Dexamethasone - a synthetic<unk>  binds more powerfully to the<unk>  receptor than cortisol does. Dexamethasone is based on the cortisol structure but differs at three positions (extra double bond in the A-ring between carbons 1 and 2 and addition of a 9-α-fluoro group and a 16-α-methyl substituent). A variety of synthetic<unk> s, some far more potent than cortisol, have been created for therapeutic use. They differ in both pharmacokinetics (absorption factor, half-life, volume of distribution, clearance) and pharmacodynamics (for example the capacity of mineralocorticoid activity: retention of sodium (Na+) and water; renal physiology). Because they permeate the intestines easily, they are administered primarily per os (by mouth), but also by other methods, such as topically on skin. More than 90% of them bind different plasma proteins, though with a different binding specificity. Endogenous<unk> s and some synthetic corticoids have high affinity to the protein transcortin (also called corticosteroid-binding globulin), whereas all of them bind albumin. In the liver, they quickly metabolize by conjugation with a sulfate or glucuronic acid, and are secreted in the urine.<unk>  potency, duration of effect, and the overlapping mineralocorticoid potency vary. Cortisol is the standard of comparison for<unk>  potency. Hydrocortisone is the name used for pharmaceutical preparations of cortisol. The data below refer to oral administration. Oral potency may be less than parenteral potency because significant amounts (up to 50% in some cases) may not reach the circulation. Fludrocortisone acetate and deoxycorticosterone acetate are, by definition, mineralocorticoids rather than<unk> s, but they do have minor<unk>  potency and are included in this table to provide perspective on mineralocorticoid potency. + Comparative oral corticosteroid potencies Name<unk>  potency Mineralocorticoid potency Terminal half-life (hours) Cortisol (hydrocortisone) 1 1 8 Cortisone 0.8 0.8 8 Prednisone 3.5–5 0.8 16–36 Prednisolone 4 0.8 16–36 Methylprednisolone 5–7.5 0.5 18–40 Dexamethasone 25–80 0 36–54 Betamethasone 25–30 0 36–54 Triamcinolone 5 0 12–36 Deflazacort 6.5 - 1.3 Fludrocortisone acetate 15 200 24 Deoxycorticosterone acetate 0 20 - Aldosterone 0.3 200-1000 - Beclometasone 8 sprays 4 times every day equivalent to orally 14 mg prednisone once a day - -
Glucocorticoid
Adrenal steroid
Corticosteroid
Antiglucocorticoid
Xenohormone
Anticorticotropin
Phytosteroid
Neurohormone