treating asthma and allergic rhinitis and 10 mg two hours before exercising for prevention of exercise induced bronchospasm. Montelukast should be taken in the evening with or without food when used for asthma or allergic rhinitis. The 4 and 5 mg tablets are used in children.

Phenobarbital, rifampin, and carbamazepine (Tegretol, Tegretol XR, Equertro, Carbatrol) may decrease blood concentrations of montelukast. This may reduce the effect of montelukast.

Montelukast crosses the placenta into the fetus following oral administration to animals, but there have been no adequate studies in pregnant women to determine the effects on the fetus. Physicians may prescribe zafirlukast during pregnancy if it is felt that its benefits outweigh the potential but unknown risks to the fetus.

Studies in animals have shown that montelukast is excreted in milk; however, it is not known if montelukast is secreted into breast milk in humans.

What preparations of montelukast are available?

Tablets: 10 mg. Chewable tablets: 4 and 5 mg.

How should I keep montelukast stored?

Tablets should be stored at room temperature, 15 C - 30 C (59 F - 86 F).