Comprehensive investigation on synthetic cannabinoids: Metabolic behavior and potency testing,using 5F‐APP‐PICA and AMB‐FUBINACA as model compounds

Synthetic cannabinoids (SCs) represented 45% of new psychoactive substances seizures in Europe (data from 2016). The consumption of SCs is an issue of concern due to their still unknown toxicity and effects on human health, the great variety of compounds synthetized, and the continuous modifications being made to their chemical structure to avoid regulatory issues. These compounds are extensively metabolized in the organism and often cannot be detected as the intact molecule in human urine. The monitoring of SCs in forensic samples must be performed by the analysis of their metabolites. In this work, a workflow for the comprehensive study of SC consumption is proposed and applied to 5F‐APP‐PICA (also known as PX 1 or SRF‐30) and AMB‐FUBINACA (also known as FUB‐AMB or MMB‐FUBINACA), based not only on the elucidation of their metabolites but also including functional data using the NanoLuc approach, previously published. Both cannabinoids were completely metabolized by human hepatocytes (12 and 8 metabolites were elucidated by high resolution mass spectrometry for 5F‐APP‐PICA and AMB‐FUBINACA, respectively) and therefore suitable consumption markers are proposed. The bioassays revealed that 5F‐APP‐PICA presented lower activity than AMB‐FUBINACA at CB1 and CB2 receptors, based on the half maximal effective concentration (EC₅₀) and the maximum response (E_max). These results are in agreement with the different intoxication cases found in the literature for AMB‐FUBINACA.     

Rapid and sensitive screening and confirmation of thirty‐four aminocarbonyl/carboxamide (NACA) and arylindole synthetic cannabinoid drugs in human whole blood

We describe the development and validation of a method for the screening and confirmation of a range of chemically diverse synthetic cannabinoid drugs in human whole blood. The method targets the better known arylindole compounds as well as the emerging aminocarbonyl/ carboxamide (NACA) compounds. The approach consists of two separate extraction procedures designed to optimize recovery of each of these two classes, followed by analysis by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The most significant novel compounds added were AB‐FUBINACA, ADBICA, 5 F‐ADBICA, ADB‐PINACA, ADB‐FUBINACA, ADB‐FUBINACA, 5 F‐ADB‐PINACA, 5 F‐ADB‐PINACA, AB‐PINACA, AB‐CHMINACA, and ADB‐CHMINACA. A third procedure is described for the quantitative confirmation of those compounds for which deuterated internal standards permitted quantitative analysis, including JWH‐018, JWH‐122, JWH‐081, JWH‐210, AM‐2201, XLR‐11, and UR‐144. The methods were successfully validated according to Scientific Working Group in Forensic Toxicology (SWGTOX) protocol for 34 compounds in common use in the United States in the period of 2014 and 2015, although other substances, unknown at the time may have been introduced to the market over the same time period. The method was determined to be free from carry‐over between samples, and no interference was found from other common therapeutic abused or novel psychoactive drugs. The methods were applied to the analysis of 1142 blood samples from forensic investigations, including post‐mortem examinations and driving impairment cases. The drugs most frequently detected were AB‐CHMINACA (18.6%), ADB‐CHMINACA (15%), XLR‐11 (5.5%), AB‐FUBINACA (4.5%), AB‐PINACA (3.9%), and ADB‐FUBINACA (2.3%). Copyright © 2016 John Wiley & Sons, Ltd.     

Freeze‐thaw stability and long‐term stability of 84 synthetic cannabinoids in serum

Information about stability of synthetic cannabinoids is important to give recommendations for storage conditions in cases in which use of synthetic cannabinoids is suspected. In this study, freeze‐thaw stability (3 cycles at ‐20 °C at 1.5 ng/mL) and long‐term stability at room temperature, 4°C and ‐20°C (for 150 days) were tested by a validated liquid chromatographic‐mass spectrometric method for 80 synthetic cannabinoids. Results demonstrated good freeze‐thaw stability for most of the substances. For 5 F‐ABICA (72.6% of peak area of time point zero), 5 F‐ 2 ADB PINACA 2 Isomer (68.7 %), 5Cl‐AB‐PINACA (84.2 %), AB FUBINACA 2‐Isomer (33.5 %), 5 F‐PCN (89.7 %), ADB‐FUBINACA (78.0 %), EG 018 (88.9 %), and PX‐1 (89.4 %) three freeze‐thaw cycles led to absolute peak areas < 90% compared to 6 control samples. For 51 of the 84 substances, stability in serum could be demonstrated after 315 days of storage at ‐20°C. For 82 of the 84 substances, stability in serum could be shown for at least 1 month at ‐20°C. Long‐ term stability at 4°C or 20°C showed worse results. Therefore, it is our recommendation to store real serum samples at ‐20°C until analysis. Copyright © 2016 John Wiley & Sons, Ltd.     

