Nasonex Mechanism of Action

Mometasone furoate is a topical glucocorticosteroid with local anti-inflammatory properties at doses that are not systemically active.
Pharmacology: Pharmacodynamics: In studies utilizing nasal antigen challenge, mometasone furoate in NASONEX Aqueous Nasal Spray has shown anti-inflammatory activity in both the early- and late-phase allergic responses. This has been demonstrated by decreases (vs. placebo) in histamine and eosinophil activity and reductions (vs. baseline) in eosinophils, neutrophils, and epithelial cell adhesion proteins. Because of the low systemic availability of mometasone furoate after intranasal administration, any pharmacodynamic correlations have to be based upon sensitive indices of possible systemic exposure rather than measured mometasone furoate levels. Systemic activity of exogenous corticosteroids is commonly expressed by evaluating the hypothalamic-pituitary-adrenal (HPA) axis activity.
Pharmacokinetics: Mometasone furoate monohydrate, administered as an aqueous nasal spray, has a systemic bioavailability of <1% in plasma, using a sensitive assay with a lower quantitation limit (LLOQ) of 0.25 pg/ml. Mometasone furoate suspension is very poorly absorbed from the gastrointestinal tract, and the small amount that may be swallowed and absorbed undergoes extensive first-pass hepatic metabolism prior to excretion in urine and bile.