Simon D. Brandt

The Designer Methcathinone Analogs, Mephedrone and Methylone, are Substrates for Monoamine Transporters in Brain Tissue

The nonmedical use of ‘designer’ cathinone analogs, such as 4-methylmethcathinone (mephedrone) and 3,4-methylenedioxymethcathinone (methylone), is increasing worldwide, yet little information is available regarding the mechanism of action for these drugs. Here, we employed in vitro and in vivo methods to compare neurobiological effects of mephedrone and methylone with those produced by the structurally related compounds, 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine. In vitro release assays using rat brain synaptosomes revealed that mephedrone and methylone are nonselective substrates for plasma membrane monoamine transporters, similar to MDMA in potency and selectivity. In vivo microdialysis in rat nucleus accumbens showed that i.v. administration of 0.3 and 1.0 mg/kg of mephedrone or methylone produces dose-related increases in extracellular dopamine and serotonin (5-HT), with the magnitude of effect on 5-HT being greater. Both methcathinone analogs were weak motor stimulants when compared with methamphetamine. Repeated administrations of mephedrone or methylone (3.0 and 10.0 mg/kg, s.c., 3 doses) caused hyperthermia but no long-term change in cortical or striatal amines, whereas similar treatment with MDMA (2.5 and 7.5 mg/kg, s.c., 3 doses) evoked robust hyperthermia and persistent depletion of cortical and striatal 5-HT. Our data demonstrate that designer methcathinone analogs are substrates for monoamine transporters, with a profile of transmitter-releasing activity comparable to MDMA. Dopaminergic effects of mephedrone and methylone may contribute to their addictive potential, but this hypothesis awaits confirmation. Given the widespread use of mephedrone and methylone, determining the consequences of repeated drug exposure warrants further study.

Powerful Cocaine-Like Actions of 3,4-Methylenedioxypyrovalerone (MDPV), a Principal Constituent of Psychoactive ‘Bath Salts’ Products

The abuse of psychoactive ‘bath salts’ containing cathinones such as 3,4-methylenedioxypyrovalerone (MDPV) is a growing public health concern, yet little is known about their pharmacology. Here, we evaluated the effects of MDPV and related drugs using molecular, cellular, and whole-animal methods. In vitro transporter assays were performed in rat brain synaptosomes and in cells expressing human transporters, while clearance of endogenous dopamine was measured by fast-scan cyclic voltammetry in mouse striatal slices. Assessments of in vivo neurochemistry, locomotor activity, and cardiovascular parameters were carried out in rats. We found that MDPV blocks uptake of [3H]dopamine (IC50=4.1 nM) and [3H]norepinephrine (IC50=26 nM) with high potency but has weak effects on uptake of [3H]serotonin (IC50=3349 nM). In contrast to other psychoactive cathinones (eg, mephedrone), MDPV is not a transporter substrate. The clearance of endogenous dopamine is inhibited by MDPV and cocaine in a similar manner, but MDPV displays greater potency and efficacy. Consistent with in vitro findings, MDPV (0.1–0.3 mg/kg, intravenous) increases extracellular concentrations of dopamine in the nucleus accumbens. Additionally, MDPV (0.1–3.0 mg/kg, subcutaneous) is at least 10 times more potent than cocaine at producing locomotor activation, tachycardia, and hypertension in rats. Our data show that MDPV is a monoamine transporter blocker with increased potency and selectivity for catecholamines when compared with cocaine. The robust stimulation of dopamine transmission by MDPV predicts serious potential for abuse and may provide a mechanism to explain the adverse effects observed in humans taking high doses of ‘bath salts’ preparations.

Mitigation of post-traumatic stress symptoms by Cannabis resin: a review of the clinical and neurobiological evidence.

It is known from clinical studies that some patients attempt to cope with the symptoms of post-traumatic stress disorder (PTSD) by using recreational drugs. This review presents a case report of a 19-year-old male patient with a spectrum of severe PTSD symptoms, such as intense flashbacks, panic attacks, and self-mutilation, who discovered that some of his major symptoms were dramatically reduced by smoking cannabis resin. The major part of this review is concerned with the clinical and preclinical neurobiological evidence in order to offer a potential explanation of these effects on symptom reduction in PTSD. This review shows that recent studies provided supporting evidence that PTSD patients may be able to cope with their symptoms by using cannabis products. Cannabis may dampen the strength or emotional impact of traumatic memories through synergistic mechanisms that might make it easier for people with PTSD to rest or sleep and to feel less anxious and less involved with flashback memories. The presence of endocannabinoid signalling systems within stress-sensitive nuclei of the hypothalamus, as well as upstream limbic structures (amygdala), point to the significance of this system for the regulation of neuroendocrine and behavioural responses to stress. Evidence is increasingly accumulating that cannabinoids might play a role in fear extinction and antidepressive effects. It is concluded that further studies are warranted in order to evaluate the therapeutic potential of cannabinoids in PTSD.

