Metabolism of ADB-FUBIATA in zebrafish and pooled human liver microsomes investigated by liquid chromatography-high-resolution mass spectrometry

RATIONALE

ADB-FUBIATA is one of the most recently identified new psychoactive substance (NPS) of synthetic cannabinoids. The co-use of in vitro (human liver microsomes) and in vivo (zebrafish) models offers abundant metabolites and may give a deep insight into the metabolism of NPS.

METHODS

In vivo and in vitro metabolic studies of new synthetic cannabinoid ADB-FUBIATA were carried out using zebrafish and pooled human liver microsome models. Metabilites were structurally characterized by liquid chromatography-high-resolution mass spectrometry.

RESULTS

In total, 18 metabolites were discovered and identified in the pooled human liver microsomes and zebrafish, including seventeen phase I metabolites and one phase II metabolite. The main metabolic pathways of ADB-FUBIATA were hydroxylation, dehydrogenation, N-dealkylation, amide hydrolysis, glucuronidation, and combination thereof.

CONCLUSION

Hydroxylated metabolites can be recommended as metabolic markers for ADB-FUBIATA because of the structural characteristics and high intensity. These metabolism characteristics of ADB-FUBIATA were useful for its further forensic or clinical related investigations.

Narrative Review of the Pharmacodynamics, Pharmacokinetics, and Toxicities of Illicit Synthetic Cannabinoid Receptor Agonists

BACKGROUND

Synthetic cannabinoid receptor agonists (SCRAs) are the most diverse class of new psychoactive substances worldwide, with approximately 300 unique SCRAs identified to date. While the use of this class of drug is not particularly prevalent, SCRAs are associated with several deaths every year due to their severe toxicity.

METHODS

A thorough examination of the literature identified 15 new SCRAs with a significant clinical impact between 2015 and 2021.

RESULTS

These 15 SCRAs have been implicated in 154 hospitalizations and 209 deaths across the US, Europe, Asia, and Australasia during this time period.

CONCLUSION

This narrative review provides pharmacodynamic, pharmacokinetic, and toxicologic data for SCRAs as a drug class, including an in-depth review of known pharmacological properties of 15 recently identified and emerging SCRAs for the benefit of researchers, policy makers, and clinicians who wish to be informed of developments in this field.

A study of major cannabinoids via Raman spectroscopy and density functional theory

Cannabinoids, a class of molecules specific to the cannabis plant, are some of the most relevant molecules under study today due to their widespread use and varying legal status. Here, we present Raman spectra of a series of eleven cannabinoids and compare them to simulated spectra from density functional theory computations. The studied cannabinoids include three cannabinoid acids (Δ9-THC acid, CBD acid, and CBG acid) and eight neutral ones (Δ9-THC, CBD, CBG, CBDVA, CBDV, Δ8-THC, CBN and CBC). All cannabinoids have been isolated from cannabis plant gown at the University of Mississippi. The data presented in this work represents the most resolved experimental and highest-level simulated spectra available to date for each cannabinoid. All cannabinoids displayed higher peak separation in the experimental spectra than CBGA, which is most likely attributable to physical composition of the samples. The overall agreement between the experimental and simulated spectra is good, however for certain vibrational modes, especially those in the -OH stretching region, deviations are observed due to hydrogen bonding, suggesting that the OH stretching region is a good probe for decarboxylation reactions in these and related species.

