3,4-Methylenedioxypyrovalerone (MDPV) and metabolites quantification in human and rat plasma by liquid chromatography-high resolution mass spectrometry

Dual-binding domain electrochemiluminescence biosensing platform with self-checking function for sensitive detection of synthetic cathinone in e-cigarettes

Current single signal electrochemiluminescence (ECL) sensors are susceptible to false positive or false negative phenomena due to experimental conditions. Therefore, sensors with "self-checking" function are attracting democratic attention. In quick succession, a highly sensitive single-cathode dual ECL signal aptasensor with self-checking function to improve the shortcomings mentioned above was designed. This aptasensor used In-based metal-organic framework (MIL-68) as load and stabilizer to effectively attenuate the aggregation-induced quenching (ACQ) effect of porphyrin derivatives (Sn-TCPP) while improve ECL stability. The introduction of cooperative-binding split-aptamers" (CBSAs) aptamers increased the specificity of the aptasensor and its unique double-binding domains detection accelerated the detection efficiency. When analyzing 3,4-methylenedioxypyrovalerone (MDPV), we could calculate two concentrations based on the strength of ECL 1 and ECL 2. If the concentrations are the same, the result would be obtained; if not, it should be retested. Depending on the above operation, the results achieve self-check. It was found that the designed aptasensor could quantify the concentration of MDPV between 1.0 × 10^-12 g/L and 1.0 × 10^-6 g/L with the limit of detection (LOD) of 1.4 × 10^-13 g/L and 2.0 × 10^-13 g/L, respectively (3 σ/slope). This study not only improves the detection technology of MDPV, but also explores the dual-signal detection of porphyrin for the first time and enriches the definition of self-checking sensor.

Quantification of Cathinone Analogues without Reference Standard Using 1H Quantitative NMR

Synthetic cathinones are a type of new psychoactive substances (NPS) that have been seriously abused. Owing to the rapid variation in their structures, the absence of reference standards poses a challenge in quantitative investigations. In this study, a ¹H quantitative nuclear magnetic resonance (¹H qNMR) method was established using maleic acid as the internal standard and the shared signal (i.e., the methylidyne hydrogen) on the parent synthetic cathinones structure as the quantitative peak. Taking 3-methoxy-2-(methylamino)-1-(4-methylphenyl)propan-1-one (mexedrone) as an example, this study optimized the acquisition parameters and conducted method validation, including an evaluation of the specificity, linearity, accuracy, precision, and robustness. Using this ¹H qNMR method, the contents of mexedrone and its analogues, including 1-(3-chlorophenyl)-2-(ethylamino)-propan-1-one (3-CEC), 4-chloro-α-pyrroli-dinopropiophenone (4-Cl-α-PVP), 1-(3,4-methylenedioxy-phenyl)-2-propylamino-propan-1-one (propylone), and methcathinone, were obtained. The obtained results showed that the method was accurate, rapid, versatile, and can be used to address the qualitative and quantitative issues related to similar substances.

Occurrence, bioaccumulation and toxicological effect of drugs of abuse in aquatic ecosystem: A review

Drugs of abuse are a group of emerging contaminants. As the prevalence of manufacture and consumption, there is a growing global environmental burden and ecological risk from the continuous release of these contaminants into environment. The widespread occurrence of drugs of abuse in waste wasters and surface waters is due to the incomplete removal through traditional wastewater treatment plants in different regions around the world. Although their environmental concentrations are not very high, they can potentially influence the aquatic organisms and ecosystem function. This paper reviews the occurrence of drugs of abuse and their metabolites in waste waters and surface waters, their bioaccumulation in aquatic plants, fishes and benthic organisms and even top predators, and the toxicological effects such as genotoxic effect, cytotoxic effect and even behavioral effect on aquatic organisms. In summary, drugs of abuse occur widely in aquatic environment, and may exert adverse impact on aquatic organisms at molecular, cellular or individual level, and even on aquatic ecosystem. It necessitates the monitoring and risk assessment of these compounds on diverse aquatic organisms in the further study.

Naphyrone (naphthylpyrovalerone): Pharmacokinetics, behavioural effects and thermoregulation in Wistar rats

