Montulair 4/Montulair 10 Mechanism of Action

Pharmacology: PHARMACODYNAMICS: Montelukast sodium is a selective leukotriene receptor antagonist that inhibits the cysteinyl leukotriene receptor. Cysteinyl leukotrienes and leukotriene receptor occupation have been correlated with the pathophysiology of asthma, including airway edema, smooth muscle contraction, and altered cellular activity associated with the inflammatory process, which contribute to the signs and symptoms of asthma. Cysteinyl leukotrienes are also released from the nasal mucosa following allergen exposure leading to symptoms associated with allergic rhinitis.
PHARMACOKINETICS: Absorption: Tmax, oral, film-coated tablet: 3 hours to 4 hours.
Tmax, oral, granules: 2.3 hours.
Bioavailability: (Film-coated tablet) 64%.
Effect of food: (Granule) Decreases Cmax by 35% and prolonged Tmax to 6.4 hours.
Distribution: Vd: 8 to 11 L.
Protein binding: More than 99%.
Metabolism: Hepatic: Extensively, primarily via CYP 2C8.
Substrate of CYP 2C8, CYP 2C9, and CYP 3A4.
Excretion: Bile: Almost exclusively.
Fecal: 86%.
Renal: Less than 0.2%.
Dialyzable: Unknown (hemodialysis), unknown (peritoneal dialysis).
Plasma clearance: 45 mL/min.
Elimination Half Life: 2.7 to 5.5 hours.
Mild to moderate hepatic impairment: 7.4 hours.