Introduction Xylazine, an α2-adrenergic agonist used as a veterinary sedative, has emerged as an adulterant of illicit opioids, contributing to fatal overdoses in North America and has recently been detected in Europe. In France, despite alarmist media reports, data on xylazine exposures are scarce. Methods We retrospectively reviewed intentional xylazine exposures reported to the eight French poison control centers from January 2010 to December 2024. Cases were extracted from the French National Database of Poisonings. Inclusion required intentional use; severity was assessed using the Poison Severity Score. Results Nineteen intentional exposures were identified: seventeen in the context of a suicide attempt, one homicidal, and one recreational. Mean age was 36.4 years; sex ratio 2.6 (male/female). For the cases occurring in the context of a suicide attempt, eleven involved xylazine alone, and six in combination with other drugs (mainly ketamine or fentanyl). Three fatalities occurred (16%), and six patients developed severe clinical features (Poisoning Severity Score 3), including coma, bradycardia, and hypotension. The single recreational case involved a fentanyl/xylazine mixture with full recovery. Discussion Over a 14-year period, intentional xylazine poisonings reported to French Poison Control Centers were uncommon, mainly occurring in the context of a suicide attempt, and often linked to occupational access to veterinary sedatives. These data do not support community or recreational spread. Nonetheless, observed cases confirm xylazine’s life-threatening potential. Conclusion This retrospective analysis highlights the rarity of reported xylazine exposures in French poison centre data, strengthened toxicological surveillance and coordination between Poison Control Center and drug-checking networks are needed to detect any shift toward broader use and guide prevention efforts.

Although buprenorphine-based opioid agonist maintenance treatment (OAMT) is effective, logistical, economic and stigma-related barriers limit access. Telemedicine-Assisted Buprenorphine Induction (TABI) may address these barriers. This study evaluated the non-inferiority of TABI compared with the Standard of Care (SoC) for buprenorphine induction. Open-label, two-arm, randomized controlled non-inferiority trial. The induction period lasted 7days, after which all participants continued buprenorphine-based OAMT as routine care. Follow-up assessments were done at one week and one month. Addiction treatment center, Chandigarh, India. Adults with opioid use disorder (OUD) meeting ICD-11 (International Classification of Diseases, 11th Revision) criteria, recruited between December 2023 and August 2024. A total of 138 participants were randomized (SoC = 70; TABI = 68). The mean age of participants was 28.2years. Most participants were male (98.55%). SoC involved supervised in-person buprenorphine induction for three days. TABI consisted of in-person induction on Day 1, followed by telemedicine-based follow-ups for Days 2-6. In-person review on Day 7 in both arms. Primary outcome: treatment retention at one week, using a 15% non-inferiority margin. abstinence from illicit opioids, withdrawal symptoms, cravings, quality of life, satisfaction, therapeutic alliance and medication adherence. The one-week retention rate was 75.71% in the SoC group and 82.35% in the TABI group, with an absolute difference of 6.64% [95% confidence interval (CI) = -6.88% to 20.16%]. The lower limit of the 95% confidence interval for the difference (-6.88%) is above the pre-specified non-inferiority margin, confirming the non-inferiority of TABI compared with SoC. Both groups showed statistically significant improvements in withdrawal symptoms, cravings and quality of life over time, with no statistically significant group differences. Patient satisfaction, therapeutic relationships, adherence and side effects were comparable between groups. This randomized controlled trial found that telemedicine-assisted buprenorphine induction was non-inferior to standard care for one-week retention in treatment among adults with opioid use disorder. As such, it offers a patient-centred alternative to standard care and has the potential to reduce treatment barriers and improve access in resource-limited settings.

