Liquid chromatography-quadrupole time-of-flight mass spectrometry for screening in vitro drug metabolites in humans: investigation on seven phenethylamine-based designer drugs

Improving wastewater-based epidemiology for new psychoactive substance surveillance by combining a high-throughput in vitro metabolism assay and LC-HRMS metabolite identification

One of the primary criteria for a suitable drug biomarker for wastewater-based epidemiology (WBE) is having a unique source representing human metabolism. For WBE studies, this means it is important to identify and monitor metabolites rather than parent drugs, to capture consumption of drugs and not fractions that could be directly disposed. In this study, a high-throughput workflow based on a human liver S9 fraction in vitro metabolism assay was developed to identify human transformation products of new chemicals, using α-pyrrolidino-2-phenylacetophenone (α-D2PV) as a case study. Analysis by liquid chromatography coupled to high resolution mass spectrometry identified four metabolites. Subsequently, a targeted liquid chromatography - tandem mass spectrometry method was developed for their analysis in wastewater samples collected from a music festival in Australia. The successful application of this workflow opens the door for future work to better understand the metabolism of chemicals and their detection and application for wastewater-based epidemiology.

Structural confirmation of position isomers 2-(2-methylaminoprolyl)benzofuran and 5-(2-methylaminopropyl)benzofuran: a combined mass spectrometric and computational study

RATIONALE

Phenylethylamines are one of the most common types of new psychoactive substances, following synthetic cannabinoids and synthetic cathinones. They are regulated in many countries because of their strong hallucinogenic effects, which can cause serious nerve damage. There is a wide variety of phenylethylamines, exhibiting rapid renewal and extremely similar structures, therefore accurate qualitative analysis of isomers is a difficult problem in current drug analysis.

METHODS

The dissociation pathways of the position isomers 2-(2-methylaminoprolyl)benzofuran (2-MAPB) and 5-(2-methylaminopropyl)benzofuran (5-MAPB) were investigated by gas chromatography-mass spectrometry and liquid chromatography coupled to high-resolution quadrupole Orbitrap MS. The dissociation patterns of the phenethylamine-based designer drugs 2-MAPB and 5-MAPB were explored and extended in this work based on MS combined with density functional theory studies.

RESULTS

For electron ionization mass spectrometry (EI-MS) analysis, the dissociation patterns of 2-MAPB were similar to those of 5-MAPB. For electrospray ionization mass spectrometry (ESI-MSn ) analysis, the hydrogen atom on amino group was facile to form a intramolecular hydrogen bond with the oxygen atom on the parent nucleus of benzofuran in the structure of 2-MAPB, leading to higher abundance of the product ion at m/z 58. However, there was a conjugated system between the positive charge formed by the cleavage of the 5-MAPB side chain and the benzofuran ring, enabling the 5-MAPB to generate a product ion at m/z 131. Computational study showed that energy barrier and spin density difference distribution jointly control the selective dissociation in EI-MS, while different types of orbital interaction induced by intramolecular hydrogen bond led to different dissociation results in ESI-MSn .

CONCLUSIONS

These different dissociation patterns could be used to distinguish 2-MAPB from 5-MAPB. This could assist forensic laboratories in the differentiation and characterization of potential isomers in these kinds of compounds, especially in mixtures.

Structural confirmation of synthetic cannabinoids in seized electronic cigarette oil: A combined mass spectrometric and computational study

RATIONALE

Synthetic cannabinoids are some of the most used and abused new psychoactive substances, because they can produce a stronger intense pleasure than natural cannabis. Most of the new synthetic cannabinoids are structurally similar to existing synthetic cannabinoids and can be obtained by modifying partial structures of the latter without changing their effects. Therefore, the derivatization rules and common fragmentation patterns of synthetic cannabinoids could be used for rapid screening and structural identification of them.

METHODS

The derivatization rules of synthetic cannabinoids are summarized, and the common fragmentation pattern of synthetic cannabinoids including three typical cleavage pathways was explored and extended in this work based on combined mass spectrometry (MS) and density functional theory studies. Five synthetic cannabinoids in electronic cigarette oil from a drug case were separated and characterized using gas chromatography with MS and liquid chromatography coupled to high-resolution quadrupole Orbitrap MS.

