α-difluoromethylornithine as a postcoitally effective antifertility agent in female rats

Intraperitoneal injection of α-difluoromethyl-ornithine (DFMO) at a dose of 200 mg/kg, twice a day, during days 4–7 of pregnancy caused inhibition of embryogenesis in rats. These animals did not deliver any pups at term. However, there was no effect of DFMO on pregnant rats following treatment during days 1–3 of pregnancy. It was observed that DFMO completely abolished ornithine decarboxylase levels in the pregnant uterus. The action of DFMO appears to be due to the inhibition of putrescine and polyamines during a critical period of early embryo development. We suggest that this drug may act as a postcoitally effective antifertility agent in females.