The direct effects of etomidate, ketoconazole, miconazole and metyrapone were investigated on the secretion of cortisol and its precursors by dispersed cells from the adrenal cortex of a normal individual and four patients with Cushing's syndrome. The drugs interfered with adrenocorticotropic hormone-stimulated cortisol secretion in a dose-dependent way. Desoxycortisol concentrations in the medium were increased after the addition of metyrapone and low doses of etomidate but were suppressed with higher doses of etomidate. The production of 17-hydroxy-progesterone was stimulated by miconazole and metyrapone but was strongly suppressed by the high doses of etomidate. Ketoconazole caused a stimulation of progesterone release, whereas the release of 17-hydroxyprogesterone was suppressed. Finally, the concentration of progesterone was strongly enhanced with high doses of miconazole, whereas etomidate suppressed progesterone production. It is concluded that etomidate at a low concentration (IC50, 10(-8) M) inhibits 11 beta-hydroxylase, whereas, at higher concentrations (10(-7)-10(-6) M), the side-chain cleavage enzyme system is also inhibited; metyrapone is a weaker (IC50, 10(-7) M) but pure 11 beta-hydroxylase inhibitor; miconazole inhibits adrenal 21-hydroxylase at 10(-6) M; and ketoconazole inhibits 17-hydroxylase. Etomidate, ketoconazole, miconazole and metyrapone inhibit cortisol biosynthesis in the human adrenal gland in different manners, which appear to involve the four cytochrome P-450-dependent monooxygenase reactions. Interestingly, these drugs affect corticosteroidogenesis by normal, hyperplastic and adenomatous adrenal cells in a similar manner.