Human phase-I metabolism and prevalence of two synthetic cannabinoids bearing an ethyl ester moiety: 5F-EDMB-PICA and EDMB-PINACA

Around 2017, with the appearance of 5F-EDMB-PINACA, synthetic cannabinoids (SCs) carrying an ethyl ester moiety at the linked group started spreading on the market of new psychoactive substances (NPS). In 2020 and 2021, the indole analog of 5F-EDMB-PINACA (5F-EDMB-PICA) and the non-fluorinated analog of this compound (EDMB-PINACA) were analytically characterized. Here, we present suitable urinary markers to prove the consumption of these two ethyl analogs. Ten authentic urine samples for each compound were analyzed by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-qToF-MS). Anticipated phase-I metabolites detected in urine samples were confirmed in vitro by applying a pooled human liver microsomes (pHLM) assay. Prevalence data were obtained from urines collected for abstinence control and submitted to a screening method for SC metabolites. Ten phase-I metabolites of 5F-EDMB-PICA and 18 of EDMB-PINACA were detected by LC-qToF-MS analysis of authentic urine specimens. The main in-vivo metabolites were built by ester hydrolysis, often coupled to further metabolic processes. Investigation of phase-I biotransformation led to the identification of ester hydrolysis, monohydroxylation, and defluorination products as the most suitable urinary biomarkers for 5F-EDMB-PICA. Metabolites formed by ester hydrolysis coupled to ketone formation and by monohydroxylation are suggested for the detection of EDMB-PINACA. From October 1, 2020 to February 1, 2022, among positive urine samples, 5.4% and 10.1% tested positive 5F-EDMB-PICA and EDMB-PINACA, respectively. Due to common metabolites shared among structurally related SCs, the unequivocal detection of their consumption remains challenging for forensic laboratories and requires sensitive methods to monitor multiple metabolites, ideally including highly specific species.

Synthetic Cannabinoids: A Pharmacological and Toxicological Overview

Synthetic cannabinoids (SCs) are a chemically diverse group of new psychoactive substances (NPSs) that target the endocannabinoid system, triggering a plethora of actions (e.g., elevated mood sensation, relaxation, appetite stimulation) that resemble, but are more intense than, those induced by cannabis. Although some of these effects have been explored for therapeutic applications, anticipated stronger psychoactive effects than cannabis and reduced risk perception have increased the recreational use of SCs, which have dominated the NPS market in the United States and Europe over the past decade. However, rising SC-related intoxications and deaths represent a major public health concern and embody a major challenge for policy makers. Here, we review the pharmacology and toxicology of SCs. A thorough characterization of SCs' pharmacodynamics and toxicodynamics is important to better understand the main mechanisms underlying acute and chronic effects of SCs, interpret the clinical/pathological findings related to SC use, and improve SC risk awareness.

An Update on the Implications of New Psychoactive Substances in Public Health

The emergence of new psychoactive substances has earned a great deal of attention, and several reports of acute poisoning and deaths have been issued involving, for instance, synthetic opiates. In recent years, there have been profound alterations in the legislation concerning consumption, marketing, and synthesis of these compounds; rapid alert systems have also been subject to changes, and new substances and new markets, mainly through the internet, have appeared. Their effects and how they originate in consumers are still mostly unknown, primarily in what concerns chronic toxicity. This review intends to provide a detailed description of these substances from the point of view of consumption, toxicokinetics, and health consequences, including case reports on intoxications in order to help researchers and public health agents working daily in this area.

