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Mifepristone is a pill that can be taken as an alternative to a surgical abortion.


This medication most often is used for ending early pregnancies. In 2003, studies were surfacing reporting other possible uses for mifepristone, at least at low doses. These studies included its possible use in treating psychotic depression. Low-dose mifepristone also showed success as a treatment for uterine fibroids, or benign growths in the muscular tissue of a woman's uterus. However, many uses of the drug other than for abortions were still experimental, even if promising.
Mifespristone's primary use for medical abortions is preferred by many over surgical approaches to abortions. It has emerged as a form of emergency contraception when taken at low does within a short time period following possible conception.


Women who are more than seven weeks pregnant (or 49 days since their last menstrual period) should not take mifepristone. Other reasons to avoid mifepristone include: use of an intrauterine device (IUD), ectopic pregnancy, use of blood thinners, bleeding disorders, use of steroid medications, allergies to mifepristone or similar drugs and lack of access to medical help within two weeks after the treatment. When the drug is used at low doses as emergency contraception, it poses few side effects.


Mifepristone, sold commercially under the name Mifeprex, also is known as RU-486, the abortion pill, the early option pill for medical abortion. While it has been used for many years in Europe, mifepristone has only been available for use in the United States since the U.S. Food and Drug Administration (FDA) approved it in 2000 for use in abortion. More than 37,000 abortions were performed using the pill in the first six months of 2001.
This drug causes pregnancy to end by blocking the female hormone progesterone. The lack of progesterone makes the uterus shed its lining, which causes bleeding similar to a menstrual period. Three days after taking mifepristone, women are given a second drug, misprostol, to cause uterine contractions that expel the contents of the uterus. Most women are able remain in their own home while they pass the fetus.


Before taking mifepristone, health care providers likely will give the woman a urine or blood test to be sure that she is, in fact, pregnant. They also may give her some counseling and support. Once she has made the decision to use mifepristone, they will ask her to sign a written statement that she has decided to end her pregnancy.


Using mifepristone and misoprostol causes heavy bleeding and cramping. Doctors can offer pain medicine, such as Motrin, to ease the cramps. For two weeks after treatment with mifepristone, health care providers likely will ask patients to abstain from sexual intercourse, heavy lifting and strenuous exercise. They also may advise against breast-feeding, since scientists are not sure if the drug is present in breast milk.
Physicians require patients to come in for a follow-up visit 14 days after their first dose of mifepristone to verify that they are no longer pregnant and that they are properly healing.


Other common side effects include: fatigue, headaches, dizziness, nausea, vomiting, diarrhea and low-back pain.
Since pregnancy hormones are in flux after a medical abortion, many women have emotional side-effects, such as mood swings, depression or a mild case of the blues. These feelings usually subside when hormones stabilize a few weeks later. For those who feel stuck in their grief or anger about the situation, counseling or support groups may offer relief.

Normal results

Most women feel better after about two weeks. Bleeding and spotting usually occurs for 9-16 days, but may last for a month.

Abnormal results

In some cases, mifepristone does not completely end the pregnancy. If the fetus is still left inside the uterus, a doctor may recommend a surgical abortion, or a procedure called dilation and curettage (D and C). About five to eight of every 100 women who take mifepristone go on to have a surgical abortion, according to the FDA. During a D and C, which usually is done at a hospital or clinic under a local anesthetic, a physician dilates the cervix, then uses an instrument to scrape any residual tissue away from the walls of the uterus. This allows the heavy bleeding to eventually stop so a woman can return to her normal cycle sooner.

Key terms

Dilation and curettage (D and C) — During this surgical procedure, a physician dilates the cervix, then uses an instrument to scrape tissue away from the walls of the uterus.
Misprostol — A drug used in combination with mifepristone to cause uterine contractions that expel the contents of the uterus.