RESULTS

The structures of five synthetic cannabinoids in seized electronic cigarette oil were deduced from electron impact ion source (EI) MS and high-resolution electrospray ionization (ESI) MSⁿ data, along with the derivatization rules and common fragmentation pattern of synthetic cannabinoids. The proposed structures of these synthetic cannabinoids were further verified via reference substances. Computational study showed that selective cleavage of these compounds was mainly controlled by spin population in EI-MS, but a tunneling effect arose from proton transfer in ESI-MSⁿ detection, which has been rarely reported in previous works.

CONCLUSIONS

Our results showed that EI-MS was suitable for identifying synthetic cannabinoids with aromatic ketone structure, which could also be extended to adamantane linked group. Nevertheless, synthetic cannabinoids with carbamoyl linked group were better characterized by high-resolution ESI-MSⁿ compared to EI-MS. This study demonstrated a method with promising potential for rapid and reliable screening of synthetic cannabinoids in mixtures with enhanced detection throughput and operation simplicity.

In vitro biotransformation and evaluation of potential transformation products of chlorinated paraffins by high resolution accurate mass spectrometry

Chlorinated paraffins (CPs) are high production chemicals, which leads to their ubiquitous presence in the environment. To date, few studies have measured CPs in humans and typically at relatively low concentrations, despite indications that exposure may be high compared to various persistent organic pollutants. The aim of this study is to investigate the in vitro biotransformation of CPs by human liver fractions. We determined the changes of the CP concentrations after the enzymatic transformation with human liver microsomes using a two-tiered in vitro approach. CP concentrations decreased with human liver microsomes, with the decreases of 33-94% after incubating with different groups of enzymes for 2 h. The profiles of CP rapidly shifted after the incubation with human liver microsomes. In addition, the concentrations of CPs and the biotransformation products were tentatively measured using high-resolution mass spectrometric analysis, including very short CP (carbon chain length <10), alcohols, ketones, and carboxylic acids. C‒C bond cleavage is a potential transformation pathway for CPs, and ketones are potential products of CP biotransformation, especially for long-chain CPs (C_>17). The ketone products may be investigated as CP exposure biomarker in biomonitoring studies.

The Feasibility of Studying Metabolites in PICU Multi-Organ Dysfunction Syndrome Patients over an 8-Day Course Using an Untargeted Approach

Metabolites are generated from critical biological functions and metabolism. This pediatric study reviewed plasma metabolites in patients suffering from multi-organ dysfunction syndrome (MODS) in the pediatric intensive care unit (PICU) using an untargeted metabolomics approach. Patients meeting the criteria for MODS were screened for eligibility and consented (n = 24), and blood samples were collected at baseline, 72 h, and 8 days; control patients (n = 4) presented for routine sedation in an outpatient setting. A subset of MODS patients (n = 8) required additional support with veno-atrial extracorporeal membrane oxygenation (VA-ECMO) therapy. Metabolites from thawed blood plasma were determined from ion pairing reversed-phase liquid chromatography–mass spectrometry (LC-MS) analysis. Chromatographic peak alignment, identification, relative quantitation, and statistical and bioinformatics evaluation were performed using MAVEN and MetaboAnalyst 4.0. Metabolite analysis revealed 115 peaks per sample. From the partial least squares-discriminant analysis (PLS-DA) with variance of importance (VIP) scores above ≥2.0, 7 dynamic metabolites emerged over the three time points: tauro-chenodeoxycholic acid (TCDCA), hexose, p-hydroxybenzoate, hydroxyphenylacetic acid (HPLA), 2_3-dihydroxybenzoic acid, 2-keto-isovalerate, and deoxyribose phosphate. After Bonferroni adjustment for repeated measures, hexose and p-hydroxybenzoate were significant at one time point or more. Kendall’s tau-b test was used for internal validation of creatinine. Metabolites may be benign or significant in describing a patient’s pathophysiology and require operator interpretation.