Application of an activity‐based receptor bioassay to investigate the in vitro activity of selected indole‐ and indazole‐3‐carboxamide‐based synthetic cannabinoids at CB1 and CB2 receptors

Synthetic cannabinoids (SCs) are the most chemically diverse group of new psychoactive substances. This group has been associated with several intoxications, many with fatal outcomes. Although advancements have been achieved in pharmacology, metabolism, and detection of these compounds in recent years, these aspects are still unresolved for many SCs. The aim of this study was to investigate the in vitro potency of 14 indole‐ and indazole‐based SCs by applying a stable CB1 or CB2 receptor activation assay and correlating the activity with their structure. The half‐maximal effective concentration (EC₅₀) of 5‐chloropentyl, 5‐bromopentyl, and 5‐iodopentyl JWH‐122 analogs varied from 74.1 to 283.7 nM for CB1 and 7.05 to 23.4 nM for CB2, where the addition of a chlorine atom enhanced the potency at CB1 compared with the bromo and iodo analogs. AM‐2201 was the most active at CB1 within this naphthoylindole family, with an EC₅₀ of 23.5 nM but with the lowest efficacy (E_max 98.8%). Within the indole‐3‐carboxamide derivatives, 5F‐MDMB‐PICA was the most active compound, with a CB1/CB2 EC₅₀ of 3.26/0.87 nM and an E_max around three times higher than JWH‐018. ADB‐FUBINACA was the most potent tested SC overall, with a CB1/CB2 EC₅₀ of 0.69/0.59 nM, and an E_max around 3‐fold higher than that for JWH‐018 at CB1. The data obtained in this study confirm how small differences in the structure of SCs might lead to large differences in their activity, especially at CB1, which may be correlated with differences in their toxic effects in humans.     

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.     

Fatal intoxication by 5F–ADB and diphenidine: Detection,quantification, and investigation of their main metabolic pathways in humans by LC/MS/MS and LC/Q‐TOFMS

Despite the implementation of a new blanket scheduling system in 2013, new psychoactive substance (NPS) abuse remains a serious social concern in Japan. We present a fatal intoxication case involving 5F–ADB (methyl 2‐[1‐(5‐fluoropentyl)‐1H–indazole‐3‐carboxamido]‐3,3‐dimethylbutanoate) and diphenidine. Postmortem blood screening by liquid chromatography/quadrupole time‐of‐flight mass spectrometry (LC/Q‐TOFMS) in the information‐dependent acquisition mode only detected diphenidine. Further urinary screening using an in‐house database containing NPS and metabolites detected not only diphenidine but also possible 5F–ADB metabolites; subsequent targeted screening by LC/tandem mass spectrometry (LC/MS/MS) allowed for the detection of a very low level of unchanged 5F–ADB in postmortem heart blood. Quantification by standard addition resulted in the postmortem blood concentrations being 0.19 ± 0.04 ng/mL for 5F–ADB and 12 ± 2.6 ng/mL for diphenidine. Investigation of the urinary metabolites revealed pathways involving ester hydrolysis (M1) and oxidative defluorination (M2), and further oxidation to the carboxylic acid (M3) for 5F–ADB. Mono‐ and di‐hydroxylated diphenidine metabolites were also found. The present case demonstrates the importance of urinary metabolite screening for drugs with low blood concentration. Synthetic cannabinoids (SCs) fluorinated at the terminal N‐alkyl position are known to show higher cannabinoid receptor affinity relative to their non‐fluorinated analogues; 5F–ADB is no exception with high CB₁ receptor activity and much greater potency than Δ⁹‐THC and other earlier SCs, thus we suspect its acute toxicity to be high compared to other structurally related SC analogues. The low blood concentration of 5F–ADB may be attributed to enzymatic and/or non‐enzymatic degradation, and further investigation into these possibilities is underway.     