Naphthylpyrovalerone (naphyrone) is a pyrovalerone cathinone that potently inhibits monoamine transporters and provides stimulatory-entactogenic effects. Little is known about the safety of naphyrone or its effects in vivo, and more research is needed to acquire knowledge about its fundamental effects on physiology and behaviour. Our objective was to investigate naphyrone's pharmacokinetics, acute toxicity, hyperthermic potential and stimulatory and psychotomimetic properties in vivo in male Wistar rats. Pharmacokinetics after 1 mg/kg subcutaneous (sc.) naphyrone were measured over 6 h in serum, the brain, liver and lungs. Rectal temperature (degree Celsius) was measured over 10 h in group-versus individually housed rats after 20 mg/kg sc. In the behavioural experiments, 5, 10 or 20 mg/kg of naphyrone was administered 15 or 60 min prior to testing. Stimulation was assessed in the open field, and sensorimotor processing in a prepulse inhibition (PPI) task. Peak concentrations of naphyrone in serum and tissue were reached at 30 min, with a long-lasting elevation in the brain/serum ratio, consistent with observations of lasting hyperlocomotion in the open field and modest increases in body temperature. Administration of 20 mg/kg transiently enhanced PPI. Naphyrone crosses the blood-brain barrier rapidly and is eliminated slowly, and its long-lasting effects correspond to its pharmacokinetics. No specific signs of acute toxicity were observed; therefore, clinical care and harm-reduction guidance should be in line with that available for other stimulants and cathinones.

3,4-Methylenedioxypyrovalerone (MDPV) Sensing Based on Electropolymerized Molecularly Imprinted Polymers on Silver Nanoparticles and Carboxylated Multi-Walled Carbon Nanotubes

3,4-methylenedioxypyrovalerone (MDPV) is a harmful and controlled synthetic cathinone used as a psychostimulant drug and as sport-enhancing substance. A sensor was developed for the direct analysis of MDPV by transducing its oxidation signal by means of an electropolymerized molecularly imprinted polymer (e-MIP) built in-situ on the screen-printed carbon electrode's (SPCE) surface previously covered with multi-walled carbon nanotubes (MWCNTs) and silver nanoparticles (AgNPs). Benzene-1,2-diamine was used as the functional monomer while the analyte was used as the template monomer. Each step of the sensor's development was studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a solution containing ferricyanide, however no redox probe was required for the actual MDPV measurements. The interaction between the poly(o-phenylenediamine) imprinted polymer and MDPV was studied by density-functional theory (DFT) methods. The SPCE-MWCNT-AgNP-MIP sensor responded adequately to the variation of MDPV concentration. It was shown that AgNPs enhanced the electrochemical signal by around a 3-fold factor. Making use of square-wave voltammetry (SWV) the developed sensor provided a limit of detection (LOD) of 1.8 μmol L-1. The analytical performance of the proposed sensor paves the way to the development of a portable device for MDPV on-site sensing to be applied in forensic and doping analysis.

Development and validation of GC-MS method for determination of methcathinone and its main metabolite in mice plasma and brain tissue after SPE: Pharmacokinetic and distribution study

Only focusing on the plasma levels is inadequate for the full consideration of the physiological disposition of illicit drugs in vivo. Therefore, we conducted the inclusive study on the in vivo dynamic process of intraperitoneal administration of methcathinone (MET), a well-known member of the synthetic cathinone derivatives, which is structurally similar to amphetamine analogs. This study described a validated, selective and sensitive GC-MS method for the simultaneous quantification of MET and its main metabolite, ephedrine (EPD), in the plasma and brain tissue of mice, after solid phase extraction (SPE). Ephedrine-d3 was used as an internal standard (IS). The developed method was validated following US-FDA guidelines within a concentration range of 5-1000 ng/mL for both drugs (r2 > 0.998) in the mice plasma and brain. The recoveries of MET and EPD from the mice plasma and brain ranged from 108.5 to 112.1%. The intra- and inter-day RSDs were ≤ 11.0 %. The proposed method was applied, for the first time, to investigate the pharmacokinetic (PK) and distribution study of MET and EPD following intraperitoneal administration of MET (1.4 mg/kg) to Swiss albino mice. The results exhibited that the C_max and T_max of MET in mice plasma was 517.1 ng/mL and 15 min as compared to 3.6 ng/mL and 2 h of EPD. Moreover, MET rapidly passed the blood brain barrier with C_max of 1444.5 ng/mL achieved at 15 min, whereas, EPD monitored C_max of 43.6 ng/mL at 4 h in mice brain. The highest concentration of MET in the mice brain followed by plasma was reported, with a necessity to perform more detailed clinical investigations.

Effect of temperature on 3,4-Methylenedioxypyrovalerone (MDPV)-induced metabolome disruption in primary mouse hepatic cells

