High-resolution mass spectrometric metabolite profiling of a novel synthetic designer drug, N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide (STS-135), using cryopreserved human hepatocytes and assessment of metabolic stability with human liver microsomes

Comprehensive characterization of organic compounds in indoor dust after generic sample preparation with SUPRAS and analysis by LC-HRMS/MS

In this study supramolecular solvents (SUPRAS) are employed for the first time to perform a wide screening of organic compounds in indoor dust samples. The potential of SUPRAS to efficiently extract a wide polarity range of compounds, and to simplify and improve the green properties of sample treatment in this area are discussed. SUPRAS made up of inverse aggregates of hexanol in tetrahydrofuran:water mixtures, which have been previously and successfully applied to the target determination of a variety of organic contaminants in different environmental matrices, were employed. Analysis was done with liquid chromatography and high resolution mass spectrometry. Twelve samples from public buildings (six educative buildings, two food stores, two nightclubs, one office and a coffee shop) were collected in South Spain. A total of 146 compounds were detected by target (∼33 %), suspect (∼55 %) and non-target screening (∼12 %). Around 86 % of all the compounds were identified (or tentatively identified) with levels of confidence equal or higher than 3. Novel designer drugs of abuse, unreported organophosphorus compounds and well-known organic contaminants, such as bisphenols, parabens, phthalates and flame retardants are reported. Differences with previous studies on wide screening of indoor dust reveal the influence of the employed databases for data processing and of the extraction method together with the different contamination profiles given by the sample location.

Pressure-Sensitive Adhesive Combined with Paper Spray Mass Spectrometry for Low-Cost Collection and Analysis of Drug Residues

Illicit drug use causes over half a million deaths worldwide every year. Drugs of abuse are commonly smuggled through customs and border checkpoints and, increasingly, through parcel delivery services. Improved methods for detection of trace drug residues from surfaces are needed. Such methods should be robust, fieldable, sensitive, and capable of detecting a wide range of drugs. In this work, commercially produced paper with a pressure-sensitive adhesive coating was utilized for the collection and analysis of trace drug residues by paper spray mass spectrometry (MS). This modified substrate was used to combine sample collection of drug residues from surfaces with rapid detection using a single paper spray ticket. The all-in-one ticket was used to probe different surfaces commonly encountered in forensic work including clothing, cardboard, glass, concrete, asphalt, and aluminum. A total of 10 drugs (acetyl fentanyl, fentanyl, clonazolam, cocaine, heroin, ketamine, methamphetamine, methylone, U-47700, and XLR-11) were evaluated and found to be detectable in the picogram range using a benchtop mass spectrometer and in the low nanogram range using a portable ion trap MS. The novel approach demonstrates a simple yet effective sampling strategy, allowing for rapid identification from difficult surfaces via paper spray mass spectrometry.

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.

Synthetic Cannabinomimetics: A Brief History and the Challenges They Pose for the Forensic Chemist

Since the first detection of synthetic cannabinomimetics in herbal smoking blends in 2008 the clandestine production of these compounds, based on seizure data, increased in number every year until ~2012. In recent years there has been a decline in synthetic cannabinomimetic production both in number and diversity. The synthetic details of the first generation cannabinoids were documented in the scientific and medical literature making production comparatively simple. Subsequent generations of synthetic cannabinoids involved more complex but still very practicable synthetic chemistry. This resulted in a period of rapid growth in synthetic cannabinoids creating a health crisis and problems for forensic chemists faced with many substances for which no certified reference materials existed. Routine forensic chemistry laboratories were well practiced at identifying known drugs using chromatographic–mass spectrometric techniques and comparison to reference materials. However as synthetic cannabinomimetics, often referred to in the literature as synthetic cannabinoids, appeared in large numbers, few laboratories were equipped with the nuclear magnetic resonance (NMR) spectrometers and high resolution mass spectrometers (HRMS) required for identification of unknown substances. These developments also challenged public prosecutors for opinions from forensic experts as to the legality or otherwise of these novel drugs.

