Designer benzodiazepine rat pharmacokinetics: A comparison of alprazolam, flualprazolam and flubromazolam.

Designer benzodiazepines, including flualprazolam and flubromazolam, are clandestinely produced to circumvent federal regulations. Although flualprazolam and flubromazolam are structurally similar to alprazolam, they do not have an approved medical indication. Flualprazolam differs from alprazolam by the addition of a single fluorine atom. Whereas, flubromazolam differs by the addition of a single fluorine atom and substitution of a bromine for a chlorine atom. The pharmacokinetics of these designer compounds have not been extensively evaluated. In the present study, we evaluated flualprazolam and flubromazolam in a rat model and compared the pharmacokinetics of both compounds to alprazolam. Twelve male, Sprague-Dawley rats were given a 2 mg/kg subcutaneous dose of alprazolam, flualprazolam and flubromazolam and plasma pharmacokinetic parameters were evaluated. Both compounds displayed significant two-fold increases in volume of distribution and clearance. Additionally, flualprazolam displayed a significant increase in half-life leading to a nearly double half-life when compared to alprazolam. The findings of this study demonstrate that fluorination of the alprazolam pharmacophore increases pharmacokinetic parameters including half-life and volume of distribution. The increase in these parameters for flualprazolam and flubromazolam leads to an overall increased exposure in the body and a potential for greater toxicity than alprazolam.

Flubromazolam-Derived Designer Benzodiazepines: Toxicokinetics and Analytical Toxicology of Clobromazolam and Bromazolam.

Flubromazolam is widely known as highly potent designer benzodiazepine (DBZD). Recently, the two flubromazolam-derived new psychoactive substances (NPS) clobromazolam and bromazolam appeared on the drugs of abuse market. Since no information concerning their toxicokinetics in humans is available, the aims of the current study were to elucidate their metabolic profile and to identify the isozymes involved in their phase I and phase II metabolism. In vitro incubations with pooled human liver S9 fraction were performed and analyzed by liquid chromatography coupled to orbitrap-based high-resolution tandem mass spectrometry (LC-HRMS-MS). Biosamples after the ingestion of bromazolam allowed the identification of metabolites in human plasma and urine as well as the determination of bromazolam plasma concentrations by LC-HRMS-MS using the standard addition method. In total, eight clobromazolam metabolites were identified in vitro as well as eight bromazolam metabolites in vitro and in vivo. Predominant metabolic steps were hydroxylation, glucuronidation and combinations thereof. Alpha-hydroxy bromazolam glucuronide and bromazolam N-glucuronide are recommended as screening targets in urine. Bromazolam and its alpha-hydroxy metabolite are recommended if conjugate cleavage is part of the sample preparation procedure. The bromazolam plasma concentrations were determined to be 6 and 29 µg/L, respectively. Several cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT) isozymes were shown to catalyze their metabolic transformations. CYP3A4 was involved in the formation of all phase I metabolites of both NPS, while UGT1A4 and UGT2B10 catalyzed their N-glucuronidation. Several UGT isoforms catalyzed the glucuronidation of the hydroxy metabolites. In conclusion, the determined bromazolam plasma concentrations in the low micrograms per liter range underlined the need for sensitive analytical methods and the importance of suitable urine screening procedures including DBZD metabolites as targets. Such an analytical strategy should be also applicable for clobromazolam.

From a Designer Drug to the Discovery of Selective Cannabinoid Type 2 Receptor Agonists with Favorable Pharmacokinetic Profiles for the Treatment of Systemic Sclerosis.

Synthetic cannabinoids, as exemplified by SDB-001 (1), bind to both CB1 and CB2 receptors and exert cannabimimetic effects similar to (-)-trans-Δ9-tetrahydrocannabinol, the main psychoactive component present in the cannabis plant. As CB1 receptor ligands were found to have severe adverse psychiatric effects, increased attention was turned to exploiting the potential therapeutic value of the CB2 receptor. In our efforts to discover novel and selective CB2 receptor agonists, 1 was selected as a starting point for hit molecule identification and a class of 1H-pyrazole-3-carboxamide derivatives were thus designed, synthesized, and biologically evaluated. Systematic structure-activity relationship investigations resulted in the identification of the most promising compound 66 as a selective CB2 receptor agonist with favorable pharmacokinetic profiles. Especially, 66 treatment significantly attenuated dermal inflammation and fibrosis in a bleomycin-induced mouse model of systemic sclerosis, supporting that CB2 receptor agonists might serve as potential therapeutics for treating systemic sclerosis.

