SW Dexasone Mechanism of Action

Pharmacology: Pharmacodynamics: Dexamethasone has the capacity to prevent or suppress the development of the local heat, redness, swelling, and tenderness by which inflammation is recognized at the gross level of observation. At the microscopic level, they inhibit not only the early phenomena of the inflammatory process (edema, fibrin deposition, capillary dilatation, migration of phagocytes into the inflamed area, and phagocytic activity) but also the later manifestations (capillary proliferation, fibroblast proliferation, deposition of collagen and still later cicatrization). Naturally occurring glucocorticoids, which also have salt-retaining properties, are used as replacement therapy in adrenocortical deficiency states. Their synthetic analogs, including dexamethasone, are primarily used for their potent anti-inflammatory effects in disorders of many organ systems. Glucocorticoids cause profound and varied metabolic effects. In addition, they modify the body's immune responses to diverse stimuli. At equipotent anti-inflammatory doses, dexamethasone almost completely lacks the sodium-retaining property of hydrocortisone. It is among the most potent glucocorticoids, having about 25-30 times the anti-inflammatory activity of hydrocortisone. In contrast, its effect on electrolytes is slight.
Pharmacokinetics: Dexamethasone is effective when given by mouth and is absorbed from the gastrointestinal tract. The steroid exists in plasma in two forms: a protein-bound form and a free form. The binding is accounted for by two protein fractions. One, "corticosteroid-binding globulin", is a glycoprotein and the other is plasma albumin. The globulin has high affinity but low total binding capacity; the albumin has low affinity but relatively large binding capacity. Consequently, at low or normal concentrations of corticosteroids, most of the hormone is bound to globulin. When the amount of corticosteroid is increased, the concentration of both free and albumin-bound steroid increases with little change in the concentration of that bound to the globulin.