Early termination of pregnancy with mifepristone (RU 486) and the orally active prostaglandin misoprostol.

Background and Methods. The combination of mifepristone (RU 486) and a prostaglandin analogue given either intramuscularly or intravaginally is effective in terminating early pregnancy, but the prostaglandin component of the regimen is cumbersome to administer and has side effects. We conducted two studies to determine the efficacy of 600 mg of mifepristone followed by a small dose of misoprostol, an orally active prostaglandin E 1 analogue, for the same purpose. In the first study, 505 women who had had amenorrhea for less than 50 days received 400 μg of misoprostol 48 hours after receiving mifepristone, if the pregnancy was not terminated within that period