Using in vitro receptor activity studies of synthetic cannabinoids to support the risk assessment of new psychoactive substances - A Swedish strategy to protect public health from harm.

In the past 15 years, close to 1000 of new psychoactive substances (NPS) have been reported in Europe and globally. At the time of identification, data on safety, toxicity and carcinogenic potential of many NPS are not available or very limited. To work more efficiently, a strategy and collaboration between the Public Health Agency of Sweden (PHAS) and the National Board of Forensic Medicine was established involving in vitro receptor activity assays to demonstrate neurological activity of NPS. This report summarizes the first results on the synthetic cannabinoid receptor agonists (SCRAs), and subsequent actions taken by PHAS. A total of 18 potential SCRAs were selected by PHAS for in vitro pharmacological characterization. 17 compounds could be acquired and investigated for their activity on the human cannabinoid-1 (CB1) receptors expressed together with the AequoScreen system in CHO-K1 cells. Dose-response curves were established using eight different concentrations in triplicates at three occasions with JWH-018 as reference. For the MDMB-4en-PINACA, MMB-022, ACHMINACA, ADB-BUTINACA, 5F-CUMYL-PeGACLONE, 5C-AKB48, NM-2201, 5F-CUMYL-PINACA, JWH-022, 5Cl-AB-PINACA, MPhP-2201, 5F-AKB57 the half maximal effective concentration values ranged from 2.2 nM (5F-CUMYL-PINACA) to 171 nM (MMB-022). EG-018 and 3,5-AB-CHMFUPPYCA were none-active. The results contributed to 14 of these compounds being scheduled as narcotics in Sweden. In conclusion, many of the emerging SCRAs are potent activators of the CB1 receptor in vitro, although some lack activity or are partial agonists. The new strategy proved useful when data on psychoactive effects of the SCRAs under investigation were not available or limited.

Circumstances, Postmortem Findings, Blood Concentrations and Metabolism in a Series of Methoxyacetylfentanyl-Related Deaths.

Methoxyacetylfentanyl is one of many fentanyl analogs available as new psychoactive substances. It have been encountered in both the European Union and the United States, and existing literature suggest that methoxyacetylfentanyl is around 3- to 5-fold less potent than fentanyl. The aim of the present work was to combine case information with blood concentrations and abundance of urinary metabolites to investigate the importance of these parameters for toxicological interpretation. Quantification of methoxyacetylfentanyl in femoral blood was performed by LC--MS-MS and urinary metabolites were analyzed by LC--QTOF-MS with and without hydrolysis with ß-glucuronidase/arylsulfatase. For confirmation of identified metabolites, methoxyacetylfentanyl was incubated with hepatocytes for up to 5 hours and analyzed with the same method as the urine samples. In eleven postmortem cases (27 to 41 years old and including one female) methoxyacetylfentanyl was reported in femoral blood. The cause of death was intoxication by methoxyacetylfentanyl alone or in combination with other drugs in all but one case, where death was attributed to acute complications of an underlying heart disease but with possible contribution from methoxyacetylfentanyl. In total, 27 urinary metabolites were found, including eight glucuronides. Major biotransformations were O-demethylation, dealkylation to form the nor-metabolite, mono- and dihydroxylations of the phenethyl moiety, as well as combinations thereof. The most abundant metabolites in hydrolyzed urine included O-desmethyl-, O-desmethyl-phenethyl-hydroxy-, O-desmethyl-phenethyl-hydroxymethoxy- and nor-methoxyacetylfentanyl. Differences in the abundance of methoxyacetylfentanyl and its major metabolites could be interpreted to indicate fatal intoxications in abstinent or chronic users. We postulate that urinary concentrations of methoxyacetylfentanyl and two metabolites, in combination with the methoxyacetylfentanyl concentration in femoral blood, might be good indicators of the time between administration and death as well as prior use.

Structure Elucidation of Urinary Metabolites of Fentanyl and Five Fentanyl Analogs using LC-QTOF-MS, Hepatocyte Incubations and Synthesized Reference Standards.

