Ketamine analogues: Comparative toxicokinetic in vitro-in vivo extrapolation and quantification of 2-fluorodeschloroketamine in forensic blood and hair samples

Monitoring the dynamics of ketamine analogues use in China through wastewater analysis: The emergence of 2-FDCNEK and 2-MDCK

Ketamine analogues are rapidly emerging around the world and are considered one of the new psychoactive substances (NPS) of greatest concern. However, little is known about their actual use at the community level and their evolution on the drug market. Wastewater-based epidemiology is a useful tool to explore the profile of NPS use. Influent wastewater samples were collected from 21 cities in Southwest China between 2022 and 2023, and ketamine analogues were determined by liquid chromatography-tandem mass spectrometry. Results showed that five ketamine analogues were detected in at least one wastewater sample from 19 cities, of which four new analogues were found in wastewater for the first time. 2-fluoro deschloro-N-ethyl-ketamine (2-FDCNEK) was the most frequently detected analogue, with a population-normalized mass load of up to 3.18 mg day-1 1000 inh-1. The remaining analogues were detected less frequently, with mass loads of almost below 1 mg day-1 1000 inh-1. 2-fluoro deschloroketamine (2-FDCK), which was classified as a controlled substance in 2021, showed an evident downward trend. Furthermore, 2-(methylamino)-2-(2-methyphenyl)-cyclohexanone (2-MDCK) disappeared within a short period, whereas 2-FDCK and 2-FDCNEK persisted over the two-year observation period, suggesting that ketamine analogues containing halogen atoms on the phenyl group may have psychoactive effects similar to those of ketamine, with a high potential for abuse. These findings highlight the importance of wastewater analysis in monitoring the dynamic profile of NPS use, providing valuable information for authorities to take measures to prevent the rapid spread of NPS and minimize health risks.

Fluorodeschloroketamine found as a street drug in drug seizures and drug driving cases in Hong Kong

BACKGROUND

With the decline of the use of ketamine, one of the common drugs of abuse in Hong Kong, detection of ketamine-related analogues in local laboratories has been encountered.

AIM

A brief account of the occurrence of fluorodeschloroketamine (FDCK) in forensic cases is reported through a retrospective study of all drug seizures and driving under the influence of drugs (DUID) cases since its first appearance.

METHODS

Identification of FDCK in drug seizures was achieved through gas chromatography - mass spectrometry (GC-MS) and/or liquid chromatography - diode array detection (LC-DAD) methods while its quantification was performed using gas chromatography - flame ionization detection (GC-FID). For the analysis of blood samples in DUID cases, identification and quantification were performed using LC-MS/MS by monitoring the respective transitions of FDCK and fluorodeschloronorketamine (FDCNK) using ketamine-d4 and norketamine-d4 respectively as internal standards.

RESULTS

Since its first submission in November 2018, a total of 74 drug seizure cases (151 items) and 6 drug driving cases were encountered till December 2019. Drug seizures found with FDCK were physically similar to those of ketamine seizures. The majority of items were detected with FDCK only (103 items, ∼67%) or as a mixture of FDCK with ketamine (42 items, ∼28%). The drug purity detected with either FDCK only or FDCK mixed with ketamine was high which was similar to those purity found in ketamine seizures. The blood drug concentrations of FDCK of the 6 drug driving cases were in the range of <0.002-1.1 μg/mL and other psychoactive drug(s)/metabolite(s) were also identified. Except for one case where the analysis of the metabolite, fluorodeschloronorketamine (FDCNK), was not conducted due to insufficient sample, the FDCK (FDCNK) concentrations in blood found in the 6 cases were <0.002 (0.005), 0.002 (0.002), 0.002 (0.003), 0.02 (0.035), 0.87 (0.44) and 1.1 (not determined) μg/mL.

CONCLUSIONS

With the drug seizures found with FDCK resembled in physical appearance with ketamine seizures, users might likely misuse it as ketamine. Though complicated by other drugs found, it is speculated that the two cases with higher concentration of FDCK found in blood (1.1 and 0.87 μg/mL) might have contributed to the impairment observed.