Xylazine is a veterinary sedative and widespread adulterant of illicit opioids, where it is commonly detected in combination with the potent synthetic µ opioid receptor (MOR) agonist fentanyl in fatal overdose. We used whole body plethysmography to evaluate the respiratory effects of xylazine in the presence and absence of fentanyl in awake C57BL/6 mice of both sexes. We asked whether suppression of breathing by xylazine-adulterated fentanyl resisted reversal with naloxone. We identified receptor mechanisms necessary to reverse effects of xylazine-adulterated fentanyl on breathing. Xylazine rapidly and dose-dependently suppressed minute ventilation, respiratory frequency, and tidal volume, producing profound respiratory depression at low doses. These effects were dependent on α-2 adrenergic receptors (α2ARs) and were blocked by the α2AR antagonist atipamezole. Xylazine, combined with a dose of fentanyl with modest respiratory effects, suppressed breathing with greater efficacy than when administered alone. A dose of naloxone sufficient to reverse fentanyl-induced respiratory depression was ineffective in reversing the respiratory suppression induced by xylazine-adulterated fentanyl. By contrast, combinations of naloxone with atipamezole rapidly and fully reversed respiratory suppression induced by xylazine-adulterated fentanyl. The same dose of atipamezole, administered alone, produced significant, but markedly delayed reversal. Xylazine suppresses breathing via activation of α2ARs, an effect enhanced by coadministration with the MOR agonist fentanyl. Respiratory suppression inflicted by the mixture of xylazine and fentanyl resisted reversal by naloxone but was fully reversible by subsequent coadministration of both naloxone and atipamezole.

Treating opioid use disorder (OUD) in pregnancy with sublingual buprenorphine is an evidence-based practice, but it has disadvantages that could be addressed with an extended-release formulation. To evaluate the effectiveness and safety of extended-release buprenorphine vs sublingual buprenorphine for OUD in pregnancy through 12 months post partum. This 2-group, open-label, noninferiority, randomized clinical trial was conducted between July 2, 2020, and October 30, 2024, among adults with OUD and a singleton pregnancy of 6 to 30 weeks' gestational age at 13 outpatient cross-disciplinary peripartum OUD treatment sites. Randomization to sublingual or extended-release buprenorphine (weekly formulation during pregnancy, monthly formulation optional post partum if not breastfeeding). The primary and key secondary outcomes were illicit opioid abstinence during pregnancy and the postpartum period, respectively, defined as the proportion of weekly collected urine samples negative for illicit opioids. If noninferiority was demonstrated at a margin of 0.15, testing for superiority was planned. Key secondary infant outcomes from medical records were opioid treatment for neonatal opioid withdrawal syndrome (NOWS; yes or no) and number of opioid treatment days for NOWS. Among 140 randomized participants, the mean (SD) age was 31.2 (4.6) years. There were 10 Black participants (7.1%), 10 Hispanic participants (7.1%), 116 (82.9%) White participants, and 14 participants (10.0%) who belonged to additional groups. All but 2 were already prescribed sublingual buprenorphine. Study completion was 98% through pregnancy (137 participants) and 81% through 12 months post partum (114 participants). Illicit opioid abstinence was higher during pregnancy for participants receiving extended-release vs sublingual buprenorphine (82.5% vs 72.6%; mean difference, 9.84 [95% CI, 1.72 to 17.95] percentage points; P = .009). Postpartum abstinence rates declined and were similar in both groups (60.2% vs 59.5%; mean difference, 0.65 [98% CI, -12.72 to 14.02] percentage points; P = .45). Those receiving extended-release buprenorphine experienced fewer serious adverse events during pregnancy (8.7% vs 26.8%; P = .007) and post partum (6.0% vs 18.6%; P = .04). Nonserious adverse events rates did not differ between groups, but more were deemed medication-related for extended-release participants during pregnancy (26.1% vs 7.0%; P = .003). Infants exposed to extended-release vs sublingual buprenorphine did not differ in need for opioid treatment (30.2% vs 26.5%; relative risk, 1.14 [98% CI, 0.54 to 1.99]; P = .64) or mean (SE) treatment days (10.9 [2.2] vs 14.8 [3.0] days; relative risk, 0.73 [98% CI, 0.36 to 1.51]; P = .28). At birth, extended-release-exposed neonates had larger mean (SE) head circumferences than those exposed to sublingual buprenorphine (34.0 [0.2] vs 33.4 [0.2] cm; mean difference, 0.63 [95% CI, -0.00 to 1.26] cm; P = .049). The findings of this randomized clinical trial support weekly extended-release buprenorphine for OUD treatment during pregnancy. ClinicalTrials.gov Identifier: NCT03918850.

