Effects of anordrin and its analogue on antifertility.

Anordrin has been used as an effective postcoital contraceptive in China. The mechanism of anordrin and its analogue SIPPR-113 on antifertility has been studied. Anordrin and SIPPR-113 possessed estrogenicities and induced decrease in serum progesterone levels in rats. Their antiprogesterone activities might be mainly caused by their estrogenicities, which were the main but not the only contributors for the antifertility. The direct effects of anordrin and SIPPR-113 on human trophoblast cells were studied. A concentration of 50 micrograms/ml or 100 micrograms/ml of anordrin or SIPPR-113 could injure the human trophoblast cells in vitro. The uterine Pontamine blue reaction of mated rats was inhibited in those treated with anordrin or SIPPR-113 at the dose of 4 mg/kg. Anordrin, SIPPR-113 or AF-45 was given orally, intramuscularly and intravenously. The effects of drugs administered via the three routes were nearly the same. This study further demonstrated that anordrin was hydrolyzed to break its bond of dipropionate and was transformed into its parent steroid AF-45 to exert its antifertility effects in vivo. This study warrants that anordrin should been evaluated further.