Metabolic Profiling of a CB2 Agonist, AM9338, Using LC-MS and Microcoil-NMR: Identification of a Novel Dihydroxy Adamantyl Metabolite

Adamantyl groups are key structural subunit commonly used in many marketed drugs targeting diseases ranging from viral infections to neurological disorders. The metabolic disposition of adamantyl compounds has been mostly studied using LC-MS based approaches. However, metabolite quantities isolated from biological preparations are often insufficient for unambiguous structural characterization by NMR. In this work, we utilized microcoil NMR in conjunction with LC-MS to characterize liver microsomal metabolites of an adamantyl based CB2 agonist AM9338, 1-(3-(1H-1,2,3-triazol-1-yl) propyl)-N-(adamantan-1-yl)-1H-indazole-3-carboxamide, a candidate compound for potential multiple sclerosis treatment. We have identified a total of 9 oxidative metabolites of AM9338 whereas mono- or di-hydroxylation of the adamantyl moiety is the primary metabolic pathway. While it is generally believed that the tertiary adamantyl carbons are the preferred sites of CYP450 oxidation, both the mono- and di-hydroxyl metabolites of AM9338 show that the primary oxidative sites are located on the secondary adamantyl carbons. To our knowledge this di-hydroxylated metabolite is a novel adamantyl metabolite that has not been reported before. Further, the stereochemistry of both mono- and di-hydroxyl adamantyl metabolites has been determined using NOE correlations. Furthermore, docking of AM9338 into the CYP3A4 metabolic enzyme corroborates with our experimental findings, and the modelling results also provide a possible mechanism for the unusual susceptibility of adamantyl secondary carbons to metabolic oxidations. The novel dihydroxylated AM9338 metabolite identified in this study, along with the previously known adamantyl metabolites, gives a more complete picture of the metabolic disposition for adamantyl compounds.

Evaluation of covalent binding of flutamide and its risk assessment using 19F-NMR

The formation of reactive metabolites (RMs) is a problem in drug development that sometimes results in severe hepatotoxicity. As detecting RMs themselves is difficult, a covalent binding assay using expensive radiolabelled tracers is usually performed for candidate selection. This study aimed to provide a practical approach toward the risk assessment of hepatotoxicity induced by covalent binding before candidate selection. We focused on flutamide because it contains a trifluoromethyl group that shows a strong singlet peak by ¹⁹F nuclear magnetic resonance (NMR) spectrometry. The covalent binding of flutamide was evaluated using quantitative NMR and its risk for hepatotoxicity was assessed by estimating the RM burden, an index that reflects the body burden associated with RM exposure by determining the extent of covalent binding, clinical dose and in vivo clearance. The extent of covalent binding and RM burden was 296 pmol/mg/h and 37.9 mg/day, respectively. Flutamide was categorised as high risk with an RM burden >10 mg/day consistent with its clinical hepatotoxicity. These results indicate that a combination of covalent binding assay using ¹⁹F-NMR and RM burden is useful for the risk assessment of RMs without using radiolabelled compounds.

In-Silico Modeling in Drug Metabolism and Interaction: Current Strategies of Lead Discovery

BACKGROUND

Drug metabolism is a complex mechanism of human body systems to detoxify foreign particles, chemicals, and drugs through bio alterations. It involves many biochemical reactions carried out by invivo enzyme systems present in the liver, kidney, intestine, lungs, and plasma. After drug administration, it crosses several biological membranes to reach into the target site for binding and produces the therapeutic response. After that, it may undergo detoxification and excretion to get rid of the biological systems. Most of the drugs and its metabolites are excreted through kidney via urination. Some drugs and their metabolites enter into intestinal mucosa and excrete through feces. Few of the drugs enter into hepatic circulation where they go into the intestinal tract. The drug leaves the liver via the bile duct and is excreted through feces. Therefore, the study of total methodology of drug biotransformation and interactions with various targets is costly.

METHODS

To minimize time and cost, in-silico algorithms have been utilized for lead-like drug discovery. Insilico modeling is the process where a computer model with a suitable algorithm is developed to perform a controlled experiment. It involves the combination of both in-vivo and in-vitro experimentation with virtual trials, eliminating the non-significant variables from a large number of variable parameters. Whereas, the major challenge for the experimenter is the selection and validation of the preferred model, as well as precise simulation in real physiological status.

RESULTS

The present review discussed the application of in-silico models to predict absorption, distribution, metabolism, and excretion (ADME) properties of drug molecules and also access the net rate of metabolism of a compound.

