Xylazine (veterinary sedative) use in Puerto Rico

Xylazine in the Unregulated Drug Market: An Integrative Review of Its Prevalence, Health Impacts, and Detection and Intervention Challenges in the United States

Xylazine, a veterinary sedative, has emerged as a concerning element in the landscape of substance use in the United States. This integrative review synthesizes evidence from a systematic examination of 14 selected studies conducted between 2008 and 2023. The primary objective is to comprehensively understand the epidemiology and prevalence of xylazine use, particularly its involvement in drug-related deaths, regional variations, national impact, co-occurrence with opioids, and challenges associated with detection and intervention. The results underscore stark regional disparities in xylazine prevalence. West Virginia and Miami-Dade County have experienced alarming surges in xylazine-involved drug-related deaths. Nationally, its influence extends beyond regional boundaries, predominantly affecting white males in the Northeast. The co-occurrence of xylazine with opioids, especially fentanyl and heroin, significantly amplifies the risks of fatal overdoses. Detecting xylazine presents formidable challenges due to its frequent presence alongside other substances, necessitating enhanced surveillance and more effective detection methods. User perspectives emerge as pivotal, emphasizing the importance of user-informed harm reduction strategies. In conclusion, this review has significant policy implications. Tailored, region-specific strategies are imperative to address the diverse prevalence of xylazine use. A nationwide response is indispensable, prioritizing harm reduction initiatives, enhanced detection methods, and active user engagement. The multifaceted nature of the xylazine issue requires comprehensive approaches to mitigate its profound risks effectively. Policymakers are urged to consider regional disparities and the co-occurrence of xylazine with opioids when crafting targeted interventions. Immediate, user-informed harm reduction is vital to address the evolving landscape of xylazine use in the United States.

Tranq Dope: Characterization of an ED cohort treated with a novel opioid withdrawal protocol in the era of fentanyl/xylazine

BACKGROUND

Treating opioid use disorder has reached a new level of challenge. Synthetic opioids and xylazine have joined the non-medical opioid supply, multiplying the complexities of caring for individuals in emergency departments (ED). This combination, known as 'tranq dope,' is poorly described in literature. Inadequate withdrawal treatment results in a disproportionately high rate of patient-directed discharges (also known as against medical advice dispositions, or AMA). This study aimed to describe a cohort of individuals who received a novel order set for suspected fentanyl and xylazine withdrawal in the ED.

METHODS

This is a descriptive study evaluating a cohort of ED patients who received withdrawal medications from a novel protocol and electronic health record order set. Individuals being assessed in the ED while suffering from withdrawal were eligible. Individuals under age 18, on stable outpatient MOUD or who were pregnant were excluded. Treatment strategies included micro-induction buprenorphine, short acting opioids, non-opioid analgesics, and other adjunctive medications. Data collected included: demographics including zip code, urine toxicology screening, order set utilization and disposition data. Clinical Opiate Withdrawal Scale (COWS) scores were recorded, where available, before and following exposure to the medications.

RESULTS

There were 270 patient encounters that occurred between September 14, 2022, and March 9, 2023 included in the total study cohort. Of those, 66 % were male, mean age 37 with 71 % residing within Philadelphia zip codes. 100 % of urine toxicology screenings were positive for fentanyl. Of the 177 patients with both pre- and post-exposure COWS scores documented, constituting the final cohort, patients receiving medications had their COWS score decrease from a median of 12 to a median of 4 (p < 0.001). The AMA rate for this cohort was 3.9 %, whereas the baseline for the population with OUD was 10.7 %. Recorded adverse effects were few and resolved without complication.

CONCLUSIONS

Fentanyl and xylazine withdrawal are challenging for patients and providers. A novel tranq dope withdrawal order set may reduce both COWS scores and rate of patient-directed discharge in this cohort of patients, though further investigation is needed to confirm findings.

Drug use practices and wound care experiences in the age of xylazine adulteration

INTRODUCTION

Exposure to xylazine has been associated with wounds distinct from typical injection-related skin and soft tissue infections. We sought to understand drug use and wound care practices, and treatment experiences of people who use drugs (PWUD) in a high-prevalence area of xylazine adulteration.

METHODS

In August 2023, we surveyed adult PWUD reporting at least one past-year drug use-related wound across three Massachusetts syringe service programs. Using a representative illustration, participants indicated if they had experienced a xylazine wound in the past 90 days. We compared demographic, drug use factors, wound care, and medical treatment experiences among those with and without xylazine wounds. We also conducted additional content analysis of open-ended responses.

RESULTS

Of the 171 respondents, 87 % (n=148) had a xylazine wound in the past 90 days. There were no statistically significant demographic differences between those with and without xylazine wounds. Among those primarily injecting (n=155), subcutaneous injection was nearly ten times more likely among people with xylazine wounds. For those with xylazine wounds (n=148), many engaged in heterogeneous wound self-treatment practices, and when seeking medical care, 74 % experienced healthcare stigma and 58 % had inadequate pain and withdrawal management.

CONCLUSION

People with self-identified xylazine wounds were more likely to engage in subcutaneous injection and faced several barriers seeking medical wound treatment. Programs serving people exposed to xylazine should work to support safer injection practices, including alternatives to injecting and improving access to high-quality, effective wound care. Further study is warranted to understand the causes, promoters, and prevention of xylazine-related wounds.

Syringe services program staff and participant perspectives on changing drug consumption behaviors in response to xylazine adulteration

BACKGROUND

Xylazine is an increasingly common adulterant in the North American unregulated drug supply that is associated with adverse health outcomes (e.g., skin infections, overdose). However, there are significant knowledge gaps regarding how xylazine was initially identified and how syringe services program (SSP) staff and clients (people who use drugs) responded to its emergence.

METHODS

From June-July 2023, we conducted qualitative interviews with medical (e.g., clinicians) and frontline SSP staff (e.g., outreach workers) and adult clients with a history of injection drug use at a Miami-based SSP. Inductive memos identified emergent codes; thematic analysis involving team consensus established final themes.

RESULTS

From interviews with SSP staff (n = 8) and clients (n = 17), xylazine emergence was identified at different times, in various ways. Initially, during summer 2022, clients identified a "tranquilizer-like substance" that worsened sedation and withdrawal and caused wounds. SSP medical staff later identified this adulterant as xylazine by treating new medical cases and through diverse information-sharing networks that included professional societies and news sources; however, frontline SSP staff and clients needed additional educational resources about xylazine and its side effects. With limited guidance on how to reduce harm from xylazine, SSP clients altered their drug consumption routes, reduced drug use, and relied on peers' experiences with the drug supply to protect themselves. Some individuals also reported preferring xylazine-adulterated opioids and increasing their drug use, including the use of stimulants to avoid over sedation.

CONCLUSIONS

Xylazine's emergence characterizes the current era of unprecedented shifts in the unregulated drug supply. We found that xylazine spurred important behavioral changes among people who use drugs (e.g., transitioning from injecting to smoking). Incorporating these experiences into early drug warning surveillance systems and scaling up drug-checking services and safer smoking supply distribution could help mitigate significant health harms caused by xylazine and other emergent adulterants.

Evolution of the substance use landscape: Implications for contingency management

Contingency management (CM), which involves the delivery of incentives upon meeting behavioral goals, has the potential to improve substance use treatment outcomes. The intervention allows for flexibility through numerous modifiable components including changes to incentive magnitude and schedule, target behavior, and intervention structure. Unfortunately, numerous changes in the substance use landscape have occurred in the past 10 to 15 years: Substances are more potent, overdose risk has increased, new substances and methods of use have been introduced, and substance classes are increasingly being intentionally and unintentionally mixed. These developments potentially undermine CM outcomes. We explored recent substance use changes due to legislative, regulatory, social, and economic factors for four substance classes: stimulants, opioids, tobacco, and cannabis. We discuss potential adjustments to the modifiable components of CM for future research in response to these changes. By continually adapting to the shifting substance use landscape, CM can maintain optimal efficacy.