The confusing case of NRG-1

Since the recent ban on mephedrone,1 2several alternative products have been introduced on internet websites. One of the most prominently discussed second generation products is Energy 1 (NRG-1), also advertised as naphyrone (naphthylpyrovalerone, O-2482), which originated from a group of compounds previously described in the medicinal chemistry …

The first reported fatality associated with the synthetic opioid 3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) and implications for forensic analysis

The search for synthetic opioids as alternatives to opium-based derivatives has provided an important impulse to drug development around the globe. An important goal in the systematic evaluation of new drug candidates is the identification of compounds that provide a more favorable side-effect profile, which includes reduced dependence-producing properties and abuse liability. A rich source of information about these research efforts can be found in the scientific literature. However, the exploration of these important discoveries has also been increasingly mined by largescale producers of these materials, which are then offered for sale. These so-called ‘research chemicals’ or new psychoactive substances (NPS)[1] have created challenges to policy makers, clinicians, and law enforcement around the world.[2] Recent examples of synthetic opioids that emerged as NPS on the market, and which were associated with severe cases of adverse effects, include 3,4-dichloro-N-{[1 (dimethylamino)cyclohexyl]methyl}benzamide (AH-7921), 1-cyclohexyl-4-(1,2- diphenylethyl)piperazines (MT-45) and N-phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]acetamide (acetylfentanyl), respectively (Figure 1). Following the recommendation provided by the World Health Organization’s Expert Committee on Drug Dependence (ECDD),[3] AH-7921 was placed in Schedule I of the 1961 Single Convention, as amended by the 1972 Protocol in 2015.[4] Furthermore, ECDD’s recommendation to place MT-45 into Schedule I and acetylfentanyl in Schedules I and IV of the same Convention[5] have been recently confirmed by the Commission on Narcotic Drugs.[6]3,4-Dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) (Figure1) has recently emerged on the market and can be purchased from various Internet retailers and is a structural isomer of AH-7921 (Figure 1). The preparation of U- 47700 and other derivatives was disclosed by the Upjohn Company in the 1970s[7] followed by the recognition that U-47700 showed increased analgesic properties and morphine-like behavioural features in mice compared to morphine itself.[8,9] The presence of two chiral centres gives rise to a cis- and trans-racemic mixture with the trans-form being advertised for sale. Binding studies also revealed that U-47700 displayed an appreciable selectivity for the μ-opioid receptor over the opioid receptor.[10,11] A variety of cyclohexyl trans-1,2-diamines have been found to be potent analgesics and the vicinal 1,2-diamine pattern has provided access to a large range of substances with diverse biological activities.[12-14] Since U-47700 did not progress to clinical trials, there is no direct clinical information pertaining to its effects. Keeping in mind the various limitations that may be associated with descriptions obtained from self-reporting users, its effects have been described with various positive and negative symptoms but appeared to be essentially comparable to other opioids. Specifically, euphoria was reported in individuals, sometimes being short-lived, as well as general lift in mood with these desired effects being experienced in waves. The negative effects were also opioidbased, including nausea with some users describing respiratory depression. For some users, U-47700 had a shorter duration of action and the urge to keep re-dosing was stated as being very high.[15-16]

AMT (3-(2-aminopropyl)indole) and 5-IT (5-(2-aminopropyl)indole): an analytical challenge and implications for forensic analysis

5-(2-Aminopropyl)indole (5-IT) and 3-(2-aminopropyl)indole (α-methyltryptamine, AMT) are isomeric substances and their differentiation can be a challenge under routine analytical conditions, especially when reference material is unavailable. 5-IT represents a very recent addition to the battery of new psychoactive substances that are commercially available from online retailers. This report illustrates how subtle differences observed under mass spectral and UV conditions can help to facilitate the differentiation between the two isomers. Analyses included (1)  H and (13) C NMR, GC-EI/CI ion trap MS, applications of several U/HPLC-DAD and HPLC-MS methods. Investigations currently underway also highlight the confirmation that AMT was detected in a number of fatal intoxications. These findings also demonstrate that there is a potential risk of misidentification when dealing with both substances.

