"Piperazines have been described as ‘failed pharmaceuticals’, as some had been evaluated as potential therapeutic agents by pharmaceutical companies but never brought to the market.55 While the best known piperazine that has been used as a new psychoactive substance is 1-benzylpiperazine (BZP), during the last decade other compounds such as 1-(3-chlorophenyl) piperazine (mCPP), 1-(3-trifluoromethylphenyl) piperazine (TFMPP) and, to a lesser extent, 1-Benzyl-4-methyl-piperazine (MBZP) and 1-(4-Fluorophenyl)piperazine (pFPP) have been identified on the market.56
"BZP was initially developed as a potential antidepressant drug, but was found to have similar properties to amphetamine and therefore liable to abuse. In the 1980s, it was used in Hungary to manufacture piberaline, a substance marketed as an antidepressant, but later withdrawn.57 In the late 1990s, BZP emerged in New Zealand as a ‘legal alternative’ for MDMA and methamphetamine.58 In Europe, its use was first reported in Sweden in 1999, but it only became widespread as a NPS from 2004 onwards until controls over the substance were introduced in 2008, in the European Union.59
"MCPP, reportedly more widespread than BZP in some regions of the world,60 was developed during the late 1970s and is used as an intermediate in the manufacture of several antidepressants, e.g. trazodone and nefazodone.61 TFMPP is almost always seen in combination with BZP to produce the entactogenic62 effects of MDMA.63
"Neither BZP nor any other piperazines are under international control, although several (BZP, TFMPP, mCPP, MDBP) were pre-reviewed by the WHO Expert Committee on Drug Dependence in 2012. Several countries have introduced national control measures over piperazines."


UN Office on Drugs and Crime, "The Challenge of New Psychoactive Substances: A Report from the Global SMART Programme" (Vienna, Austria: UNODC Laboratory and Scientific Section, March 2013), pp. 11-12.