SUMMARYThis review summarizes potential drug-drug interactions (DDIs) between long-acting antiretrovirals (LAAs) and opioids, focusing on pharmacodynamics (PD), pharmacokinetics (PK), and side effects related to absorption, distribution, metabolism, and excretion (ADME). It also covers dysregulation in epigenetics and in the immune system. A comprehensive literature review was performed using PubMed and Google Scholar, along with data from the Liverpool HIV Drug Interactions Database, to evaluate pharmacokinetic interactions between LAA drugs, such as cabotegravir, rilpivirine, lenacapavir, and dapivirine, with opioids used in clinical settings, including morphine, tramadol, oxycodone, and codeine; medications for opioid use disorder (MOUD), such as methadone and buprenorphine; and the illicit opioids, including fentanyl and heroin. The review highlights key factors increasing DDI risk and discusses clinical considerations for managing preexposure prophylaxis (PrEP) or antiretroviral therapy (ART) in persons who use opioids. Lastly, it proposes research strategies for studying DDIs, including the use of animal models, physiologically based pharmacokinetic (PBPK) models, and clinical trials.

Substance use and its associated comorbidities are a global public health crisis affecting millions of people, involving both legal and illicit substances, including cocaine, opioids, methamphetamine, fentanyl, alcohol, and marijuana. Currently, most of the research in drug abuse has been focused on the drug-mediated dysregulation of the monoaminergic and glutamatergic brain pathways because of their role in addiction, tolerance, dependence, withdrawal, and relapse. In addition, individuals using cocaine (acute and chronic) also exhibit signs of peripheral compromise, affecting the cardiovascular system, immune function, and multiple aging processes. However, the underlying mechanisms remain incompletely understood. Recently, emerging mechanisms of drug action, independent of neurotransmitter dysregulation, have been described in nonneuronal cells, helping to explain the significant burden of cardiovascular disease, immune compromise, and sudden death in the drug user population.

Clandestine fentanyl manufacturing oftentimes introduces adulterants and contaminants. This paper aims to evaluate trends in adulterants from a cohort of patients presenting to the emergency department (ED) with illicit opioid overdose across the United States. The Fentalog Study group is a multicenter toxicology study group which evaluated ED patients with suspected opioid overdose at 10 medical centers across the United States between September 21, 2020 through February 5, 2024. Comprehensive qualitative toxicology testing was performed on residual serum specimens. Study sites were divided into three geographic regions: West (California, Oregon, Colorado), Midwest (Missouri, Michigan), and East (New York, New Jersey, Pennsylvania, Georgia). Illicit opioids were defined as fentanyl and fentanyl analogs, heroin or its metabolites, and/or novel potent opioids such as nitazenes. 1295 patients with confirmed illicit opioid overdose were included. Males accounted for the majority (73.7%) of patients. The median age was 39 (IQR: 31-54) years. Adulterants were detected in 745 (57.5%) patients. Quinine was the most abundantly encountered adulterant (433; 33.4%). Antihistamines were the most frequently detected class of adulterants (19.6%). There were significant differences in adulterants detected across the three time periods, with notable decreases in adulterants from time-period 1 (79.5%) to time-period 3 (41.7%; p < 0.001). Adulterants were found in 84 (27.0%) of patients that presented to a hospital in the Western United States, compared with 181 (24.3%) in the Midwest, and 480 (64.4%) of patients in the East (p < 0.001). Patients with concurrent cocaine were more likely having an adulterant present than those without cocaine present (OR 1.23; 95% CI 1.15-1.31). In contrast, patients with illicit opioids and concurrent methamphetamine were less likely to have adulterants present (OR 0.89; 95% CI 0.84-0.95). Adulteration of illicit opioids was more likely in the Eastern United States and for those with concurrent cocaine and opioid exposures.

