Novel assay and pharmacokinetics of levamisole and p-hydroxylevamisole in human plasma and urine

Daily compared with alternate-day levamisole in pediatric nephrotic syndrome: an open-label randomized controlled study

BACKGROUND

Levamisole is less expensive and has a better toxicity profile compared to other steroid sparing agents used in nephrotic syndrome. It has a plasma half-life of 2.0 to 5.6 hours, but is conventionally administered on alternate days. We aimed to assess whether daily levamisole is safe and more effective than standard alternate-day therapy in maintaining remission in children with frequently relapsing or steroid-dependent nephrotic syndrome (FR/SDNS).

METHODS

An open-label randomized controlled trial was conducted in children with FR/SDNS. Group A received daily while Group B received alternate-day levamisole (2-3 mg/kg/dose) for 12 months. Prednisolone was tapered off by 3 months. Patients were monitored for relapses, further steroid requirement, and adverse effects.

RESULTS

A total of 190 children with FR/SDNS (94 in Group A and 96 in Group B) were analyzed. Sustained remission for 12 months was observed in 36% of Group A and 27% of Group B patients (p = 0.18). Numbers completing 12 months in the study were 67% in Group A and 56% in Group B (p = 0.13). Time to first relapse, persistent FR/SDNS, and withdrawal due to poor compliance were statistically similar in both groups, while relapse rate and cumulative steroid dosage were significantly lower in Group A compared to Group B (p = 0.03 and p = 0.02, respectively). The incidence of adverse effects was comparable in both groups, with reversible leucopenia and hepatic transaminitis being the commonest.

CONCLUSIONS

Daily levamisole therapy was not superior to alternate-day therapy in maintaining sustained remission over 12 months. Nevertheless, relapse rate and cumulative steroid dosage were significantly lower without increased adverse effects.

Pharmacokinetic profiles and egg residue patterns of levamisole in laying hens at two dosing rates and two routes of administration

The levamisole maximum residue limit for edible fat, kidney, and muscle of chickens is 0.01 mg/kg. However, no maximum residue limit has been established for eggs. In the present study, the pharmacokinetic profile and levamisole residue in the eggs from laying hens were investigated using ultra-performance liquid chromatography-tandem mass spectrometry. A single dose of levamisole (30 mg/kg) was administered via the intramuscular or oral route, and an additional egg residue study was performed with 300 or 600 mg/kg commercial LEV drug (30 or 60 mg/kg as levamisole) orally. The limit of quantification was 0.0056 μg/mL and 0.0015 mg/kg for plasma and eggs, respectively. The plasma concentration was below the limit of quantification 10 and 12 h after intramuscular and oral administration, respectively. The half-life of the absorption phase was comparable between the intramuscular and oral routes, which was approximately 1 h, and the mean maximum concentration value was significantly higher in intramuscular (2.29 ± 0.30 μg/mL) than in oral (1.45 ± 0.38 μg/mL) route. The relative oral bioavailability after intramuscular administration was 92.3%. In the egg residue study, dose-dependent area under concentration and maximum concentration were observed after single oral administration of 30 and 60 mg/kg egg residue, and the calculated withdrawal period for both 30 and 60 mg/kg groups based on the positive list system standard (0.01 mg/kg) was 7 d after the treatment.

Improved Stability-Indicating RP-UPLC Method for the Levamisole Hydrochloride Assay and Estimation of Its Related Compounds

BACKGROUND

Levamisole hydrochloride (LVM) is an anthelmintic drug substance with immunomodulatory and anticancer activities. LVM has also found usage as a cutting agent in street cocaine.

OBJECTIVE

This study was aimed to develop and validate an alternative and improved stability-indicating reversed-phase ultraperformance liquid chromatography (RP-UPLC) method for the determination of LVM and the estimation of its related compounds.

METHOD

The UPLC method for the assay was optimized in terms of organic solvents consumed, pH, column temperature, and flow rate. Determination of LVM and its related compounds was performed using a gradient elution on a Waters ACQUITY UPLC® BEH C18 (50 mm × 2.1 mm i.d., 130 Å). The column temperature was maintained at 35°C. Mobile phase A was composed of aqueous 5 mM ammonium hydroxide, and mobile phase B was composed of acetonitrile. All the analytes were monitored by UV detection at 215 nm with a flow rate of 0.7 mL/min. The total runtime of the method with column equilibration is 4.0 min.

RESULTS

The developed method met all the acceptance criteria of the current International Council for Harmonization [ICH Q2 (R1)] guidelines. The method was tested in terms of specificity, linearity (R2 > 0.999), limit of detection (LOD; 0.06 μg/mL), limit of quantitation (LOQ; 0.2 μg/mL), accuracy, precision, and robustness. With a short analysis time (<2.5 min) and reduced consumption of organic solvents, the proposed method is considered a greener alternative to conventional chromatographic methods.

CONCLUSIONS

An alternative and improved UPLC method was successfully developed and validated in accordance with the ICH guidelines for the determination of LVM and the estimation of its related compounds.