Extraordinary long detection window of a synthetic cannabinoid metabolite in human urine – Potential impact on therapeutic decisions

Synthetic cannabinoids (SCs) have become established drugs of abuse. They play an increasing role in drug therapy, where abstinence control testing is required. Differentiation between recent drug uptake and uptake in the distant past is important for drug therapy. This study aimed to evaluate the detection window of a metabolite commonly used as a consumption marker for AB‐FUBINACA and AMB‐FUBINACA (synonym: FUB‐AMB) in urine analysis. The acidic hydrolysis metabolite was quantified in urine samples of a drug user by applying a validated analytical method. The concentration profile of the metabolite was correlated with usage data of the subject. Pharmacokinetic properties of AB‐FUBINACA were collected by analysis of serum and urine samples from a controlled administration study (single oral ingestion of AB‐FUBINACA). Thirteen urine samples were taken without advance notice over 2 years. The metabolite was detected in the first urine sample at 0.77 ng/mg creatinine and subsequently in concentrations ranging from 0.06 to 0.29 ng/mg creatinine. Usage data showed credible abstinence from SCs during this period. The pharmacokinetic properties observed within the controlled self‐administration study supported the hypothesis of distribution into deeper compartments and long‐lasting elimination (serum concentration–time curve showing biphasic kinetics). An elimination phase of over 1 year after the last drug uptake seems plausible in cases of extensive consumption. To avoid misinterpretation of positive findings, we recommend testing patients with known SC use at the beginning of the abstinence program and to re‐test continuously at short time intervals. These data enable the correct interpretation of analytical findings.     

Detection of the recently emerged synthetic cannabinoid 5F–MDMB‐PICA in ‘legal high’ products and human urine samples

Indole or indazole‐based synthetic cannabinoids (SCs) bearing substituents derived from valine or tert‐leucine are frequently abused new psychoactive substances (NPS). The emergence of 5F–MDMB‐PICA (methyl N‐{[1‐(5‐fluoropentyl)‐1H–indol‐3‐yl]carbonyl}‐3‐methylvalinate) on the German drug market is a further example of a substance synthesized in the context of scientific research being misused by clandestine laboratories by adding it to ‘legal high’ products. In this work, we present the detection of 5F–MDMB‐PICA in several legal high products by gas chromatography–mass spectrometry (GC–MS) analysis. To detect characteristic metabolites suitable for a proof of 5F–MDMB‐PICA consumption by urine analysis, pooled human liver microsome (pHLM) assays were performed and evaluated using liquid chromatography–tandem mass spectrometry (LC–MS/MS) and liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐QToF‐MS) techniques to generate reference spectra of the in vitro phase I metabolites. The in vivo phase I metabolism was investigated by the analysis of more than 20 authentic human urine specimens and compared to the data received from the pHLM assay. Biotransformation of the 5‐fluoropentyl side chain and hydrolysis of the terminal methyl ester bond are main phase I biotransformation steps. Two of the identified main metabolites formed by methyl ester hydrolysis or mono‐hydroxylation at the indole ring system were evaluated as suitable urinary biomarkers and discussed regarding the interpretation of analytical findings. Exemplary analysis of one urine sample for 5F–MDMB‐PICA phase II metabolites showed that two of the main phase I metabolites are subject to extensive glucuronidation prior to renal excretion. Therefore, conjugate cleavage is reasonable for enhancing sensitivity. Commercially available immunochemical pre‐tests for urine proved to be unsuitable for the detection of 5F–MDMB‐PICA consumption. Copyright © 2017 John Wiley & Sons, Ltd.     

