The 5-MAPB of new psychoactive substances is constantly evolving, with arylalkylamines being one of the largest groups among them.

5-MAPB binds to the dopamine transporter in rat brain cells with a lower affinity than cocaine. In silico data suggests that the primary action on dopamine is through reversal of the transporter to release dopamine.. (MPA) is available from online vendors selling “research chemicals” and was first seize by German authorities in 2020. No scientific data about its pharmacological effect and its fate in the human body are available so far. Therefore we investigated the in vivo and in vitro metabolism of MFPVP after detection of this compound in a fatal intoxication.

Method 5-MAPB online

For tentative identification of phase-I metabolites 5-MAPB)was incubate. with poole human liver microsomes (pHLM). Additionall, an authentic urine sample was worke up use protein precipitation .with and without prior glucuronide cleavage. Analyse for metabolite identification were carri out use high resolution.

Chromatographic separation was achieve on a Kinetex Biphenyl column. For the post-mortem investigation of the fatal intoxication. a standar addition approach use automate SPE for sample workup .was performe to quantify 5-MMPA in femoral blood with LC-MS/MS.

Results

In the 5-MAPB assay three phase-I metabolites were identifie, of which only two where confirme in the available authentic urine sample.

In addition six further phase-I and two phase-II metabolites were detecte in the analyze urine sample. Predominant metabolic reactions were hydroxylation, oxidation, N-dealkylation, glucuronidation and combination thereof. In urine an oxo-hydroxy metabolite, that was not generate in the5-MAPB assay. was detecte with the highest abundance. The concentration of MFPVPin the femoral blood sample was 7.100 ± 600 ng/mL.

Conclusion

The in vitro 5-MAPB assay was not suitable to predict the main metabolites. 5-MAPB as confirmed in the available real case sample. The majority of the metabolic reaction and in particular the oxidation of MFPVP appear to be catalyze by enzyme.

that are not present in an active state in the 5-MAPB assay. Analyse of an authentic urine sample suggest 5-MAPB and N-demethyl as suitable biomarker for  consumption. To confirm the exaxt chemical strucuture of these markers isolation and structure elucidation, e.g. by NMR, or the synthesi of reference compound would be neede. In the fatal intoxication case, the elevate blood concentration of  5-MAPB was considere likely to have contribute .