Pharmacology: Mifepristone is a synthetic steroid with antiprogestational effects indicated for the medical termination of intrauterine pregnancy through 49 days' pregnancy. Doses of 1 mg/kg or greater of mifepristone have been shown to antagonize the endometrial and myometrial effects of progesterone in women. During pregnancy, the compound sensitizes the myometrium to the contraction-inducing activity of prostaglandins. Mifepristone also exhibits antiglucocorticoid and weak antiandrogenic activity. The activity of the glucocorticoid dexamethasone in rats was inhibited following doses of 10 to 25 mg/kg of mifepristone. Doses of 4.5 mg/kg or greater in human beings resulted in a compensatory elevation of adrenocorticotropic hormone (ACTH) and cortisol.
Mechanism Of Action: The anti-progestational activity of mifepristone results from competitive interaction with progesterone at progesterone-receptor sites. Based on studies with various oral doses in several animal species (mouse, rat, rabbit and monkey), the compound inhibits the activity of endogenous or exogenous progesterone. The termination of pregnancy results.
Absorption: The absolute bioavailability of a 20 mg oral dose is 69%
Interactions:
DrugBank: Interactions for Mifepristone
Interactions for Mifepristone:
Although specific drug or food interactions with mifepristone have not been studied, on the basis of this
drugís metabolism by CYP 3A4, it is possible that ketoconazole, itraconazole, erythromycin, and grapefruit
juice may inhibit its metabolism (increasing serum levels of mifepristone). Furthermore, rifampin, dexamethasone, St.
Johnís Wort, and certain anticonvulsants (phenytoin, phenobarbital, carbamazepine) may induce mifepristone
metabolism (lowering serum levels of mifepristone).
Based on in vitro inhibition information, coadministration of mifepristone may lead to an increase in serum
levels of drugs that are CYP 3A4 substrates. Due to the slow elimination of mifepristone from the body, such
interaction may be observed for a prolonged period after its administration. Therefore, caution should be exercised
when mifepristone is administered with drugs that are CYP 3A4 substrates and have narrow therapeutic range, including
some agents used during general anesthesia.
Chemical IUPAC Name: 11-(4-dimethylaminophenyl)-17-hydroxy-13-methyl-17-prop-1-ynyl-1,2,6,7,8,11,12,13,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-3-one
Abortion Drug Adverse Events ReportedDec 30, 2005 FOX News The news set off a new round of calls by abortion opponents for the FDA to remove the drug, also known as Mifeprex, from the market. ...
First Analysis of FDA's Mifepristone Adverse Event ReportsDec 29, 2005 DG News CINCINNATI, OH -- December 29, 1005 -- The abortion drug mifepristone (Mifeprex,TM RU-486), initially touted as a more convenient alternative to surgical ...
Analysis of severe adverse events related to the use of ...Dec 30, 2005 Xagena.it, ...of the FDA's Adverse Event Reporting System ( AERS ) has been performed to assess morbidity and mortality of the abortion drug Mifepristone ( Mifeprex, RU-486 ...
First Analysis Of FDA's Mifepristone Adverse Event ReportsDec 28, 2005 Science Daily (press release) The abortion drug mifepristone (Mifeprex,TM RU-486), initially touted as a more convenient alternative to surgical abortion, has been linked to serious adverse ...
Doctors hit RU-486 reactions, FDA systemDec 28, 2005 United Press International Canada have been linked to RU-486 and questioned whether the FDA system adequately identifies risks from the drug also marketed under the brand name Mifeprex. ...
House Subcommittee Investigates RU-486 Abortion PillDec 22, 2005 Human Events Mifepristone (sold under the brand name Mifeprex) induces abortion medically, and is used as an alternative to surgical abortion in the early stages of ...
Call for ultrasound imaging before using mifepristoneDec 29, 2005 RxPG NEWS, By Annals of Pharmacotherapy, The abortion drug mifepristone (Mifeprex,TM RU-486), initially touted as a more convenient alternative to surgical abortion, has ...
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