The Evolving Overdose Epidemic: Synthetic Opioids and Rising Stimulant-Related Harms

Exploring racial and secondary substance use differences in route of administration of opioid drugs: Analysis of the 2015-2019 treatment admission data

INTRODUCTION

The opioid crisis continues to evolve with increasing opioid-related overdose deaths among under-represented minorities. A better understanding of substance use differences in the route of administration for people using heroin and other opioids can lead to targeted strategies and interventions.

METHODS

Using the 2015-2019 Treatment Episode Data Set - Admissions (TEDS-A), a multinomial logistic regression model examined the relationship between race/ethnicity and secondary substance use with route of administration in a subset of 591,078 admissions.

RESULTS

For individuals reporting heroin as their primary substance, minoritized clients were both more likely to smoke (NH Blacks RR: 2.28, 95 % CI 2.16-2.41; Hispanic RR: 1.80, 95 % CI: 1.74, 1.87; Other RR: 2.09, 95 % CI: 2.00, 2.20) or inhale heroin (Hispanic RR: 1.82, 95 % CI 1.78-1.85; Other RR: 1.30, 95 % CI 1.25, 1.34) compared to non-Hispanic (NH) Whites. NH Black clients were nearly seven and a half times more likely to report inhaling (RR: 7.45, 95 % CI 7.28, 7.62) heroin over injecting it. Clients were more likely to smoke heroin compared to injection if they reported secondary drug use of methamphetamines (RR: 2.28, 95 % CI 2.21, 2.35) and other opioids (RR: 1.21, 95 % CI 1.15, 1.28). For clients reporting other opioids as their primary substance, Hispanic (RR: 1.33, 95 % CI 1.19, 1.47) and other racial/ethnic minority clients (RR: 2.50, 95 % CI 2.23, 2.79) were more likely to smoke opioids vs take it orally compared to their NH White counterparts. Individuals who reported methamphetamine use as a secondary substance were significantly more than three times as likely to smoke (RR: 3.07, 95 % CI 2.74, 3.45) or inject (RR: 3.36, 95 % CI 3.17, 3.57) compared to orally ingesting opioids, while those who reported cocaine or crack cocaine use were more than twice as likely to inject (RR: 2.22, 95 % CI 2.09-2.36) opioids than taking them orally.

CONCLUSION

Findings demonstrate significant racial and ethnic differences in the route of administration. This work expands on the understanding of the complex nature of polysubstance use in the evolving opioid crisis and the secondary substance use of clients on routes of administration of opioids and heroin, highlighting the need for tailored interventions to address the treatment needs of under-represented minorities.

Evaluation of in-house drug evidence testing by King County Medical Examiner's Office in "real-time" fatal overdose surveillance

With the escalating overdose epidemic, many surveillance efforts have appeared. In 2018, King County Medical Examiner's Office (KCMEO) initiated a fatal overdose surveillance project aimed at expediting death certification and disseminating timely information. In this project, KCMEO investigators collected items of evidence of drug use from overdose death scenes, which were tested by five in-house methods, four using handheld devices: TruNarc Raman spectrometer, with and without the manufacture's H-Kit, Rigaku ResQ Raman spectrometer, and MX908 mass spectrometer. The fifth in-house method used fentanyl-specific urine test strips. Results from in-house testing were compared with results from Washington State Patrol (WSP) Materials Analysis Laboratory. From 2019 to 2022, there were 4244 evidence items of drugs and paraphernalia collected from 1777 deaths scenes. A total of 7526 in-house tests were performed on collected specimens, and 2153 tests were performed by the WSP laboratory using standard analytical methods. The WSP results served as reference standards to calculate performance metrics of the in-house methods. Sensitivities, specificities, and predictive values ranged from good to poor depending on the method, drug, and evidence type. Certain drugs were often associated with specific evidence types. Acetaminophen was frequently found in combination with fentanyl. Fentanyl test strips gave good scores for detecting fentanyl; otherwise, in-house methods using handheld devices had poor performance scores with novel drugs and drugs diluted in mixtures. The results showed that in-house testing of drug evidence has value for medical examiner overdose surveillance, but it is resource intensive, and success depends on collaboration with forensic laboratories.

Associations among drug acquisition and use behaviors, psychosocial attributes, and opioid-involved overdoses

AIMS

This study sought to develop and assess an exploratory model of how demographic and psychosocial attributes, and drug use or acquisition behaviors interact to affect opioid-involved overdoses.

DESIGN

We conducted exploratory and confirmatory factor analysis (EFA/CFA) to identify a factor structure for ten drug acquisition and use behaviors. We then evaluated alternative structural equation models incorporating the identified factors, adding demographic and psychosocial attributes as predictors of past-year opioid overdose.

SETTING AND PARTICIPANTS

We used interview data collected for two studies recruiting opioid-misusing participants receiving services from a community-based syringe services program. The first investigated current attitudes toward drug-checking (N = 150). The second was an RCT assessing a telehealth versus in-person medical appointment for opioid use disorder treatment referral (N = 270).

