Postmortem concentrations of the synthetic opioid U-47700 in 26 fatalities associated with the drug

Intoxications involving methoxyacetylfentanyl and U-47700: a study of 3 polydrug fatalities

Novel synthetic opioids (NSOs) represent an emerging group of novel psychoactive substances, acting as agonists at the opioid receptors. NSOs include fentanyl-related compounds, e.g. methoxyacetylfentanyl (MeACF), and non-fentanyl analogs, e.g. "U compounds" including U-47700. Here we present three cases of death involving MeACF and U-47700, with particular reference to preliminary data on pharmacokinetics and tissue distribution.After a complete post-mortem examination, general unknown screenings and analysis of drugs of abuse were performed on postmortem samples by immunoassays, gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. To quantify the analytes of interest in post-mortem blood and tissues, the standard addition method was used. A toxicological significance score (TSS), weighing the role of the NSO in each death case, was assigned.Case 1 died at the hospital after consumption of U-47700, methadone (serum levels: 2,600 ng/ml and 37 ng/ml), tilidine and benzodiazepines. In case 2, U-47700 (204 ng/ml) together with methadone (290 ng/ml), flubromazepam (480 ng/ml) and diazepam (300 ng/ml) were detected in peripheral blood. In case 3, methoxyacetylfentanyl (266 ng/ml), furanylfentanyl (4.3 ng/ml) 4-ANPP (15 ng/ml) and alprazolam (69 ng/ml) were quantified in femoral blood. In all cases, the NSO likely contributed to the death (TSS = 3).NSOs appear to be often consumed in the setting of polydrug intoxications, especially in combination with other opioids and benzodiazepines, which often exert synergistic effects. The standard addition method remains the most reliable in post-mortem analysis and toxicological results should always be evaluated together with circumstantial and autopsy data.

Non-fentanyl new synthetic opioids - An update

BACKGROUND

New synthetic opioids (NSO) constitute one of the fastest-growing group of New Psychoactive Substances, which emerged on the illicit drug marker in the second half of 2000's. The most popular and the largest NSO subgroup are high potency fentanyl and its analogs. Subsequent to core-structure scheduling of fentanyl-related substances many opioids with different chemical structures are now emerging on the illicit drug market, rendering the landscape highly complex and dynamic.

METHODS

PubMed, Scopus and Google Scholar were searched for appropriate articles up to December 2022. Moreover, a search for reports was conducted on Institutional websites to identify documentation published by World Health Organization, United Nations Office on Drugs and Crime, United States Drug Enforcement Administration, and European Monitoring Centre for Drugs and Drug Addiction. Only articles or reports written in English were selected.

RESULTS

Non-fentanyl derived synthetic opioids, i.e., 2-benzylbenzimidazoles (nitazenes), brorphine, U-compounds, AH-7921, MT-45 and related compounds are characterized, describing them in terms of available forms, pharmacology, metabolism as well as their toxic effects. Sample procedures and analytical techniques available for detection and quantification of these compounds in biological matrices are also presented. Finally, as overdoses involving highly potent NSO may be difficult to reverse, the effectiveness of naloxone as a rescue agent in NSO overdose is discussed.

CONCLUSIONS

Current review presents key information on non-fentanyl derived NSO. Access to upto-date data on substances of abuse is of great importance for clinicians, public health authorities and professionals performing analyses of biological samples.

"Spice"-related deaths in and around Munich, Germany: A retrospective look at the role of synthetic cannabinoid receptor agonists in our post-mortem cases over a seven-year period (2014-2020)

Synthetic cannabinoid receptor agonists (SCRAs, "Spice") are a diverse group of recreational drugs, with their structural and pharmacological variability still evolving. Forensic toxicologists often rely on previous reports to assess their role in intoxication cases. This work provides detailed information on the "Spice"-related fatalities around Munich, Germany, from 2014 to 2020. All cases underwent an autopsy. Pharmaceutical and illicit drugs were detected and quantified in post-mortem peripheral blood or liver by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on circumstantial evidence, only those cases for which a prior consumption was suspected underwent additional analyses for SCRAs and other new psychoactive substances in post-mortem blood, liver or antemortem specimens. Drug concentrations, pathological findings at autopsy and case histories were considered to assess and rank the SCRAs' involvement in each death. Concentration ranges for the individual substances in blood were defined and their distribution patterns over the investigated period were determined and correlated with their legal status and local police seizures. We identified 41 different SCRAs among 98 fatalities. 91.8% were male, at a median age of 36 years. SCRAs played a causative role in 51%, contributory role in 26%, and an insignificant role in 23% of cases. In correlation with local police seizures and legal status, 5F-ADB was the most prevalent in our cases, followed by 5F-MDMB-PICA and AB-CHMINACA. Cumyl-CBMICA and 5F-MDMB-P7AICA were among the least frequently detected SCRAs. "Spice"-related fatalities and SCRAs' causative role have significantly decreased among our cases since the German New Psychoactive Substances Act.

