Determination of 3-MeO-PCP in human blood and urine in a fatal intoxication case, with a specific focus on metabolites identification.
Forensic sciences research – January 01, 2021
Source: PubMed
Summary
A fatal 3-MeO-PCP intoxication case revealed a blood concentration of 3525 ng/mL, surpassing the previously reported fatal range (50-3200 ng/mL). This new psychoactive substance presents significant challenges for forensic toxicology. For the first time, its metabolites were thoroughly investigated in blood, alongside urine analysis. While several metabolites were identified, including two novel ones in both matrices, their low ratios to the parent drug suggest they may not extend the detection window critical for forensic sciences.
Abstract
3-Methoxyphencyclidine (3-MeO-PCP) is a new psychoactive substance that belongs to the phencyclidines family, first identified in Europe in 2012. This drug presents a stronger binding to N-methyl-D-aspartate (NMDA) receptors when compared to phencyclidine, which results in more potent effects, even at low concentrations. Very few articles have been published regarding 3-MeO-PCP in forensic toxicology. In this paper, the authors present a fatal 3-MeO-PCP intoxication case. In addition to the detection of the parent drug, metabolites were investigated in urine and, for the first time in the scientific literature, in blood. 3-MeO-PCP and its metabolites were quantitated by liquid chromatography-tandem mass spectrometry system (LC-MS/MS). Identification was confirmed by liquid chromatography-high resolution mass spectrometry (LC-HRMS). 3-MeO-PCP tested positive in femoral blood (3 525 ng/mL) and urine (7 384 ng/mL). The femoral blood concentration was higher than the fatal concentrations range already reported in the literature (from 50 to 3 200 ng/mL). 3-MeO-PCP metabolites, including O-demethyl-3-MeO-PCP, piperidine-OH-3-MeO-PCP, O-demethyl-piperidine-di-OH-3-MeO-PCP and piperidine-di-OH-3-MeO-PCP, were detected in blood. In addition, two new metabolites, O-demethyl-piperidine-OH-3-MeO-PCP and O-demethyl-cyclohexyl-OH, were identified in both blood and urine. Unfortunately, due to the lack of reference material on the market, it was not possible to measure the concentration of these metabolites. However, the ratios between the metabolites and the parent drug were useful to estimate their analytical response and prevalence. At this time, considering the low ratios (<1) between metabolites and parent drug, metabolites testing does not seem useful to increase the detection window of the drug.