Management of Xylazine-Induced Soft-Tissue Necrosis: A Review of 20 Cases

PURPOSE

The illicit injection of xylazine has recently been designated as an emerging public health threat. The use of this drug is associated with devastating soft-tissue necrosis that may lead to limb amputation. This study aimed to (1) report cases of soft-tissue injury from xylazine and (2) describe a staging and management algorithm for wounds related to xylazine use.

METHODS

A retrospective review was conducted to identify patients treated for xylazine-related soft-tissue necrosis at a trauma center. Clinical cases, treatment strategy, and available outcomes were presented. In addition, a comprehensive literature search was conducted using the keywords "xylazine" and "soft tissue."

RESULTS

The management of seven patients with xylazine-related upper extremity soft-tissue necrosis was included, in addition to summarizing findings of five studies reporting on 13 additional cases. These cases were managed with local wound care (2 patients), soft-tissue reconstruction (4 patient), osseous reconstruction (1 patient), and limb amputation (10 patients).

DISCUSSION

Acute treatment of xylazine-related soft-tissue necrosis is ideal to minimize morbidity and prevent limb loss. Management strategies of these wounds should be based on the depth of tissue involvement. Superficial ulceration involving the skin and subcutaneous tissue (Stage 1) should be managed with local wound care. Deeper ulceration involving tendons and/or muscle (Stage 2) requires surgical débridement and soft-tissue reconstruction. Deeper ulceration involving bone (Stage 3) requires osseous débridement and reconstruction. Finally, when all tissues in the extremity are involved (Stage 4), amputation is often necessary.

Providers' knowledge and perception of xylazine in the unregulated drug supply: a sequential explanatory mixed-methods study

BACKGROUND

Xylazine is increasingly prevalent in the unregulated opioid supply in the United States. Exposure to this adulterant can lead to significant harm, including prolonged sedation and necrotic wounds. In the absence of literature describing healthcare providers' experiences with treating patients who have been exposed to xylazine, we aimed to explore what gaps must be addressed to improve healthcare education and best practices.

METHODS

From October 2023 to February 2024, we conducted a sequential explanatory mixed-methods study, with (1) a quantitative survey phase utilizing convenience sampling of healthcare providers treating patients in Connecticut and (2) a qualitative semi-structured interview phase utilizing purposive sampling of providers with experience treating patients with xylazine exposure. Summary statistics from the survey were tabulated; interview transcripts were analyzed using thematic analysis.

RESULTS

Seventy-eight eligible healthcare providers participated in our survey. Most participants had heard of xylazine (n = 69, 95.8%) and had some knowledge about this adulterant; however, fewer reported seeing one or more patients exposed to xylazine (n = 46, 59.8%). After sampling from this subgroup, we conducted fifteen in-depth interviews. This qualitative phase revealed five themes: (1) while xylazine is novel and of concern, this is not necessarily exceptional (i.e., there are other emerging issues for patients who use drugs); (2) participants perceived that xylazine was increasingly prevalent in the drug supply, even if they were not necessarily seeing more patients with xylazine-related outcomes (XROs); (3) patients primarily presented with non-XROs, making it difficult to know when conversations about xylazine were appropriate; (4) patients with XROs may experience issues accessing healthcare; (5) providers and their patients are learning together about how to minimize XROs and reduce the sense of helplessness in the face of a novel adulterant.

CONCLUSIONS

Xylazine-specific education for healthcare providers is currently insufficient. Improving this education, as well as resources (e.g., drug checking technologies) and data (e.g., research on prevention and treatment of XROs), is crucial to improve care for patients who use drugs.

Protective or potentially harmful? Altering drug consumption behaviors in response to xylazine adulteration

Background

Xylazine is an increasingly common adulterant in the North American unregulated drug supply that is associated with adverse health outcomes (e.g., skin infections, overdose). However, there are significant knowledge gaps regarding how xylazine was initially identified and how syringe services program (SSP) staff and clients (people who use drugs) responded to its emergence.

Methods

From June-July 2023, we conducted qualitative interviews with medical (e.g., clinicians) and frontline SSP staff (e.g., outreach workers) and adult clients with a history of injection drug use at a Miami-based SSP. Inductive memos identified emergent codes; thematic analysis involving team consensus established final themes.

Results

From interviews with SSP staff (n = 8) and clients (n = 17), xylazine emergence was identified at different times, in various ways. Initially, during summer 2022, clients identified a "tranquilizer-like substance" that worsened sedation and withdrawal and caused wounds. SSP medical staff later identified this adulterant as xylazine by treating new medical cases and through diverse information-sharing networks that included professional societies and news sources; however, frontline SSP staff and clients needed additional educational resources about xylazine and its side effects. With limited guidance on how to reduce harm from xylazine, SSP clients altered their drug consumption routes, reduced drug use, and relied on peers' experiences with the drug supply to protect themselves. Some individuals also reported preferring xylazine-adulterated opioids and increasing their drug use, including the use of stimulants to avoid over sedation.

Conclusions

Xylazine's emergence characterizes the current era of unprecedented shifts in the unregulated drug supply. We found that xylazine spurred important behavioral changes among people who use drugs (e.g., transitioning from injecting to smoking). Incorporating these experiences into early drug warning surveillance systems and scaling up drug-checking services and safer smoking supply distribution could help mitigate significant health harms caused by xylazine and other emergent adulterants.

Trace Detection of Adulterants in Illicit Opioid Samples Using Surface-Enhanced Raman Scattering and Random Forest Classification

The detection of trace adulterants in opioid samples is an important aspect of drug checking, a harm reduction measure that is required as a result of the variability and unpredictability of the illicit drug supply. While many analytical methods are suitable for such analysis, community-based approaches require techniques that are amenable to point-of-care applications with minimal sample preparation and automated analysis. We demonstrate that surface-enhanced Raman spectroscopy (SERS), combined with a random forest classifier, is able to detect the presence of two common sedatives, bromazolam (0.32-36% w/w) and xylazine (0.15-15% w/w), found in street opioid samples collected as a part of a community drug checking service. The Raman predictions, benchmarked against mass spectrometry results, exhibited high specificity (88% for bromazolam, 96% for xylazine) and sensitivity (88% for bromazolam, 92% for xylazine) for the compounds of interest. We additionally provide evidence that this exceeds the performance of a more conventional approach using infrared spectral data acquired on the same samples. This demonstrates the feasibility of SERS for point-of-care analysis of challenging multicomponent samples containing trace adulterants.

Xylazine is an agonist at kappa opioid receptors and exhibits sex-specific responses to opioid antagonism

Xylazine is in the unregulated drug supply at increasing rates, usually combined with fentanyl, necessitating understanding of its pharmacology. Despite commentary from politicians, and public health officials, it is unknown how xylazine impacts naloxone efficacy, and. few studies have examined it alone. Here, we examine the impact of xylazine alone and in combination with fentanyl on several behaviors in mice. Surprisingly, naloxone precipitates withdrawal from xylazine and fentanyl/xylazine coadministration, with enhanced sensitivity in females. Further, xylazine is a full agonist at kappa opioid receptors, a potential mechanism for its naloxone sensitivity. Finally, we demonstrate surprising effects of xylazine to kappa opioid antagonism, which are relevant for public health considerations. These data address an ongoing health crisis and will help inform critical policy and healthcare decisions.