The neurobehavioral effects of the designer drug naphyrone - an experimental investigation with pharmacokinetics and concentration/effect relationship in mice.

RATIONALE: The recreational use of naphyrone, a potent synthetic cathinone with a pyrovalerone structure, has raised questions about possible deleterious neurobehavioral consequences. OBJECTIVE: To investigate naphyrone-induced neurobehavioral effects and alterations in brain monoamines using two patterns of abuse, i.e., single and repeated (binge) use. METHODS: We studied naphyrone dose/induced locomotor activity relationship at 3, 10, 30, and 100 mg/kg in mice. We investigated the effects of single (30 mg/kg; acute injection) versus repeated (30 mg/kg ×3/day for 3 days; binge injection) intraperitoneal naphyrone administration on locomotor activity, anxiety-like behavior, spatial recognition memory, anhedonia, behavioral despair, and social interaction. We measured post-mortem prefrontal cortex levels of monoamines and modeled naphyrone pharmacokinetics and concentration/locomotor effect relationship. RESULTS: Both naphyrone administration patterns induced time-dependent increases in locomotor activity (p < 0.001 and p < 0.0001, respectively) and social interaction (p < 0.05 and p < 0.001, respectively) but did not alter spatial recognition memory or anhedonia. Acute naphyrone injection induced anxiety-like behavior (p < 0.01) and reduced resignation (p < 0.01) whereas binge administration induced non-anxiety-like behavior (p < 0.05) and did not alter behavioral despair. Both patterns increased the prefrontal cortex dopamine (p < 0.0001) and norepinephrine (p < 0.05 and p < 0.01, respectively) but not serotonin content. Naphyrone pharmacokinetics followed a two-compartment model with an overall elimination half-life of 0.3 h. The naphyrone concentration/locomotor effect relationship was described by an additive Emax model with an EC50 of 672 µg/L. CONCLUSIONS: Single naphyrone administration increases locomotor activity according to a direct concentration/effect relationship. The neurobehavioral effects after binge differs from those after single administration and are not explained by drug accumulation given the relatively fast elimination.

3,4-Methylenedioxypyrovalerone: Neuropharmacological Impact of a Designer Stimulant of Abuse on Monoamine Transporters.

Methylenedioxypyrovalerone (MDPV) is an abused synthetic cathinone, commonly referred to as a "bath salt." Because the dopamine (DA) transporter (DAT) and vesicular monoamine transporter-2 (VMAT-2) are key regulators of both the abuse and neurotoxic potential of structurally and behaviorally related agents, the impact of MDPV on these transporters was investigated. Results revealed that a single in vivo MDPV administration rapidly (within 1 hour) and reversibly increased both rat striatal DAT and VMAT-2 activity, as assessed via [3H]DA uptake in synaptosomes and synaptic vesicles, respectively, prepared from treated rats. There was no evidence of an MDPV-induced increase in plasmalemmal membrane DAT surface expression. Plasma concentrations of MDPV increased dose-dependently as assessed 1 hour after 2.5 and 5.0 mg/kg (s.c.) administration and returned to levels less than 10 ng/ml by 18 hours after 2.5 mg/kg (s.c.). Neither pretreatment with a D1 receptor (SCH23390), a D2 receptor (eticlopride), nor a nicotinic receptor (mecamylamine) antagonist attenuated the MDPV-induced increase in DAT activity. In contrast, eticlopride pretreatment attenuated both the MDPV-induced increase in VMAT-2-mediated DA uptake and an associated increase in cytoplasmic-associated vesicle VMAT-2 immunoreactivity. SCH23390 did not attenuate the MDPV-induced increase in VMAT-2 activity. Repeated MDPV injections did not cause persistent DAergic deficits, as assessed 7 to 8 days later. The impact of MDPV on striatal and hippocampal serotonergic assessments was minimal. Taken together, these data contribute to a growing pharmacological rubric for evaluating the ever-growing list of designer cathinone-related stimulants. The profile of MDPV compared with related psychostimulants is discussed. SIGNIFICANCE STATEMENT: Pharmacological characterization of the synthetic cathinone, 3,4-methylenedioxypyrovalerone (MDPV; commonly referred to as a "bath salt"), is critical for understanding the abuse liability and neurotoxic potential of this and related agents. Accordingly, the impact of MDPV on monoaminergic neurons is described and compared with that of related psychostimulants.