Investigation of Biotransformation Products of p-Methoxymethylamphetamine and Dihydromephedrone in Wastewater by High-Resolution Mass Spectrometry

There is a paucity of information on biotransformation and stability of new psychoactive substances (NPS) in wastewater. Moreover, the fate of NPS and their transformation products (TPs) in wastewater treatment plants is not well understood. In this study, batch reactors seeded with activated sludge were set up to evaluate biotic, abiotic, and sorption losses of p-methoxymethylamphetamine (PMMA) and dihydromephedrone (DHM) and identify TPs formed during these processes. Detection and identification of all compounds was performed with target and suspect screening approaches using liquid chromatography quadrupole-time-of-flight mass spectrometry. Influent and effluent 24 h composite wastewater samples were collected from Athens from 2014 to 2020. High elimination rates were found for PMMA (80%) and DHM (97%) after a seven-day experiment and degradation appeared to be related to biological activity in the active bioreactor. Ten TPs were identified and the main reactions were O- and N-demethylation, oxidation, and hydroxylation. Some TPs were reported for the first time and some were confirmed by reference standards. Identification of some TPs was enhanced by the use of an in-house retention time prediction model. Mephedrone and some of its previously reported human metabolites were formed from DHM incubation. Retrospective analysis showed that PMMA was the most frequently detected compound.

Perspectives and challenges associated with the determination of new psychoactive substances in urine and wastewater - A tutorial

New psychoactive substances (NPS), often designed as (legal) substitutes to conventional illicit drugs, are constantly emerging in the drug market and being commercialized in different ways and forms. Their use continues to cause public health problems and is therefore of major concern in many countries. Monitoring NPS use, however, is arduous and different sources of information are required to get more insight of the prevalence and diffusion of NPS use. The determination of NPS in pooled urine and wastewater has shown great potential, adding a different and complementary light on this issue. However, it also presents analytical challenges and limitations that must be taken into account such as the complexity of the matrices, the high sensitivity and selectivity required in the analytical methods as a consequence of the low analyte concentrations as well as the rapid transience of NPS on the drug market creating a scenario with constantly moving analytical targets. Analytical investigation of NPS in pooled urine and wastewater is based on liquid chromatography hyphenated to mass spectrometry and can follow different strategies: target, suspect and non-target analysis. This work aims to discuss the advantages and disadvantages of the different data acquisition workflows and data exploration approaches in mass spectrometry, but also pays attention to new developments such as ion mobility and the use of in-silico prediction tools to improve the identification capabilities in high-complex samples. This tutorial gives an insight into this emerging topic of current concern, and describes the experience gathered within different collaborations and projects supported by key research articles and illustrative practical examples.

CYP450-Mediated metabolism of suvorexant and investigation of metabolites in forensic case specimens

Suvorexant (Belsomra®) is a sedative hypnotic that was approved for use in 2015. It has a novel mechanism of action and was the first dual orexin receptor antagonist (DORA) to be approved for the treatment of sleep disorders. Sedative hypnotics often feature prominently in forensic investigations such as impaired driving and drug-facilitated sexual assault (DFSA) cases. As such, suvorexant is a drug of interest and its identification in forensic toxicology investigations is of significance. However, limited studies have been published to date and the disposition or importance of its metabolites has been largely uninvestigated. In this report, we investigate the enzymes responsible for metabolism and explore the prevalence of metabolites in blood from a series of thirteen forensic investigations. Recombinant cytochrome P450 enzymes (rCYPs) were used to generate phase I metabolites for suvorexant in vitro, and metabolites were identified using liquid chromatography-quadrupole/time-of-flight-mass spectrometry (LC-Q/TOF-MS). Four rCYP isoenzymes (3A4, 2C19, 2D6, and 2C9) were found to contribute to suvorexant metabolism. The only metabolite identified in blood or plasma arose from hydroxylation of the benzyl triazole moiety (M9). This metabolite was identified in seventeen blood and plasma specimens from twelve medicolegal death investigations and one impaired driving investigation. In the absence of a commercially available reference material, the metabolite was confirmed using rCYP-generated in vitro controls using high resolution mass spectrometry.