In the case of extensively putrefied bodies, the analysis of entomological samples may support and complement the toxicological results obtained with other alternative matrices

Entomotoxicological analysis is not part of routine toxicological analysis. This work aims to present two cases to illustrate the potential of entomological samples as complementary matrices to identify substances in cases of advanced putrefaction. (Case#1) A woman wasexhumed after 14 months to ascertain the exact cause of death. She died after six weeks of hospitalization because of intestinal ischemia followed by multiorgan failure. (Case#2) The corpse of a woman, known to have a psychiatric disorder, was discovered in her apartment. The state of decomposition of the body was consistent with a post-mortem period of several weeks (approximately 6 weeks). Toxicological investigations were performed in the biological and entomological samples of case#1 (hair, adipocere, brain, and pupae) and of case#2 (hair, bone, flies, and pupae) using liquid chromatography with high-resolution mass spectrometry and tandem mass spectrometry detection methods. In case#1, several drugs and metabolites were detected. In particular, the pupae analyses allowed the objectification of morphine administration, whereas morphine was only found in adipocere, but not in hair nor in brain. In case#2, the pupae analyses allowed the detection of three metabolites of quetiapine, and the flies analyses allowed the detection of valpromide, which was only detected in hair. In conclusion, the pupae and flies analyses in these two cases complemented the results obtained in the other alternative biological samples, which may guide hypotheses about the possible causes of death. Nevertheless, additional data and case reports would be of benefit to assess the value of entomotoxicology in routine forensic investigations.

Development and Validation of a GC-MS-EI Method to Determine α-PHP in Blood: Application to Samples Collected during Medico-Legal Autopsies

New psychoactive substances (NPSs) still represent an issue of great concern worldwide despite efforts made by national and international control systems to limit the spread of these substances. Alpha-pyrrolidinohexanophenone (α-PHP) is a fairly recent synthetic cathinone (the second largest group of monitored substances in Europe) with only a few published studies on the substance. Though there is a low incidence of NPS consumption in Portugal, a recent increase in apprehensions and detections in biological matrices of the substance was verified. An analytical methodology was developed and validated for determining and quantitating α-PHP in blood. Solid-phase extraction was employed for sample preparation (500 μL), which was further analyzed by gas chromatography--mass spectrometry-electron ionization in single-ion monitoring mode with cocaine-d3 as the internal standard. Method validation followed the guidelines of the American National Standards Institute/AAFS Standards Board (ANSI/ASB Standard 036). The procedure was linear between 10 and 1,000 ng/mL, with determination coefficients (r2) higher than 0.999. Carryover was not observed. A limit of detection of 5 ng/mL and a limit of quantitation of 10 ng/mL were achieved. Intraday and intermediate precision and bias assessment showed satisfactory results (coefficient of variation <17.7%; bias <11.6%), and extraction efficiency ranged from 98.5% to 103.3%. The stability of the substance was considered acceptable for at least 6 h at room temperature, 48 h in the autosampler and 21 days after five freeze/thaw cycles. The developed methodology was applied to 15 real samples from the Laboratory of Chemistry and Forensic Toxicology, Centre Branch of the National Institute of Legal Medicine and Forensic Sciences, Portugal, with drug concentrations ranging from 15 to 227 ng/mL. Available information for each case is also detailed in the present article.

New Psychoactive Substances: Major Groups, Laboratory Testing Challenges, Public Health Concerns, and Community-Based Solutions

Across communities worldwide, various new psychoactive substances (NPSs) continue to emerge, which worsens the challenges to global mental health, drug rules, and public health risks, as well as combats their usage. Specifically, the vast number of NPSs that are currently available, coupled with the rate at which new ones emerge worldwide, increasingly challenges both forensic and clinical testing strategies. The well-established NPS detection techniques include immunoassays, colorimetric tests, mass spectrometric techniques, chromatographic techniques, and hyphenated types. Nonetheless, mitigating drug abuse and NPS usage is achievable through extensive community-based initiatives, with increased focus on harm reduction. Clinically validated and reliable testing of NPS from human samples, along with community-driven solution, such as harm reduction, will be of great importance, especially in combating their prevalence and the use of other illicit synthetic substances. There is a need for continued literature synthesis to reiterate the importance of NPS, given the continuous emergence of illicit substances in the recent years. All these are discussed in this overview, as we performed another look into NPS, from differentiating the major groups and identifying with laboratory testing challenges to community-based initiatives.

A review of synthetic cathinones emerging in recent years (2019-2022)

Purpose

The emergence of novel psychoactive substances (NPS) has been being a continuous and evolving problem for more than a decade. Every year, dozens of new, previously unknown drugs appear on the illegal market, posing a significant threat to the health and lives of their users. Synthetic cathinones are one of the most numerous and widespread groups among NPS. The purpose of this work was to identify and summarize available data on newly emerging cathinones in very recent years.

Methods

Various online databases such as PubMed, Google Scholar, but also databases of government agencies including those involved in early warning systems, were used in search of reports on the identification of newly emerging synthetic cathinones. In addition, threads on various forums created by users of these drugs were searched for reports on the effects of these new substances.

Results

We have identified 29 synthetic cathinones that have been detected for the first time from early 2019 to mid-2022. We described their structures, known intoxication symptoms, detected concentrations in biological material in poisoning cases, as well as the countries and dates of their first appearance. Due to the lack of studies on the properties of the novel compounds, we compared data on the pharmacological profiles of the better-known synthetic cathinones with available information on the newly emerged ones. Some of these new agents already posed a threat, as the first cases of poisonings, including fatal ones, have been reported.

