Effects of the hallucinogen 2,5-dimethoxy-4-iodophenethylamine (2C-I) and superpotent N-benzyl derivatives on the head twitch response

Analysis of 25 C NBOMe in Seized Blotters by HPTLC and GC-MS

Use of unauthorized synthetic drugs is a serious, forensic, regulatory and public health issue. In this scenario, consumption of drug-impregnated blotters is very frequent. For decades, blotters have been generally impregnated with the potent hallucinogen known as lysergic acid diethylamide (LSD); however, since 2013 blotter stamps with N-2 methoxybenzyl-substituted phenylethylamine hallucinogen designated as "NBOMes" have been seized in Chile. To address this issue with readily accessible laboratory equipment, we have developed and validated a new HPTLC method for the identification and quantitation of 25-C-NBOMe in seized blotters and its confirmation by GC-MS. The proposed method was validated according to SWGTOX recommendations and is suitable for routine analysis of seized blotters containing 25-C-NBOMe. With the validated method, we analyzed 15 real samples, in all cases finding 25-C-NBOMe in a wide dosage range (701.0-1943.5 µg per blotter). In this situation, we can assume that NBOMes are replacing LSD as the main hallucinogenic drug consumed in blotters in Chile.

Return of the lysergamides. Part IV: Analytical and pharmacological characterization of lysergic acid morpholide (LSM-775)

Lysergic acid diethylamide (LSD) is perhaps one of the best-known psychoactive substances and many structural modifications of this prototypical lysergamide have been investigated. Several lysergamides were recently encountered as 'research chemicals' or new psychoactive substances (NPS). Although lysergic acid morpholide (LSM-775) appeared on the NPS market in 2013, there is disagreement in the literature regarding the potency and psychoactive properties of LSM-775 in humans. The present investigation attempts to address the gap of information that exists regarding the analytical profile and pharmacological effects of LSM-775. A powdered sample of LSM-775 was characterized by X-ray crystallography, nuclear magnetic resonance spectroscopy (NMR), gas chromatography mass spectrometry (GC-MS), high mass accuracy electrospray MS/MS, high performance liquid chromatography (HPLC) diode array detection, HPLC quadrupole MS, and GC solid-state infrared analysis. Screening for receptor affinity and functional efficacy revealed that LSM-775 acts as a nonselective agonist at 5-HT1A and 5-HT2A receptors. Head twitch studies were conducted in C57BL/6J mice to determine whether LSM-775 activates 5-HT2A receptors and produces hallucinogen-like effects in vivo. LSM-775 did not induce the head twitch response unless 5-HT1A receptors were blocked by pretreatment with the antagonist WAY-100,635 (1 mg/kg, subcutaneous). These findings suggest that 5-HT1A activation by LSM-775 masks its ability to induce the head twitch response, which is potentially consistent with reports in the literature indicating that LSM-775 is only capable of producing weak LSD-like effects in humans.

Effect of Hallucinogens on Unconditioned Behavior

Because of the ethical and regulatory hurdles associated with human studies, much of what is known about the psychopharmacology of hallucinogens has been derived from animal models. However, developing reliable animal models has proven to be a challenging task due to the complexity and variability of hallucinogen effects in humans. This chapter focuses on three animal models that are frequently used to test the effects of hallucinogens on unconditioned behavior: head twitch response (HTR), prepulse inhibition of startle (PPI), and exploratory behavior. The HTR has demonstrated considerable utility in the neurochemical actions of hallucinogens. However, the latter two models have clearer conceptual bridges to human phenomenology. Consistent with the known mechanism of action of hallucinogens in humans, the behavioral effects of hallucinogens in rodents are mediated primarily by activation of 5-HT2A receptors. There is evidence, however, that other receptors may play secondary roles. The structure-activity relationships (SAR) of hallucinogens are reviewed in relation to each model, with a focus on the HTR in rats and mice.

Human cytochrome P450 kinetic studies on six N-2-methoxybenzyl (NBOMe)-derived new psychoactive substances using the substrate depletion approach

A huge number of new chemical derivatives of known drugs of abuse, so-called new psychoactive substances (NPS), are sold and consumed without prior preclinical and clinical testing. For assessing the elimination behaviors, determination of the kinetic constants K_m and V_max of the cytochrome P450 (CYP) isoforms involved in the hepatic metabolism of NPS could help to predict their contributions to hepatic clearance, drug-drug interactions and polymorphisms. Therefore, the aims of the present study were to determine the K_m and V_max values for CYP isoforms using the substrate depletion approach for the six N-2-methoxybenzyl (NBOMe)-derived NPS 25B-NBOMe, 25C-NBOMe, 25I-NBOMe, 3,4-DMA-NBOMe, 4-EA-NBOMe, and 4-MMA-NBOMe. Furthermore, the contributions of each CYP isozyme to the hepatic net clearance were elucidated using the relative activity factor approach. Several CYPs including CYP1A2, CYP2B6, CYP2C19, CYP2D6, and CYP3A4 were identified to be involved in the metabolism of the investigated compounds. The determined K_m values ranged from 0.010 μM (CYP2D6, 4-MMA-NBOMe) to 13 μM (CYP2B6, 4-EA-NBOMe). All NBOMes were good substrates of CYP2C19 and CYP2D6 resulting in very low K_m values in the nanomolar range. The main contributors to hepatic net clearance were CYP2D6 for 25B-NBOMe (69%), 25C-NBOMe (83%), 25I-NBOMe (61%), 3,4-DMA-NBOMe (89%) as well as for 4-EA-NBOMe (62%) and CYP2C19 for 4-MMA-NBOMe (64%). As more than one isoform was involved in the particular steps, the risk of harm associated with drug-drug interactions might be considered low. However, in cases where substances with high contributions from polymorphically expressed CYP2C19 and CYP2D6 are encountered, inter-individual variations in metabolism and excretion cannot be excluded.

