Mifepristone

Products

Mifepristone is commercially available in tablet form (Mifegyne). It was first approved in 1988 and in many countries in 1999. Mifepristone was discovered in the 1980s at Roussel-Uclaf (RU) during the development of antiglucocorticoid agents and is therefore also known as RU 486.

Structure and properties

Mifepristone (C29H35NO2, Mr = 429.6 g/mol) is a synthetic derivative of the progestogen norethisterone with a steroidal structure.

Effects

Mifepristone (ATC G03XB01) has antigestagenic properties. It is a competitive antagonist of the pregnancy hormone progesterone at progesterone receptors. This results in termination of pregnancy. Mifepristone further has antiglucocorticoid and mild antiandrogenic effects. The half-life ranges from 20 to 40 hours.

Indications

For drug termination of intrauterine pregnancy in sequential use with a prostaglandin analog up to an amenorrhea duration of 49 days. Other indications and indications for use exist.

Dosage

According to the SmPC. Drug abortion: the tablets are taken as a single dose. Thirty-six to 48 hours later, the prostaglandin misoprostol is administered perorally. It is used in a clinic or treatment center under medical supervision.

Contraindications

  • Hypersensitivity
  • Chronic adrenocortical insufficiency
  • Severe, uncontrollable asthma
  • Inherited porphyria
  • Pregnancy that has not been confirmed by ultrasound examination
  • Duration of pregnancy over 49 days
  • Suspicion of extrauterine pregnancy
  • Contraindications of the applied prostaglandin.

Full precautions can be found in the drug label.

Interactions

Mifepristone is a substrate of CYP3A4 and corresponding drug-drug interactions are possible. NSAIDs should not be administered concomitantly because they may reduce its efficacy. Mifepristone may further reduce the effects of glucocorticoids because it has antiglucocorticoid properties.

Adverse effects

The most common possible adverse effects include vaginal bleeding, uterine contractions, cramping, infection, diarrhea, nausea, and vomiting.

Controversy

Mifepristone is controversial among abortion opponents because they oppose medication abortion on ethical, religious, or other grounds.