1. E. Recovery from prolonged steroid therapy is slow, and the withdrawal may be unpleasant. The patient may be reluctant to reduce the dose of steroid because of its salutary effects on the psyche. Tapering the dose of steroid is important in steroid withdrawal; however, the patient may temporarily require a dose increase during periods of heightened stress.
2. A. 17,20 lyase is required for androgen synthesis, cyclooxygenase for prostaglandin production, 11-p-hydroxysteroid dehydrogenase-2 acts as a reduc-tase-converting cortisol to its inactive 11-keto derivative cortisone, whereas 18-hydroxylase is required for aldosterone production.
3. A. Glucocorticoid treatment of rheumatoid arthritis does not eradicate all symptoms, nor does it reverse the degenerative process. Suppression of the hypothalamic-pituitary-adrenal axis is an unwanted side effect of glucocorticoid therapy. While development of a sense of well-being may be attributed to the relief of symptoms, it is not the primary basis for employing the potent glucocorticoids.
4. B. The addition of a fluoride group to ring C of cortisol to give 9-a-fluorocortisol greatly increases and prolongs all biological activity. The result is an agent with potent glucocorticoid and mineralocorti-coid activity, making it inappropriate to use in rheumatoid arthritis. Because of its potency and extended action, fluorocortisol will have a greater tendency to depress the hypothalamic-pituitary axis than cortisol, even when applied topically.
5. D. Dexamethasone is a fluorinated glucocorticoid that is more potent and longer acting than cortisol. While devoid of salt-retaining activity in therapeutic doses, this glucocorticoid does possess most of the adverse effects observed with cortisol. Because it lacks mineralocorticoid activity, dexamethasone is not used in replacement therapy.
6. D. In addition to its ability to block steroid biosynthesis, ketoconazole is frequently used as an antifungal agent. Its action is readily reversible and is used principally for interim management of Cushing's disease prior to surgery or radiotherapy. Ketoconazole preferentially blocks the C17,20 lyase reaction that is involved in the synthesis of sex steroids.
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