"Abortion Pills Account For 5% of U.S. Abortions." Medical Letter on the CDC and FDA February 9, 2003: 7.
"The Abortion Pill's Grim Progress." Mother Jones 24 (January 1, 1999).
Grimes, David A, Mitchell D. Creinin. "Induced Abortion: an Overview for Internists." Annals of Internal Medicine April 20, 2004: 620-627.
"Low-dose Mifepristone Blocks Pregnancy by Altering Ovarian Function." Drug Week March 5, 2004: 107.
"Treatments for Depression with Psychosis." Harvard Mental Health Letter August 2003.
Walling, Anne D. "Low-dose Mifepristone Shrinks Uterine Fibroids." American Family Physician September 1, 2003: 956.


an antiprogestin used with misoprostol or other prostaglandin to terminate pregnancy in the first trimester; administered orally. Called also RU-486.

mifepristone (RU-486)

Korlym, Mifegyne (UK), Mifeprex

Pharmacologic class: Synthetic steroid

Therapeutic class: Antiprogestational agent, abortifacient

Pregnancy risk category NR

FDA Box Warning

• Rare cases of serious and sometimes fatal infections and bleeding have followed spontaneous, surgical, and medical abortions, including after mifepristone use. Before starting drug, inform patient of risk of these serious events and discuss medication guide and patient agreement. Ensure that patient knows whom to call and what to do, including going to emergency department (ED) if none of provided contacts are reachable; if she experiences sustained fever, severe abdominal pain, prolonged heavy bleeding, or syncope; or if she has abdominal pain or discomfort or general malaise (including weakness, nausea, vomiting, or diarrhea) more than 24 hours after taking drug.

• Patients with serious bacterial infections and sepsis may present without fever, bacteremia, or significant pelvic examination findings after abortion. Rare deaths have occurred in patients without fever, with or without abdominal pain, but with leukocytosis with marked left shift, tachycardia, hemoconcentration, and general malaise. Maintain high index of suspicion to rule out serious infection and sepsis.

• Advise patient to take medication guide with her if she visits ED or another health care provider who didn't prescribe drug, so provider will be aware that patient is undergoing medical abortion.

• Be aware that pregnancy must be excluded before initiation of treatment with Korlym. Patients must avoid pregnancy during treatment and for 1 month after therapy ends by using a nonhormonal, medically acceptable method of contraception; if patient has had a surgical sterilization, no additional contraception is needed. Pregnancy must also be excluded if treatment is interrupted for more than 14 days in females of childbearing potential.


Antagonizes progesterone receptor sites, inhibiting activity of endogenous and exogenous progesterone and stimulating uterine contractions, which causes fetus to separate from placental wall


Tablets: 200 mg, 300 mg

Indications and dosages

Termination of intrauterine pregnancy through day 49 of pregnancy

Adults: On day 1, mifepristone 600 mg P.O. as a single dose. On day 3, misoprostol 400 mcg P.O. (unless abortion has been confirmed).

Hyperglycemia secondary to hypercortisolism in adults with endogenous Cushing's syndrome who have type 2 diabetes or glucose intolerance and have failed surgery or aren't candidates for surgery

Adults: Initially, 300 mg P.O. daily; increase based on clinical response and tolerability in 300-mg increments to a maximum of 1,200 mg daily. Don't exceed 20 mg/kg/day.

Dosage Adjustment

• Renal impairment (Korlym)
• Mild to moderate hepatic impairment (Korlym)
• Concurrent use of strong P450 CYP3A inhibitors (Korlym)


• Hypersensitivity to drug, misoprostol, or other prostaglandins
• Confirmed or suspected ectopic pregnancy or adnexal mass
• Chronic adrenal failure
• Bleeding disorders
• Concurrent anticoagulant therapy or long-term corticosteroid therapy
• Presence of intrauterine device (IUD)
• Inherited porphyrias
• Concomitant treatment with systemic corticosteroids for serious medical conditions or illnesses (Korlym)
• Concurrent use of simvastatin or lovastatin and CYP3A substrates with narrow therapeutic range (Korlym)
• History of unexplained vaginal bleeding or endometrial hyperplasia with atypia or endometrial carcinoma (Korlym)
• Pregnancy (Korlym)


Use cautiously in:
• cardiovascular, respiratory, renal, or hepatic disorders; hypertension; type 1 diabetes mellitus; anemia; jaundice; seizure disorder; cervicitis; infected endocervical lesions; acute vaginitis; uterine scarring
• hypokalemia, underlying heart conditions including heart failure and coronary vascular disease (Korlym)
• hemorrhagic disorders or concurrent use of anticoagulants (Korlym)
• concurrent use of QT interval-prolonging drugs, patients with potassium channel variants resulting in long QT interval (avoid Korlym use)
• concurrent use of drugs metabolized by CYP2B6 and moderate CYP3A inhibitors (Korlym)
• concurrent use of CYP3A inducers (such as rifampin, rifabutin, rifapentin, phenobarbital, phenytoin, carbamazepine, and St. John's wort) or hormonal contraceptives (avoid use)
• concurrent use of strong CYP3A inhibitors (use Korlym with extreme caution and only when necessary; limit dosage to 300 mg)
• concurrent use of drugs metabolized by CYP2C8/2C9 (use lowest dose of CYP2C8/2C9 substrates when used with Korlym)
• breastfeeding patients (Korlym)
• children (Korlym; safety and efficacy not established).


