Abstract

In the current study, the metabolism of two examples of Novel Psychoactive Substances
(NPS), mephedrone and methoxetamine (MXE), were studied in vitro using pig liver
microsomes. Microsomes were prepared by a conventional ultracentrifugation method and
incubated with the drugs of interest for 3 hours, under optimised conditions. Subsequently,
the samples were investigated using liquid chromatography mass spectrometry detection
(LC/MS), where a qualitative analytical method has been successfully developed for the
detection of mephedrone, MXE and their metabolites. The analysis showed successful in
vitro metabolism and hence microsomes preparation, demonstrated by the production of two
known mephedrone metabolites, that have been previously reported in urine, namely
hydroxytoly-mephedrone and nor-dihydro mephedrone. For MXE, two first-time reported
metabolites are presented, produced by the O-demethylation and the reduction of the ketone
moiety to the corresponding alcohol, respectively and a mechanism proposed