Analysis of 4-fluoroamphetamine in cerumen after controlled oral application.

Cerumen was found to be a promising alternative specimen for the detection of drugs. In a pilot study, drugs of abuse were identified at a higher detection rate and a longer detection window in cerumen than in urine. In this study, cerumen from subjects was analyzed after they ingested the designer stimulant 4-fluoroamphetamine (4-FA) in a controlled manner. METHODS: Twelve subjects ingested placebo and 100 mg of 4-FA. Five of them were also given 150 mg of 4-FA in 150 mL Royal Club bitter lemon drink at least after 7 days. Cerumen was sampled using cotton swabs at baseline, 1 h after the ingestion of the drug and at the end of the study day (12 h). After extraction with ethyl acetate followed by solid-phase extraction, the extracts were analyzed using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). RESULTS AND DISCUSSION: In the cerumen of all 12 subjects, 4-FA was detected 12 h after its ingestion; in most subjects, cerumen was detected after 1 h of ingestion, ranging from 0.06 to 13.90 (median 1.52) ng per swab. The detection of 4-FA in cerumen sampled 7 days or more after the first dose suggested a long detection window of cerumen. CONCLUSIONS: Cerumen can be successfully used to detect a single drug ingestion even immediately after the ingestion when a sufficient amount of cerumen is used.

Determination of synthetic cathinone α-pyrrolidinovalero-phenone and its metabolite in urine using solid-phase extraction and gas chromatography-mass spectrometry.

RATIONALE: The presence of α-pyrrolidinovalerophenone (α-PVP) and its metabolites in urine is evidence of the administration of α-PVP. A toxicological challenge is that the metabolites of α-PVP exhibit amphoteric properties, which make them unsuitable for detection using gas chromatography-mass spectrometry (GC/MS). In the study reported, proper derivatization and sample extraction were essential for improving the sensitivity for GC/MS analysis. METHODS: An automated solid-phase extraction (SPE) method has been developed and optimized. The derivatization efficiency was tested using longer reaction time and the addition of polar pyridine into a mixture of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane. Method validation, including linearity, limit of detection, precision, accuracy, and recovery, was evaluated using automatic SPE and GC/MS. RESULTS: The results suggested that adding pyridine to BSTFA (1:1, v/v) significantly improved derivatization efficiency and precision. After optimization, the linear range was from 25 to 1000 ng mL-1 with R2 > 0.9950. The limit of detection was 5 ng mL-1 for α-PVP and 25 ng mL-1 for OH-α-PVP. The recovery for SPE was over 88%. The inter-day and intra-day precisions were less than 15%. A forensic sample has been found containing α-PVP (67.3 ng mL-1 ) and OH-α-PVP (560.2 ng mL-1 ). CONCLUSIONS: This study is the first to validate an auto-SPE-GC/MS method for the quantification and qualification of α-PVP and OH-α-PVP in urine. We have successfully improved the derivatization efficiency and developed a sensitive and semi-automatic approach. This approach is desirable for the detection of synthetic cathinone at trace levels in biological samples.

The metabolic fate of two new psychoactive substances - 2-aminoindane and N-methyl-2-aminoindane - studied in vitro and in vivo to support drug testing.

