Aminorex, a metabolite of the cocaine adulterant levamisole, exerts amphetamine like actions at monoamine transporters

Levamisole Impairs Vascular Function by Blocking α-Adrenergic Receptors and Reducing NO Bioavailability in Rabbit Renal Artery

Levamisole is an anthelmintic drug restricted to veterinary use but is currently detected as the most widely used cocaine cutting agent in European countries. Levamisole-adulterated cocaine has been linked to acute kidney injury, marked by a decrease in glomerular filtration rate, which involves reduced renal blood flow, but data on the alteration of renovascular response produced by levamisole are scarce. Renal arteries were isolated from healthy rabbits and used for isometric tension recording in organ baths and protein analysis. We provide evidence that depending on its concentration, levamisole modulates renovascular tone by acting as a non-selective α-adrenergic receptor blocker and down-regulates α1-adrenoceptor expression. Furthermore, levamisole impairs the endothelium-dependent relaxation induced by acetylcholine without modifying endothelial nitric oxide synthase (eNOS) expression. However, exposure to superoxide dismutase (SOD) partially prevents the impairment of ACh-induced relaxation by levamisole. This response is consistent with a down-regulation of SOD1 and an up-regulation of NADPH oxidase 4 (Nox4), suggesting that endothelial NO loss is due to increased local oxidative stress. Our findings demonstrate that levamisole can interfere with renal blood flow and the coordinated response to a vasodilator stimulus, which could worsen the deleterious consequences of cocaine use.

In vitro and in silico investigation of FDA-approved drugs to be repurposed against Alzheimer's disease

Alzheimer's disease (AD), one of the main causes of dementia, is a neurodegenerative disorder. Cholinesterase inhibitors are used in the treatment of AD, but prolonged use of these drugs can lead to serious side effects. Drug repurposing is an approach that aims to reveal the effectiveness of drugs in different diseases beyond their clinical uses. In this work, we investigated in vitro and in silico inhibitory effects of 11 different drugs on cholinesterases. The results showed that trimebutine, theophylline, and levamisole had the highest acetylcholinesterase inhibitory actions among the tested drugs, and these drugs inhibited by 68.70 ± 0.46, 53.25 ± 3.40, and 44.03 ± 1.20%, respectively at 1000 µM. In addition, these drugs are bound to acetylcholinesterase via competitive manner. Molecular modeling predicted good fitness in acetylcholinesterase active site for these drugs and possible central nervous system action for trimebutine. All of these results demonstrated that trimebutine was determined to be the drug with the highest potential for use in AD.

Effects of fentanyl and the adulterant levamisole on the rewarding and locomotor effects of methamphetamine in rats

BACKGROUND

People who use psychostimulant substances can be exposed to unknown adulterants, such as the synthetic opioid fentanyl (FEN) and the anthelmintic cholinergic agent levamisole (LEV). This work explores the rewarding and locomotor effects of methamphetamine (METH) in combination with FEN or LEV.

METHODS

We used adult male Wistar rats in the conditioned-place preference (CPP) paradigm (conditioning, extinction, and reinstatement phases) and in the open field test to study effective doses of METH, FEN, or LEV, or ineffective doses of METH+FEN or METH+LEV in combination.

RESULTS

METH and LEV, at 1mg/kg METH each, and 30µg/kg FEN produced CPP. Extinction to METH- or LEV-induced CPP occurred after eight saline injections, but it took 8-26 sessions to extinguish FEN-induced CPP. A challenge dose of 0.5mg/kg METH reinstated CPP. The same occurred with 15µg/kg FEN but not with 0.5 or 1mg/kg LEV. Training animals with ineffective doses of METH (0.01mg/kg) combined with either FEN (0.3µg/kg) or LEV (0.01mg/kg) produced CPP. Sub-effective doses of METH or FEN alone did not induce reinstatement after extinction. However, animals challenged with LEV, METH+FEN, or METH+LEV mixtures did it. Combining FEN (3µg/kg) with 0.1mg/kg METH increased locomotor activity.

CONCLUSION

Ineffective FEN and LEV doses mixed with METH produce effects larger than would be expected based on the effects of either drug alone. This outcome suggests a supra-additive interaction, which could increase the risk of developing a METH use disorder.

NETosis Secondary to the Use of Levamisole-Adulterated Cocaine: A Likely Underlying Mechanism of Vasculopathy

Background

Since 2010, several cases of a new vasculopathy induced by the use of levamisole-adulterated cocaine (LAC) have been reported. This vasculopathy is characterized by retiform purpura, earlobe necrosis, multisystem compromise, and multiple autoantibodies. Given its similarity to antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, LAC-associated vasculopathy is postulated to be mediated by pathophysiologic processes resulting from neutrophil cell death by NETosis, a phenomenon previously described in ANCA vasculitis. This study tries to establish the presence of NETosis induced by cocaine, levamisole, or both. Methodology. Neutrophils were isolated from the peripheral blood of healthy controls by Ficoll-Hystopaque density gradient centrifugation followed by dextran sedimentation. Cell viability and purity were evaluated by flow cytometry after staining with PI/DiOC6 and labeling with fluorescent anti-CD45/anti-CD3 monoclonal antibodies (mAbs), respectively. Neutrophils were exposed to levamisole, cocaine, a cocaine-levamisole mixture, and sera pools from healthy controls and patients with LAC-associated vasculopathy. NETosis was then assessed by flow cytometry after staining cells with Sytox Green, Hoechst-33342, and fluorescent antineutrophil elastase (NE) and antimyeloperoxidase (MPO) mAbs. In addition, NETosis was morphologically confirmed by fluorescence microscopy. Proinflammatory cytokine levels in culture supernatants and reactive oxygen species (ROS) synthesis were determined by flow cytometry. The involvement of calcium and muscarinic receptors in cell death induction was evaluated in parallel experiments carried out in the presence of 1,2-bis (o-aminophenoxy) ethane-N, N, N', N'-tetraacetic acid (BAPTA) and hyoscine butylbromide (HBB), their respective inhibitors.

