Pharmacology Of Montelukast

Indication	For the treatment of asthma
Pharmacodynamics	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.
Absorption	Rapidly absorbed following oral administration (bioavailability is 64%)
Volume of distribution	8 to 11 L
Protein binding	99% (to plasma proteins)
Metabolism	Hepatic
Route of elimination	Coupled with estimates of montelukast oral bioavailability, this indicates that montelukast and its metabolites are excreted almost exclusively via the bile.
Half life	2.7-5.5 hours
Clearance	45 mL/min [healthy adults]
Toxicity	Side effects include headache, abdominal or stomach pain, cough, dental pain, dizziness, fever, heartburn, skin rash, stuffy nose, weakness or unusual tiredness.