areas under the curve, and outcomes. What we now appear to know is that the 600-mg dose of mifepristone that we have been using appears far in excess of what is actually required, as you heard from Dr. Bygdeman this morning (see Appendix B5).
Does the dose make a difference? The pharmacology is very, very difficult. We don't see a linear relationship between dose and serum levels. Likewise, we don't see a linear relationship between dose and response. Nonetheless, it has been shown that the regimen does make a difference, and I will share with you our experience in Los Angeles.
Our experience using 13 different regimens (nearly all with mifepristone alone) can be divided into three broad categories: a single 600-mg dose, divided doses for a week, and all other regimens. Using regression analysis, we found three factors predictive of success for abortion: (1) body mass index, (2) initial beta human chorionic gonadotropin level, and (3) the regimen. The seven-day regimen was about twice as likely to result in failure as the other regimens and about six times as likely to fail as the single 600-mg dose. Each of these differences was highly statistically significant.
There is no free lunch in medicine, and we pay a price for everything we do. What should be the role of the prostaglandins with RU 486? After publication of the pivotal paper of Drs. Bygdeman and Swahn in 1985, the routine use of prostaglandins with RU 486 became common. We know that most of the noxious side effects and, indeed, the serious morbidity and mortality related to this regimen, result from the prostaglandins and not the RU 486—an example of the tail wagging the dog. The same week that a woman died in France with the RU 486 and prostaglandin regimen, we had a maternal death in Los Angeles of a 37-year-old woman who received a single, vaginal E2 suppository for abortion.
Since the prostaglandins cause most of the noxious side effects, the question we must ask ourselves is whether increasing the efficacy from the 80 to 90 percent range to the 90 to 100 percent range is worth the inconvenience, expense, and morbidity involved.
An important point that we heard raised this morning is that RU 486 may be most useful for augmenting second-trimester abortions. This has not received much attention in the United States. Premedication 36 to 48 hours before beginning an induction abortion cuts the time in half, and the important advantage here is that this now makes induction abortion