Identification of AB‐FUBINACA metabolites in authentic urine samples suitable as urinary markers of drug intake using liquid chromatography quadrupole tandem time of flight mass spectrometry

Synthetic cannabinoids are a group of psychoactive drugs presently widespread among drug users in Europe. Analytical methods to measure these compounds in urine are in demand as urine is a preferred matrix for drug testing. For most synthetic cannabinoids, the parent compounds are rarely detected in urine. Therefore urinary metabolites are needed as markers of drug intake. AB‐FUBINACA was one of the top three synthetic cannabinoids most frequently found in seizures and toxicological drug screening in Sweden (2013–2014). Drug abuse is also reported from several other countries such as the USA and Japan. In this study, 28 authentic case samples were used to identify urinary markers of AB‐FUBINACA intake using liquid chromatography quadrupole tandem time of flight mass spectrometry and human liver microsomes. Three metabolites suitable as markers of drug intake were identified and at least two of them were detected in all but one case. In total, 15 urinary metabolites of AB‐FUBINACA were reported, including hydrolxylations on the indazole ring and the amino‐oxobutane moiety, dealkylations and hydrolysis of the primary amide. No modifications on the fluorobenzyl side‐chain were observed. The parent compound was detected in 54% of the case samples. Also, after three hours of incubation with human liver microsomes, 77% of the signal from the parent compound remained. Copyright © 2015 John Wiley & Sons, Ltd.     

Discrimination between closely related synthetic cannabinoids by GC–Cold–EI–MS

Gas chromatography thermal‐electron ionization mass spectrometry (GC–EI–MS) is an established method for the identification of mind‐altering substances and is routinely used by forensic laboratories. However, some commonly analyzed drugs of abuse, relating to the synthetic cannabinoids receptor agonist group (SCs), pose a challenge for this conventional technique. As the molecular cation radicals of many excited SCs are labile within the ion source, the relative abundance of the molecular ions obtained by the GC‐EI‐MS is often too small to allow discrimination of structurally related drugs. In contrast, the cold‐electron ionization (cold‐EI) method allows the enhancement and clear identification of the molecular ions, while maintaining the ability to compare unknown analytes with comprehensive mass spectrum libraries. This technique was explored for mass‐spectrometric identification and unambiguous differentiation of 15 emerging synthetic cannabinoids found on the drug market in Israel and elsewhere. The current method was demonstrated to discriminate pairs of closely related SCs: FUB‐PB‐22 and FDU‐PB‐22, and 5F–PB‐22 and NM‐2201. In addition, the dependence of the molecular ion enhancement on the cold‐EI parameters was examined. Finally, analysis of SCs from seized street samples provided by the Israeli police demonstrates the enhanced identification power of GC–cold–EI–MS.     

Detection of the recently emerged synthetic cannabinoid 4F‐MDMB‐BINACA in “legal high” products and human urine specimens

Synthetic cannabinoids (SCs) remain one of the largest groups of new psychoactive substances (NPS) on the European drug market. Although the number of new derivatives occurring on the market has dropped in the last two years, newly emerging NPS still represent a challenge for laboratories performing forensic drug analysis in biological matrices. The newly emerged SC 4F‐MDMB‐BINACA has been reported by several law enforcement agencies in Europe and the USA since November 2018. This work aimed at revealing urinary markers to prove uptake of 4F‐MDMB‐BINACA and differentiate from the use of structurally similar SCs. Phase‐I metabolites detected in human urine specimens were confirmed by phase‐I metabolites generated in vitro using a pooled human liver microsomes (pHLM) assay. Seized materials and test‐purchased “legal high” products were analyzed by gas chromatography–mass spectrometry (GC–MS) and liquid chromatography?quadrupole‐time‐of‐flight?mass spectrometry (LC?qToF?MS). Human urine specimens and pHLM assay extracts were measured with liquid chromatography?electrospray ionization?tandem mass spectrometry (LC?ESI?MS/MS) and confirmed by LC?qToF?MS. In January 2019, the Institute of Legal Medicine in Erlangen (Germany) identified 4F‐MDMB‐BINACA in three herbal blends. During the same time period, the described SC was identified in a research chemical purchased online. Investigation of phase‐I metabolism led to the metabolites M10 (ester hydrolysis) and M11 (ester hydrolysis and dehydrogenation) as reliable urinary markers. Widespread distribution on the German drug market was proven by analysis of urine samples from abstinence control programs and by frequent detection of 4F‐MDMB‐BINACA in “herbal blends” and “‘research chemicals” purchased via the Internet.     

