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.

Qualitative and quantitative determination of xylazine in oral fluid.

Xylazine has emerged in recent years as a dangerous adulterant in illicit fentanyl use, and methods for the detection of xylazine in toxicology panels are still lagging. We developed methods for the screening and quantitation of xylazine in oral fluid (OF), a popular testing medium due to its ease of collection and reflection of presence in blood for many classes of drugs. Enzyme-linked immunosorbent assays were employed for the rapid screening of xylazine directly from the collection device buffer with a cutoff of 1 ng/mL. Solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry facilitated the confirmation and quantification of xylazine as low as 0.1 ng/mL and a dynamic range of 0.1-25 ng/mL. Selectivity, ionization suppression, processed sample stability, and dilution effect were also assessed. The method was validated through the American National Standards Institute/American Academy of Forensic Sciences Standards Board (ANSI/ASB) Standard 036, first edition from 2019, and found to be accurate, precise, and robust. Living human subject OF samples collected within substance use disorder and therapeutic drug monitoring clinics received between September 2023 and January 2024, with the specific request to test for xylazine (n = 57), were screened. Presumptive positive samples were confirmed using the validated method. Xylazine confirmed living human subject OF sample concentrations ranged from 1.2 to 23.3 ng/mL.

Reported Xylazine Use Among Adults Aged ≥18 Years Evaluated for Substance Use Treatment - United States, July 2022-September 2023.

Xylazine has been increasingly detected in illegally manufactured fentanyl (IMF) products and overdose deaths in the United States; most xylazine-involved overdose deaths involve IMF. A convenience sample of U.S. adults aged ≥18 years was identified from those evaluated for substance use treatment during July 2022-September 2023. Data were collected using the Addiction Severity Index-Multimedia Version clinical assessment tool. Among 43,947 adults, 6,415 (14.6%) reported IMF or heroin as their primary lifetime substance-use problem; 5,344 (12.2%) reported recent (i.e., past-30-day) IMF or heroin use. Among adults reporting IMF or heroin as their primary lifetime substance-use problem, 817 (12.7%) reported ever using xylazine. Among adults reporting recent IMF or heroin use, 443 (8.3%) reported recent xylazine use. Among adults reporting IMF or heroin use recently or as their primary lifetime substance-use problem, those reporting xylazine use reported a median of two past nonfatal overdoses from any drug compared with a median of one overdose among those who did not report xylazine use; as well, higher percentages of persons who reported xylazine use reported other recent substance use and polysubstance use. Provision of nonjudgmental care and services, including naloxone, wound care, and linkage to and retention of persons in effective substance use treatment, might reduce harms including overdose among persons reporting xylazine use.

A content analysis of legal policy responses to xylazine in the illicit drug supply in the United States.

BACKGROUND: Xylazine is a veterinary sedative that is quickly spreading in the U.S. illicit drug supply and is increasingly associated with fatal overdoses and severe wounds. In response, xylazine has been deemed an emerging public health threat and several policy initiatives have been introduced to combat its spread and negative broad health impact. We aimed to synthesize trends in all-time U.S. policy responses to xylazine in the drug supply. METHODS: In April 2024, we systematically identified and categorized proposed and enacted policy initiatives that related to human xylazine consumption by searching LexisNexis and Thomas Reuters Westlaw legal databases. RESULTS: Of 58 unique policy initiatives, most were introduced in 2023 (n = 37/58, 64 %) and concentrated in Northeastern states. Penalties for xylazine possession, often tied to state drug scheduling changes, were the most common provision (n = 34/58; 59 %) and Schedule III was the most frequently proposed scheduling level (n = 17/30; 57 %). Other provisions included proposals to enhance: test strip access (n = 11/58; 19 %), public awareness and education (n = 3/58; 5 %), xylazine-specific research (n = 4/58; 7 %), and surveillance (n = 8/58; 14 %). CONCLUSION: U.S. state and federal policy responses to xylazine grew rapidly in 2023, were most concentrated in states affected most by xylazine, and scheduling was the most commonly proposed policy approach. Research measuring policy effects should be prioritized as policies are implemented.

"Tranq-dope": The first fatal intoxication due to xylazine-adulterated heroin in Italy.