Green Analytical Toxicology procedure for determination of ketamine, its metabolites and analogues in oral fluid samples using dispersive liquid-liquid microextraction (DLLME)

New psychoactive substances (NPS) are often synthesized via small changes in the molecular structure, producing drugs whose effect and potency are not yet fully known. Ketamine is one of the oldest NPS, with therapeutic use in human and veterinary medicine authorized in several countries, being metabolized mainly into norketamine and 6-hydroxy-norketamine. Furthermore, two structural analogues of ketamine have recently been identified, deschloroketamine and 2-fluorodeschloroketamine, marketed as drugs of abuse. To comply with Green Analytical Toxicology (GAT) fundamentals, miniaturized techniques such as dispersive liquid-liquid microextraction (DLLME) were employed to determine toxicants in biological fluids. An analytical method for determining ketamine, its metabolites and its analogues in oral fluid was fully developed and validated by using DLLME and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The extraction parameters were optimized by multivariate analysis, obtaining the best conditions with 200 μL of sample, 100 μL of methanol as dispersive solvent and 50 μL of chloroform as extractor solvent. Linearity was obtained from 10 to 1,000 ng/mL, with limit of detection (LOD) and lower limit of quantification (LLOQ) at 10 ng/mL. Imprecision (% relative standard deviation) and bias (%) were less than 8.2% and 9.5%, respectively. The matrix effect did not exceed 10.6%, and the recovery values varied from 24% to 42%. No matrix interference and good selectivity in the evaluation of 10 different sources of oral fluid and 42 drugs at 500 ng/mL, respectively, were observed. The method was applied in the analysis of 29 authentic oral fluid samples and had its green characteristic evaluated by three different tools: the Green Analytical Procedure Index (GAPI), the Analytical Eco-Scale and the Analytical GREEnness (AGREE) metrics.

2-Fluorodeschloroketamine consumption: About two deaths and a case of self-mutilation

2-Fluorodeschloroketamine (2-FDCK) is a new psychoactive substance (NPS), close to the ketamine structure. Few cases of 2-FDCK intake are described in the forensic literature, especially concerning death cases. We report here a case of self-mutilation (Case 1) and two forensic deaths linked to 2-FDCK consumption. The second case involved a man found dead in the street, having been stabbed. The third case was a man found dead following a suspected overdose and in an advanced state of putrefaction. For all three cases, biological fluids such as blood and urine were analyzed, as was hair for the two fatal cases. The aim of this study was to identify and quantify 2-FDCK and its main metabolites in different matrices. Biological fluids and hair were analyzed by liquid chromatography coupled with tandem mass spectrometry after decontamination and extraction. Seized products were analyzed by gas chromatography-mass spectrometry and assayed, when possible, by ultra-performance liquid chromatography with diode-array detection. 2-FDCK was detected and quantified in the peripheral blood of Cases 1, 2 and 3 (457, 758 and 5885 µg/L, respectively), as were its main metabolites nor-2-FDCK, dihydro-nor-2-FDCK and dihydro-2-FDCK. In the 1 cm long hair of Cases 2 and 3, 2-FDCK was also detected (approximately 4149 and 79824 pg/mg, respectively). Deschloroketamine (DCK) was found in the biological fluids of Cases 1, 2 and 3 (10, 8 and 350 µg/L, respectively), as well as in hair of Cases 2 and 3 (65 and around 8119 pg/mg, respectively). In Case 3, as a small bag containing DCK powder was seized from his home, we can assume that DCK was taken. On the contrary, to our knowledge, it has not been established that Case 2 took DCK alone, so we can assume that it may be the first case to report DCK from 2-FDCK metabolism in fluids as well as in hair.

Screening strategy for ketamine-based new psychoactive substances using fragmentation characteristics from high resolution mass spectrometry

Recreational designer drugs called new psychoactive substances (NPS) are emerging and pose enormous risks to public health. Detection of recently discovered or unreported NPS remains a huge challenge by using traditional targeted mass spectrometry methods. Here a novel screening strategy was developed to detect both known and novel analogs of NPS based on fragmentation characteristics from liquid chromatography-high resolution mass spectrometry (LC-HRMS). The HRMS fragmentation pathway of one selected NPS family was investigated to form a database containing predicted drugs as well as their mass characteristics. During the study, an unexpected substituent effect was found to distinguish geometric isomers. Seventy-eight seized samples were analyzed using this strategy, four ketamine-based NPS were detected and three of them were newly marketed. The substituent effect predicted the position of their phenylic substituent, the results were confirmed by NMR.