Phase I metabolism of the carbazole‐derived synthetic cannabinoids EG‐018, EG‐2201, and MDMB‐CHMCZCA and detection in human urine samples

Synthetic cannabinoids (SCs) are a structurally diverse class of new psychoactive substances. Most SCs used for recreational purposes are based on indole or indazole core structures. EG‐018 (naphthalen‐1‐yl(9‐pentyl‐9H‐carbazol‐3‐yl)methanone), EG‐2201 ((9‐(5‐fluoropentyl)‐9H‐carbazol‐3‐yl)(naphthalen‐1‐yl)methanone), and MDMB‐CHMCZCA (methyl 2‐(9‐(cyclohexylmethyl)‐9H‐carbazole‐3‐carboxamido)‐3,3‐dimethylbutanoate) are 3 representatives of a structural subclass of SCs, characterized by a carbazole core system. In vitro and in vivo phase I metabolism studies were conducted to identify the most suitable metabolites for the detection of these substances in urine screening. Detection and characterization of metabolites were performed by liquid chromatography–electrospray ionization–tandem mass spectrometry (LC–ESI–MS/MS) and liquid chromatography–electrospray ionization–quadrupole time‐of‐flight–mass spectrometry (LC–ESI–QToF–MS). Eleven in vivo metabolites were detected in urine samples positive for metabolites of EG‐018 (n = 8). A hydroxypentyl metabolite, most probably the 4‐hydroxypentyl isomer, and an N‐dealkylated metabolite mono‐hydroxylated at the carbazole core system were most abundant. In vitro studies of EG‐018 and EG‐2201 indicated that oxidative defluorination of the 5‐fluoropentyl side chain of EG‐2201 as well as dealkylation led to common metabolites with EG‐018. This has to be taken into account for interpretation of analytical findings. A differentiation between EG‐018 and EG‐2201 (n = 1) uptake is possible by the detection of compound‐specific in vivo phase I metabolites evaluated in this study. Out of 30 metabolites detected in urine samples of MDMB‐CHMCZCA users (n = 20), a metabolite mono‐hydroxylated at the cyclohexyl methyl tail is considered the most suitable compound‐specific consumption marker while a biotransformation product of mono‐hydroxylation in combination with hydrolysis of the terminal methyl ester function provides best sensitivity due to its high abundance.     

Study on the phase I metabolism of novel synthetic cannabinoids,APICA and its fluorinated analogue

The data are reported for an in vitro metabolism study of two novel synthetic cannabinoids, N‐(1‐adamantyl)‐1‐pentyl‐1H‐indole‐3‐carboxamide (APICA) and its fluorinated analog N‐(1‐adamantyl)‐1‐(5‐fluoropentyl)‐1H‐indole‐3‐carboxamide (5F‐APICA, STS‐135), which are active ingredients of smoking mixtures sold in Russia since 2012. The cannabinoids were isolated from herbal mixtures using preparative liquid chromatography and then incubated with human liver microsomes (HLMs). The formed metabolites were characterized by liquid chromatography – triple quadrupole mass spectrometry and high‐resolution mass spectrometry with electrospray ionization in positive ion mode. It was found that HLMs produce mono‐, di‐, and trihydroxylated metabolites, as well as N‐desalkyl metabolites, which can be further hydroxylated; the amide bond resisted the metabolic cleavage. For 5F‐APICA, a series of oxidative defluorination products formed as well. For in vivo confirmation of the formed in vitro metabolites, spot urine samples from drug users were analyzed with the created method. It was shown that for the detection of APICA abuse, the preferred metabolites are the di‐ and tri‐hydroxylated species, while in case of 5F‐APICA, a monohydroxy metabolite is a better target. The N‐despentyl (desfluoropentyl) hydroxyadamantyl metabolite also provides good retrospectivity to confirm the administration of any of these cannabinoids. Copyright © 2014 John Wiley & Sons, Ltd.     

Screening,quantification, and confirmation of synthetic cannabinoid metabolites in urine by UHPLC–QTOF–MS