Metabolism of third generation synthetic cannabinoids using zebrafish larvae

Synthetic cannabinoids are the second largest group of new psychoactive substances reported by the United Nations Office on Drugs and Crime in the last decade and case reports bring attention to its high potency effects and its severe toxicity, including fatalities. Moreover, synthetic cannabinoids are usually entirely metabolized and metabolic pathways for many new generation synthetic cannabinoids are still unknown. In this study, the metabolism of five third generation synthetic cannabinoids was evaluated using zebrafish (Danio rerio) larvae as 24-h in vivo model studied within 5 days after fertilization. The studied synthetic cannabinoids were MMB-CHMICA, ADB-CHMICA, ADB-CHMINACA, MDMB-CHMCZCA, and NNL-3, and the respective metabolites were identified by liquid chromatography-high resolution tandem mass spectrometry. Eleven, six, fourteen, eleven, and four metabolites were identified for MMB-CHMICA, ADB-CHMICA, ADB-CHMINACA, MDMB-CHMCZCA, and NNL-3, respectively, and metabolic pathways have been proposed. The use of zebrafish larvae, with a high degree of physiological and genetic homology to humans, is an emerging tool very useful for the identification of metabolic pathways of psychoactive substances. Results obtained in this study compared well with metabolites obtained previously for the same target molecules or structural analogous after in vitro incubation with human or rat hepatocytes. Thus, potential biomarkers for the evaluated compounds are the O-demethylated metabolite for MMB-CHMICA; the oxidative deamination to hydroxyl metabolite for ADB-CHMICA; hydroxyl metabolites at cyclohexylmethyl, tert-butyl, and indazole moieties for ADB-CHMINACA; hydroxyl metabolites at carbazole core, tert-butyl, or cyclohexylmethyl tail moieties for MDMB-CHMCZCA; and amide hydrolyzed, defluorinated, and dihydroxilated metabolite for NNL-3.

Synthetic cannabinoid receptor agonists and their human metabolites in sewage water: Stability assessment and identification of transformation products

Since their first appearance in 2008, synthetic cannabinoid receptor agonists (SCRAs) remain the most popular new psychoactive substances (NPS) in the EU. Following consumption, these drugs and their metabolites are urinary excreted and enter the sewage system enabling the application of wastewater-based epidemiology (WBE). Knowing the fate of target analytes in sewage water is essential for successful application of WBE. This study investigates the stability of several chemically diverse SCRAs and selected human metabolites under sewage conditions utilizing a combination of liquid chromatography-tandem mass spectrometry and high-resolution mass spectrometry (HRMS). Target analytes included SCRAs with indole (5F-PB-22, PB-22 pentanoic acid), indazole (AMB-FUBINACA, 5F-ADB, 5F-ADB dimethylbutanoic acid), carbazole (MDMB-CHMCZCA, EG-018), and γ-carboline (Cumyl-PeGaClone) chemical core structures representing most of the basic core structures that have occurred up to now. Stability tests were performed using wastewater effluent containing 5% activated sludge as inoculum to monitor degradation processes and formation of transformation products (TPs). The majority of investigated SCRAs, excluding the selected human metabolites, was recalcitrant to microbial degradation in sewage systems over a period of 29 days. Their stability was rather controlled by physico-chemical processes like sorption and hydrolysis. Considering a typical hydraulic in-sewer retention time of 24 h, the concentration of AMB-FUBINACA decreased by 90% thus representing the most unstable SCRA investigated in this study. Among the 10 newly identified TPs, three could be considered as relevant markers and should be included into future WBE studies to gain further insight into use and prevalence of SCRAs on the drug market.

New synthetic cannabinoids carrying a cyclobutyl methyl side chain: Human Phase I metabolism and data on human cannabinoid receptor 1 binding and activation of Cumyl-CBMICA and Cumyl-CBMINACA

Synthetic cannabinoids (SCs) represent a large group of new psychoactive substances (NPS), sustaining a high prevalence on the drug market since their first detection in 2008. Cumyl-CBMICA and Cumyl-CBMINACA, the first representatives of a new subclass of SCs characterized by a cyclobutyl methyl (CBM) moiety, were identified in July 2019 and February 2020. This work aimed at evaluating basic pharmacological characteristics and human Phase I metabolism of these compounds. Human Phase I metabolites were tentatively identified by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QToF-MS) of urine samples and confirmed by a pooled human liver microsome (pHLM) assay. The basic pharmacological evaluation was performed by applying a competitive ligand binding assay and a functional activation assay (GTPγS) using cell membranes carrying the human cannabinoid receptor 1 (hCB₁ ). Investigation of the human Phase I metabolism resulted in the identification of specific urinary markers built by monohydroxylation or dihydroxylation. Although Cumyl-CBMICA was primarily hydroxylated at the indole ring, hydroxylation of Cumyl-CBMINACA mainly occurred at the CBM moiety. Both substances acted as agonists at the hCB₁ receptor, although substantial differences could be observed. Cumyl-CBMINACA showed higher binding affinity (K_i  = 1.32 vs. 29.3 nM), potency (EC₅₀  = 55.4 vs. 497 nM), and efficacy (E_max  = 207% vs. 168%) than its indole counterpart Cumyl-CBMICA. This study confirms that substitution of an indole by an indazole core tends to increase in vitro potency, which is potentially reflected by higher in vivo potency. The emergence and disappearance of SCs distributed via online shops carrying a CBM moiety once more demonstrate the "cat-and-mouse" game between manufacturers and legislation.