Fentanyl analogs constitute a particularly dangerous group of new psychoactive compounds responsible for many deaths around the world. Little is known about their metabolism, and studies utilizing liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) analysis of hepatocyte incubations and/or authentic urine samples do not allow for determination of the exact metabolite structures, especially when it comes to hydroxylated metabolites. In this study, seven motifs (2-, 3-, 4- and ß-OH as well as 3,4-diOH, 4-OH-3-OMe and 3-OH-4-OMe) of fentanyl and five fentanyl analogs, acetylfentanyl, acrylfentanyl, cyclopropylfentanyl, isobutyrylfentanyl and 4F-isobutyrylfentanyl were synthesized. The reference standards were analyzed by LC-QTOF-MS, which enabled identification of the major metabolites formed in hepatocyte incubations of the studied fentanyls. By comparison with our previous data sets, major urinary metabolites could tentatively be identified. For all analogs, ß-OH, 4-OH and 4-OH-3-OMe were identified after hepatocyte incubation. ß-OH was the major hydroxylated metabolite for all studied fentanyls, except for acetylfentanyl where 4-OH was more abundant. However, the ratio 4-OH/ß-OH was higher in urine samples than in hepatocyte incubations for all studied fentanyls. Also, 3-OH-4-OMe was not detected in any hepatocyte samples, indicating a clear preference for the 4-OH-3-OMe, which was also found to be more abundant in urine compared to hepatocytes. The patterns appear to be consistent across all studied fentanyls and could serve as a starting point in the development of methods and synthesis of reference standards of novel fentanyl analogs where nothing is known about the metabolism.

Activation of the µ-opioid receptor by alicyclic fentanyls: Changes from high potency full agonists to low potency partial agonists with increasing alicyclic substructure.

Fentanyl analogs represent an important group of new psychoactive substances and knowing their efficacy and potency might assist in interpreting observed concentrations. The potency of fentanyl analogs can be estimated from in vitro studies and can be used to establish structure-activity relationships. In this study, recombinant CHO-K1 cells (AequoScreen) expressing the human µ-opioid receptor were used to establish dose-response curves via luminescent analysis for cyclopropyl-, cyclobutyl-, cyclopentyl-, cyclohexyl-, and 2,2,3,3-tetramethylcyclopropylfentanyl (TMCPF), on three separate occasions, using eight different concentrations in an eight-fold serial dilution in triplicates starting at ~60 µM. Fentanyl was used as a full agonist reference while morphine and buprenorphine were included for comparison. Cyclopropylfentanyl (EC50 = 4.3 nM), cyclobutylfentanyl (EC50 = 6.2 nM), and cyclopentylfentanyl (EC50 = 13 nM) were full agonists slightly less potent than fentanyl (EC50 = 1.7 nM). Cyclohexylfentanyl (EC50 = 3.1 µM, efficacy 48%) and TMCPF (EC50 = 1.5 µM, efficacy 65%) were partial agonists less potent than morphine (EC50 = 430 nM). Based on the results, cyclopropyl-, cyclobutyl-, and cyclopentylfentanyl would be expected to induce intoxication or cause fatal poisonings at similar concentrations to fentanyl, while the toxic or fatal concentrations of cyclohexylfentanyl and TMCPF would be expected to be much higher.

In vitro characterization of new psychoactive substances at the µ-opioid, CB1, 5HT1A, and 5-HT2A receptors-On-target receptor potency and efficacy, and off-target effects.

New psychoactive substances (NPS) appear on the recreational market on a monthly basis, with unclear toxicology, resulting in an increasing number of fatalities. Identification of drug targets and potencies is crucial for understanding and treating intoxications and for scheduling processes. In this study 60 NPS and metabolites belonging to opioids, cannabinoids and serotonergic hallucinogens classes were screened for in vitro activation of the µ-opioid, CB1, 5-HT1A and 5-HT2A receptors using the AequoZen cell system. Fentanyl and NBOMe analogues were chosen for full dose-response characterization of the µ-opioid and 5-HT2A receptors, respectively. Most substances activated their corresponding target receptor. The most potent µ-opioid receptor agonists were 2-fluorofentanyl (EC50 = 1.0 nM), carfentanil (EC50 = 2.7 nM) and acrylfentanyl (EC50 = 2.8 nM) and in total a >1500-fold difference was seen among the tested compounds. Moreover, furanylfentanyl, 4-methoxybutyrylfentanyl and valerylfentanyl acted as partial agonists of the µ-receptor. On the 5-HT2A receptor, bromo-dragonfly showed the highest potency (EC50 = 0.05 nM, 400 times more potent than LSD), followed by most NBOMe compounds with EC50 values ranging from 0.11 nM (for 25N-NBOMe) to 1.3 nM (for 25T4-NBOMe)). Off-target activation of the µ-opioid receptor was identified for piperazines, phenethylamines (in particular NBOMe and 2C compounds) and tryptamines. Moreover, the synthetic cannabinoid metabolite 3-carboxy indole PB-22 activated the 5-HT2A receptor. Bromo-dragonfly was the only compound that activated all four receptors. These results highlight the possible interplay of known and unknown NPS targets and unveil its complexity. Moreover, the detailed, quantitative information presented facilitates our further understanding of NPS toxicology.