Xylazine, an alpha-2 adrenergic agonist veterinary sedative, has emerged as a frequent adulterant in illicit opioids, contributing to the ongoing "tranq dope" crisis. Its effects on human pregnancy are largely unknown, posing new challenges in obstetric addiction medicine. We present the case of a 25-year-old woman (G4P2113) with opioid use disorder who unknowingly used fentanyl adulterated with xylazine throughout pregnancy. She developed preeclampsia with HELLP syndrome, requiring urgent preterm cesarean delivery at 34 weeks. The neonate was treated for neonatal abstinence syndrome. Four days postpartum, the patient-discharged without medication for opioid use disorder-suffered intractable vomiting from withdrawal, leading to a Mallory-Weiss tear with massive hemorrhage and cardiac arrest. She required intensive care with transfusions, endoscopic hemostasis, and mechanical ventilation. Upon extubation, she disclosed fentanyl-xylazine ("tranq") use. She was transitioned to buprenorphine maintenance with supportive care for xylazine withdrawal and discharged in improved condition. We review the sparse human literature on xylazine exposure in pregnancy and relevant animal studies. Human data confirm placental transfer of xylazine, with umbilical cord assays detecting exposure, and suggest that xylazine may contribute to maternal CNS depression and neonatal sedation. Animal models demonstrate dose-dependent uterine vasoconstriction, reduced uteroplacental blood flow, fetal growth restriction, and pregnancy loss. We discuss management considerations for pregnant patients using xylazine-adulterated opioids, including challenges in diagnosis, withdrawal management, and the need for expanded harm-reduction strategies. This case and review highlight the urgent need for surveillance and evidence-based protocols to address xylazine in the perinatal setting.

Timely surveillance of opioid-related harm is critical to inform public health responses and policy evaluation. In Australia, where prescription and illicit opioids remain a leading cause of unintentional drug-induced deaths, emergency departments (ED) are a vital point of contact for acute opioid poisonings. Existing surveillance systems rely on structured coding, yet much relevant information is recorded in free-text fields, leading to underreporting or misclassification. This limits opportunistic identification of emerging patterns and weakens the evidence base for evaluating policy reforms. We aim to improve surveillance accuracy by applying natural language processing (NLP) to routinely collected ED data. Using medical concept annotation tools, we will develop models trained on 15 years of Victorian Emergency Minimum Dataset (VEMD) records. These models will analyse both unstructured and structured fields to identify opioid poisoning presentations and be validated against a manually coded gold standard using standard performance metrics. In the second phase, we will incorporate additional unstructured clinical information such as discharge summaries from hospital electronic records, which are not available in the VEMD data, thereby allowing more comprehensive and accurate classification. Finally, we will assess the utility of NLP-enhanced data in evaluating three major opioid policy changes. This study is the first to apply NLP at large scale to Australian ED data for drug poisonings. By improving the accuracy and consistency of opioid poisoning identification, this approach can strengthen routine surveillance and better inform timely policy and health system responses without increasing the workload for clinical staff.

Xylazine, an alpha-2 agonist used in veterinary anesthesia, is increasingly detected in the illicit opioid supply but little is known about the patient level factors associated with xylazine in non-fatal opioid overdose. This study aimed to determine the demographic and clinical factors associated with xylazine detection among emergency department (ED) patients with opioid overdose. Observational study. The Toxicology Investigators Consortium (ToxIC) Fentalog Study is a multicenter, prospective cohort of adult patients with suspected opioid overdose. This analysis included patients enrolled from September 2020 to September 2023. In this multicenter study, participating sites included 10 institutions across 9 states in 4 regions of the United States (US): Northeast, Southeast, Midwest and West. Patients were eligible for Fentalog Study inclusion if they were at least 18 years old, had a suspected opioid overdose and had waste blood available for toxicologic analysis. Only patients with qualitative serum detection of illicit opioids and/or xylazine were included in the final cohort. Of 5554 patients screened, 1289 were eligible for Fentalog Study inclusion. Based on results of liquid chromatography with a quadrupole time-of-flight mass spectrometer (LCQTOF-MS) and/or liquid chromatography with a triple quadrupole mass spectrometer (LC-QQQ-MS), patients were categorized into those with xylazine detected (positive cases) and without xylazine detected (negative controls). To determine clinical variables associated with xylazine detection, the primary outcome of interest was qualitative detection of xylazine on serum sampling by LCQTOF-MS. Xylazine was detected in 238 patients. Patients with xylazine were primarily male (78%), white (48%), non-Hispanic (82%) and located in the Northeast US (75%). Bradycardia on initial ED vital signs was associated with higher likelihood of xylazine detection (adjusted odds ratio = 2.11, 95% confidence interval = 1.06-4.06). Xylazine detection among emergency department opioid overdose patients appears to be more prevalent in the Northeast US and bradycardia appears to be a statistically significant clinical predictor.