CONCLUSION

It helps with the identification of enzyme isoforms; which are likely to metabolize a compound, as well as the concentration dependence of metabolism and the identification of expected metabolites. In terms of drug-drug interactions (DDIs), models have been described for the inhibition of metabolism of one compound by another, and for the compound-dependent induction of drug-metabolizing enzymes.

Identifying cytochrome P450s involved in oxidative metabolism of synthetic cannabinoid N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide (STS-135)

Synthetic cannabinoids (SCBs), designer drugs marketed as legal alternatives to marijuana, act as ligands to cannabinoid receptors; however, they have increased binding affinity and potency, resulting in toxicity symptoms such as cardiovascular incidents, seizures, and potentially death. N-(adamantan-1-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamide (STS-135) is a third generation SCB. When incubated with hepatocytes, it undergoes oxidation, hydrolysis, and glucuronidation, resulting in 29 metabolites, with monohydroxy STS-135 (M25) and dihydroxy STS-135 (M21) being the predominant metabolites. The enzymes responsible for this oxidative metabolism were unknown. Thus, the aim of this study was to identify the cytochrome P450 (P450s or CYPs) enzymes involved in the oxidative metabolism of STS-135. In this study, STS-135 was incubated with liver, intestinal, and brain microsomes and recombinant P450s to determine the enzymes involved in its metabolism. Metabolite quantification was carried out using ultra-performance liquid chromatography. STS-135 was extensively metabolized in HLMs and HIMs. Screening assays indicated CYP3A4 and CYP3A5 could be responsible for STS-135's oxidation. Through incubations with genotyped HLMs, CYP3A4 was identified as the primary oxidative enzyme. Interestingly, CYP2J2, a P450 isoform expressed in cardiovascular tissues, showed high activity towards the formation of M25 with a Km value of 11.4 μmol/L. Thus, it was concluded that STS-135 was primarily metabolized by CYP3A4 but may have extrahepatic metabolic pathways as well. Upon exposure to STS-135, individuals with low CYP3A4 activity could retain elevated blood concentration, resulting in toxicity. Additionally, CYP2J2 may aid in protecting against STS-135-induced cardiovascular toxicity.

In vitro metabolism of the synthetic cannabinoids PX-1, PX-2, and PX-3 by high-resolution mass spectrometry and their clearance rates in human liver microsomes

RATIONALE

N-(1-Amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indole-3-carboxamine (PX-1), N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide (PX-2), and N-(1-amino-1-oxo-3-phenylpropan-2-yl)-1-(cyclohexylmethyl)-1H-indazole-3-carboxamide (PX-3) are scheduled synthetic cannabinoids (SCs). Due to the lack of metabolism data and the extensive metabolism of SCs, consumption of these illicit substances is challenging to prove. The aim of this study was to investigate the metabolism of PX-1, PX-2, and PX-3 and propose marker metabolites to confirm their use.

METHODS

PX-1, PX-2, and PX-3 were incubated in pooled human liver microsomes (HLM) to evaluate the phase I metabolites which were identified using a Q-Exactive hybrid quadrupole-Orbitrap mass spectrometer. Metabolic stability studies were also performed to investigate the half-life and clearance rates using an Agilent 6470A triple quadrupole mass spectrometer.

RESULTS

The calculated half-lives were 15.1 ± 1.02, 3.4 ± 0.27, and 5.2 ± 0.89 min for PX-1, PX-2, and PX-3, respectively, in HLM. The calculated intrinsic clearance values were 0.046, 0.202, and 0.133 mL/min/mg for PX-1, PX-2, and PX-3, respectively. Four metabolites of PX-1, six metabolites of PX-2, and five phase I metabolites of PX-3 were detected. Oxidative deamination was the common biotransformation between the three compounds and there were no common metabolites.

CONCLUSIONS

The metabolic profiles of PX-1, PX-2, and PX-3 provide valuable information for the detection of their metabolites in forensic samples.