Necrotic Upper-Extremity Infections in People Who Inject Drugs: A Case Series

PURPOSE

Our institution has noted an increase in severe upper-extremity infections within the last 2 years. These patients have required transhumeral amputation. This case series demonstrates some of the catastrophic outcomes of these infections in people who inject drugs, which has been postulated to be related to the addition of xylazine to injectable drugs in our community.

METHODS

The study included patients presenting with severe upper-extremity infections resulting from intravenous drug use and requiring upper-extremity amputation between January 1, 2020 and September 30, 2022 at a single, urban, level 1 trauma center. Patient information and clinical images were collected through retrospective chart review.

RESULTS

Eight patients were identified at our institution with extensive necrosis of the skin and soft tissues in the forearm and hand, resulting in exposure of the radius and ulna. None of these patients had viable motor function in the hand and presented with a lack of sensation. All underwent transhumeral amputations, including bilaterally in one case.

CONCLUSIONS

The patients in this case series self-reported injection of tranquilizer-containing drugs, and xylazine has been reported to be present in 91% of heroin and fentanyl samples in our community. Although more studies are needed to confirm that xylazine is the definitive cause of the extensive tissue necrosis seen in these patients, we have found the severity of these infections to be noteworthy, given the likely expansion of xylazine to drug samples beyond our region.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Xylazine and Adulterants in the Evolving Drug Supply: Urgent Call for Responsive Education Models

Novel adulterants and synthetic substances are rapidly infiltrating the US drug supply causing new clinical harms. There is an urgent need for responsive education and training to address these evolving harms and mitigate new risks. Since 2020, xylazine, a veterinary tranquilizer, has become increasingly common in the illicit opioid supply, especially alongside fentanyl. Training and technical assistance (TTA) programs employing an adaptive model can quickly disseminate emerging information and provide the tools to respond effectively. We describe our TTA program's experience developing and delivering virtual instructor-led xylazine training to a diverse group of addiction care professionals. The training objectives included the following: (1) introducing epidemiologic trends, pharmacology, and existing literature related to xylazine; (2) reviewing xylazine-associated harms and management; and (3) discussing harm reduction strategies related to xylazine use. We conducted 14 training sessions between October 2022 and July 2023, which were attended by over 2000 individuals across 49 states. We review our experience developing innovative training content and managing flexible training logistics and highlight our lessons learned, including targeting multidisciplinary professionals, leveraging online synchronous delivery methods, and a need for sustainable funding for TTA programs.

Xylazine-Associated Wounds and Related Health Concerns Among People Who Use Drugs: Reports From Front-Line Health Workers in 7 US States

BACKGROUND

Xylazine, an adrenergic alpha-2 agonist increasingly present in the US drug supply, is associated with severe skin ulcers and other harms. Expert knowledge from front-line harm reduction and healthcare professionals is an essential component of evidence-based practice. The purpose of this study is to describe the progression and treatment of xylazine-associated wounds, other xylazine-related health concerns, and the most urgent research priorities as reported by front-line harm reduction and healthcare professionals serving people who use drugs.

METHODS

A convenience sample of 17 healthcare and harm reduction professionals who serve people who use drugs in the US states of Maryland, Massachusetts, Michigan, Minnesota, North Carolina, Pennsylvania, and Texas participated in semi-structured interviews. Participants were asked about the appearance and progression of xylazine-associated wounds; preferred treatment strategies; other xylazine-related harms experienced by people who use drugs; and the most urgent priorities for xylazine-related research.

FINDINGS

Xylazine-associated wounds were broadly described as small lesions appearing mostly on extremities both at and away from injection sites, often within hours or days of exposure, that quickly developed into large, complex, chronic wounds. Reported risk of secondary infection was generally low but appeared more common among unhoused populations. Most participants preferred conservative treatment strategies that included regular wound care, enzymatic debridement, and hygiene. Xylazine-associated wounds and xylazine withdrawal reportedly act as significant barriers to care, including addiction treatment. Participants reported urgent need for scientific research and evidence-based guidance on the management of xylazine-associated wounds and withdrawal.

CONCLUSIONS

High-quality scientific evidence on risk factors for xylazine-associated wounds and on their biologic mechanisms is needed. Such studies could inform new strategies for the prevention and treatment of these wounds. Efforts to improve the management of xylazine withdrawal and to reduce stigma by incorporating harm reduction professionals into healthcare settings may improve access to and retention in care.

Media framing xylazine as a "zombie drug" is amplifying stigma onto people who use drugs

Amid increasing efforts to understand xylazine-associated harms, examining the potentially catastrophic role of stigma resulting from media outlets framing xylazine as the "zombie drug" is imperative. Zombies are cinematically depicted as soulless, dangerous, and required to be killed off entirely for public safety, making the "zombie" analogy especially grave amid the fatal overdose crisis. Xylazine is called the "zombie drug" due to its heavy sedative effect and associated-severely infected skin ulcers. We surmise that wide-scale media framing of xylazine as the "zombie drug" has increased stigmas onto people who use drugs as their likening to zombies reifies subhuman status. The present commentary highlights many media headlines and quotes that use "zombie" terminology when writing about xylazine, and examine how this expansive media framing amplifies stigmas. Xylazine's proliferation in the illicit drug market will likely increase infected ulcers needing medical attention. People who use drugs are often reluctant to seek medical care due to experiences of medically-institutionalized stigma. Based on the media's extensive depiction of xylazine as the "zombie drug," it is plausible that medical practitioners have been exposed to this stigmatizing framing, which could unknowingly detrimentally impact provision of medical care. Strategies to offset harms of xylazine-associated stigmas are proposed, including that medical practitioners undergo evidence-based training to reduce stigmatizing responses to severe xylazine-associated ulcers as any indication of enacted stigma can be internalized by the person seeking treatment, which in turn can perpetuate harms like sepsis or overdose. Author ethnographic observations of xylazine presence are included, which encompass three distinct urban settings that span North America. Finally, we suggest approaches media outlets could adopt to reflect on how referring to xylazine as the "zombie" drug amplifies stigmas onto people already surviving under structural conditions heightening physical and mental trauma, and use language instead that could aid in lessening these harms.

Mucocutaneous Manifestations of Recreational Drug Use

Recreational drug use is increasingly common in the dermatology patient population and is often associated with both general and specific mucocutaneous manifestations. Signs of substance use disorder may include changes to general appearance, skin, and mucosal findings associated with particular routes of drug administration (injection, insufflation, or inhalation) or findings specific to a particular drug. In this review article, we provide an overview of the mucocutaneous manifestations of illicit drug use including cocaine, methamphetamine, heroin, hallucinogens, marijuana, and common adulterants to facilitate the identification and improved care of these patients with the goal being to connect this patient population with appropriate resources for treatment.

N-desethyl isotonitazene detected in polydrug users admitted to hospital in Birmingham, United Kingdom

INTRODUCTION

Nitazenes are potent synthetic opioids and N-desethyl isotonitazene, a metabolite of isotonitazene, has emerged as a drug in its own right.

METHODS

This is an observational case series of patients with suspected or declared substance use who were admitted to hospitals in the Sandwell and West Birmingham National Health Service Trust between July and October 2023. All patients were found on toxicological screening to have been exposed to N-desethyl isotonitazene.