BACKGROUND AND AIMS: The number of xylazine-involved overdose deaths tremendously increased from 2019 onwards in the US. This is due to the "tranq-dope" trend consisting in mixing opioids with the sedative to reduce drug manufacturing costs and enhance their effects. In this study, we report the first fatality involving xylazine-adulterated heroin in the EU. MATERIALS AND METHODS: The subject was a 33-year-old Caucasian male with a documented history of drug abuse who was found dead in a public area with puncture marks at the elbow. Peripheral blood and urine were collected at the autopsy and analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS) after protein precipitation. RESULTS: 6-Monoacetylmorphine, total/free morphine, and codeine blood concentrations of 20.3, 236/105, and 38.3 ng/mL, respectively, indicated recent heroin consumption. Methadone blood concentration was below 10 ng/mL. Alprazolam, nordiazepam, and flurazepam blood concentrations were 23.9, 61.4, and 55.0 ng/mL, respectively. Benzoylecgonine blood concentration was below 5 ng/mL. Xylazine blood and urine concentrations were 105 and 72.6 ng/mL, respectively. CONCLUSION: The combination of central nervous system depressants, i.e., opioids, benzodiazepines, and xylazine, was the principal cause of death by cardiorespiratory failure. The case was promptly reported to the UE Early Warning System on drugs.

Rapid differentiation of xylazine metabolites using SLIM IM-MS.

Xylazine represents an increased threat to the recreational drug market. In this study, we present a rapid strategy for identifying xylazine and differentiating its common isomeric metabolites using Structures for Lossless Ion Manipulations (SLIM) ion mobility coupled to high-resolution/tandem mass spectrometry (IM-HRMS/MS). Chemical derivatization using dansyl chloride also assisted with separations and led to identification of resolvable reaction product atropisomers.

TILETAMINE-ZOLAZEPAM-XYLAZINE ANESTHESIA IN EX SITU BLACK-HANDED SPIDER MONKEYS (ATELES GEOFFROYI SSP.).

Black-handed spider monkeys (Ateles geoffroyi ssp.) are endangered in Mexico. Safe anesthetic protocols are important for in situ and ex situ conservation problems. Such protocols are scarce in the literature; nor have safety and physiologic responses been reported. High doses and volume are a counter side for field immobilizations. We tested an anesthetic protocol with a combination of tiletamine-zolazepam (5 mg/kg) plus xylazine (1 mg/kg) in 14 black-handed spider monkeys under human care from two facilities in Mexico. Physiological parameters such as HR, RR, T, SPO2, systolic arterial pressure (), diastolic arterial pressure (DAP), and median arterial pressure (MAP) were obtained. HR and RR decreased over time, but T increased significantly during the anesthetic time for the whole group; RR and T decreased for juveniles only. Variation between individuals was observed for HR, RR, and DAP. Volume reduction of drugs was achieved compared to previously reported anesthesia protocols. Induction time was fast (6.2 ± 10.4 min) and no tail prehension was seen. Recovery was prolonged (mean and SD). Physiologic parameters remained stable throughout. The protocol proved to be safe for the chemical immobilization of black-handed spider monkeys.

O-GlcNAcylation levels remain stable regardless of the anaesthesia in healthy rats.

Anaesthetics are used daily in human and veterinary medicine as well as in scientific research. Anaesthetics have an impact on cell homeostasis especially through modulation of protein post-translational modifications. O-GlcNAcylation, a ubiquitous post-translational modification, plays a role in many biological processes. The aims of this study were to evaluate whether (1) anaesthesia influences O-GlcNAcylation and (2) its stimulation affects physiological parameters. Male Wistar rats (n = 38) were anaesthetized with ketamine-xylazine or isoflurane. They randomly received either an intravenous injection of Ringer's lactate or NButGT (10mg/kg) in order to increase O-GlcNAcylation levels. One hour after induction of anaesthesia, haemodynamic parameters and plasmatic markers were evaluated. Heart, brain and lungs were harvested and O-GlcNAcylation levels and O-GlcNAc-related enzymes were evaluated by western blot. Cardiac and pulmonary O-GlcNAcylation levels and cardiac, cerebral and pulmonary O-GlcNAc associated enzyme expression were not impacted with anaesthesia. Compared with ketamine-xylazine, isoflurane had a lower impact on blood pressure, heart rate and glycaemia. Pharmacological stimulation of O-GlcNAcylation by NButGT did not affect the physiological parameters. This study offers unprecedented insights into the regulation of O-GlcNAcylation and O-GlcNAc related enzymes during anaesthesia. Pharmacological stimulation of O-GlcNAcylation over a 1-h period did not disrupt the physiological balance in healthy anaesthetized rats.

Cardiopulmonary function, anesthetic effects, quality of arousal, hematology, and blood biochemistry during continuous intravenous infusion of a combination solution of xylazine, butorphanol, and propofol in calves.

