. "B6. Uses of Antiprogestins After 63 Days of Amenorrhea." Clinical Applications of Mifepristone (RU486) and Other Antiprogestins: Assessing the Science and Recommending a Research Agenda. Washington, DC: The National Academies Press, 1993.
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Clinical Applications of Mifepristone (RU 486) and other Antiprogestins: Assessing the Science and Recommending a Research Agenda
RU 486 FOR SECOND-TERM PREGNANCY TERMINATION
Second-term pregnancy termination can be achieved through either surgical means (dilatation and evacuation) or medical treatment (with local or systemic prostaglandins). Prostaglandins, although efficient, induce many side effects. These side effects can sometimes be severe, hence the importance of using doses as low as possible. Previous studies with RU 486, including studies of first-term pregnancy termination, indicate that RU 486 treatment sensitizes the myometrium to the action of prostaglandins, allowing a decrease in the amount of prostaglandin necessary to induce expulsion. This observation led to several clinical trials in which the effect of RU 486 treatment prior to PG administration was evaluated as a means to allow a decrease in PG doses and to accelerate expulsion in second-term pregnancy termination. The results of the trials are summarized in Table B6.1.
These studies indicate that treatment with RU 486 prior to PGs allows a significant decrease of the PG doses and significantly shortens the induction to abortion interval. This finding is of great clinical value for the comfort of patients. In one study (Roussel-Uclaf, data on file), the duration of hospitalization was shortened by one day in the group given RU 486. In another study (Thong and Baird, 1992), which compared RU 486 and laminaria tent (Dilapan) in gemeprost-induced abortion, RU 486 resulted in a significantly shorter induction-abortion interval than Dilapan.
RU 486 FOR INTRAUTERINE FETAL DEATH (IUFD)
After a pilot study suggested that the compound alone seemed efficient to induce expulsion of the dead fetus, a placebo-controlled study was undertaken to evaluate the efficacy of RU 486, given as 600 mg for two consecutive days, in this condition. Results of this study, published elsewhere (Cabrol et al., 1990), are summarized in Table B6.2.
These results show that RU 486 alone was able to induce labor in patients with IUFD and that expulsion took place significantly earlier than in patients given a placebo.
CERVICAL RIPENING WITH RU 486 PRIOR TO SURGICAL ABORTION
Animal studies have demonstrated that RU 486 is able to mature the cervix, evidenced by an increase in cervical diameter and a decrease of cervical resistance to mechanical dilation (Stiemer and Elger, 1990; Cabrol et al., 1991). It has also been shown that RU 486 triggers the biochemical modifications that characterize the normal process of cervi-