Flexible high resolution-mass spectrometry approach for screening new psychoactive substances in urban wastewater

The number of new psychoactive substances (NPS) on the recreational drug market has increased rapidly in the last years, creating serious challenges for public health agencies and law enforcement authorities. Epidemiological surveys and forensic analyses to monitor the consumption of these substances face some limitations for investigating their use on a large scale in a shifting market. The aim of this work was to develop a comprehensive and flexible screening approach for assessing the presence of NPS in urban wastewater by liquid chromatography-high resolution mass spectrometry (LC-HRMS). Almost 200 substances were selected as "priority NPS" among those most frequently and recently reported by the Early Warning Systems (EWS) of different agencies and were included in the screening. Wastewater samples were collected from several cities all over Europe in 2016 and 2017, extracted using different solid-phase cartridges and analysed by LC-HRMS. The screening workflow comprised three successive analytical steps and compounds were identified and confirmed following specific criteria from the current guidelines. Thirteen NPS were identified at different confidence levels by using analytical standards or information from libraries and literature, and about half of them were phenethylamines. As far as we know, this is the first time that four of them (i.e. 3,4-dimethoxy-α-pyrrolidinovalerophenone, para-methoxyamphetamine, 2-phenethylamine and α-methyltryptamine) have been found in urban wastewater. The proposed screening approach was successfully applied in the largest NPS European wastewater monitoring, providing an innovative and easily adapted procedure for investigating NPS. In the light of current challenges and specific future research issues, this approach may complement epidemiological information and help in establishing measures for public health protection.

Suspect and non-target screening workflows to investigate the in vitro and in vivo metabolism of the synthetic cannabinoid 5Cl-THJ-018

The use of synthetic cannabinoids causes similar effects as Δ⁹ -tetrahydrocannabinol and long-term (ab)use can lead to health hazards and fatal intoxications. As most investigated synthetic cannabinoids undergo extensive biotransformation, almost no parent compound can be detected in urine, which hampers forensic investigations. Limited information about the biotransformation products of new synthetic cannabinoids makes the detection of these drugs in various biological matrices challenging. This study aimed to identify the main in vitro biotransformation pathways of 5Cl-THJ-018 and to compare these findings with an authentic urine sample of a 5Cl-THJ-018 user. The synthetic cannabinoid was incubated with pooled human liver microsomes and cytosol to simulate phase I and phase II biotransformations. Resulting extracts were analyzed with liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Three different data analysis workflows were applied to identify biotransformation products. A suspect screening workflow used an in-house database built from literature data and in silico biotransformation predictions. Two non-target screening workflows used a commercially available software and an open-source software for mass spectrometry data processing. A total of 23 in vitro biotransformation products were identified, with hydroxylation, oxidative dechlorination, and dihydrodiol formation pathways as the main phase I reactions. Additionally, five glucuronidated and three sulfated phase II conjugates were identified. The predominant in vivo pathway was through oxidative dechlorination and in total six metabolites of 5Cl-THJ-018 were identified. Biotransformation products both in vitro and in vivo were successfully identified using complementary suspect and non-target screening workflows.

Investigating in-sewer transformation products formed from synthetic cathinones and phenethylamines using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

Recent studies have demonstrated the role of biofilms on the stability of drug residues in wastewater. These factors are pertinent in wastewater-based epidemiology (WBE) when estimating community-level drug use. However, there is scarce information on the biotransformation of drug residues in the presence of biofilms and the potential use of transformation products (TPs) as biomarkers in WBE. The purpose of this work was to investigate the formation of TPs in sewage reactors in the presence of biofilm mimicking conditions during in-sewer transport. Synthetic cathinones (methylenedioxypyrovalerone, methylone, mephedrone) and phenethylamines (4-methoxy-methamphetamine and 4-methoxyamphetamine) were incubated in individual reactors over a 24h period. Analysis of parent species and TPs was carried out using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QToFMS). Identification of TPs was done using suspect and non-target workflows. In total, 18 TPs were detected and identified with reduction of β-keto group, demethylenation, demethylation, and hydroxylation reactions observed for the synthetic cathinones. For the phenethylamines, N- and O-demethylation reactions were identified. Overall, the experiments showed varying stability for the parent species in wastewater in the presence of biofilms. The newly identified isomeric forms of TPs particularly for methylone and mephedrone can be used as potential target biomarkers for WBE studies due to their specificity and detectability within a 24h residence time.