Results

Cocaine, levamisole, and a cocaine-levamisole mixture induced neutrophil cell death. DNA/MPO extrusion and cell morphology patterns were consistent with NETosis. Neither proinflammatory cytokines nor ROS behaved as proNETotic factors. Preliminary results suggested that muscarinic receptors and calcium-dependent signals were involved in LAC-induced NETosis.

Conclusions

Cocaine, levamisole, and a cocaine-levamisole mixture can induce NETosis through mechanisms involving muscarinic receptors and calcium-dependent pathways.

Irgafos 168 and Irganox 1076 as new cocaine cutting agents: A COVID-19 pandemic impact on cocaine profiling and trafficking in Brazil

BACKGROUNDS

Restrictions in movement and closure of borders imposed by the Sars-Cov- 2 worldwide pandemic have affected the global illicit drug market, including cocaine trafficking. In this scenario, comparing cutting agents added to the cocaine and the drug purity are valuable strategies to understand how the drug trade has been impacted by the pandemic.

METHODS

In this work, 204 cocaine salt materials seized in the Brazilian Federal District, before (2019) and during COVID-19 pandemics (2020) were analyzed by two analytical techniques: gas chromatography-mass spectrometry (GC-MS) and Fourier-transform infrared spectroscopy (FTIR). Statistical analyses, including Principal Component Analysis (PCA), were applied to evaluate the COVID-19 pandemic impact in the local market. Bibliometric analysis was performed as a forensic intelligence tool.

RESULTS

From 2019-2020, cocaine average purity decreased 26 % while the frequency of cutting agents, as caffeine and anesthetics (lidocaine, tetracaine) increased. The high percentage of unknown were increased. Different cocaine profiling seized in 2020 showed new cutting agents, such as Irganox 1076, and Irgafos 168, indicating a trend on new adulterants/diluents introduced in the local market to mitigate the local drug shortage. Also in 2020, there was an increase in the local cocaine seizures, despite of the cocaine drug purity decreased by 26 % compared to 2019.

CONCLUSIONS

Taken together, these data showed that the covid-19 pandemics has impacted cocaine trafficking in the Brazilian Federal District, an increase in cocaine seizures, which may indicate greater demand for the drug and, specially, changes in the cocaine purity and cutting agents profiling showing how traffickers tried to minimize difficulties in crossing the Brazilian border during COVID-19 restrictions. The information is relevant since Brazil is one of the major departure points for traded cocaine to the world. Bibliometric analysis showed that Irgafos 168 and Irganox 1076 were consistently identified as cocaine cutting agents for the first time.

Development and validation of an automated microfluidic perfusion platform for parallelized screening of compounds in vitro

Monoamine transporters are of great interest for their role in the physiological activity of the body and their link to mental and behavioural disorders. Currently, static well-plate assays or manual perfusion systems are used to characterize the interaction of psychostimulants, antidepressants and drugs of abuse with the transporters but still suffer from significant drawbacks caused by lack of automation, for example, low reproducibility, non-comparability of results. An automated microfluidic platform was developed to address the need for more standardized procedures for cell-based assays. An automated system was used to control and drive the simultaneous perfusion of 12 channels on a microfluidic chip, establishing a more standardized protocol to perform release assays to study monoamine transporter-mediated substrate efflux. D-Amphetamine, GBR12909 (norepinephrine transporter) and p-chloroamphetamine, paroxetine (serotonin transporter) were used as control compounds to validate the system. The platform was able to produce the expected releasing (D-Amphetamine, p-chloroamphetamine) or inhibiting (GBR12909, paroxetine) profiles for the two transporters. The reduction of manual operation and introduction of automated flow control enabled the implementation of stronger standardized protocols and the possibility of obtaining higher throughput by increasing parallelization.

[Cocaine-induced vasculitis and mimics of vasculitis]

Cocaine is a psychotropic tropane alkaloid and stimulant drug. Nasal insufflation of cocaine powder is a common route of administration. In Germany, cocaine is frequently adulterated with levamisole, an anthelminthic drug with immunomodulatory effects. Both substances are linked to various autoimmune conditions. Cocaine-induced midline destructive lesions cause a progressive destruction of osteocartilaginous structures within the upper respiratory tract and can mimic localized granulomatosis with polyangiitis. In addition, systemic vasculitis due to cocaine and levamisole has been reported. Differentiation of these conditions from primary vasculitis can be challenging because antineutrophil cytoplasmic antibodies (ANCA) are commonly detected. Early diagnosis of these conditions is crucial as clinical improvement is closely related to drug cessation.

Applications and Potential of In Silico Approaches for Psychedelic Chemistry

Molecular-level investigations of the Central Nervous System have been revolutionized by the development of computational methods, computing power, and capacity advances. These techniques have enabled researchers to analyze large amounts of data from various sources, including genomics, in vivo, and in vitro drug tests. In this review, we explore how computational methods and informatics have contributed to our understanding of mental health disorders and the development of novel drugs for neurological diseases, with a special focus on the emerging field of psychedelics. In addition, the use of state-of-the-art computational methods to predict the potential of drug compounds and bioinformatic tools to integrate disparate data sources to create predictive models is also discussed. Furthermore, the challenges associated with these methods, such as the need for large datasets and the diversity of in vitro data, are explored. Overall, this review highlights the immense potential of computational methods and informatics in Central Nervous System research and underscores the need for continued development and refinement of these techniques and more inclusion of Quantitative Structure-Activity Relationships (QSARs).