Metabolic Profile Determination of NBOMe Compounds Using Human Liver Microsomes and Comparison with Findings in Authentic Human Blood and Urine

The emergence of novel psychoactive substances (NPS) such as hallucinogenic NBOMes (N-methoxybenzyl derivatives of 2C phenethylamines) in the past few years into the recreational drug market has introduced various challenges in forensic analytical toxicology in regard to adequate and timely detection of these compounds. This is especially true in samples from individuals who have experienced severe and fatal intoxications. The aim of this research was to identify the major Phase I metabolites of selected NBOMe compounds to generate a predicted human metabolic pathway of these substances. An in vitro incubation method of pooled human liver microsomes (HLMs) with four (4) NBOMes was used to identify major metabolites. These metabolic products were identified and confirmed from accurate mass findings of samples analyzed by Ultra Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry. The most common biotransformations observed among this group of NBOMes include O-demethylations at the three methoxy groups, hydroxylations and reduction at the amine group. Other metabolic products observed include positional isomers from various hydroxylation possibilities on the benzene ring and alkyl chains, and secondary metabolism resulting in multiple combinations of the reactions. Many of the major metabolites were subsequently identified in authentic human samples of blood and urine from drug users.

Locomotor and discriminative stimulus effects of four novel hallucinogens in rodents

There has been increasing use of novel synthetic hallucinogenic compounds, 2-(4-bromo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine hydrochloride (25B-NBOMe), 2-(4-chloro-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine hydrochloride (25C-NBOMe), 2-(4-iodo-2,5-dimethoxyphenyl)-N-(2-methoxybenzyl)ethanamine hydrochloride (25I-NBOMe), and N,N-diallyl-5-methoxy tryptamine (5-MeO-DALT), which have been associated with severe toxicities. These four compounds were tested for discriminative stimulus effects similar to a prototypical hallucinogen (-)-2,5-dimethoxy-4-methylamphetamine (DOM) and the entactogen (±)-3,4-methylenedioxymethamphetamine (MDMA). Locomotor activity in mice was tested to obtain dose range and time-course information. 25B-NBOMe, 25C-NBOMe, and 25I-NBOMe decreased locomotor activity. 5-MeO-DALT dose dependently increased locomotor activity, with a peak at 10 mg/kg. A higher dose (25 mg/kg) suppressed activity. 25B-NBOMe fully substituted (≥80%) in both DOM-trained and MDMA-trained rats at 0.5 mg/kg. However, higher doses produced much lower levels of drug-appropriate responding in both DOM-trained and MDMA-trained rats. 25C-NBOMe fully substituted in DOM-trained rats, but produced only 67% drug-appropriate responding in MDMA-trained rats at doses that suppressed responding. 25I-NBOMe produced 74-78% drug-appropriate responding in DOM-trained and MDMA-trained rats at doses that suppressed responding. 5-MeO-DALT fully substituted for DOM, but produced few or no MDMA-like effects. All of the compounds, except 25I-NBOMe, fully substituted for DOM, whereas only 25B-NBOMe fully substituted for MDMA. However, the failure of 25I-NBOMe to fully substitute for either MDMA or DOM was more likely because of its substantial rate-depressant effects than weak discriminative stimulus effects. All of the compounds are likely to attract recreational users for their hallucinogenic properties, but probably of much less interest as substitutes for MDMA. Although no acute adverse effects were observed at the doses tested, the substantial toxicities reported in humans, coupled with the high likelihood for illicit use, suggests that these compounds have the same potential for abuse as other, currently scheduled compounds.

LC-high resolution-MS/MS for identification of 69 metabolites of the new psychoactive substance 1-(4-ethylphenyl-)-N-[(2-methoxyphenyl)methyl] propane-2-amine (4-EA-NBOMe) in rat urine and human liver S9 incubates and comparison of its screening power with further MS techniques

