mifepristone, Mifeprex

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GENERIC NAME: mifepristone

BRAND NAME: Mifeprex, Korlym

DRUG CLASS AND MECHANISM: Mifepristone is a synthetic steroid with antiprogesterone and antiglucocorticoid effects. It is used for terminating pregnancy and treating people with Cushing syndrome. Progesterone is a female hormone and the principal progestational hormone. Progesterone prepares the uterus (the womb) to receive and sustain the fertilized egg andis an important hormone for sustaining pregnancy. Mifepristone terminates early pregnancy by blocking the activity of progesterone at progesterone receptors. It also stimulates contraction of the uterus. Early pregnancy is considered to be = 49 days (7weeks) since the last menstrual period began. Mifepristone must be used in combination with misoprostol for the purpose of termination of pregnancy. The FDA approved this combination treatment in September 2000.

Cortisol is a metabolite (break down product) of the hormone cortisone. Cortisol is an essential factor in many processes including the proper metabolism of starches, and it is the major natural glucocorticoid in humans. People with Cushing syndrome produce too much cortisol, and, among many other effects, develop high glucose (sugar) levels in the blood. Mifepristone reduces blood glucose levels in people with Cushing syndrome by blocking the activity of cortisol.

PRESCRIPTION: Yes

GENERIC AVAILABLE: No

PREPARATIONS: Tablets: 200 and 300 mg

STORAGE: Tablets should be stored at room temperature, 15 C - 30 C (59 F - 86 F). Optimal storage temperature is 25 C (77 F).

PRESCRIBED FOR: Mifepristone is used in combination with misoprostol for the termination of intrauterine pregnancy through day 49 of the pregnancy. It also is used for treating Cushing syndrome.

DOSING: Treatment with mifepristone and misoprostol requires three separate office visits.

  • Day 1: Three 200 mg tablets (600 mg) of mifepristone are taken as a single dose.
  • Day 3: 400 mcg of misoprostol is given orally unless abortion has been confirmed.
  • Day 14: No medication administered. Patient returns for a post-treatment examination to confirm that a complete termination of pregnancy has occurred.

The dose for treating Cushing syndrome is 300 mg daily initially. The dose may be increased to 1200 mg daily.

DRUG INTERACTIONS: Ketoconazole, itraconazole (Sporanox), erythromycin, and grapefruit juice may increase blood levels of mifepristone by inhibiting the enzyme responsible for metabolizing (breaking down) mifepristone. Rifampin, dexamethasone, St. John's Wort, phenytoin, phenobarbital, and carbamazepine may decrease blood levels of mifepristone by increasing the activity of the enzyme responsible for metabolizing mifepristone and decrease the effectiveness of mifepristone. Mifepristone may inhibit liver enzymes which are responsible for the metabolism of various drugs, resulting in increased blood levels of these drugs.

Medically Reviewed by a Doctor on 10/30/2014



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