Synthesis and characterization of d5 -barbarin for use in barbarin-related research

Based on structural similarities and equine administration experiments, Barbarin, 5-phenyl-2-oxazolidinethione from Brassicaceae plants, is a possible source of equine urinary identifications of aminorex, (R,S)-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine, an amphetamine-related US Drug Enforcement Administration (DEA) controlled substance considered illegal in sport horses. We now report the synthesis and certification of d₅ -barbarin to facilitate research on the relationship between plant barbarin and such aminorex identifications. D₅ -barbarin synthesis commenced with production of d₅ -2-oxo-2-phenylacetaldehyde oxime (d₅ -oxime) from d₅ -acetophenone via butylnitrite in an ethoxide/ethanol solution. This d₅ -oxime was then reduced with lithium aluminum hydride (LiAlH₄ ) to produce the corresponding d₅ -2-amino-1-phenylethan-1-ol (d₅ -phenylethanolamine). Final ring closure of the d₅ -phenylethanolamine was performed by the addition of carbon disulfide (CS₂ ) with pyridine. The reaction product was purified by recrystallization and presented as a stable white crystalline powder. Proton NMR spectroscopy revealed a triplet at 5.88 ppm for one proton, a double doublet at 3.71 ppm for one proton, and double doublet at 4.11 ppm for one proton, confirming d₅ -barbarin as the product. Further characterization by high resolution mass spectrometry supports the successful synthesis of d₅ -barbarin. Purity of the recrystallized product was ascertained by High Performance Liquid Chromatography (HPLC) to be greater than 98%. Together, we have developed the synthesis and full characterization of d₅ -barbarin for use as an internal standard in barbarin-related and equine forensic research.

Levamisole-induced and COVID-19-induced retiform purpura: two overlapping, emerging clinical syndromes

Levamisole exposure in cocaine users is a well-recognized cause of retiform purpura, a distinctive net-like maculopapular patch. Prolonged exposure to levamisole can lead to a serious systemic syndrome known as levamisole-induced vasculitis, most commonly involving the kidneys and lungs. More recently, retiform purpura has been observed in patients with the novel coronavirus disease of 2019 (COVID-19). Due to their overlapping dermatologic and systemic manifestations, levamisole-induced and COVID-19-induced retiform purpura may mimic one another in clinical presentation. The possibility that patients may present with one or both syndromes creates a diagnostic challenge. This review of levamisole-induced and COVID-19-induced retiform purpura highlights their corresponding and distinctive features. Additionally, we propose a unique staging system for levamisole-induced retiform purpura that may be valid for future classification of COVID-19-induced retiform purpura.

Characterization of Three Novel 4-Methylaminorex Derivatives Applied as Designer Drugs

The ongoing development of more and more new psychoactive substances continues to be a huge problem in 2022 affecting the European and international drug market. Through slight alterations in the structure of illicit drugs, a way to circumvent the law is created, as the created derivatives serve as legal alternatives with similar effects. A common way of structure modification is the induction of a halogen residue. Recently, halogenated derivatives of the well-known designer drug 4-methylaminorex appeared on the market and are available in various online shops. In this study, three novel halogenated 4-methylaminorex derivatives, namely 4′-fluoro-4-methylaminorex, 4′-chloro-4-methylaminorex, and 4′-bromo-4-methylaminorex, were purchased online and characterized using nuclear magnetic resonance (NMR) spectroscopy, liquid chromatography-high-resolution mass spectrometry (LC-HRMS), and chiral high-performance liquid chromatography with ultraviolet detection (HPLC-UV). These derivatives possess two stereogenic centers, and analyses revealed that all of them were present as a racemic mixture of the trans diastereomeric form.

Double Suicide Due to the Ingestion of Levamisole-Adulterated Cocaine: Case Report and Review of the Literature

Suicide is a major public health issue and the risk of attempting and committing suicide increases with age. We present the case of an elderly couple who decided to commit suicide together by self-poisoning using levamisole-adulterated cocaine. The choice of committing a double suicide, the method selected (self-poisoning), the drug self-administered (cocaine), and the route of administration (ingestion) are events rarely encountered in the forensic pathology practice, especially not in combination. In this article, we will review the literature regarding the frequency and features of these methods of suicide. An overview of the effects and mechanism of action of levamisole is also provided, highlighting the importance of including this substance and its metabolites in the routine toxicological analyses for cocaine deaths.

Cocaine and Levamisole Induced Vasculitis

Levamisole adulterated cocaine is a rare cause of anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis. It is increasingly diagnosed because of raised awareness; however, it is still underdiagnosed in part because of its rarity and patients not reporting cocaine use. Here we report a case of levamisole-induced vasculitis. We present a 48-year-old non-Hispanic white male with a past medical history significant for Crohn’s Disease and pneumonia who presented with acute bilateral ear pain and rash. His urinary drug screen was positive, which prompted suspicion of contamination and potential levamisole adulterated cocaine-associated vasculitis. A punch biopsy showed evidence of leukocytoclastic vasculitis and multiple fibrin thrombi further supporting contamination with levamisole. We believe this case highlights the importance of using patient history in guiding diagnostic testing in the setting of acute vasculitis. Once the history of illicit substance use was confirmed, our differential diagnosis and considerations for treatment significantly changed. 

Levamisole, a cocaine cutting agent, induces acute and subchronic systemic alterations in Wistar rats

The use of the anthelmintic levamisole as a cocaine adulterant has been increasing worldwide. Complications caused by this association include systemic vasculitis, agranulocytosis, neutropenia, tissue necrosis, pulmonary hemorrhage, and renal injury. Data about toxicity of levamisole are scarce, therefore the aim of this study was to evaluate the acute and subchronic toxic effects of levamisole in rats. Male Wistar rats received saline or levamisole by intraperitoneal route at the doses of 12, 24 and 36 mg/kg in the acute toxicity test; and at 3, 6 and 12 mg/kg in the subchronic toxicity test. Toxicity was evaluated using behavioral, cognitive, renal, hematological, biochemical and histopathological parameters. Acute administration of levamisole caused behavioral and histopathological alterations. Subchronic administration caused behavioral, cognitive and hematological alterations (p < 0.0001 and p < 0.05, respectively), impairment of liver and kidney functions (p < 0.05), and changes of antioxidant defenses (p ≤ 0.0001). Both administrations produced toxic effects of clinical relevance, which make levamisole a dangerous cutting agent. Furthermore, the knowledge of these effects can contribute to the correct diagnosis and treatment of cocaine dependents with unusual systemic alterations.

