Levamisole in Illicit Trafficking Cocaine Seized: A One-Year Study

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.

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.

Comparison of Illicit Drug Seizures Products of Natural Origin Using a Molecular Networking Approach

Drug powder composition analysis is of particular interest in forensic investigations to identify illicit substance content, cutting agents and impurities. Powder profiling is difficult to implement due to multiple analytical methods requirement and remains a challenge for forensic toxicology laboratories. Furthermore, visualization tools allowing seizure products identification appear to be under-used to date. The aim of this study is to present the utility of molecular networking for the composition establishment of natural origin drugs. A powder suspected to contain heroin and three powders suspected to contain cocaine obtained from law enforcement agency seizures were analyzed using untargeted screening by liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS/MS). Molecular networking and metabolite annotation applied to suspected heroin sample allowed rapid confirmation of its illicit content (heroin), the identification of structurally related major impurities (6-monoacetylmorphine, 6-monoacetylcodeine, noscapine, and papaverine), as well as cutting agents (acetaminophen and caffeine). The cocaine powder profiling allowed the comparison of its constituents in a semi-quantitative manner (cocaine, benzoylecgonine, trans/cis-cinnamoylcocaine, trimethoxycocaine, hexanoylecgonine methylester, caffeine, hydroxyzine, levamisole, and phenacetin), bringing additional information for their identification, including geographically sourcing of natural product and their putative place in the supply chain. Although this approach does not replace the profiling techniques used by forensic laboratories, the use of molecular networks provides a visual overview of structurally related constituents which aids the comparison and investigation of seizure powders. Molecular networks offers here an ideal way to depict structurally related and unrelated compounds in these often complex mixtures of chemicals.

Purity of street-level cocaine across Denmark from 2006 to 2019: Analysis of seized cocaine

Cocaine-related emergency department admissions are increasing, and cocaine seizures are at an all-time high in Europe. Our aim was to investigate the trends in purity and adulterants over time in cocaine available to cocaine users at street level in Denmark. We used a representative sample of cocaine seized at street level and analyzed by the national departments of forensic medicine between 2006 and 2019 (n = 1460). Latent profile analysis was used to classify the samples based on cocaine, levamisole, and phenacetin content. Low purity cocaine comprised most of the cocaine seizures in early years, but its share began to decline in 2013, and from 2016 to 2019, the high purity profile was dominant. While the total number of samples containing adulterants decreased, levamisole remained a common and dangerous adulterant. The findings underline the need to inform the public, medical doctors, and service providers for people with drug use disorders about the higher potency of street cocaine.

Personal Doses of Cocaine and Coca Paste are Adulterated in Cartagena de Indias (Colombia)

Knowledge of drug composition consumed on the streets and the identification and quantification of their adulterants is essential for understanding unexpected side effects, tracking routes, and drug profiling. Therefore, this work aimed to determine the purity and to identify and quantify the main adulterants found in personal doses of cocaine (perico) and coca paste (bazuco) in Cartagena de Indias (Colombia). The data collected in this study describe a first attempt to introduce the qualitative and quantitative analyses of adulterants present in street drugs in Cartagena de Indias to improve surveillance. Through gas chromatography coupled to mass spectrometry (GC-MS), the purity and adulterants were quantified in 45 personal doses of cocaine powder and coca paste. 100% of the personal doses in the city were adulterated; caffeine, phenacetin, and levamisole were the main adulterants identified in cocaine. Besides the above, lidocaine was also found in coca paste. The purity of cocaine varied from 8% to almost 70%, with caffeine ranging from 6% to 42%. In the case of coca paste, the maximum content of cocaine found was 60%, while some samples contained as little as 14%. The results are consistent with other research in terms of the widespread use of caffeine as an adulterant, but they also follow the growing trend of the use of levamisole and phenacetin. The wide range of cocaine content in samples sold in the illicit market could cause undesirable effects on cocaine users who do not know the exact intended dose for consumption; so, this study intends to make these results available not only to academic, public health, and national security agencies but also to tourists entering Cartagena de Indias, so that they are aware of what they are consuming and the risks to which they are exposed.

Separation and Determination of the Enantiomeric Levamisole and Dexamisole in Equine Plasma Samples Using Chiral Polysaccharide Column/ LC-MS/MS

Background:

Drug Enforcement Administration confirmed that many manufacturers began adding tetramisole or its individual isomers to cocaine as an adulterant, and believed that tetramisole may augment cocaine’s effects. In recent times, there is an increasing trend in the usage of tetramisole and its individual enantiomer in race sports especially in horse and camel races. So it’s is very much required to confirm the stereochemistry of this illicit drug in the routine race day samples coming to the anti-doping labs in order to avoid legal arguments and challenges to the analytical findings.