HIGHLIGHTS

Due to its high degree of selectivity, speed, and accuracy, the developed method can significantly benefit the end-users with laboratory efficiency and throughput during routine analysis of production batches and stability monitoring of LVM-related drug products.

From Bench to Bedside: What Do We Know about Imidazothiazole Derivatives So Far?

Imidazothiazole derivatives are becoming increasingly important in therapeutic use due to their outstanding physiological activities. Recently, applying imidazothiazole as the core, researchers have synthesized a series of derivatives with biological effects such as antitumor, anti-infection, anti-inflammatory and antioxidant effects. In this review, we summarize the main pharmacological effects and pharmacological mechanisms of imidazothiazole derivates; the contents summarized herein are intended to advance the research and rational development of imidazothiazole-based drugs in the future.

Pulmonary-Renal Syndrome from Levamisole-Adulterated Cocaine-Induced Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis: A Systematic Review

Levamisole is an anti-helminthic drug with immunomodulatory properties that is added to cocaine to increase its potency and weight. Levamisole-adulterated cocaine (LAC) may cause an antineutrophil cytoplasmic antibody (ANCA)-associated systemic small vessel vasculitis (AAV). We aimed to characterize the phenotype of persons developing pulmonary-renal syndrome (PRS) in LAC-induced AAV and summarize its treatment and outcomes. Pubmed and Web of Science were searched (until September 2022). Reports that described co-existing diffuse alveolar hemorrhage and glomerulonephritis in an adult (age ≥ 18) with confirmed or suspected LAC exposure were included. Reports, demographics, clinical and serologic features, treatment and outcome characteristics were extracted. Of the 280 records identified, eight met the inclusion criteria, including eight unique cases. Persons were aged 22-58 years, and 50% were women. Cutaneous involvement occurred in only half of the cases. Other associated vasculitis findings and serologies were heterogeneous. All patients received immunosuppression with steroids, with cyclophosphamide and rituximab commonly added. We concluded that PRS could occur from LAC-induced AAV. Distinguishing LAC-induced AAV from primary AAV is challenging as clinical and serologic presentations overlap. Asking about cocaine use is requisite in persons presenting with PRS to guide diagnosis and appropriately counsel on cocaine cessation in conjunction with immunosuppression as treatment.

Biowaiver Monograph for Immediate-Release Dosage Forms: Levamisole Hydrochloride

This work describes the potential applicability of the BCS-based Biowaiver to oral solid dosage forms containing Levamisole hydrochloride, an anthelmintic drug on the WHO List of Essential Medicines. Solubility and permeability data of levamisole hydrochloride were searched in the literature and/or measured experimentally. Levamisole hydrochloride is a highly soluble drug, but there is no clear evidence of high permeability in humans, indicating that it should provisionally be assigned to BCS class III. The biowaiver procedure would thus be applicable for solid oral dosage forms containing levamisole hydrochloride as the only active ingredient. Due to the lack of data in the literature regarding excipient effects on the bioequivalence of products containing levamisole, it is currently recommended that the products comply with the ICH and WHO guidelines: the test formulation should have the same qualitative composition as the comparator, contain very similar quantities of those excipients, and be very rapidly dissolving at pH 1.2, 4.5, and 6.8. However, for certain well-studied excipients, there appears to be opportunity for additional regulatory relief in future versions of the ICH BCS Guidance M9, such as not requiring that the quantities of these common excipients in the test and comparator be the same.

Hydroxy levamisole and its phase II conjugates as potential indicators of levamisole doping in thoroughbred horses

RATIONALE

According to previous research, aminorex is the major metabolite of levamisole; however, in the screening of levamisole-positive racehorse urine and plasma samples, aminorex could only be detected in trace amounts or not at all. In forensic laboratories, hydroxy levamisole and its phase II conjugates make it easier to confirm levamisole misuse and to differentiate between the abuse of levamisole and aminorex. This study aimed to identify the major levamisole metabolites that can be detected along with the parent drug.

METHODS

The study describes levamisole and its metabolites in thoroughbred horses following oral administration and in vitro with equine liver microsomes. The plausible structures of the detected metabolites were postulated using liquid chromatography combined with high-resolution mass spectrometry.

RESULTS

Under the experimental conditions 26 metabolites (17 phase I, 2 phase II, and 7 conjugates of phase I metabolites) were detected (M1-M26). The major phase I metabolites identified were formed by hydroxylation. In phase II, the glucuronic acid conjugates of levamisole and hydroxy levamisole were detected as the major metabolites. In plasma, the parent drug and major metabolites are detectable for up to eight days, while in urine, they are detectable for up to twenty days. Levamisole levels rapidly increased at 45 min following administration, then declined gradually until detectable levels were reached approximately 8 days after administration, according to a pharmacokinetics study.

CONCLUSIONS

A prolonged elimination profile and relatively high concentration of hydroxy metabolites suggest that the detection of hydroxy metabolites is imperative for investigating levamisole doping in horses.