Cutting agents in cocaine: A temporal study of the period 2015-2017 in the Northern Region of Colombia

Cocaine is a naturally occurring psychostimulant drug available worldwide. Drug trafficking networks adulterate pure cocaine with cutting agents to increase their earnings. This study presents a descriptive statistical analysis of the cutting agents found in 2118 cocaine samples that were seized in the Northern Region of Colombia (in the period 2015-2017). The data used in this study was drawn from the GC-MS analytical reports of the National Institute of Legal Medicine and Forensic Sciences -Colombia, Northern Region. Results showed diverse cutting agents in seized cocaine samples, from which the most commonly used are caffeine, phenacetin, lidocaine, imidazole and levamisole. In addition, cocaine samples showed different mixtures of the above cutting agents, predominantly caffeine/phenacetin and caffeine/lidocaine/phenacetin mixtures.

Inherent Dangers of Using Non-US Food and Drug Administration-Approved Substances of Abuse

Use of US Food and Drug Administration-approved substances of abuse has innate risks due to pharmacologic and pharmacokinetic properties of the medications, but the risk when using nonapproved drug products is much greater. Unbeknownst to the user, the dose of active ingredients in substances of abuse can vary substantially between different products because of manufacturing practices or improper storage. Even naturally occurring substances of abuse can have extensive dosage variability because of effects of the growing season and conditions, or differences in harvesting, storage, or manufacture of the finished products. Many illicit substances are adulterated, to make up for intentional underdosing or to enhance the effect of the intended active ingredient. These adulterants can be dangerous and produce direct cardiovascular, neurologic, hematologic, or dermatologic reactions or obscure adverse effects. Finally, an illicit substance can be contaminated or substituted for another one during its manufacture, leading to differences in adverse events, adverse event severity, or the drug interaction profile. Substances can be contaminated with microbes that induce infections or heavy metals that can damage organs or cause cancer. This milieu of undisclosed substances can also induce drug interactions. For reasons that are discussed, individuals who use substances of abuse are at increased risk of morbidity or mortality if they develop coronavirus disease 2019. Health professionals who treat patients with acute, urgent events associated with substances of abuse, or those treating the chronic manifestations of addiction, need to appreciate the complex and variable composition of substances of abuse and their potential health effects.

Adverse reactions with levamisole vary according to its indications and misuse: a systematic pharmacovigilance study

AIM

Levamisole was initially prescribed for the treatment of intestinal worms. Because of immunomodulatory properties, levamisole has been used in inflammatory pathologies and in cancers in association with 5-fluorouracil. Levamisole is misused as a cocaine adulterant. Post-marketing reports have implicated levamisole in the occurrence of adverse drug reactions (ADRs) and its use is now limited in Europe and North America. In contrast, all other parts of the World continue to use single-dose as an anthelmintic. The aim of this study was to identify ADRs reported after levamisole exposure in VigiBase, the WHO's pharmacovigilance database, and analyze their frequency compared to other drugs and according to levamisole type of use.

METHODS

All levamisole-related ADRs were extracted from VigiBase®. Disproportionality analyses were conducted to investigate psychiatric, hepatobiliary, renal, vascular, nervous, blood, skin, cardiac, musculoskeletal and general ADRs associated with levamisole and other drugs exposure. In secondary analyses, we compared the frequency of ADRs between levamisole and mebendazole and between levamisole type of use.

RESULTS

Among the 1763 levamisole-related ADRs identified, psychiatric disorders (Reporting Odds-Ratio with 95% confidence intervals: 1.4 [1.2-2.6]), hepatobiliary disorders (2.4 [1.9-4.3]), vasculitis (6.5 [4.1-10.6]), encephalopathy (22.5 [17.4-39.9]), neuropathy (4.3 [2.9-7.1]), hematological disorders, mild rashes and musculoskeletal disorders were more frequently reported with levamisole than with other drug. The majority of levamisole-related ADRs occurred when the drug was administrated for a non-anti-infectious indication.

CONCLUSION

The great majority of the levamisole-related ADRs concerned its immunomodulatory indication and multiple doses regimen. Our results suggest that single-dose treatments for anthelmintic action have a good safety profile.

An Overview of Cell-Based Assay Platforms for the Solute Carrier Family of Transporters

The solute carrier (SLC) superfamily represents the biggest family of transporters with important roles in health and disease. Despite being attractive and druggable targets, the majority of SLCs remains understudied. One major hurdle in research on SLCs is the lack of tools, such as cell-based assays to investigate their biological role and for drug discovery. Another challenge is the disperse and anecdotal information on assay strategies that are suitable for SLCs. This review provides a comprehensive overview of state-of-the-art cellular assay technologies for SLC research and discusses relevant SLC characteristics enabling the choice of an optimal assay technology. The Innovative Medicines Initiative consortium RESOLUTE intends to accelerate research on SLCs by providing the scientific community with high-quality reagents, assay technologies and data sets, and to ultimately unlock SLCs for drug discovery.

Use of levamisole-adulterated cocaine is associated with increased load of white matter lesions

Background

Cocaine use has been associated with vascular pathologies, including cerebral white matter hyperintensities. Street cocaine is most often adulterated with levamisole, an anthelminthic drug that may also be associated with vascular toxicity. However, whether levamisole exposure from cocaine consumption further accelerates the development of white matter lesions remains unknown.

Methods

We investigated the association of cocaine and levamisole exposure with white matter hyperintensities in 35 chronic cocaine users and 34 healthy controls. We measured cocaine and levamisole concentrations in hair samples, which reflected exposure up to 6 months previously. We assessed the number and total surface area of the white matter hyperintensities using structural MRI (FLAIR sequence). Using generalized linear models, we analyzed the contributions of cocaine and levamisole to the number and area of white matter hyperintensities, accounting for several confounding factors.

Results

Analysis using generalized linear models revealed that cocaine users had more white matter hyperintensities in terms of total surface area, but not in terms of number. Further generalized linear models that included cocaine and levamisole hair concentrations (instead of group) as predictors indicated that levamisole exposure was strongly associated with more and larger white matter hyperintensities, suggesting that the elevated white matter hyperintensities in cocaine users were driven mainly by levamisole exposure. Finally, white matter hyperintensities in levamisole-exposed cocaine users were located primarily in the periventricular and juxtacortical white matter.