Metabolic stability and its role in the discovery of new chemical entities

Determination of metabolic profiles of new chemical entities is a key step in the process of drug discovery, since it influences pharmacokinetic characteristics of therapeutic compounds. One of the main challenges of medicinal chemistry is not only to design compounds demonstrating beneficial activity, but also molecules exhibiting favourable pharmacokinetic parameters. Chemical compounds can be divided into those which are metabolized relatively fast and those which undergo slow biotransformation. Rapid biotransformation reduces exposure to the maternal compound and may lead to the generation of active, non-active or toxic metabolites. In contrast, high metabolic stability may promote interactions between drugs and lead to parent compound toxicity. In the present paper, issues of compound metabolic stability will be discussed, with special emphasis on its significance, in vitro metabolic stability testing, dilemmas regarding in vitro-in vivo extrapolation of the results and some aspects relating to different preclinical species used in in vitro metabolic stability assessment of compounds.

The ongoing challenge of novel psychoactive drugs of abuse. Part I. Synthetic cannabinoids (IUPAC Technical Report)

In the past decade, the world has experienced a large increase in the number of novel compounds appearing on the illicit drug market for recreational purposes. Such substances are designed to circumvent governmental regulations; the illegal drug manufacturers take a known psychoactive compound reported in the scientific literature and slightly modify its chemical structure in order to produce analogues that will mimic the pharmacological activity of the original substance. Many of these novel substances are sold via the Internet. Among the various chemical classes, synthetic cannabinoid receptor modulators, commonly referred to as “synthetic cannabinoids” have been at the forefront, as demonstrated by the frequency of drug seizures, numerous severe toxic effects, and fatalities associated with some of these substances. This review presents the chemical structures of relevant synthetic cannabinoids and describes their mechanism of action, pharmacological features, metabolic pathways, and structure-activity relationships. It illustrates the approaches used in forensic testing, both for bulk analysis (drug seizures) and for analytical toxicology (biological matrices) and discusses aspects of regulation surrounding this drug class. This report is intended to provide pertinent information for the purposes of informing scientific, medical, social, and governmental bodies about this ever-evolving recreational drug class and the challenges it poses worldwide.

Pharmacokinetic parameters explain the therapeutic activity of antimicrobial agents in a silkworm infection model

Poor pharmacokinetic parameters are a major reason for the lack of therapeutic activity of some drug candidates. Determining the pharmacokinetic parameters of drug candidates at an early stage of development requires an inexpensive animal model with few associated ethical issues. In this study, we used the silkworm infection model to perform structure-activity relationship studies of an antimicrobial agent, GPI0039, a novel nitrofuran dichloro-benzyl ester, and successfully identified compound 5, a nitrothiophene dichloro-benzyl ester, as a potent antimicrobial agent with superior therapeutic activity in the silkworm infection model. Further, we compared the pharmacokinetic parameters of compound 5 with a nitrothiophene benzyl ester lacking chlorine, compound 7, that exerted similar antimicrobial activity but had less therapeutic activity in silkworms, and examined the metabolism of these antimicrobial agents in human liver fractions in vitro. Compound 5 had appropriate pharmacokinetic parameters, such as an adequate half-life, slow clearance, large area under the curve, low volume of distribution, and long mean residence time, compared with compound 7, and was slowly metabolized by human liver fractions. These findings suggest that the therapeutic effectiveness of an antimicrobial agent in the silkworms reflects appropriate pharmacokinetic properties.

UPLC-HR-MS/MS-based determination study on the metabolism of four synthetic cannabinoids, ADB-FUBICA, AB-FUBICA, AB-BICA and ADB-BICA, by human liver microsomes

Since 2012, several cannabimimetic indazole and indole derivatives with valine amino acid amide residue have emerged in the illicit drug market, and have gradually replaced the old generations of synthetic cannabinoids (SCs) with naphthyl or adamantine groups. Among them, ADB-FUBICA [N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-(4-fluorobenzyl)-1H-indole-3-carboxamide], AB-FUBICA [N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-(4-fluorobenzyl)-1H-indole-3-carboxamide], AB-BICA [N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-benzyl-1H-indole-3-carboxamide] and ADB-BICA [N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-benzyl-1H-indole-3-carboxamide] were detected in China recently, but unfortunately no information about their in vitro human metabolism is available. Therefore, biomonitoring studies to screen their consumption lack any information about the potential biomarkers (e.g. metabolites) to target. To bridge this gap, we investigated their phase I metabolism by incubating with human liver microsomes, and the metabolites were identified by ultra-performance liquid chromatography-high resolution-tandem mass spectrometry. Metabolites generated by N-dealkylation and hydroxylation on the 1-amino-alkyl moiety were found to be predominant for all these four substances, and others which underwent hydroxylation, amide hydrolysis and dehydrogenation were also observed in our investigation. Based on our research, we recommend that the N-dealkylation and hydroxylation metabolites are suitable and appropriate analytical markers for monitoring their intake.