A Case of Cutaneous Vasculitis in the Setting of Systemic Lupus Erythematosus and Cocaine Use

Cocaine, one of most prevalent illicit substances in the United States, affects a multitude of organ systems and precedes numerous negative health outcomes. Many of the consequences of cocaine are linked to induction of vasoconstriction. For this reason, cocaine users are placed at considerable risk of ischemic stroke, myocardial infarction, and cardiac arrhythmias. Furthermore, a prominent contaminant, levamisole, has been widely implicated in predisposing individuals to developing or exacerbating cutaneous vasculitides. This report details a 31-year-old woman with acute, localized necrotic skin lesions after cocaine use. Her clinical picture was complicated by a 17-year history of systemic lupus erythematosus (SLE) and Raynaud's phenomenon. This case examines the challenge of forming a differential diagnosis, initiating an appropriate workup, and interpreting serologic-based and immunologic-based studies to differentiate between SLE and drug-based etiologies of skin necrosis. Finally, we discuss appropriate treatment plans to mitigate symptoms and reduce future instances of drug-induced vasculitis.

Metabolic Homeostasis-Regulated Nanoparticles for Antibody-Independent Cancer Radio-Immunotherapy

The special metabolic traits of cancer cells and tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) are promising targets for developing novel cancer therapy strategies, especially the glycolysis and mitochondrial energy metabolism. However, therapies targeting a singular metabolic pathway are always counteracted by the metabolic reprogramming of cancer, resulting in unsatisfactory therapeutic effect. Herein, this work employs poly(ethylene glycol)-coated (PEGylated) liposomes as the drug delivery system for both mannose and levamisole hydrochloride to simultaneously inhibit glycolysis and restrain mitochondrial energy metabolism and thus inhibit tumor growth. In combination with radiotherapy, the liposomes can not only modulate the immunosuppressive TME by cellular metabolism regulation to achieve potent therapeutic effect for local tumors, but also suppress the M2 macrophage proliferation triggered by X-ray irradiation and thus enhance the immune response to inhibit metastatic lesions. In brief, this work provides a new therapeutic strategy targeting the special metabolic traits of cancer cells and immunosuppressive TAMs to enhance the abscopal effect of radiotherapy for cancer.

Anthelmintic resistance and homeostatic plasticity (Brugia malayi)

Homeostatic plasticity refers to the capacity of excitable cells to regulate their activity to make compensatory adjustments to long-lasting stimulation. It is found across the spectrum of vertebrate and invertebrate species and is driven by changes in cytosolic calcium; it has not been explored in parasitic nematodes when treated with therapeutic drugs. Here we have studied the adaptation of Brugia malayi to exposure to the anthelmintic, levamisole that activates muscle AChR ion-channels. We found three phases of the Brugia malayi motility responses as they adapted to levamisole: an initial spastic paralysis; a flaccid paralysis that follows; and finally, a recovery of motility with loss of sensitivity to levamisole at 4 h. Motility, calcium-imaging, patch-clamp and molecular experiments showed the muscle AChRs are dynamic with mechanisms that adjust their subtype composition and sensitivity to levamisole. This homeostatic plasticity allows the parasite to adapt resisting the anthelmintic.

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.

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.

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.

Levamisole-induced vasculitis

Levamisole is a veterinary antihelminthic, chemotherapeutic agent, and immunomodulator that also is used as an adulterant and cutting agent in cocaine distribution. This drug may potentiate the sympathomimetic actions of cocaine and can cause neutropenia, agranulocytosis, purpuric retiform lesions, and skin necrosis. This article describes two cases of suspected levamisole-induced vasculitis. No standardized diagnostic or treatment algorithm exists for this challenging condition. Diagnosis and treatment require a multidisciplinary team approach.

Pharmacokinetics of levamisole in the red-eared slider turtles (Trachemys scripta elegans)

The pharmacokinetics and bioavailability of levamisole were determined in red-eared slider turtles after single intravenous (IV), intramuscular (IM), and subcutaneous (SC) administration. Nine turtles received levamisole (10 mg/kg) by each route in a three-way crossover design with a washout period of 30 days. Blood samples were collected at time 0 (pretreatment), and at 0.25, 0.5, 1, 1.5, 3, 6, 9, 12, 18, 24, 36, and 48 hr after drug administration. Plasma levamisole concentrations were determined by a high-performance liquid chromatography assay. Data were analyzed by noncompartmental methods. The mean elimination half-life was 5.00, 7.88, and 9.43 hr for IV, IM, and SC routes, respectively. The total clearance and volume of distribution at steady state for the IV route were 0.14 L hr^-1  kg^-1 and 0.81 L/kg, respectively. For the IM and SC routes, the peak plasma concentration was 9.63 and 10.51 μg/ml, respectively, with 0.5 hr of T_max . The bioavailability was 93.03 and 115.25% for the IM and SC routes, respectively. The IM and SC route of levamisole, which showed the high bioavailability and long t_1/2ʎz , can be recommended as an effective way for treating nematodes in turtles.