3,4-Methylenedioxypyrovalerone (MDPV) is one of the most popular cathinone derivatives worldwide and has recently been associated with several intoxications and deaths, in which, similarly to amphetamines, hyperthermia appears to play a prominent role. However, there remains a huge information gap underlying the mechanisms associated with its hepatotoxicity, namely under hyperthermic conditions. Here, we use a sensitive untargeted metabolomic approach based on gas chromatography-mass spectrometry (GC-MS) to investigate the effect of subtoxic and toxic concentrations of MDPV on the metabolic profile of primary mouse hepatocytes (PMH), under normothermic and hyperthermic conditions. For this purpose, hepatocytes were exposed to increasing concentrations of MDPV (LC₀₁, LC₁₀ and LC₃₀) for 24 h, at 37 °C or 40.5 °C, and alterations on both intracellular metabolome and extracellular volatilome were evaluated. Multivariate analysis showed a clear separation between MDPV exposed cells and control cells in normothermic conditions, even at subtoxic concentrations (LC₀₁ and LC₁₀). In normothermia, there was a significant dysregulation of pathways associated with ascorbate metabolism, tricarboxylic acid (TCA) cycle and pyruvate metabolism. These metabolic changes were significantly increased at 40.5 °C, and several other pathways appear to be affected with the evolution of toxicity caused by MDPV under hyperthermic conditions, namely aspartate and glutamate metabolism, phenylalanine and tyrosine biosynthesis, aminoacyl-tRNA biosynthesis, butanoate metabolism, among others. Overall, our findings provide novel insights into the mechanism of hepatotoxicity triggered by MDPV and highlight the higher risks that may occur under hyperthermic conditions.

Metabolites of the ring-substituted stimulants MDMA, methylone and MDPV differentially affect human monoaminergic systems

BACKGROUND

Amphetamine analogs with a 3,4-methylenedioxy ring-substitution are among the most popular illicit drugs of abuse, exerting stimulant and entactogenic effects. Enzymatic N-demethylation or opening of the 3,4-methylenedioxy ring via O-demethylenation gives rise to metabolites that may be pharmacologically active. Indeed, previous studies in rats show that specific metabolites of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxymethcathinone (methylone) and 3,4-methylenedioxypyrovalerone (MDPV) can interact with monoaminergic systems.

AIM

Interactions of metabolites of MDMA, methylone and MDPV with human monoaminergic systems were assessed.

METHODS

The ability of parent drugs and their metabolites to inhibit uptake of tritiated norepinephrine, dopamine and serotonin (5-HT) was assessed in human embryonic kidney 293 cells transfected with human monoamine transporters. Binding affinities and functional activity at monoamine transporters and various receptor subtypes were also determined.

RESULTS

MDMA and methylone displayed greater potency to inhibit norepinephrine uptake as compared to their effects on dopamine and 5-HT uptake. N-demethylation of MDMA failed to alter uptake inhibition profiles, whereas N-demethylation of methylone decreased overall transporter inhibition potencies. O-demethylenation of MDMA, methylone and MDPV resulted in catechol metabolites that maintained norepinephrine and dopamine uptake inhibition potencies, but markedly reduced activity at 5-HT uptake. O-methylation of the catechol metabolites significantly decreased norepinephrine uptake inhibition, resulting in metabolites lacking significant stimulant properties.

CONCLUSIONS

Several metabolites of MDMA, methylone and MDPV interact with human transporters and receptors at pharmacologically relevant concentrations. In particular, N-demethylated metabolites of MDMA and methylone circulate in unconjugated form and could contribute to the in vivo activity of the parent compounds in human users.

Pharmacokinetic data of synthetic cathinones in female Sprague-Dawley rats

The synthetic cathinones methylone, butylone, and pentylone differ from each other through the one carbon lengthening of the α-alkyl chain: methylone (-CH3), butylone (-CH2CH3), and pentylone (-CH2CH2CH3) while 3,4-methylenedioxymethamphetamine (MDMA) differs from methylone by a single oxygen atom. Studies with MDMA, suggests that there may be male and female pharmacokinetic and pharmacodynamic differences. In the present study, we present the plasma pharmacokinetic data relative to a 20 mg/kg, subcutaneous doses of methylone, butylone and pentylone in female Sprague-Dawley rats. Briefly, plasma samples were collected via a jugular vein cannula, purified, and analyzed using a HPLC system. While we have previously reported on the consistent relationship between structure and pharmacokinetics of these synthetic cathinones in male, Sprague-Dawley rats (Grecco and Sprague, 2016), this data set suggests that there is no consistent relationship of chemical structure and pharmacokinetics of methylone, butylone and pentylone in female Sprague-Dawley rats. The findings from the present study further emphasize the need for the inclusion of female subjects in the pharmacokinetic studies of synthetic cathinones as it is very possible male-female differences may exist in rodent models.

