Inhibits adrenocortical steroid synthesis by blocking the production of adrenal glucocorticoids, mineralocorticoids, estrogens, and androgens.

Suppression of adrenal function in patients with Cushing’s syndrome. Unlabeled use: To cause “chemical adrenalectomy” in patients with advanced breast cancer and patients with metastatic prostate cancer.

Well absorbed orally and excreted in the urine. Half-life: 11 to 16 hours.

♦ Adult: Initial dose is 250 mg/day PO at 6-hour intervals. If cortisol suppression is not adequate, the dosage
may be increased in increments of 250 mg/day at 1- to 2-week intervals to a total daily dose of 2 g. If adverse side effects occur, including extreme drowsiness or a skin rash that persists for 5 days or longer or becomes severe, or if the patient develops excessively low cortisol levels, reduce the dose or discontinue the drug.