In vitro metabolism studies on mephedrone and analysis of forensic cases. Issue 6 (9th May 2012) - Pedersen, Anders Just
Abstract The stimulant designer drug mephedrone is a derivative of cathinone – a monoamine alkaloid found in khat – and its effect resembles that of 3, 4‐Methylenedioxymethamphetamine (MDMA). Abuse of mephedrone has been documented since 2007; it was originally a 'legal high' drug, but it has now been banned in most Western countries. Using cDNA‐expressed CYP enzymes and human liver microsomal preparations, we found that cytochrome P450 2D6 (CYP2D6) was the main responsible enzyme for the in vitro Phase I metabolism of mephedrone, with some minor contribution from other NAPDH‐dependent enzymes. Hydroxytolyl‐mephedrone and nor‐mephedrone were formed in vitro, and the former was purified and identified by nuclear magnetic resonance (NMR). In four forensic traffic cases where mephedrone was detected, we identified hydroxytolyl‐mephedrone and nor‐mephedrone again; as well as 4‐carboxy‐dihydro‐mephedrone, which has been previously described; and two new metabolites: dihydro‐mephedrone and 4‐carboxy‐mephedrone. Fragmentation patterns for all detected compounds were determined by a UPLC‐QTOF/MSE system, and a fragmentation pathway via a conjugated indole structure was proposed for most of the metabolites. Blood concentrations in the forensic traffic cases ranged from 1 to 51 µg/kg for mephedrone, and from not detected to 9 µg/kg for hydroxytolyl‐mephedrone. In one case, urine concentrations were also determined to be 700 µg/kg for mephedrone and 190 µg/kg for hydroxytolyl‐mephedrone. All compounds were detected or quantified with an ultra performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS) system and an ultra performance liquid chromatography‐time of flight/mass spectrometry (UPLC‐TOF/MS) system. Copyright © 2012 John Wiley & Sons, Ltd.