Salvia divinorum use and phenomenology: results from an online survey

Salvia divinorum is a hallucinogenic plant with ethnopharmacological and recreational uses. It differs from classic serotonergic hallucinogens such as LSD and psilocin in both phenomenology and potent agonist activity of the active component salvinorin A at κ-opioid receptors. Awareness of S. divinorum has grown recently, with both an increase in its public representation and concern over its potential harmful effects. This discussion is particularly relevant as S. divinorum is legal to use in many countries and regions and easily available through online retailers. Drawing upon previous investigations of S. divinorum and other hallucinogens, this study surveyed 154 recent users and questioned them on their use behaviours, consequences of use and other attitudinal measures. Although reporting an extensive substance use history, and considering the limitations of online surveys, there was little evidence of dysfunctional S. divinorum use, and few reports of troubling adverse consequences of use. Furthermore, there was no evidence that users exhibited increased schizotypy. Respondents reported that S. divinorum produced mixed hallucinogenic and dissociative effects, which lends support to assertions that it phenomenologically differs from other hallucinogens with primary serotonergic activity. The functions of use changed with greater experiences with the drug, and although many respondents reported use of S. divinorum as an alternative to illegal drugs it, was apparent that legal proscription would be unlikely to dissuade them from use. These results are discussed with reference to psychopharmacologically informed public health responses to substance use.

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 Ca2+ 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.

Pharmacological Investigations of the Dissociative ‘Legal Highs’ Diphenidine, Methoxphenidine and Analogues

1,2-Diarylethylamines including lanicemine, lefetamine, and remacemide have clinical relevance in a range of therapeutic areas including pain management, epilepsy, neurodegenerative disease and depression. More recently 1,2-diarylethylamines have been sold as ‘legal highs’ in a number of different forms including powders and tablets. These compounds are sold to circumvent governmental legislation regulating psychoactive drugs. Examples include the opioid MT-45 and the dissociative agents diphenidine (DPH) and 2-methoxy-diphenidine (2-MXP). A number of fatal and non-fatal overdoses have been linked to abuse of these compounds. As with many ‘legal highs’, little is known about their pharmacology. To obtain a better understanding, the effects of DPH, 2-MXP and its 3- and 4-MeO- isomers, and 2-Cl-diphenidine (2-Cl-DPH) were investigated using binding studies at 46 central nervous system receptors including the N-methyl-D-aspartate receptor (NMDAR), serotonin, dopamine, norepinephrine, histamine, and sigma receptors as well as the reuptake transporters for serotonin, dopamine and norepinephrine. Reuptake inhibition potencies were measured at serotonin, norepinephrine and dopamine transporters. NMDAR antagonism was established in vitro using NMDAR-induced field excitatory postsynaptic potential (fEPSP) experiments. Finally, DPH and 2-MXP were investigated using tests of pre-pulse inhibition of startle (PPI) in rats to determine whether they reduce sensorimotor gating, an effect observed with known dissociative drugs such as phencyclidine (PCP) and ketamine. The results suggest that these 1,2-diarylethylamines are relatively selective NMDAR antagonists with weak off-target inhibitory effects on dopamine and norepinephrine reuptake. DPH and 2-MXP significantly inhibited PPI. DPH showed greater potency than 2-MXP, acting with a median effective dose (ED50) of 9.5 mg/kg, which is less potent than values reported for other commonly abused dissociative drugs such as PCP and ketamine.

Analytical characterization of three trifluoromethyl‐substituted methcathinone isomers

Cathinone derivatives display a wide range of pharmacological activities and uses; some of them are used as prescription medicines, while others are encountered within a recreational context and are available without a prescription over the Internet and in retail shops around the world. One of the difficulties involved in the unambiguous identification of these new psychoactive substances is the lack of suitable reference standards, particularly when dealing with unreported derivatives and positional isomers. In order to address this need, three trifluoromethyl analogues of the psychostimulant methcathinone, with a CF(3) substituent at the 2-, 3- and 4-position of the phenyl ring (2-TFMAP 1, 3-TFMAP 2 and 4-TFMAP 3), have been prepared for analytical characterization using ATR-FTIR, (1)H and (13) C NMR, and GC-(EI/CI)-ion trap-MS. Differentiation among isomers was feasible by IR, for example when assessing the carbonyl stretch at 1711 (1), 1693 (2) and 1688 (3) cm(-1) , respectively. In addition to the expected iminium base peak at m/z 58, EI-MS displayed key ions at m/z 173, 145, 125, 95, and 75. Separation of isomers was possible under GC conditions. A characteristic feature under CI conditions was the loss of water from the [M + H](+) yielding m/z 214 in addition to m/z 58. Studies currently underway show that the three CF(3) -methcathinone analogues have central nervous system effects and that the 4-CF(3) isomer 3 is more potent as a serotonin uptake inhibitor and releasing agent than the 3-CF(3) and 2-CF(3) counterparts.