Case report: Identification of AP-238 and 2-fluorodeschloroketamine in internet available powder samples sold as bucinnazine

Novel synthetic opioids (NSOs) are a class of opioid agonists that include analogs of fentanyl and structurally distinct non-fentanyl compounds normally used as standalone products, heroin adulterants, or constituents of counterfeit pain pills. Most NSOs are not currently scheduled in the U.S., are predominantly illegally synthesized, and sold on the Darknet. Among them, the cinnamylpiperazine derivatives such as bucinnazine (AP-237), AP-238, and 2-methyl-AP-237 and the arylcyclohexylamine derivatives, analogs of ketamine, such as 2-fluoro-deschloroketamine (2 F-DCK) have appeared in several monitoring systems. Two white powders purchased on the internet as bucinnazine were first analyzed with polarized light microscopy followed by direct analysis in real time-mass spectrometry (DART-MS) and gas chromatography-mass spectrometry (GC-MS). Both powders were white crystals with no other significant microscopic properties. The DART-MS analysis showed the presence of 2-fluorodeschloroketamine in powder #1, and AP-238 in powder #2. Identification was confirmed by GC-MS. The purity of each substance was 78.0% for powder #1, and 88.9% for powder #2, respectively. The toxicological risk associated with the misuse of NSOs still needs further study. The absence of bucinnazine and the presence of different active compounds in internet purchased samples raises public health and safety concerns.

Microextraction by Packed Sorbent as a Clean-up Approach for the Determination of Ketamine and Norketamine in Hair by Gas Chromatography--Tandem Mass Spectrometry

The use of new psychoactive substances has been increasing and constitutes a social and public health problem, and hence, toxicological analysis has become of utmost importance for the detection of such substances. In this article, we present the development and full validation of a simple, user and environmentally friendly, cheap and suitable method for the determination of ketamine and its main metabolite norketamine in hair samples. The procedure included using a miniaturized procedure-microextraction by packed sorbent with mixed-mode sorbent-for sample clean-up. Organic solvents use was minimal, and it was possible to obtain a linear method (0.05-10 ng/mg for both analytes). The extraction efficiency ranged from 32 to 61%, which did not impair sensitivity. The method proved to be selective, precise, accurate and suitable for routine analysis for the determination of said compounds in 50-mg hair samples.

Arylcyclohexylamine Derivatives: Pharmacokinetic, Pharmacodynamic, Clinical and Forensic Aspects

Since the 2000s, an increasing number of new psychoactive substances (NPS) have appeared on the drug market. Arylcyclohexylamine (ACH) compounds such as ketamine, phencyclidine and eticyclidine derivatives are of particular concern, given their rapidly increasing use and the absence of detailed toxicity data. First used mainly for their pharmacological properties in anesthesia, their recreational use is increasing. ACH derivatives have an antagonistic activity against the N-methyl-D-aspartate receptor, which leads to dissociative effects (dissociation of body and mind). Synthetic ketamine derivatives produced in Asia are now arriving in Europe, where most are not listed as narcotics and are, thus, legal. These structural derivatives have pharmacokinetic and pharmacodynamic properties that are sometimes very different from ketamine. Here, we describe the pharmacology, epidemiology, chemistry and metabolism of ACH derivatives, and we review the case reports on intoxication.

A comparison of reinforcing effectiveness and drug-seeking reinstatement of 2-fluorodeschloroketamine and ketamine in self-administered rats

2-Fluorodeschloroketamine (2F-DCK), a structural analog of ketamine, has been reported to cause impaired consciousness, agitation, and hallucination in abuse cases. It has similar reinforcing and discriminative effects as ketamine. However, the reinforcing efficacy and drug-seeking reinstatement of this analog have not been clarified to date. In this study, the effectiveness of 2F-DCK and ketamine was compared using a behavioral economics demand curve. The reinstatement of 2F-DCK- and ketamine-seeking behaviors induced by either conditioned cues or self-priming was also analyzed. Rats were intravenously self-administered 2F-DCK and ketamine at a dose of 0.5 mg/kg/infusion under a reinforcing schedule of fixed ratio 1 (FR1) with 4 h of daily training for at least 10 consecutive days. The elasticity coefficient parameter α and the essential value of the demand curve in the two groups were similar. Both groups of rats showed significant drug-seeking behavior induced either by conditional cues or by 2F-DCK and ketamine priming. Moreover, the α parameter was inversely related to the degree of reinstatement induced by cues or drug priming in both groups. In total, the expression levels of brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element-binding protein (p-CREB) in the nucleus accumbens in both extinguished and reinstated rats were significantly lower than those in the control. The expression of total Akt, glycogen synthase kinase (GSK)-3β, mammalian target of rapamycin (mTOR), and extracellular signal-related kinase (ERK) also decreased, but p-Akt, p-GSK-3β, p-mTOR, and p-ERK levels increased in both extinguished and reinstated rats. This is the first study to demonstrate that 2F-DCK has similar reinforcing efficacy, effectiveness, and post-withdrawal cravings as ketamine after repeated use. These data suggest that the downregulation of CREB/BDNF and the upregulation of the Akt/mTOR/GSK-3β signaling pathway in the nucleus accumbens may be involved in ketamine or 2F-DCK relapse.