Estimation of the Withdrawal Time of Levamisole in Eggs after Oral Administration to Laying Hens

This study was conducted to evaluate withdrawal time of levamisole in eggs after oral administration in laying hens at different doses. Sampling of eggs was conducted for 37 days after the end of treatment, and levamisole concentrations were measured by liquid chromatography-tandem mass spectrometry validated according to the Commission Decision 2002/657/EC. Estimated validation parameters were as follows: decision limit, 0.54 μg/kg; detection capability, 0.56 μg/kg; limit of detection, 0.04 μg/kg; limit of quantification, 0.15 μg/kg; accuracy (recovery), between 92.9 and 102.3%; precision (relative standard deviation), ≤4.62%; and within-laboratory precision (relative standard deviation), ≤5.19%. Levamisole residue levels were significantly higher in egg yolks than in egg whites. The highest levels of levamisole were detected on day 2 posttreatment in groups receiving 50 mg/kg of body weight (556.2 μg/kg in egg yolks and 166.5 μg/kg in egg whites). Significant elimination occurred within 5 days after the cessation of treatment in all groups, with an elimination half-life of 1.3 days. Levamisole was still detectable on day 30 after the end of treatment in egg whites (0.06 μg/kg) and on day 37 in egg yolks (0.06 μg/kg). The longest withdrawal time for levamisole in eggs (14.9 days) was determined in a group treated with 25 mg of levamisole per kg of body weight for two consecutive days. According to the results, oral treatment of laying hens with levamisole may result in noncompliant egg samples even 14 days after treatment.

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.

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.

Levamisole: A High Performance Cutting Agent

Levamisole is an imidazothiazole chemical most frequently used as an antihelminthic agent in cattle. Over the last decade, levamisole has been increasingly encountered as an additive in both powder and crack cocaine. A white powder with a "fish scale" appearance, the chemical is physically similar to powder cocaine. In vivo, levamisole is metabolized to aminorex, a compound with amphetamine-like psychostimulatory properties and a long half-life; a priori, this property allows levamisole to potentiate and prolong the stimulatory effects of cocaine while bulking up the drug to increase profit for the dealer. As use of cocaine cut with levamisole becomes more prevalent, complications directly attributable to the chemical are increasingly being recognized.

Intra-laboratory validated human cell-based in vitro vasculogenesis/angiogenesis test with serum-free medium

Vasculogenesis and angiogenesis are the processes by which new blood vessels are formed. We have developed a serum-free human adipose stromal cell and umbilical cord vein endothelial cell based vasculogenesis/angiogenesis test. In this study, the test was validated in our GLP laboratory following the OECD Guidance Document 34 [1] using erlotinib, acetylic salicylic acid, levamisole, 2-methoxyestradiol, anti-VEGF, methimazole, and D-mannitol to show its reproducibility, repeatability, and predictivity for humans. The results were obtained from immunostained tubule structures and cytotoxicity assessment. The performance of the test was evaluated using 26 suspected teratogens and non-teratogens. The positive predictive value was 71.4% and the negative predictive value was 50.0%, indicating that inhibition of vasculogenesis is a significant mechanism behind teratogenesis. In conclusion, this test has great potential to be a screening test for prioritization purposes of chemicals and to be a test in a battery to predict developmental hazards in a regulatory context.

Levamisole-Contaminated Cocaine Use in HIV-Infected and Uninfected Unstably Housed Women

A growing number of case reports cite serious health complications linked to the cocaine adulterant, levamisole and women are disproportionately affected; however, the clinical effects are not well established. Between April and October of 2010, we conducted a cross-sectional study among 222 homeless and unstably housed women (116 human immunodeficiency virus [HIV]-infected and 106 HIV-uninfected). Immune markers and behavioral factors were compared in separate models by cocaine and levamisole exposure. Overall, 63% of participants were toxicology positive for cocaine/benzoylecgonine, 85% of whom also tested positive for levamisole. Differences in immune markers did not reach levels of significance among HIV-uninfected persons. Compared to HIV-infected persons who were negative for both cocaine and levamisole, the adjusted odds of low white blood cell count were significantly higher among HIV-infected persons positive for both (p = 0.03), but not for those positive for cocaine only. Neutrophil count and HIV viral load did not differ by cocaine and levamisole status among HIV-infected persons. In a separate model, the adjusted odds of testing positive for levamisole were higher among African American women compared to Caucasian and Asian women (p = 0.02). In the context of high levamisole prevalence, results suggest that decreased immune function as a result of levamisole exposure occurs mainly in individuals who are already immune compromised (e.g., HIV-positive), and race/ethnicity appears to be an important factor in understanding levamisole exposure among cocaine-using women. While larger and geographically diverse studies are needed to elucidate these initial findings, results suggest that levamisole may be one mechanism of immune dysfunction in HIV-infected cocaine-using women.

