1-(3-Chlorophenyl)-4-(2-phenylethyl)piperazine

1-(3-Chlorophenyl)-4-(2-phenylethyl)piperazine (3C-PEP) is a designer drug of the piperazine class of chemical substances. 3C-PEP is related to meta-cholorophenylpiperazine (mCPP) and phenethylamine that can be thought of as mCPP having a phenylethyl group attached to the nitrogen atom at its 4-position. It was first described in 1994 in a patent disclosing a series of piperazine compounds as sigma receptor ligands. Later, it was discovered to be a highly potent dopamine reuptake inhibitor.

Pharmacology
3C-PEP is one of the most potent dopamine transporter (DAT) ligand reported to date. It is highly selective for the dopamine transporter (dissociation constant K$i$ = 0.04 nM) with relatively low affinity for the closely related norepinephrine transporter (NET, K$i$ = 1107 nM ) and the serotonin transporter (SERT, K$i$ = 802 nM). In addition, the compound has lower (or no) affinity for D2-like receptor (K$i$ = 327 nM), serotonin 5-HT2 receptor (K$i$ = 53 nM), opioid receptor (K$i$ > 10000 nM), and the PCP/NMDA receptor (K$i$ > 10000 nM).

With a DAT dissociation constant K$i$ of 0.04 nM, 3C-PEP is one of the most potent dopamine transporter ligand described to date in the literature. In comparison, cocaine which is a prototypical DAT ligand and reuptake inhibitor has a dissociation constant K$i$ of 435 nm thus making 3C-PEP about 10,000 times more potent than cocaine as a dopamine transporter inhibitor in vitro.

United States
3C-PEP is not scheduled at the federal level in the United States,

Canada
3C-PEP is not scheduled under the Controlled Drugs and Substances Act.