Fong MH, Garattini S, Caccia S. 1-m-Chlorophenylpiperazine is an active metabolite common to the psychotropic drugs trazodone, etoperidone and mepiprazole. J Pharm Pharmacol. 1982 Oct;34(10):674–5. doi: 10.1111/j.2042-7158.1982.tb04701.x. PMID: 6128394.