RESULTS

Twenty presentations involving 19 patients who tested positive for N-desethyl isotonitazene were included in the study. In 19 presentations, multiple substances were detected on toxicological screening. The number of patients testing positive for other substances were: 19 for cocaine and its main metabolite benzoylecgonine, 13 for morphine, 11 for the heroin-specific metabolite 6-monoacetylmorphine, ten for xylazine, eight for gabapentinoids (pregabalin and/or gabapentin), seven for methadone and/or the metabolite, 2-ethylidene-1, 5-dimethyl-3, 3-diphenylpyrrolidine, six for benzodiazepines and five for the synthetic cannabinoid MDMB-4en-PINACA. Only one patient had no other substances detected apart from N-desethyl isotonitazene. This patient presented with coma, miosis, bradypnoea and hypercapnia and responded to naloxone. In this cohort, the median concentration of N-desethyl isotonitazene was 1.53 µg/L (n = 14; range 0.59-5.48) in whole blood and 27.75 µg/L (n = 16; range 0.51-91.53) in urine.

DISCUSSION

The majority of the patients in this cohort presented with features typical of an opioid overdose, which is unsurprising as they were all experienced users of diamorphine. Although these features are also consistent with the known effects of N-desethyl isotonitazene, in only one case is it possible to attribute the patient's features to N-desethyl isotonitazene toxicity alone.

CONCLUSIONS

This case series highlights the need for toxicovigilance in the illicit drug market as patterns of substance misuse evolve and novel psychoactive substances continue to emerge.

Evaluation of the relationship of xylazine and fentanyl blood concentrations among fentanyl-associated fatalities

INTRODUCTION

Illicit fentanyl and fentanyl-analogs have produced a devastating increase in opioid fatalities in the United States. Increasingly, xylazine has been found in the illicit fentanyl supply. The role of xylazine in fentanyl intoxication remains unclear. We reviewed coroner records to evaluate trends and effects associated with xylazine in fentanyl-related fatalities.

METHODS

This is a retrospective cohort study of all deaths reported to the Franklin County Coroner's Office in Ohio from 1 January 2019 to 16 March 2023, in which fentanyl was determined causative or contributory to death. Cases identified as fentanyl-associated fatalities were separated into two groups based on whether or not xylazine was also detected.

RESULTS

There were 3,052 fentanyl-related fatalities during the study period. 4.8 percent of these decedents also tested positive for xylazine. There was no meaningful demographic difference between fentanyl-related fatalities in which xylazine was detected versus those without xylazine detected. There was a mean of 726 fentanyl-associated fatalities per year, with a peak of 846 deaths in 2020 and a decline thereafter. The percentage of fentanyl-related fatalities with xylazine detected increased in linear fashion from 2.7 percent in 2019 to 6.6 percent in 2022. The median fentanyl concentration was 17.0 µg/L (inter-quartile range: 7.9, 27.0) in cases with xylazine detected and 10.0 µg/L (inter-quartile range: 5.6, 18.0) without xylazine. The odds of a fentanyl concentration greater than 40 µg/L in cases with xylazine detected was more than twice as great (odds ratio: 2.41; 95 percent confidence interval: 1.58-3.64) than that in cases without xylazine detected.

CONCLUSIONS

Postmortem fentanyl concentrations were greater in cases with xylazine detected than those without xylazine detected. Though it is unclear why patients who were exposed to xylazine tolerated higher opioid doses prior to succumbing to death, we postulate that xylazine may act to competitively antagonize some degree of mu-opioid receptor binding by opioids.

Recognition and Treatment of Wounds in Persons Using Xylazine: A Case Report From New Haven, Connecticut

BACKGROUND

Xylazine is an α 2 -adrenergic agonist that is commonly used as a veterinary tranquilizer and is increasingly present in the unregulated US drug supply since at least 2019. There are many suspected clinical complications of xylazine use, including unusual skin wounds, atypical overdose presentations, and possible dependence and withdrawal syndromes. However, there are few reports of cutaneous manifestations of xylazine in patients who inject drugs that can guide diagnosis and management in patients with confirmed xylazine toxicology.

CASE SUMMARY

We present the cases of 3 stably housed patients in Connecticut with opioid use disorder and intravenous use of fentanyl who presented with atypical, chronic wounds at the site of injection drug use. Xylazine toxicology sent on all 3 patients was positive. All patients were seen by wound care and dermatology, and 1 patient was followed by infectious diseases. Wound care management strategies are discussed as well as harm reduction strategies. For all patients, the dose of their medication for opioid use disorder was increased to decrease frequency of drug use given concern that patients were exposed to a drug supply containing xylazine.

CLINICAL SIGNIFICANCE

This case report presents wound characteristics that raise the index of suspicion for xylazine-involved injection wounds and might assist in their diagnosis and management. There is urgent need for more reporting of such cases as well as rigorous research to understand the potential impact of xylazine on people who use drugs. Multidisciplinary best practices should be established.

Xylazine Adulteration of the Heroin-Fentanyl Drug Supply : A Narrative Review

Xylazine is an animal sedative, approved by the U.S. Food and Drug Administration, that is commonly used in veterinary medicine and is not approved for human use. Since 2016, xylazine has consistently appeared in the illicitly manufactured fentanyl supply and has significantly increased in prevalence, likely due to its low cost, easy availability, and presumed synergistic psychoactive effect. Clinical experience along with the available pertinent research were used to review xylazine adulteration of the drug supply and provide guidance on the care of patients exposed to xylazine. This review discusses xylazine pharmacology, animal and human clinical effects, and what is known to date about care of patients experiencing acute overdose, xylazine-fentanyl withdrawal, and xylazine-associated wounds.

Xylazine in the drug supply: Emerging threats and lessons learned in areas with high levels of adulteration

BACKGROUND

Xylazine, a sedative analgesic drug approved as an animal tranquilizer but not for human use, has become an adulterant in the illicit opioid marketplace in North America. Recently declared an emerging health threat in the U.S., the prevalence of xylazine in overdose deaths increased 5.5-fold between 2019 and 2021. More information is needed about the impact of xylazine on opioid users and harm reduction service providers.

METHODS

The impact of xylazine adulteration was triangulated through examination of (1) opioid overdose fatalities in Connecticut between 2017 and 2021 reported by the Office of the Chief Medical Examiner data, (2) a convenience survey of people in Connecticut who use drugs (PWUD) regarding their knowledge of and attitude about the local illicit drug supply, and (3) semi-structured interviews of harm reduction service providers in Connecticut and Philadelphia in response to prompts on the impacts of and responses to xylazine adulteration.

RESULTS

The presence of fentanyl or its analogues in fatal opioid overdoses was a statistically significant predictor of xylazine presence [OR = 25.0, 95%CI (10.7,81.1)] as was being Hispanic [OR = 1.36, 95%CI (1.03,1.77)]. A survey of people who used drugs revealed that 43% (n = 286) were concerned that the drug supply was always unpredictable. Three-quarters of respondents were aware of xylazine and two-thirds would use a xylazine test strip if one was available. Respondents who identified as White, Hispanic were most likely to be aware of xylazine, to have used a fentanyl test strip, and to be interested in a xylazine test strip. Respondents who injected drugs were 3.6-fold more likely than those who did not inject to endorse an interest in a xylazine test strip. Harm reduction service providers were cognizant of a range of problems surrounding the use and injection of xylazine. Although they reported implementing practices to better respond to xylazine harms, they recognized the absence of solutions to many of the problems encountered.

CONCLUSION

The prevalence of xylazine has expanded, especially in combination with fentanyl. Harm reduction education efforts with fidelity to best practices have emerged, but the harms persist and community prevention needs are largely unmet.

Public health impact and harm reduction implications of xylazine-involved overdoses: a narrative review

INTRODUCTION

Xylazine, an α2-adrenoceptor agonist sedative commonly used in veterinary medicine, is not approved for human use. Nevertheless, xylazine-involved overdose rates have surged in recent years, fueled by an increasingly toxic and synthetic illicit drug supply in North America.

