Postcoital antifertility activity of aminoalcohols.

Previously, postcoital antifertility effects of a number of aminoalcohols, including 2-(isopropylamino)-ethanol, have been demonstrated in rodents. In this experiment, we compared the antifertility activity of 2-(isopropylamino)-ethanol to the following analogs: hydroxyethylpiperidine, hydroxyethylpiridine, hydroxyethylpirrolidine, and hydroxyethylpirrolidone. Female rats were gavaged on Days 0 through 5 of gestation with 0.7 mmol/kg/d of these substances. Only 2-(isopropylamino)-ethanol and hydroxyethylpirrolidine showed a strong antifertility activity: females treated with 2-(isopropylamino)-ethanol had no signs of implantation, whereas those treated with hydroxyethylpirrolidine had 100% early resorptions. Treatments with these two substances during the periimplantation period (Days 4 and 5) produced 100% early resorptions. Histologic examination of the implantation sites showed signs of embryonic degeneration starting from Day 6.5 of gestation. The flushing of the uteri of females treated with 2-(isopropylamino)-ethanol on Days 0 through 3 post coitum showed 78% of the embryos at the stage of 1 to 3 blastomeres, whereas the embryos of females treated during the same period with hydroxyethylpirrolidine were normal blastocysts. Therefore, 2-(isopropylamino)-ethanol and hydroxyethylpirrolidine are able to kill embryos during the early implantation stages, whereas 2-(isopropylamino)-ethanol is also able to stop the development of preimplantation embryos.