Pharmacological and biotransformation studies of 1-acyl-substituted derivatives of d-lysergic acid diethylamide (LSD)

Analytical and behavioral characterization of 1-hexanoyl-LSD (1H-LSD)

The development of lysergic acid diethylamide (LSD) derivatives and analogs continues to inform the design of novel receptor probes and potentially new medicines. On the other hand, a number of newly developed LSD derivatives have also emerged as recreational drugs, leading to reports of their detection in some countries. One position in the ergoline scaffold of LSD that is frequently targeted is the N1-position; numerous N1-alkylcarbonyl LSD derivatives have been reported where the acyl chain is attached to the indole nitrogen, for example, in the form of linear n-alkane substituents, which represent higher homologs of the prototypical 1-acetyl-N,N-diethyllysergamide (1A-LSD, ALD-52). In this study, 1-hexanoyl-LSD (1H-LSD, SYN-L-027), a novel N1-acyl LSD derivative, was characterized analytically using standard techniques, followed by evaluation of its in vivo behavioral effects using the mouse head-twitch response (HTR) assay in C57BL/6J mice. 1H-LSD induced the HTR, with a median effective dose (ED50) of 192.4 μg/kg (equivalent to 387 nmol/kg), making it roughly equipotent to ALD-52 when tested previously under similar conditions. Similar to other N1-acylated analogs, 1H-LSD is anticipated to by hydrolyzed to LSD in vivo and acts as a prodrug. It is currently unknown whether 1H-LSD has appeared as on the research chemical market or is being used recreationally.

Modification of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method targeting lysergic acid diethylamide (LSD) and its primary metabolite (OH-LSD) to include nine LSD analogs

A variety of LSD analogs have emerged in recent years with dual purposes of avoiding prosecution from possession while providing new options for those willing to experiment with hallucinogenic drugs. In this study, a previously published automated sample preparation method for LSD and its primary metabolite (OH-LSD) was utilized to extract LSD, OH-LSD, and nine LSD analogs from urine. The liquid chromatography tandem mass spectrometry (LC-MS/MS) method was modified from the previously published LC conditions to utilize a different analytical column and gradient elution program. Mobile phases of 10 mM ammonium formate with 0.1% formic acid in deionized water (mobile phase A) and 0.1% formic acid in methanol (mobile phase B) were employed. The method was validated to ANSI/ASB Standard 036 with a 0.1 ng/mL limit of detection for all analytes and was utilized for the analysis of 325 urine specimens. Although no LSD analogs were observed in the samples analyzed, this validated method was demonstrated to be suitable for the analysis of these compounds in laboratories seeking to expand their testing scope. Automated sample preparation allows for the efficient analysis of these analytically challenging compounds with minimal manual handling. Additionally, there was no increased analytical time burden when the LC column and gradient were modified to target nine additional analytes. Detection may improve as new reference standards are developed to allow laboratories to focus on the metabolic products of these analogs. For now, this validated procedure can assist with the routine analysis and surveillance of these emerging substances.

Synthesis and analytical characterization of 1-(2-thienoyl)-6-allyl-nor-d-lysergic acid diethylamide (1T-AL-LAD)

Lysergic acid diethylamide (LSD) analogs have emerged as new psychoactive substances (NPS) since the mid-2010s, and new compounds continue to emerge for recreational use. Since the end of 2023, "1D-AL-LAD" appeared on X (formerly Twitter) and other websites. As for the compound "1D-LSD" (which also has "1D" in the name), several studies show that the ingredient of seized blotter paper printed "1D-LSD" was actually 1-(2-thienoyl)-LSD (1T-LSD). However, there are no reports of seizures of 1-(1,2-dimethylcyclobutanecarbonyl)-LSD (1D-LSD). Accordingly, it was considered that all or at least a certain percentage of "1D-AL-LAD (1-(1,2-dimethylcyclobutanecarbonyl)-6-allyl-nor-LSD)" is actually 1-(2-thienoyl)-6-allyl-nor-LSD (1T-AL-LAD). This compound is handled by a number of distributors as of April 2024; therefore, it should be characterized in advance if seized. In this study, 1T-AL-LAD was synthesized and characterized using nuclear magnetic resonance spectroscopy, Fourier transform-infrared spectroscopy, liquid chromatography/high-resolution mass spectrometry (LC/HRMS) and gas chromatography/MS (GC/MS). This compound was easily distinguished from previously reported lysergamides. There were some differences in the detectability of 1T-AL-LAD compared with other lysergamides using GC/MS and the fragmentation patterns in LC/HRMS. These differences can be reasonably explained. This information will be of help to determine this substance in seized materials should it emerge on the market.