4-EA-NBOMe (N-(2-methoxybenzyl)-4-ethylamphetamine, 1-(4-ethylphenyl-)-N-[(2-methoxyphenyl)methyl]propane-2-amine) is an amphetamine-derived new psychoactive substance (NPS) of the N-methoxybenzyl (NBOMe) group first seized by German custom authorities. In contrast to the phenethylamine NBOMes, studies on the pharmacological, toxicological, or metabolic properties are not yet published. The aims of the presented work were the use of LC-HR-MS/MS for identification of the phase I and II metabolites of 4-EA-NBOMe in rat urine and pooled human S9 fraction (pS9) incubations, to compare metabolite formation in both models, to identify involved monooxygenases, and to elucidate its detectability in standard urine screening approaches (SUSAs) using GC-MS, LC-MSⁿ, and LC-HR-MS/MS. 4-EA-NBOMe was mainly metabolized by oxidation of the ethyl group to phenyl acetaldehyde, to benzoic acid, or to phenylacetic acid, by hydroxylation, and all combined with O-demethylation as well as by glucuronidation and sulfation of the main phase I metabolites in rats. With the exception of the oxidation to benzoic acid, all main metabolic reactions could be confirmed in the incubations with pS9. In total, 36 phase I and 33 phase II metabolites could be identified. Monooxygenase activity screenings revealed the general involvement of cytochrome-P450 (CYP) 1A2, CYP2B6, and CYP3A4. An intake of 4-EA-NBOMe was detectable only via its metabolites by all SUSAs after low-dose administration. The main targets for both LC-MS screenings should be the phenylacetic acid derivative, the mandelic acid derivative both with and without additional O-demethylation, and, for GC-MS, the hydroxy metabolite after conjugate cleavage.

Pharmacology and Toxicology of N-Benzylphenethylamine ("NBOMe") Hallucinogens

Serotonergic hallucinogens induce profound changes in perception and cognition. The characteristic effects of hallucinogens are mediated by 5-HT2A receptor activation. One class of hallucinogens are 2,5-dimethoxy-substituted phenethylamines, such as the so-called 2C-X compounds 2,5-dimethoxy-4-bromophenethylamine (2C-B) and 2,5-dimethoxy-4-iodophenethylamine (2C-I). Addition of an N-benzyl group to phenethylamine hallucinogens produces a marked increase in 5-HT2A-binding affinity and hallucinogenic potency. N-benzylphenethylamines ("NBOMes") such as N-(2-methoxybenzyl)-2,5-dimethoxy-4-iodophenethylamine (25I-NBOMe) show subnanomolar affinity for the 5-HT2A receptor and are reportedly highly potent in humans. Several NBOMEs have been available from online vendors since 2010, resulting in numerous cases of toxicity and multiple fatalities. This chapter reviews the structure-activity relationships, behavioral pharmacology, metabolism, and toxicity of members of the NBOMe hallucinogen class. Based on a review of 51 cases of NBOMe toxicity reported in the literature, it appears that rhabdomyolysis is a relatively common complication of severe NBOMe toxicity, an effect that may be linked to NBOMe-induced seizures, hyperthermia, and vasoconstriction.

NPS: Medical Consequences Associated with Their Intake

Over the last decade, the 'traditional' drug scene has been supplemented - but not replaced - by the emergence of a range of novel psychoactive substances (NPS), which are either newly created or existing drugs, including medications, now being used in novel ways. By the end of 2014, in excess of 500 NPS had been reported by a large number of countries in the world. Most recent data show, however, that synthetic cathinones, synthetic cannabinoids, and psychedelics/phenethylamines account for the largest number of NPS.The present chapter aims at providing an overview of the clinical and pharmacological issues relating to these most popular NPS categories. Given the vast range of medical and psychopathological issues associated with the molecules here described, it is crucial for health professionals to be aware of the effects and toxicity of NPS. A general overview of the acute management of NPS adverse events is provided as well, although further studies are required to identify a range of evidence-based, index molecule-focused, treatment strategies. The rapid pace of change in the NPS online market constitutes a major challenge to the provision of current and reliable scientific knowledge on these substances.

The Toxicology of New Psychoactive Substances: Synthetic Cathinones and Phenylethylamines

BACKGROUND

New psychoactive substances (NPSs) are substitutes for classical drugs of abuse and there are now compounds available from all groups of classical drugs of abuse. During 2014, the number of synthetic cathinones increased dramatically and, together with phenylethylamines, they dominate the NPS markets in the European Union. In total, 31 cathinones and 9 phenylethylamines were encountered in 2014. The aim of this article was to summarize the existing knowledge about the basic pharmacology, metabolism, and human toxicology of relevant synthetic cathinones and phenylethylamines. Compared with existing reviews, we have also compiled the existing case reports from both fatal and nonfatal intoxications.

METHODS

We performed a comprehensive literature search using bibliographic databases PubMed and Web of Science, complemented with Google Scholar. The focus of the literature search was on original articles, case reports, and previously published review articles published in 2014 or earlier.

RESULTS

The rapid increase of NPSs is a growing concern and sets new challenges not only for societies in drug prevention and legislation but also in clinical and forensic toxicology. In vivo and in vitro studies have demonstrated that the pharmacodynamic profile of cathinones is similar to that of other psychomotor stimulants. Metabolism studies show that cathinones and phenylethylamines are extensively metabolized; however, the parent compound is usually detectable in human urine. In vitro studies have shown that many cathinones and phenylethylamines are metabolized by CYP2D6 enzymes. This indicates that these drugs may have many possible drug-drug interactions and that genetic polymorphism may influence their toxicity. However, the clinical and toxicological relevance of CYP2D6 in adverse effects of cathinones and phenylethylamines is questionable, because these compounds are metabolized by other enzymes as well. The toxidromes commonly encountered after ingestion of cathinones and phenylethylamines are mainly of sympathomimetic and hallucinogenic character with a risk of excited delirium and life-threatening cardiovascular effects.

