The effect of ketoconazole on steroidogenesis in cultured mouse adrenal cortex tumor cells.

The effects of the antimycotic agent ketoconazole on steroid biosynthesis in adrenal cells was investigated in monolayer cultures of functional mouse adrenal cortex tumors. Ketoconazole inhibits ACTH-stimulated steroidogenesis to below non-stimulated levels at concentrations of 1.0 μg/ml or higher. Half maximal inhibition occurs at a concentration of 0.3 μg/ml. These drug levels are in the therapeutic range achieved by oral administration in human subjects. The inhibitory effects of 3.3 μg/ml or less of ketoconazole are totally reversible within the first hour after removal of the agent. Exposure of the cultures to high concentrations of ketoconazole for periods of 24–48 hours is not toxic to the cells, with a resumption of steroidogenic activity within several hours after its removal. Cyclic AMP-stimulated steroidogenesis is also inhibited by this agent, but it has no effect on ACTH-stimulated cAMP production in these cultures. Ketoconazole is an even more potent inhibitor of 11β hydroxylation in these c...