Behavioural, Pharmacokinetic, Metabolic, and Hyperthermic Profile of 3,4-Methylenedioxypyrovalerone (MDPV) in the Wistar Rat

3,4-methylenedioxypyrovalerone (MDPV) is a potent pyrovalerone cathinone that is substituted for amphetamines by recreational users. We report a comprehensive and detailed description of the effects of subcutaneous MDPV (1-4 mg/kg) on pharmacokinetics, biodistribution and metabolism, acute effects on thermoregulation under isolated and aggregated conditions, locomotion (open field) and sensory gating (prepulse inhibition, PPI). All studies used male Wistar rats. Pharmacokinetics after single dose of 2 mg/kg MDPV was measured over 6 h in serum, brain and lungs. The biotransformation study recorded 24 h urinary levels of MDPV and its metabolites after 4 mg/kg. The effect of 2 mg/kg and 4 mg/kg on body temperature (°C) was measured over 12 h in group- vs. individually-housed rats. In the open field, locomotion (cm) and its spatial distribution were assessed. In PPI, acoustic startle response (ASR), habituation, and PPI were measured (AVG amplitudes). In behavioural experiments, 1, 2, or 4 mg/kg MDPV was administered 15 or 60 min prior to testing. Thermoregulation and behavioural data were analysed using factorial analysis of variance (ANOVA). Peak concentrations of MDPV in sera, lung and brain tissue were reached in under 30 min. While negligible levels of metabolites were detected in tissues, the major metabolites in urine were demethylenyl-MDPV and demethylenyl-methyl-MDPV at levels three-four times higher than the parent drug. We also established a MDPV brain/serum ratio ~2 lasting for ~120 min, consistent with our behavioural observations of locomotor activation and disrupted spatial distribution of behaviour as well as moderate increases in body temperature (exacerbated in group-housed animals). Finally, 4 mg/kg induced stereotypy in the open field and transiently disrupted PPI. Our findings, along with previous research suggest that MDPV is rapidly absorbed, readily crosses the blood-brain barrier and is excreted primarily as metabolites. MDPV acts as a typical stimulant with modest hyperthermic and psychomimetic properties, consistent with a primarily dopaminergic mechanism of action. Since no specific signs of acute toxicity were observed, even at the highest doses used, clinical care and harm-reduction guidance should be in line with that available for other stimulants and cathinones.

The combination of MDPV and ethanol results in decreased cathinone and increased alcohol levels. Study of such pharmacological interaction

Methylenedioxypyrovalerone (MDPV) is a new psychostimulant cathinone acting as a selective dopamine transporter blocker. Due to the concomitant consumption of ethanol (EtOH) and new psychoactive substances, it is of interest to explore a possible pharmacological interaction between MDPV and EtOH. In locomotor activity assays, EtOH (1g/kg i.p.) elicited a reduction in the stimulant effect induced by low doses of MDPV (0.1-0.3mg/kg, s.c.) in rats, jointly with a decrease in blood and brain MDPV concentrations. Experiments in rat liver microsomes showed different effects depending on the [MDPV]/[EtOH] relationship, evidencing, at certain concentrations, the enhancing effect of EtOH on MDPV metabolism. These suggest that EtOH interacts with MDPV at microsomal level, increasing its metabolic rate. The interaction between both substances was also supported by results in plasma EtOH concentration, which were significantly increased by MDPV, in such a manner that EtOH elimination rate was significantly reduced. The possible toxicological impact of this phenomenon deserves further investigation. In contrast, the rewarding properties of MDPV were unaltered by EtOH. Microdialysis experiments verified that, in the NAcc, both substances could also act synergistically, in such a manner that extracellular dopamine concentrations are maintained. Finally, if the psychostimulant effect induced by MDPV decreased with EtOH, it could favor the boosting and re-dosing in search of the desired effects. However, as the rewarding effect of each dose of the substance would not decrease, the addictive liability could increase considerably. Moreover, we must warn about the increase in EtOH concentrations when consumed concomitantly with MDPV.

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 C_max and AUC_0-∞, and the longest t_1/2. Decreasing the α-alkyl chain length as in butylone and methylone significantly decreased the C_max, AUC_0-∞, and t_1/2. 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 C_max and AUC_0-∞ 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.

Toxicological investigation of forensic cases related to the designer drug 3,4-methylenedioxypyrovalerone (MDPV): Detection, quantification and studies on human metabolism by GC-MS

3,4-methylenedioxypyrovalerone (MDPV) is a synthetic cathinone belonging to the class of α-pyrrolidinophenones that become increasingly popular as a designer psychostimulant. Here, we report a comprehensive collection of MDPV exposure with quantitative serum level confirmation in Germany. During the years 2014-2016, we could proof consumption of MDPV in 23 cases where urine and blood samples were submitted to our laboratory by the police of Lower Saxony. Most of the samples underwent systematic toxicological analysis by gas chromatography-mass spectrometry (GC-MS), where MDPV could be detected in urine and/or serum samples. The determined concentrations of MDPV in serum showed a high variability, ranging from traces (<10ng/mL) up to 576ng/mL with a mean concentration of 118ng/mL and median of 47ng/mL. The majority of MDPV users were men (87%) and the age ranged from 23 to 49 years (mean 35.9, median 37 years). For most of the analytically confirmed MDPV cases we could prove co-consumption of other psychotropic drugs with frequent occurrence of opiates and cannabinoids in 22% of the cases, followed by benzodiazepines and cocaine in 17%. Analysis of urine samples by GC-MS disclosed the presence of MDPV and its metabolites 2'-oxo-MDPV, demethylenyl-MDPV, demethylenyl-methyl-MDPV, demethylenyl-oxo-MDPV, demethylenyl-methyl-oxo-MDPV and demethylenyl-methyl-N,N-bisdealkyl-MDPV. The metabolite pattern substantiates previous suggestions for principle metabolic pathways of MDPV in humans.