CONCLUSIONS

The acute and chronic toxicity of many NPSs is unknown or very sparsely investigated. There is a need for evidence-based-treatment recommendations for acute intoxications and a demand for new strategies to analyze these compounds in clinical and forensic cases.

Return of the lysergamides. Part I: Analytical and behavioural characterization of 1-propionyl-d-lysergic acid diethylamide (1P-LSD)

1-Propionyl-d-lysergic acid diethylamide hemitartrate (1P-LSD) has become available as a 'research chemical' in the form of blotters and powdered material. This non-controlled derivative of d-lysergic acid diethylamide (LSD) has previously not been described in the published literature despite being closely related to 1-acetyl-LSD (ALD-52), which was developed in the 1950s. This study describes the characterization of 1P-LSD in comparison with LSD using various chromatographic and mass spectrometric methods, infrared and nuclear magnetic resonance spectroscopy. An important feature common to LSD and other serotonergic hallucinogens is that they produce 5-HT2A -receptor activation and induce the head-twitch response (HTR) in rats and mice. In order to assess whether 1P-LSD displays LSD-like properties and activates the 5-HT2A receptor, male C57BL/6 J mice were injected with vehicle (saline) or 1P-LSD (0.025-0.8 mg/kg, IP) and HTR assessed for 30 min using magnetometer coil recordings. It was found that 1P-LSD produced a dose-dependent increase in HTR counts, and that it had ~38% (ED50  = 349.6 nmol/kg) of the potency of LSD (ED50  = 132.8 nmol/kg). Furthermore, HTR was abolished when 1P-LSD administration followed pretreatment with the selective 5-HT2A receptor antagonist M100907 (0.1 mg/kg, SC), which was consistent with the concept that the behavioural response was mediated by activation of the 5-HT2A receptor. These results indicate that 1P-LSD produces LSD-like effects in mice, consistent with its classification as a serotonergic hallucinogen. Nevertheless, the extent to which 1P-LSD might show psychoactive effects in humans similar to LSD remains to be investigated. Copyright © 2015 John Wiley & Sons, Ltd.

Addressing the Complexity of Tourette's Syndrome through the Use of Animal Models

Tourette's syndrome (TS) is a neurodevelopmental disorder characterized by fluctuating motor and vocal tics, usually preceded by sensory premonitions, called premonitory urges. Besides tics, the vast majority—up to 90%—of TS patients suffer from psychiatric comorbidities, mainly attention deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). The etiology of TS remains elusive. Genetics is believed to play an important role, but it is clear that other factors contribute to TS, possibly altering brain functioning and architecture during a sensitive phase of neural development. Clinical brain imaging and genetic studies have contributed to elucidate TS pathophysiology and disease mechanisms; however, TS disease etiology still is poorly understood. Findings from genetic studies led to the development of genetic animal models, but they poorly reflect the pathophysiology of TS. Addressing the role of neurotransmission, brain regions, and brain circuits in TS disease pathomechanisms is another focus area for preclinical TS model development. We are now in an interesting moment in time when numerous innovative animal models are continuously brought to the attention of the public. Due to the diverse and largely unknown etiology of TS, there is no single preclinical model featuring all different aspects of TS symptomatology. TS has been dissected into its key symptomst hat have been investigated separately, in line with the Research Domain Criteria concept. The different rationales used to develop the respective animal models are critically reviewed, to discuss the potential of the contribution of animal models to elucidate TS disease mechanisms.

Psychedelics

Psychedelics (serotonergic hallucinogens) are powerful psychoactive substances that alter perception and mood and affect numerous cognitive processes. They are generally considered physiologically safe and do not lead to dependence or addiction. Their origin predates written history, and they were employed by early cultures in many sociocultural and ritual contexts. After the virtually contemporaneous discovery of (5R,8R)-(+)-lysergic acid-N,N-diethylamide (LSD)-25 and the identification of serotonin in the brain, early research focused intensively on the possibility that LSD and other psychedelics had a serotonergic basis for their action. Today there is a consensus that psychedelics are agonists or partial agonists at brain serotonin 5-hydroxytryptamine 2A receptors, with particular importance on those expressed on apical dendrites of neocortical pyramidal cells in layer V. Several useful rodent models have been developed over the years to help unravel the neurochemical correlates of serotonin 5-hydroxytryptamine 2A receptor activation in the brain, and a variety of imaging techniques have been employed to identify key brain areas that are directly affected by psychedelics. Recent and exciting developments in the field have occurred in clinical research, where several double-blind placebo-controlled phase 2 studies of psilocybin-assisted psychotherapy in patients with cancer-related psychosocial distress have demonstrated unprecedented positive relief of anxiety and depression. Two small pilot studies of psilocybin-assisted psychotherapy also have shown positive benefit in treating both alcohol and nicotine addiction. Recently, blood oxygen level-dependent functional magnetic resonance imaging and magnetoencephalography have been employed for in vivo brain imaging in humans after administration of a psychedelic, and results indicate that intravenously administered psilocybin and LSD produce decreases in oscillatory power in areas of the brain's default mode network.