Intoxication from the novel synthetic cannabinoids AB-PINACA and ADB-PINACA: A case series and review of the literature

Synthetic cannabinoids (SC), are a novel class of designer drugs which emerged as a drug of abuse in the late 2000's. We report a case series of 6 patients who may have smoked a synthetic cannabinoid product in a remote wilderness setting. They presented with varying degrees of altered mental status, agitation, and seizures. Two were confirmed to have AB-PINACA, ADB-PINACA and their respective pentanoic acid metabolites in biological specimens via liquid chromatography time-of-flight mass spectrometry (LC-TOF/MS). Both compounds had DEA Schedule I classification at the time of case presentation, and 22 SCs are currently temporary or permanent DEA Schedule I. More than 150 SCs are known to date, and new compounds are appearing at a rapid rate on darknet and surface web e-commerce websites, marketed as "research chemicals" or "legal highs." The scale and rapidity of SC evolution make legal control and analytical detection difficult. Nontargeted testing with liquid chromatography high resolution mass spectrometry (LC-HRMS), examining both parent compounds and metabolites, is the ideal method for novel SC identification and confirmation. Due to full agonism at the cannabinoid receptors CB1 and CB2, clinical effects are more severe than marijuana, which is a partial cannabinoid receptor agonist. They include agitated delirium, lethargy and coma, seizures, tachycardia, hypertension, and hallucinations, among other findings. Treatment is primarily symptomatic and aimed at airway protection and control of agitation and seizures. SCs do not appear to be abating anytime soon and require the cooperation of law enforcement, analytical scientists, and clinicians to adequately control. This article is part of the Special Issue entitled 'Designer Drugs and Legal Highs.'

Synthesis and Pharmacological Profiling of the Metabolites of Synthetic Cannabinoid Drugs APICA, STS-135, ADB-PINACA, and 5F-ADB-PINACA

Synthetic cannabinoids (SCs) containing a 1-pentyl-1-H substituted indole or indazole are abused around the world and are associated with an array of serious side effects. These compounds undergo extensive phase 1 metabolism after ingestion with little understanding whether these metabolites are contributing to the cannabimimetic activity of the drugs. This work presents the synthesis and pharmacological characterization of the major metabolites of two high concern SCs; APICA and ADB-PINACA. In a fluorometric assay of membrane potential, all metabolites that did not contain a carboxylic acid functionality retained potent activity at both the CB₁ (EC₅₀ = 14-787 nM) and CB₂ (EC₅₀ = 5.5-291 nM) receptors regardless of heterocyclic core or 3-carboxamide substituent. Of note were the 5-hydroxypentyl and 4-pentanone metabolites which showed significant increases in CB₂ functional selectivity. These results suggest that the metabolites of SCs potentially contribute to the overall pharmacological profile of these drugs.

Post-acquisition data mining techniques for LC–MS/MS-acquired data in drug metabolite identification

Metabolite identification is a crucial part of the drug discovery process. LC–MS/MS-based metabolite identification has gained widespread use, but the data acquired by the LC–MS/MS instrument is complex, and thus the interpretation of data becomes troublesome. Fortunately, advancements in data mining techniques have simplified the process of data interpretation with improved mass accuracy and provide a potentially selective, sensitive, accurate and comprehensive way for metabolite identification. In this review, we have discussed the targeted (extracted ion chromatogram, mass defect filter, product ion filter, neutral loss filter and isotope pattern filter) and untargeted (control sample comparison, background subtraction and metabolomic approaches) post-acquisition data mining techniques, which facilitate the drug metabolite identification. We have also discussed the importance of integrated data mining strategy.