Studies on Para-Methoxymethamphetamine (PMMA) Metabolite Pattern and Influence of CYP2D6 Genetics in Human Liver Microsomes and Authentic Samples from Fatal PMMA Intoxications

Para-methoxymethamphetamine (PMMA) has caused numerous fatal poisonings worldwide and appears to be more toxic than other ring-substituted amphetamines. Systemic metabolism is suggested to be important for PMMA neurotoxicity, possibly through activation of minor catechol metabolites to neurotoxic conjugates. The aim of this study was to examine the metabolism of PMMA in humans; for this purpose, we used human liver microsomes (HLMs) and blood samples from three cases of fatal PMMA intoxication. We also examined the impact of CYP2D6 genetics on PMMA metabolism by using genotyped HLMs isolated from CYP2D6 poor, population-average, and ultrarapid metabolizers. In HLMs, PMMA was metabolized mainly to 4-hydroxymethamphetamine (OH-MA), whereas low concentrations of para-methoxyamphetamine (PMA), 4-hydroxyamphetamine (OH-A), dihydroxymethamphetamine (di-OH-MA), and oxilofrine were formed. The metabolite profile in the fatal PMMA intoxications were in accordance with the HLM study, with OH-MA and PMA being the major metabolites, whereas OH-A, oxilofrine, HM-MA and HM-A were detected in low concentrations. A significant influence of CYP2D6 genetics on PMMA metabolism in HLMs was found. The catechol metabolite di-OH-MA has previously been suggested to be involved in PMMA toxicity. Our studies show that the formation of di-OH-MA from PMMA was two to seven times lower than from an equimolar dose of the less toxic drug MDMA, and do not support the hypothesis of catechol metabolites as major determinants of fatal PMMA toxicity. The present study revealed the metabolite pattern of PMMA in humans and demonstrated a great impact of CYP2D6 genetics on human PMMA metabolism.

Qualitative screening for new psychoactive substances in wastewater collected during a city festival using liquid chromatography coupled to high-resolution mass spectrometry

The inclusion of new psychoactive substances (NPS) in the wastewater-based epidemiology approach presents challenges, such as the reduced number of users that translates into low concentrations of residues and the limited pharmacokinetics information available, which renders the choice of target biomarker difficult. The sampling during special social settings, the analysis with improved analytical techniques, and data processing with specific workflow to narrow the search, are required approaches for a successful monitoring. This work presents the application of a qualitative screening technique to wastewater samples collected during a city festival, where likely users of recreational substances gather and consequently higher residual concentrations of used NPS are expected. The analysis was performed using liquid chromatography coupled to high-resolution mass spectrometry. Data were processed using an algorithm that involves the extraction of accurate masses (calculated based on molecular formula) of expected m/z from an in-house database containing about 2,000 entries, including NPS and transformation products. We positively identified eight NPS belonging to the classes of synthetic cathinones, phenethylamines and opioids. In addition, the presence of benzodiazepine analogues, classical drugs and other licit substances with potential for abuse was confirmed. The screening workflow based on a database search was useful in the identification of NPS biomarkers in wastewater. The findings highlight the specific classical drugs and low NPS use in the Netherlands. Additionally, meta-chlorophenylpiperazine (mCPP), 2,5-dimethoxy-4-bromophenethylamine (2C-B), and 4-fluoroamphetamine (FA) were identified in wastewater for the first time.

Measuring biomarkers in wastewater as a new source of epidemiological information: Current state and future perspectives

The information obtained from the chemical analysis of specific human excretion products (biomarkers) in urban wastewater can be used to estimate the exposure or consumption of the population under investigation to a defined substance. A proper biomarker can provide relevant information about lifestyle habits, health and wellbeing, but its selection is not an easy task as it should fulfil several specific requirements in order to be successfully employed. This paper aims to summarize the current knowledge related to the most relevant biomarkers used so far. In addition, some potential wastewater biomarkers that could be used for future applications were evaluated. For this purpose, representative chemical classes have been chosen and grouped in four main categories: (i) those that provide estimates of lifestyle factors and substance use, (ii) those used to estimate the exposure to toxicants present in the environment and food, (iii) those that have the potential to provide information about public health and illness and (iv) those used to estimate the population size. To facilitate the evaluation of the eligibility of a compound as a biomarker, information, when available, on stability in urine and wastewater and pharmacokinetic data (i.e. metabolism and urinary excretion profile) has been reviewed. Finally, several needs and recommendations for future research are proposed.