Cocaine/levamisole-induced systemic vasculitis with retiform purpura and pauci-immune glomerulonephritis

Levamisole has been increasingly used as an adulterant of cocaine in recent years, emerging as a public health challenge worldwide. Levamisole-associated toxicity manifests clinically as a systemic vasculitis, consisting of cutaneous, hematological, and renal lesions, among others. Purpura retiform, cutaneous necrosis, intravascular thrombosis, neutropenia, and less commonly crescentic nephritis have been described in association with anti-neutrophil cytoplasmic antibodies (ANCAs) and other autoantibodies. Here we report the case of a 49-year-old male who was a chronic cocaine user, and who presented spontaneous weight loss, arthralgia, and 3 weeks before admission purpuric skin lesions in the earlobes and in the anterior thighs. His laboratory tests on admission showed serum creatinine of 4.56 mg/dL, white blood count 3,800/μL, hemoglobin 7.3 g/dL, urinalysis with 51 white blood cells/μL and 960 red blood cells/μL, and urine protein-to-creatinine ratio 1.20. Serum ANCA testing was positive (>1:320), as well as serum anti-myeloperoxidase and anti-proteinase 3 antibodies. Urine toxicology screen was positive for cocaine and levamisole, with 62.8% of cocaine, 32.2% of levamisole, and 5% of an unidentified substance. Skin and renal biopsies were diagnostic for leukocytoclastic vasculitis and pauci-immune crescentic glomerulonephritis, respectively. The patient showed a good clinical response to cocaine abstinence, and use of corticosteroids and intravenous cyclophosphamide. Last serum creatinine was 1.97 mg/dL, white blood cell count 7,420/μL, and hemoglobin level 10.8 g/dL. In levamisole-induced systemic vasculitis, the early institution of cocaine abstinence, concomitant with the use of immunosuppressive drugs in severe cases, may prevent permanent end organ damage and associate with better clinical outcomes.

Recurrent Thrombotic Vasculopathy in a Former Cocaine User

We report a case of a 35-year-old female who presented to the emergency room (ER) complaining of a pruritic rash involving multiple areas of the body. She had a significant history of cocaine use in the past. She had first developed a similar rash in 2013 when she was diagnosed with cocaine-induced vasculitis. Her urine toxicology had been positive for cocaine in the past until July 2013. She was incarcerated and attended a drug rehabilitation program after which she quit cocaine use, which was consistent with negative urine toxicology on subsequent admissions. Further workup did not reveal any other, autoimmune or infectious, etiology of this clinical presentation. The patient underwent biopsy of the skin lesion that was consistent with thrombotic vasculopathy likely secondary to levamisole.

Necrotizing and crescentic glomerulonephritis with membranous nephropathy in a patient exposed to levamisole-adulterated cocaine

Levamisole is an antihelminthic agent widely used as an adulterant of illicit cocaine recently implicated as a cause of antineutrophil cytoplasmic antibody (ANCA)–associated microscopic polyangiitis in cocaine abusers. An isolated case of membranous nephropathy (MN) associated with levamisole exposure has also been reported. We report the first case, to our knowledge, of a patient with both microscopic polyangiitis manifest as a pauci-immune necrotizing and crescentic glomerulonephritis and concurrent MN in the setting of chronic cocaine abuse and presumed levamisole exposure, raising the hypothesis that levamisole was the causative agent in the development of this rare dual glomerulopathy.

Systemic Levamisole-Induced Vasculitis in a Cocaine User without Cutaneous Findings: A Consideration in Diagnosis

Levamisole is a known immunomodulating agent frequently used as a cutting agent in cocaine consumed in the United States today. Numerous cases of anti-neutrophil cytoplasmic antibody (ANCA) vasculitis connected with the use of levamisole-adulterated cocaine have previously been reported in the literature, classically characterized by a retiform purpuric rash. We report a case of a crack-cocaine user without cutaneous abnormalities who developed ANCA-associated glomerulonephritis that progressed to renal failure. This case demonstrates the difficulties in solidifying the diagnosis of levamisole-induced vasculitis in the absence of cutaneous findings and the need to pursue more testing to establish causality in ANCA-associated vasculitis that has potential for severe end-organ damage in patients who continue to use cocaine.

Population pharmacokinetics of levamisole in children with steroid-sensitive nephrotic syndrome

AIM

The aim was to investigate the population pharmacokinetics of levamisole in children with steroid-sensitive nephrotic syndrome.

METHODS

Non-linear mixed effects modelling was performed on samples collected during a randomized controlled trial. Samples were collected from children who were receiving 2.5 mg kg(-1) levamisole (or placebo) orally once every other day. One hundred and thirty-six plasma samples were collected from 38 children from India and Europe and included in the analysis. A one compartment model described the data well.

