Allosteric Binding of MDMA to the Human Serotonin Transporter (hSERT) via Ensemble Binding Space Analysis with ΔG Calculations, Induced Fit Docking and Monte Carlo Simulations.

Despite the recent promising results of MDMA (3,4-methylenedioxy-methamphetamine) as a psychotherapeutic agent and its history of misuse, little is known about its molecular mode of action. MDMA enhances monoaminergic neurotransmission in the brain and its valuable psychoactive effects are associated to a dual action on the 5-HT transporter (SERT). This drug inhibits the reuptake of 5-HT (serotonin) and reverses its flow, acting as a substrate for the SERT, which possesses a central binding site (S1) for antidepressants as well as an allosteric (S2) one. Previously, we characterized the spatial binding requirements for MDMA at S1. Here, we propose a structure-based mechanistic model of MDMA occupation and translocation across both binding sites, applying ensemble binding space analyses, electrostatic complementarity, and Monte Carlo energy perturbation theory. Computed results were correlated with experimental data (r = 0.93 and 0.86 for S1 and S2, respectively). Simulations on all hSERT available structures with Gibbs free energy estimations (ΔG) revealed a favourable and pervasive dual binding mode for MDMA at S2, i.e., adopting either a 5-HT or an escitalopram-like orientation. Intermediate ligand conformations were identified within the allosteric site and between the two sites, outlining an internalization pathway for MDMA. Among the strongest and more frequent interactions were salt bridges with Glu494 and Asp328, a H-bond with Thr497, a π-π with Phe556, and a cation-π with Arg104. Similitudes and differences with the allosteric binding of 5-HT and antidepressants suggest that MDMA may have a distinctive chemotype. Thus, our models may provide a framework for future virtual screening studies and pharmaceutical design and to develop hSERT allosteric compounds with a unique psychoactive MDMA-like profile.

Interactions between reinforcement history and drug-primed reinstatement: Studies with MDPV and mixtures of MDPV and caffeine.

Many drugs of abuse are mixed with other psychoactive substances (e.g., caffeine) prior to their sale or use. Synthetic cathinones (e.g., 3,4-methylenedioxypyrovalerone [MDPV]) are commonly mixed with caffeine or other cathinones (e.g., 3,4-methylenedioxy-N-methylcathinone [methylone]), and these "bath salts" mixtures (e.g., MDPV + caffeine) can exhibit supra-additive interactions with regard to their reinforcing and discriminative stimulus properties. However, little is known about relapse-related effects of drug mixtures. In these studies, male Sprague-Dawley rats self-administered 0.032 mg/kg/inf MDPV or a mixture of MDPV + caffeine (0.029 + 0.66 mg/kg/inf, respectively) and then underwent multiple rounds of extinction and reinstatement testing to evaluate the influence of reinforcement history and drug-associated stimuli on the effectiveness of saline (drug-paired stimuli alone), MDPV (0.032-1.0 mg/kg), caffeine (1.0-32 mg/kg), and mixtures of MDPV:caffeine (in 3:1, 1:1, and 1:3 ratios, relative to each drug's ED50 ) to reinstate responding. Dose-addition analyses were used to determine the nature of the drug-drug interaction for each mixture. MDPV and caffeine dose-dependently reinstated responding and were equally effective, regardless of reinforcement history. Most fixed ratio mixtures of MDPV + caffeine exhibited supra-additive interactions, reinstating responding to levels greater than was observed with caffeine and/or MDPV alone. Drug-associated stimuli also played a key role in reinstating responding, especially for caffeine. Together, these results demonstrate that the composition of drug mixtures can impact relapse-related effects of drug mixtures, and "bath salts" mixtures (MDPV + caffeine) may be more effective at promoting relapse-related behaviors than the constituents alone. Further research is needed to determine how other polysubstance reinforcement histories can impact relapse-related behaviors.

Flakka: New Dangerous Synthetic Cathinone on the Drug Scene.

