ortho-Methylphenylpiperazine (also known as oMPP, oMePP, 1-(2-methylphenyl)piperazine, 2-MPP, and 2-MePP) is a psychoactive designer drug of the phenylpiperazine group. It acts as a serotoninâÂÂnorepinephrineâÂÂdopamine releasing agent (SNDRA), with EC<sub>50</sub> values for induction of monoamine release of 175 nM for serotonin, 39.1 nM for norepinephrine, and 296âÂÂ542 nM for dopamine. As such, it has about 4.5-fold preference for induction of norepinephrine release over serotonin, and about 7.6- to 13.9-fold preference for induction of norepinephrine release over dopamine.
The 2,3-methyl and 4-methyl analogues show diminished activity as dopamine releasing agents with respective EC<sub>50</sub> values of 1,207 nM and 9,523 nM. However, at the same time, induction of serotonin and norepinephrine release is retained and more balanced in the 2,3-methyl analogue, with respective EC<sub>50</sub> values of 26 nM and 56 nM.