Conclusions

Most of the newly developed synthetic cathinones can be seen as analogs and replacements for once-popular compounds that have been declining in popularity as a result of legislative efforts. Although it appears that some of the newly emerging cathinones are not widely used, they may become more popular in the future and could become a significant threat to health and life. Therefore, it is important to continue developing early warning systems and identifying new compounds so that their widespread can be prevented.

Fatal cases involving new psychoactive substances and trends in analytical techniques

New psychoactive substances (NPS) are an emerging public health issue and deaths are commonly associated with polydrug abuse. Moreover, the number of new substances available is constantly increasing, causing intoxications in low doses, characteristics that impose to toxicology and forensic laboratories to keep routine methods up to date, with high detectability and constantly acquiring new analytical standards. Likewise, NPS metabolites and respective elimination pathways are usually unknown, making it difficult the detection and confirmation of the drug involved in the fatal case in an analytical routine. A literature search was performed on PubMed, Scopus and Web of Science databases for papers related to chromatographic analyses from fatal cases related to NPS use published from 2016 to 2021. A total of 96 papers were retrieved and reviewed in this study. Opioids, synthetic cathinones, phenethylamines/amphetamines and cannabinoids were the NPS classes most found in the fatal cases. In many cases, multiple compounds were detected in the biological samples, including prescription and other illegal drugs. Liquid chromatography-tandem mass spectrometry, an alternative to overcome the gas chromatography-mass spectrometry limitations for some compounds, was the analytical technique most used in the studies, and high resolution mass spectrometry was often applied to NPS metabolite investigation and structural characterization and identification of unknown compounds. Toxicological screening and quantitation methods need to be continuously updated to include new substances that are emerging on the drug market that can be fatal at very low doses.

Diclofenac Concentrations in Post-Mortem Specimens-Distribution, Case Reports, and Validated Method (UHPLC-QqQ-MS/MS) for Its Determination

The aim of the research was to establish a sensitive method for the quantification of diclofenac in postmortem samples. The developed method was applied in six cases: three fetuses in which the use of abortion pills by their mothers was suspected, one case of duodenal ulcer perforation, one case of traffic accident with fatal outcome, and one acute renal failure in which the distribution of diclofenac was examined. The analyses were performed using liquid-liquid extraction of postmortem samples and the quantification of diclofenac via ultra-high performance liquid chromatography, coupled with triple quadrupole tandem mass spectrometry. Gradient elution using a C18 column was applied. Electrospray ionization measurement in positive multiple reaction monitoring mode was used. Diclofenac-d4 was used as an internal standard. The validation parameters were as follows: lower limit of quantification: 0.5 ng/mL, linearity of calibration curve: 0.5-500 ng/mL, intra- and interday accuracies and precisions: not greater than 15%; recovery values: 72.0-102.2%, and matrix effect: 2.2-28.0%. The developed method enabled the determination of diclofenac in human postmortem biological fluids (blood, urine, vitreous humor, bile, and stomach content), tissues (placenta, kidney, liver, and heart), and in exhumated fetus bones, with high recovery, sensitivity, precision, and accuracy.

Trace Residue Identification, Characterization and Longitudinal Monitoring of the Novel Synthetic Opioid β-U10, from Discarded Drug Paraphernalia

Empirical data regarding dynamic alterations in illicit drug supply markets in response to the COVID-19 pandemic, including the potential for introduction of novel drug substances and/or increased poly-drug combination use at the 'street' level, i.e., directly proximal to the point of consumption, is currently lacking. Here, a high-throughput strategy employing ambient ionization-mass spectrometry is described for the trace residue identification, characterization and longitudinal monitoring of illicit drug substances found within >6,600 discarded drug paraphernalia (DDP) samples collected during a pilot study of an early warning system for illicit drug use in Melbourne, Australia from August 2020-February 2021, while significant COVID-19 lockdown conditions were imposed. The utility of this approach is demonstrated for the de novo identification and structural characterization of β-U10, a previously unreported naphthamide analogue within the 'U-series' of synthetic opioid drugs, including differentiation from its α-U10 isomer without need for sample preparation or chromatographic separation prior to analysis. Notably, β-U10 was observed with 23 other drug substances, most commonly in temporally distinct clusters with heroin, etizolam and diphenhydramine, and in a total of 182 different poly-drug combinations. Longitudinal monitoring of the number and weekly 'average signal intensity' (ASI) values of identified substances, developed here as a semi-quantitative proxy indicator of changes in availability, relative purity and compositions of street level drug samples, revealed that increases in the number of identifications and ASI for β-U10 and etizolam coincided with a 50% decrease in the number of positive detections and an order of magnitude decrease in the ASI for heroin.

Characteristics of fatal 'novel' synthetic opioid toxicity in Australia

BACKGROUND

Aims: To determine 1. The characteristics of all recorded cases of fatal drug poisoning involving novel synthetic opioids (NSOs) in Australia; 2. The toxicology of cases; and 3. The major autopsy findings.

METHODS

Review of all fatal poisonings related to NSOs in Australia 2000-2021 identified in the National Coronial Information System.

