The market of new psychoactive substances (NPS) is characterized by a high turnover and thus provides several challenges for analytical toxicology. The analysis of urine samples often requires detailed knowledge about metabolism given that parent compounds may either be present only in small amounts or may not even be excreted. Hence, knowledge of the metabolism of NPS is a prerequisite for the development of reliable analytical methods. The main aim of this work was to elucidate for the first time the pooled human liver S9 fraction metabolism of the nine d-lysergic acid diethylamide (LSD) derivatives 1-acetyl-LSD (ALD-52), 1-propionyl-LSD (1P-LSD), 1-butyryl-LSD (1B-LSD), N 6-ethyl-nor-LSD (ETH-LAD), 1-propionyl-N 6-ethyl-nor-LSD (1P-ETH-LAD), N 6-allyl-nor-LSD (AL-LAD), N-ethyl-Ncyclopropyl lysergamide (ECPLA), (2'S,4'S)-lysergic acid 2,4-dimethylazetidide (LSZ), and lysergic acid morpholide (LSM-775) by means of liquid chromatography coupled to high resolution tandem mass spectrometry. Identification of the monooxygenase enzymes involved in the initial metabolic steps was performed using recombinant human enzymes and their contribution confirmed by inhibition experiments. Overall, N-dealkylation, hydroxylation, as well as combinations of these steps predominantly catalyzed by CYP1A2 and CYP3A4 were found. For ALD-52, 1P-LSD, and 1B-LSD deacylation to LSD was observed. The obtained mass spectral data of all metabolites is essential for reliable analytical detection particularly in urinalysis and for differentiation of the LSD-like compounds as biotransformations also led to structurally identical metabolites. However, in urine of rats after the administration of expected recreational doses and using standard urine screening approaches, parent drugs or metabolites could not be detected.

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New psychoactive substances (NPS) are an important issue in clinical/forensic toxicology. 7'N-5F-ADB, a synthetic cannabinoid derived from 5F-ADB, appeared recently on the market. Up to now, no data about its mass spectral fragmentation pattern, metabolism, and thus suitable targets for toxicological urine screenings have been available. Therefore, the aim of this study was to elucidate the metabolic fate of 7'N-5F-ADB in rat, human, and pooled human S9 (pS9). The main human urinary excretion products, which can be used as targets for toxicological screening procedures, were identified by Orbitrap (OT)-based liquid chromatography-high resolution-tandem mass spectrometry (LC-HRMS/MS). In addition, possible differentiation of 7'N-5F-ADB and 5F-ADB via LC-HRMS/MS was studied. Using the in vivo and in vitro models for metabolism studies, 36 metabolites were tentatively identified. 7'N-5F-ABD was extensively metabolized in rat and human with minor species differences observed. The unchanged parent compound could be found in human urine but metabolites were far more abundant. The most abundant ones were the hydrolyzed ester (M5), the hydrolyzed ester in combination with hydroxylation of the tertiary butyl part (M11), and the hydrolyzed ester in addition to glucuronidation (M30). Besides the parent compound, these metabolites should be used as targets for urine-based toxicological screening procedures. Two urine-paired human plasma samples contained mainly the parent compound (c = 205 μg/L, 157 μg/L) and, at a higher abundance, the compound after ester hydrolysis (M5). In pS9 incubations, the parent compound, M5, and M30 were detectable among others. Furthermore, a differentiation of both compounds was possible due to different retention times and fragmentation patterns.

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Desomorphine is an opioid misused as "crocodile", a cheaper alternative to heroin. It is a crude synthesis product homemade from codeine with toxic byproducts. The aim of the present work was to investigate the metabolic fate of desomorphine in vivo using rat urine and in vitro using pooled human liver microsomes and cytosol as well as human liver cell lines (HepG2 and HepaRG) by Orbitrap-based liquid chromatography-high resolution-tandem mass spectrometry or hydrophilic interaction liquid chromatography. According to the identified metabolites, the following metabolic steps could be proposed: N-demethylation, hydroxylation at various positions, N-oxidation, glucuronidation, and sulfation. The cytochrome P450 (CYP) initial activity screening revealed CYP3A4 to be the only CYP involved in all phase I steps. UDP-glucuronyltransferase (UGT) initial activity screening showed that UGT1A1, UGT1A8, UGT1A9, UGT1A10, UGT2B4, UGT2B7, UGT2B15, and UGT2B17 formed desomorphine glucuronide. Among the tested in vitro models, HepaRG cells were identified to be the most suitable tool for prediction of human hepatic phase I and II metabolism of drugs of abuse. Finally, desomorphine (crocodile) consumption should be detectable by all standard urine screening approaches mainly via the parent compound and/or its glucuronide assuming similar kinetics in rats and humans.

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In vitro and in vivo experiments are widely used for studying the metabolism of new psychoactive substances (NPS). The availability of such data is required for toxicological risk assessments and development of urine screening approaches. This study investigated the in vitro metabolism of the 5 pyrrolidinophenone-derived NPS alpha-pyrrolidinobutyrophenone (alpha-PBP), alpha-pyrrolidinopentiothiophenone (alpha-PVT), alpha-pyrrolidinohexanophenone (alpha-PHP), alpha-pyrrolidinoenanthophenone (alpha-PEP, PV8), and alpha-pyrrolidinooctanophenone (alpha-POP, PV9). First, they were incubated with pooled human liver microsomes (pHLM) or pooled human liver S9 fraction (pS9) for identification of the main phase I and II metabolites. All substances formed hydroxy metabolites and lactams. Longer alkyl chains resulted in keto group and carboxylic acid formation. Comparing these results with published data obtained using pHLM, primary human hepatocytes (PHH), and authentic human urine samples, PHH provided the most extensive metabolism. Second, enzyme kinetic studies showed that the initial metabolic steps were formed by cytochrome P450 isoforms (CYP) CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 resulting in pyrrolidine, thiophene or alkyl hydroxy metabolites depending on the length of the alkyl chain. The kinetic parameters indicated an increasing affinity of the CYP enzymes with increase of the length of the alkyl chain. These parameters were then used to calculate the contribution of a single CYP enzyme to the in vivo hepatic clearance. CYP2C19 and CYP2D6 were mainly involved in the case of alpha-PBP and CYP1A2, CYP2C9 and CYP2C19 in the case of alpha-PVT, alpha-PHP, alpha-PEP, and alpha-POP.