indication

For the treatment of asthma

pharmacology

Montelukast, like zafirlukast, is a leukotriene receptor antagonist used as an alternative to anti-inflammatory medications in the management and chronic treatment of asthma and exercise-induced bronchospasm (EIB). Unlike zafirlukast, montelukast does not inhibit CYP2C9 or CYP3A4 and is, therefore, not expected to affect the hepatic clearance of drugs metabolized by these enzymes.

mechanism of action

Montelukast selectively antagonizes leukotriene D₄ (LTD₄) at the cysteinyl leukotriene receptor, CysLT₁, in the human airway. Montelukast inhibits the actions of LTD₄ at the CysLT₁ receptor, preventing airway edema, smooth muscle contraction, and enhanced secretion of thick, viscous mucus.

toxicity

Side effects include headache, abdominal or stomach pain, cough, dental pain, dizziness, fever, heartburn, skin rash, stuffy nose, weakness or unusual tiredness.

biotransformation

Hepatic

absorption

Rapidly absorbed following oral administration (bioavailability is 64%)

half life

2.7-5.5 hours

route of elimination

Coupled with estimates of montelukast oral bioavailability, this indicates that montelukast and its metabolites are excreted almost exclusively via the bile.