RESULTS

Thirty-one cases were identified, 96.8% due to unintentional drug toxicity. The mean age was 31.9 years and 87.1% were male. Only six were aged over forty. A history of substance use problems was documented in 80.6% and 58.1% had a history of injecting drug use. In 32.3% the final route of administration of a NSO was by non-injecting routes of administration. Ten NSOs were identified. Fentanyl analogues were present in 67.2%, most commonly furanylfenatyl (19.4%). Other NSO types were present in 39.7%, most commonly U-47700 (35.5%). Substances other than NSOs were present in 90.3%, most commonly benzodiazepines (67.7%) and other opioids (51.6%). A CNS depressant in addition to NSOs was present in 90.3%, and a new psychoactive substance other than a NSO in 25.8%. Pulmonary oedema was diagnosed in 82.6%, aspiration of vomitus in 30.4%, and acute bronchopneumonia in 17.4%.

CONCLUSIONS

Ten NSOs were identified. Case characteristics suggest a younger cohort whose profile is more typical of use of other NPS than of the established opioids. A large proportion used NSOs by non-injecting routes of administration.

Unexpected results found in larvae samples from two postmortem forensic cases

Purpose

In forensics, entomological specimens can be used as additional/alternative matrices to detect xenobiotics when human specimens are limited in their application. Despite some advantages over implementing putrefied human remains, most medico-legal laboratories do not include entomotoxicological procedures as routine analytical methods. We thus applied two authentic cases to evaluate necrophagous larvae’s potential as complementary matrices for toxicological analysis after extensive postmortem decomposition.

Methods

Larvae and postmortem human samples, including hair, stomach contents, pericardial fluid, liver, lung, and skeletal muscle, were collected at autopsy. Samples were analyzed by liquid chromatography–tandem mass spectrometry and liquid chromatography–quadrupole time-of-flight mass spectrometry for pharmaceutical substances, illicit drugs, and new psychoactive substances, including synthetic cannabinoids, benzodiazepines, new synthetic opioids, and stimulants.

Results

Nearly all substances detected in human specimens, including several benzodiazepines and synthetic cannabinoids, were also detected in larvae. Surprisingly, some drugs, including the new psychoactive substances EAM-2201 and U-47700, were found exclusively in larvae and hair. The benzodiazepine etizolam was detected only in liver, lungs, and stomach contents, possibly resulting from characteristic tissue distribution in humans and/or larvae.

Conclusions

Antemortem external hair contamination with synthetic cannabinoids from side-stream smoke and postmortem hair contamination with substances in putrefaction fluids can be supposed in these cases. Our findings suggest that supplementary information can indeed be gained from analyzing larvae additional to those human specimens that are typically used for toxicological analysis after extensive postmortem decomposition. Nevertheless, these results represent merely two cases, requiring in-depth studies to determine whether such findings can identify acute intoxications as possible causes of death.

Blood concentrations of new synthetic opioids

PURPOSE

Over the last decade, there has been a significant growth in the market and number of new psychoactive substances (NPS). One of the NPS groups that has grown rapidly in recent years, bringing a new set of problems, consists of new synthetic opioids. The extreme potency of these compounds poses a high risk of acute poisoning, as an overdose can cause respiratory depression. Most of the information regarding human pharmacokinetics of new opioids is based on toxicological case reports and the data on concentrations of new opioids in human blood are scarce. The interpretation of results usually requires a comparison to previously published cases; therefore, a referenced compilation of previously published concentration data would be useful.

METHODS

The data were collected by searching the PubMed and Scopus databases and by using the Google search engine. All the available data from articles and reports that measured new opioid concentrations in plasma, serum, or whole blood were included in the data analysis.

RESULTS

The presented tables list the observed concentrations in fatal and nonfatal cases involving 37 novel synthetic opioids.

CONCLUSIONS

Blood levels of new opioids are extremely difficult to interpret. Low blood concentrations of these substances do not rule out acute poisoning as their high potency creates a risk of respiratory depression even at low doses. Opioid tolerance, frequent presence of other drugs, and additional diseases make it impossible to define concentration ranges, especially the minimum fatal concentrations. This report provides quick access to the source articles quantifying novel synthetic opioids.

Alternative matrices in forensic toxicology: a critical review

Purpose

The use of alternative matrices in toxicological analyses has been on the rise in clinical and forensic settings. Specimens alternative to blood and urine are useful in providing additional information regarding drug exposure and analytical benefits. The goal of this paper is to present a critical review on the most recent literature regarding the application of six common alternative matrices, i.e., oral fluid, hair, sweat, meconium, breast milk and vitreous humor in forensic toxicology.

Methods

The recent literature have been searched and reviewed for the characteristics, advantages and limitations of oral fluid, hair, sweat, meconium, breast milk and vitreous humor and its applications in the analysis of traditional drugs of abuse and novel psychoactive substances (NPS).

