Title: Comparative effectiveness of three antiprogestins alone and in combination with anordiol in terminating pregnancy in the rat.

POPLINE Document Number: 120526

Author(s):

Dao B
Vanage G
Li XJ
Bardin CW
Koide SS

Source citation:

CONTRACEPTION, 1997 Jan;55(1):35-40.

Abstract:

The pregnancy termination potency of varying doses of mifepristone, onapristone, and ORG 3806--alone and in combination with the estrogenic/antiestrogenic compound anordiol--was evaluated in adult rats. The antiprogestins and anordiol alone were administered to pregnant female rats on days 7, 8, and 9 of pregnancy and the presence or absence of embryos in utero was determined on day 16. ORG 31806 at a dose of 2 mg/kg/day, mifepristone at 4 mg/kg/day, and onapristone at 8 mg/kg/day terminated pregnancy in 100% of animals; 5 mg/kg/day of anordiol was required. Anordiol acted synergistically with all three antiprogestins. Antiprogestin doses that were either partially effective or ineffective became 100% effective when administered with a noneffective dose of anordiol. The combination of ORG 31806 (1 mg/kg/day) and anordiol (0.31 mg/kg/day) had the most potent pregnancy termination activity. The administration of antiprogestins in combination with anordiol at doses that effectively terminate pregnancy was associated with a significant, persistent reduction in serum progesterone, but no change in serum estradiol levels. The effectiveness of ORG 31806 and anordiol in terminating pregnancy should be evaluated in a non-human primate model to determine its potential clinical use.

Keywords:

Research Report
Comparative Studies
Abortion
Animals, Laboratory
RU-486
Studies
Research Methodology
Fertility Control, Postconception
Family Planning
Clinical Research
Hormone Antagonists
Hormones
Endocrine System
Physiology
Biology