The opioid crisis in the USA affects many people and results in a significant loss of life, degradation of health, and the social fabric. Opioid Use Disorder (OUD) is also a significant motivator for crime, both by opioid users themselves and in the illicit trade supplying them. The trade of illicit opioids is supported by geopolitical rivals of the USA (China) and criminal organizations, and is a significant source of income for criminal and terrorist organizations. It is therefore of vital national interest and national security to end the opioid crisis in the United States on the grounds of both health and national security. This trial protocol presents a means to lower the incidence of OUD, which lowers local crime, healthcare usage, and funding for criminal and terrorist organizations. Keywords: Opioid use disorder, opioid crisis, illicit trade, addiction, herbal medicine

With opioids being increasingly prescribed and illicit opioids being misused, substance use disorder has become a growing public health concern. The impacts of the opioid epidemic have been devastating, especially for pregnant people, infants, and children. Pre- and perinatal opioid exposure is complex. Opioids affect multiple body systems and have detrimental effects on the placenta, brain, and immune system. Pharmacological properties make each class of opioid unique, thereby compounding effects on development based on the type, receptors engaged, or combination of drugs used. Accordingly, animal models are necessary to elucidate the mechanisms, pathways, and developmental processes affected by opioid exposure during and after pregnancy. However, the complexity of opioid use in humans means that preclinical modeling is also complicated with variation by species type, duration, and timing of exposure, and combinations of opioids studied. In this chapter, we present a summary of numerous, intricate preclinical models of perinatal opioid exposure. Specifically, we discuss (1) the inherent variability and difficulty in modeling complex patterns of opioid use by pregnant and peripartum people, (2) provide background on opioids and their receptors, and (3) present evidence for long-term changes in brain structure and function secondary to prenatal opioid exposure. Together, we emphasize the significant immunological, structural, and cognitive changes documented in animals and humans after opioid exposure to highlight the potential for translatability and illustrate a path forward for improved mechanistic and therapeutic discovery.

In recent decades, opioid misuse has become a major global public health concern, with significant contributions to morbidity and mortality. Emergency departments (EDs) are frequent sites of opioid initiation, yet prescribing practices vary widely among physicians. Previous research in the Western region of Saudi Arabia demonstrated variability in prescribing influenced by physician demographics and experience. However, no prior study has assessed these patterns in the Qassim region. This study aimed to evaluate the pattern and influencing factors of opioid-prescribing behavior among emergency physicians in the Qassim region of Saudi Arabia. A cross-sectional study was conducted in March 2025 among emergency physicians in Qassim hospitals. A self-administered 22-item questionnaire assessed demographic and professional characteristics along with determinants of opioid-prescribing behavior using a five-point Likert scale. An overall agreement score was calculated. Descriptive statistics, t-tests, and one-way ANOVA with Tukey's post-hoc analysis were performed using SPSS v26, with p<0.05 considered significant. A total of 104 physicians completed the survey. The most highly rated determinants of prescribing were the patient's apparent distress (4.4±0.8), medications already administered (4.3±0.8), reported pain score (4.0±0.9), vital signs/physical exam findings (4.0±1.1), and diagnosis thought to be the cause of pain (4.0±0.9). The least influential factors were family/friends' experiences (1.9±1.0), the belief that EDs are a major source of illicit opioids (2.5±1.2), and colleagues' prescribing culture (2.6±1.2). The agreement score differed significantly by gender (p=0.007), number of shifts per month (p=0.004), and years of practice (p<0.001). Post-hoc analysis confirmed that physicians with >10 years of experience scored significantly higher than those with 1-2 years. Emergency physicians in Qassim demonstrated prescribing patterns primarily guided by objective clinical indicators of pain. Unlike the Western region, significant variation was observed by gender, workload, and years of practice. These findings highlight the need for structured educational interventions for junior physicians, optimization of shift schedules, and region-specific guidelines to ensure safe and consistent opioid prescribing.