General anesthesia in calves is easier to perform under field conditions, total intravenous anesthesia (TIVA) than using inhalation anesthesia. In the present study, cardiopulmonary function, anesthetic effects, quality of arousal, hematology, and blood biochemistry were assessed during continuous infusion of a combination solution of 0.01% xylazine, 0.001% butorphanol, and 0.2% propofol (XBP) at doses of 6 (G6; 10 µg/kg/min xylazine, 1 µg/kg/min butorphanol, 200 µg/kg/min propofol) and 9 mL/kg/h (G9; 15 µg/kg/min xylazine, 1.5 µg/kg/min butorphanol 300 µg/kg/min propofol). For both groups, five castrated Holstein calves received intravenous injections of xylazine (0.2 mg/kg) and propofol (2 mg/kg), followed by a continuous infusion of XBP for 60 min to maintain anesthesia. Respiratory management consisted of tracheal intubation followed by spontaneous inhalation of pure oxygen. Cardiopulmonary, anesthesia, hematology, and blood biochemistry variables were assessed at rest (baseline) and every 5 or 15 min after the start of the XBP infusion. Quality of arousal was assessed based on the swallowing reflex recovery time from the stop of XBP infusion, and the sternal position time and standing time after atipamezole administration. XBP produced adequate sedation, analgesia, and muscle relaxation in all calves and maintained stable anesthesia for 60 min. As XBP infusion time passed, rectal temperature and heart rate became lower, and mean arterial blood pressure increased. In both groups, hematologic and blood biochemical effects were mild. The quality of arousal was not different, and all calves were standing. The results of the present study suggested that XBP is useful for TIVA in calves.

Evaluation of the ARK Diagnostics immunoassay for qualitative detection of xylazine in urine.

Xylazine exposure is common in some US cities, but a commercial assay for routine laboratory testing for xylazine is not currently available. We evaluated a pre-release version of the ARK Diagnostics immunoassay for qualitative detection of xylazine/4-hydroxyxylazine in urine. Studies were conducted using either the semi-quantitative assay application (A. Roche Cobas 503 analyzer) or the qualitative assay application (B. Beckman Coulter AU480 analyzer). Study specimens consisted of deidentified patient urine samples submitted for routine drugs-of-abuse testing. Measurements of xylazine (X) were performed by LC-MS-MS to obtain X-NEGATIVE (X <10 ng/mL) and X-POSITIVE (X ≥10 ng/mL). The semi-quantitative ARK assay was calibrated with a 10 ng/mL cutoff for ARK-POSITVE. For (A): among 74 X-POSITIVE samples, there was 1 ARK-NEGATIVE result (false-negative rate = 1.4%); among 78 X-NEGATIVE samples by LC-MS-MS, there were 0% ARK-POSITIVE results (false-positive rate = 0%). For (B), among 74 X-POSITIVE samples, there were 0 ARK-NEGATIVE results (false-negative rate = 0%); among 78 X-NEGATIVE samples there was 1 ARK-POSITIVE sample (false-positive rate = 1.3%). Common sources of interferences were investigated without evidence of interference. The ARK xylazine/4-OH-xylazine immunoassay was found to be suitable for routine use in screening patient urine samples for presence of xylazine >10 ng/mL.

Classics in Chemical Neuroscience: Xylazine.

Xylazine (also known as "tranq") is a potent nonopioid veterinary sedative that has recently experienced a surge in use as a drug adulterant, most often combined with illicitly manufactured fentanyl. This combination may heighten the risk of fatal overdose. Xylazine has no known antidote approved for use in humans, and age-adjusted overdose deaths involving xylazine were 35 times higher in 2021 than 2018. In April 2023, the Biden Administration declared xylazine-laced fentanyl an emerging drug threat in the United States. In 2022, the Drug Enforcement Agency (DEA) reported nearly a quarter of seized fentanyl powder contained xylazine. This dramatic increase in prevalence has solidified the status of xylazine as an emerging drug of abuse and an evolving threat to public health. The following narrative review outlines the synthesis, pharmacokinetics, pharmacodynamics, and adverse effects of xylazine, as well as the role it may play in the ongoing opioid epidemic.

Evaluation of a hapten conjugate vaccine against the "zombie drug" xylazine.

Xylazine has emerged as a primary adulterant in fentanyl, exacerbating the complexity of the opioid crisis. Yet, there is no approved drug that can reverse xylazine's pathophysiology. As a prelude to monoclonal antibodies being assessed as a viable therapeutic, a vaccine inquiry was conducted evaluating the immune response in reversing xylazine induced behavior effects.

Xylazine does not enhance fentanyl reinforcement in rats: A behavioral economic analysis.

