Pharmacology of the corticosteroids is complex and the drugs affect almost all body systems. Maximum pharmacologic activity lags behind peak blood concentrations, suggesting that most effects of the drugs result from modification of enzyme activity rather than from direct actions by the drugs.
Most glucocorticoids appear to be readily absorbed when administered orally.
Prednisone is rapidly converted to prednisolone, but much of cortisone is inactivated before it can be converted to hydrocortisone. Pharmacologically active glucocorticoids are metabolized primarily in the liver, to biologically inactive compounds. Inactive metabolites are excreted by the kidneys. Small amounts of unmetabolized drugs are also excreted in urine. Adverse Effects Short-term administration of glucocorticoids, even in massive dosages, is unlikely to produce harmful effects.