The complexity and potency of the illicit opioid supply in North America has become increasingly concerning for people who use drugs. Drug checking efforts aim to keep up with the evolving psychoactive components present in the illicit drug supply. While targeted paper-spray mass spectrometry (PS-MS) methods are effective for trace detection and quantitation, they are limited in their ability to detect emerging substances. Here, we demonstrate the use of a support vector machine (SVM) classifier to detect opioid samples containing an additional component outside of a routine targeted analysis method, using ortho-methylfentanyl as proof of concept. This approach allows for the focused selection of samples for additional screening to identify emerging adulterants from full-scan data collected during a 2 min PS-MS analysis. The developed classifier achieved a precision of 0.77 and a recall of 0.94 for the detection of ortho-methylfentanyl in samples containing fentanyl and caffeine. Shapely additive explanations were used to explain and interpret the results of the developed SVM classifier, and enabled a better understanding of the composition of illicit opioids. Our work demonstrates a new and effective approach for identifying adulterants from unit mass resolution mass spectrometry data generated during routine on-site drug analysis.

BackgroundSubstance use disorder is a persistent public-health challenge in Iran, where multiple treatment settings operate in parallel. This study assessed within-modality changes over 12 months among clients in Methadone Maintenance Treatment (MMT), Drop-in Centers (DICs), Therapeutic Communities (TCs), compulsory (Article 16) treatment.MethodsA prospective, naturalistic cohort was conducted across 15 routine-care centers in Kerman Province (May 2023–May 2024). Of 493 enrolled, 470 completed follow-up (MMT/DIC at 12 months; TC/compulsory at end-of-treatment [EOT]). MMT/DIC were assessed at baseline, 2 months, and 12 months; TC/Article 16 at baseline and EOT. Outcomes were assessed using the Maudsley Addiction Profile (MAP). Within-modality changes from baseline were estimated with mixed-effects models in Stata 15, using two-sided tests (α = 0.05).ResultsMMT was associated with reductions in alcohol, opium, and heroin use, lower odds of interpersonal conflicts, fewer physical/psychological problems, and fewer days of illness-related unemployment. DIC showed decreases in physical/psychological problems, drug-related harms (e.g., dealing), and fighting; changes in spouse/relative/friend-conflict indicators were not statistically significant. TC showed short-term reductions in several substances; employment decreased during the residential phase (a programmatic constraint rather than a change in employability). Article 16 showed declines in selected substances and health problems during observation; durability post-discharge remains uncertain.ConclusionsFindings indicate domain-specific, within-modality changes rather than comparative effectiveness between settings. In TCs, short-term within-modality declines were observed in alcohol and selected illicit opioids at EOT alongside limited employment opportunities during residence due to programmatic restrictions. Within MMT, improvements were observed in selected psychosocial indicators at follow-up, consistent with stabilization during ongoing care. Within DICs, reductions were observed in health problems and certain risk behaviors, aligning with their harm-reduction and linkage role. Within Article 16, short-term declines were observed in selected substances and health problems during observation; durability after discharge is uncertain without structured aftercare. Overall, no single modality appears universally superior; matching clients to treatment according to target outcomes, and implementing stepped-care or blended pathways with robust post-treatment supports—particularly following compulsory programs—may optimize long-term impact.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12954-025-01346-1.