Methods:

The aim of the study was to develop a simple, rapid and accurate method for the chiral separation and determination of enantiomeric mixtures of levamisole and dexamisole using Thermo Q-Exactive High-Resolution Mass Spectrometer. In order to evaluate the suitability of the method for determining the enantiomeric purity of tetramisole, validation studies were also carried out by using equine plasma.

Results:

The enantio-separation was achieved using the Lux i-cellulose-5 column. Isocratic flow was used with a 1:1 mixture of mobile phase A (10 mM ammonium acetate in water) and mobile phase B (acetonitrile), at a flow rate of 0.6 mL/min. The run time was 8.0 min, and the column temperature was 50°C. Dexamisole eluted at 5.94 min, and levamisole eluted at 6.62 min, giving the R-value of 1.50. The obtained inter-day precisions of dexamisole, levamisole were 3.16% and 2.85%, respectively. The accuracy of dexamisole was in the range of 97.78 to 102.44%, and that for levamisole was 99.16 to 102.82%. The limit of quantification value for both isomers in this method was 0.1 ng/ mL. The method was linear in the range of 0 to 50 ng/mL.

Conclusion:

Chromatographic separation was achieved using the polysaccharide cellulose chiral column, and the reverse-phase separation approach was found to have the highest potential for successful chiral resolution in LC-MS. Linearity, precision, accuracy, detection limit, recovery, and the matrix effect in equine plasma were determined. Under the optimized conditions, the validated method can be applied for the identification and detection of the tetramisole enantiomers in different sources of illicit drugs of abuse.

Cocaine Use and Pulmonary Hypertension

Evidence linking cocaine to the risk of pulmonary hypertension (PH) is limited and inconsistent. We examined whether cocaine use, in the absence of other known causes of PH, was associated with elevated systolic pulmonary artery pressure (sPAP) and increased probability of PH. We compared patients with documented cocaine use to a randomly selected age, sex, and race-matched control group without history of cocaine use. All participants had no known causes of PH and underwent echocardiography for noninvasive estimation of sPAP. We used routinely reported echocardiographic parameters and contemporary guidelines to grade the probability of PH. In 88 patients with documented cocaine use (mean age ± standard deviation 51.7 ± 9.5 years), 33% were women and 89% were of Black race. The commonest route of cocaine use was smoking (74%). Cocaine users compared with the control group had significantly higher sPAP (mean ± standard deviation, 30.1 ± 13.1 vs 22.0 ± 9.8 mm Hg, p <0.001) and greater likelihood of PH (25% vs 10%, p = 0.012). In multivariable analyses adjusted for potential confounders including left ventricular diastolic dysfunction, cocaine use conferred a fivefold greater odds of echocardiographic PH (p = 0.006). Additionally, a stepwise increase in the likelihood of PH was noted across cocaine users with negative or no drug screen on the day of echocardiography to cocaine users with a positive drug screen (multivariable p for trend = 0.008). In conclusion, cocaine use was associated with a higher sPAP and an increased likelihood of echocardiographic PH with a probable acute-on-chronic effect.

Cocaine adulteration with the anthelminthic tetramisole (levamisole/dexamisole): Long-term monitoring of its intake by chiral LC-MS/MS analysis of cocaine-positive hair samples

Recent studies indicate that not only the anthelminthic levamisole but also the racemate tetramisole (R-/S-phenyltetraimidazothiazole, PTHIT) was found as an adulterant for cocaine. We herein report on the investigation of the prevalence of PTHIT among cocaine-positive hair samples and the discrimination of the presence of its stereoisomers levamisole and dexamisole. Cocaine-positive hair samples were collected in a forensic context in 2015 and mainly 2017 (n = 724). Cocaine and PTHIT concentrations have been determined by achiral liquid chromatography-tandem mass spectrometry (LC-MS/MS). For distinction of levamisole/dexamisole chiral LC-MS/MS was performed. Cocaine hair concentrations ranged from 500 (cut-off) to approximately 800 000 pg/mg. The study demonstrates a strong prevalence of PTHIT in cocaine users' hair (87%, n = 627). PTHIT hair concentrations ranged from below LLOQ 3.5 to approximately 61 000 pg/mg (median: 260 pg/mg). Surprisingly, enantiomeric ratios of levamisole/dexamisole ranged from 0.17 to 1.34 (median: 0.63). Therefore, PTHIT-adulterated street cocaine samples (n = 24) seized between 2013 and 2016 were tested. Samples mainly contained racemic tetramisole (87.5%), only one sample contained levamisole only and two samples contained non-racemic PTHIT. Our experiments suggest that the presence of tetramisole in biological samples may have hitherto been underestimated. Most probably higher dexamisole than levamisole concentrations in hair specimens arise from stereoselective metabolism and/or elimination. This is particularly important in light of the different pharmacological activities of the two enantiomers and potentially different adverse effects. Toxicological interpretations in intoxication cases with adulterated cocaine should not only consider levamisole but also tetramisole and terminology in scientific contributions should be used accordingly.