5F-MDMB-PICA metabolite identification and cannabinoid receptor activity.

According to the European Monitoring Center for Drugs and Drug Addiction (EMCDDA), there were 179 different synthetic cannabinoids reported as of 2017. In the USA, 5F-MDMB-PINACA, or 5F-ADB, accounted for 28% of cannabinoid seizures 2016-2018. The synthetic cannabinoid, 5F-MDMB-PICA, is structurally similar to 5F-MDMB-PINACA with an indole group replacing the indazole. Limited data exist from in vivo or in vitro metabolic studies of these synthetic cannabinoids, so potential metabolites to identify use may be missed. The goals of this study were to (a) investigate 5F-MDMB-PICA and 5F-MDMB-PINACA in vitro metabolism utilizing human hepatocytes; (b) to verify in vitro metabolites by analyzing authentic case specimens; and (c) to identify the potency and efficacy of 5F-MDMB-PICA and 5F-MDMB-PINACA by examining activity at the CB1 receptor. Biotransformations found in this study included phase I transformations and phase II transformations. A total of 22 5F-MDMB-PICA metabolites (A1 to A22) were identified. From hepatocyte incubations and urine samples, 21 metabolites (B1 to B21) were identified with 3 compounds unique to urine specimens for 5F-MDMB-PINACA. Phase II glucuronides were identified in 5F-MDMB-PICA (n = 3) and 5F-MDMB-PINACA (n = 5). For both compounds, ester hydrolysis and ester hydrolysis in combination with oxidative defluorination were the most prevalent metabolites produced in vitro. Additionally, the conversion of ester hydrolysis with oxidative defluorination to pentanoic acid for the first time was identified for 5F-MDMB-PICA. Therefore, these metabolites would be potentially good biomarkers for screening urine of suspected intoxication of 5F-MDMB-PICA or 5F-MDMB-PINACA. Both 5F-MDMB-PICA and 5F-MDMB-PINACA were acting as full agonists at the CB1 receptor with higher efficacy and similar potency as JWH-018.

Metabolite Profiling of Ortho-, Meta- and Para-Fluorofentanyl by Hepatocytes and High-Resolution Mass Spectrometry.

New psychoactive substances are emerging on the illegal drug market. Synthetic opioids including fentanyl analogues are of special concern due to their high potency. This indicates the possibility of low drug concentrations in vivo and calls for sensitive analytical methods and identification of the most appropriate analytical targets. In this study the in vitro metabolism of ortho-, meta- and para-fluorofentanyl, three fluorinated derivatives of fentanyl, has been investigated using human hepatocytes and compared to the results from an authentic human urine sample. Based on knowledge on the metabolism of similar fentanyl analogues N-dealkylation and hydroxylation was hypothesized to be the most central pathways. The three fluorofentanyl isomers were incubated with pooled human hepatocytes at 1, 3 and 5 h. Liquid chromatography quadrupole time of flight mass spectrometry operating in data-dependent mode was used to analyse the hepatocyte samples, as well as the hydrolysed and non-hydrolysed authentic urine sample. Data were analysed by a targeted approach with a database of potential metabolites. The major metabolite formed in vitro was the N-dealkylation product norfluorofentanyl. In addition various hydroxylated metabolites, a N-oxide, dihydrodiol metabolites and a hydroxymethoxy metabolite were found. In total, 14 different metabolites were identified for each fluorofentanyl isomer. In the authentic urine sample, three metabolites were detected in addition to the ortho-fluorofentanyl parent compound, with hydroxymethoxy metabolite having the highest abundance followed by norfluorofentanyl and a metabolite hydroxylated on the ethylphenyl ring. This in vitro study showed that the metabolic pattern for ortho-, meta-, and para-fluorofentanyl was close to those previously reported for other fentanyl analogues. We suggest that the hydroxymethoxy metabolite and the metabolite hydroxylated on the ethylphenyl ring should be the metabolites primarily investigated in further studies to determine the most appropriate marker for intake of fluorofentanyl derivatives in urine drug screening for human subjects.

