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

Intraperitoneal injection of alpha-difluoromethylornithine (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 day 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.