• Before giving dose for termination of pregnancy, make sure patient doesn't have an IUD in place.
• Correct hypokalemia before starting Korlym.
• Give for termination of pregnancy only in health care facility under supervision of health care provider qualified to assess pregnancy stage and rule out ectopic pregnancy.
• Administer with fluids, but not with grapefruit juice.
• When giving for termination of pregnancy, confirm pregnancy termination 14 days after initial dose.

Adverse reactions

CNS: dizziness, fainting, headache, weakness, fatigue, insomnia, asthenia, anxiety, syncope, rigors

CV: hypertension, QT-interval prolongation (Korlym)

EENT: sinusitis

GI: nausea, vomiting, diarrhea, abdominal cramping, dyspepsia

GU: vaginitis, leukorrhea, uterine cramping, pelvic pain; endometrial hypertrophy, cystic dilatation of endometrial glands, vaginal bleeding (Korlym); uterine hemorrhage

Hematologic: anemia

Metabolic: hypokalemia, adrenal insufficiency (Korlym)

Musculoskeletal: leg pain, back pain, arthralgia

Skin: rash (Korlym)

Other: viral infections; fever, decreased appetite, peripheral edema, opportunistic infections (Korlym)


Drug-drug.CYP2C8/2C9 substrates: increased plasma concentrations of these drugs

CYP3A inducers (such as carbamazepine, phenobarbital, phenytoin, rifabutin, rifampin, rifapentin): decreased mifepristone concentrations

CYP3A substrates with narrow therapeutic range (such as cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, tacrolimus): increased exposure of these drugs and effects

Drugs metabolized by CYP2B6 (bupropion, efavirenz): significantly increased exposure of these drugs

Drugs metabolized by CYP3A (lovastatin, simvastatin): increased risk of myopathy and rhabdomyolysis

Glucocorticoids: antagonized glucocorticoid effect

Moderate CYP3A inhibitors (such as amprenavir, aprepitant, atazanavir, ciprofloxacin, darunavir/ritonavir, diltiazem, erythromycin, fluconazole, imatinib, verapamil), strong CYP3A inhibitors (such as amprenavir, boceprevir, clarithromycin, conivaptan, fosamprenavir, indinavir, itraconazole, lopinavir, mibefradil, nefazodone, nelfinavir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, voriconazole): increased plasma mifepristone concentration

Oral contraceptives: decreased oral contraceptive effectiveness

Drug-diagnostic tests.Hematocrit, hemoglobin: decreased values

Potassium: decreased level

Red blood cells: decreased count

Drug-food.Grapefruit juice: increased mifepristone blood level and effects

Drug-herbs.St. John's wort: decreased mifepristone blood level and effects

Patient monitoring

• Assess vital signs, breath sounds, and bowel sounds.
• Monitor uterine contractions and type and amount of vaginal bleeding.
• Evaluate CBC.
• Monitor serum potassium level 1 to 2 weeks after starting or increasing Korlym dosage and periodically thereafter.

Closely monitor patient taking Korlym for signs and symptoms of adrenal insufficiency, including weakness, nausea, increased fatigue, hypotension, and hypoglycemia. If adrenal insufficiency is suspected, discontinue drug immediately and administer glucocorticoids without delay. May resume Korlym at a lower dosage after resolution of adrenal insufficiency.
• Be aware that patients with endogenous Cushing's syndrome are at risk for opportunistic infections such as Pneumocystis jiroveci pneumonia while taking Korlym. Monitor patient for respiratory distress shortly after Korlym initiation. Initiate appropriate diagnostic tests and treat P. jiroveci as indicated.