Reports of Adverse Events Associated with Use of Novel Psychoactive Substances, 2017-2020: A Review

An important role of modern forensic and clinical toxicologists is to monitor the adverse events of novel psychoactive substances (NPS). Following a prior review from 2013 to 2016, this critical literature review analyzes and evaluates published case reports for NPS from January 2017 through December 2020. The primary objective of this study is to assist in the assessment and interpretation of these cases as well as provide references for confirmation methods. Chemistry, pharmacology, adverse events and user profiles (e.g., polypharmacy) for NPS are provided including case history, clinical symptoms, autopsy findings and analytical results. Literature reviews were performed in PubMed and Google Scholar for publications using search terms such as NPS specific names, general terms (e.g., 'designer drugs' and 'novel psychoactive substances'), drug classes (e.g., 'designer stimulants') and outcome-based terms (e.g., 'overdose' and 'death'). Government and website drug surveillance databases and abstracts published by professional forensic science organizations were also searched. Toxicological data and detailed case information were extracted, tabulated, analyzed and organized by drug category. Case reports included overdose fatalities (378 cases), clinical treatment and hospitalization (771 cases) and driving under the influence of drugs (170 cases) for a total of 1,319 cases providing details of adverse events associated with NPS. Confirmed adverse events with associated toxidromes of more than 60 NPS were reported including synthetic cannabinoid, NPS stimulant, NPS hallucinogen, NPS benzodiazepine and NPS opioid cases. Fifty of these NPS were reported for the first time in January 2017 through December 2020 as compared to the previous 4 years surveyed. This study provides insight and context of case findings described in the literature and in digital government surveillance databases and websites during a recent 4-year period. This review will increase the awareness of adverse events associated with NPS use to better characterize international emerging drug threats.

IVIVE: Facilitating the Use of In Vitro Toxicity Data in Risk Assessment and Decision Making

During the past few decades, the science of toxicology has been undergoing a transformation from observational to predictive science. New approach methodologies (NAMs), including in vitro assays, in silico models, read-across, and in vitro to in vivo extrapolation (IVIVE), are being developed to reduce, refine, or replace whole animal testing, encouraging the judicious use of time and resources. Some of these methods have advanced past the exploratory research stage and are beginning to gain acceptance for the risk assessment of chemicals. A review of the recent literature reveals a burst of IVIVE publications over the past decade. In this review, we propose operational definitions for IVIVE, present literature examples for several common toxicity endpoints, and highlight their implications in decision-making processes across various federal agencies, as well as international organizations, including those in the European Union (EU). The current challenges and future needs are also summarized for IVIVE. In addition to refining and reducing the number of animals in traditional toxicity testing protocols and being used for prioritizing chemical testing, the goal to use IVIVE to facilitate the replacement of animal models can be achieved through their continued evolution and development, including a strategic plan to qualify IVIVE methods for regulatory acceptance.

2-Fluorodeschloroketamine has similar abuse potential as ketamine

2-Fluorodeschloroketamine (2-FDCK) as a substitute for ketamine has emerged among drug abusers in recent years. However, 2-FDCK has not been controlled or regulated in many countries, which may be partly related to the lack of evidence on its abuse potential. In this study, we evaluated the abuse potential of 2-FDCK via the tests of the conditioned place preference (CPP), locomotor sensitization, drug self-administration and drug discrimination using ketamine as a reference. 2-FDCK induced significant CPP at a minimum dose of 3 mg/kg in mice, an effect comparable with that of ketamine (3 mg/kg). Acute injections of 2-FDCK or ketamine at 30 mg/kg enhanced locomotor activity. Repeated treatments with this dose of 2-FDCK and ketamine induced locomotor sensitization after withdrawal. 2-FDCK readily induced self-administration with 0.5 mg/kg/infusion, the same dose for ketamine, and induced the highest seeking response at 1 mg/kg. Drug discrimination test showed that 2-FDCK dose-dependently substitute for ketamine with comparable ED₅₀ to ketamine in substitution testing. Taken together, these results strongly suggested that 2-FDCK has an abuse potential comparable with ketamine.