METHODS

This narrative review assessed major epidemiological trends in xylazine-involved overdoses in North America, aiming to identify harm reduction priorities. A literature search was conducted using four bibliographic databases (PubMed, Scopus, Embase, and ScienceDirect) and three preprint servers (medRxiv, bioRxiv, and Europe PMC) on May 28, 2023, to capture articles related to combinations of keywords such as "xylazine", "opioid", and "harm reduction".

RESULTS

Xylazine emerged as an adulterant in Puerto Rico in 2001, likely diverted from veterinary supplies. By the mid-2010s, it began proliferating across unregulated US drug markets, often contemporaneously with illicitly manufactured fentanyl (IMF), displaying characteristics of a syndemic. Initially concentrated in Northeastern regions (e.g., Philadelphia, Connecticut, Maryland), xylazine-involved overdoses later extended to the Rust Belt, Southern, and Western regions of the USA in the late 2010s and early 2020s. During this time, xylazine-involved overdoses also surged in Canada, particularly in Western provinces (British Columbia and Alberta) and Ontario with established IMF-dominated unregulated drug markets.

DISCUSSION

Over the past two decades, xylazine-involved overdoses have been rapidly rising in North America and exhibit few signs of slowing down, representing a serious public health epidemic. Numerous factors may have contributed to this, including limited epidemiological surveillance and drug checking for xylazine and emerging novel adulterants; further, barriers to comprehensive, trauma-informed, non-stigmatizing treatment and social services have also exacerbated this issue. While several epidemiological and ethnographic studies have assessed these factors in the USA, limited evidence is available in Canada where xylazine emerged more recently. This underscores the need for additional research and harm reduction measures.

CONCLUSION

Harm reduction-informed public health guidelines and programs are urgently needed to promote a safer supply, strengthen the healthcare system capacity to prevent and respond to xylazine-involved overdoses, and address social and structural disparities in health outcomes.

Xylazine-involved fatal overdoses and localized geographic clustering: Cook County, IL, 2019-2022

BACKGROUND

Xylazine, a veterinary analgesic sedative, is circulating in the illicit drug markets of at least 23 states including Illinois. We conducted a geographic analysis to better identify the spatial distribution of xylazine-involved fatal overdoses in Cook County, IL.

METHODS

Cook County Medical Examiner Office's (CCMEO) publicly available data was used to identify xylazine-involved fatal overdoses from January 1, 2019, to June 30, 2022. Xylazine-positive (cases) to xylazine-negative groups with drug mixtures involving fentanyl, alcohol and stimulants (controls) were matched on age, race, sex, and year of death. Ripley's K-function was used to examine the likelihood of case clustering compared to controls with the Bernoulli spatial scan deployed to identify specific geographic clusters.

RESULTS

Almost all (94.4%) xylazine-positive overdoses contained fentanyl. Using coordinate-based matching, we found that approximately 3% of xylazine overdose incidents were co-located with other overdoses. Xylazine cases clustered to from 0 to 16.1 miles (max=10.6 miles). Results of the Bernoulli spatial scan varied by control group with two high-risk clusters found relative to alcohol and stimulants and a low-risk cluster relative to fentanyl. Differences in co-occurring drugs were found between xylazine and fentanyl groups like the absolute number of drugs (4.6v 3.4, p<0.0001) and fentanyl analog types.

CONCLUSIONS

Xylazine fatal overdose incident locations exhibited localized clustering relative to fentanyl overdoses but clusters were not precisely detected at these scales. Even so, our results, especially relative to repeat overdose micro "hot spots", offer insight on targeting harm reduction and other services at the neighborhood-level.

The New Stealth Drug on the Street: A Narrative Review of Xylazine as a Street Drug

Xylazine is an alpha-adrenergic receptor agonist approved for use only in animals with a prescription from a veterinarian. It is a powerful sedative that is slowly infiltrating the recreational street drug scene and is often used by polysubstance abusers. Known as "tranq," it can be fatal, and xylazine-induced toxicity cannot be reversed with naloxone or nalmefene. Due to its vasoconstrictive effects, chronic use of xylazine is associated with necrotic skin lesions and general deterioration of health. Since xylazine is not approved for human use and is not scheduled as a controlled substance, there are no human studies to provide evidence of drug-drug interactions, lethal doses, or reversal protocols. Xylazine is available online without a prescription. Street drug users may take xylazine knowingly or unknowingly, as it is often combined with other illicit substances such as fentanyl. There are no rapid tests for xylazine, although there are specialty tests that can be ordered. Xylazine represents a major threat to street drug users and another challenge to emergency healthcare workers, first responders, and others who care for those who have taken this "new" street drug.

The first drug-related death associated with xylazine use in the UK and Europe

BACKGROUND AND AIMS

On November 8th^, 2022, the United States Food and Drug Administration (FDA) issued a statement alerting healthcare professionals to the increasing prevalence of xylazine in illicit drug overdoses in the country. Xylazine is a veterinary medicine with sedative, analgesic and muscle relaxant properties that is used as a heroin/fentanyl adulterant on the illicit drug market in North America. Here we report the first drug-related death associated with xylazine in the United Kingdom.

METHODS

The National Programme on Substance Abuse Deaths (NPSAD) receives reports on drug-related deaths from coroners In England, Wales and Northern Ireland on a voluntary basis. The NPSAD was searched for cases with xylazine detections in cases received by December 31, 2022.

RESULTS

One drug-related death associated with xylazine use was reported to NPSAD by December 31, 2022. The deceased was a 43-year-old male who was found dead at home with drug paraphernalia located at the property in May 2022. The post-mortem examination identified recent puncture wounds to the groin. Coronial documentation reports that the deceased had a history of illicit drug use. A number of drugs were detected by post-mortem toxicology and xylazine was implicated in death alongside heroin, fentanyl and cocaine.

CONCLUSIONS

To the best of our knowledge, this is the first death associated with xylazine use reported in the UK, and even Europe, and indicates the entry of xylazine into the UK drug supply. This report highlights the importance of monitoring changes in illicit drug markets and the emergence of new drugs.

Opioid overdoses involving xylazine in emergency department patients: a multicenter study

INTRODUCTION

Illicit opioids, consisting largely of fentanyl, novel synthetic opioids, and adulterants, are the primary cause of drug overdose fatality in the United States. Xylazine, an alpha-2 adrenergic agonist and veterinary tranquilizer, is being increasingly detected among decedents following illicit opioid overdose. Clinical outcomes in non-fatal overdose involving xylazine are unexplored. Therefore, among emergency department patients with illicit opioid overdose, we evaluated clinical outcome differences for patients with and without xylazine exposures.

METHODS

This multicenter, prospective cohort study enrolled adult patients with opioid overdose who presented to one of nine United States emergency departments between 21 September 2020, and 17 August 2021. Patients with opioid overdose were screened and included if they tested positive for an illicit opioid (heroin, fentanyl, fentanyl analog, or novel synthetic opioid) or xylazine. Patient serum was analyzed via liquid chromatography quadrupole time-of-flight mass spectroscopy to detect current illicit opioids, novel synthetic opioids, xylazine and adulterants. Overdose severity surrogate outcomes were: (a) cardiac arrest requiring cardiopulmonary resuscitation (primary); and (b) coma within 4 h of arrival (secondary).

RESULTS

Three hundred and twenty-one patients met inclusion criteria: 90 tested positive for xylazine and 231 were negative. The primary outcome occurred in 37 patients, and the secondary outcome occurred in 111 patients. Using multivariable regression analysis, patients positive for xylazine had significantly lower adjusted odds of cardiac arrest (adjusted OR 0.30, 95% CI 0.10-0.92) and coma (adjusted OR 0.52, 95% CI 0.29-0.94).