MEASUREMENTS

Demographics included gender, age, race/ethnicity, education, and socioeconomic status. Psychosocial measures were homelessness, psychological distress, and trauma. Self-reported drug-related risk behaviors included using alone, having a new supplier, using opioids with benzodiazepines/alcohol, and preferring fentanyl. Past-year opioid-involved overdoses were dichotomized into experiencing none or any.

FINDINGS

The EFA/CFA revealed a two-factor structure with one factor reflecting drug acquisition and the second drug use behaviors. The selected model (CFI = .984, TLI = .981, RMSEA = .024) accounted for 13.1% of overdose probability variance. A latent variable representing psychosocial attributes was indirectly associated with an increase in past-year overdose probability (β = .234, p = .001), as mediated by the EFA/CFA identified latent variables: drug acquisition (β = .683, p < .001) and drug use (β = .567, p = .001). Drug use behaviors (β = .287, p = .04) but not drug acquisition (β = .105, p = .461) also had a significant, positive direct effect on past-year overdose. No demographic attributes were significant direct or indirect overdose predictors.

CONCLUSIONS

Psychosocial attributes, particularly homelessness, increase the probability of an overdose through associations with risky drug acquisition and drug-using behaviors. Further research is needed to replicate these findings with populations at high-risk of an opioid-related overdose to assess generalizability and refine the metrics used to assess psychosocial characteristics.

Informing evidence-based medicine for opioid use disorder using pharmacoeconomic studies

INTRODUCTION

The health and economic consequences of inadequately treated opioid use disorder (OUD) are substantial. Healthcare systems in the United States (US) and other countries are facing a growing healthcare crisis due to opioids. Although effective medications for OUD exist, relying solely on clinical information is insufficient for addressing the opioid crisis.

AREAS COVERED

In this review, the role of pharmacoeconomic studies in informing evidence-based medication treatment for OUD is discussed, with a particular emphasis on the US healthcare system, where the economic burden is significantly higher than the global average. The scope/objective of pharmacoeconomics as a distinct scientific research program is briefly defined, followed by a discussion of existing evidence informed by data from systematic reviews, in addition to a convenience sample of recently published pharmacoeconomic studies and protocols. The review also explores the need for methodological advancements in the field.

EXPERT OPINION

Despite the potential of pharmacoeconomic research in shaping evidence-based medicine for OUD, significant challenges limiting its real-world application remain. How to address these challenges are explored, including how to combine cost-effectiveness and budget impact analyses to address the needs of the healthcare system as a whole and specific stakeholders interested in adopting new OUD treatment strategies.

National and regional trends in seizures of shrooms (psilocybin) in the United States, 2017-2022

BACKGROUND

Psilocybin, the principle psychoactive component in "shrooms", is regaining acceptance in therapeutic settings, leading to media coverage of medical benefits associated with use. Possession is also becoming increasingly decriminalized throughout the United States. There is a lack of data on prevalence of shroom use, but trends in law enforcement seizure data can provide one indicator of shroom availability in US communities. We determined whether seizures of shrooms have shifted between 2017 and 2022.

METHODS

This study examined national and regional trends in counts and total weight of shroom seizures reported to High Intensity Drug Trafficking Areas in the US between 2017 and 2022 (N=4526).

RESULTS

There were 402 seizures in 2017 compared to 1396 in 2022 with the plurality occurring in the Midwest (36.0%), followed by the West (33.5%). Between 2017 Quarter 1 (Q1) and 2022 Quarter 4 (Q4), the number of seizures increased by 368.9% (AQPC=7.0; 95 CI: 5.9-8.1) and there were significant increases in all four regions. In terms of weight, 226.0kg was seized in 2017 vs. 844.0kg in 2022, and the greatest total weight in seizures was in the West (1864.2kg, 42.6%), followed by the South (1831.9kg, 41.8%). Between 2017 Q1 and 2022 Q4, the total weight seized in the US increased by 2749.7% (AQPC=6.2, 95% CI: 0.3-12.4) and there were significant increases in all four regions.

CONCLUSIONS

Seizures of shrooms have increased, suggesting that availability may be escalating; thus, increases in prevention efforts and harm reduction education are warranted.

Harm Reduction for Opioid Use Disorder: Strategies and Outcome Metrics

Tweet: The authors discuss harm reduction strategies and associated outcome metrics in relation to the ongoing opioid crisis.

