抄録
For the purpose of increasing the analgesic activity of N-[1-methyl-2-(4-phenethyl-piperazino) ethyl] propionanilide (I), several substituent groups were introduced into both benzene rings of I. 1-[2-Methyl-2-(N-propionyl-p-or m-substituted-phenylamino) ethyl]-4-phenethylpiperazines (VIa-f, h) and 1-[2-methyl-2-(N-propionyl-p-methoxyphenylamino) ethyl]-4-(p-substituted-phenethyl) piperazines (XIIa-e) were prepared by substitution at the p-or m-position of the aniline moiety, and by substitution at the p-position of the phenethyl moiety, respectively. Potent activity (92-100% inhibition of writhing at 30mg/kg, s.c.) could be achieved by introducing alkoxyl groups into the benzene ring of the aniline moiety. Among such compounds, 1-[2-methyl-2-(N-propionyl-p-methoxyphenylamino) ethyl]-4-phenethylpiperazine (VIa) showed the highest activity (ED50 : 1.64mg/kg, s.c.). On the other hand, introduction of several substituents into the benzene ring of the phenethyl moiety resulted in low analgesic activities (2-58% inhibition of writhing at 30mg/kg, s.c.).