Limitations

The sample size was moderate, and blood pressure was not systematically assessed.

Conclusion

As an adulterant of cocaine, levamisole appears to increase the risk of white matter injury.

Levamisole-a Toxic Adulterant in Illicit Drug Preparations: a Review

ABSTRACT

Discovered in the 1960s, the common anthelminthic levamisole has seen widespread use in veterinary applications. Its use rapidly expanded thereafter to include human medical treatments for a variety of acute and chronic disorders. Because of reports of severe adverse effects, the US Food and Drug Administration withdrew levamisole's approval for human use in 2000; however, medical options outside the United States and illicit options worldwide allow continued accessibility to levamisole. The compound is rapidly metabolized in the body, with at least 2 known active metabolites. Levamisole has a broad range of immunomodulatory effects, including both stimulatory and inhibitory effects on immune responses. It is generally well tolerated at therapeutic concentrations, although a variety of autoimmune-related adverse effects have been reported, including agranulocytosis, leukopenia, purpura, and visible necrotized skin tissue. Individuals with levamisole-compromised immune systems are more susceptible to infections, including COVID-19. Since the early 2000's, levamisole has been frequently used as an adulterating agent in illicit street drugs, especially cocaine, fentanyl, and heroin. Although its prevalence has varied over time and geographically, levamisole has been detected in up to 79% of the street supply of cocaine at levels up to 74% by weight. Its presence in illicit drug markets also raises concern over the potential for exposure of children and neonates, although this is supported by only limited anecdotal evidence. Levamisole is not currently included in routine drug testing panels, although a variety of confirmatory testing techniques exist across a range of antemortem and postmortem specimen options. Because of its varying presence in illicit drug markets, both the medical and forensic communities need to be aware of levamisole and its potential impact on toxicological investigations.

Cerebral vasculitis associated with drug abuse

PURPOSE OF REVIEW

To review understand the epidemiology, background, neuropharmacology, and histopathology of literature verified cases, and likely etiopathogenic mechanisms.

RECENT FINDINGS

There are only a handful of histologically confirmed patients in the literature with cerebral vasculitis because of drug abuse.

SUMMARY

There is little justification for invasive laboratory investigation given the ready availability of highly accurate vascular neuroimaging techniques to dictate management, which usually rests upon avoidance of further exposure and minimizing the secondary neurotoxic effects of the abused substances and polypharmacy use.

A fatal case after an intravenous injection of levamisole

Levamisole is a drug originally prescribed as an antihelmintic. Because of the occurrence of severe cases of agranulocytosis and leukoencephalitis it was removed from the French market in 1998 for human use, while it remains available for veterinary use. Nowadays in France its only use in humans is regulated by authorization for temporary use for its immunomodulatory properties in the treatment of nephritic syndrome.A 52-year-old man was found dead at his farm. Injection points were observed on his arm and a syringe containing a dark orange-brown liquid was found near the body. At his home, the discovery of a letter highlighted suicidal intent. Analysis of the aforementioned liquid, peripheral blood and urine confirmed the unique presence of levamisole. The femoral blood concentration of levamisole was of 25 mg/L whereas the femoral blood concentrations reported in cases of fatalities after cocaine use do not exceed 0.0056 mg/L. In humans, levamisole can be detected in biological samples after cocaine use as this drug is also an adulterant and one of its metabolites (aminorex) seems to have amphetamine-like properties. In this case, the man consumed levamisole from time to time for its stimulant and strengthening effects.Cases of fatal poisoning using levamisole are very rare and poorly documented, which makes the interpretation of postmortem blood levamisole concentration difficult.

[Multifocal inflammatory levamisole-induced leukoencephalopathy]

Levamisole (L) is an anthelmintic agent that is widely used in clinical practice. L can enter the human organism during the treatment of helminthiasis as well as during the using the contaminated cocaine. Multifocal inflammatory levamisole-induced leukoencephalopathy (MILL) is one of the most serious complications of L use. The article discusses the clinical and radiological features of MILL which have a number of similarities of multiple sclerosis (MS) appearance. The disease has a favorable prognosis if started early, but the diagnosis of this rare form of leukoencephalopathy can cause difficulties. The case of MILL in patient with mistaken diagnosis of MS is descrThe case of MILL in patient with mistaken diagnosis of MS is descraibed.ibed.

Synthesis and characterization of barbarin, a possible source of unexplained aminorex identifications in forensic science

Aminorex is a US DEA Schedule 1 controlled substance occasionally detected in racing horses. A number of aminorex identifications in sport horses were thought to have been caused by exposure to plant sources of aminorex. Glucobarbarin, found in plants of the Brassicaceae family, has been suggested as a potential proximate chemical source by being metabolized in the plant or the horse to aminorex. In Brassicaceae, glucobarbarin is hydrolyzed by myrosinase to yield barbarin, which serves as an insect repellant and/or attractant and is structurally related to aminorex. The synthesis, purification, and characterization of barbarin is now reported for use as a reference standard in aminorex related research concerning equine urinary identifications of aminorex and also for possible use in equine administration experiments. Synthesis of barbarin was performed via ring closure between phenylethanolamine and carbon disulfide in tetrahydrofuran with the catalyst pyridine under reflux. The reaction yielded a white crystalline substance that was purified and chemically characterized as barbarin for use as a Certified Reference Standard or for studies related to equine aminorex identification.

The Amino Terminus of LeuT Changes Conformation in an Environment Sensitive Manner

Neurotransmitter:sodium symporters are highly expressed in the human brain and catalyze the uptake of substrate through the plasma membrane by using the electrochemical gradient of sodium as the energy source. The bacterial homolog LeuT, a small amino acid transporter isolated from the bacteria Aquifex aeolicus, is the founding member of the family and has been crystallized in three conformations. The N-terminus is structurally well defined and strongly interacts with the transporter core in the outward-facing conformations. However, it could not be resolved in the inward-facing conformation, which indicates enhanced mobility. Here we investigate conformations and dynamics of the N-terminus, by combining molecular dynamics simulations with experimental verification using distance measurements and accessibility studies. We found strongly increased dynamics of the N-terminus, but also that helix TM1A is subject to enhanced mobility. TM1A moves towards the transporter core in the membrane environment, reaching a conformation that is closer to the structure of LeuT with wild type sequence, indicating that the mutation introduced to create the inward-facing structure might have altered the position of helix TM1A. The mobile N-terminus avoids entering the open vestibule of the inward-facing state, as accessibility studies do not show any reduction of quenching by iodide of a fluorophore attached to the N-terminus.