A Systematic Study of the In Vitro Pharmacokinetics and Estimated Human In Vivo Clearance of Indole and Indazole-3-Carboxamide Synthetic Cannabinoid Receptor Agonists Detected on the Illicit Drug Market

In vitro pharmacokinetic studies were conducted on enantiomer pairs of twelve valinate or tert-leucinate indole and indazole-3-carboxamide synthetic cannabinoid receptor agonists (SCRAs) detected on the illicit drug market to investigate their physicochemical parameters and structure-metabolism relationships (SMRs). Experimentally derived Log D_7.4 ranged from 2.81 (AB-FUBINACA) to 4.95 (MDMB-4en-PINACA) and all SCRAs tested were highly protein bound, ranging from 88.9 ± 0.49% ((R)-4F-MDMB-BINACA) to 99.5 ± 0.08% ((S)-MDMB-FUBINACA). Most tested SCRAs were cleared rapidly in vitro in pooled human liver microsomes (pHLM) and pooled cryopreserved human hepatocytes (pHHeps). Intrinsic clearance (CL_int) ranged from 13.7 ± 4.06 ((R)-AB-FUBINACA) to 2944 ± 95.9 mL min⁻¹ kg⁻¹ ((S)-AMB-FUBINACA) in pHLM, and from 110 ± 34.5 ((S)-AB-FUBINACA) to 3216 ± 607 mL min⁻¹ kg⁻¹ ((S)-AMB-FUBINACA) in pHHeps. Predicted Human in vivo hepatic clearance (CL_H) ranged from 0.34 ± 0.09 ((S)-AB-FUBINACA) to 17.79 ± 0.20 mL min⁻¹ kg⁻¹ ((S)-5F-AMB-PINACA) in pHLM and 1.39 ± 0.27 ((S)-MDMB-FUBINACA) to 18.25 ± 0.12 mL min⁻¹ kg⁻¹ ((S)-5F-AMB-PINACA) in pHHeps. Valinate and tert-leucinate indole and indazole-3-carboxamide SCRAs are often rapidly metabolised in vitro but are highly protein bound in vivo and therefore predicted in vivo CL_H is much slower than CL_int. This is likely to give rise to longer detection windows of these substances and their metabolites in urine, possibly as a result of accumulation of parent drug in lipid-rich tissues, with redistribution into the circulatory system and subsequent metabolism.

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 transnational perspective on the evolution of the synthetic cannabinoid receptor agonists market: Comparing prison and general populations

The synthetic cannabinoid receptor agonist (SCRA) market is transnational, and the availability of individual SCRAs changes regularly in response to national and international legislative controls. This generates a cyclic pattern and near constant evolution of SCRA compounds. This study reports toxicology-based and/or seized sample-based prevalence data relating to SCRA use in prisons from Germany, the United Kingdom (UK; Scotland and Wales), and the United States (US), representing 4427 individual test results. The study examines SCRA detections in prisons from July 2018 to September 2020, and where possible, prison-based data are compared with SCRA prevalence data in the wider population. The relative influence of Chinese, other international, and national drug legislation on the prevalence of individual SCRAs in prisons is also considered. tert-Leucinate- and valinate-indole- and indazole-3-carboxamides were the most common SCRA detections, and MDMB-4en-PINACA was one of the most commonly detected SCRAs in all jurisdictions by September 2020. However, despite there being a global production and supply market, there were notable regional differences. Analog controls in German and US legislation may have led to increased compound diversity that is not reflected in the UK which has both analog controls and a blanket ban on psychoactive substances. While there were regional differences, SCRA prevalence in prisons closely aligned with the SCRAs detected on the local market, demonstrating that SCRA (and possibly other NPS) monitoring programs in prisons can act as early warning systems for the wider population in that given jurisdiction.