Chiral determination of 3,4-methylenedioxypyrovalerone enantiomers in rat serum

The emerging stimulant drug of abuse (3,4)-methylenedioxypyrovalerone [(R,S)-MDPV] is self-administered as a racemic mixture by intranasal, iv, oral, and smoking routes. The individual enantiomers are known to have widely different pharmacological effects, with (S)-MDPV showing much greater potency than (R)-MDPV in pharmacological testing. The goal of these studies was to develop and validate an analytical method for quantitation of (R)-MDPV, (S)-MDPV and (R,S)-MDPV in small volumes of rat serum using a chiral separation column and liquid chromatography-mass spectrometry. The method was validated for selectivity, precision, accuracy, recovery, sensitivity, and reproducibility. The method was also used to determine the enantiomeric stability of the individual enantiomers during sample cleanup and analysis. The linear dynamic range of the calibration curve was 1 - 1000 ng/ml for each enantiomer. Concentration values for the lower limit of quantitation (1 ng/ml) were within 30% of their nominal value, but all other calibration standards were <20% of their nominal value. With proper storage and handling of samples, the two MDPV enantiomers were shown to remain stable in rat serum without any apparent racemization during the time needed for analysis. Finally, the ruggedness of the method was demonstrated with diluted and undiluted serum samples collected from Sprague Dawley rats in a preliminary pharmacokinetic study at 3 mg/kg of (R,S)-MDPV. In summary, the assay used a simple sample preparation method, reversed-phase chiral chromatography, and tandem mass spectrometry to achieve accurate and selective determinations of MDPV enantiomer concentrations in small volumes of serum.

Neuropharmacology of 3,4-Methylenedioxypyrovalerone (MDPV), Its Metabolites, and Related Analogs

3,4-Methylenedioxypyrovalerone (MDPV) is a psychoactive component of so-called bath salts products that has caused serious medical consequences in humans. In this chapter, we review the neuropharmacology of MDPV and related analogs, and supplement the discussion with new results from our preclinical experiments. MDPV acts as a potent uptake inhibitor at plasma membrane transporters for dopamine (DAT) and norepinephrine (NET) in nervous tissue. The MDPV formulation in bath salts is a racemic mixture, and the S isomer is much more potent than the R isomer at blocking DAT and producing abuse-related effects. Elevations in brain extracellular dopamine produced by MDPV are likely to underlie its locomotor stimulant and addictive properties. MDPV displays rapid pharmacokinetics when injected into rats (0.5-2.0 mg/kg), with peak plasma concentrations achieved by 10-20 min and declining quickly thereafter. MDPV is metabolized to 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) in vivo, but motor activation produced by the drug is positively correlated with plasma concentrations of parent drug and not its metabolites. 3,4-Catechol-PV is a potent uptake blocker at DAT in vitro but has little activity after administration in vivo. 4-OH-3-MeO-PV is the main MDPV metabolite but is weak at DAT and NET. MDPV analogs, such as α-pyrrolidinovalerophenone (α-PVP), display similar ability to inhibit DAT and increase extracellular dopamine concentrations. Taken together, these findings demonstrate that MDPV and its analogs represent a unique class of transporter inhibitors with a high propensity for abuse and addiction.

Active vaccination attenuates the psychostimulant effects of α-PVP and MDPV in rats

Recreational use of substituted cathinones continues to be an emerging public health problem in the United States; cathinone derivatives α-pyrrolidinopentiophenone (α-PVP) and 3,4-methylenedioxypyrovalerone (MDPV), which have been linked to human fatalities and show high potential for abuse liability in animal models, are of particular concern. The objective of this study was to develop an immunotherapeutic strategy for attenuating the effects of α-PVP and MDPV in rats, using drug-conjugate vaccines created to generate antibodies with neutralizing capacity. Immunoconjugates (α-PVP-KLH and MDPV-KLH) or the control carrier protein, keyhole limpet hemocyanin (KLH), were administered to groups (N = 12) of male Sprague-Dawley rats on Weeks 0, 2 and 4. Groups were administered α-PVP or MDPV (0.0, 0.25, 0.5, 1.0, 5.0 mg/kg, i.p.) in acute drug challenges and tested for changes in wheel activity. Increased wheel activity produced by α-PVP or MDPV in the controls was attenuated in the α-PVP-KLH and MDPV-KLH vaccinated groups, respectively. Rectal temperature decreases produced by MDPV in the controls were reduced in duration in the MDPV-KLH vaccine group. A separate group (N = 19) was trained to intravenously self-administer α-PVP (0.05, 0.1 mg/kg/inf) and vaccinated with KLH or α-PVP-KLH, post-acquisition. Self-administration in α-PVP-KLH rats was initially higher than in the KLH rats but then significantly decreased following a final vaccine booster, unlike the stable intake of KLH rats. The data demonstrate that active vaccination provides functional protection against the effects of α-PVP and MDPV, in vivo, and recommend additional development of vaccines as potential therapeutics for mitigating the effects of designer cathinone derivatives.