Results

This paper outlines the properties of six biological matrices that have been used in forensic analyses, as alternatives to whole blood and urine specimens. Each of this matrix has benefits in regards to sampling, extraction, detection window, typical drug levels and other aspects. However, theses matrices have also limitations such as limited incorporation of drugs (according to physical–chemical properties), impossibility to correlate the concentrations for effects, low levels of xenobiotics and ultimately the need for more sensitive analysis. For more traditional drugs of abuse (e.g., cocaine and amphetamines), there are already data available on the detection in alternative matrices. However, data on the determination of emerging drugs such as the NPS in alternative biological matrices are more limited.

Conclusions

Alternative biological fluids are important specimens in forensic toxicology. These matrices have been increasingly reported over the years, and this dynamic will probably continue in the future, especially considering their inherent advantages and the possibility to be used when blood or urine are unavailable. However, one should be aware that these matrices have limitations and particular properties, and the findings obtained from the analysis of these specimens may vary according to the type of matrix. As a potential perspective in forensic toxicology, the topic of alternative matrices will be continuously explored, especially emphasizing NPS.

A 2017-2019 Update on Acute Intoxications and Fatalities from Illicit Fentanyl and Analogs

The aim of this review was to report the most recent cases of acute intoxication, fatalities and "driving under the influence" cases, involving illicit fentanyl and its newest analogs. When available, information on age, sex, circumstances of exposure, intoxication symptoms, cause of death (if applicable) and toxicology results from biological fluid testing was described. Scientific publications reporting fatalities or acute intoxications involving use of fentanyl derivatives were identified from PubMed, Scopus and institutional/governmental websites from January 2017 up to December 2019. The search terms, used alone and in combination, were as follows: fentanyl, street fentanyl, analogs, compounds, derivatives, abuse, fatality, fatalities, death, toxicity, intoxication and adverse effects. When considered relevant, reports not captured by the initial search but cited in other publications were also included. Of the 2890 sources initially found, only 44 were suitable for the review. Emergent data showed that the most common analogs detected in biological samples and seized materials are acetylfentanyl, acrylfentanyl, butyrfentanyl, carfentanil, cyclopropylfentanyl, fluorofentanyl, 4-fluorobutyrfentanyl, 4-fluoroisobutyrfentanyl, furanylfentanyl, 2-methoxyacetylfentanyl, 3-methylfentanyl and ocfentanil. These compounds were frequently administered in association with other illicit substances, medicinal drugs and/or alcohol; patients and the victims often had a previous history of drug abuse. The trend of fentanyl analogs is rapidly evolving with illicit market fluctuations. Since information about potency and lethal dosage are frequently unknown, it is important to identify the new trends for further investigation on therapeutic use, toxicity and fatal doses, and implement public health measures. Recently marketed fentanyl analogs such as crotonylfentanyl and valerylfentanyl were not involved in intoxications to date, but should be carefully monitored. Many intoxications and fatalities might have gone unnoticed, and research efforts should focus on metabolite identification studies and the implementation of updated and comprehensive analytical methods.

Spectroscopy as a useful tool for the identification of changes with time in post-mortem vitreous humor for forensic toxicology purposes

Vitreous humor (VH) is an alternative biological matrix with a great advantage of longer availability for analysis due to the lack of many enzymes. The use of VH in forensic toxicology may have an added benefit, however, this application requires rapid, simple, non-destructive, and relatively portable analytical analysis methods. These requirements may be met by Fourier transform infrared spectroscopy technique (FT-IR) equipped with attenuated total reflection accessory (ATR). FT-IR spectra of vitreous humor samples, deposited on glass slides, were collected and subsequent chemometric data analysis by means of Hierarchical Cluster Analysis and Principal Component Analysis was conducted. Differences between animal and human VH samples and human VH samples stored for diverse periods of time were detected. A kinetic study of changes in the VH composition up to 2 weeks showed the distinction of FT-IR spectra collected on the 1st and 14th day of storage. In addition, data obtained for the most recent human vitreous humor samples—collected 3 and 2 years before the study, presented successful discrimination of all time points studied. The method introduced was unable to detect mephedrone addition to VH in the concentration of 10 µg/cm3.

Graphic abstract

Perimortem Distribution of U-47700, Tramadol and their Main Metabolites in pigs Following Intravenous Administration

In spite of a decreasing number of new releases, New Synthetic Opioids (NSO) are gaining increasing importance in postmortem (PM) forensic toxicology. For the interpretation of analytical results, toxicokinetic (TK) data, e.g. on tissue distribution, are helpful. Concerning NSO, such data are usually not available due to the lack of controlled human studies. Hence, a controlled TK study using pigs was carried out and the tissue distribution of U-47700 and tramadol as reference was examined. Twelve pigs received an intravenous dose of 100 µg/kg body weight (BW) U-47700 or 1000 µg/kg BW tramadol, respectively. Eight hours after administration, the animals were put to death with T61. Relevant organs, body fluids and tissues were sampled. After homogenization and solid-phase extraction, quantification was performed applying standard addition and liquid chromatography-tandem mass spectrometry. At the time of death, the two parent compounds were determined in all analyzed specimens. Regarding U-47700, concentrations were highest in duodenum content, bile fluid and adipose tissue (AT). Concerning tramadol, next to bile fluid and duodenum content, highest concentrations were determined in the lung. Regarding the metabolites, N-desmethyl-U-47700 and O-desmethyltramadol (ODT) were detected in all analyzed specimens except for AT (ODT). Higher metabolite concentrations were found in specimens involved in metabolism. N-desmethyl-U-47700 showed much higher concentrations in routinely analyzed organs (lung, liver, kidney) than U-47700. To conclude, besides the routinely analyzed specimens in PM toxicology, AT, bile fluid and duodenum content could serve as alternative matrices for blood, urine or standard specimens such as kidney or liver. In case of U-47700, quantification of the main metabolite N-desmethyl-U-47700 is highly recommendable.