New psychoactive substances are being used as drugs and appear to be quite popular nowadays. Thanks to their specific properties, these drugs create inimitable experiences for intoxicated people. Synthetic cathinones are the most common compounds in these new drugs. Among them, α-pyrrolidopentadione (α-PVP), or "Flakka" (street name), is one of the most famous cathinone-designed drugs. Similar to other synthetic cathinone drugs, α-PVP can effectively inhibit norepinephrine and dopamine transmitters. The adverse reactions of α-PVP mainly include mania, tachycardia, and hallucinations. An increasing number of people are being admitted to emergency wards due to the consequences of their use. This work mainly summarizes the history, synthesis, pharmacology, toxicology, structure-activity relationship, metabolism, clinical process and health risks, poisoning and death, forensic toxicology, and legal status of α-PVP. We hope this review will help bring more attention to the exploration of this substance in order to raise awareness of its negative impacts on humans.

["Legal highs" (new psychoactive substances) : What does the anesthesiologist need to know?] / "Legal Highs" (neue psychoaktive Substanzen) : Was muss der Anästhesist wissen?

In recent years, the social media, the press and the internet have reported more about the topic of "legal highs" and new psychoactive substances (NPS). The use of these drugs is accompanied by a serious risk of undesired side effects, intoxication and even death. The often unknown chemical composition, unspecific clinical presentations and lack of quickly available routine diagnostic tests are aggravating factors in this situation. For anesthesiologists, knowledge of this dangerous substance class plays an important role in the field of preclinical treatment, perioperative management and intensive medical care.

Determination of several synthetic cathinones and an amphetamine-like compound in urine by gas chromatography with mass spectrometry. Method validation and application to real cases.

Most routine practices for drugs-of-abuse testing do not include screening procedures for new psychoactive substances, despite their increasing diffusion, preventing clear knowledge of the real consumption of these drugs in the populations. To make up for this shortcoming, a gas chromatography with mass spectrometry method was developed for the simultaneous determination of 18 synthetic cathinones and one amphetamine-like compound in human urine. The sample preparation was based on liquid-liquid extraction under alkaline condition followed by derivatization with trifluoroacetic anhydride. The separation of the 19 analytes was achieved in less than 10 min. The whole methodology was validated according to national and international guidelines. Selectivity, linearity range, limit of detection and limit of quantitation, precision and accuracy were evaluated. For all the analytes, the calibration curve was linear in the 100-1000 ng/mL concentration range. The limits of detection ranged from 10 to 30 ng/mL and limits of quantitation from 30 to 100 ng/mL. Precisions were in the ranges 0.1-10.4%, and 1.0-12.1% for low (100 ng/mL) and high (1000 ng/mL) concentration, respectively. The accuracy, expressed as bias% was within ±20% for all the analytes. The present method was successfully applied to urine samples originating from autopsies, drug abuse/withdrawal controls, clinical investigations, roadside controls, driving re-licensing, and workplace testing.

Novel complication of Flakka: Stevens-Johnson syndrome/Toxic epidermal necrolysis overlap.

Flakka, as the newest member of the synthetic cathinone group, is a substance with serious cardiovascular, neurological, psychiatric, infectious effects and addictive potential. There are only a few case reports and laboratory studies in the literature and there is no dermatological side effects reported yet. We present the first Stevens-Johnson syndrome/Toxic epidermal necrolysis (SJS/TEN) overlap case after Flakka use.

Impact of common clandestine structural modifications on synthetic cathinone "bath salt" pharmacokinetics.

