The dynamic changes of several reproductive hormones during termination of early pregnancy by RU486 in combination with PG-05 in Chinese women

8 pregnant women (below 49 days of amenorrhea) were administered 600 mg RU486 orally in a single dosage, and 1 mg PG-05 as a vaginal suppository 48 h afterwards. The plasma beta-hCG, progesterone, 17 beta-estradiol and PGFM (13,14-dihydro-15-keto-PGF2 alpha) were determined by RIAs throughout the treatment. In all 8 cases, beta-hCG and progesterone levels fell following the onset of bleeding, which happened in a mean time of 39 h after RU486 administration. In 7 women who experienced complete abortion, E2 dropped after 72 h and PGFM increased two-fold within 48 h. In comparison with these results of complete abortion, the concentrations of E2 in the woman experiencing incomplete abortion were much higher, while those of PGFM were much lower. The results suggest that the primary action site of RU486 is probably in the decidual tissue, because of the progesterone-antagonistic property of RU486, which in turn leads to the drop in beta-hCG, progesterone and E2. It also indicates that RU486 may facilitate the production of endogenous prostaglandins, which can be explained by the changes of decidual tissue induced by RU486.