The “abortion pill” is the popular name for a safe and effective way to end an early pregnancy using a combination of two medicines: mifepristone and misoprostol. Mifepristone stops the pregnancy from growing. After taking mifepristone, you take a second medicine (misoprostol) up to 48 hours later. Includes Mifepristone indications, dosage/administration, pharmacology, mechanism/onset/duration of action, half-life, dosage forms, interactions, warnings, adverse reactions, off-label uses and more. 1.2Cushing's syndrome. 1.3Medical management of early pregnancy loss. 1.4Other uses. 2Side effects. Toggle Side effects subsection. 2.1Pregnancy. 3Pharmacology. Mifeprex selectively blocks progesterone via the progesterone receptor at low doses and when used to terminate a pregnancy, Mifeprex works by competing with progesterone at progesterone-receptor sites. What is mifepristone and how does it work? Mifepristone is a drug that blocks a hormone called progesterone that is needed for a pregnancy to continue. Overview: Mifepristone is an oral tablet used to end a pregnancy during the first 10 weeks of pregnancy. Mifepristone works by blocking a hormone needed to maintain a pregnancy. Common side. Mifepristone (Mifeprex) is an oral tablet that may be used with misoprostol tablets to end a pregnancy that is 10 weeks or less (70 days or less since the start of your last period). Mifepristone (Mifeprex) is a synthetic steroid used to terminate early pregnancy. The Korlym brand of mifepristone is a cortisol receptor blocker, used to manage and treat high blood glucose levels (hyperglycemia) in people with Cushing’s syndrome. Mifepristone, also called “the abortion pill,” is a U.S. FDA-approved oral medication used—along with misoprostol—in a two-drug regimen to end a pregnancy up to 70 days into gestation. Mifepristone is used in a regimen together with misoprostol to end a pregnancy that is less than 70 days in duration. It works by stopping the supply of hormones that maintains the interior of the uterus.