CONCLUSIONS

In this large multicenter cohort, cardiac arrest and coma in emergency department patients with illicit opioid overdose were significantly less severe in those testing positive for xylazine.

Xylazine Complicating Opioid Ingestions in Young Children

The authors of this report present 3 cases of synthetic opioid intoxication complicated by the concomitant presence of the additive xylazine, a nonopioid sedative analgesic and muscle relaxant used in veterinary medicine that potentiates respiratory depression associated with the opioid toxidrome. Three exposed children presented with severe signs and symptoms, 2 of whom experienced cardiac arrest, a need for continuous naloxone infusion or multiple naloxone doses, or mechanical ventilation to treat respiratory failure after their exposures. Additives were detected in urine studies only through the performance of specialized toxicology testing. Detection of xylazine among adult overdose deaths has recently increased sharply, particularly across the northeastern United States. Adulteration by xylazine is an emerging public health threat nationally. Our report reveals that pediatricians should be aware of sentinel drug trends among adults, including the emerging types of illicit, synthetic, or counterfeit formulations of recreational substances, because children may be harmed because of accidental or intentional exposure. Children exposed to dangerous substances also need child protection services that may entail safe relocation outside of the home and the referral of affected caregivers to necessary substance use treatment services. Given epidemic drug use among adults, pediatricians should be competent to recognize common toxidromes and be aware that signs and symptoms may be potentiated by synergistic novel additives or polysubstance exposures. Importantly, standard urine drug screens may not detect synthetic opioid derivatives or contributing additives, so that diagnosis will require specialized toxicology testing.

Potency-Enhancing Synthetics in the Drug Overdose Epidemic: Xylazine ("Tranq"), Fentanyl, Methamphetamine, and the Displacement of Heroin in Philadelphia and Tijuana

Multiple transformations-referred to as "waves" in a panoply of recent public health and law enforcement publications-have rendered North American drug markets increasingly toxic since the early 2010s. The introduction of exceptionally potent synthetic sedatives and stimulants is initiating a new generation of drug injectors into co-use of opioids and methamphetamine, catapulting rates of deadly overdoses and infectious diseases. Drawing on extensive participant-observation research in Philadelphia (2007-present) and Tijuana (2018-present), we document the experience of street-based drug users across these two North American cities to focus on regional shifts in narcotics supplies and endpoint user preferences. We link the dramatic proliferation of fentanyl, methamphetamine, xylazine, and Mexican white powder heroin to: 1) pre-existing drug supply networks on the western and eastern coasts of the North American subcontinent; 2) material characteristics of local heroin supplies in pre-fentanyl opiate markets (Mexican black tar vs. Colombian off-white powder heroin); and 3) racialized repression/incarceration of drug sellers and users on both sides of the Mexico-US border. The article combines economic and medical anthropology to develop an ethnographically-informed political economy approach to an urgent public health challenge among street-based drug users with the highest overdose mortality rates in the US Northeastern Rust Belt and the Northwestern Mexican borderland metroplex anchored by Tijuana. It foregrounds street users' experiences in real time amidst rapidly shifting narcotics supply chains, linking market-driven logics of profit-seeking to the war on drugs' prohibitionist policy context, highlighting increasing toxic impacts on vulnerable sectors across regions.

Xylazine and Overdoses: Trends, Concerns, and Recommendations

Xylazine is a nonopioid veterinary anesthetic and sedative that is increasingly detected in the illicit drug supply in the United States. Data indicate a striking prevalence of xylazine among opioid-involved overdose deaths. The emergence of xylazine in the illicit drug supply poses many unknowns and potential risks for people who use drugs. The public health system needs to respond by increasing testing to determine the prevalence of xylazine, identifying its potential toxicity at various exposure levels, and taking mitigating action to prevent harms. Currently, there is little testing capable of identifying xylazine in drug supplies, which limits the possibility of public health intervention, implementation of harm reduction strategies, or development of novel treatment strategies. (Am J Public Health. 2022;112(8):1212-1216. https://doi.org/10.2105/AJPH.2022.306881).

Nanocoral-like Polyaniline-Modified Graphene-Based Electrochemical Paper-Based Analytical Device for a Portable Electrochemical Sensor for Xylazine Detection

A portable electrochemical device for xylazine detection is presented for the first time. An electrochemical paper-based analytical device (ePAD) was integrated with a smartphone. The fabrication of the ePAD involved wax printing, low-tack transfer tape, and cutting and screen-printing techniques. Graphene ink was coated on the substrate and modified with nanocoral-like polyaniline, providing an electron transfer medium with a larger effective surface area that promoted charge transfer. The conductive ink on the ePAD presented a thickness of 25.0 ± 0.9 μm for an effective surface area of 0.374 cm². This sensor was then tested directly on xylazine using differential pulse voltammetry. Two linear responses were obtained: from 0.2 to 5 μg mL^-1 and from 5 to 100 μg mL^-1. The detection limit was 0.06 μg mL^-1. Reproducibility was tested on 10 preparations. The relative standard deviation was less than 5%. The applicability of the sensor was evaluated with beverage samples spiked with trace xylazine. Recoveries ranged from 84 ± 4 to 105 ± 2%. The developed sensor demonstrated excellent accuracy in the detection of trace xylazine. It would be possible to develop the portable system to detect various illicit drugs to aid forensic investigations.

Xylazine spreads across the US: A growing component of the increasingly synthetic and polysubstance overdose crisis

BACKGROUND

Sharp exacerbations of the US overdose crisis are linked to polysubstance use of synthetic compounds. Xylazine is a veterinary tranquilizer, long noted in the street opioid supply of Puerto Rico, and more recently Philadelphia. Yet its national trends, geographic distribution, and health risks are poorly characterized.

METHODS

In this sequential mixed-methods study, xylazine was increasingly observed by ethnographers in Philadelphia among drug-sellers and people who inject drugs (PWID). Subsequently, we systematically searched for records describing xylazine-present overdose mortality across the US and assessed time trends and overlap with other drugs.

RESULTS

In 10 jurisdictions - representing all four US Census Regions - xylazine was increasingly present in overdose deaths, rising from 0.36% of deaths in 015m 6.7% in 2020. The highest xylazine prevalence data was observed in Philadelphia, (25.8% of deaths), followed by Maryland (19.3%) and Connecticut (10.2%). Illicitly-manufactured-fentanyls were present in 98.4% of xylazine-present-overdose-deaths - suggesting a strong ecological link - as well as cocaine (45.4%), benzodiazepines (28.4%), heroin (23.3%), and alcohol (19.7%). PWID in Philadelphia described xylazine as a sought-after adulterant that lengthens the short duration of fentanyl injections. They also linked it to increased risk of soft tissue infection and naloxone-resistant overdose.

CONCLUSIONS

Xylazine is increasingly present in overdose deaths, linked to the proliferation of illicitly-manufactured-fentanyls. Ethnographic accounts associate it with profound risks for PWID. Nevertheless, many jurisdictions do not routinely test for xylazine, and it is not comprehensively tracked nationally. Further efforts are needed to provide PWID with services that can help minimize additional risks associated with a shifting drug supply.

Xylazine detected in unregulated opioids and drug administration equipment in Toronto, Canada: clinical and social implications

BACKGROUND

The North American opioid overdose crisis is driven in large part by the presence of unknown psychoactive adulterants in the dynamic, unregulated drug supply. We herein report the first detection of the psychoactive veterinary compound xylazine in Toronto, the largest urban center in Canada, by the city's drug checking service.

