Pregnancy interruption using mifepristone (RU-486). A new choice for women in the USA

Abstract

Mifepristone (RU-486) has recently been granted approval from the Food and Drug Administration for the early termination of pregnancy. Availability is anticipated during 1997. This article describes the pharmacologic function of mifepristone and discusses its potential clinical use in the United States, including its safety, efficacy, and possible complications.

PIP: The US Food and Drug Administration's recent approval of medical abortion involving use of RU-486, in combination with misoprostol, will provide US women with a new option that offers more privacy and greater accessibility than surgical abortion. When introduced before 8 weeks of gestation, RU-486 acts as a progesterone antagonist, competitively binding with the progesterone receptor and blocking the effect of natural progesterone. Although RU-486 alone is only 64-85% successful in expelling a pregnancy, addition of a prostaglandin analogue increases this rate to 95-99%. Potential complications of medical abortion include incomplete abortion and vaginal bleeding. The cost of an RU-486-induced abortion is expected to be comparable to that of surgical abortion (US $300). The choice of surgical versus medical abortion should be based on consideration of factors such as gestational age, the greater time and clinic visits required for RU-486 abortion, whether women prefer an active or passive role in the termination, and women's comfort level with exposure to the products of conception. Medical abortion should be denied to those with ongoing miscarriage, ectopic pregnancy, allergy to prostaglandins, cardiac conditions, heavy smoking, and age over 35 years. In 1992, the American College of Nurse-Midwives rescinded its ban on nurse-midwives performing pregnancy terminations, an important step given the shortage of abortion providers in the US. Surveys conducted among both nurse-midwives and physicians have revealed a greater willingness to provide medical than surgical abortions.