Characterization of the lysergic acid diethylamide analog, 1-(thiophene-2-carbonyl)-N,N-diethyllysergamide (1T-LSD) from a blotter product

Recently, lysergic acid diethylamide (LSD) analogs have appeared worldwide as designer drugs. In this study, we identified a distributed LSD analog from a paper-sheet product. Gas chromatography-mass spectrometry (GC-MS), liquid chromatography-photodiode array-mass spectrometry (LC-PDA-MS), and liquid chromatography with hybrid quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) were used to analyze the sheet product. The sheet product claimed to contain 1-(1,2-dimethylcyclobutanoyl)-N,N-diethyllysergamide (1D-LSD). However, an unknown compound was detected in the product together with tryptamine and L-tryptophan methyl ester. This compound was isolated from the sheets and identified as 1-(thiophene-2-carbonyl)-N,N-diethyl-6-methyl-9,10-didehydroergoline-8β-carboxamide (1-thiophenoyl LSD; 1-(2-thienoyl)-LSD, 1T-LSD), using 1H, 13C nuclear magnetic resonance (NMR) spectroscopy and various two-dimensional NMR techniques. 1T-LSD was shown to have the thiophene-2-carbonyl group at the N1 position instead of the 1,2-dimethylcyclobutane-carbonyl group as claimed. The amount of 1T-LSD (free base) in three individual unit from one sheet was determined to be 87-100 μg per unit using a proton-specific quantitative NMR (1H-qNMR) method. Deacylation of 1T-LSD to LSD was also observed to occur in methanol-d4 during NMR analysis. The UV spectrum of 1T-LSD differed from that of other LSD analogs, and the fluorescence sensitivity was much lower. Because of concerns about the future distribution of products containing new LSD analogs, continued monitoring of newly detected compounds in sheet products is encouraged.

Analytical and behavioral characterization of 1-dodecanoyl-LSD (1DD-LSD)

1-Acetyl-N,N-diethyllysergamide (1A-LSD, ALD-52) was first synthesized in the 1950s and found to produce psychedelic effects similar to those of LSD. Evidence suggests that ALD-52 serves as a prodrug in vivo and hydrolysis to LSD is likely responsible for its activity. Extension of the N1-alkylcarbonyl chain gives rise to novel lysergamides, which spurred further investigations into their structure-activity relationships. At the same time, ALD-52 and numerous homologues have emerged as recreational drugs ("research chemicals") that are available from online vendors. In the present study, 1-dodecanoyl-LSD (1DD-LSD), a novel N1-acylated LSD derivative, was subjected to analytical characterization and was also tested in the mouse head-twitch response (HTR) assay to assess whether it produces LSD-like effects in vivo. When tested in C57BL/6J mice, 1DD-LSD induced the HTR with a median effective dose (ED50) of 2.17 mg/kg, which was equivalent to 3.60 μmol/kg. Under similar experimental conditions, LSD has 27-fold higher potency than 1DD-LSD in the HTR assay. Previous work has shown that other homologues such as ALD-52 and 1-propanoyl-LSD also have considerably higher potency than 1DD-LSD in mice, which suggests that hydrolysis of the 1-dodecanoyl moiety may be comparatively less efficient in vivo. Further investigations are warranted to determine whether the increased lipophilicity of 1DD-LSD causes it to be sequestered in fat, thereby reducing its exposure to enzymatic hydrolysis in plasma and tissues. Further clinical studies are also required to assess its activity in humans and to test the prediction that it could potentially serve as a long-acting prodrug for LSD.