Overview of the major classes of new psychoactive substances, psychoactive effects, analytical determination and conformational analysis of selected illegal drugs

The misuse of psychoactive substances is attracting a great deal of attention from the general public. An increase use of psychoactive substances is observed among young people who do not have enough awareness of the harmful effects of these substances. Easy access to illicit drugs at low cost and lack of effective means of routine screening for new psychoactive substances (NPS) have contributed to the rapid increase in their use. New research and evidence suggest that drug use can cause a variety of adverse psychological and physiological effects on human health (anxiety, panic, paranoia, psychosis, and seizures). We describe different classes of these NPS drugs with emphasis on the methods used to identify them and the identification of their metabolites in biological specimens. This is the first review that thoroughly gives the literature on both natural and synthetic illegal drugs with old known data and very hot new topics and investigations, which enables the researcher to use it as a starting point in the literature exploration and planning of the own research. For the first time, the conformational analysis was done for selected illegal drugs, giving rise to the search of the biologically active conformations both theoretically and using lab experiments.

A Review of Synthetic Cathinone-Related Fatalities From 2017 to 2020

BACKGROUND

Synthetic cathinones (SCs) are designer analogs of the natural active principle of khat. Since their appearance on the black market in 2003, their popularity has increased annually, and they have become the most seized class of new psychoactive substances reported to the UNODC Early Warning Advisory system. The constant introduction of newly synthesized molecules makes this issue difficult to monitor. The authors reviewed the most recent SC-related fatalities worldwide to highlight new trends of consumption, reporting acute pharmacological and toxicological symptoms, scene investigations, analytical methods, and reported SC concentrations in diverse biological matrices.

METHODS

A literature search was performed using scientific databases such as PubMed, Scopus, Science Direct, Web of Science, and Research Gate to identify relevant scientific publications from 2017 to 2020. In addition, a search was conducted through the EU EWS.

RESULTS

From 2017 to 2020, 31 different SCs were identified in 75 reported fatal intoxications in the literature, alone or in combination with other substances. The most abused SCs were N-ethylpentylone, N-ethylhexedrone, and 4-chloromethcathinone. The EU EWS included less detail on 72 additional SC-related fatalities from 2017 to 2020.

CONCLUSIONS

New SCs continuously replace older natural and synthetic stimulant drugs, making determining the cause of death difficult. Analytical methods and high-performance mass spectrometry instruments are essential to detect the low concentrations of these potent new SCs. Little data are available on the pharmacology of these new drugs; the evaluation of toxicological antemortem and postmortem findings provides critical data on the drug's pharmacology and toxicology and for the interpretation of new SC cases.

Fatal intoxication with U-47700 in combination with other NPS (N-ethylhexedrone, adinazolam, 4-CIC, 4-CMC) confirmed by identification and quantification in autopsy specimens and evidences

Purpose

We present a case of fatal intoxication with U-47700 in combination with other NPS (N-ethylhexedrone, adinazolam, 4-chloro-N-isopropylcathinone (4-CIC), 4-chloromethcathinone (4-CMC) and sertraline) confirmed by identification and quantification in biological materials and evidences found at the scene in 2017 in Poland.

Methods

Blood and urine samples were extracted with ethyl acetate from alkaline medium (pH 9); powders/crystals were diluted with methanol. The analysis was carried out using ultra-high-performance liquid chromatography–tandem mass spectrometry. Validation criteria were evaluated for blood and urine at the concentrations of 10 and 100 ng/mL.

Results

The validation parameters of the method were within acceptable ranges. In the presented case, the determined concentrations of drugs were as follows, in blood: U-47700, 1470 ng/mL; N-ethylhexedrone, 58 ng/mL; adinazolam, 18 ng/mL; 4-CIC, 8.0 ng/mL; 4-CMC, 1.7 ng/mL; in urine: U-47700, 3940 ng/mL; N-ethylhexedrone, 147 ng/mL; adinazolam, 82 ng/mL; 4-CIC, 130 ng/mL; 4-CMC, 417 ng/mL. Sertraline (blood, 89 ng/mL; urine, 32 ng/mL) was also determined in both materials. The same substances were also found in 5 powders/crystals: U-47700 (12% by weight), N-ethylhexedrone (54%), adinazolam (14%), 4-CIC (23%), 4-CMC (26%). After 775 days of storage, biological samples at + 4 °C, the most stable substance was sertraline and the less, synthetic cathinones, especially 4-CIC and 4-CMC.

Conclusions

The described case of fatal intoxication with NPS presented postmortem concentrations of U-47700, 4-CMC, N-ethylhexedrone, adinazolam and 4-CIC for the first time in the literature. The paper also showed stability study of these substances stored at + 4 °C for 775 days.

