Pharmacology of MDMA- and Amphetamine-Like New Psychoactive Substances

New psychoactive substances (NPS) with amphetamine-, aminoindan-, and benzofuran basic chemical structures have recently emerged for recreational drug use. Detailed information about their psychotropic effects and health risks is often limited. At the same time, it emerged that the pharmacological profiles of these NPS resemble those of amphetamine or 3,4-methylenedioxymethamphetamine (MDMA). Amphetamine-like NPS induce psychostimulation and euphoria mediated predominantly by norepinephrine (NE) and dopamine (DA) transporter (NET and DAT) inhibition and transporter-mediated release of NE and DA, thus showing a more catecholamine-selective profile. MDMA-like NPS frequently induce well-being, empathy, and prosocial effects and have only moderate psychostimulant properties. These MDMA-like substances primarily act by inhibiting the serotonin (5-HT) transporter (SERT) and NET, also inducing 5-HT and NE release. Monoamine receptor interactions vary considerably among amphetamine- and MDMA-like NPS. Clinically, amphetamine- and MDMA-like NPS can induce sympathomimetic toxicity. The aim of this chapter is to review the state of knowledge regarding these substances with a focus on the description of the in vitro pharmacology of selected amphetamine- and MDMA-like NPS. In addition, it is aimed to provide links between pharmacological profiles and in vivo effects and toxicity, which leads to the conclusion that abuse liability for amphetamine-like NPS may be higher than for MDMA-like NPS, but that the risk for developing the life-threatening serotonin syndrome may be increased for MDMA-like NPS

Changes in neuronal activity in rat primary cortical cultures induced by illicit drugs and new psychoactive substances (NPS) following prolonged exposure and washout to mimic human exposure scenarios

The use of new psychoactive substances (NPS) is increasing despite associated health risks and limited pharmacological and toxicological knowledge. Information is available mainly for acute effects on specific targets like monoamine transporters and receptors. Recently, we have shown the ability of several NPS and illicit drugs to modulate neuronal activity during acute exposure. While these acute measurements provide valuable information regarding the potency and possible structure-activity relationships, an exposure scenario more representative of human exposure would increase insight and aid translation to the human situation. Therefore, we investigated the effects on neuronal activity after acute (30 min) and prolonged (5 h) exposure to amphetamine-type stimulants, cathinones, hallucinogens, piperazines and cocaine using rat primary cortical cultures grown on multi-well microelectrode arrays. To investigate the reversibility of effects, activity was also measured after a washout period of 19 h. During acute exposure, all compounds concentration-dependently decreased neuronal activity. Compared to acute exposure, prolonged exposure did not further decrease neuronal activity. Following washout, effects of 3 out of 11 drugs (methamphetamine, cocaine, and benzylpiperazine) were fully reversible, whereas effects induced by MDMA, PMMA and α-PVP were partially reversible. Neuronal activity did not recover after 19 h washout following exposure to the highest concentration of MDPV, 2C-B, 25B-NBOMe, and TFMPP. On the contrary, exposure to low concentrations of methylone, and to some extent of 2C-B, increased neuronal activity after the washout period. Hazard characterization of emerging NPS should include at least an acute exposure to determine a potency rank order. Supplementing the (acute and prolonged) exposure scenario with a washout period allows investigation of the reversibility of effects. The possibility of a neuronal network to regain activity after drug exposure appears independent of drug class or IC50 values for acute and prolonged exposure. Even though neuronal activity (partly) recovers after washout following exposure to most drugs, it is perturbing that complete recovery of neuronal activity is observed only for a minority of the tested drugs

Changes in neuronal activity in rat primary cortical cultures induced by illicit drugs and new psychoactive substances (NPS) following prolonged exposure and washout to mimic human exposure scenarios

The use of new psychoactive substances (NPS) is increasing despite associated health risks and limited pharmacological and toxicological knowledge. Information is available mainly for acute effects on specific targets like monoamine transporters and receptors. Recently, we have shown the ability of several NPS and illicit drugs to modulate neuronal activity during acute exposure. While these acute measurements provide valuable information regarding the potency and possible structure-activity relationships, an exposure scenario more representative of human exposure would increase insight and aid translation to the human situation. Therefore, we investigated the effects on neuronal activity after acute (30 min) and prolonged (5 h) exposure to amphetamine-type stimulants, cathinones, hallucinogens, piperazines and cocaine using rat primary cortical cultures grown on multi-well microelectrode arrays. To investigate the reversibility of effects, activity was also measured after a washout period of 19 h. During acute exposure, all compounds concentration-dependently decreased neuronal activity. Compared to acute exposure, prolonged exposure did not further decrease neuronal activity. Following washout, effects of 3 out of 11 drugs (methamphetamine, cocaine, and benzylpiperazine) were fully reversible, whereas effects induced by MDMA, PMMA and α-PVP were partially reversible. Neuronal activity did not recover after 19 h washout following exposure to the highest concentration of MDPV, 2C-B, 25B-NBOMe, and TFMPP. On the contrary, exposure to low concentrations of methylone, and to some extent of 2C-B, increased neuronal activity after the washout period. Hazard characterization of emerging NPS should include at least an acute exposure to determine a potency rank order. Supplementing the (acute and prolonged) exposure scenario with a washout period allows investigation of the reversibility of effects. The possibility of a neuronal network to regain activity after drug exposure appears independent of drug class or IC50 values for acute and prolonged exposure. Even though neuronal activity (partly) recovers after washout following exposure to most drugs, it is perturbing that complete recovery of neuronal activity is observed only for a minority of the tested drugs