Metabolite markers for three synthetic tryptamines N-ethyl-N-propyltryptamine, 4-hydroxy-N-ethyl-N-propyltryptamine, and 5-methoxy-N-ethyl-N-propyltryptamine

N-Ethyl-N-propyltryptamine (EPT), 4-hydroxy-N-ethyl-N-propyltryptamine (4-OH-EPT), and 5-methoxy-N-ethyl-N-propyltryptamine (5-MeO-EPT) are new psychoactive substances classified as tryptamines, sold online. Many tryptamines metabolize rapidly, and identifying the appropriate metabolites to reveal intake is essential. While the metabolism of 4-OH-EPT and 5-MeO-EPT are not previously described, EPT is known to form metabolites by indole ring hydroxylation among others. Based on general knowledge of metabolic patterns, 5-MeO-EPT is also expected to form ring hydroxylated EPT (5-OH-EPT). In the present study, the aim was to characterize the major metabolites of EPT, 4-OH-EPT, and 5-MeO-EPT, to provide markers for substance identification in forensic casework. The tryptamines were incubated with pooled human liver microsomes at 37°C for up to 4 h. The generated metabolites were separated and detected by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis. The major in vitro EPT metabolites were formed by hydroxylation, N-dealkylation, and carbonylation. In comparison, 4-OH-EPT metabolism was dominated by double bond formation, N-dealkylation, hydroxylation, and carbonylation in vitro and hydroxylation or carbonylation combined with double bond loss, carbonylation, N-dealkylation, and hydroxylation in vivo. 5-MeO-EPT was metabolized by O-demethylation, hydroxylation, and N-dealkylation in vitro. The usefulness of the characterized metabolites in forensic casework was demonstrated by identification of unique metabolites for 4-OH-EPT in a human postmortem blood sample with suspected EPT or 4-OH-EPT intoxication.

Identification of 1-(thiophene-2-carbonyl)-LSD from blotter paper falsely labeled "1D-LSD"

PURPOSE

Since the mid-2010s, lysergic acid diethylamide (LSD) analogs made for substance abuse have periodically emerged. In this case, three pieces of blotter paper labeled "1D-LSD" and presumably impregnated with this LSD analog, were seized. Several websites indicate that 1D-LSD is 1-(1,2-dimethylcyclobutane-1-carbonyl)-LSD. Because this analog is much more difficult to synthesize than previously reported LSD analogs, we doubted that the blotter paper contained 1D-LSD. Herein, we determined the structure of the absorbed compound.

METHODS

One of the seized specimens was extracted and analyzed using gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), high-resolution mass spectrometry (HRMS), and nuclear magnetic resonance (NMR) spectroscopy to estimate the extract components. The estimated compound was then synthesized, yielding an authentic standard. The contents of the seized specimens were identified using authentic standard analysis with GC/MS, LC/MS, and NMR spectroscopy.

RESULTS

Instrumental analyses confirmed the active compound to be 1-(thiophene-2-carbonyl)-LSD, which was inconsistent with the labeling on drug-infused blotter paper.

CONCLUSION

As in this case, similar blotter paper analyses should consider the possibility of a mismatch between the label and ingredient. To the authors' knowledge, this is the first case report in which 1-(thiophene-2-carbonyl)-LSD was seized and the first seizure of an LSD analog in which an aromatic carboxylic acid had been condensed to LSD. This type of lysergamide may become prevalent in the near future, and we should remain alert for newly appearing lysergamides.

Systematic characterization of Lysergic Acid Diethylamide metabolites in Caenorhabditis elegans by ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry

Psychedelic compounds have gained renewed interest for their potential therapeutic applications, but their metabolism and effects on complex biological systems remain poorly understood. Here, we present a systematic characterization of Lysergic Acid Diethylamide (LSD) metabolites in the model organism Caenorhabditis elegans using state-of-the-art analytical techniques. By employing ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry, we putatively identified a range of LSD metabolites, shedding light on their metabolic pathways and offering insights into their pharmacokinetics. Our study demonstrates the suitability of Caenorhabditis elegans as a valuable model system for investigating the metabolism of psychedelic compounds and provides a foundation for further research on the therapeutic potential of LSD.

Identification of LSD analogs, 1cP-AL-LAD, 1cP-MIPLA, 1V-LSD and LSZ in sheet products

PURPOSE

Many analogs of lysergic acid diethylamide (LSD) have recently appeared as designer drugs around the world. These compounds are mainly distributed as sheet products. In this study, we identified three more newly distributed LSD analogs from paper sheet products.

