Drenex Mechanism of Action

Pharmacology: Pharmacodynamics: Dexamethasone is a highly potent and long-acting glucocorticoid whose main pharmacological actions include: (a) general effects on metabolism, water and electrolyte imbalance; (b) negative feedback effect on the hypothalamus and pituitary glands; (c) anti-inflammatory and immunosuppressive effects. It has negligible sodium-retaining properties and has powerful anti-inflammatory and immunosuppressive effects.
Pharmacokinetics: Dexamethasone is well absorbed orally. Peak plasma levels are reached between 1 to 2 hours after ingestion. The area under the curve (AUC), volume of distribution, plasma clearance, and maximum plasma concentration are not dose-dependent but vary by a factor of about 0.6-0.7 after oral doses of 0.5-1.5 mg. The systemic bioavailability of dexamethasone is approximately 90% and the mean plasma half-life is 3.6 ± 0.9 hours. Up to 77% of dexamethasone is bound to plasma proteins. Percentage binding of dexamethasone, unlike that of cortisol, remains practically unchanged with increasing steroid concentrations.
Dexamethasone's metabolism in the liver is slow and limited and 60% of the administered dose is excreted in the urine within 24 hours largely as unconjugated steroids. Dexamethasone's plasma half-life is shortened in chronic renal failure. Metabolic clearance is reduced and plasma half-life is prolonged in patients with liver disease, Dexamethasone is cleared more rapidly from the circulation of the fetus and neonate than in the mother.