Search for new chemical entities as menses inducing agents

In continuation of an ongoing program on developing nonsteroidal pregnancy interceptives to be used as a menses regulating agent, a new class of compo unds belonging to 3-substituted amino-1-aryl-6-hydroxy-hex-2-ene-1-ones ser ies has been investigated for pregnancy interceptive activity in the hamste r and rat. The compounds were administered (subcutaneous) on days 4-8 (hams ter) and 5-9 (rat) post coitum (PC). The animals were laparotomized on days 12 (hamster) and 16 (rat) PC. To derive percent efficacy, the total number of implantation was divided by the number of normal and resorbed implantat ions. Among the 14 compounds evaluated, three were found to intercept pregn ancy by 100%. Another compound was active by 75%, whereas the rest were ina ctive. None of the active compounds were, however, active in rat with this schedule. Results indicate that the observed species- and schedule-specific activity owes its origins to differences in the implantation physiology an d early post-implantation development between the two species. The study, n evertheless, offers an insight to the new class of compounds for this activ ity. (C) 2001 Elsevier Science Inc. All rights reserved.