The aim of this study was to characterize the in vitro and in vivo metabolism of 2-aminoindane (2,3-dihydro-1H-inden-2-amine, 2-AI), and N-methyl-2-aminoindane (N-methyl-2,3-dihydro-1H-inden-2-amine, NM-2-AI) after incubations using pooled human liver microsomes (pHLMs), pooled human liver S9 fraction (pS9), and rat urine after oral administration. After analysis using liquid chromatography coupled to high-resolution mass spectrometry, pHLM incubations revealed that 2-AI was left unmetabolized, while NM-2-AI formed a hydroxylamine and diastereomers of a metabolite formed after hydroxylation in beta position. Incubations using pS9 led to the formation of an acetyl conjugation in the case of 2-AI and merely a hydroxylamine for NM-2-AI. Investigations on rat urine showed that 2-AI was hydroxylated also forming diasteromers as described for NM-2-AI or acetylated similar to incubations using pS9. All hydroxylated metabolites of NM-2-AI except the hydroxylamine were found in rat urine as additional sulfates. Assuming similar patterns in humans, urine screening procedures might be focused on the parent compounds but should also include their metabolites. An activity screening using human recombinant N-acetyl transferase (NAT) isoforms 1 and 2 revealed that 2-AI was acetylated exclusively by NAT2, which is polymorphically expressed.

Organ distribution of diclazepam, pyrazolam and 3-fluorophenmetrazine.

The organ distribution of 3-fluorophenmetrazine (3-FPM), pyrazolam, diclazepam as well as its main metabolites delorazepam, lormetazepam and lorazepam, was investigated. A solid phase extraction (SPE) and a QuEChERS (acronym for quick, easy, cheap, effective, rugged and safe) - approach were used for the extraction of the analytes from human tissues, body fluids and stomach contents. The detection was performed on a liquid chromatography-tandem mass spectrometry system (LCMS/MS). The analytes of interest were detected in all body fluids and tissues. Results showed femoral blood concentrations of 10 µg/L for 3-FPM, 28 µg/L for pyrazolam, 1 µg/L for diclazepam, 100 µg/L for delorazepam, 6 µg/L for lormetazepam, and 22 µg/L for lorazepam. Tissues (muscle, kidney and liver) and bile exhibited higher concentrations of the mentioned analytes than in blood. Additional positive findings in femoral blood were for 2-fluoroamphetamine (2-FA, approx. 89 µg/L), 2-flourometamphetamine (2-FMA, hint), methiopropamine (approx. 2.2 µg/L), amphetamine (approx. 21 µg/L) and caffeine (positive). Delorazepam showed the highest ratio of heart (C) and femoral blood (P) concentration (C/P ratio = 2.5), supported by the concentrations detected in psoas muscle (430 µg/kg) and stomach content (approx. 210 µg/L, absolute 84 µg). The C/P ratio indicates that delorazepam displays susceptibility for post-mortem redistribution (PMR), supported by the findings in muscle tissue. 3-FPM, pyrazolam, diclazepam, lorazepam and lormetazepam did apparently not exhibit any PMR. The cause of death, in conjunction with autopsy findings was concluded as a positional asphyxia promoted by poly-drug intoxication by arising from designer benzodiazepines and the presence of synthetic stimulants.

Toxicokinetics and analytical toxicology of the abused opioid U-48800 - in vitro metabolism, metabolic stability, isozyme mapping, and plasma protein binding.

Due to the risk of new synthetic opioids (NSOs) for human health, the knowledge of their toxicokinetic characteristics is important for clinical and forensic toxicology. U-48800 is an NSO structurally non-related to classical opioids such as morphine or fentanyl and offered for abuse. As toxicokinetic data of U-48800 is not currently available, the aims of this study were to identify the in vitro metabolites of U-48800 in pooled human liver S9 fraction (pS9), to map the isozymes involved in the initial metabolic steps, and to determine further toxicokinetic data such as metabolic stability, including the in vitro half-life (t1/2 ), and the intrinsic (CLint ) and hepatic clearance (CLh ). Furthermore, drug detectability studies in rat urine should be done using hyphenated mass spectrometry. In total, 13 phase I metabolites and one phase II metabolite were identified. N-Dealkylation, hydroxylation, and their combinations were the predominant metabolic reactions. The isozymes CYP2C19 and CYP3A4 were mainly involved in these initial steps. CYP2C19 poor metabolizers may suffer from an increased U-48800 toxicity. The in vitro t1/2 and CLint could be rated as moderate, compared to structural related compounds. After administration of an assumed consumer dose to rats, the unchanged parent compound was found only in very low abundance but three metabolites were detected additionally. Due to species differences, metabolites found in rats might be different from those in humans. However, phase I metabolites found in rat urine, the parent compound, and additionally the N-demethyl metabolite should be used as main targets in toxicological urine screening approaches.