METHODS

Toronto's Drug Checking Service launched in October 2019. Between then and February 2021, 2263 samples were submitted for analysis. The service is offered voluntarily at harm reduction agencies that include supervised consumption services. Samples were analyzed using gas chromatography-mass spectrometry or liquid chromatography-high resolution mass spectrometry. Targeted and/or untargeted screens for psychoactive substances were undertaken.

RESULTS

In September 2020, xylazine was first detected by Toronto's Drug Checking Service. Among samples analyzed from September 2020 to February 2021 expected to contain fentanyl in isolation (610) or in combination with methamphetamine (16), xylazine was detected in 46 samples (7.2% and 12.5% of samples, respectively). Samples were predominantly drawn from used drug equipment. Three of the samples containing xylazine (6.5%) were associated with an overdose.

CONCLUSION

We present the first detection of xylazine in Toronto, North America's fourth-largest metropolitan area. The increased risk of overdose associated with use of xylazine and its detection within our setting highlights the importance of drug checking services in supporting rapid responses to the emergence of potentially harmful adulterants. These data also highlight the clinical challenges presented by the dynamic nature of unregulated drug markets and the concomitant need to establish regulatory structures to reduce their contribution to overdose morbidity and mortality.

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.

High prevalence of xylazine among fentanyl screen-positive urines from hospitalized patients, Philadelphia, 2021

BACKGROUND

Xylazine is an α-2 adrenoreceptor agonist used as a sedative/analgesic in veterinary medicine. Xylazine is known to be present within the street supply of opiates in urban Philadelphia. Medical staff at our hospital asked if we could test for xylazine in fentanyl screen-positive urine samples. We developed an LC-MS/MS assay for this purpose, and determined prevalence of xylazine among fentanyl screen-positive urine samples at our hospital.

METHODS

The LC-MS/MS assay utilized d5-norfentanyl as internal standard (IS). One hundred microliter samples were extracted with 200 µl of MeOH/IS. LC was performed using a Phenomenex Kinetix C18 column (100 A, 5 µm, 50 × 4.6 mm) at 40 °C. Time-variable mobile phases (A = H2O, 0.1% formic acid; B = MeOH, 0.1% formic acid) were used at a fixed flow rate of 0.5 ml/min. MS/MS used positive electrospray ionization, monitoring m/z transitions of 221 > 164 for xylazine (primary), 221 > 90 for xylazine (qualifier), and 238 > 84 for d5-norfentanyl (IS). Retention time was 3.9 min for both xylazine and IS.

RESULTS

Calibration curve was linear (0-500 ng/ml; r > 0.99). Inter-assay CVs (n = 20) were 5.2% (18 ng/ml) and 6.6% (95 ng/ml). Lower limit of detection was set at 10 ng/ml (CV = 15%). Among 81 urine samples that were screen-positive for fentanyl (Ark Diagnostics immunoassay), 63 (78%) were positive for xylazine (>10 ng/ml).

CONCLUSIONS

By LC-MS/MS, there was high prevalence (78%) of xylazine in fentanyl screen-positive urine samples submitted to the laboratory. Because α-2 adrenoreceptor agonists may be used in treatment of opioid addiction, knowledge of xylazine exposure may be clinically useful to guide patient management.

Xylazine, a Veterinary Tranquilizer, Detected in 42 Accidental Fentanyl Intoxication Deaths

ABSTRACT

Xylazine is an emerging adulterant with fentanyl in fatal drug intoxications, which has public health, safety, and criminal investigative implications. Xylazine is a nonnarcotic sedative used for analgesia and muscle relaxation exclusively in veterinary medicine. Its chemical structure is similar to clonidine and acts as a central α-2 agonist which may cause bradycardia and transient hypertension followed by hypotension. We report the detection of xylazine in 42 deaths in Connecticut from March to August 2019. Xylazine combined with an opioid or stimulant may affect the toxicity of these drugs. Detection of xylazine may help the forensic pathologist distinguish illicit from prescribed fentanyl, and law enforcement agents track the illicit drugs to a specific drug supplier. Because of its lack of response to naloxone, emergency medicine physicians need to be aware of its potential presence as it may affect therapy.

A portable electrochemical sensor for detection of the veterinary drug xylazine in beverage samples

A portable electrochemical sensor was developed to determine xylazine in spiked beverages by adsorptive stripping voltammetry (AdSV). The sensor was based on a graphene nanoplatelets-modified screen-printed carbon electrode (GNPs/SPCE). The electrochemical behavior of xylazine at the GNPs/SPCE was an adsorption-controlled irreversible oxidation reaction. The loading of graphene nanoplatelets (GNPs) on the modified SPCE, electrolyte pH, and AdSV accumulation potential and time were optimized. Under optimal conditions, the GNPs/SPCE provided high sensitivity, linear ranges of 0.4-6.0 mg L^-1 (r = 0.997) and 6.0-80.0 mg L^-1 (r = 0.998) with a detection limit of 0.1 mg L^-1 and a quantitation limit of 0.4 mg L^-1. Repeatability was good. The accuracy of the proposed sensor was investigated by spiking six beverage samples at 1.0, 5.0, and 10.0 mg L^-1. The recoveries from this method ranged from 80.8 ± 0.2-108.1 ± 0.3 %, indicating the good accuracy of the developed sensor. This portable electrochemical sensor can be used to screen for xylazine in beverage samples as evidence in cases of sexual assault or robbery.

Increasing presence of xylazine in heroin and/or fentanyl deaths, Philadelphia, Pennsylvania, 2010-2019

Reports from active drug users state that xylazine, the veterinary tranquilliser, has been increasing in the illicit drug supply in Philadelphia. To describe trends and characteristics of unintentional deaths from heroin and/or fentanyl overdose with xylazine detections occurring in Philadelphia, Pennsylvania, the Philadelphia Department of Public Health analysed data on deaths from unintentional heroin and/or fentanyl overdose from the Philadelphia Medical Examiner's Office over a 10-year period (2010-2019). Xylazine went from being detected in less than 2% cases of fatal heroin and/or fentanyl overdose between 2010 and 2015 to 262 (31%) of the 858 fatal heroin and/or fentanyl overdose cases in 2019. Currently, information is limited on the presence of xylazine in continental United States. Xylazine's association with adverse outcomes in other locations indicates that potential health consequences should also be monitored in the USA. Whenever possible, jurisdictions should consistently test for xylazine.

When "the Cure" Is the Risk: Understanding How Substance Use Affects HIV and HCV in a Layered Risk Environment in San Juan, Puerto Rico

BACKGROUND

Substance use, particularly injection drug use, continues to fuel the HIV/HCV (hepatitis C virus) epidemics in San Juan, Puerto Rico (PR).

AIM

This article examines individual and sociostructural factors that affect HIV/HCV risk among people who use drugs (PWUD) living with or at risk for HIV/HCV in San Juan, PR. Findings were used to inform a community-level intervention to enhance HIV care access and retention for this population.

METHOD

A rapid ethnographic assessment in collaboration with a community-based organization was conducted. Data collection took place between June and December 2013 and included field observations, 49 unstructured interviews with PWUD, and 19 key informant interviews with community stakeholders. Fieldnotes, photographs, and interview transcripts were analyzed for recurrent themes and to address the intervention-planning needs. Study results are presented as fieldnote excerpts, direct quotes from interviews, and photographs.

RESULTS

Findings suggest that PWUD in PR face myriad challenges that affect HIV/HCV risk and hinder linkage to and retention in care. Results describe a layered risk environment where PWUD encounter many barriers to prevention, care, and treatment such as transience, social isolation, stigma, limited housing options, and inadequate medical and substance use disorder treatment services.