Effect of 5-HT2A and 5-HT2C receptors on temporal discrimination by mice

Timing deficits are observed in patients with schizophrenia. Serotonergic hallucinogens can also alter the subjective experience of time. Characterizing the mechanism through which the serotonergic system regulates timing will increase our understanding of the linkage between serotonin (5-HT) and schizophrenia, and will provide insight into the mechanism of action of hallucinogens. We investigated whether interval timing in mice is altered by hallucinogens and other 5-HT2 receptor ligands. C57BL/6J mice were trained to perform a discrete-trials temporal discrimination task. In the discrete-trials task, mice were presented with two levers after a variable interval. Responding on lever A was reinforced if the interval was <6.5 s, and responding on lever B was reinforced if the interval was >6.5 s. A 2-parameter logistic function was fitted to the proportional choice for lever B (%B responding), yielding estimates of the indifference point (T50) and the Weber fraction (a measure of timing precision). The 5-HT2A antagonist M100907 increased T50, whereas the 5-HT2C antagonist SB-242,084 reduced T50. The results indicate that 5-HT2A and 5-HT2C receptors have countervailing effects on the speed of the internal pacemaker. The hallucinogen 2,5-dimethoxy-4-iodoamphetamine (DOI; 3 mg/kg IP), a 5-HT2 agonist, flattened the response curve at long stimulus intervals and shifted it to the right, causing both T50 and the Weber fraction to increase. The effect of DOI was antagonized by M100907 (0.03 mg/kg SC) but was unaffected by SB-242,084 (0.1 mg/kg SC). Similar to DOI, the selective 5-HT2A agonist 25CN-NBOH (6 mg/kg SC) reduced %B responding at long stimulus intervals, and increased T50 and the Weber fraction. These results demonstrate that hallucinogens alter temporal perception in mice, effects that are mediated by the 5-HT2A receptor. It appears that 5-HT regulates temporal perception, suggesting that altered serotonergic signaling may contribute to the timing deficits observed in schizophrenia and other psychiatric disorders.

New Drugs of Abuse and Withdrawal Syndromes

New drugs of abuse continue to emerge, including synthetic cannabinoids, synthetic cathinones, and hallucinogens. It is important to recognize their individual psychopharmacologic properties, symptoms of intoxication, and symptoms of withdrawal. Providers must be vigilant of acute medical or psychiatric complications that may arise from use of these substances. Treatment of the patient also includes recognition of any substance use disorders as well as comorbid psychiatric disorders. Although pharmacologic treatments for substance use disorder (of the drugs included in this article) are limited, there are a variety of psychotherapeutic modalities that may be of some benefit.

Next generation of novel psychoactive substances on the horizon - A complex problem to face

BACKGROUND

The last decade has seen a rapid and continuous growth in the availability and use of novel psychoactive substances (NPS) across the world. Although various products are labeled with warnings "not for human consumption", they are intended to mimic psychoactive effects of illicit drugs of abuse. Once some compounds become regulated, new analogues appear in order to satisfy consumers' demands and at the same time to avoid criminalization. This review presents updated information on the second generation of NPS, introduced as replacements of the already banned substances from this class, focusing on their pharmacological properties and metabolism, routes of administration, and effects in humans.

METHODS

Literature search, covering years 2013-2015, was performed using the following keywords alone or in combination: "novel psychoactive substances", "cathinones", "synthetic cannabinoids", "benzofurans", "phenethylamines", "2C-drugs", "NBOMe", "methoxetamine", "opioids", "toxicity", and "metabolism".

RESULTS

More than 400 NPS have been reported in Europe, with 255 detected in 2012-2014. The most popular are synthetic cannabimimetics and psychostimulant cathinones; use of psychedelics and opioids is less common. Accumulating experimental and clinical data indicate that potential harms associated with the use of second generation NPS could be even more serious than those described for the already banned drugs.

CONCLUSIONS

NPS are constantly emerging on the illicit drug market and represent an important health problem. A significant amount of research is needed in order to fully quantify both the short and long term effects of the second generation NPS, and their interaction with other drugs of abuse.

Receptor interaction profiles of novel N-2-methoxybenzyl (NBOMe) derivatives of 2,5-dimethoxy-substituted phenethylamines (2C drugs)

BACKGROUND

N-2-methoxybenzyl-phenethylamines (NBOMe drugs) are newly used psychoactive substances with poorly defined pharmacological properties. The aim of the present study was to characterize the receptor binding profiles of a series of NBOMe drugs compared with their 2,5-dimethoxy-phenethylamine analogs (2C drugs) and lysergic acid diethylamide (LSD) in vitro.

METHODS

We investigated the binding affinities of 2C drugs (2C-B, 2C-C, 2C-D, 2C-E, 2C-H, 2C-I, 2C-N, 2C-P, 2C-T-2, 2C-T-4, 2C-T-7, and mescaline), their NBOMe analogs, and LSD at monoamine receptors and determined functional 5-hydroxytryptamine-2A (5-HT2A) and 5-HT2B receptor activation. Binding at and the inhibition of monoamine uptake transporters were also determined. Human cells that were transfected with the respective human receptors or transporters were used (with the exception of trace amine-associated receptor-1 [TAAR1], in which rat/mouse receptors were used).