Pharmaco-toxicological effects of the novel third-generation fluorinate synthetic cannabinoids, 5F-ADBINACA, AB-FUBINACA, and STS-135 in mice. In vitro and in vivo studies

INTRODUCTION

5F-ADBINACA, AB-FUBINACA, and STS-135 are 3 novel third-generation fluorinate synthetic cannabinoids that are illegally marketed as incense, herbal preparations, or research chemicals for their psychoactive cannabis-like effects.

METHODS

The present study aims at investigating the in vitro and in vivo pharmacological activity of 5F-ADBINACA, AB-FUBINACA, and STS-135 in male CD-1 mice, comparing their in vivo effects with those caused by the administration of Δ⁹ -THC and JWH-018. In vitro competition binding experiments revealed a nanomolar affinity and potency of the 5F-ADBINACA, AB-FUBINACA, and STS-135 on mouse and human CB₁ and CB₂ receptors. Moreover, these synthetic cannabinoids induced neurotoxicity in murine neuro-2a cells.

RESULTS

In vivo studies showed that 5F-ADBINACA, AB-FUBINACA, and STS-135 induced hypothermia; increased pain threshold to both noxious mechanical and thermal stimuli; caused catalepsy; reduced motor activity; impaired sensorimotor responses (visual, acoustic, and tactile); caused seizures, myoclonia, and hyperreflexia; and promoted aggressiveness in mice. Behavioral and neurological effects were fully prevented by the selective CB₁ receptor antagonist/inverse agonist AM 251. Differently, the visual sensory response induced by STS-135 was only partly prevented by the AM 251, suggesting a CB₁ -independent mechanism.

CONCLUSIONS

For the first time, the present study demonstrates the pharmaco-toxicological effects induced by the administration of 5F-ADBINACA, AB-FUBINACA, and STS-135 in mice and suggests their possible detrimental effects on human health.

Detection of the designer benzodiazepine metizolam in urine and preliminary data on its metabolism

Designer benzodiazepines provide an attractive alternative to prescribed benzodiazepines for abuse purposes as they are readily available via the Internet without control. Metizolam was ordered via the Internet and a 2 mg blue tablet was orally administered to a 54-year-old man. Urine samples were collected over 6 days in polypropylene tubes. After liquid/liquid extraction at pH 9.5, metizolam was analyzed by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS) using a standard method devoted to benzodiazepines, and ions transitions, at m/z 328.9 > 275.0 and 328.9 > 300.0. Metizolam was detectable in hydrolyzed urine during the 46-h period, with concentrations always lower than 11 ng/mL. About 0.3% of the initial dose was excreted in urines as total unchanged metizolam during the first 24 h. The most relevant potential CYP- and UGT-dependent metabolites of metizolam were investigated in vitro using human liver microsome incubation and, subsequently, liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UHPLC-Q-TOF-MS) analysis. Three mono-hydroxylated metabolites were produced including a hydroxylation compound at the 2-ethyl moiety of metizolam (M1) as quantitatively main metabolite, and a N-hydroxymetiazolam (M2). The structure of the third metabolite (M3) could not be elucidated because of a too low experimental production rate. Two authentic urine samples were analyzed using the same analytical method to search for metabolites of metizolam. M1, together with its glucuronide (M1-Glu), and M2 were observed in urine at the 8 h mark, whereas only M1 and M1-Glu were still detected in urine at 30 h post administration. Copyright © 2016 John Wiley & Sons, Ltd.

New psychoactive substances: an overview on recent publications on their toxicodynamics and toxicokinetics

This review article covers English-written and PubMed-listed review articles and original studies published between January 2015 and April 2016 dealing with the toxicodynamics and toxicokinetics of new psychoactive substances. Compounds covered include stimulants and entactogens, synthetic cannabinoids, tryptamines, NBOMes, phencyclidine-like drugs, benzodiazepines, and opioids. First, an overview and discussion is provided on timely review articles followed by an overview and discussion on recent original studies. Both sections are then concluded by an opinion on these latest developments. This review shows that the NPS market is still highly dynamic and that the data published on their toxicodynamics and toxicokinetics can hardly keep pace with the appearance of new entities. However, data available are very helpful to understand and predict how NPS may behave in severe intoxication. The currently best-documented parameter is the in vitro metabolism of NPS, a prerequisite to allow detection of NPS in biological matrices in cases of acute intoxications or chronic consumption. However, additional data such as their chronic toxicity are still lacking.

