Objective: To review the literature concerning the mechanism of action and pharmacodynamics of mifepristone (RU486), potential new uses of RU486, and its current use not only as an abortifacient but also as therapy for endometriosis, leiomyoma, breast cancer, and meningioma.
Data identification and selection: Studies that relate to RU486 were identified through a MEDLINE search.
Conclusion(s): RU486 is an 11 beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. The receptor binding is not followed by transcription of P-dependent genes. Mifepristone effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. In addition, it has been used in the treatment of leiomyomata, endometriosis, advanced breast cancer, and meningioma. It is a powerful tool to study the molecular action of P and in the future may be used as an estrogen-free contraceptive.
PIP: Through an online search of MEDLINE, the authors reviewed the literature on the development of mifepristone (RU-486); RU-486's mechanism of action, pharmacodynamics, and distribution; the physiologic action of RU-486; potential new uses for RU-486; and its current use as both an abortifacient and therapy for endometriosis, leiomyoma, breast cancer, and meningioma. RU-486 is an 11beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. Receptor binding is not followed by the transcription of P-dependent genes. RU-486 effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. It has also been used to treat leiomyomata, endometriosis, advanced breast cancer, and meningioma. The following therapeutic uses of RU-486 are discussed: the termination of early pregnancy, treatment with RU-486 in combination with prostaglandins, the termination of second-trimester pregnancy, cervical ripening, labor induction, postcoital contraception, uterine leiomyomata, endometriosis, breast cancer, and meningioma.