Since 2009, the synthetic cathinones ("bath salts") have risen in popularity as drugs of abuse. However, there are a paucity of studies that have determined the impact of functional group modifications in the synthetic cathinone chemical structures on plasma and central nervous system (CNS) pharmacokinetics. In the present study, we investigated the in vivo plasma and CNS pharmacokinetics of three synthetic cathinones whose structures differ by lengthening of the α-alkyl chain: methylone (-CH3), butylone (-CH2CH3), and pentylone (-CH2CH2CH3). Male Sprague-Dawley rats were treated with a 20mg/kg subcutaneous dose of the individual synthetic cathinone. Blood samples were obtained at specific times from a jugular vein cannula over an 8hour period. Over a separate three-hour period, CNS samples were obtained using a microdialysis cannula surgically implanted into the lateral ventricle. In the plasma, pentylone, with the longest α-alkyl chain, displayed the highest Cmax and AUC0-∞, and the longest t1/2. Decreasing the α-alkyl chain length as in butylone and methylone significantly decreased the Cmax, AUC0-∞, and t1/2. The plasma pharmacokinetic values are consistent with the greater lipophilicity associated with α-alkyl side chain lengthening. Conversely, in the CNS, methylone and butylone displayed higher Cmax and AUC0-∞ values than pentylone. These contrary findings in the CNS and plasma demonstrate that lengthening of the α-alkyl chain of methylone, butylone, and pentylone yields differential pharmacokinetic properties in the CNS as compared to the plasma.

Escalation of intravenous self-administration of methylone and mephedrone under extended access conditions.

The recreational use of substituted cathinones continues to grow as a public health concern in the United States. Studies have shown that extended access to intravenous (i.v.) self-administration of stimulants, such as cocaine and methamphetamine, results in escalation of drug intake relative to shorter access; however, little is known about the impact of extended access on self-administration of entactogen class stimulants such as methylone and 4-methylmethcathinone (mephedrone). Male Wistar rats were randomly assigned to short-access (ShA, 2- h) and long-access (LgA, 6- h) groups and trained to self-administer methylone or mephedrone (0.5 mg/kg/infusion) using a fixed-ratio 1 response contingency. The methylone-trained groups were evaluated on a progressive-ratio (PR) procedure incorporating dose-substitution of methylone (0.125-2.5 mg/kg/infusion), mephedrone (0.125-2.5 mg/kg/infusion) or methamphetamine (MA; 0.01-0.5 mg/kg/infusion). Mephedrone-trained rats were similarly evaluated on a PR with mephedrone and MA. Rats trained with LgA to methylone and mephedrone earned more infusions during acquisition compared with ShA groups. Mephedrone-trained LgA rats reached significantly higher breakpoints than all other groups in mephedrone and MA PR tests. Methylone-trained LgA rats exhibited a rightward shift of the peak effective dose but no overall efficacy change compared with methylone-trained ShA rats. These findings show that the self-administration of mephedrone escalates under LgA conditions in a manner similar to traditional stimulants whereas escalation of 6 h intakes of methylone is not accompanied by differences in PR performance. Thus mephedrone represents the greater risk for dysregulated drug consumption.

A case of fatal idiosyncratic reaction to the designer drug 3,4-methylenedioxypyrovalerone (MDPV) and review of the literature.

The stimulant designer drug 3,4-methylenedioxypyrovalerone (MDPV) was first synthesized by Boehringer Ingelheim in 1969 and introduced on the black market in 2006. Only a small number of fatal intoxication cases have been reported in the literature, all with significant blood MDPV concentrations. In this report, we describe one fatality attributed to an idiosyncratic reaction to MDPV. The victim displayed agitation, violent behavior and delirium followed by cardiac arrest. Hyperthermia was observed at the hospital. The MDPV cardiac and femoral blood concentrations were 6 ng/mL. The presence of excited delirium syndrome and MDPV, a drug with a pharmacology similar to cocaine, leads to the conclusion that the victim suffered a fatal adverse reaction to MDPV. This is the first published case of idiosyncratic reaction to MDPV.

Linear pharmacokinetics of 3,4-methylenedioxypyrovalerone (MDPV) and its metabolites in the rat: relationship to pharmacodynamic effects.