RESULTS

The apparent clearance rate (CL/F) and distribution volume (V/F) were 44 l h(-1) 70 kg(-1) and 236 l 70 kg(-1) , respectively; estimated interindividual variability was 32-42%. In addition to allometric scaling of CL/F and V/F to body weight, we identified a significant proportional effect of age on CL/F (-10.1% per year). The pharmacokinetics parameters were not affected by gender, tablet strength or study centre. The median (interquartile range) maximum plasma concentration of levamisole was 438.3 (316.5-621.8) ng ml(-1) , and the median area under the concentration-time curve was 2847 (2267-3761) ng ml(-1) h. Median tmax and t½ values were 1.65 (1.32-2.0) h and 2.60 (2.06-3.65) h, respectively.

CONCLUSIONS

Here, we present the first pharmacokinetic data regarding levamisole in children with steroid-sensitive nephrotic syndrome. The pharmacokinetic profile of levamisole in children was similar to findings reported in adults, although the elimination rate was slightly higher in children.

Recurrent febrile neutropenia and thrombocytopenia in a chronic cocaine user: a case of levamisole induced complications

Cocaine is used by approximately 1.5 million Americans each month and up to 69% of the cocaine seized contains levamisole. The real incidence of cocaine-levamisole induced neutropenia is unclear but probably underestimated. Associated complications include fever, thrombocytopenia, skin-vasculitis disorders, and rarely kidney injury. We present a young male, with chronic active cocaine use presenting with recurrent episodes of febrile neutropenia and thrombocytopenia. He underwent extensive work-up and was treated with many antibiotics and we suspect that his neutropenia and thrombocytopenia were caused by recurrent cocaine-levamisole use.

Tetramisole and Levamisole Suppress Neuronal Activity Independently from Their Inhibitory Action on Tissue Non-specific Alkaline Phosphatase in Mouse Cortex

Tissue non-specific alkaline phosphatase (TNAP) may be involved in the synthesis of GABA and adenosine, which are the main inhibitory neurotransmitters in cortex. We explored this putative TNAP function through electrophysiological recording (local field potential ) in slices of mouse somatosensory cortex maintained in vitro. We used tetramisole, a well documented TNAP inhibitor, to block TNAP activity. We expected that inhibiting TNAP with tetramisole would lead to an increase of neuronal response amplitude, owing to a diminished availability of GABA and/or adenosine. Instead, we found that tetramisole reduced neuronal response amplitude in a dose-dependent manner. Tetramisole also decreased axonal conduction velocity. Levamisole had identical effects. Several control experiments demonstrated that these actions of tetramisole were independent from this compound acting on TNAP. In particular, tetramisole effects were not stereo-specific and they were not mimicked by another inhibitor of TNAP, MLS-0038949. The decrease of axonal conduction velocity and preliminary intracellular data suggest that tetramisole blocks voltage-dependent sodium channels. Our results imply that levamisole or tetramisole should not be used with the sole purpose of inhibiting TNAP in living excitable cells as it will also block all processes that are activity-dependent. Our data and a review of the literature indicate that tetramisole may have at least four different targets in the nervous system. We discuss these results with respect to the neurological side effects that were observed when levamisole and tetramisole were used for medical purposes, and that may recur nowadays due to the recent use of levamisole and tetramisole as cocaine adulterants.

Antineutrophil cytoplasmic antibody mediated glomerulonephritis associated with levamisole-adulterated cocaine

Levamisole-adulterated cocaine has increased in prevalence over the last decade and is known to be associated with antineutrophil cytoplasmic antibodies (ANCA). Dermatologic manifestations of levamisole exposure, including cutaneous vasculitis, are widely appreciated; less is known about its effects on the kidney. We report two cases of patients with a history of cocaine abuse and levamisole-induced cutaneous vasculitis, who developed acute kidney injury in the setting of elevated ANCA titers. Renal biopsies of both revealed pauci-immune complex glomerulonephritis with diffuse crescentic disease. These cases demonstrate a rare but serious complication of long-term cocaine use.

Levamisole-contaminated cocaine: an emergent cause of vasculitis and skin necrosis

The prevalence of cocaine adulterated with levamisole-induced vasculitis is increasing and physicians should be aware of this unique entity. There have been many reports of cutaneous vasculitis syndrome caused by cocaine which is contaminated with levamisole. Levamisole was used as an antihelminth drug and later was rescinded from use in humans due to adverse effects. Through this paper, we will report a 39-year-old crack cocaine user who presented with purpuric rash and skin necrosis of his ear lobes. Levamisole-induced vasculitis syndrome was suspected. A urine toxicology screen was positive for cocaine, opiates, and marijuana. Blood work revealed positive titres of ANA and p-ANCA, as well as anti-cardiolipin antibody. Biopsy taken from the left ear showed focal acute inflammation, chronic inflammation with thrombus formation, and extravasated blood cells. Treatment was primarily supportive with wound care.

Passive multistate surveillance for neutropenia after use of cocaine or heroin possibly contaminated with levamisole

STUDY OBJECTIVE

To characterize the demographic, clinical, and epidemiologic features of levamisole-associated neutropenia in cocaine or heroin users.