METHODS

The structures of the compounds were determined by gas chromatography-mass spectrometry (GC-MS), liquid chromatography-photodiode array-mass spectrometry (LC-PDA-MS), liquid chromatography with hybrid quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) and nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

From the NMR analysis, the compounds in the four products were identified as 4-(cyclopropanecarbonyl)-N,N-diethyl-7-(prop-2-en-1-yl)-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (1cP-AL-LAD), 4-(cyclopropanecarbonyl)-N-methyl-N-isopropyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo-[4,3-fg]quinoline-9-carboxamide (1cP-MIPLA), N,N-diethyl-7-methyl-4-pentanoyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (1V-LSD) and (2'S,4'S)-lysergic acid 2,4-dimethylazetidide (LSZ). In comparison with the structure of LSD, 1cP-AL-LAD was converted at the positions at N1 and N6, and 1cP-MIPLA was converted at the positions at N1 and N18. The metabolic pathways and biological activities of 1cP-AL-LAD and 1cP-MIPLA have not been reported.

CONCLUSIONS

This is the first report showing that LSD analogs that were converted at multiple positions have been detected in sheet products in Japan. There are concerns about the future distribution of sheet drug products containing new LSD analogs. Therefore, the continuous monitoring for newly detected compounds in sheet products is important.

Analytical profile, in vitro metabolism and behavioral properties of the lysergamide 1P-AL-LAD

Lysergic acid diethylamide (LSD) is known to induce powerful psychoactive effects in humans, which cemented its status as an important tool for clinical research. A range of analogues and derivatives has been investigated over the years, including those classified as new psychoactive substances. This study presents the characterization of the novel lysergamide N,N-diethyl-1-propanoyl-6-(prop-2-en-1-yl)-9,10-didehydroergoline-8β-carboxamide (1P-AL-LAD) using various mass spectrometric, gas- and liquid chromatographic and spectroscopic methods. In vitro metabolism studies using pooled human liver microsomes (pHLM) confirmed that 1P-AL-LAD converted to AL-LAD as the most abundant metabolite consistent with the hypothesis that 1P-AL-LAD may act as a prodrug. Fourteen metabolites were detected in total; metabolic reactions included hydroxylation of the core lysergamide ring structure or the N⁶ -allyl group, formation of dihydrodiol metabolites, N-dealkylation, N¹ -deacylation, dehydrogenation, and combinations thereof. The in vivo behavioral activity of 1P-AL-LAD was evaluated using the mouse head twitch response (HTR), a 5-HT_2A -mediated head movement that serves as a behavioral proxy in rodents for human hallucinogenic effects. 1P-AL-LAD induced a dose-dependent increase in HTR counts with an inverted U-shaped dose-response function, similar to lysergic acid diethylamide (LSD), psilocybin, and other psychedelics. Following intraperitoneal injection, the median effective dose (ED₅₀ ) for 1P-AL-LAD was 491 nmol/kg, making it almost three times less potent than AL-LAD (174.9 nmol/kg). Previous studies have shown that N¹ -substitution disrupts the ability of lysergamides to activate the 5-HT_2A receptor; based on the in vitro metabolism data, 1P-AL-LAD may induce the HTR because it acts as a prodrug and is metabolized to AL-LAD after administration to mice.

Return of the lysergamides. Part VII: Analytical and behavioural characterization of 1-valeroyl-d-lysergic acid diethylamide (1V-LSD)

The psychopharmacological properties of the psychedelic drug lysergic acid diethylamide (LSD) have attracted the interest of several generations of scientists. While further explorations involving novel LSD-type compounds are needed to assess their potential as medicinal drugs, the emergence of novel derivatives as recreational drugs has also been observed. 1-Valeroyl-LSD (also known as 1-valeryl-LSD, 1-pentanoyl-LSD, 1V-LSD, or "Valerie") is a new N¹ -acylated LSD derivative that recently appeared on the online market, and it could be viewed as a higher homolog of ALD-52, 1P-LSD, and 1B-LSD. The present study included the analytical characterization and involved various methods of mass spectrometry (MS), gas and liquid chromatography (GC and LC), nuclear magnetic resonance (NMR) spectroscopy, GC-solid-state infrared (GC-sIR) analysis, and Raman spectroscopy. The in vivo activity of 1V-LSD was assessed using the mouse head-twitch response (HTR), a 5-HT_2A -mediated head movement that serves as a behavioral proxy in rodents for human hallucinogenic effects. Similar to LSD and other psychedelic drugs, the HTR induced by 1V-LSD was dose dependent, and the median effective dose for 1V-LSD was 373 nmol/kg, which was about a third of the potency of LSD (ED₅₀  = 132.8 nmol/kg). Lysergamides containing the N¹ -substituent typically act as weak partial agonists at the 5-HT_2A receptor and are believed to serve as prodrugs for LSD. 1V-LSD is also likely to be hydrolyzed to LSD and serve as a prodrug, but studies to assess the biotransformation and receptor pharmacology of 1V-LSD should be performed to fully elucidate its mechanism of action.