3,4-Methylenedioxypyrovalerone (MDPV) is a commonly abused synthetic cathinone in the United States and is associated with dangerous side effects. MDPV is a dopamine transporter blocker that is 10-fold more potent than cocaine as a locomotor stimulant in rats. Previous in vitro and in vivo metabolism studies identified 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) as the two primary MDPV metabolites. This study examined MDPV pharmacokinetics and metabolism, along with associated pharmacodynamic effects in rats receiving 0.5, 1.0 and 2.0 mg/kg subcutaneous (s.c.) MDPV. Blood was collected by an indwelling jugular catheter before dosing and at 10, 20, 30, 60, 120, 240 and 480 minutes thereafter. Plasma specimens were analyzed by liquid chromatography coupled to high-resolution tandem mass spectrometry. Maximum concentrations (Cmax ) and area-under-the-curve (AUC) for MDPV and two metabolites increased proportionally with administered dose, showing linear pharmacokinetics. MDPV exhibited the highest Cmax at all doses (74.2-271.3 µg/l) and 4-OH-3-MeOH-PV the highest AUC (11 366-47 724 minutes per µg/l), being the predominant metabolite. MDPV time to Cmax (Tmax ) was 12.9-18.6 minutes, while 3,4-catechol-PV and 4-OH-3-MeO-PV peaked later with Tmax 188.6-240 minutes after s.c. dosing. Horizontal locomotor activity (HLA) and stereotypy correlated positively with plasma MDPV concentrations, while HLA correlated negatively with MDPV metabolites. These results suggest that the parent compound mediates motor stimulation after systemic MDPV administration, but additionally, metabolites may be inhibitory, may not be active or may not pass the blood brain barrier.

Devastating Delayed Leukoencephalopathy Associated with Bath Salt Inhalation.

BACKGROUND: "Bath salts" or synthetic cathinone toxicity remains a potentially deadly clinical condition. We report a delayed leukoencephalopathy with persistent minimally conscious state. METHODS: Case report. RESULTS: A 36-year-old man presents with delayed encephalopathy, dysautonomia, fulminant hepatic failure, and renal failure from severe rhabdomyolysis after consuming bath salts. MRI showed diffusion restriction in the splenium of the corpus callosum and subcortical white matter. CONCLUSIONS: The combination of acute leukoencephalopathy, rhabdomyolysis and fulminant hepatic failure may point to bath salt inhalation and should be known to neurointensivists.

Chiral resolution and absolute configuration of the enantiomers of the psychoactive "designer drug" 3,4-methylenedioxypyrovalerone.

Illicit rac-MDPV (3,4-methylenedioxypyrovalerone), manufactured in clandestine labs, has become widely abused for its cocaine-like stimulant properties. It has recently been found as one of the toxic materials in the so-called "bath salts," producing, among other effects, psychosis and tachycardia in humans when introduced by any of the several routes of administration (e.g., intravenous, oral, etc.). The considerable toxicity of this "designer drug" probably resides in one of the enantiomers of the racemate. In order to obtain a sufficient amount of the enantiomers of rac-MDPV to determine their activity, we improved the known synthesis of rac-MDPV and found chemical resolving agents, (+)- and (-)-2'-bromotetranilic acid, that gave the MDPV enantiomers in >96% enantiomeric excess as determined by (1) H nuclear magnetic resonance and chiral high-performance liquid chromatography. The absolute stereochemistry of these enantiomers was determined by single-crystal X-ray diffraction studies.

Cathinone neurotoxicity ("The "3Ms").

Synthetic cathinones are designer drugs of the phenethylamine class, structurally and pharmacologically similar to amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), cathinone and other related substances. New analogues, legal at least, until formally banned (a time consuming process), are introduced almost daily The United Nations estimates nearly 250 new drug analogues are produced per year. Various combinations of these drugs are sold under the name of "bath salts". They can be ingested by any route and some appear capable of causing great harm, mostly behavioral. One drug in particular, MDVP, appears to frequently cause symptoms indistinguishable from the classic findings in Excited Delirium Syndrome (ExDS). Little is known about the pathology or clinical toxicology of these drugs but their molecular mechanism of action seems to be identical with that of cocaine. This mini-review examines what little is known on the subject and explains the suspected mechanisms of excited delirium syndrome.

The New Designer Drug Wave: A Clinical, Toxicological, and Legal Analysis.

