Mifepristone

To review the efficacy and safety of mifepristone (with misoprostol) for the termination of early pregnancy.

A MEDLINE search (1966-October 2000) was conducted, and additional references listed in articles were included; unpublished data obtained from the manufacturer were used to identify data from the scientific literature. Studies evaluating mifepristone were considered for inclusion.

Human clinical studies in the English language were reviewed and evaluated. Clinical trials selected for detailed review were limited to those including the regimens of mifepristone and misoprostol, recently approved by the Food and Drug Administration for early pregnancy termination.

Mifepristone is an antiprogestin available for pregnancy termination in combination with a prostaglandin such as misoprostol. Mifepristone offers efficacy similar to, if not better than, other drugs used for pregnancy termination, but appears less efficacious overall than surgical termination of pregnancy. Mifepristone in combination with misoprostol commonly causes adverse effects such as abdominal pain and, less commonly, can cause serious adverse effects such as incomplete abortion; endometritis; and bleeding warranting transfusion, hospitalization, or surgery. Mifepristone is metabolized by the cytochrome P450 system. Thus, the potential for drug interactions with this agent exists, although this has not been well studied. Data are included from clinical trials evaluating the safety, tolerability, efficacy, and pharmacoeconomics of mifepristone combined with misoprostol for early pregnancy termination. Data comparing the use of these agents with surgical abortion and other drugs used for pregnancy termination are included where available.

Mifepristone in combination with misoprostol for the termination of early pregnancy (amenorrhea of < or = 49 d) is effective in 92-95% of women. Incomplete abortion requiring surgical abortion after the fact occurs in 3-5% of women, and pregnancy continues 1-2% of the time. Mifepristone with misoprostol treatment is not without significant risks, including hemorrhage, infection, and potential for long-term emotional consequences.