Patient teaching

When used for termination of pregnancy:
• After administration, tell patient she will need to return in 48 hours for a prostaglandin drug or to verify pregnancy termination.
• Tell patient she will have contractions for 3 or more hours after receiving drug and that vaginal bleeding may last 9 to 16 days.

Instruct patient to contact prescriber if she has persistent or extremely heavy vaginal bleeding, extreme fatigue, or orthostatic hypotension.

Caution patient that vaginal bleeding does not prove that complete abortion has occurred. Tell her she will need follow-up appointment 2 weeks later to verify pregnancy termination.
• Inform patient that she is at risk for pregnancy right after abortion is complete. Encourage appropriate contraceptive decision.

When used for hyperglycemia secondary to hypercortisolism in patients with endogenous Cushing's syndrome:

Instruct patient to recognize and report signs and symptoms of hypokalemia, respiratory infections, and adrenal insufficiency.
• Advise patient not to take drug with grapefruit juice and not to use herbal products without consulting prescriber.

When used for either indication:
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.


Synthetic chemical compound with antiprogesterone properties used for early pregnancy termination; the substance binds with glucocorticoid receptors resulting in increased adrenal gland secretion.
Synonym(s): RU-486


/mif·e·pris·tone/ (mĭf″ĕ-pris´tōn) RU-486; an antiprogestin used with misoprostol or other prostaglandin to terminate pregnancy in the first trimester.


an antiprogestin used with misoprostol or other prostaglandins that induces abortion if taken within the first 7 weeks of pregnancy. Two days after taking the drug to end the pregnancy, the woman must take a second drug to cause strong uterine contractions that expel the fetus. Mifepristone is reportedly effective 95.5% of the time, and serious complications are rare. However, the procedure may be somewhat painful, and a small percentage of patients have required blood transfusions. If the drug regimen fails to terminate the pregnancy, the woman must arrange for a surgical abortion to complete the process. Also called abortion pill, RU-486.


An antiprogestin used with misoprostol, a PGE1 analogue, as a morning-after contraceptive for early pregnancy termination.


RU 486 Obstetrics An antiprogestin used as a morning-after contraceptive, with misoprostol, a PGE1 analogue, for early pregnancy termination. Cf Late abortion.


(RU-486) (mif'ĕ-pris-tōn)
Synthetic chemical compound with antiprogesterone properties used for early pregnancy termination.
Synonym(s): RU-486.


A progesterone antagonist drug also known as RU-486. When given in early pregnancy mifepristone causes the detachment of the blastocyst, the production of prostaglandins that prompt contraction of the womb and softening of the cervix. The result is abortion of the conceptus. A brand name is Mifegyne.


a compound with antiprogesterone and antiglucocorticoid activity. Used as an abortifacient and in the management of hyperadrenocorticism.
References in periodicals archive ?
The FDA protocol involved 600 milligrams of mifepristone followed by 400 micrograms of misoprostol taken orally at a return visit to the clinic two days after the first.
2) In most cases, the women are using misoprostol alone, without mifepristone, to cause an abortion.
Also, there was no significant differences in success rate when misoprosotol was prescribed in combination with mifepristone in first trimester [29].
Eve Espey said that fewer side effects are seen with buccal or vaginal administration of misoprostol compared with taking the drug orally, and that the lower dose of mifepristone in the Continued on following page alternative regimen also may reduce side effects.
While mifepristone and Plan B, medications with proven safety records, have encountered significant barriers to market entry, the IIPV vaccine Gardasil "has held a privileged position in the history of US state and market treatment of women's reproductive drugs," according to Haussman.
However, to facilitate comparisons with international experience with such regimens for medication abortion, all women were asked to provide a urine sample for laboratory analyses prior to administration of mifepristone.
Where mifepristone is not available, for pregnancies up to 12 weeks, the recommended medical method is 800 [micro]g of misoprostol, administered vaginally or sublingually.
Our expectation is that mifepristone is contributing to that trend.
Both ulipristal and mifepristone block the key early pregnancy hormone, progesterone, from functioning properly which effectively starves the embryo.
Activists have called for removal of mifepristone (Mifeprex) from the U.
The abortion pills mifepristone and misoprostol are taken two days apart under medical supervision and the termination takes place a few hours later.
For a medical abortion, a woman takes a tablet of the drug mifepristone under supervision before returning two days later to take four pills of misoprostol.