Synthesis and pharmacological evaluation of carbamic acid 1-phenyl-3-(4-phenyl-piperazine-1-yl)-propyl ester derivatives as new analgesic agents.

A series of carbamic acid 1-phenyl-3-(4-phenyl-piperazine-1-yl)-propyl ester derivatives were synthesized through discovery strategies for balancing target-based in vitro screening and phenotypic in vivo screening. All the newly synthesized compounds were screened for their analgesic activities and compared with standard drug morphine. Among them, compound 44r, a potent analgesic agent that has favorable pharmacokinetic properties in rats and most importantly, has a wide safety margin. We demonstrated with in vitro and in vivo functional assays that its analgesic activity might be through 5-HT(2A) antagonism to some extent. Hence, it is concluded that there is ample scope for further study in developing compound 44r as a good lead candidate for an analgesic agent.