High-resolution mass spectrometry in toxicology: current status and future perspectives

This paper reviews high-resolution mass spectrometry (HRMS) approaches using time-of-flight or Orbitrap techniques for research and application in various toxicology fields, particularly in clinical toxicology and forensic toxicology published since 2013 and referenced in PubMed. In the introduction, an overview on applications of HRMS in various toxicology fields is given with reference to current review articles. Papers concerning HRMS in metabolism, screening, and quantification of pharmaceuticals, drugs of abuse, and toxins in human body samples are critically reviewed. Finally, a discussion on advantages as well as limitations and future perspectives of these methods is included.

Toxicokinetics of new psychoactive substances: plasma protein binding, metabolic stability, and human phase I metabolism of the synthetic cannabinoid WIN 55,212-2 studied using in vitro tools and LC-HR-MS/MS

The new psychoactive substance WIN 55,212-2 ((R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo-[1,2,3-de]-1,4-benzoxazin-6-yl]-1-napthalenylmethanone) is a potent synthetic cannabinoid receptor agonist. The metabolism of WIN 55,212-2 in man has never been reported. Therefore, the aim of this study was to identify the human in vitro metabolites of WIN 55,212-2 using pooled human liver microsomes and liquid chromatography-high resolution-tandem mass spectrometry (LC-HR-MS/MS) to provide targets for toxicological, doping, and environmental screening procedures. Moreover, a metabolic stability study in pooled human liver microsomes (pHLM) was carried out. In total, 19 metabolites were identified and the following partly overlapping metabolic steps were deduced: degradation of the morpholine ring via hydroxylation, N- and O-dealkylation, and oxidative deamination, hydroxylations on either the naphthalene or morpholine ring or the alkyl spacer with subsequent oxidation, epoxide formation with subsequent hydrolysis, or combinations. In conclusion, WIN 55,212-2 was extensively metabolized in human liver microsomes incubations and the calculated hepatic clearance was comparably high, indicating a fast and nearly complete metabolism in vivo. This is in line with previous findings on other synthetic cannabinoids. Copyright © 2016 John Wiley & Sons, Ltd.

CYP3A4 Mediates Oxidative Metabolism of the Synthetic Cannabinoid AKB-48

Synthetic cannabinoid designer drugs have emerged as drugs of abuse during the last decade, and acute intoxication cases are documented in the scientific literature. Synthetic cannabinoids are extensively metabolized, but our knowledge of the involved enzymes is limited. Here, we investigated the metabolism of N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide (AKB-48), a compound identified in herbal blends from 2012 and onwards. We screened for metabolite formation using a panel of nine recombinant cytochrome P450 (CYP) enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) and compared the formed metabolites to human liver microsomal (HLM) incubations with specific inhibitors against CYP2D6, 2C19, and 3A4, respectively. The data reported here demonstrate CYP3A4 to be the major CYP enzyme responsible for the oxidative metabolism of AKB-48, preferentially performing the oxidation on the adamantyl moiety. Genetic polymorphisms are likely not important with regard to toxicity given the major involvement of CYP3A4. Adverse drug-drug interactions (DDIs) could potentially occur in cases with co-intake of strong CYP3A4 inhibitors, e.g., HIV antivirals and azole antifungal agents.

Identification of AKB-48 and 5F-AKB-48 Metabolites in Authentic Human Urine Samples Using Human Liver Microsomes and Time of Flight Mass Spectrometry

The occurrence of structurally related synthetic cannabinoids makes the identification of unique markers of drug intake particularly challenging. The aim of this study was to identify unique and abundant metabolites of AKB-48 and 5F-AKB-48 for toxicological screening in urine. Investigations of authentic urine samples from forensic cases in combination with human liver microsome (HLM) experiments were used for identification of metabolites. HLM incubations of AKB-48 and 5F-AKB-48 along with 35 urine samples from authentic cases were analyzed with liquid chromatography quadrupole tandem time of flight mass spectrometry. Using HLMs 41 metabolites of AKB-48 and 37 metabolites of 5F-AKB-48 were identified, principally represented by hydroxylation but also ketone formation and dealkylation. Monohydroxylated metabolites were replaced by di- and trihydroxylated metabolites within 30 min. The metabolites from the HLM incubations accounted for on average 84% (range, 67-100) and 91% (range, 71-100) of the combined area in the case samples for AKB-48 and 5F-AKB-48, respectively. While defluorinated metabolites accounted for on average 74% of the combined area after a 5F-AKB-48 intake only a few identified metabolites were shared between AKB-48 and 5F-AKB-48, illustrating the need for a systematic approach to identify unique metabolites. HLMs in combination with case samples seem suitable for this purpose.