Effects of cocaine and levamisole (as adulterant) on the isolated perfused Langendorff heart

Cocaine-related deaths occur regularly in forensic routine work. In cases in which the detected concentration of cocaine is rather low and other causes of death apart from intoxication can be ruled out, the question arises if adulterants of cocaine might have played a crucial role. In the present study, cardiac effects of cocaine, of the adulterant levamisole and of mixtures of both were evaluated using the isolated perfused Langendorff heart. While exposed to the substances, functional parameters heart rate, left ventricular pressure and coronary flow were documented. Relevant alterations of these parameters were found for cocaine as well as for levamisole. Exposing the hearts to a mixture of both resulted in a combination of these effects; the emergence of new alterations or an obvious aggravation were not detected. Nevertheless, the results imply that the consumption of cocaine adulterated with levamisole bares an increased risk for cardiac complications, especially in the presence of preexisting cardiac pathologies.

Role of the Aryl Hydrocarbon Receptor/ARNT/Cytochrome P450 System in Pulmonary Vascular Diseases

RATIONALE

CYPs (cytochrome p450) are critically involved in the metabolism of xenobiotics and toxins. Given that pulmonary hypertension is strongly associated with environmental exposure, we hypothesize that CYPs play a role in the development and maintenance of pathological vascular remodeling.

OBJECTIVE

We sought to identify key CYPs that could link drug or hormone metabolism to the development of pulmonary hypertension.

METHODS AND RESULTS

We searched in Medline (PubMed) database, as well as http://www.clinicaltrials.gov, for CYPs associated with many key aspects of pulmonary arterial hypertension including, but not limited to, severe pulmonary hypertension, estrogen metabolism, inflammation mechanisms, quasi-malignant cell growth, drug susceptibility, and metabolism of the pulmonary arterial hypertension-specific drugs.

CONCLUSIONS

We postulate a hypothesis where the AhR (aryl hydrocarbon receptor) mediates aberrant cell growth via expression of different CYPs associated with estrogen metabolism and inflammation.

Adulterants in crack cocaine in Brazil

Abstract Introduction Brazil is the world’s biggest consumer of crack cocaine, and dependence is a major public health issue. This is the first study to investigate the prevalence of potentially harmful adulterants present in hair samples from Brazilian patients with crack cocaine dependence. Method We evaluated adulterants in hair samples extracted by convenience from 100 patients admitted at the 48 hour-observation unit of Centro de Referência de Álcool, Tabaco e Outras Drogas (CRATOD), Brazil’s largest center for addiction treatment. A cross-sectional analysis was performed with the data obtained. Results Adulterants were found in 97% of the analyzed hair samples. The most prevalent adulterant was lidocaine (92%), followed by phenacetin (69%) and levamisole (31%). Conclusion Adulterants were widely prevalent in hair samples from crack users treated at CRATOD: at least one adulterant was present in virtually all the hair samples collected. This points to a need to monitor adverse effects in the clinical setting in order to provide this high-risk group of patients with prompt and effective care related to the acute and chronic complications associated with these adulterants.

Central Nervous System Vasculitis Due to Substance Abuse

Illicit drug abuse is a common differential diagnosis of acquired central nervous system vasculitis even though there are only a handful of histopathologically confirmed patients in the literature from among the many potential classes of abused drugs traditionally implicated in this disease. This article considers the major classes of illicit drugs in those with and without human immunodeficiency virus type-1 infection and acquired immune deficiency syndrome.

The synthetic cathinones, butylone and pentylone, are stimulants that act as dopamine transporter blockers but 5-HT transporter substrates

RATIONALE

Synthetic cathinones continue to emerge in recreational drug markets worldwide. 1-(1,3-Benzodioxol-5-yl)-2-(methylamino)butan-1-one (butylone) and 1-(1,3-benzodioxol-5-yl)-2-(methylamino)pentan-1-one (pentylone) are derivatives of the cathinone compound, 1-(1,3-benzodioxol-5-yl)-2-(methylamino)propan-1-one (methylone), that are being detected in drug products and human casework.

OBJECTIVES

The purpose of the present study was to examine the neuropharmacology of butylone and pentylone using in vitro and in vivo methods.

METHODS

In vitro uptake and release assays were carried out in rat brain synaptosomes and in cells expressing human dopamine transporters (DAT) and 5-HT transporters (SERT). In vivo microdialysis was performed in the nucleus accumbens of conscious rats to assess drug-induced changes in neurochemistry.

RESULTS

Butylone and pentylone were efficacious uptake blockers at DAT and SERT, though pentylone was more DAT-selective. Both drugs acted as transporter substrates that evoked release of [³H]5-HT at SERT, while neither evoked release at DAT. Consistent with the release data, butylone and pentylone induced substrate-associated inward currents at SERT but not DAT. Administration of butylone or pentylone to rats (1 and 3 mg/kg, i.v.) increased extracellular monoamines and motor activity, but pentylone had weaker effects on 5-HT and stronger effects on motor stimulation.

CONCLUSIONS

Our data demonstrate that increasing the α-carbon chain length of methylone creates "hybrid" transporter compounds which act as DAT blockers but SERT substrates. Nevertheless, butylone and pentylone elevate extracellular dopamine and stimulate motor activity, suggesting both drugs possess significant risk for abuse.