Pharmacological mechanisms underlying the cardiovascular effects of the "bath salt" constituent 3,4-methylenedioxypyrovalerone (MDPV)

BACKGROUND AND PURPOSE

3,4-Methylenedioxypyrovalerone (MDPV) is a synthetic cathinone with stimulatory cardiovascular effects that can lead to serious medical complications. Here, we examined the pharmacological mechanisms underlying these cardiovascular actions of MDPV in conscious rats.

EXPERIMENTAL APPROACH

Male Sprague-Dawley rats had telemetry transmitters surgically implanted for the measurement of BP and heart rate (HR). On test days, rats were placed individually in standard isolation cubicles. Following drug treatment, cardiovascular parameters were monitored for 3 h sessions.

KEY RESULTS

Racemic MDPV (0.3-3.0 mg·kg^-1 ) increased BP and HR in a dose-dependent manner. The S(+) enantiomer (0.3-3.0 mg·kg^-1 ) of MDPV produced similar effects, while the R(-) enantiomer (0.3-3.0 mg·kg^-1 ) had no effects. Neither of the hydroxylated phase I metabolites of MDPV altered cardiovascular parameters significantly from baseline. Pretreatment with the ganglionic blocker chlorisondamine (1 and 3 mg·kg^-1 ) antagonized the increases in BP and HR produced by 1 mg·kg^-1 MDPV. The α₁ -adrenoceptor antagonist prazosin (0.3 mg·kg^-1 ) attenuated the increase in BP following MDPV, while the β-adrenoceptor antagonists propranolol (1 mg·kg^-1 ) and atenolol (1 and 3 mg·kg^-1 ) attenuated the HR increases.

CONCLUSIONS AND IMPLICATIONS

The S(+) enantiomer appeared to mediate the cardiovascular effects of MDPV, while the metabolites of MDPV did not alter BP or HR significantly; MDPV increased BP and HR through activation of central sympathetic outflow. Mixed-action α/β-adrenoceptor antagonists may be useful as treatments in counteracting the adverse cardiovascular effects of MDPV.

Quantification of Synthetic Cathinones in Rat Brain Using HILIC-ESI-MS/MS

The abuse of synthetic cathinones, formerly marketed as "bath salts", has emerged over the last decade. Three common drugs in this class include 3,4-methylenedioxypyrovalerone (MDPV), 4-methylmethcathinone (mephedrone), and 3,4-methylenedioxymethcathinone (methylone). An LC-MS/MS method has been developed and validated for the simultaneous quantification of MDPV, mephedrone, and methylone in brain tissue. Briefly, MDPV, mephedrone, methylone, and their deuterium-labeled analogs were subjected to solid phase extraction (SPE) and separated using an HILIC Silica Column. The HPLC was coupled to a Shimadzu IT-TOF (ion trap-time of flight) system with the electrospray source running in positive mode (+ESI). The method was validated for precision, accuracy, and extraction efficiency. All inter-day and intra-day % RSD (percent relative standard deviation) and % error values were less than 15% and extraction efficiency exceeded 80%. These conditions allowed for limits of detection of 1ng/mL for MDPV, and 5 ng/mL for both mephedrone and methylone. The limits of quantification were determined to be 5ng/mL for MDPV and 10 ng/mL for mephedrone and methylone. The method was utilized to evaluate the pharmacokinetics of these drugs in adult male rats following administration of a drug cocktail including MDPV, mephedrone, and methylone. All three compounds reached peak concentrations in the brain within 15 min. Although methylone and mephedrone were administered at the same dose, the peak concentration (Cmax) of mephedrone in the brain was significantly higher than that for methylone, as was the area under the curve (AUC). In summary, this quick and sensitive method for measuring synthetic cathinones may be used for future pharmacokinetic investigations of these drugs in target tissue.