RESULTS

All of the compounds potently interacted with serotonergic 5-HT2A, 5-HT2B, 5-HT2C receptors and rat TAAR1 (most Ki and EC50: <1 μM). The N-2-methoxybenzyl substitution of 2C drugs increased the binding affinity at serotonergic 5-HT2A, 5-HT2C, adrenergic α1, dopaminergic D1-3, and histaminergic H1 receptors and monoamine transporters but reduced binding to 5-HT1A receptors and TAAR1. As a result, NBOMe drugs were very potent 5-HT2A receptor agonists (EC50: 0.04-0.5 μM) with high 5-HT2A/5-HT1A selectivity and affinity for adrenergic α1 receptors (Ki: 0.3-0.9 μM) and TAAR1 (Ki: 0.06-2.2 μM), similar to LSD, but not dopaminergic D1-3 receptors (most Ki:>1 μM), unlike LSD.

CONCLUSION

The binding profile of NBOMe drugs predicts strong hallucinogenic effects, similar to LSD, but possibly more stimulant properties because of α1 receptor interactions.

N-Benzyl-5-methoxytryptamines as Potent Serotonin 5-HT2 Receptor Family Agonists and Comparison with a Series of Phenethylamine Analogues

A series of N-benzylated-5-methoxytryptamine analogues was prepared and investigated, with special emphasis on substituents in the meta position of the benzyl group. A parallel series of several N-benzylated analogues of 2,5-dimethoxy-4-iodophenethylamine (2C-I) also was included for comparison of the two major templates (i.e., tryptamine and phenethylamine). A broad affinity screen at serotonin receptors showed that most of the compounds had the highest affinity at the 5-HT2 family receptors. Substitution at the para position of the benzyl group resulted in reduced affinity, whereas substitution in either the ortho or the meta position enhanced affinity. In general, introduction of a large lipophilic group improved affinity, whereas functional activity often followed the opposite trend. Tests of the compounds for functional activity utilized intracellular Ca(2+) mobilization. Function was measured at the human 5-HT2A, 5-HT2B, and 5-HT2C receptors, as well as at the rat 5-HT2A and 5-HT2C receptors. There was no general correlation between affinity and function. Several of the tryptamine congeners were very potent functionally (EC50 values from 7.6 to 63 nM), but most were partial agonists. Tests in the mouse head twitch assay revealed that many of the compounds induced the head twitch and that there was a significant correlation between this behavior and functional potency at the rat 5-HT2A receptor.

NBOMe and 2C substitute phenylethylamine exposures reported to the National Poison Data System

BACKGROUND

Hallucinogenic designer drugs, especially NBOMe and the 2C substitute phenylethylamine series, have been increasing ubiquitous in past years. The purpose of this study is to characterize and compare clinical features of NBOMe and 2C exposures in humans.

METHOD

This is a retrospective cohort study of all single agent exposures to NBOMe and 2C substitute phenylethlamine reported to the National Poison Data System (NPDS) from 1st September 2012 to 30th September 2014.

RESULTS

Over the study period, there were a total 341 cases including 148 NBOMe exposures and 193 2C exposures. The majority cases involved men (73.9%); median age was 18 years (Interquartile-range, 16-21). Similar clinical effects were reported in both groups including tachycardia (45.2%), agitation/irritable (44.3%), hallucination/delusion (32.0%), confusion (19.1%) and hypertension (18.5%). There were higher incidences of hallucination/delusion, single episode seizure and benzodiazepine administration in NBOMe exposures (40.5%, 8.8% and 50.0%respectively) than those of 2C exposures (25.4%, 3.1%, and 32.6% respectively). There were 2.3% death; no difference between two groups.

DISCUSSION

The higher rate of symptoms in NBOMe is consistent with the higher 5HT2A agonistic effects of NBOMe described in both molecular and animal studies.

CONCLUSION

Common clinical effects of NBOMe and 2C exposures were tachycardia, agitation/irritable, hallucination/delusion, confusion, and hypertension. There were higher incidences of hallucination/delusion, single episode seizure and benzodiazepine administration in NBOMe.

Legal highs: staying on top of the flood of novel psychoactive substances

There has been growing clinical, public, and media awareness and concern about the availability and potential harmfulness of so-called 'legal highs', which are more appropriately called new or novel psychoactive substances (NPS). A cat-and-mouse process has emerged wherein unknown chemists and laboratories are producing new, and as yet nonproscribed, compounds for human consumption; and as soon as they are banned, which they inevitably are, slightly modified analogues are produced to circumvent new laws. This rapidly changing environment, 81 new substances were identified in 2013 alone, has led to confusion for clinicians, psychopharmacologists, and the public at large. Our difficulties in keeping up with the process has had a two-fold negative effect: the danger of ignoring what is confusing; and the problem that some of the newer synthesized compounds appear ever more potent. This review aims to circumscribe a quick moving and growing field, and to categorize NPS into five major groups based upon their 'parent' compounds: stimulants similar to cocaine, amphetamines and ecstasy; cannabinoids; benzodiazepine based drugs; dissociatives similar to ketamine and phencyclidine (PCP); and those modelled after classic hallucinogens such as LSD and psilocybin. Pharmacodynamic actions, subjective and physical effects, harmfulness, risk of dependency and, where appropriate, putative clinical potentials are described for each class. Clinicians might encounter NPS in various ways: anecdotal reportage; acute intoxication; as part of a substance misuse profile; and as a precipitant or perpetuating factor for longer-term physical and psychological ill health. Current data are overall limited, and much of our knowledge and treatment strategies are based upon those of the 'parent' compound. There is a critical need for more research in this field, and for professionals to make themselves more aware of this growing issue and how it might affect those we see clinically and try to help: a brave new world of so-called 'psychonauts' consuming NPS will also need informed 'psychotherapeutonauts'. The paper should serve as a primer for clinicians and interested readers, as well as provide a framework into which to place the new substances that will inevitably be synthesized in the future.