Biotransformation of the New Synthetic Cannabinoid with an Alkene, MDMB-4en-PINACA, by Human Hepatocytes, Human Liver Microsomes, and Human Urine and Blood.

Although at a slower rate, new psychoactive substances continue to appear on the illicit drug market, challenging their detection in biological specimens by forensic and clinical toxicologists. Here, we report in vitro and in vivo metabolism of a new synthetic cannabinoid, methyl 3,3-dimethyl-2-[1-(pent-4-en-1-yl)-1H-indazole-3-carboxamido] butanoate (MDMB-4en-PINACA). This is the first report on metabolism of a synthetic cannabinoid with an alkene functional group at the alkyl side chain. MDMB-4en-PINACA was incubated with both human hepatocytes and human liver microsomes (HLM) for up to 5 h and 1 h, respectively. The samples were analyzed by liquid chromatography-quadrupole time-of-flight mass spectrometry. An authentic human urine and a corresponding blood sample were analyzed to confirm the in vitro metabolites. A total of 32 metabolites were detected, of which 11 metabolites were detected in hepatocyte samples, 31 in HLM, 2 in urine, and 1 in blood. Analysis of the metabolites revealed that the main metabolic pathway of the terminal alkene group of the pentenyl side chain is dihydrodiol formation, most likely via epoxidation. The majority of the metabolites were generated from ester hydrolysis and/or dihydrodiol formation with further hydroxylation and/or dehydrogenation. Two most abundant metabolites in hepatocyte incubation samples, M8 (ester hydrolysis and dihydrodiol) and M30 (ester hydrolysis), coincided the two detected urinary metabolites. Based on the results, M8 and M30 are proposed to be appropriate urinary markers for MDMB-4en-PINACA intake for screening, while the inclusion of the parent drug itself and M29 (hydroxylation) may be useful for confirmation purposes.

LC-QTOF-MS Identification of Major Urinary Cyclopropylfentanyl Metabolites Using Synthesized Standards.

Cyclopropylfentanyl is a fentanyl analog implicated in 78 deaths in Europe and over 100 deaths in the United States, but toxicological information including metabolism data about this drug is scarce. The aim of this study was to provide the exact structure of abundant and unique metabolites of cyclopropylfentanyl along with synthesis routes. In this study, metabolites were identified in 13 post-mortem urine samples using liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Samples were analyzed with and without enzymatic hydrolysis, and seven potential metabolites were synthesized in-house to provide the identity of major metabolites. Cyclopropylfentanyl was detected in all samples, and the most abundant metabolite was norcyclopropylfentanyl (M1) that was detected in 12 out of 13 samples. Reference materials were synthesized (synthesis routes provided) to identify the exact structure of the major metabolites 4-hydroxyphenethyl cyclopropylfentanyl (M8), 3,4-dihydroxyphenethyl cyclopropylfentanyl (M5) and 4-hydroxy-3-methoxyphenethyl cyclopropylfentanyl (M9). These metabolites are suitable urinary markers of cyclopropylfentanyl intake as they are unique and detected in a majority of hydrolyzed urine samples. Minor metabolites included two quinone metabolites (M6 and M7), not previously reported for fentanyl analogs. Interestingly, with the exception of norcyclopropylfentanyl (M1), the metabolites appeared to be between 40% and 90% conjugated in urine. In total, 11 metabolites of cyclopropylfentanyl were identified, including most metabolites previously reported after hepatocyte incubation.

Correlations between metabolism and structural elements of the alicyclic fentanyl analogs cyclopropyl fentanyl, cyclobutyl fentanyl, cyclopentyl fentanyl, cyclohexyl fentanyl and 2,2,3,3-tetramethylcyclopropyl fentanyl studied by human hepatocytes and LC-QTOF-MS.