Structure identification and analysis of the suspected chemical precursor of 2-fluorodeschloroketamine and its decomposition products

In this work, 1-[(2"-fluorophenyl)(methylimino) methyl]cyclopentan-1-ol (2-fluorodeschlorohydroxylimine) was identified as a suspected chemical precursor of 2-fluorodeschloroketamine (2-FDCK) using GC-MS and GC-Q/TOF-MS and comparing the data with those of ketamine and its chemical precursor, hydroxylimine. Furthermore, the entire fragmentation pathway of 2-fluorodeschlorohydroxylimine was theorized from the GC-MS spectrum recorded using an electron ionization (EI) source, and the mechanisms and decomposition pathways of 2-fluorodeschlorohydroxylimine were elucidated. In protic solvents, the nitrogen atom in the C=N group of 2-fluorodeschlorohydroxylimine underwent a protonation reaction. Thereafter, the traces of water present in protic solvents promoted the hydrolysis of the protonated imine, and a carbon cation was obtained following the loss of methylamine. The carbon cation could follow the classical decomposition mechanism of imines and yield an α-hydroxyl ketone, which was the major decomposition product, (2'-fluorophenyl)(1"-hydroxycyclopentyl) methanone. The cation could also undergo a loop expansion rearrangement and yield another α-hydroxyl ketone, 2-(2'-fluorophenyl)-2-hydroxycyclohexan-1-one. The structures of the two aforementioned decomposition products were elucidated using several techniques including theoretical calculation, GC-MS, NMR, the prediction and assistance elucidation functions of ACDLabs-Structure Elucidator Suite, and the virtual separation technology of diffusion-ordered spectroscopy. The aforementioned study revealed important information about the chemical precursor of 2-FDCK and its decomposition. Furthermore, a set of methods for the qualitative analysis of 2-fluorodeschlorohydroxylimine was established, which facilitated accurate analysis of 2-fluorodeschlorohydroxylimine samples following decomposition or destruction.

A Psychonaut's Experience of Intoxication with Multiple Classes of Drugs Including Novel Psychoactive Substance 2-fluorodeschloroketamine: Case Report and Urinary Analysis

Novel psychoactive substances have emerged as drugs of abuse. 2-Fluorodeschloroketamine (2-FDCK) is a ketamine derivative that can be purchased online for as little as $12 per gram. We report the case of a patient with a history of polysubstance use presenting after insufflation of 2-FDCK, with subsequent confirmation of metabolites in the patient's urine. A 28-year-old man presented to the Emergency Department in a dissociated state. He recovered well with supportive care, and described during interview his experience of substance use including the novel psychoactive substance 2-FDCK. A urine sample was sent for analysis and 2-FDCK metabolites were isolated. This case is concerning because 2-FDCK is a relatively new agent that has not yet been reported in the United States. It is easy to obtain over the internet and has significant abuse potential.

Metabolite elucidation of 2-fluoro-deschloroketamine (2F-DCK) using molecular networking across three complementary in vitro and in vivo models

This work first aims to investigate metabolites of 2-fluoro-deschloroketamine (2F-DCK), a new arylcyclohexylamine derivatives (a group of dissociative ketamine-based substances) using two in vitro experimental approaches, and to compare obtained results by means of molecular networking. Metabolites of 2F-DCK were investigated using both human liver microsomes (HLMs) and hepatic (HepaRG) cell line incubates using molecular networking approach: 2F-DCK pure substance was incubated with HLMs for up to 1 h at two concentrations (100 and 500 μM) and with HepaRG cells for two time periods (8 and 24 h) at one concentration (20 μM). In vitro obtained results were subsequently applied to a 2F-DCK-related fatality case. In vitro-produced metabolites were investigated using high-resolution accurate mass spectrometry using Orbitrap mass analyzer technology. Thirteen metabolites were in vitro produced and several metabolic pathways can be postulated. Seven additional metabolites were found in post-mortem samples (bile and urine) of the case, comprising three Phase II metabolites, which appear to be minor in vivo metabolites. HLMs and HepaRG cell models appear to be complementary and obtained data allowed the identification of several specific 2F-DCK metabolites in biological samples. In practical terms, observed metabolic ratios suggested that nor-2F-DCK (208.1137 m/z) and a hydrogenated metabolite (224.1443 m/z) could be proposed as reliable metabolites to be recorded in HRMS libraries in order to improve detection of 2F-DCK use.