Pentylindole/Pentylindazole Synthetic Cannabinoids and Their 5-Fluoro Analogs Produce Different Primary Metabolites: Metabolite Profiling for AB-PINACA and 5F-AB-PINACA

Whereas non-fluoropentylindole/indazole synthetic cannabinoids appear to be metabolized preferably at the pentyl chain though without clear preference for one specific position, their 5-fluoro analogs' major metabolites usually are 5-hydroxypentyl and pentanoic acid metabolites. We determined metabolic stability and metabolites of N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-pentyl-1H-indazole-3-carboxamide (AB-PINACA) and 5-fluoro-AB-PINACA (5F-AB-PINACA), two new synthetic cannabinoids, and investigated if results were similar. In silico prediction was performed with MetaSite (Molecular Discovery). For metabolic stability, 1 μmol/L of each compound was incubated with human liver microsomes for up to 1 h, and for metabolite profiling, 10 μmol/L was incubated with pooled human hepatocytes for up to 3 h. Also, authentic urine specimens from AB-PINACA cases were hydrolyzed and extracted. All samples were analyzed by liquid chromatography high-resolution mass spectrometry on a TripleTOF 5600+ (AB SCIEX) with gradient elution (0.1% formic acid in water and acetonitrile). High-resolution full-scan mass spectrometry (MS) and information-dependent acquisition MS/MS data were analyzed with MetabolitePilot (AB SCIEX) using different data processing algorithms. Both drugs had intermediate clearance. We identified 23 AB-PINACA metabolites, generated by carboxamide hydrolysis, hydroxylation, ketone formation, carboxylation, epoxide formation with subsequent hydrolysis, or reaction combinations. We identified 18 5F-AB-PINACA metabolites, generated by the same biotransformations and oxidative defluorination producing 5-hydroxypentyl and pentanoic acid metabolites shared with AB-PINACA. Authentic urine specimens documented presence of these metabolites. AB-PINACA and 5F-AB-PINACA produced suggested metabolite patterns. AB-PINACA was predominantly hydrolyzed to AB-PINACA carboxylic acid, carbonyl-AB-PINACA, and hydroxypentyl AB-PINACA, likely in 4-position. The most intense 5F-AB-PINACA metabolites were AB-PINACA pentanoic acid and 5-hydroxypentyl-AB-PINACA.

Synthetic cannabinoids pharmacokinetics and detection methods in biological matrices

Synthetic cannabinoids (SC), originally developed as research tools, are now highly abused novel psychoactive substances. We present a comprehensive systematic review covering in vivo and in vitro animal and human pharmacokinetics and analytical methods for identifying SC and their metabolites in biological matrices. Of two main phases of SC research, the first investigated therapeutic applications, and the second abuse-related issues. Administration studies showed high lipophilicity and distribution into brain and fat tissue. Metabolite profiling studies, mostly with human liver microsomes and human hepatocytes, structurally elucidated metabolites and identified suitable SC markers. In general, SC underwent hydroxylation at various molecular sites, defluorination of fluorinated analogs and phase II metabolites were almost exclusively glucuronides. Analytical methods are critical for documenting intake, with different strategies applied to adequately address the continuous emergence of new compounds. Immunoassays have different cross-reactivities for different SC classes, but cannot keep pace with changing analyte targets. Gas chromatography and liquid chromatography mass spectrometry assays - first for a few, then numerous analytes - are available but constrained by reference standard availability, and must be continuously updated and revalidated. In blood and oral fluid, parent compounds are frequently present, albeit in low concentrations; for urinary detection, metabolites must be identified and interpretation is complex due to shared metabolic pathways. A new approach is non-targeted HRMS screening that is more flexible and permits retrospective data analysis. We suggest that streamlined assessment of new SC's pharmacokinetics and advanced HRMS screening provide a promising strategy to maintain relevant assays.

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.

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.