PIPERAZINE DERIVATIVE, PROCESS FOR PREPARATION THEREOF AND ANALGESIC COMPOSITION CONTAINING THE SAME

摘要

An analgesic composition containing as active ingredient a piperazine derivative represented by the general formula (1) < IMG > (1) wherein R1 represents a cyclopropylmethyl group, an isopropyl group or an allyl group and R2 represents a phenyl group having as substituent a halogen atom or a trifluoromethyl group.