The adulteration of illicit fentanyl with the alpha-2 agonist xylazine has been designated an emerging public health threat. The clinical rationale for combining fentanyl with xylazine is currently unclear, and the inability to study fentanyl/xylazine interactions in humans warrants the need for preclinical research. We studied fentanyl and xylazine pharmacodynamic and pharmacokinetic interactions in male and female rats using drug self-administration behavioral economic methods. Fentanyl, but not xylazine, functioned as a reinforcer under both fixed-ratio and progressive-ratio drug self-administration procedures. Xylazine combined with fentanyl at three fixed dose-proportion mixtures did not significantly alter fentanyl reinforcement as measured using behavioral economic analyses. Xylazine produced a proportion-dependent decrease in the behavioral economic Q0 endpoint compared to fentanyl alone. However, xylazine did not significantly alter fentanyl self-administration at FR1. Fentanyl and xylazine co-administration did not result in changes to pharmacokinetic endpoints. The present results demonstrate that xylazine does not enhance the addictive effects of fentanyl or alter fentanyl plasma concentrations. The premise for why illicitly manufacture fentanyl has been adulterated with xylazine remains to be determined.

Substance use patterns, sociodemographics, and health profiles of harm reduction service recipients in Burlington, Vermont.

BACKGROUND: Understanding current substance use practices is critical to reduce and prevent overdose deaths among individuals at increased risk including persons who use and inject drugs. Because individuals participating in harm reduction and syringe service programs are actively using drugs and vary in treatment participation, information on their current drug use and preferred drugs provides a unique window into the drug use ecology of communities that can inform future intervention services and treatment provision. METHODS: Between March and June 2023, 150 participants in a harm reduction program in Burlington, Vermont completed a survey examining sociodemographics; treatment and medication for opioid use disorder (MOUD) status; substance use; injection information; overdose information; and mental health, medical, and health information. Descriptive analyses assessed overall findings. Comparisons between primary drug subgroups (stimulants, opioids, stimulants-opioids) of past-three-month drug use and treatment participation were analyzed using chi-square and Fisher's exact test. RESULTS: Most participants reported being unhoused or unstable housing (80.7%) and unemployed (64.0%) or on disability (21.3%). The drug with the greatest proportion of participants reporting past three-month use was crack cocaine (83.3%). Fentanyl use was reported by 69.3% of participants and xylazine by 38.0% of participants. High rates of stimulant use were reported across all participants independent of whether stimulants were a participant's primary drug. Fentanyl, heroin, and xylazine use was less common in the stimulants subgroup compared to opioid-containing subgroups (p < .001). Current- and past-year MOUD treatment was reported by 58.0% and 77.3% of participants. Emergency rooms were the most common past-year medical treatment location (48.7%; M = 2.72 visits). CONCLUSIONS: Findings indicate high rates of polysubstance use and the underrecognized effects of stimulant use among people who use drugs-including its notable and increasing role in drug-overdose deaths. Crack cocaine was the most used stimulant, a geographical difference from much of the US where methamphetamine is most common. With the increasing prevalence of fentanyl-adulterated stimulants and differences in opioid use observed between subgroups, these findings highlight the importance and necessity of harm reduction interventions (e.g., drug checking services, fentanyl test strips) and effective treatment for individuals using stimulants alongside MOUD treatment.

Broad evidence of xylazine in the UK illicit drug market beyond heroin supplies: Triangulating from toxicology, drug-testing and law enforcement.

BACKGROUND AND AIMS: Xylazine is a non-opioid sedative which has spread rapidly throughout the US illicit drug supply. This study aimed to describe the spread of xylazine throughout the UK illicit drug supply. METHODS: Xylazine detections in human biological samples were collated from toxicology laboratories operating in the United Kingdom with the date, location, case type, xylazine concentration and co-detected drugs (with quantifications where performed) detailed, where permitted, by the corresponding coroner. Drug-testing cases positive for xylazine were collated from the Welsh Emerging Drugs and Identification of Novel Substances (WEDINOS) drug-testing postal service with the date, location, purchase intent and co-detected drugs detailed. Drug seizures made by UK law enforcement were communicated by the Office for Health Improvement and Disparities with the date and location detailed. RESULTS: By the end of August 2023, xylazine was detected in 35 cases from throughout toxicology, drug-testing and drug seizure sources covering England, Scotland and Wales. There were no cases reported from Northern Ireland. Xylazine was detected in biological samples from 16 people. In most cases where full toxicology results were provided, xylazine was detected with heroin and/or a strong opioid (n = nine of 11), but this polydrug use pattern was not evident in all cases (n = two of 11), suggesting a wider circulation of xylazine in the UK illicit drug market beyond heroin supplies. Evidence from WEDINOS supports this claim, as all 14 drug samples (100%) submitted from across the UK contained xylazine; however, in none of these cases was heroin the purchase intent but rather counterfeit prescription medication tablets (n = 11 of 14), tetrahydrocannabinol (THC) vapes (n = two of 14) or white powder (n = one of 14). Additional evidence for the spread of illicit xylazine comes from five drug seizures made by law enforcement. CONCLUSIONS: Xylazine has penetrated the UK illicit drug market and is not limited to heroin supplies.