Phenethylamine-derived new psychoactive substances 2C-E-FLY, 2C-EF-FLY, and 2C-T-7-FLY: Investigations on their metabolic fate including isoenzyme activities and their toxicological detectability in urine screenings.

Psychoactive substances of the 2C-series are phenethylamine-based designer drugs that can induce psychostimulant and hallucinogenic effects. The so-called 2C-FLY series contains rigidified methoxy groups integrated in a 2,3,6,7-tetrahydrobenzo[1,2-b:4,5-b']difuran core. The aim of the presented work was to investigate the in vivo and in vitro metabolic fate including isoenzyme activities and toxicological detectability of the three new psychoactive substances (NPS) 2C-E-FLY, 2C-EF-FLY, and 2C-T-7-FLY to allow clinical and forensic toxicologists the identification of these novel compounds. Rat urine, after oral administration, and pooled human liver S9 fraction (pS9) incubations were analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS). By performing activity screenings, the human isoenzymes involved were identified and toxicological detectability in rat urine investigated using standard urine screening approaches (SUSAs) based on gas chromatography (GC)-MS, LC-MSn , and LC-HRMS/MS. In total, 32 metabolites were tentatively identified. Main metabolic steps consisted of hydroxylation and N-acetylation. Phase I metabolic reactions were catalyzed by CYP2D6, 3A4, and FMO3 and N-acetylation by NAT1 and NAT2. Methoxyamine was used as a trapping agent for detection of the deaminated metabolite formed by MAO-A and B. Interindividual differences in the metabolism of the 2C-FLY drugs could be caused by polymorphisms of enzymes involved or drug-drug interactions. All three SUSAs were shown to be suitable to detect an intake of these NPS but common metabolites of 2C-E-FLY and 2C-EF-FLY have to be considered during interpretation of analytical findings.

LC-MS/MS analysis of two new designer drugs (FLY serie) in rat plasma and its application to a pharmacokinetic study.

The widespread diffusion of new psychoactive substances, requires a continuous update and development of new methods able to identify and quantify these new molecules in biological matrices. In this study an analytical method for the determination of two new benzodifuranyl derivatives, 1-(2,3,6,7-tetrahydrofuro[2,3-f][1]benzofuran-4-yl)propan-2-amine and 2-(2,3,6,7-tetrahydrofuro[2,3-f][1]benzofuran-4-yl)ethanamine, in rat plasma was developed. A solid phase extraction using C18 cartridges was carried out obtaining good recoveries with low matrix effect. Quantification was performed by a liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Separation was carried out on a C18 reverse phase column with water/methanol containing 0.1% of formic acid as mobile phase. These conditions allowed to achieve adequate separation, resolution and signal-to-noise ratio for analytes and internal standard. Calibration curves were linear over the concentration range from 10 to 400 ng/ml with correlation coefficients that exceeded 0.995. Obtained precision, accuracy and recovery showed good reproducibility and selectivity. Finally, the validation method was successfully applied to an in vivo study in order to evaluate the pharmacokinetic profile of these new amphetamines.

Pharmacokinetic properties of 4-fluoroamphetamine in serum and oral fluid after oral ingestion.