In vitro assays for the functional characterization of (psychedelic) substances at the serotonin receptor 5-HT2A R

Serotonergic psychedelics are substances that induce alterations in mood, perception, and thought, and have the activation of serotonin (5-HT) 2A receptors (5-HT_2A Rs) as a main pharmacological mechanism. Besides their appearance on the (illicit) drug market, e.g. as new psychoactive substances, their potential therapeutic application is increasingly explored. This group of substances demonstrates a broad structural variety, leading to insufficiently described structure-activity relationships, hence illustrating the need for better functional characterization. This review therefore elaborates on the in vitro molecular techniques that have been used the most abundantly for the characterization of (psychedelic) 5-HT_2A R agonists. More specifically, this review covers assays to monitor the canonical G protein signaling pathway (e.g. measuring G protein recruitment/activation, inositol phosphate accumulation, or Ca²⁺ mobilization), assays to monitor non-canonical G protein signaling (such as arachidonic acid release), assays to monitor β-arrestin recruitment or signaling, and assays to monitor receptor conformational changes. In particular, focus lies on the mechanism behind the techniques, and the specific advantages and challenges that are associated with these. Additionally, several variables are discussed that one should consider when attempting to compare functional outcomes from different studies, both linked to the specific assay mechanism and linked to its specific execution, as these may heavily impact the assay outcome.

Overview of the major classes of new psychoactive substances, psychoactive effects, analytical determination and conformational analysis of selected illegal drugs

The misuse of psychoactive substances is attracting a great deal of attention from the general public. An increase use of psychoactive substances is observed among young people who do not have enough awareness of the harmful effects of these substances. Easy access to illicit drugs at low cost and lack of effective means of routine screening for new psychoactive substances (NPS) have contributed to the rapid increase in their use. New research and evidence suggest that drug use can cause a variety of adverse psychological and physiological effects on human health (anxiety, panic, paranoia, psychosis, and seizures). We describe different classes of these NPS drugs with emphasis on the methods used to identify them and the identification of their metabolites in biological specimens. This is the first review that thoroughly gives the literature on both natural and synthetic illegal drugs with old known data and very hot new topics and investigations, which enables the researcher to use it as a starting point in the literature exploration and planning of the own research. For the first time, the conformational analysis was done for selected illegal drugs, giving rise to the search of the biologically active conformations both theoretically and using lab experiments.

Psychedelics in Psychiatry: Neuroplastic, Immunomodulatory, and Neurotransmitter Mechanisms

Mounting evidence suggests safety and efficacy of psychedelic compounds as potential novel therapeutics in psychiatry. Ketamine has been approved by the Food and Drug Administration in a new class of antidepressants, and 3,4-methylenedioxymethamphetamine (MDMA) is undergoing phase III clinical trials for post-traumatic stress disorder. Psilocybin and lysergic acid diethylamide (LSD) are being investigated in several phase II and phase I clinical trials. Hence, the concept of psychedelics as therapeutics may be incorporated into modern society. Here, we discuss the main known neurobiological therapeutic mechanisms of psychedelics, which are thought to be mediated by the effects of these compounds on the serotonergic (via 5-HT_2A and 5-HT_1A receptors) and glutamatergic [via N-methyl-d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors] systems. We focus on 1) neuroplasticity mediated by the modulation of mammalian target of rapamycin-, brain-derived neurotrophic factor-, and early growth response-related pathways; 2) immunomodulation via effects on the hypothalamic-pituitary-adrenal axis, nuclear factor ĸB, and cytokines such as tumor necrosis factor-α and interleukin 1, 6, and 10 production and release; and 3) modulation of serotonergic, dopaminergic, glutamatergic, GABAergic, and norepinephrinergic receptors, transporters, and turnover systems. We discuss arising concerns and ways to assess potential neurobiological changes, dependence, and immunosuppression. Although larger cohorts are required to corroborate preliminary findings, the results obtained so far are promising and represent a critical opportunity for improvement of pharmacotherapies in psychiatry, an area that has seen limited therapeutic advancement in the last 20 years. Studies are underway that are trying to decouple the psychedelic effects from the therapeutic effects of these compounds. SIGNIFICANCE STATEMENT: Psychedelic compounds are emerging as potential novel therapeutics in psychiatry. However, understanding of molecular mechanisms mediating improvement remains limited. This paper reviews the available evidence concerning the effects of psychedelic compounds on pathways that modulate neuroplasticity, immunity, and neurotransmitter systems. This work aims to be a reference for psychiatrists who may soon be faced with the possibility of prescribing psychedelic compounds as medications, helping them assess which compound(s) and regimen could be most useful for decreasing specific psychiatric symptoms.