Characterization of in vitro metabolites of methylenedioxypyrovalerone (MDPV): An N-oxide metabolite formation mediated by flavin monooxygenase

Methylenedioxypyrovalerone (MDPV) has emerged in recent years as a recreational substance with psychostimulant properties. In this study, in vitro metabolites of MDPV were characterized based on liquid chromatography/quadrupole-time-of-flight mass spectrometry (LC/QTOF MS). MDPV was incubated with human liver microsomes, human recombinant cDNA-expressed cytochrome P450 enzymes and flavin monooxygenase (FMO). MDPV was metabolized to yield eight metabolites (M1-M8) with major metabolic reactions such as demethylenation and oxidation. Among them, M6 was assigned as an N-oxide metabolite. FMO was found to be a principal enzyme responsible for the formation of M6; FMO1 and FMO3 were the main enzymes involved in N-oxidation of MDPV.

Synthetic cathinone pharmacokinetics, analytical methods, and toxicological findings from human performance and postmortem cases

Synthetic cathinones are commonly abused novel psychoactive substances (NPS). We present a comprehensive systematic review addressing in vitro and in vivo synthetic cathinone pharmacokinetics, analytical methods for detection and quantification in biological matrices, and toxicological findings from human performance and postmortem toxicology cases. Few preclinical administration studies examined synthetic cathinone pharmacokinetic profiles (absorption, distribution, metabolism, and excretion), and only one investigated metabolite pharmacokinetics. Synthetic cathinone metabolic profiling studies, primarily with human liver microsomes, elucidated metabolite structures and identified suitable biomarkers to extend detection windows beyond those provided by parent compounds. Generally, cathinone derivatives underwent ketone reduction, carbonylation of the pyrrolidine ring, and oxidative reactions, with phase II metabolites also detected. Reliable analytical methods are necessary for cathinone identification in biological matrices to document intake and link adverse events to specific compounds and concentrations. NPS analytical methods are constrained in their ability to detect new emerging synthetic cathinones due to limited commercially available reference standards and continuous development of new analogs. Immunoassay screening methods are especially affected, but also gas-chromatography and liquid-chromatography mass spectrometry confirmation methods. Non-targeted high-resolution-mass spectrometry screening methods are advantageous, as they allow for retrospective data analysis and easier addition of new synthetic cathinones to existing methods. Lack of controlled administration studies in humans complicate interpretation of synthetic cathinones in biological matrices, as dosing information is typically unknown. Furthermore, antemortem and postmortem concentrations often overlap and the presence of other psychoactive substances are typically found in combination with cathinones derivatives, further confounding result interpretation.

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.

Determination of 3,4-methylenedioxypyrovalerone (MDPV) in oral and nasal fluids by ion mobility spectrometry

A fast and sensitive methodology has been developed for the evaluation of the 3,4-methylenedioxypyrovalerone (MDPV) consumed. Based on ion mobility spectrometry (IMS), MDPV was directly determined in nasal fluids with a limit of detection (LOD) in the order of 22 ng mL(-1), which corresponds to an absolute amount of 33 ng of MDPV per swab. MDPV was also determined after liquid-liquid microextraction (LLME) in oral fluids to avoid matrix effects, obtaining a LOD value of 4.4 ng mL(-1) in oral fluid samples. The IMS spectrum for MDPV exhibited a peak with K0 = 1.210 ± 0.005 cm(2)V(-1) s(-1) at a drift time of 14.62 ms, the total analysis time being 4.5 min per oral fluid and 1.5 min per nasal fluid sample. Samples must be analyzed within 24 h following collection and dissolution in 2-propanol, based on the complementary stability studies.

Concentrations of MDPV in rat striatum correlate with the psychostimulant effect

3,4-methylenedioxypyrovalerone or MDPV is a synthetic cathinone with psychostimulant properties more potent than cocaine. We quantified this drug in the striatum after subcutaneous administration to rats. MDPV reached the brain around 5 min after its administration and peaked at 20-25 min later. The elimination half-life in the striatum (61 min) correlates with the decrease in the psychostimulant effect after 60 min. Around 11% of the administered dose reached the striatum and, considering a homogeneous brain distribution, we determined that around 86% of the plasma MDPV is distributed to the brain. MDPV induced a dose-dependent increase in locomotor activity, rearing behaviour and stereotypies, all prevented by haloperidol. A plot of locomotor activity or stereotypies versus MDPV striatal concentrations over time showed a direct relationship between factors. No free MDPV metabolites were detected in plasma, at any time, but hydrolysis with glucuronidase allowed us to identify mainly three metabolites, one of them for the first time in rat plasma. The present results contribute to evidence that MDPV induces hyperlocomotion mainly through a dopamine-dependent mechanism. Good correlation between behavioural effects and striatal levels of MDPV leads us to conclude that its psychostimulant effect is mainly due to a striatal distribution of the substance. The present research provides useful information on the pharmacokinetics of MDPV, and can help design new experiments with kinetics data as well as provide a better understanding of the effects of MDPV in humans and its potential interactions.