INTRODUCTION: Each year, synthetic drugs occur in high numbers on the illicit drug market. But data on their pharmacology and toxicology are scarce. Therefore, a controlled study was performed to evaluate pharmacokinetic parameters of 4-fluoroamphetamine (4-FA) in humans and to compare it with effects. METHODS: Twelve subjects ingested 100 mg and five subjects also received 150 mg 4-FA in a bitter lemon drink. Blood and oral fluid samples were taken during the following 12 hours and analyzed for 4-FA and traces of amphetamine as impurity by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: For 12 hours after ingestion, the concentration-time course of 4-FA was similar to that of amphetamine with maximal concentrations appearing in serum after about 2 hours (in median 195 ng/mL after the 100 mg dose, range 155-316 ng/mL). The elimination half-life was approximately 8-9 hours and shorter than that of amphetamine but it exhibited a marked variation (5.5-16.8 hours). In oral fluid, 4-FA could also be detected for 12 hours and concentrations were higher than in serum. During the first 3 hours after ingestion concentrations were higher, most probably due to oral contamination. Serum concentrations in forensic cases were in the range of those observed in the present study suggesting dosages in recreational use in the range of those tested here. CONCLUSIONS: The pharmacokinetic properties of 4-FA are similar to that of amphetamine including a marked variation in elimination. However, recreational dosages may already exhibit prominent adverse effects and may even have life-threatening consequences.

Method validation and preliminary pharmacokinetic studies on the new designer stimulant 3-fluorophenmetrazine (3-FPM).

Pharmaceutical research not only provides the basis for the development of new medicinal products but also for the synthesis of new drugs of abuse. 3-Fluorophenmetrazine (3-FPM), a fluorinated derivative of the anorectic phenmetrazine, was first patented in 2011 and appeared on the drug market in 2014. Though invented for potential medical purposes, pharmacokinetic data on this compound, crucial for interpreting forensic as well as clinical cases, are not available. Therefore, a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method for the detection of 3-FPM in serum, urine, and oral fluid was developed, validated for urine and serum, and used to quantify 3-FPM in samples obtained during a controlled self-experiment. The method proved to be linear, selective and sufficiently sensitive. The limits of detection (LODs) were 0.1 ng/mL, 0.2 ng/mL, and 0.05 ng/mL in serum, urine, and oral fluid. Inter-day precision and intra-day precision (RSD) in serum samples were below 6.3% and below 8.5%, respectively. The highest serum concentration (cmax ) of 210 ng/mL was reached 2.5 hours (tmax ) after ingestion. The elimination half-life and the volume of distribution were calculated to be approx. 8.8 hours and 400 L (5.3 L/kg). 3-FPM could be detected in serum and urine up to 82 hours and 116 hours, respectively. It was still detected in the last oral fluid sample taken 55 hours after ingestion. 3-FPM was mainly excreted unchanged. Main metabolic reactions were aryl-hydroxylation and N-hydroxylation. Interestingly, the product of oxidative ring opening (2-amino-1-(3-fluorophenyl)propan-1-ol) showed the largest window of detection in the self-experiment.

An expanding world of new psychoactive substances-designer benzodiazepines.

The abuse of new psychoactive substances (NPS) has been increasing dramatically since the late 2000s worldwide. Between 2009 and 2017, a total of 803 individual NPS were reported to the United Nations Office of Drugs and Crime by 111 countries and territories. Although the most popular compounds are synthetic cannabinomimetics and psychostimulatory derivatives of cathinone (so-called ß-keto-amphetamines), novel benzodiazepines have recently emerged on the recreational drug market. The misuse/abuse of "designer benzodiazepines" (DBZD), a common name for the benzodiazepine class NPS, has become an increasing problem in many countries. The DBZD group includes pharmaceutical drug candidates that have never been approved for medical use, compounds that were synthesized by a simple structural modification of a registered drug, and some active metabolites of registered benzodiazepines. This survey presents members of the DBZD group, describes the epidemiological trends and clinical effects associated with DBZD use, and discusses available data on their metabolism. Special emphasis is given to cases of intoxications involving these compounds.

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%).