Pyrrolidinyl Synthetic Cathinones α-PHP and 4F-α-PVP Metabolite Profiling Using Human Hepatocyte Incubations

For more than ten years, new synthetic cathinones (SCs) mimicking the effects of controlled cocaine-like stimulants have flooded the illegal drug market, causing numerous intoxications and fatalities. There are often no data on the pharmacokinetics of these substances when they first emerge onto the market. However, the detection of SC metabolites is often critical in order to prove consumption in clinical and forensic settings. In this research, the metabolite profile of two pyrrolidinyl SCs, α-pyrrolidinohexaphenone (α-PHP) and 4''-fluoro-α-pyrrolidinovalerophenone (4F-α-PVP), were characterized to identify optimal intake markers. Experiments were conducted using pooled human hepatocyte incubations followed by liquid chromatography-high-resolution tandem mass spectrometry and data-mining software. We suggest α-PHP dihydroxy-pyrrolidinyl, α-PHP hexanol, α-PHP 2'-keto-pyrrolidinyl-hexanol, and α-PHP 2'-keto-pyrrolidinyl as markers of α-PHP use, and 4F-α-PVP dihydroxy-pyrrolidinyl, 4F-α-PVP hexanol, 4F-α-PVP 2'-keto-pyrrolidinyl-hexanol, and 4F-α-PVP 2'-keto-pyrrolidinyl as markers of 4F-α-PVP use. These results represent the first data available on 4F-α-PVP metabolism. The metabolic fate of α-PHP was previously studied using human liver microsomes and urine samples from α-PHP users. We identified an additional major metabolite (α-PHP dihydroxy-pyrrolidinyl) that might be crucial for documenting exposure to α-PHP. Further experiments with suitable analytical standards, which are yet to be synthesized, and authentic specimens should be conducted to confirm these results.

Psychopharmacological characterization of an emerging drug of abuse, a synthetic opioid U-47700, in adult zebrafish

3,4-Dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) is a selective μ-opioid receptor agonist originally synthesized as a prospective analgesic drug. Several times more potent than morphine, U-47700 has high abuse potential and may cause clinical neurotoxicity, euphoria, respiratory depression and occasional mortality. U-47700 also evokes analgesia, sedation and euphoria-like states in both humans and rodents. Despite the growing use and abuse of U-47700, its psychopharmacological and toxicological profiles in vivo remain poorly understood. The zebrafish (Danio rerio) is rapidly becoming a popular aquatic model organism for central nervous system (CNS) disease modeling and drug discovery. Here, we examine acute (1, 5, 10, 25 and 50 mg/L for 20-min) and chronic (0.1, 0.5 and 1 mg/L for 14 days) effects of U-47700 in adult zebrafish. Overall, we found overt sedation evoked in fish by acute, and hyperlocomotion with an anxiolytic-like action by chronic, drug treatments. Acute treatment with 1 and 10 mg/L U-47700 also resulted in detectable amounts of this drug in the brain samples, supporting its permeability through the blood-brain barrier. Collectively, these findings emphasize complex dose- and treatment-dependent CNS effects of U-47700 following its acute and chronic administration. Our study also supports high sensitivity of zebrafish to U-47700, and suggests these aquatic models as promising in-vivo screens for probing potential CNS effects evoked by novel synthetic opioid drugs.

U-47700 and Its Analogs: Non-Fentanyl Synthetic Opioids Impacting the Recreational Drug Market

The recreational use of opioid drugs is a global threat to public health and safety. In particular, an epidemic of opioid overdose fatalities is being driven by illicitly manufactured fentanyl, while novel synthetic opioids (NSOs) are appearing on recreational drug markets as standalone products, adulterants in heroin, or ingredients in counterfeit drug preparations. Trans-3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) is a prime example of a non-fentanyl NSO that is associated with numerous intoxications and fatalities. Here, we review the medicinal chemistry, preclinical pharmacology, clandestine availability, methods for detection, and forensic toxicology of U-47700 and its analogs. An up-to-date summary of the human cases involving U-47700 intoxication and death are described. The evidence demonstrates that U-47700 is a potent μ-opioid receptor agonist, which poses a serious risk for overdosing and death. However, most analogs of U-47700 appear to be less potent and have been detected infrequently in forensic specimens. U-47700 represents a classic example of how chemical entities from the medicinal chemistry or patent literature can be diverted for use in recreational drug markets. Lessons learned from the experiences with U-47700 can inform scientists, clinicians, and policymakers who are involved with responding to the spread and impact of NSOs.

Recent bionalytical methods for the determination of new psychoactive substances in biological specimens

One of the problems associated with the consumption of new psychoactive substances is that in most scenarios of acute toxicity the possibility of quick clinical action may be impaired because many screening methods are not responsive to them, and laboratories are not able to keep pace with the appearance of new substances. For these reasons, developing and validating new analytical methods is mandatory in order to efficiently face those problems, allowing laboratories to be one step ahead. The goal of this work is to perform a critical review regarding bionalytical methods that can be used for the determination of new psychoactive substances (phenylethylamines, cathinones, synthetic cannabinoids, opioids, benzodiazepines, etc), particularly concerning sample preparation techniques and associated analytical methods.