METHODS

State health departments were recruited for participation when the Centers for Disease Control and Prevention (CDC) was notified of potential cases by a clinician, a health department official, or a poison center between October 15, 2009, and May 31, 2010. A case was defined as a person with an absolute neutrophil count less than 1,000 cells/μL (or a WBC count <2,000 cells/μL) and a self-reported history or laboratory confirmation of cocaine or heroin use. Health department officials abstracted data from medical charts, attempted a patient interview, and submitted data to CDC for descriptive analysis.

RESULTS

Of the 46 potential cases reported from 6 states, half met eligibility criteria and had medical chart abstractions completed (n=23; 50%). Of these, close to half of the patients were interviewed (n=10; 43%). The average age was 44.4 years; just over half were men (n=12; 52%). The majority of patients presented to emergency departments (n=19; 83%). More than half presented with infectious illnesses (n=12; 52%), and nearly half reported active skin lesions (n=10; 44%). The majority of interview respondents used cocaine greater than 2 to 3 times a week (n=9; 90%), used cocaine more than 2 years (n=6; 60%), and preferred crack cocaine (n=6; 60%). All were unaware of exposure to levamisole through cocaine and of levamisole's inherent toxicity (n=10; 100%).

CONCLUSION

Physicians should suspect levamisole exposure in patients using illicit drugs, cocaine in particular, who present with unexplained neutropenia. Most patients reported chronic cocaine use and were unaware of levamisole exposure. Cocaine use is more prevalent among men; however, our results identified a higher-than-expected proportion of female users with neutropenia, suggesting women may be at higher risk. Emergency physicians and practitioners are uniquely positioned to recognize these patients early during their hospital course, elucidate a history of cocaine or other drug exposure, and optimize the likelihood of confirming exposure by arranging for appropriate drug testing.

Cutaneous vasculopathy associated with levamisole-adulterated cocaine

We report a case of cutaneous vasculopathy associated with the use of levamisole-adulterated cocaine. This recently described clinical entity is characterized by a purpuric rash with a predilection for the ears, leukopenia, and anti-neutrophilic cytoplasmic antibody (ANCA) positivity. It is estimated that more than 70% of the current United States cocaine supply is contaminated with levamisole. Levamisole is a widely available, inexpensive, white powder used as a "cutting agent" in cocaine to expand volume and increase profits. It may also increase the euphoric and stimulatory effects of cocaine by increasing brain dopamine levels and producing amphetamine-like metabolites. Our patient exhibited a characteristic rash with involvement of the ears, leukopenia, and cocaine metabolites were detected in serum and urine. The presence of levamisole was confirmed in the urine utilizing gas chromatography-mass spectrometry. ANCA positivity was also present. Punch biopsy of the skin demonstrated vascular thrombosis and necrosis without true vasculitis. We review the literature for reported cases of cocaine-levamisole cutaneous vasculopathy syndrome, highlight the salient immunologic abnormalities, and contrast the features of this entity with idiopathic systemic vasculitis.

How to spot cocaine-induced pseudovasculitis

The prevalence of cocaine-induced pseudovasculitis (CIP) causing cutaneous destruction is increasing, and plastic surgeons need to be aware of this condition because they are a part of the multidisciplinary treatment team. Differentiation of CIP from a true autoimmune vasculitis can be exceedingly challenging, and misdiagnosis with ensuing treatment may be fatal. This article is a succinct review of CIP, guided by a clinical case of 30% total body surface area skin necrosis, to familiarize the reader with this syndrome. Diagnostic aids include history of cocaine use, localized disease manifestation to skin or mucosa, discordance of antineutrophil cytoplasmic antibody and target antibody patterns typical for true vasculitis, and testing for antihuman neutrophil elastase and levamisole. Treatment is primarily supportive, and wound care, with regard to dressings and surgery, is a cross between to that of burns and meningococcemia patients.

The head, neck, and systemic manifestations of levamisole-adulterated cocaine use

Systemic complications of levamisole-adulterated cocaine (LAC) use have recently been described. The objective of this review is to increase awareness of these manifestations among oral and maxillofacial surgeons. LAC exposure through inhalation, nasal insufflation, or injection can induce cutaneous vasculopathy and hematologic abnormalities such as neutropenia or agranulocytosis. Unlike other vasculopathies involving the skin, LAC-induced vascular injury frequently manifests with purpuric and necrotic lesions that involve the face and ears. Oral manifestations have also been reported but are not yet well characterized. The aforementioned hematologic manifestations are not uncommon, and patients exposed to LAC are potentially at higher risk for infectious complications. When manifestations of LAC affect the head, neck, and oral cavity, oral and maxillofacial surgeons may be the first providers to encounter the patient. Early recognition of the clinical signs and laboratory abnormalities will better allow for distinguishing LAC-related effects from various clinical mimics, will facilitate appropriate patient management, and may further contribute to the understanding of the biological effects of LAC.