Opioid use, both prescribed and illicit, has caused considerable harm and fatalities. This study aims at characterising patterns of emergency department (ED) presentations related to opioid abuse across Europe. Data on demographics, clinical features, and epidemiology were extracted from the Euro-DEN Plus data set for presentations involving acute opioid toxicity between October 2013 and December 2021. Of 62,545 presentations, 3888 (6.2%) involved prescription opioids, 11,252 (18.0%) illicit opioids, and 587 (0.9%) both. Heroin accounted for 99.8% of illicit opioid cases. The most commonly reported prescription opioids were methadone (51.3%), buprenorphine (13.9%), morphine (9.3%), fentanyl (6.8%), and tramadol (6.7%). Co-use of benzodiazepines and Z-drugs (35.6%) and pregabalin (6.6%) was significantly higher in prescription opioid cases compared with illicit (20.6% and 1.5%, respectively; P < 0.001). Mortality was greater with prescription opioids (1.2%) than illicit opioids (0.4%, P < 0.001). Heroin remains the predominant opioid; though the relative contribution of prescription opioids varies significantly across centres and countries. Methadone and buprenorphine predominate among prescribed opioids, while fentanyl and oxycodone account for a small proportion, contrasting with North American patterns.

From addiction to aggression: The spillover effects of opioid policies on intimate partner violence.

Substances in fentanyl samples in the U.S. illicit drug supply: A decade of trends and regional variations using serial cross-sectional analysis.

Over 600,000 individuals are released from correctional institutions annually in the United States. Substance use disorders (SUDs) are highly prevalent in this population, and only a small proportion receive adequate treatment during incarceration. Post-incarceration, substance use increases considerably, and the risk of drug overdose is higher among formerly incarcerated individuals than among their counterparts in the general population, especially among individuals who use illicit opioids. However, significant gaps exist in our understanding of individual- and environment-level pathways of post-incarceration substance use, limiting treatment effectiveness. For those who receive substance use treatment services post-incarceration, research suggests that these services are not medically appropriate and/or responsive to their unique needs - thereby jeopardizing substance use outcomes. The Addiction Treatment Adequacy Post-Incarceration (ATAP) Study aims to examine individual and environmental factors associated with changes in substance use and substance use treatment adequacy over a one-year period post-incarceration among formerly incarcerated individuals in New York City (NYC). We will examine the extent to which participants receive appropriate substance use treatment services, as recommended by their scores on the American Society of Addiction Medicine patient placement criteria (ASAM PPC). We will use innovative spatially informed multi-level modeling strategies to investigate individual- and environment-level factors that influence substance use among individuals released from correctional institutions and residing in the NYC metropolitan area. Guided by social ecological theory, this study will address the following specific aims: 1) Characterize substance use over a 12-month period (every three months) among 350 formerly incarcerated individuals who have been released in NYC during the past three years; 2) Identify individual (e.g., race, gender, income, mental health) and environmental (e.g., proximity to drug purchasing sites, neighborhood characteristics, residential mobility, access to treatment services) risk factors for drug use among formerly incarcerated individuals; and 3) Investigate discrepancies between ASAM PPC composite scores (a measure of addiction severity) generated and levels of substance use treatment. The proposed research will identify substance use treatment gaps and influential factors that are amenable to intervention in the interest of informing effective responses to the current opioid crisis.

Introduction Methadone maintenance treatment (MMT) is among the best strategies for reducing harms associated with illegal opioid use, yet it is hindered by low rates of treatment initiation and retention that limit its impact. There has been a lack of studies that describe how people who use illegal opioids use methadone–both from opioid treatment programs, and bought illegally–over time, or what factors correlate with long-term participation in MMT. Methods We collected monthly survey data from N = 412 people who use illicit opioids in New York City from April 2019–2022. We used bivariate analyses to estimate the distribution of baseline sociodemographic and background characteristics. Multinomial logistic regression was then used to estimate the association between those characteristics and methadone use over time. Results Findings show that people who are older, who used heroin for longer amounts of time, and who had multiple episodes of substance use disorder treatment other than medication for opioid use disorder are more likely to use MMT consistently over time. Discussion Our findings may be related to the many barriers to long-term participation in MMT, such as travel distance, the need for regular attendance, and patients’ dissatisfaction with opioid treatment programs. Consistent participation in MMT may become acceptable only when the difficulties and burdens of criminalized drug use begin to outweigh those of MMT participation, and after non-medication-using treatments have already been tried. Efforts to make MMT less burdensome could reduce the tendency to avoid MMT until later in life and improve people’s consistency of participation over time.