RU 486: an overview of mifepristone and its potential applications.

RU-486's primary use as an abortifacient stirs controversy in the US. Changes in US policy have opened the door for RU-486 to be made available for research. The Population Council plans on conducting a multicenter clinical trial of RU-486 involving at least 2000 women. This is the first step to obtaining possible approval from the Food and Drug Administration. RU-486 alone has an effectiveness rate of inducing abortion between 80 and 90%. When taken 36 to 48 hours before a prostaglandin (PG) analogue, the rate climbs to about 95%. Possible side effects of RU-486 and the analogue are bleeding, abdominal pain, and cardiovascular problems (rare). More than 100,000 women in France have undergone the RU-486/PG analogue regimen. RU-486 also has contraceptive qualities. If taken every day during the week before ovulation, it prevents ovulation. 12 days of RU-486 administration followed by 10 days of administration of a synthetic progestin also suppresses ovulation. Taking RU-486 during the last 10 to 12 days of the menstrual cycle alters the endometrium, thereby preventing implantation. A single dose of RU-486 during the late luteal phase is about 80% effective at bringing on menses. The aforementioned effects of Ru-486 demonstrate that it may be an effective postcoital contraceptive. Besides, RU-486 has fewer side effects than other postcoital contraceptive regimens. Further, RU-486 softens and dilates the cervix, thus it can be used to induce labor and ease delivery. Evidence suggests that RU-486 may be used to treat hormone-dependent breast tumors, Cushing's syndrome, meningiomas, and endometriosis.