Mifepristone is an antagonist of progesterone ( See “Progesterone and Progestins”. ) but also an antagonist of cortisol and of corticosteroids. Its affinity for the receptor of cortisol is three times more important than that of dexamethasone and it can be used for the treatment of Cushing syndrome. It does not reduce ACTH secretion by the pituitary gland.
