pms-Dexamethasone Mechanism of Action

Pharmacotherapeutic group: corticosteroids for systemic use, glucocorticoids. ATC code: H02AB02.
Pharmacology: Pharmacodynamics: Mechanism of action: Dexamethasone is a highly potent and long-acting glucocorticoid with negligible sodium retaining properties and is therefore, particularly suitable for the use in patients with cardiac failure and hypertension.
Its anti-inflammatory potency is 7 times greater than prednisolone and, like other glucocorticoids, dexamethasone also has anti-allergic, antipyretic and immunosuppressive properties.
Dexamethasone has a biological half-life of 36 - 54 hours and therefore is suitable in conditions where continuous glucocorticoid action is required.
Pharmacokinetics: Absorption and Distribution: Dexamethasone is well absorbed when given by mouth; peak plasma levels are reached between 1 and 2 hours after ingestion and show wide interindividual variations. The mean plasma half-life is 3.6 ± 0.9 h. Dexamethasone is bound (to about 77%) to plasma proteins, mainly albumins. Percentage protein binding of dexamethasone, unlike that of cortisol, remains practically unchanged with increasing steroid concentrations. Corticosteroids are rapidly distributed to all body tissues. They cross the placenta and may be excreted in small amounts in breast milk.
Biotransformation: Dexamethasone is metabolised mainly in the liver but also in the kidney.
Elimination: Dexamethasone and its metabolites are excreted in the urine.
Toxicology: Preclinical safety data: Studies in animals have shown that glucocorticoids increase the incidence of cleft palate, spontaneous abortions and intrauterine growth retardation. In some cases these divergences were combined with defects of the central nervous system and of the heart. In non-human primates, minor cranial skeletal abnormalities were observed. These effects were observed after use of high doses of dexamethasone.