Cognitive and neuroanatomical impairments associated with chronic exposure to levamisole-contaminated cocaine

Currently, levamisole is the most common cocaine adulterant worldwide and it is known to induce a variety of adverse side effects. Animal studies and human case reports suggest potential neurotoxicity of the compound but neither neuroanatomical nor cognitive effects of levamisole have been systematically investigated in cocaine users so far. We examined cognitive performance and cortical structural differences between chronic cocaine users with low and high recent exposure to levamisole objectively determined by quantitative toxicological hair analyses. In Study 1, we compared 26 chronic cocaine users with low levamisole exposure (lowLevCU), 49 matched cocaine users with high levamisole exposure (highLevCU), and 78 matched stimulant-naive controls regarding cognitive functioning employing a comprehensive neuropsychological test battery. In Study 2, we investigated cortical thickness by use of T1-weighted MRI in a subgroup of 12 lowLevCU, 17 highLevCU, and 38 stimulant-naive controls. In Study 1, both cocaine user groups showed significant impairments in the cognitive domains of attention and working memory as well as in the global cognitive index. However, highLevCU showed significantly worse executive functions compared to lowLevCU although both groups did not differ in severity of cocaine consumption and other clinical dimensions. Study 2 revealed that highLevCU, displayed reduced cortical thickness specifically in the middle frontal gyrus compared to both controls and lowLevCU. Our results suggest that levamisole exposure during the last months in cocaine users is associated with increased executive function impairments and pronounced thinning of the lateral prefrontal cortex. Consequently, prevention and drug policy-making should aim to reduce levamisole contamination of street cocaine.

DARK Classics in Chemical Neuroscience: Aminorex Analogues

Aminorex (5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) and 4-methylaminorex (4-methyl-5-phenyl-4,5-dihydro-1,3-oxazol-2-amine) are psychostimulants that have long been listed in Schedules IV and I of the UN Convention on Psychotropic Substances of 1971. However, a range of psychoactive analogues exist that are not internationally controlled and therefore often classified as new psychoactive substances (NPS). Aminorex analogues encompass failed pharmaceuticals that reemerged as drugs of abuse, and newly synthesized substances that were solely designed for recreational use by clandestine chemists. NPS, sometimes also referred to as "designer drugs" in alignment with a phenomenon arising in the early 1980s, serve as alternatives to controlled drugs. Aminorex and its derivatives interact with monoaminergic neurotransmission by interfering with the function of monoamine transporters. Hence, these compounds share pharmacological and neurochemical similarities with amphetamines and cocaine. The consumption of aminorex, 4-methylaminorex and 4,4'-dimethylaminorex (4-methyl-5-(4-methylphenyl)-4,5-dihydro-1,3-oxazol-2-amine) has been associated with adverse events including death, bestowing an inglorious fame on aminorex-derived drugs. In this Review, a historical background is presented, as well as an account of the pharmacodynamic and pharmacokinetic properties of aminorex and various analogues. Light is shed on their misuse as drug adulterants of well-established drugs on the market. This Review not only provides a detailed overview of an abused substance-class, but also emphasizes the darkest aspect of the NPS market, i.e., deleterious side effects that arise from the ingestion of certain NPS, as knowledge of the pharmacology, the potency, or the identity of the active ingredients remains obscure to NPS users.

Levamisole-Adulterated Cocaine Leading to Fatal Vasculitis: A Case Report

Cocaine is often "cut" with various additives to increase the profitability of the drug. One of the most common additives on today's market is levamisole, an anthelmintic medication used to destroy and expel parasitic worms in animals. The use of levamisole-contaminated cocaine can result in agranulocytosis and vasculitis (inflammation and constriction of small blood vessels). The resulting clotting and decrease in peripheral blood flow lead to cutaneous lesions, particularly on the ears, face, hands, and feet, and in severe cases can cause generalized tissue necrosis throughout the entire body. Treatment is generally supportive, and symptoms typically abate with complete cessation of cocaine use. However, symptoms may recur with subsequent cocaine use and, as this case illustrates, severe neutropenia and extensive vasculitis may lead to overwhelming sepsis and death.

Unusual case of levamisole-induced dual-positive ANCA vasculitis and crescentic glomerulonephritis

Cocaine adulterated levamisole is an increasingly reported cause of skin necrosis, arthralgia and systemic vasculitis, but renal involvement is uncommon. We present a case of a 40-year-old Hispanic man with a history of cocaine abuse who presented with acute kidney injury to the rheumatology clinic where he was being treated for chronic inflammatory arthritis. He was found to have a serum creatinine of 2.5 mg/dL, microscopic haematuria and subnephrotic proteinuria, along with positive proteinase 3, myeloperoxidase, anticardiolipin antibodies and an elevated antinuclear antibody titre. The renal pathology revealed focal necrotising glomerulonephritis with crescentic features and mild immune type deposition. The patient was treated with cocaine abstinence, pulse dose steroids followed by maintenance prednisone, rituximab and cyclophosphamide. His renal function subsequently improved but did not normalise. We believe that his incomplete improvement was due to the degree of kidney injury on presentation as well as recidivism with cocaine use.

Levamisole-induced vasculopathy: A systematic review

OBJECTIVE

To characterize levamisole-induced vasculopathy.

METHODS

We performed a systematic review searching MEDLINE for articles published from 1972 to 2016.

RESULTS

We retrieved 357 references and abstracts and selected 111 articles. Levamisole-induced vasculopathy was reported in 192 patients, with a female predominance (n = 122, 63.5%). Median [interquartile range] age was 44 [38-50]. Skin was the most frequently involved organ (n = 182, 94.8%). Cutaneous lesions were mostly on the face (n = 136, 70.8%), especially the ears. Purpura (n = 131, 68.2%) was the most reported cutaneous lesion. Organ involvement included acute renal failure (n = 24, 12.5%), and pulmonary involvement (n = 20, 10.4%). Anti-neutrophil cytoplasmic antibodies (ANCAs) were found in 167/178 patients (93.8%), with both anti-myeloperoxydase and anti-proteinase 3 specificity reported in 51/118 patients (43.2%). Anti-phospholipid (APL) antibodies were found in 93/137 patients (67.9%). Leukopenia was detected in 69/138 patients (50%). Skin biopsies identified vasculitis and thrombotic vasculopathy in 73/148 (49.3%) and 62/148 (41.9%) patients, respectively. The outcome was favourable in 116/134 patients (86.6%), but relapses were reported in 33 (28.4%), mainly on levamisole re-exposure.