Hyperthermia exacerbates the acute effects of psychoactive substances on neuronal activity measured using microelectrode arrays (MEAs) in rat primary cortical cultures in vitro

Hyperthermia is a well-known, potentially life-threatening, side effect of stimulant psychoactive substances that worsens the neurological outcome of hospitalized patients. However, current in vitro methods to assess the hazard of psychoactive substances do not account for hyperthermia. Therefore, this study determined the potency of five psychoactive substances (cocaine, MDMA (3,4-methylenedioxymethamphetamine), methamphetamine, 3-MMC (3-methylmethcathinone) and TFMPP (3-trifluoromethylphenylpiperazine)) to affect neuronal activity at physiological and hyperthermic conditions. Neuronal activity of rat cortical cultures grown on microelectrode arrays (MEAs) was recorded at 37 °C before, and after 30 min and 4.5 h drug exposure (1-1000 μM) at 37 °C or 41 °C. Neuronal activity was also measured after a washout period of 19 h (24 h after the start of the exposure) at 37 °C to investigate recovery of neuronal activity. Without drug exposure, hyperthermia induced a modest decrease in neuronal activity. Following acute (30 min) exposure at 37 °C, all drugs concentration-dependently inhibited neuronal activity. Increasing the temperature to 41 °C significantly exacerbated the reduction of neuronal activity ~ 2-fold for all drugs compared to 37 °C. Prolonged (4.5 h) exposure at 41 °C decreased neuronal activity comparable to 37 °C. Neuronal activity (partly) recovered following drug exposure at both temperatures, although recovery from exposure at 41 °C was less pronounced for most drugs. None of the exposure conditions affected viability. Since acute exposure at hyperthermic conditions exacerbates the decrease in neuronal activity induced by psychoactive substances, effects of hyperthermia should be included in future hazard assessment of illicit drugs and new psychoactive substances (NPS)

Monitoring new psychoactive substances (NPS) in The Netherlands : data from the drug market and the Poisons Information Centre

BACKGROUND: In recent years, the number of new psychoactive substances (NPS) appearing on the illicit drug market strongly increased. However, little is known about their toxic effects and risks. Therefore, we determined the most frequently occurring NPS in The Netherlands and combined this with data regarding drug-related intoxications. METHODS: Data from the Drugs Information and Monitoring System (DIMS) and the Dutch Poisons Information Centre (DPIC) were combined and jointly analyzed. RESULTS: The number of drug samples submitted to DIMS for analysis containing NPS increased from 22 in 2007 to 431 samples in 2013. The most frequently submitted NPS in 2013 included 4-bromo-2,5-dimethoxyphenethylamine (2C-B), 4-fluoroamphetamine (4-FA), methoxetamine (MXE) and 6-(2-aminopropyl)benzofuran (6-APB). From 2012 onwards, the number of NPS bought as drug of choice exceeded those appearing as adulterants in established drugs. The DPIC was consulted about 35 NPS exposures in 2013, most frequently involving 4-FA, mephedrone, MXE, 2C-B and 6-APB. Following NPS exposure, neurological and psychological symptoms were most frequently reported, like agitation and hallucinations. In addition, cardiovascular symptoms like hypertension and tachycardia often occurred. CONCLUSIONS: NPS are currently being purchased as drug of choice in The Netherlands and their availability and use is increasing. Although pharmacological and toxicological data are scarce, NPS can induce pronounced clinical effects. Therefore, the monitoring of trends in NPS prevalence needs to be continued, combined with reported clinical effects, and preferably supported by analytical confirmation of exposures in such patients

Methamphetamine, amphetamine, MDMA ('ecstasy'), MDA and mCPP modulate electrical and cholinergic input in PC12 cells

Reversal of the dopamine (DA) membrane transporter is the main mechanism through which many drugs of abuse increase DA levels. However, drug-induced modulation of exocytotic DA release by electrical (depolarization) and neurochemical inputs (e.g., acetylcholine (ACh)) may also contribute. We therefore investigated effects of methamphetamine, amphetamine, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and meta-chlorophenylpiperazine (mCPP) (1-1000 μM) on these inputs by measuring drug-induced changes in basal, depolarization- and ACh-evoked intracellular calcium concentrations ([Ca(2+)](i)) using a dopaminergic model (PC12 cells) and Fura 2 calcium imaging. The strongest drug-induced effects were observed on cholinergic input. At 0.1mM all drugs inhibited the ACh-evoked [Ca(2+)](i) increases by 40-75%, whereas ACh-evoked [Ca(2+)](i) increases were nearly abolished following higher drug exposure (1mM, 80-97% inhibition). Additionally, high MDMA and mCPP concentrations increased basal [Ca(2+)](i), but only following prior stimulation with ACh. Interestingly, low concentrations of methamphetamine or amphetamine (10 μM) potentiated ACh-evoked [Ca(2+)](i) increases. Depolarization-evoked [Ca(2+)](i) increases were also inhibited following exposure to high drug concentrations, although drugs were less potent on this endpoint. Our data demonstrate that at high drug concentrations all tested drugs reduce stimulation-evoked increases in [Ca(2+)](i), thereby probably reducing dopaminergic output through inhibition of electrical and cholinergic input. Furthermore, the increases in basal [Ca(2+)](i) at high concentrations of MDMA and mCPP likely increases dopaminergic output. Similarly, the increases in ACh-evoked [Ca(2+)](i) upon cholinergic stimulation following exposure to low concentrations of amphetamines can contribute to drug-induced increases in DA levels observed in vivo. Finally, this study shows that mCPP, which is regularly found in ecstasy tablets, is the most potent drug regarding the investigated endpoints