Mifepristone (RU-486): overview, properties, uses and history

Characteristics and pharmacology

Mifepristone binds to progesterone receptors and prevents the hormone from maintaining the uterine lining, which allows detachment of the embryo. It also increases uterine contractility indirectly when followed by a prostaglandin, and interferes with decidual support. In addition, it has activity at glucocorticoid receptors, which underlies some of its non-reproductive uses. For drug information and prescribing notes consult clinical resources.

History and development

The substance was discovered in the late 1970s and developed into a clinical drug in the following decade. After initial trials and regulatory review, it became the subject of political, ethical and legal debate because of its role in abortion care. Production and approval timelines have varied by country, and access remains governed by national law and health policy. For historical context see origin and discovery.

Clinical uses

• Medical abortion in early pregnancy, typically used together with a prostaglandin analogue to complete the process.
• Management of miscarriage and incomplete abortion in some clinical protocols.
• Off-label or approved uses in some jurisdictions for conditions related to cortisol excess, reflecting its antiglucocorticoid activity.
• It has been studied in contraceptive and emergency contraception roles at different dosages and regimens.

Regimens, timing, and effectiveness depend on local guidelines and clinical practice; see further guidance at treatment protocols and clinical guidance.

Safety, side effects and legal context

Common adverse effects include bleeding and uterine cramping; nausea, weakness and fever can also occur. Serious complications are uncommon but can include heavy bleeding and infection, and patients are usually advised to have access to follow-up care. Legal status, availability and required medical supervision vary widely by country and are subject to regulatory change. For patient information consult trusted sources and local health authorities.

Distinguishing mifepristone from other reproductive drugs is helpful: it is not a contraceptive pill in the routine sense but can serve in specific emergency regimens; it is pharmacologically distinct from agents that act solely as prostaglandins. For research and regulatory details see chemical class, mechanism, and clinical references.