[Identification of LSD Derivatives, 1cP-LSD, MIPLA and 1B-LSD in Illegal Products as Paper Sheet]

Lysergic acid diethylamide (LSD) is a hallucinogen, synthesized from ergot alkaloid, and controlled as a narcotic in Japan. Recently, LSD derivatives have appeared as designer drugs, all over the world. In previous study, we reported identification and analysis of four LSD derivatives in four paper sheet products. In this study, we detected three additional LSD derivatives from three paper sheet products, which were obtained from September 2019 to March 2020 in Japan. We extracted the compounds from paper sheet products with methanol for LC-MS, high-resolution MS and GC-MS analyses. The compounds were identified as 4-cyclopropionyl-N,N-diethyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (1cP-LSD), N-methyl-N-isopropyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo-[4,3-fg]quinoline-9-carboxamide (MIPLA), 4-butyryl-N,N-diethyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo[4,3-fg]quinoline-9-carboxamide (1B-LSD), by GC-MS, LC-MS, LC-Q-TOF-MS and NMR analyses. As well as other N1-acylated LSD derivatives, 1cP-LSD and 1B-LSD were easily deacylated to LSD during GC-MS analysis, we have to be careful to analyze these compounds.

Serotonin research: Crossing scales and boundaries

Nearly 100 years after the discovery of serotonin, its role remains elusive. Modulation of serotonin transmission is considered in numerous central nervous system (CNS) diseases including depression, anxiety, schizophrenia, obsessive-compulsive disorders, addiction, Parkinson's disease, and Alzheimer's disease. The therapeutic strategies based on serotonin systems have evolved thanks to better identification of the involvement of serotonin in various diseases, the better use of animal models, a better understanding of the molecular environment of serotonin receptors, and ultimately the better understanding of the interaction of serotonin neurotransmission with other biological systems. Some 5-HT receptors are still the object of numerous investigations including 5-HT_1A, 5-HT_2A, and 5-HT₆ receptor subtypes. It is noteworthy that the direction of research is moving towards a simultaneous action at multiple targets either through different 5-HT targets or the consideration of both 5-HT and other targets to achieve better therapeutic responses.

How to Study the Metabolism of New Psychoactive Substances for the Purpose of Toxicological Screenings-A Follow-Up Study Comparing Pooled Human Liver S9, HepaRG Cells, and Zebrafish Larvae