Hallucinogen-like effects of 2-([2-(4-cyano-2,5-dimethoxyphenyl) ethylamino]methyl)phenol (25CN-NBOH), a novel N-benzylphenethylamine with 100-fold selectivity for 5-HT₂A receptors, in mice

RATIONALE

2-([2-(4-cyano-2,5-dimethoxyphenyl)ethylamino]methyl)phenol (25CN-NBOH) is structurally similar to N-benzyl substituted phenethylamine hallucinogens currently emerging as drugs of abuse. 25CN-NBOH exhibits dramatic selectivity for 5-HT2A receptors in vitro, but has not been behaviorally characterized.

OBJECTIVE

25CN-NBOH was compared to the traditional phenethylamine hallucinogen R(-)-2,5-dimethoxy-4-iodoamphetamine (DOI) using mouse models of drug-elicited head twitch behavior and drug discrimination.

METHODS

Drug-elicited head twitches were quantified for 10 min following administration of various doses of either DOI or 25CN-NBOH, with and without pretreatments of 0.01 mg/kg 5-HT2A antagonist M100907 or 3.0 mg/kg 5-HT2C antagonist RS102221. The capacity of 25CN-NBOH to attenuate DOI-elicited head twitch was also investigated. Mice were trained to discriminate DOI or M100907 from saline, and 25CN-NBOH was tested for generalization.

RESULTS

25CN-NBOH induced a head twitch response in the mouse that was lower in magnitude than that of DOI, blocked by M100907, but not altered by RS102221. DOI-elicited head twitch was dose-dependently attenuated by 25CN-NBOH pretreatment. 25CN-NBOH produced an intermediate degree of generalization (55 %) for the DOI training dose, and these interoceptive effects were attenuated by M100907. Finally, 25CN-NBOH did not generalize to M100907 at any dose, but ketanserin fully substituted in these animals.

CONCLUSIONS

25CN-NBOH was behaviorally active, but less effective than DOI in two mouse models of hallucinogenic effects. The effectiveness with which M100907 antagonized the behavioral actions of 25CN-NBOH strongly suggests that the 5-HT2A receptor is an important site of agonist action for this compound in vivo.

"My friend said it was good LSD": a suicide attempt following analytically confirmed 25I-NBOMe ingestion

A new class of synthetic hallucinogens called NBOMe has emerged, and reports of adverse effects are beginning to appear. We report on a case of a suicide attempt after LSD ingestion which was analytically determined to be 25I-NBOMe instead. Clinicians need to have a high index of suspicion for possible NBOMe ingestion in patients reporting the recent use of LSD or other hallucinogens.

Recent advances in the neuropsychopharmacology of serotonergic hallucinogens

Serotonergic hallucinogens, such as (+)-lysergic acid diethylamide, psilocybin, and mescaline, are somewhat enigmatic substances. Although these drugs are derived from multiple chemical families, they all produce remarkably similar effects in animals and humans, and they show cross-tolerance. This article reviews the evidence demonstrating the serotonin 5-HT2A receptor is the primary site of hallucinogen action. The 5-HT2A receptor is responsible for mediating the effects of hallucinogens in human subjects, as well as in animal behavioral paradigms such as drug discrimination, head twitch response, prepulse inhibition of startle, exploratory behavior, and interval timing. Many recent clinical trials have yielded important new findings regarding the psychopharmacology of these substances. Furthermore, the use of modern imaging and electrophysiological techniques is beginning to help unravel how hallucinogens work in the brain. Evidence is also emerging that hallucinogens may possess therapeutic efficacy.

Toxicities associated with NBOMe ingestion-a novel class of potent hallucinogens: a review of the literature

BACKGROUND

A new class of synthetic hallucinogens called NBOMe has emerged as drugs of abuse.

OBJECTIVE

Our aim was to conduct a systematic review of published reports of toxicities associated with NBOMe ingestion.

METHODS

We searched PubMed for relevant English-language citations that described adverse effects from analytically confirmed human NBOMe ingestion. Demographic and clinical data were extracted.

RESULTS

A total of 10 citations met the criteria for inclusion, representing 20 individual patients. 25I-NBOMe was the most common analogue identified, followed by 25B-NBOMe and 25C-NBOMe. Fatalities were reported in 3 (15%) cases. Of all the patients, 7 (35%) were discharged after a period of observation, whereas 8 (40.0%) required admission to an intensive care unit. The most common adverse effects were agitation (85.0%), tachycardia (85.0%), and hypertension (65.0%). Seizures were reported in 8 (40.0%) patients. The most common abnormalities reported on laboratory tests were elevated level of creatinine kinase (45.0%), leukocytosis (25.0%), and hyperglycemia (20.0%).

CONCLUSION

NBOMe ingestion is associated with severe adverse effects. Clinicians need to have a high index of suspicion for NBOMe ingestion in patients reporting the recent use of hallucinogens.