Lupus anticoagulant and ANCA associated thrombotic vasculopathy due to cocaine contaminated with levamisole: a case report and review of the literature

A 2010 US report recently detected the presence of levamisole in greater than 77 % of seized cocaine samples. A syndrome of retiform purpura, often involving ears and flanks, with vasculopathy or vasculitis on biopsy, associated with anti-nuclear cytoplasmic antibodies as well as antiphospholipid antibodies, previously associated with therapeutic use of levamisole has now re-emerged, and is associated with cocaine adulterated with levamisole. Patients with this unusual constellation of signs and laboratory findings should be questioned about exposure to cocaine.

Palpable purpura complicated by streptococcal toxic shock syndrome resulting in limb necrosis and amputation: a case of levamisole and cocaine coingestion

Palpable purpura resulting from cocaine and levamisole coingestion has been reported with increasing frequency over the last several years as distribution of this drug combination becomes more universal. Toxicity from ingestion of this dangerous combination is difficult to diagnose due to the multitude of possible clinical presentations, variety of possible adulterants, and elusive nature of levamisole given its short half-life and limited availability of detection methods. Levamisole is a chemotherapeutic and immunomodulatory agent currently marketed as a veterinary anthelmintic. We describe the case of a 48-year-old woman admitted to our intensive care unit with a diagnosis of streptococcal toxic shock syndrome (STSS), confirmed from fluid taken from an elbow lesion that grew Streptococcus pyogenes. She was noted to have bullae of the elbow and diffuse purpura with necrotic centers covering a large portion of her body (trunk, legs, arms, back, toes, fingers, and tip of nose). On further evaluation, she was found to have ingested levamisole-tainted cocaine. The patient's complications related to either cocaine and levamisole coingestion or STSS included thrombocytopenia, acute renal failure, and limb necrosis. Thrombocytopenia gradually improved upon treatment with prednisone, and acute renal failure improved with intravenous fluid resuscitation; however, she subsequently required several appendage amputations due to severe gangrene. Clinicians must have high suspicion for ingestion of this drug combination and request prompt testing of urine samples for levamisole if a patient who admits to illicit drug use presents with purpuric or necrotic skin lesions.

Determination of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry on an ion trap

Test methods have to be developed by laboratories for official control to monitor possible misuse of veterinary drugs in animal productions, also through feeding stuff. A novel method for identification and quantification of levamisole in feeds by liquid chromatography coupled to electrospray mass spectrometry in an ion trap (LC/ESI-MS/MS) is herein described; after a single-step cleanup by liquid-liquid extraction from the feed and separation by reversed-phase liquid chromatography, levamisole was determined and unambiguously confirmed by tandem mass spectrometry, on the basis of two product ions. The method was in-house validated, according to the Regulation 882/2004/EC, evaluating trueness, repeatability, within-laboratory reproducibility, ruggedness, specificity, and the limit of quantification (LOQ). The method is reliable and specific for complete and complementary feeds for pigs, cattle, rabbits and poultry; very good mean recoveries (higher than 92 %) and precision (RSD values < 15.2%) were attained. The LOQ at 2.0 mg/kg was verified. Moreover, we describe how the method was developed to support Italian Police investigations regarding illegal treatments of pigs; in this case, since the drug(s) added to the feed were unknown, a preliminary untargeted analysis was performed by full scan mass spectrometry on an ion trap, from 50 up to 2000 m/z; the presence of levamisole was hypothesised, on the basis of the most abundant ion and its fragmentation pattern. Then, levamisole was unambiguously confirmed by the ion trap LC/ESI-MS/MS method.

Immune-mediated agranulocytosis caused by the cocaine adulterant levamisole: a case for reactive metabolite(s) involvement

The United States Public Health Service Administration is alerting medical professionals that a substantial percentage of cocaine imported into the United States is adulterated with levamisole, a veterinary pharmaceutical that can cause blood cell disorders such as severe neutropenia and agranulocytosis. Levamisole was previously approved in combination with fluorouracil for the treatment of colon cancer; however, the drug was withdrawn from the U.S. market in 2000 because of the frequent occurrence of agranulocytosis. The detection of autoantibodies such as antithrombin (lupus anticoagulant) and an increased risk of agranulocytosis in patients carrying the human leukocyte antigen B27 genotype suggest that toxicity is immune-mediated. In this perspective, we provide an historical account of the levamisole/cocaine story as it first surfaced in 2008, including a succinct review of levamisole pharmacology, pharmacokinetics, and preclinical/clinical evidence for levamisole-induced agranulocytosis. Based on the available information on levamisole metabolism in humans, we propose that reactive metabolite formation is the rate-limiting step in the etiology of agranulocytosis associated with levamisole, in a manner similar to other drugs (e.g., propylthiouracil, methimazole, captopril, etc.) associated with blood dyscrasias. Finally, considering the toxicity associated with levamisole, we propose that the 2,3,5,6-tetrahydroimidazo[2,1-b]thiazole scaffold found in levamisole be categorized as a new structural alert, which is to be avoided in drug design.