Mifepristone

Mifepristone is an antagonist of glucocorticoid, progesterone, and androgen receptors (Kis = 0.1, 0.64, and 0.65 nM, respectively).{41967,41968,40657} It is selective for these receptors over the mineralocorticoid receptor (MR), estrogen receptor ? (ER?), and ER? (Kis = 640, >200, and >750 nM, respectively).{41967} In cell-based assays, mifepristone inhibits alkaline phosphatase activity stimulated by the progesterone receptor agonist R5020 as well as reporter transcription stimulated by either dexamethasone (Item No. 11015) or R5020 (IC50s = 7, 5.9, and 1.3 nM, respectively).{40657} It also inhibits synthetic androgen R1881-stimulated reporter transcription in a concentration-dependent manner.{41968} Mifepristone (10 µM) inhibits growth of 4-OHT-resistant MCF-7 breast cancer cells in vitro.{12451} It also inhibits tumor growth in an SKOV3 ovarian cancer nude mouse xenograft model when administered at doses of 0.5 or 1 mg per day.{41969} Formulations containing mifepristone have been used for the induction of medical abortions.