Pretreatment with mifepristone (RU 486) reduces interval between prostaglandin administration and expulsion in second trimester abortion

Br J Obstet Gynaecol. 1990 Jan;97(1):41-5. doi: 10.1111/j.1471-0528.1990.tb01714.x.


The effect of pretreatment with mifepristone on prostaglandin-induced abortion was investigated in a double-blind randomized trial involving 100 women in the second trimester of pregnancy. The women were randomly allocated to receive either 600 mg oral mifepristone or placebo tablets 36 h before the administration of gemeprost pessaries. The median interval between administration of prostaglandin and abortion was significantly shorter in the mifepristone group (6.8 h) compared with the placebo group (15.8 h). The women pretreated with mifepristone required significantly fewer gemeprost pessaries to induce abortion and experienced significantly less pain than the women who had received placebo.

PIP: The use of prostaglandin analogues such as gemeprost has greatly improved the abortion rate in 2nd-trimester pregnancy; nonetheless, about 20% of women fail to abort after 24 hours of treatment with this method. RU-486, sensitizes the pregnant uterus to exogenous prostaglandins and has been shown in preliminary, uncontrolled studies to reduce the interval between extra-amniotic prostaglandin (PG) E2 instillation and expulsion as well as to reduce the amount of PGE2 required. The effect of pretreatment with RU-486 on prostaglandin- induced abortion was further evaluated in a double-blind, randomized study of 100 women in the 2nd trimester of pregnancy (12-18 weeks gestation). Study participants received 3 tablets of either a placebo or 200 mg of RU-486. 36 hours later, a 1 mg gemeprost pessary was inserted into the vagina and this treatment was repeated every 3 hours until either abortion occurred or 5 pessaries had been administered. The median interval to abortion after pessary insertion was significantly lower in the RU-485 pretreatment group (6.8 hours) than in the placebo group (15.8 hours). Moreover, women who received RU-486 required significantly fewer gemeprost pessaries (median of 3) than controls (median of 5); the former women also required significantly less analgesia. 94% of women in the RU-486 group compared to 80% of controls aborted during the 1st 24 hours after treatment. It is concluded that RU-486 pretreatment in gemeprost-induced 2nd-trimester abortion represents a major improvement in terms of safety and effectiveness.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Abortifacient Agents / administration & dosage*
  • Abortifacient Agents, Nonsteroidal / administration & dosage*
  • Abortion, Induced*
  • Adult
  • Alprostadil / administration & dosage
  • Alprostadil / analogs & derivatives*
  • Double-Blind Method
  • Female
  • Humans
  • Mifepristone / administration & dosage*
  • Mifepristone / adverse effects
  • Pregnancy
  • Pregnancy Trimester, Second
  • Randomized Controlled Trials as Topic
  • Time Factors


  • Abortifacient Agents
  • Abortifacient Agents, Nonsteroidal
  • Mifepristone
  • gemeprost
  • Alprostadil