This article reviews clinical, toxicological, and legal issues related to designer drug abuse, with a focus on synthetic cathinones (bath salts). Synthetic cathinones are amphetamine-type central nervous system (CNS) stimulants that produce similar effects to amphetamine. Like amphetamine, synthetic cathinones can also result in neurological and cardiovascular side-effects consistent with sympathomimetic toxicity. The differential for a patient presenting with the signs and symptoms of synthetic cathinone toxicity is broad, and laboratory testing for synthetic cathinones is of limited value in acute management. If a diagnosis of cathinone-induced delirium is suspected, treatment efforts should focus on controlling agitation and then treating medical complications such as metabolic acidosis. Physicians should be aware of these new drugs, not only to optimally treat patients, but also to raise awareness of the dangers of designer drug use through patient counseling and community outreach programs.

[New psychoactive substances and their prevalence in the Czech Republic]. / Nové psychoaktivní látky a jejich výskyt v Ceské republice.

Recently, there is a global growing concern over the new (mainly synthetic) psychoactive substances, known as legal highs, research chemicals or bath salts. They are represented by various chemical groups imitating "old" illicit drugs with stimulant, euphoric, hallucinogenic or sedative effects. In the Czech Republic, the peak of their use and supply was observed at the beginning of 2011, when new psychoactive substances were available in smart shops known locally as Amsterdam shops - in that time mainly synthetic cathinones and also synthetic cannabinoids were present. After legislative change that placed tens of new substances under the control of criminal law in April 2011, new psychoactive substances are available at Internet and their use is (after short and media driven boom in early 2011) rather limited and decreasing. Though, the use of new synthetic stimulants was recently reported locally among problem (injecting) drug users; new very potent synthetic opioids represent potential threat of further expansion in this users subgroup.

Effects of α-pyrrolidinopentiophenone and 4-methyl-N-ethylcathinone, two synthetic cathinones commonly found in second-generation "bath salts," on intracranial self-stimulation thresholds in rats.

BACKGROUND: Use of synthetic cathinones, which are designer stimulants found in "bath salts," has increased dramatically in recent years. Following governmental bans of methylenedioxypyrovalerone, mephedrone, and methylone, a second generation of synthetic cathinones with unknown abuse liability has emerged as replacements. METHODS: Using a discrete trials current intensity threshold intracranial self-stimulation procedure, the present study assessed the effects of 2 common second-generation synthetic cathinones, α-pyrrolidinopentiophenone (0.1-5 mg/kg) and 4-methyl-N-ethcathinone (1-100 mg/kg) on brain reward function. Methamphetamine (0.1-3 mg/kg) was also tested for comparison purposes. RESULTS: Results revealed both α-pyrrolidinopentiophenone and 4-methyl-N-ethcathinone produced significant intracranial self-stimulation threshold reductions similar to that of methamphetamine. α-Pyrrolidinopentiophenone (1 mg/kg) produced a significant maximal reduction in intracranial self-stimulation thresholds (~19%) most similar to maximal reductions produced by methamphetamine (1 mg/kg, ~20%). Maximal reductions in intracranial self-stimulation thresholds produced by 4-methyl-N-ethcathinone were observed at 30 mg/kg (~15%) and were comparable with those observed with methamphetamine and α-pyrrolidinopentiophenone tested at the 0.3-mg/kg dose (~14%). Additional analysis of the ED50 values from log-transformed data revealed the rank order potency of these drugs as methamphetamine ≈ α-pyrrolidinopentiophenone>4-methyl-N-ethcathinone. CONCLUSIONS: These data suggest that the newer second-generation synthetic cathinones activate the brain reward circuitry and thus may possess a similar degree of abuse potential as prototypical illicit psychostimulants such as methamphetamine as well as the first generation synthetic cathinone methylenedioxypyrovalerone, as previously reported.

Age-dependent MDPV-induced taste aversions and thermoregulation in adolescent and adult rats.