The NBOMe hallucinogenic drug series: Patterns of use, characteristics of users and self-reported effects in a large international sample

The NBOMe compounds are a novel series of hallucinogenic drugs that are potent agonists of the 5-HT2A receptor, have a short history of human consumption and are available to buy online, in most countries. In this study, we sought to investigate the patterns of use, characteristics of users and self-reported effects. A cross-sectional anonymous online survey exploring the patterns of drug use was conducted in 2012 (n = 22,289), including questions about the use of 25B-NBOMe, 25C-NBOMe, and 25I-NBOMe and comparison drugs. We found that 2.6% of respondents (n = 582) reported having ever tried one of the three NBOMe drugs and that at 2.0%, 25I-NBOMe was the most popular (n = 442). Almost all (93.5%) respondents whose last new drug tried was a NBOMe drug, tried it in 2012, and 81.2% of this group administered the drug orally or sublingually/buccally. Subjective effects were similar to comparison serotonergic hallucinogens, though higher 'negative effects while high' and greater 'value for money' were reported. The most common (41.7%) drug source was via a website. The NBOMe drugs have emerged recently, are frequently bought using the internet and have similar effects to other hallucinogenic drugs; however, they may pose larger risks, due to the limited knowledge about them, their relatively low price and availability via the internet.

Synthesis and structure-activity relationships of N-benzyl phenethylamines as 5-HT2A/2C agonists

N-Benzyl substitution of 5-HT2A receptor agonists of the phenethylamine structural class of psychedelics (such as 4-bromo-2,5-dimethoxyphenethylamine, often referred to as 2C-B) confer a significant increase in binding affinity as well as functional activity of the receptor. We have prepared a series of 48 compounds with structural variations in both the phenethylamine and N-benzyl part of the molecule to determine the effects on receptor binding affinity and functional activity at 5-HT2A and 5-HT2C receptors. The compounds generally had high affinity for the 5-HT2A receptor with 8b having the highest affinity at 0.29 nM but with several other compounds also exhibiting subnanomolar binding affinities. The functional activity of the compounds was distributed over a wider range with 1b being the most potent at 0.074 nM. Most of the compounds exhibited low to moderate selectivity (1- to 40-fold) for the 5-HT2A receptor in the binding assays, although one compound 6b showed an impressive 100-fold selectivity for the 5-HT2A receptor. In the functional assay, selectivity was generally higher with 1b being more than 400-fold selective for the 5-HT2A receptor.

Molecular pharmacology and ligand docking studies reveal a single amino acid difference between mouse and human serotonin 5-HT2A receptors that impacts behavioral translation of novel 4-phenyl-2-dimethylaminotetralin ligands

During translational studies to develop 4-phenyl-2-dimethylaminotetralin (PAT) compounds for neuropsychiatric disorders, the (2R,4S)-trans-(+)- and (2S,4R)-trans-(-)-enantiomers of the analog 6-hydroxy-7-chloro-PAT (6-OH-7-Cl-PAT) demonstrated unusual pharmacology at serotonin (5-HT) 5-HT2 G protein-coupled receptors (GPCRs). The enantiomers had similar affinities (Ki) at human (h) 5-HT2A receptors (≈ 70 nM). In an in vivo mouse model of 5-HT2A receptor activation [(±)-(2,5)-dimethoxy-4-iodoamphetamine (DOI)-elicited head twitch], however, (-)-6-OH-7-Cl-PAT was about 5-fold more potent than the (+)-enantiomer at attenuating the DOI-elicited response. It was discovered that (+)-6-OH-7-Cl-PAT (only) had ≈ 40-fold-lower affinity at mouse (m) compared with h5-HT2A receptors. Molecular modeling and computational ligand docking studies indicated that the 6-OH moiety of (+)- but not (-)-6-OH-7-Cl-PAT could form a hydrogen bond with serine residue 5.46 of the h5-HT2A receptor. The m5-HT2A as well as m5-HT2B, h5-HT2B, m5-HT2C, and h5-HT2C receptors have alanine at position 5.46, obviating this interaction; (+)-6-OH-7-Cl-PAT also showed ≈ 50-fold lower affinity than (-)-6-OH-7-Cl-PAT at m5-HT2C and h5-HT2C receptors. Mutagenesis studies confirmed that 5-HT2A S5.46 is critical for (+)- but not (-)-6-OH-7-Cl-PAT binding, as well as function. The (+)-6-OH-7-Cl-PAT enantiomer showed partial agonist effects at h5-HT2A wild-type (WT) and m5-HT2A A5.46S point-mutated receptors but did not activate m5-HT2A WT and h5-HT2A S5.46A point-mutated receptors, or h5-HT2B, h5-HT2C, and m5-HT2C receptors; (-)-6-OH-7-Cl-PAT did not activate any of the 5-HT2 receptors. Experiments also included the (2R,4S)-trans-(+)- and (2S,4R)-trans-(-)-enantiomers of 6-methoxy-7-chloro-PAT to validate hydrogen bonding interactions proposed for the corresponding 6-OH analogs. Results indicate that PAT ligand three-dimensional structure impacts target receptor binding and translational outcomes, supporting the hypothesis that GPCR ligand structure governs orthosteric binding pocket molecular determinants and resulting pharmacology.