Toward the Interpretation of Positive Testing for Fentanyl and Its Analogs in Real Hair Samples: Preliminary Considerations

The detection of new psychoactive substances (NPS) in hair has become extensively researched in recent years. Although most NPS fall into the classes of synthetic cannabinoids and designer cathinones, novel synthetic opioids (NSO) have appeared with increasing frequency in the illicit drug supply. While the detection of NSO in hair is now well documented, interpretation of results presents several controversial issues, as is quite common in hair analysis. In this study, an ultra-high-performance liquid chromatography-tandem mass spectrometry method able to detect 13 synthetic opioids (including fentanyl analogs) and metabolites in hair was applied to 293 real samples. Samples were collected in the USA between November 2016 and August 2018 from subjects who had reported heroin use in the past year or had already tested positive to hair testing for common opiates. The range, mean and median concentrations were calculated for each analyte, in order to draw a preliminary direction for a possible cut-off to discriminate between exposure to either low or high quantities of the drug. Over two-thirds (68%) of samples tested positive for fentanyl at concentrations between LOQ and 8600 pg/mg. The mean value was 382 pg/mg and the median was 95 pg/mg. The metabolites norfentanyl and 4-ANPP were also quantified and were found between LOQ and 320 pg/mg and between LOQ and 1400 pg/mg, respectively. The concentration ratios norfentanyl/fentanyl, 4-ANPP/fentanyl and norfentanyl/4-ANPP were also tested as potential markers of active use and to discriminate the intake of fentanyl from other analogs. The common occurrence of samples positive for multiple drugs may suggest that use is equally prevalent among consumers, which is not the case, as correlations based on quantitative results demonstrated. We believe this set of experimental observations provides a useful starting point for a wide discussion aimed to better understand positive hair testing for fentanyl and its analogs in hair samples.

Sex and Gender Differences in the Effects of Novel Psychoactive Substances

Sex and gender deeply affect the subjective effects and pharmaco-toxicological responses to drugs. Men are more likely than women to use almost all types of illicit drugs and to present to emergency departments for serious or fatal intoxications. However, women are just as likely as men to develop substance use disorders, and may be more susceptible to craving and relapse. Clinical and preclinical studies have shown important differences between males and females after administration of “classic” drugs of abuse (e.g., Δ9-tetrahydrocannabinol (THC), morphine, cocaine). This scenario has become enormously complicated in the last decade with the overbearing appearance of the new psychoactive substances (NPS) that have emerged as alternatives to regulated drugs. To date, more than 900 NPS have been identified, and can be catalogued in different pharmacological categories including synthetic cannabinoids, synthetic stimulants (cathinones and amphetamine-like), hallucinogenic phenethylamines, synthetic opioids (fentanyls and non-fentanyls), new benzodiazepines and dissociative anesthetics (i.e., methoxetamine and phencyclidine-derivatives). This work collects the little knowledge reached so far on the effects of NPS in male and female animal and human subjects, highlighting how much sex and gender differences in the effects of NPS has yet to be studied and understood.

Designer drugs: mechanism of action and adverse effects

Psychoactive substances with chemical structures or pharmacological profiles that are similar to traditional drugs of abuse continue to emerge on the recreational drug market. Internet vendors may at least temporarily sell these so-called designer drugs without adhering to legal statutes or facing legal consequences. Overall, the mechanism of action and adverse effects of designer drugs are similar to traditional drugs of abuse. Stimulants, such as amphetamines and cathinones, primarily interact with monoamine transporters and mostly induce sympathomimetic adverse effects. Agonism at μ-opioid receptors and γ-aminobutyric acid-A (GABA_A) or GABA_B receptors mediates the pharmacological effects of sedatives, which may induce cardiorespiratory depression. Dissociative designer drugs primarily act as N-methyl-d-aspartate receptor antagonists and pose similar health risks as the medically approved dissociative anesthetic ketamine. The cannabinoid type 1 (CB₁) receptor is thought to drive the psychoactive effects of synthetic cannabinoids, which are associated with a less desirable effect profile and more severe adverse effects compared with cannabis. Serotonergic 5-hydroxytryptamine-2A (5-HT_2A) receptors mediate alterations of perception and cognition that are induced by serotonergic psychedelics. Because of their novelty, designer drugs may remain undetected by routine drug screening, thus hampering evaluations of adverse effects. Intoxication reports suggest that several designer drugs are used concurrently, posing a high risk for severe adverse effects and even death.

New psychoactive substances: a review and updates

New psychoactive substances (NPS) are a heterogeneous group of substances. They are associated with a number of health and social harms on an individual and societal level. NPS toxicity and dependence syndromes are recognised in primary care, emergency departments, psychiatric inpatient and community care settings. One pragmatic classification system is to divide NPS into one of four groups: synthetic stimulants, synthetic cannabinoids, synthetic hallucinogens and synthetic depressants (which include synthetic opioids and benzodiazepines). We review these four classes of NPS, including their chemical structures, mechanism of action, modes of use, intended intoxicant effects, and their associated physical and mental health harms. The current challenges faced by laboratory testing for NPS are also explored, in the context of the diverse range of NPS currently available, rate of production and emergence of new substances, the different formulations, and methods of acquisition and distribution.