Recently, a number of fentanyl analogs have been implicated in overdose deaths in Europe and in the US. So far, little is known of the molecular behavior of the structurally related subgroup; the alicyclic fentanyls. In this study, reference standards of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and 2,2,3,3-tetramethylcyclopropyl fentanyl (TMCPF) at a final concentration of 5 µM were incubated with cryopreserved human hepatocytes (1 × 106 cells/mL) for 0, 1, 3 and 5 h. The metabolites formed were identified by liquid chromatography-quadrupole time-of-flight mass spectrometry analysis. The most abundant biotransformation found was N-dealkylation (formation of normetabolites) and oxidation of the alicyclic rings. As ring size increased, the significance of N-dealkylation decreased in favor of alicyclic ring oxidation. An example of this was cyclopropyl fentanyl, with a three-carbon ring, whose normetabolite covered 82% of the total metabolic peak area and no oxidation of the alicyclic ring was observed. In contrast, TMCPF, with a seven-carbon ring structure, rendered as much as 85% of its metabolites oxidized on the alicyclic ring. Other biotransformations found included oxidation of the piperidine ethyl moiety and/or the phenethyl substructure, glucuronidation as well as amide hydrolysis to form metabolites identical to despropionyl fentanyl. Taken together, this study provides a base for understanding the metabolism of a number of structurally related fentanyl analogs formed upon intake.

Metabolism study for CUMYL-4CN-BINACA in human hepatocytes and authentic urine specimens: Free cyanide is formed during the main metabolic pathway.

To further elucidate the metabolism of CUMYL-4CN-BINACA, a new synthetic cannabinoid with a cyano group, and to evaluate biomarkers, we incubated the substance in human hepatocytes and analysed 9 authentic urine specimens. We also quantified CUMYL-4CN-BINACA and cyanide in blood and provide comprehensive data on the 7 autopsy cases, 5 of them determined CUMYL-4CN-BINACA intoxications. For metabolite elucidation, CUMYL-4CN-BINACA was incubated with pooled human hepatocytes for up to 5 hours, urine samples were analysed with and without enzymatic hydrolysis. Data was acquired in data-dependent mode by ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) with an Agilent 6550 QTOF. For quantitative analysis of CUMYL-4CN-BINACA, blood samples were precipitated and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cyanide was determined by gas chromatography-headspace-nitrogen phosphorus detection (GC-headspace-NPD). CUMYL-4CN-BINACA was metabolised via CYP450-mediated hydroxylation at 4-butyl position generating a cyanohydrin (M12), which releases free cyanide to form an aldehyde intermediate and eventually generates 4-hydroxybutyl CUMYL-BINACA (M11) and CUMYL-BINACA butanoic acid (M10). Other minor metabolites were produced by hydroxylation, dihydroxylation, N-dealkylation, and dihydrodiol formation; glucuronidation was observed. One urine sample showed high intensities of M10 and a wide variety of metabolites; the other samples contained fewer metabolites in low abundance and 1 sample showed no metabolites. CUMYL-4CN-BINACA blood concentrations ranged from 0.1 to 8.3 ng/g showing an overlap between fatal and non-fatal concentrations. One blood sample contained 0.36 µg/g cyanide. Release of free cyanide during metabolism is worrying as it might induce liver toxicity. As suggested earlier, CUMYL-BINACA butanoic acid is the most abundant biomarker in urine, but monitoring of additional metabolites or, even better, analysis for the parent in blood is recommended.

Poststroke Physical Activity Levels No Higher in Rehabilitation than in the Acute Hospital.

BACKGROUND: Returning to physical activity is a common goal for stroke survivors undergoing rehabilitation, and higher levels of activity have been linked to better gait and greater independence in activities of daily living. Our aim was to determine if inpatient rehabilitation settings promoted higher levels of physical activity in stroke survivors than an acute stroke unit setting. METHODS: Stroke survivors were recruited from the inpatient rehabilitation wards of 4 different hospitals in southern Sweden and from the acute stroke unit at Karolinska University Hospital in Stockholm. Participants were observed for 1 minute every 10 minutes from 8:00 a.m. to 5:00 p.m. At each observation, the person's highest level of physical activity, location, and other people present were recorded. RESULTS: We collected data from 190 stroke survivors (104 rehabilitation, 86 acute). Contrary to our hypothesis, there was no significant difference between the groups in the amount of time spent in moderate-to-high physical activity (rehabilitation median 24%, acute median 23%; adjusted P = .74). Compared to those in the acute setting, participants in the rehabilitation setting spent less time lying in bed, more time sitting supported out of bed, less time in their bedroom, and more time with a therapist (all adjusted P < .001). CONCLUSION: In the context of stroke, the inpatient rehabilitation environment does not appear to promote higher levels of physical activity than the acute hospital environment.