Termination of Early Pregnancy by the Progesterone Antagonist RU 486 (Mifepristone)

Abstract

We studied the effects of the progesterone antagonist RU 486 in 100 women with early, unwanted pregnancy (within 10 days of the expected onset of the missed menstrual period). Thirty-four women received oral doses of 400 mg (in four days), 26 received 600 mg (in four days), and 40 received 800 mg (in two days). Uterine bleeding occurred in all patients within four days of the first dose and continued for 5 to 17 days. In 85 of the women, a dramatic decrease in the plasma chorionic gonadotropin level was observed on day 6, and an empty uterus was confirmed by ultrasonography on day 13. Hence, these women were considered to have had a complete abortion. Fifteen subjects had persistently elevated plasma chorionic gonadotropin levels on day 6 and were considered not to have responded to RU 486. They all had uterine evacuation, which was facilitated by a softening of the cervix. The percentage of women with complete abortion was similar in all dosage groups. Furthermore, plasma levels of immunoreactive RU 486 were similar in subjects with and without complete abortion. The only important side effect observed in the responders was prolonged uterine bleeding in 18 percent, but neither blood transfusion nor curettage was required. We conclude that RU 486 is an effective and safe method for termination of very early pregnancy but that it should be used only under close medical supervision.

Antioxidant: a new role for RU-486 and related compounds.

“…These compounds did not show any significant antioxidant effects even at 10-MM levels (Figs. 4 the other hand, tripled the lag phase. In contrast, clomiphene and NN'-dimethylaniline, nonsteroid compounds with diethyland dimethylamino groups, respectively, were effective in decreasing the oxidation of LDL (Fig.…”

“…In addition to its use in the termination of pregnancy (3,4), recent studies have suggested that RU-486 is effective in providing relief from pain associated with endometriosis (5), and induced a marked reduction in leiomyoma volume (6). Further-more, tumors that have hormone receptors, such as breast cancer and meningiomas, have been reported to respond clinically to RU-486 (7)(8)(9).…”

Effect of progesterone-carbachol derivative on perfusion pressure and coronary resistance in isolated rat heart: via activation of the M₂ muscarinic receptor

“…To characterize the molecular mechanism of this phenomenon we analyzed the reports of some investigations which indicate that progesterone induces its effect on blood pressure via activation of the progesterone receptor 22,23 . For this reason, we used mifepristone, a progesterone receptor blocker 14 to determine if the effects of progesterone-carbachol derivative on perfusion pressure were via the progesterone receptor. It is important to mention that interaction of progesterone-carbachol derivative with the progesterone -receptor may be a key requirement for the biological activ- progesterone-carbachol (10 -9 to 10 -4 mM) was administered (intracoronary boluses, 50 μL) and the corresponding effect on the perfusion pressure was evaluated in absence and presence of yohimbine (10 -6 mM).…”

In vivo evidence against the existence of antiprogestins disrupting receptor binding to DNA.

“…(i) They have been shown to have a great therapeutic potential: interruption of early pregnancy (1,2), postcoital contraception (3), triggering of labor (4), and treatment of hormone-dependent tumors (5)(6)(7). (ii) Antiprogestins have also been used as potent tools to decipher the molecular mechanisms of action of the hormone (8,9).…”