DISCUSSION

These observed circumstances provide an empirical basis for the development and evaluation of comprehensive interventions that may serve to reduce barriers to care and link individuals to other supportive services.

CONCLUSION

New approaches and comprehensive interventions are needed to break the structures that perpetuate risk and lack of engagement and retention in HIV care and substance use disorder treatment in San Juan.

Xylazine as a drug of abuse and its effects on the generation of reactive species and DNA damage on human umbilical vein endothelial cells

Human xylazine (XYL) abuse among addicts has received great interest due to its potential toxic effects upon addicts and the need to understand the mechanism of action associated with the potential health effects. XYL is an alpha-2 agonist restricted to veterinarian applications, without human medical applications. Our previous work demonstrated that XYL and its combination with cocaine (COC) and/or 6-monoacetylmorphine (6-MAM) induce cell death through an apoptotic mechanism. The aim of this study was to determine the effect of xylazine on the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as DNA damage on endothelial cell. Human umbilical vein endothelial cells (HUVEC) were treated with XYL (60 μM), COC (160 μM), 6-MAM (160 μM), camptothecin (positive control, 50 μM), XYL/COC (50 μM), XYL/6-MAM (50 μM), and XYL/COC/6-MAM (40 μM) for a period of 24 hours. Generation of intracellular ROS, RNS, and DNA fragmentation were analyzed using a fluorometric assay. Results reveal that XYL and 6-MAM increase levels of ROS; no induction of RNS production was observed. The combination of these drugs shows significant increase in DNA fragmentation in G2/M phase, while XYL, COC, and 6-MAM, without combination, present higher DNA fragmentation in G0/G1 phase. These findings support that these drugs and their combination alter important biochemical events aligned with an apoptotic mechanism of action in HUVEC.

Addressing the HIV/AIDS epidemic among Puerto Rican people who inject drugs: the need for a multiregion approach

High levels of HIV risk behaviors and prevalence have been reported among Puerto Rican people who inject drugs (PRPWID) since early in the HIV epidemic. Advances in HIV prevention and treatment have reduced HIV among people who inject drugs (PWID) in the United States. We examined HIV-related data for PRPWID in Puerto Rico and the US Northeast to assess whether disparities continue. Injection drug use as a risk for HIV is still overrepresented among Puerto Ricans. Lower availability of syringe exchanges, drug abuse treatment, and antiretroviral treatment for PWID in Puerto Rico contribute to higher HIV risk and incidence. These disparities should be addressed by the development of a federally supported Northeast-Puerto Rico collaboration to facilitate and coordinate efforts throughout both regions.

Toxic effects of xylazine on endothelial cells in combination with cocaine and 6-monoacetylmorphine

The use of xylazine as a drug of abuse has emerged worldwide in the last 7 years, including Puerto Rico. Clinical findings reported that xylazine users present greater physiological deterioration, than heroin users. The aim of this study was to assess the xylazine toxicity on endothelial cells, as this is one of the first tissues impact upon administration. Human umbilical vein endothelial cells in culture were treated with xylazine, cocaine, 6-monoacetylmorphine (heroin metabolite) and its combinations, at concentrations of 0.10-400 μM, for periods of 24, 48 and 72 h. IC50 were calculated and the Annexin V assay implemented to determine the cell death mechanism. Results indicated IC50 values at 24h as follow: xylazine 62 μM, cocaine 210 μM, 6-monoacetylmorphine 300 μM. When these drugs were combined the IC50 value was 57 μM. Annexin V results indicated cell death by an apoptosis mechanism in cells treated with xylazine or in combination. Results demonstrated that xylazine use inhibits the endothelial cell proliferation, at lower concentrations than cocaine and 6-monoacetylmorphine. These findings contribute to the understanding of the toxicity mechanisms induced by xylazine on endothelial cells.

Xylazine intoxication in humans and its importance as an emerging adulterant in abused drugs: A comprehensive review of the literature

Xylazine is not a controlled substance; it is marketed as a veterinary drug and used as a sedative, analgesic and muscle relaxant. In humans, it could cause central nervous system depression, respiratory depression, bradycardia, hypotension, and even death. There have been publications of 43 cases of xylazine intoxication in humans, in which 21 (49%) were non-fatal scenarios and 22 (51%) resulted in fatalities. Most of the non-fatal cases required medical intervention. Over recent years xylazine has emerged as an adulterant in recreational drugs, such as heroin or speedball (a cocaine and heroin mixture). From the 43 reported cases, 17 (40%) were associated with the use of xylazine as an adulterant of drugs of abuse. Its chronic use is reported to be associated with physical deterioration and skin ulceration. Literature shows some similar pharmacologic effects between xylazine and heroin in humans. These similar pharmacologic effects may create synergistic toxic effects in humans. Therefore, fatalities among drug users may increase due to the use of xylazine as an adulterant. Xylazine alone has proven harmful to humans and even more when it is combined with drugs of abuse. A comprehensive review of the literature of non-fatal and fatal xylazine intoxication cases including those in which the substance was used as adulterant is presented, in order to increase the awareness in the forensic community, law enforcement, and public health agencies.

Xylazine-induced reduction of tissue sensitivity to insulin leads to acute hyperglycemia in diabetic and normoglycemic monkeys

BACKGROUND

The α2-adrenoceptor agonist xylazine as an anesthetic has been widely used either alone or in combination with other anesthetics, such as ketamine, in veterinary clinic and research. In the last decade xylazine has been used in drug abusers in certain geographic area. This study investigated the effects of xylazine on blood glucose level and insulin secretion in normoglycemic and insulin-dependent diabetic monkeys.

METHODS

Both adult cynomolgus (n = 10) and rhesus (n = 8) monkeys with either sex were used in the study. Xylazine (1-2 mg/kg) was administrated intramuscularly. Blood glucose, insulin, glucagon and glucagon-like peptide 1 in overnight-fasted monkeys were measured immediately before and after xylazine administration. The hyperinsulinemic-euglycemic clamp method was used in the study for assessing the potential mechanism of xylazine-induced hyperglycemia.

RESULTS

Xylazine administration increased the blood glucose levels from 58 ± 3 to 108 ± 12 mg/dL in normoglycemic (n = 5, p < 0.01) and from 158 ± 9 to 221 ± 13 mg/dL in insulin-dependent diabetic (n = 5, p < 0.01) monkeys and was not accompanied by any significant changes in blood insulin, glucagon, and glucagon-like peptide-1. Xylazine-induced hyperglycemia occurred within 10 min and reached the peak at 35 min after injection. Xylazine-induced hyperglycemia declined slowly in diabetic animals. The α2-adrenoceptor antagonist yohimbine was administrated to bring down the elevated glucose level to the pre-xylazine one in 4 out of 5 diabetic animals. To assess the potential mechanism, the hyperinsulinemic-euglycemic clamp was used to maintain a nearly saturated and constant insulin level for minimizing endogenous insulin glucoregulation. Xylazine administration decreased glucose infusion rate, from 14.3 ± 1.4 to 8.3 ± 0.8 mg/min/kg (n = 6, p < 0.01) in normoglycemic rhesus monkeys, which indicates that the glucose metabolic rate (M rate) was decreased by xylazine. In addition, after clamping blood glucose level in a range of 55 to 75 mg/dL for 40 min with constant glucose infusion, xylazine administration still increased blood glucose concentration.

CONCLUSIONS

We conclude that xylazine administration induces hyperglycemia in normoglycemic and insulin-dependent diabetic monkeys potentially via stimulation of α2-adrenoceptors and then reducing tissue sensitivity to insulin and glucose uptake.