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.

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.

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.

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 β-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, β-OH, 4-OH and 4-OH-3-OMe were identified after hepatocyte incubation. β-OH was the major hydroxylated metabolite for all studied fentanyls, except for acetylfentanyl where 4-OH was more abundant. However, the ratio 4-OH/β-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.

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 β-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.

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.

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.

Stratification of alopecia areata reveals involvement of CD4 T cell populations and altered faecal microbiota

Alopecia areata (AA) is an immune-mediated disease that causes non-scarring hair loss. Autoreactive CD8 T cells are key pathogenic effectors in the skin, and AA has been associated both with atopy and with perturbations in intestinal homeostasis. This study aimed to investigate mechanisms driving AA by characterizing the circulating immunophenotype and faecal microbiome, and by stratifying AA to understand how identified signatures associated with heterogeneous clinical features of the condition. Flow cytometric analyses identified alterations in circulating B cells and CD4 T cells, while 16S sequencing identified changes in alpha and beta diversity in the faecal microbiome in AA. The proportions of transitional and naïve B cells were found to be elevated in AA, particularly in AA samples from individuals with >50% hair loss and those with comorbid atopy, which is commonly associated with extensive hair loss. Although significant changes in circulating CD8 T cells were not observed, we found significant changes in CD4+ populations. In individuals with <50% hair loss higher frequencies of CCR6+CD4 ("Th17") and CCR6+CXCR3+CD4 ("Th1/17") T cells were found. While microbial species richness was not altered, AA was associated with reduced evenness and Shannon diversity of the intestinal microbiota, again particularly in those with <50% hair loss. We have identified novel immunological and microbial signatures in individuals with alopecia areata. Surprisingly, these are associated with lower levels of hair loss, and may therefore provide a rationale for improved targeting of molecular therapeutics.

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.