In vitro Phase I and Phase II metabolism of α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV) and methedrone by human liver microsomes and human liver cytosol

The aim of the present study was to identify the in vitro Phase I and Phase II metabolites of three new psychoactive substances: α-pyrrolidinovalerophenone (α-PVP), methylenedioxypyrovalerone (MDPV), and methedrone, using human liver microsomes and human liver cytosol. Accurate-mass spectra of metabolites were obtained using liquid chromatography-quadrupole time-of-flight mass spectrometry. Six Phase I metabolites of α-PVP were identified, which were formed involving reduction, hydroxylation, and pyrrolidine ring opening reactions. The lactam compound was the major metabolite observed for α-PVP. Two glucuronidated metabolites of α-PVP, not reported in previous in vitro studies, were further identified. MDPV was transformed into 10 Phase I metabolites involving reduction, hydroxylation, and loss of the pyrrolidine ring. Also, six glucuronidated and two sulphated metabolites were detected. The major metabolite of MDPV was the catechol metabolite. Methedrone was transformed into five Phase I metabolites, involving N- and O-demethylation, hydroxylation, and reduction of the ketone group. Three metabolites of methedrone are reported for the first time. In addition, the contribution of individual human CYP enzymes in the formation of the detected metabolites was investigated.

Detection and quantification of 56 new psychoactive substances in whole blood and urine by LC–MS/MS

Background: New psychoactive substances (NPS) have become increasingly prevalent and are sold in internet shops as ‘bath salts’ or ‘research chemicals’ and comprehensive bioanalytical methods are needed for their detection. Methodology: We developed and validated a method using LC and MS/MS to quantify 56 NPS in blood and urine, including amphetamine derivatives, 2C compounds, aminoindanes, cathinones, piperazines, tryptamines, dissociatives and others. Instrumentation included a Synergi Polar-RP column (Phenomenex) and a 3200 QTrap mass spectrometer (AB Sciex). Run time was 20 min. Conclusion: A novel method is presented for the unambiguous identification and quantification of 56 NPS in blood and urine samples in clinical and forensic cases, e.g., intoxications or driving under the influence of drugs.

Comprehensive review of the detection methods for synthetic cannabinoids and cathinones

A number of N-alkyl indole or indazole-3-carbonyl analogs, with modified chemical structures, are distributed throughout the world as synthetic cannabinoids. Like synthetic cannabinoids, cathinone analogs are also abused and cause serious problems worldwide. Acute deaths caused by overdoses of these drugs have been reported. Various analytical methods that can cope with the rapid changes in chemical structures are required for routine analysis and screening of these drugs in seized and biological materials for forensic and clinical purposes. Although many chromatographic methods to analyze each drug have been published, there are only a few articles summarizing these analytical methods. This review presents the various colorimetric detections, immunochemical assays, gas chromatographic-mass spectrometric methods, and liquid chromatographic-mass spectrometric methods proposed for the analysis of synthetic cannabinoids and cathinones.

Comprehensive review of the detection methods for synthetic cannabinoids and cathinones

A number of N-alkyl indole or indazole-3-carbonyl analogs, with modified chemical structures, are distributed throughout the world as synthetic cannabinoids. Like synthetic cannabinoids, cathinone analogs are also abused and cause serious problems worldwide. Acute deaths caused by overdoses of these drugs have been reported. Various analytical methods that can cope with the rapid changes in chemical structures are required for routine analysis and screening of these drugs in seized and biological materials for forensic and clinical purposes. Although many chromatographic methods to analyze each drug have been published, there are only a few articles summarizing these analytical methods. This review presents the various colorimetric detections, immunochemical assays, gas chromatographic-mass spectrometric methods, and liquid chromatographic-mass spectrometric methods proposed for the analysis of synthetic cannabinoids and cathinones.

Baths salts, spice, and related designer drugs: the science behind the headlines

The abuse of synthetic psychoactive substances known as "designer drugs," or "new psychoactive substances" (NPS), is increasing at an alarming rate. NPS are purchased as alternatives to traditional illicit drugs of abuse and are manufactured to circumvent laws regulating the sale and use of controlled substances. Synthetic cathinones (i.e., "bath salts") and synthetic cannabinoids (i.e., "spice") are two types of NPS that have received substantial media attention. Although low recreational doses of bath salts or spice compounds can produce desirable effects, high doses or chronic exposure often leads to dangerous medical consequences, including psychosis, violent behaviors, tachycardia, hyperthermia, and even death. Despite the popularity of NPS, there is a paucity of scientific data about these drugs. Here we provide a brief up-to-date review describing the mechanisms of action and neurobiological effects of synthetic cathinones and cannabinoids.