Liquid chromatography-tandem mass spectrometry determination of synthetic cathinones and phenethylamines in influent wastewater of eight European cities

The popularity of new psychoactive substances (NPS) has grown in recent years, with certain NPS commonly and preferentially consumed even following the introduction of preventative legislation. With the objective to improve the knowledge on the use of NPS, a rapid and very sensitive method was developed for the determination of ten priority NPS (N-ethylcathinone, methylenedioxypyrovalerone (MDPV), methylone, butylone, methedrone, mephedrone, naphyrone, 25-C-NBOMe, 25-I-NBOMe and 25-B-NBOMe) in influent wastewater. Sample clean-up and pre-concentration was made by off-line solid phase extraction (SPE) with Oasis MCX cartridges. Isotopically labelled internal standards were used to correct for matrix effects and potential SPE losses. Following chromatographic separation on a C₁₈ column within 6 min, the compounds were measured by tandem mass spectrometry in positive ionization mode. The method was optimised and validated for all compounds. Limits of quantification were evaluated by spiking influent wastewater samples at 1 or 5 ng/L. An investigation into the stability of these compounds in influent wastewater was also performed, showing that, following acidification at pH 2, all compounds were relatively stable for up to 7 days. The method was then applied to influent wastewater samples from eight European countries, in which mephedrone, methylone and MDPV were detected. This work reveals that although NPS use is not as extensive as for classic illicit drugs, the application of a highly sensitive analytical procedure makes their detection in wastewater possible. The developed analytical methodology forms the basis of a subsequent model-based back-calculation of abuse rate in urban areas (i.e. wastewater-based epidemiology).

Quantitative Metabolite Profiling of an Amino Group Containing Pharmaceutical in Human Plasma via Precolumn Derivatization and High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry

Quantitative determination of the candidate drug molecule and its metabolites in biofluids and tissues is an inevitable step in the development of new pharmaceuticals. Because of the time-consuming and expensive nature of the current standard technique for quantitative metabolite profiling, i.e., radiolabeling followed by high-performance liquid chromatography (HPLC) with radiodetection, the development of alternative methodologies is of great interest. In this work, a simple, fast, sensitive, and accurate method for the quantitative metabolite profiling of an amino group containing drug (levothyroxine) and its metabolites in human plasma, based on precolumn derivatization followed by HPLC-inductively coupled plasma mass spectrometry (ICPMS), was developed and validated. To introduce a suitable "heteroelement" (defined here as an element that is detectable with ICPMS), an inexpensive and commercially available reagent, tetrabromophthalic anhydride (TBPA) was used for the derivatization of free NH₂-groups. The presence of a known number of I atoms in both the drug molecule and its metabolites enabled a cross-validation of the newly developed derivatization procedure and quantification based on monitoring of the introduced Br. The formation of the derivatives was quantitative, providing a 4:1 stoichiometric Br/NH₂ ratio. The derivatives were separated via reversed-phase HPLC with gradient elution. Bromine was determined via ICPMS at a mass-to-charge ratio of 79 using H₂ as a reaction gas to ensure interference-free detection, and iodine was determined at a mass-to-charge ratio of 127 for cross-validation purposes. The method developed shows a fit-for-purpose accuracy (recovery between 85% and 115%) and precision (repeatability <15% RSD). The limit of quantification (LoQ) for Br was approximately 100 μg/L.

Qualitative screening of new psychoactive substances in pooled urine samples from Belgium and United Kingdom

Concerns about new psychoactive substances (NPS) are increasing due to the rising frequency of serious intoxications. Analysis of biological fluids (urine) is necessary to get reliable information about the use of these substances. However, it is a challenging task due to the lack of analytical standards and the dynamic character of the NPS market. In the present work, a qualitative screening of NPS was carried out in 23 pooled urine samples collected from a city center in the UK and festivals in the UK and Belgium. The analytical method was based on data-independent acquisition mode using liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. An in-house library was used with >1500 entries corresponding to NPS, classical drugs and metabolites. All samples contained 53 and 28 compounds of interest from the UK and Belgium respectively. Of the different compounds detected, about 70% were confirmed using retention time and product ions while the remaining compounds were identified using elucidated fragmentation pathways. The highest numbers of NPS identified in both countries were from the cathinone and phenylethylamine families, with a higher number being detected in samples from the festival in the UK. Moreover, several cathinone metabolites in human urine were detected and identified. The screening method proved useful to detect a large number of compounds and determine the use of NPS.

