A comparative pharmacological study of trazodone, etoperidone and 1-(m-chlorophenyl)piperazine.

Since 1-(m-chlorophenyl)piperazine (mCPP) is a metabolite of trazodone (TRZ) and etoperidone (ETO), two atypical antidepressants, a pharmacological study was undertaken to establish the possible contribution of mCPP to the effects of the parent compounds. Behavioral effects of mCPP in rats consist in head shakes and other signs of serotoninergic stimulation; subtoxic doses also produce clonic convulsions and prostration. TRZ and ETO produce sedation and signs of alpha-adrenergic blockade; subtoxic doses produce tremors, clonic convulsions and prostration. Peripheral effects of norepinephrine (NE) and serotonin (5-HT) in rats are potentiated by mCPP and inhibited by TRZ and ETO. 5-hydroxytriptophan (5-HTP)-induced head twitches in mice are inhibited by TRZ and ETO and unaffected by mCPP. At similar doses mCPP, TRZ and ETO inhibit some nociceptive responses in rats and mice.