The new psychoactive substances (NPS) market continues to be very dynamic. A large number of compounds belonging to diverse chemical groups continue to emerge. This makes their detection in biological samples challenging for clinical and forensic toxicologists. Knowledge of the metabolic fate of NPS is crucial for developing comprehensive screening procedures. As human studies are not feasible due to ethical concerns, the current study aimed to compare the NPS' metabolic pattern in incubations with pooled human liver S9 fraction (pHLS9), human liver HepaRG cells, and zebrafish larvae. The latter model was recently shown to be a promising preclinical surrogate for human hepatic metabolism of a synthetic cannabinoid. However, studies concerning other NPS classes are still missing and therefore an amphetamine-based N-methoxybenzyl (NBOMe) compound, a synthetic cathinone, a pyrrolidinophenone analog, a lysergamide, as well as another synthetic cannabinoid were included in the current study. Liquid chromatography coupled to Orbitrap-based high-resolution tandem mass spectrometry was used to analyze metabolic data. Zebrafish larvae were found to produce the highest number of phase I but also phase II metabolites (79 metabolites in total), followed by HepaRG cells (66 metabolites). Incubations with pHLS9 produced the least metabolites (57 metabolites). Furthermore, the involvement of monooxygenases and esterases in the metabolic phase I transformations of 4F-MDMB-BINACA was elucidated using single-enzyme incubations. Several cytochrome P450 (CYP) isozymes were shown to contribute, and CYP3A5 was involved in all CYP-catalyzed reactions, while amide and ester hydrolysis were catalyzed by the human carboxylesterase (hCES) isoforms hCES1b and/or hCES1c. Finally, metabolites were compared to those present in human biosamples if data were available. Overall, the metabolic patterns in HepaRG cells provided the worst overlap with that in human biosamples. Zebrafish larvae experiments agreed best with data found in human plasma and urine analysis. The current study underlines the potential of zebrafish larvae as a tool for elucidating the toxicokinetics of NPS in the future.

Pharmacokinetics and subjective effects of 1P-LSD in humans after oral and intravenous administration

1-Propanoyl-lysergic acid diethylamide (1P-LSD) appeared as a non-controlled alternative to LSD a few years ago. Although evidence is beginning to emerge from in vitro and animal studies that 1P-LSD might serve as a prodrug for LSD, an equivalent evaluation in humans is unavailable. Controlled oral and intravenous self-administrations of 100 μg 1P-LSD hemitartrate are reported in two human volunteers followed by analyses of urine and serum samples using a fully validated LC-MS/MS method. Psychometric evaluations included assessment of selected subjective drug effects and administration of the Five-Dimensions of Altered States of Consciousness rating scale (5D-ASC). In serum and urine, oral administrations of 1P-LSD only led to the detection of LSD reflecting biphasic elimination with a terminal elimination half-life of approx. t_1/2 = 6.4 h. 1P-LSD could be detected for only up to 4.16 h in serum and 2.7 h in urine following intravenous administration, whereas LSD was detected in all serum samples (last sampling after approx. 24 h) and up to 80 h in urine. LSD showed first order elimination kinetics with an approx. t_1/2 = 5.7 h, whereas 1P-LSD showed a rapid decrease in concentration within the first hour followed by a slower decrease, most probably due to hydrolysis. The bioavailability of LSD after oral ingestion of 1P-LSD was close to 100%. The psychosensory effects of 1P-LSD and their time course were comparable to those seen after uptake of LSD in other studies which further supports the prodrug hypothesis. The 5D-ASC scores were higher after oral compared with intravenous administration of 1P-LSD.

Return of the lysergamides. Part VI: Analytical and behavioural characterization of 1-cyclopropanoyl-d-lysergic acid diethylamide (1CP-LSD)

Lysergic acid diethylamide (LSD) is a prototypical serotonergic psychedelic drug and the subject of many clinical investigations. In recent years, a range of lysergamides has emerged with the production of some being inspired by the existing scientific literature. Others, for example various 1-acyl substituted lysergamides, did not exist before their appearance as research chemicals. 1-Cylopropanoyl-LSD (1CP-LSD) has recently emerged as a new addition to the group of lysergamide-based designer drugs and is believed to be psychoactive in humans. In this investigation, 1CP-LSD was subjected to detailed analytical characterizations including various mass spectrometry (MS) platforms, gas and liquid chromatography, nuclear magnetic resonance spectroscopy, solid phase and GC condensed phase infrared spectroscopy. Analysis by GC-MS also revealed the detection of artificially induced degradation products. Incubation of 1CP-LSD with human serum led to the formation of LSD, indicating that it may act as a prodrug for LSD in vivo, similar to other 1-acyl substituted lysergamides. The analysis of blotters and pellets is also included. 1CP-LSD also induces the head-twitch response (HTR) in C57BL/6 J mice, indicating that it produces an LSD-like behavioural profile. 1CP-LSD induced the HTR with an ED₅₀ = 430.0 nmol/kg which was comparable to 1P-LSD (ED₅₀ = 349.6 nmol/kg) investigated previously. Clinical studies are required to determine the potency and profile of the effects produced by 1CP-LSD in humans.