Synthetic cannabinoids are one of the most significant groups within the category new psychoactive substances (NPS) and in recent years new compounds have continuously been introduced to the market of recreational drugs. A sensitive and quantitative screening method in urine with metabolites of frequently seized compounds in Norway (AB‐FUBINACA, AB‐PINACA, AB‐CHMINACA, AM‐2201, AKB48, 5F‐AKB48, BB‐22, JWH‐018, JWH‐073, JWH‐081, JWH‐122, JWH‐203, JWH‐250, PB‐22, 5F‐PB‐22, RCS‐4, THJ‐2201, and UR‐144) using ultra‐high pressure liquid chromatography–quadrupole time of flight–mass spectrometry (UHPLC–QTOF–MS) has been developed. The samples were treated with ß‐glucuronidase prior to extraction and solid‐phase extraction was used. Liquid handling was automated using a robot. Chromatographic separation was achieved using a C18‐column and a gradient of water and acetonitrile, both with 0.1% formic acid. Each sample was initially screened for identification and quantification followed by a second injection for confirmation. The concentrations by which the compounds could be confirmed varied between 0.1 and 12 ng/mL. Overall the validation showed that the method fulfilled the set criteria and requirements for matrix effect, extraction recovery, linearity, precision, accuracy, specificity, and stability. One thousand urine samples from subjects in drug withdrawal programs were analyzed using the presented method. The metabolite AB‐FUBINACA M3, hydroxylated metabolite of 5F‐AKB48, hydroxylated metabolite of AKB48, AKB48 N‐pentanoic acid, 5F‐PB‐22 3‐carboxyindole, BB‐22 3‐carboxyindole, JWH‐018 N‐(5‐hydroxypentyl), JWH‐018 N‐pentanoic acid, and JWH‐073 N‐butanoic acid were quantified and confirmed in 2.3% of the samples. The method was proven to be sensitive, selective and robust for routine use for the investigated metabolites.     

Metabolic profiling of synthetic cannabinoid 5F‐ADB by human liver microsome incubations and urine samples using high‐resolution mass spectrometry

5F‐ADB (methyl 2‐{[1‐(5‐fluoropentyl)‐1H‐indazole‐3‐carbonyl] amino}‐3,3‐dimethylbutanoate) is a frequently abused new synthetic cannabinoid that has been sold since at least the end of 2014 on the drug market and has been classified as an illicit drug in most European countries, as well as Turkey, Japan, and the United States. In this study, the in vitro metabolism of 5F‐ADB was investigated by using pooled human liver microsomes (HLMs) assay and liquid chromatography‐high‐resolution mass spectrometry (LC–HRMS). 5F‐ADB (5 μmol/L) was incubated with HLMs for up to 3 hours, and the metabolites were identified using LC–HRMS and software‐assisted data mining. The in vivo metabolism was investigated by the analysis of 30 authentic urine samples and was compared to the data received from the in vitro metabolism study. Less than 3.3% of the 5F‐ADB parent compound remained after 1 hour of incubation, and no parent drug was detected after 3 hours. We identified 20 metabolites formed via ester hydrolysis, N‐dealkylation, oxidative defluorination, hydroxylation, dehydrogenation, further oxidation to N‐pentanoic acid and glucuronidation or a combination of these reactions in vitro. In 12 urine samples (n = 30), 5F‐ADB was detected as the parent drug. Three of the identified main metabolites 5F‐ADB carboxylic acid (M20), monohydroxypentyl‐5F‐ADB (M17), and carboxypentyl ADB carboxylic acid (M8) were suggested as suitable urinary markers. The screening of 8235 authentic urine samples for identified 5F‐ADB metabolites in vitro resulted in 3135 cases of confirmed 5F‐ADB consumption (38%).     

In vitro Phase I metabolism of indazole carboxamide synthetic cannabinoid MDMB‐CHMINACA via human liver microsome incubation and high‐resolution mass spectrometry