Comparison of in vitro and in vivo models for the elucidation of metabolic patterns of 7-azaindole-derived synthetic cannabinoids exemplified using cumyl-5F-P7AICA

Due to the dynamic market involving synthetic cannabinoids (SCs), the determination of analytical targets is challenging in clinical and forensic toxicology. SCs usually undergo extensive metabolism, and therefore their main metabolites must be identified for the detection in biological matrices, particularly in urine. Controlled human studies are usually not possible for ethical reasons; thus, alternative models must be used. The aim of this work was to predict the in vitro and in vivo metabolic patterns of 7-azaindole-derived SCs using 1-(5-fluoropentyl)-N-(2-phenylpropan-2-yl)-1H-pyrollo[2,3-b]pyridin-3-carboxamide (cumyl-5F-P7AICA) as an example. Different in vitro (pooled human liver S9 fraction, pooled human liver microsomes, and pig liver microsomes) and in vivo (rat and pig) systems were compared. Monooxygenase isoenzymes responsible for the most abundant phase I steps, namely oxidative defluorination (OF) followed by carboxylation, monohydroxylation, and ketone formation, were identified. In both in vivo models, OF/carboxylation and N-dealkylation/monohydroxylation/sulfation could be detected. Regarding pHS9 and pig urine, monohydroxylation/sulfation or glucuronidation was also abundant. Furthermore, the parent compound could still be detected in all models. Initial monooxygenase activity screening revealed the involvement of CYP2C19, CYP3A4, and CYP3A5. Therefore, in addition to the parent compound, the OF/carboxylated and monohydroxylated (and sulfated or glucuronidated) metabolites can be recommended as urinary targets. In comparison to literature, the pig model predicts best the human metabolic pattern of cumyl-5F-P7AICA. Furthermore, the pig model should be suitable to mirror the time-dependent excretion pattern of parent compounds and metabolites.

Adding more "spice" to the pot: A review of the chemistry and pharmacology of newly emerging heterocyclic synthetic cannabinoid receptor agonists

Synthetic cannabinoid receptor agonists (SCRAs) first appeared on the international recreational drug market in the early 2000s in the form of SCRA-containing herbal blends. Due to the cannabimimetic effects associated with the consumption of SCRAs, they have acquired an ill-informed reputation for being cheap, safe, and legal alternatives to illicit cannabis. Possessing high potency and affinity for the human cannabinoid receptor subtype-1 (CB₁ ) and -2 (CB₂ ), it is now understood that the recreational use of SCRAs can have severe adverse health consequences. The major public health problem arising from SCRA use has pressed legislators around the world to employ various control strategies to curb their recreational use. To circumvent legislative control measures, SCRA manufacturers have created a wide range of SCRA analogs that contain, more recently, previously unencountered azaindole, γ-carbolinone, or carbazole heterocyclic scaffolds. At present, little information is available regarding the chemical syntheses of these newly emerging classes of SCRA, from a clandestine perspective. When compared with previous generations of indole- and indazole-type SCRAs, current research suggests that many of these heterocyclic SCRA analogs maintain high affinity and efficacy at both CB₁ and CB₂ but largely evade legislative control. This review highlights the importance of continued research in the field of SCRA chemistry and pharmacology, as recreational SCRA use remains a global public health issue and represents a serious control challenge for law enforcement agencies.