Increasing Prevalence of Ketamine in Drivers in New York City Including the Identification of 2-Fluoro-Deschloroketamine

Ketamine is a dissociative anesthetic used in veterinary and human medicine since the 1970s. Its clinical use has expanded to control of seizures, pre-hospital emergency medical services (EMS), and is finding new purpose as an analgesic alternative and antidepressant. Ketamine brings hope for effective management of chronic pain in the absence of opioids, and decreasing suicidal ideations, however, its persistence as a recreational drug for its hallucinogenic properties remains. In the wake of expanding medicinal purposes, the diversity of New York City's population was explored to better understand its misuse. This retrospective study looks at the prevalence of ketamine in driver fatalities over a period of 18 years (2003-2020) and cases involving suspected driving under the influence of drugs (DUID) over a period of 6 years (2015-2020). Ketamine was identified in 6 driver fatalities and in 47 DUID cases. None of the driver fatalities were suspected of ketamine misuse, due to administration either in hospital or EMS administration. In the DUID cases, an increasing trend was observed over the 6-year study period with 100% (N = 47) of the cases confirmed as non-hospital/non-EMS administered ketamine. Of the DUID cases, 94% were male, with the majority between the age of 21-39 years (85%) and were predominantly Hispanic (36%) and Asian (34%). Blood concentrations of ketamine ranged from 27 to > 2000 ng/mL with polydrug use prevalent. The most common drug classes detected in addition to ketamine were cannabinoids (38%), ethanol (32%), benzodiazepines (26%), cocaine (19%), and amphetamines/MDMA (15%). In 2019, 2-fluoro-deschloroketamine (2F-DCK) was identified in two cases for the first time. Despite its increased acceptance for mental health disorders, ketamine's persistence and misuse as a recreational drug remains and should continue to be monitored by relevant toxicological, clinical, and law enforcement communities along with emerging illicit ketamine analogs.

Fatal intoxication related to two new arylcyclohexylamine derivatives (2F-DCK and 3-MeO-PCE)

Continuous development and rapid turnover of drug market of new psychoactive substances (NPS) make it difficult to obtain up-to-date analytical methods for efficient detection of intoxication cases with new substances: no analytical data and no previously published concentration values in biological samples are indeed available. In this context, we aim to report the first fatal case involving two newly emerging arylcyclohexylamine derivatives (a group of dissociative ketamine-based substances): 2-fluoro-deschloroketamine (2F-DCK) and 3-methoxyeticyclidine (3-MeO-PCE). A 42-year-old man was found dead at his home with three plastic bags of "research chemicals" powders near him. Comprehensive screenings of drugs and toxic compounds as well as more selective assays (performed using NMR, HS-GC-FID, LC-MS/MS and LC-HRMS methods) allowed (1) to identify the three unknown powders, 2F-DCK, 3-MeO-PCE, and 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT, a hallucinogenic tryptamine-related NPS), with purity above 95%, and (2) to determine peripheral blood (1780, 90, and 52 µg/L), urine (6.1, 6.3, and 2.2 mg/L), bile (12, 3.5, and 1.7 mg/L), and vitreous humour (1500, 66 and 155 µg/L) concentrations of 2F-DCK, 3-MeO-PCE and 5-MeO-DMT, respectively. In addition, toxicological results also revealed recent use of cannabis, cocaine, and amphetamine by the victim, and hair analysis draw pathway of addiction (including experiments with various other NPS) for several months before death. This fatality was considered as the consequence of respiratory depression in a poly-drug user due to a "cocktail effect" of concurrent intakes of 2F-DCK (mainly), 3-MeO-PCE, 5-MeO-DMT, amphetamine, and cocaine. In addition, this case report provides analytical data that could support subsequent toxicological result interpretation in forensic cases involving such arylcyclohexylamine derivatives.