Synthetic cannabinoids have proliferated over the last decade and have become a major public health and analytical challenge, critically impacting the clinical and forensic communities. Indazole carboxamide class synthetic cannabinoids have been particularly rampant, and exhibit severe toxic effects upon consumption due to their high binding affinity and potency at the cannabinoid receptors (CB₁ and CB₂). MDMB‐CHMINACA, methyl 2‐[1‐(cyclohexylmethyl)‐1H‐indazole‐3‐carboxamido]‐3,3‐dimethylbutanoate, a compound of this chemical class, has been identified in forensic casework and is structurally related to several other synthetic cannabinoids. This study presents the first extensive report on the Phase I metabolic profile of MDMB‐CHMINACA, a potent synthetic cannabinoid. The in vitro metabolism of MDMB‐CHMINACA was determined via incubation with human liver microsomes and high‐resolution mass spectrometry. The accurate masses of precursor and fragments, mass error (ppm), and chemical formula were obtained for each metabolite. Twenty‐seven metabolites were identified, encompassing twelve metabolite types. The major biotransformations observed were hydroxylation and ester hydrolysis. Hydroxylations were located predominantly on the cyclohexylmethyl (CHM) moiety. Ester hydrolysis was followed by additional biotransformations, including dehydrogenation; mono‐ and dihydroxylation and ketone formation, each with dehydrogenation. Minor metabolites were identified and reported. The authors propose that CHM‐monohydroxylated metabolites specific to MDMB‐CHMINACA are the most suitable candidates for implementation into bioanalytical assays to demonstrate consumption of this synthetic cannabinoid. Due to the structural similarity of MDMB‐CHMINACA and currently trending synthetic cannabinoids whose metabolic profiles have not been reported, the results of this study can be used as a guide to predict their metabolic pathways.     

Phase I metabolism of the highly potent synthetic cannabinoid MDMB‐CHMICA and detection in human urine samples

Among the recently emerged synthetic cannabinoids, MDMB‐CHMICA (methyl N ‐{[1‐(cyclohexylmethyl)‐1H ‐indol‐3‐yl]carbonyl}‐3‐methylvalinate) shows an extraordinarily high prevalence in intoxication cases, necessitating analytical methods capable of detecting drug uptake. In this study, the in vivo phase I metabolism of MDMB‐CHMICA was investigated using liquid chromatography‐electrospray ionization‐tandem mass spectrometry (LC‐ESI‐MS/MS) and liquid chromatography‐electrospray ionization‐quadrupole time‐of‐flight‐mass spectrometry (LC‐ESI‐Q ToF‐MS) techniques. The main metabolites are formed by hydrolysis of the methyl ester and oxidation of the cyclohexyl methyl side chain. One monohydroxylated metabolite, the ester hydrolysis product and two further hydroxylated metabolites of the ester hydrolysis product are suggested as suitable targets for a selective and sensitive detection in urine. All detected in vivo metabolites could be verified in vitro using a human liver microsome assay. Two of the postulated main metabolites were successfully included in a comprehensive LC‐ESI‐MS/MS screening method for synthetic cannabinoid metabolites. The screening of 5717 authentic urine samples resulted in 818 cases of confirmed MDMB‐CHMICA consumption (14%). Since the most common route of administration is smoking, smoke condensates were analyzed to identify relevant thermal degradation products. Pyrolytic cleavage of the methyl ester and amide bond led to degradation products which were also formed metabolically. This is particularly important in hair analysis, where detection of metabolites is commonly considered a proof of consumption. In addition, intrinsic activity of MDMB‐CHMICA at the CB₁ receptor was determined applying a cAMP accumulation assay and showed that the compound is a potent full agonist. Based on the collected data, an enhanced interpretation of analytical findings in urine and hair is facilitated. Copyright © 2016 John Wiley & Sons, Ltd.     

Functional evaluation of carboxy metabolites of synthetic cannabinoid receptor agonists featuring scaffolds based on L‐valine or L‐tert‐leucine

Indole‐ and indazole‐based synthetic cannabinoid receptor agonists (SCRAs), featuring valine or tert‐leucine substituents, are commonly abused new psychoactive substances (NPS). A major metabolic pathway for these SCRAs is hydrolysis of the terminal amide or methylester functionalities. Although these hydrolysis products were already detected as main ingredients in some “legal highs,” these metabolites are often poorly characterized. Here, we report a systematic investigation of the activity of 7 common hydrolysis metabolites of 15 SCRAs featuring scaffolds based on L‐valine or L‐tert‐leucine in direct comparison to their parent compounds. An activity‐based cannabinoid receptor 1 (CB₁) bio‐assay was used for activity profiling of SCRAs and their metabolites in a stable HEK293T cell system. The recruitment of β‐arrestin2 to the activated CB₁ (each fused to one part of a split Nanoluciferase) was provoked by adding the (putative) SCRAs. Luminescence of the functionally complemented luciferase was monitored by a 96‐well plate‐reader. The major hydrolysis metabolites of 5F‐AB‐PINACA, ADB‐CHMICA, ADB‐CHMINACA, ADB‐FUBICA, and their methyl‐ and ethylester derivatives showed no detectable CB₁ activation at concentrations up to 1 μM. On the other hand, metabolites of 5F‐ADB‐PINACA, AB‐CHMINACA, and ADB‐FUBINACA did retain activity, although significantly reduced as compared to the parent compounds (EC₅₀ values >100 nM). Activity‐based characterization of SCRAs and their metabolites at CB₁ may not only allow a better insight into the complex interplay between SCRAs and their metabolites in intoxications, but may also allow application of the concept of “activity equivalents” present in biological fluids or, alternatively, in confiscated materials.     

