Metyrapone is a drug that inhibits the production of CORTISOL in the adrenal cortex, which results in an increase in ACTH production and (completing the feedback control cycle) thus greater synthesis of the chemical precursors of cortisol. Metyrapone is used to treat patients with CUSHING’S SYNDROME (a condition caused by excess amounts of corticosteroid hormones in the body) where surgery is not possible.