Glucocorticoid relative potencies

The relative potencies for glucocorticoid and mineralocorticoid (sodium-retaining) effects which are shown in Table 34.1 are central to the choice of agent in relation to clinical indication. 

There are three aerosolized corticosteroid preparatioias available in MDI formulation for administration to horses via the Equine AeroMask beclometasone dipropionate, fluticasone propionate and flunisolide (Table 16.2). In terms of the relative potency, fluticasone is more potent than beclometasone, which is more potent than flunisolide, which is equipotent to triamcinolone. Using dexamethasone as the standard (1.0), the relative glucocorticoid receptor affinity of the common corticosteroids is flunisolide 1.9, triamcinolone 2.0, beclometasone (active metabolite) 13.5 and fluticasone propionate 22.0 (Barnes et al 1998). The pulmonary residence time of the aerosolized corticosteroids is determined by the lipophilicity of each drug. Flunisolide has intermediate water solubility (lOmg/ml), simitar to... 

Corticosteroids traditionally are divided into mineralocorticoids and glucocorticoids according to their relative potencies in Na retention and effects on carbohydrate metabolism i.e., hepatic deposition of glycogen and gluconeogenesis) In general, potencies of steroids to sustain life in adrenalectomized animals closely parallel their mineralocorticoid activity, while potencies as antiinflammatory agents closely parallel their effects on glucose metabolism. The effects on Na" retention and the carbohydrate/anti-inflammatory actions are not closely related and reflect selective actions at distinct receptors. 

Compound Glucocorticoid potency relative tohydrocortisone Mineralocorticoid potency Equivalent doses (mg)... 

The fluorinated glucocorticoids are said to have relatively more catabolic activity than others and might have a greater effect on the skeleton but such impressions may merely reflect the general potency of some newer glucocorticoids and a tendency to use them in inappropriate doses. A relatively new glucocorticoid, deflazacort, has been proposed to have less effect on bone metabolism, but a double-blind study has failed to show an advantage compared with prednisolone (SEDA-21, 417 194). 

These drugs are both topical glucocorticoids. However, desonide has relatively low potency, whereas desoximetasone is a high-potency drug. 

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