Analysis of 30 synthetic cannabinoids in oral fluid using liquid chromatography‐electrospray ionization tandem mass spectrometry

In recent years, the analysis of synthetic cannabinoids in human specimens has gained enormous importance in the broad field of drug testing. Nevertheless, the considerable structural diversity among synthetic cannabinoids already identified in ‘herbal mixtures’ hampers the development of comprehensive analytical methods. As the identification of the main metabolites of newly appearing substances is very laborious and time‐consuming, the detection of the parent compounds in blood samples is the current approach of choice for drug abstinence testing. Whenever blood sampling is not possible however, the need for alternative matrices arises. In this article, we present a fully validated liquid chromatography‐electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) method for the analysis of 30 synthetic cannabinoids in oral fluid samples collected with the Dräger DCD 5000 collection device. The method proved to be suitable for the quantification of 28 substances. The limits of detection were in the range from 0.015 to 0.9 ng/ml, while the lower limits of quantification ranged from 0.15 to 3.0 ng/ml. The method was successfully applied to 264 authentic samples during routine analysis. A total of 31 samples (12%) was tested positive for at least one of the following synthetic cannabinoids: AM‐694, AM‐2201, JWH‐018, JWH‐019, JWH‐081, JWH‐122, JWH‐203, JWH‐210, JWH‐250, JWH‐307, MAM‐2201, and RCS‐4. Given that stabilization of the collection pads after sampling is warranted, the collection device provides satisfactory sensitivity. Hence, whenever blood sampling is not possible, the Dräger DCD 5000 collection device offers a good tool for the analysis of synthetic cannabinoids in oral fluid in the broad field of drug testing. Copyright © 2012 John Wiley & Sons, Ltd.     

Quantitative urine confirmatory testing for synthetic cannabinoids in randomly collected urine specimens

Synthetic cannabinoid intake is an ongoing health issue worldwide, with new compounds continually emerging, making drug testing complex. Parent synthetic cannabinoids are rarely detected in urine, the most common matrix employed in workplace drug testing. Optimal identification of synthetic cannabinoid markers in authentic urine specimens and correlation of metabolite concentrations and toxicities would improve synthetic cannabinoid result interpretation. We screened 20 017 randomly collected US military urine specimens between July 2011 and June 2012 with a synthetic cannabinoid immunoassay yielding 1432 presumptive positive specimens. We analyzed all presumptive positive and 1069 negative specimens with our qualitative synthetic cannabinoid liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) method, which confirmed 290 positive specimens. All 290 positive and 487 randomly selected negative specimens were quantified with the most comprehensive urine quantitative LC‐MS/MS method published to date; 290 specimens confirmed positive for 22 metabolites from 11 parent synthetic cannabinoids. The five most predominant metabolites were JWH‐018 pentanoic acid (93%), JWH‐N‐hydroxypentyl (84%), AM2201 N‐hydroxypentyl (69%), JWH‐073 butanoic acid (69%), and JWH‐122 N‐hydroxypentyl (45%) with 11.1 (0.1‐2,434), 5.1 (0.1‐1,239), 2.0 (0.1‐321), 1.1 (0.1‐48.6), and 1.1 (0.1‐250) µg/L median (range) concentrations, respectively. Alkyl hydroxy and carboxy metabolites provided suitable biomarkers for 11 parent synthetic cannabinoids; although hydroxyindoles were also observed. This is by far the largest data set of synthetic cannabinoid metabolites urine concentrations from randomly collected workplace drug testing specimens rather than acute intoxications or driving under the influence of drugs. These data improve the interpretation of synthetic cannabinoid urine test results and suggest suitable urine markers of synthetic cannabinoid intake. This article is a U.S. Government work and is in the public domain in the USA.