Antiprogestins, selective progesterone receptor modulators
ATC code: G03XB01 (Mifepristone)
Brand names
Mifeprex, Korlym (для синдрома Кушинга)
Selective antagonist of progesterone and glucocorticoid receptors. Blockade of endometrial progesterone receptors causes decidual necrosis, gestational sac detachment, cervical softening, and increased myometrial sensitivity to prostaglandins. Combined with misoprostol (a synthetic prostaglandin E1 analog, 24–48 hours after mifepristone), it provides medical abortion up to 12 weeks. Efficacy 95–98 % with proper use.
First line
First-line for medical abortion per 2022, 2020, 2015. Standard regimen – mifepristone 200 mg orally, then misoprostol 800 mcg buccally, sublingually, or vaginally 24–48 hours later. Up to 9 weeks: 95–98 % efficacy; 9–12 weeks: up to 95 % with possible repeat misoprostol doses. After 12 weeks – higher-dose regimens or surgical methods. Alternative – vacuum aspiration. WHO classifies medical abortion as primary care and supports access.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Mifepristone is an antiprogestin and contraindicated when continuing pregnancy is desired. Off-protocol or impromptu use is unacceptable. In a patient with cramping or spotting in a wanted pregnancy, mifepristone is not indicated and is hazardous.
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Boxed warning
FDA boxed warning: serious and sometimes fatal infections and bleeding after medical abortion. Patients must have access to emergency medical care for several days after misoprostol. Symptoms of serious complications require urgent hospital evaluation.
Indicated for pregnancy termination; contraindicated when continuing pregnancy is desired. After failed medical abortion with continued pregnancy — increased teratogenicity risk (Möbius syndrome from misoprostol); informed decision-making is offered.
Transfers into milk in small amounts. After a single dose, no feeding interruption is needed; with repeat dosing, skip feeds for 12 hours.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Mifepristone is evaluated for the following indications with varying evidence strength: Medical abortion (evidence tier A), Threatened miscarriage (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Mifepristone (≥ 1 in 100): Vaginal bleeding (part of expected effect), Abdominal cramping, Nausea, vomiting, Diarrhea (from misoprostol), Fatigue, Headache. See the Safety section for uncommon and serious reactions.
FDA category X. Indicated for pregnancy termination; contraindicated when continuing pregnancy is desired. After failed medical abortion with continued pregnancy — increased teratogenicity risk (Möbius syndrome from misoprostol); informed decision-making is offered.
Transfers into milk in small amounts. After a single dose, no feeding interruption is needed; with repeat dosing, skip feeds for 12 hours.
Mifepristone is contraindicated in: Suspected or confirmed ectopic pregnancy; Intrauterine device in place (remove first); Chronic adrenal insufficiency; Long-term corticosteroid therapy; Bleeding disorders, anticoagulant therapy. Full list in the Safety section.
FDA boxed warning: serious and sometimes fatal infections and bleeding after medical abortion. Patients must have access to emergency medical care for several days after misoprostol. Symptoms of serious complications require urgent hospital evaluation.