Presence of the ketamine analog of 2-fluorodeschloroketamine residues in wastewater

Ketamine (KET) analogs are increasingly emerging as new psychoactive substances (NPS). The present report describes the first detection of the KET analog, 2-fluorodeschloroketamine (2F-DCK), in influent samples collected from nine wastewater treatment plants in seven major Chinese cities from 2018 to 2020 by wastewater-based epidemiology (WBE). An analytical method based on solid-phase extraction and subsequent gas chromatography-mass spectrometry was developed for the detection of 2F-DCK and KET. The stability experiments showed that 2F-DCK and KET remained stable in wastewater for 15 days at room and frozen temperatures, and at two pH values (pH = 7 and pH = 2), with residue amounts between 90% and 110%. KET was detected in all samples, whereas 2F-DCK was detected in only four samples: from Guangzhou in 2018, Shenzhen in 2019, and Quanzhou and Nanning in 2020, indicating that 2F-DCK has been used as early as 2018 in China. The renal clearance of 2F-DCK was predicted based on the quantitative structure-pharmacokinetic relationship model, which was used to calculate an excretion factor of 3.7. The 2F-DCK consumption in four cities ranged from 3.71 ± 0.05 to 55 ± 0.09 mg/day/1000 inh, and KET ranged from 1.3 ± 0.04 to 76.5 ± 4.63 mg/day/1000 inh. This is the first study to investigate 2F-DCK by WBE, which provides relevant real-time data on the growth of NPS use, as well as useful information for the government to develop new policies.

Method development for the identification of methoxpropamine, 2-fluoro-deschloroketamine and deschloroketamine and their main metabolites in blood and hair and forensic application

The constant increase of new psychoactive substances, often available on the illicit drug market as 'research chemicals', poses a concern for public health and a significant analytical and legislative challenge. Β-keto-arylcyclohexamines represent a class of dissociative anesthetics recently introduced on the market of New Psychoactive Substances (NPS). There is still a lack of information about the pharmacological activity of many of such substances, usually depending on the potential chemical modifications introduced to circumvent the law. Furthermore, their intake may not be fully intentional, since consumers do not always have knowledge of the content of online purchases. The present study describes the characterization by liquid chromatography-high resolution mass spectrometry (LC-HRMS), using a benchtop Orbitrap instrument, of the novel ketamine analogues methoxpropamine, 2-fluoro-deschloroketamine and deschloroketamine, found in the post-mortem blood and hair samples from a forensic case of suicide by fall from height, and of some of their metabolites. This allowed the development of analytical methods for the determination of both the β-keto-arylcyclohexamines and the metabolites in LC-HRMS and in LC-MS/MS, providing a starting point for studying their toxicokinetics.

Emergence of new psychoactive substance 2-fluorodeschloroketamine: Toxicology and urinary analysis in a cluster of patients exposed to ketamine and multiple analogues

New psychoactive substances (NPS) emerge continually, amongst which is a growing class of ketamine analogues with an arylcyclohexylamine backbone. Recently we reported a poisoning outbreak associated with 2-oxo-PCE (deschloro-N-ethyl-ketamine). The present report describes the emergence of another ketamine analogue, 2-fluorodeschloroketamine (2F-DCK). The compound was first detected in a patient's urine, its identity confirmed by accurate mass analysis and comparison with reference standard. Four putative metabolites were identified, including nor-2F-DCK, dehydronor-2F-DCK (major metabolite) and two hydroxylated derivatives of nor-2F-DCK. Between January and July 2019, 20 cases of analytically confirmed 2F-DCK exposure were encountered. In 19 out of 20 cases, at least one more ketamine-type drug was detected concurrently with 2F-DCK, including ketamine (90%), deschloroketamine (DCK, 50%), 2-oxo-PCE (45%) and tiletamine (10%). In particular, six of the cases showed the presence of 4 ketamine-type drugs in the same urine sample. The clinical effects observed in patients exposed to 2F-DCK are predominantly neurological (impaired consciousness, agitation, abnormal behaviour) and cardiovascular (hypertension, tachycardia); five patients had loss of consciousness or convulsion. Management was mainly supportive; all patients recovered uneventfully. This is the first clinical case series involving 2F-DCK and frontline medical personnel are urged to be aware of this rapidly expanding class of NPS, in particular the co-ingestion of multiple ketamine analogues.