New psychoactive substances: an overview on recent publications on their toxicodynamics and toxicokinetics

This review article covers English-written and PubMed-listed review articles and original studies published between January 2015 and April 2016 dealing with the toxicodynamics and toxicokinetics of new psychoactive substances. Compounds covered include stimulants and entactogens, synthetic cannabinoids, tryptamines, NBOMes, phencyclidine-like drugs, benzodiazepines, and opioids. First, an overview and discussion is provided on timely review articles followed by an overview and discussion on recent original studies. Both sections are then concluded by an opinion on these latest developments. This review shows that the NPS market is still highly dynamic and that the data published on their toxicodynamics and toxicokinetics can hardly keep pace with the appearance of new entities. However, data available are very helpful to understand and predict how NPS may behave in severe intoxication. The currently best-documented parameter is the in vitro metabolism of NPS, a prerequisite to allow detection of NPS in biological matrices in cases of acute intoxications or chronic consumption. However, additional data such as their chronic toxicity are still lacking.

High-resolution mass spectrometry in toxicology: current status and future perspectives

This paper reviews high-resolution mass spectrometry (HRMS) approaches using time-of-flight or Orbitrap techniques for research and application in various toxicology fields, particularly in clinical toxicology and forensic toxicology published since 2013 and referenced in PubMed. In the introduction, an overview on applications of HRMS in various toxicology fields is given with reference to current review articles. Papers concerning HRMS in metabolism, screening, and quantification of pharmaceuticals, drugs of abuse, and toxins in human body samples are critically reviewed. Finally, a discussion on advantages as well as limitations and future perspectives of these methods is included.

Identification of in vitro and in vivo human metabolites of the new psychoactive substance nitracaine by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

The purpose of this work was to investigate the in vitro metabolism of nitracaine, a new psychoactive substance, using human liver microsome incubations, to evaluate the cytochrome P450 (CYP) enzyme isoforms responsible for the phase-I metabolism and to compare the information from the in vitro experiments with data resulting from an authentic user's urine sample. Accurate mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and were used in the structural identification of metabolites. Two major and three minor phase-I metabolites were identified from the in vitro experiments. The observed phase-I metabolites were formed through N-deethylation, N,N-deethylation, N-hydroxylation, and de-esterification, with CYP2B6 and CYP2C19 being the main enzymes catalyzing their formation. One glucuronidated product was identified in the phase-II metabolism experiments. All of these metabolites are reported for the first time in this study except the N-deethylation product. All the in vitro metabolites except the minor N,N-deethylation product were also present in the human urine sample, thus demonstrating the reliability of the in vitro experiments in the prediction of the in vivo metabolism of nitracaine. In addition to the metabolites, three transformation products (p-nitrobenzoic acid, p-aminobenzoic acid, and 3-(diethylamino)-2,2-dimethylpropan-1-ol) were identified, as well as several glucuronides and glutamine derived of them.

Annual banned-substance review: analytical approaches in human sports drug testing

The aim of improving anti-doping efforts is predicated on several different pillars, including, amongst others, optimized analytical methods. These commonly result from exploiting most recent developments in analytical instrumentation as well as research data on elite athletes' physiology in general, and pharmacology, metabolism, elimination, and downstream effects of prohibited substances and methods of doping, in particular. The need for frequent and adequate adaptations of sports drug testing procedures has been incessant, largely due to the uninterrupted emergence of new chemical entities but also due to the apparent use of established or even obsolete drugs for reasons other than therapeutic means, such as assumed beneficial effects on endurance, strength, and regeneration capacities. Continuing the series of annual banned-substance reviews, literature concerning human sports drug testing published between October 2014 and September 2015 is summarized and reviewed in reference to the content of the 2015 Prohibited List as issued by the World Anti-Doping Agency (WADA), with particular emphasis on analytical approaches and their contribution to enhanced doping controls.