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

Designer benzodiazepines have emerged as recreational drugs. They are available via the Internet without control and are found in the form of falsified (fake) medicines. For some of them, limited information concerning their effects, their toxicity, and their detection in bio fluids is available in the literature. For others, nothing has been published, as in the case of flunitrazolam (FNTZ). To gain preliminary data on its elimination parameters in urine and to investigate its metabolism, one of the authors ingested one pink tablet bought on the Internet, after confirming the absence of other compounds and agreement with the labeled dosage (0.25 mg) by nuclear magnetic resonance (NMR). A software algorithm (MetaboLynx, Waters, Milford, MA, USA) was used to predict FNTZ biotransformation and four potential metabolites were proposed: 4-hydroxy-FNTZ, desnitro-FNTZ, 7-amino-FNTZ, and 7-acetamido-FNTZ. Urine samples were collected over 72 hours following oral administration of one tablet. After liquid/liquid extraction at pH 9.5, FNTZ concentrations were determined using ultra performance liquid chromatography-triple quadrupole-mass spectrometry (UPLC-QqQ-MS/MS). FNTZ remained detectable in hydrolyzed urine for 21 hours after ingestion, with concentrations ranging between 1 and 18 ng/mL. About 3% of the initial dose was excreted in urine as total unchanged FNTZ during this period. In vitro experiments (HLM incubations) were performed using ultra performance liquid chromatography-quadrupole time of flight-mass spectrometry (UPLC-QTOF-MS) in order to investigate the potential CYP- and UGT-dependent metabolites where only 7-amino-FNTZ was detected as the only metabolite. However, in the urine specimens, desnitro-FNTZ, 7-acetamido-FNTZ and 7-amino-FNTZ were the main detected compounds. The identification of FNTZ metabolites dramatically improves the detection windows of the drug up to 37 hours.

The Evolving Landscape of Designer Drugs.

Since 2008 there has been an onslaught of new drugs in the illicit marketplace. Often referred to as "research chemicals," "designer drugs," or "novel psychoactive substances" (NPS), these substances are used for their pharmacological effects which are often similar to more widely known drugs such as ecstasy or heroin. In some cases users specifically seek out these new chemicals, in other cases they are simply purchasing what they believe to be their normal drug of choice from a dealer, but the product is not what it is purported to be. Implementation of national and international systems to monitor the appearance of new compounds enables laboratories to be prepared with validated tests to detect them in biological specimens. The most common classes of NPS are synthetic cannabinoids, novel opioids, novel benzodiazepines, stimulants, and hallucinogens. Within these groups the compounds may be drugs that were originally synthesized for research purposes during the pursuit of new therapeutic agents such as the synthetic cannabinoid JWH-018 and the designer opioid U47700. Others like etizolam are compounds used in other countries but not commonly seen in the USA. Some are drugs synthesized specifically to circumvent legal controls. In all cases, these compounds present a unique challenge to forensic toxicology laboratories which must quickly develop and validate analytical methods for the identification and quantification in biological matrices.This chapter is a condensed and updated version of an article originally published in Clinical and Forensic Toxicology News.

A review of the influence of functional group modifications to the core scaffold of synthetic cathinones on drug pharmacokinetics.

RATIONALE: The synthetic cathinones are a class of designer drugs of abuse that share a common core scaffold. The pharmacokinetic profiles of the synthetic cathinones vary based on the substitutions to the core scaffold. OBJECTIVES: To provide a summary of the literature regarding the pharmacokinetic characteristics of the synthetic cathinones, with a focus on the impact of the structural modifications to the pharmacokinetics. RESULTS: In many, but not all, instances the pharmacokinetic characteristics of the synthetic cathinones can be reasonably predicted based on the substitutions to the core scaffold. Mephedrone and methylone are chemically alike and have similar Tmax and t1/2 in male rats. MDPV, a structurally distinct synthetic cathinone from mephedrone and methylone, has a lower Tmax and t1/2. Increasing the length of the alkyl chain on the α position of methylone, to produce pentylone, results in increased plasma concentrations and longer t1/2. Metabolism of the synthetic cathinones is reasonably predictable based on the chemical structure, and several phase I metabolites retain pharmacodynamic activity. CYP2D6 is implicated in the metabolism of all of the synthetic cathinones, and other P450s (CYP1A2, CYP2B6, and CYP2C19) are known to contribute variably to the metabolism of specific synthetic cathinones. CONCLUSIONS: Continued research will lead to a better understanding of the pharmacokinetic changes associated with structural modifications to the cathinone scaffold, and potentially in the long range, enhanced overdose and addiction therapy. Additionally, the areas of polydrug use and pharmacogenetics have been largely overlooked with regard to synthetic cathinones.