Adolescent rats are more sensitive to the rewarding and less sensitive to the aversive properties of various drugs of abuse than their adult counterparts. Given a nationwide increase in use of "bath salts," the present experiment employed the conditioned taste aversion procedure to assess the aversive effects of 3,4-methylenedioxypyrovalerone (MDPV; 0, 1.0, 1.8, or 3.2 mg/kg), a common constituent in "bath salts," in adult and adolescent rats. As similar drugs induce thermoregulatory changes in rats, temperature was recorded following MDPV administration to assess if thermoregulatory changes were related to taste aversion conditioning. Both age groups acquired taste aversions, although these aversions were weaker and developed at a slower rate in the adolescent subjects. Adolescents increased and adults decreased body temperature following MDPV administration with no correlation to aversions. The relative insensitivity of adolescents to the aversive effects of MDPV suggests that MDPV may confer an increased risk in this population.

Synthetic cathinones ("bath salts").

BACKGROUND: Synthetic cathinones are popularly referred to in the media as "bath salts." Through the direct and indirect activation of the sympathetic nervous system, smoking, snorting, or injecting synthetic cathinones can result in tachycardia, hypertension, hyperthermia, myocardial infarction, and death. OBJECTIVE: The chemical structures and names of bath salts identified by the Ohio Attorney General's Bureau of Criminal Investigation are presented. Based on their common pharmacophores, we review the history, pharmacology, toxicology, detection methods, and clinical implications of synthetic cathinones. Through the integration of this information, the pharmacological basis for the management of patients using synthetic cathinones is presented. DISCUSSION: Synthetic cathinones activate central serotonergic and dopaminergic systems contributing to acute psychosis and the peripheral activation of the sympathetic nervous system. The overstimulation of the sympathetic nervous system contributes to the many toxicities reported with bath salt use. The pharmacological basis for managing these patients is targeted at attenuating the activation of these systems. CONCLUSIONS: Treatment of patients presenting after using bath salts should be focused on reducing agitation and psychosis and supporting renal perfusion. The majority of successfully treated synthetic cathinones cases have used benzodiazepines and antipsychotics along with general supportive care.

Investigation of "bath salts" use patterns within an online sample of users in the United States.

"Bath salts" are synthetic stimulant "legal highs" that have recently been banned in the US. Epidemiological data regarding bath salts use are limited. In the present study, 113 individuals in the US reporting use of bath salts completed an anonymous, online survey characterizing demographic, experiential, and psychological variables. Respondents were more often male, 18-24 years old, and Caucasian/White with some college education. Past-year use was typically low (≤ 10 days), but marked by repeated dosing. Intranasal was the most frequently reported administration route and subjective effects were similar to other stimulants (e.g., cocaine, amphetamines). Bath salts use was associated with increased sexual desire and sexual HIV risk behavior, and met DSM-5 diagnostic criteria for disordered use in more than half of respondents. Bath salts use persists in the US despite federal bans of cathinone-like constituents. Self-reported stimulant-like effects of bath salts suggest their use as substitutes for traditional illicit stimulants. Data revealed more normative outcomes vis-à-vis extreme accounts by media and medical case reports. However, indications of product abuse potential and sexual risk remain, suggesting bath salts pose potential public health harm.

Not-so-clean fun: a profile of bath salt users among a college sample in the United States.

This research examines the characteristics of users of synthetic stimulants marketed as "bath salts." Synthetic stimulants such as MDPV (3,4-Methylenedioxypyrovalerone), Mephedrone (4-Methylmethcathinone), and Methylone (3,4-Methylenedioxymethcathinone) are often contained in products sold at convenience stores and over the Internet in the United States. Despite the recent legal action banning these types of synthetic stimulants, little is known about the characteristics of the users of these substances. This research provides a profile of bath salt users in the United States among an emerging adult population. A self-report survey instrument was administered to 2,349 students at a large university in the southeastern United States. Respondents indicated whether they had used synthetic stimulants and reported demographic characteristics. Results indicated that users of bath salts were more likely to be male, Hispanic or Native American, student athletes, employed, identify as a members of the LGBT community, and users of other substances.