CONCLUSION

Levamisole-induced vasculopathy is characterized by a female predominance, skin involvement, ANCA and/or APL antibody positivity, leukopenia, vasculitis or vascular thrombotic histological lesions, and despite possible systemic involvement, a favourable outcome with levamisole interruption.

Discriminative stimulus effects of cocaine-levamisole combinations in Sprague-Dawley rats

BACKGROUND

Levamisole (LVM) is a common adulterant in clandestinely manufactured cocaine (COC), with a range of well-documented deleterious health effects. Although the prevalence of LVM in COC has been widely noted, the subjective effects related to concomitant COC-LVM administration are poorly understood.

AIMS

The present study sought to compare the subjective effects of LVM alone and in combination with COC in male and female Sprague-Dawley rats trained to discriminate COC from vehicle injections.

METHODS

Male and female Sprague-Dawley rats were trained to discriminate COC from vehicle injections using a two-lever, food-reinforced drug discrimination procedure. Subsequent dose-effect curves were generated for COC, LVM, and a variety of COC-LVM combinations.

RESULTS

No significant difference in males and females was observed on any measure of responding. LVM alone dose-dependently decreased response rates and failed to produce substitution for COC. When LVM was administered with COC, previously ineffective doses of COC engendered COC-appropriate responding.

CONCLUSIONS

LVM potentiates the subjective effects of COC when administered concomitantly. These findings are consistent with the popular notion that LVM is added as an adulterant to COC to amplify the subjective effects of COC administration.

Cocaine/levamisole-associated autoimmune syndrome: a disease of neutrophil-mediated autoimmunity

PURPOSE OF REVIEW

Levamisole was previously used for its immunomodulatory properties to treat rheumatoid arthritis and some cancers. However, because of serious side-effects, it was taken off the market in the United States. Recently, levamisole has reemerged as a popular cocaine adulterant. Some individuals who consume levamisole-adulterated cocaine can develop a life-threatening autoimmune syndrome. In this review, the medical consequences of levamisole exposure and postulated mechanisms by which levamisole induces these adverse effects are discussed.

RECENT FINDINGS

Although agranulocytosis and cutaneous vasculitis are the major findings in patients who develop cocaine/levamisole-associated autoimmune syndrome (CLAAS), more recent experience indicates that other organ systems can be involved as well. Current studies point to neutrophil activation and neutrophil extracellular trap formation with subsequent antineutrophil cytoplasmic antibody-mediated tissue injury as a possible mechanism of CLAAS.

SUMMARY

In the past decade, the detrimental effects of levamisole have reemerged because of its popularity as a cocaine adulterant. Although infrequent, some individuals develop a systemic autoimmune syndrome characterized by immune-mediated agranulocytosis and antineutrophil cytoplasmic antibody-mediated vasculitis. Mechanistically, neutrophil antigens appear to be a major player in inducing CLAAS. Prompt cessation of levamisole exposure is key to treatment, although relapses are frequent because of the addictive effects of cocaine and the high prevalence of levamisole within the cocaine supply.

The psychostimulant (±)-cis-4,4'-dimethylaminorex (4,4'-DMAR) interacts with human plasmalemmal and vesicular monoamine transporters

(±)-cis-4,4'-Dimethylaminorex (4,4'-DMAR) is a new psychoactive substance (NPS) that has been associated with 31 fatalities and other adverse events in Europe between June 2013 and February 2014. We used in vitro uptake inhibition and transporter release assays to determine the effects of 4,4'-DMAR on human high-affinity transporters for dopamine (DAT), norepinephrine (NET) and serotonin (SERT). In addition, we assessed its binding affinities to monoamine receptors and transporters. Furthermore, we investigated the interaction of 4,4'-DMAR with the vesicular monoamine transporter 2 (VMAT2) in rat phaeochromocytoma (PC12) cells and synaptic vesicles prepared from human striatum. 4,4'-DMAR inhibited uptake mediated by human DAT, NET or SERT, respectively in the low micromolar range (IC₅₀ values < 2 μM). Release assays identified 4,4'-DMAR as a substrate type releaser, capable of inducing transporter-mediated reverse transport via DAT, NET and SERT. Furthermore, 4,4'-DMAR inhibited both the rat and human isoforms of VMAT2 at a potency similar to 3,4-methylenedioxymethylamphetamine (MDMA). This study identified 4,4'-DMAR as a potent non-selective monoamine releasing agent. In contrast to the known effects of aminorex and 4-methylaminorex, 4,4'-DMAR exerts profound effects on human SERT. The latter finding is consistent with the idea that fatalities associated with its abuse may be linked to monoaminergic toxicity including serotonin syndrome. The activity at VMAT2 suggests that chronic abuse of 4,4'-DMAR may result in long-term neurotoxicity.

Recurrent Levamisole-Induced Agranulocytosis Complicated by Bowel Ischemia in a Cocaine User

BACKGROUND Levamisole is a common adulterant of cocaine and up to 69% of seized cocaine in United States contains levamisole. It is a synthetic imidazothiazole derivative which was previously used as an immunomodulating agent for treatment of various connective tissue disorders and colorectal carcinoma. However, it was withdrawn later from the market due to significant toxicity associated with it. CASE REPORT We present the case of a 59-year-old male patient with a history of active cocaine use who presented to the hospital with febrile neutropenia and agranulocytosis. He underwent extensive work-up for neutropenia and was suspected to have it secondary to levamisole-adulterated cocaine. He was treated with antibiotics and granulocyte-stimulating factor. His white cell count improved and he was discharged home. He continued to use cocaine after discharge from the hospital. He returned to the hospital 3 weeks later with recurrent neutropenia and agranulocytosis complicated by septic shock and bowel necrosis which required prolonged antibiotics and a bowel resection. CONCLUSIONS Levamisole-induced agranulocytosis should be considered in patients who present with neutropenia and a history of cocaine use. Physicians should have high clinical suspicion and consider it a potential etiology of agranulocytosis when other causes have been excluded.