Mifegyne
Overview
Mifegyne (미프진) is an oral medication developed by the French pharmaceutical company Roussel Uclaf; its active ingredient is mifepristone. As an antagonist that binds with high affinity to the progesterone receptor, it blocks the action of progesterone needed to maintain pregnancy in the endometrium and myometrium. Worldwide, it is used in the standard regimen for medication-induced abortion (medical abortion), and it is more commonly used in combination with misoprostol than alone. It was originally a compound studied as a treatment for Cushing's syndrome based on glucocorticoid receptor antagonist activity.
Main content
Mechanism of action
Mifepristone is a synthetic steroid of the 19-norsteroid class and binds strongly to both progesterone receptors and glucocorticoid receptors. Occupying the progesterone receptor blocks progesterone signaling, causing endometrial shedding, inducing uterine contractions, and softening the cervix. At the same time, withdrawal of the progesterone support secreted by the placenta prevents the embryo/fetus from being maintained. Its antiglucocorticoid effect appears at high doses, and this mechanism is the basis for its application in treating Cushing's syndrome.
Development and history
In 1980, researchers at Roussel Uclaf in France (including Étienne-Émile Baulieu) succeeded in developing it, and it was initially called by the code name RU-38486. It was first approved in France in 1988 for abortion, and later expanded to the United Kingdom (1991), Sweden, China, and other countries. In the United States, after political controversy, it received FDA approval in 2000, and since the 2000s it has been introduced in many countries. In South Korea, it has never received formal approval, and social controversy over illegal online distribution has repeatedly occurred.
Indications and usage
Its main indication is early abortion within 10 weeks (70 days) of gestation. Typically, 200 mg of mifepristone is taken orally once, and 24–48 hours later, 800 μg of misoprostol is administered buccally or sublingually. It is in principle carried out under the supervision of a medical institution, and after administration, bleeding and pain should be monitored and complete abortion should be confirmed. In addition, it is used exploratorily for uterine fibroid shrinkage, Cushing's syndrome, and some research on breast cancer and meningioma.
Safety and side effects
Common adverse reactions include abdominal cramps, vaginal bleeding, nausea, vomiting, diarrhea, headache, fever, and dizziness. Rarely, serious complications such as heavy bleeding, intrauterine infection, and sepsis may occur, and in cases of incomplete abortion, additional curettage or repeat dosing may be required. Contraindications include ectopic pregnancy, chronic adrenocortical insufficiency, bleeding disorders and anticoagulant use, and certain drug interactions. Adrenal suppression has also been reported with long-term high-dose exposure.
Regulatory status
After its first approval in France, it was authorized in many European countries, the United States, China, India, and elsewhere. In contrast, in South Korea and during certain periods in Japan, it was not approved or was only restrictively accessible. In South Korea, even after the Constitutional Court's 2020 ruling that the abortion crime was unconstitutional, related legislation has not been reorganized, and there have been continuing criticisms that the drug approval and distribution issues remain in a legal vacuum.
Recent trends
In 2024, the U.S. Supreme Court unanimously dismissed a lawsuit seeking to invalidate the approval of mifepristone, without recognizing the plaintiffs' standing, so the FDA approval itself was maintained. The FDA had previously abolished the in-person dispensing requirement in 2021, allowing telemedicine prescriptions and mail delivery, and as a result, access within the United States expanded significantly. At the same time, in 2024, some states, such as Louisiana, classified mifepristone as a controlled substance, strengthening state-level regulation and deepening disparities in access by state. In 2025 as well, legal conflicts between the federal government and states continue over telemedicine prescribing, interstate 'shield laws,' and mail delivery, while in some European and South American countries, the trend of deregulation and expanded free provision continues. In South Korea, discussions are underway among the medical community, legal circles, and civil society over whether to approve it and how to prevent misuse.
Related topics
- [[미소프로스톨]]
- [[임신 중절]]
- [[의약품 허가]]
- [[여성 건강]]
- [[헌법재판소 낙태죄 결정]]