Managing Opioid Withdrawal Symptoms During the Fentanyl Crisis: A Review

Illicitly manufactured fentanyl (IMF) is a significant contributor to the increasing rates of overdose-related deaths. Its high potency and lipophilicity can complicate opioid withdrawal syndromes (OWS) and the subsequent management of opioid use disorder (OUD). This scoping review aimed to collate the current OWS management of study populations seeking treatment for OWS and/or OUD directly from an unregulated opioid supply, such as IMF. Therefore, the focus was on therapeutic interventions published between January 2010 and November 2023, overlapping with the period of increasing IMF exposure. A health science librarian conducted a systematic search on November 13, 2023. A total of 426 studies were screened, and 173 studies were reviewed at the full-text level. Forty-nine studies met the inclusion criteria. Buprenorphine and naltrexone were included in most studies with the goal of transitioning to a long-acting injectable version. Various augmenting agents were tested (buspirone, memantine, suvorexant, gabapentin, and pregabalin); however, the liberal use of adjunctive medication and shortened timelines to initiation had the most consistently positive results. Outside of FDA-approved medications for OUD, lofexidine, gabapentin, and suvorexant have limited evidence for augmenting opioid agonist initiation. Trials often have low retention rates, particularly when opioid agonist washout is required. Neurostimulation strategies were promising; however, they were developed and studied early. Precipitated withdrawal is a concern; however, the rates were low and adequately mitigated or managed with low- or high-dose buprenorphine induction. Maintenance treatment continues to be superior to detoxification without continued management. Shorter induction protocols allow patients to initiate evidence-based treatment more quickly, reducing the use of illicit or non-prescribed substances.

Plasma drug screening using paper spray mass spectrometry with integrated solid phase extraction

Drug overdoses have risen dramatically in recent years. We developed a simple nontargeted method using a disposable paper spray cartridge with an integrated solid phase extraction column. This method was used to screen for ~160 fentanyl analogs, synthetic cannabinoids, other synthetic drugs, and traditional drugs of abuse in over 300 authentic overdose samples collected at emergency departments in Indianapolis. A solid phase extraction step was implemented on the paper spray cartridge to enable subnanograms per milliliter synthetic drugs screening in plasma. Analysis was performed on a quadrupole orbitrap mass spectrometer using the sequential window acquisition of all theoretical fragment ion spectra approach in which tandem mass spectrometry was performed using 7 m/z isolation windows in the quadrupole. Calibration curves with isotopically labeled internal standards were constructed for 35 of the most frequently encountered synthetic and traditional illicit drugs by US toxicology labs. Additional qualitative-only drugs in a suspect screening list were also included. Limits of detection in plasma for synthetic cannabinoids ranged from 0.1 to 0.5 and 0.1 to 0.3 ng/mL for fentanyl and its analogs and between 1 and 5 ng/mL for most other drugs. Relative matrix effects were evaluated by determining the variation of the calibration slope in 10 different lots of biofluid and found to be between 3% and 20%. The method was validated on authentic overdose samples collected from two emergency departments in Indianapolis, Indiana, from suspected or known overdoses. Commonly detected synthetic drugs included fentanyl related substances, designer benzodiazepines such as flubromazolam, and the synthetic cannabinoid 5F-PB-22.

A brief measure of non-drug reinforcement: Association with treatment outcomes during initial substance use recovery

BACKGROUND

Translational research demonstrates that drug use is inversely associated with availability and engagement with meaningful non-drug reinforcers. Evaluation of non-drug reinforcement in treatment-receiving clinical populations is limited, likely owing to the time intensive nature of existing measures. This study explores the association of non-drug reinforcers with treatment outcomes using a novel, brief measure of past month non-drug reinforcement quantifying three elements: relative frequency, access, and enjoyability.

METHODS

Respondents enrolled in substance use treatment (residential, intensive outpatient, and medically managed withdrawal) in clinics across the United States (N = 5481) completed standardized assessments of non-drug reinforcement and treatment outcomes (i.e., return to use and life satisfaction) one-month after treatment discharge. Non-drug reinforcement measures (availability, engagement, enjoyability) were used as predictors of return to use and life satisfaction using generalized linear models.

RESULTS

Non-drug reinforcement indices were associated with return to use and life satisfaction in unadjusted models (e.g., 12.4 % versus 58.3 % return to use for those with the highest and lowest availability, respectively). Consistent results were observed in models adjusted for sociodemographic variables and risk factors (i.e., sleep disturbance, anhedonia, stress). Comparisons by drug class generally showed lower non-drug reinforcement among patients reporting heroin or methamphetamine as their primary drug.

CONCLUSIONS

Results highlight the importance of non-drug reinforcement during the first month following treatment. Rapid measurement of non-drug reinforcement in stepped care settings may illuminate critical deficits in early stages of behavior change, identify those at greatest risk for return to use, and provide targets for treatment to improve recovery trajectories.

Associations among Drug Acquisition and Use Behaviors, Psychosocial Attributes, and Opioid-Involved Overdoses: A SEM Analysis

Aims

This study sought to develop and assess an exploratory model of how demographic and psychosocial attributes, and drug use or acquisition behaviors interact to affect opioid-involved overdoses.

Methods

We conducted exploratory and confirmatory factor analysis (EFA/CFA) to identify a factor structure for ten drug acquisition and use behaviors. We then evaluated alternative structural equation models incorporating the identified factors, adding demographic and psychosocial attributes as predictors of past-year opioid overdose. We used interview data collected for two studies recruiting opioid-misusing participants receiving services from a community-based syringe service program. The first investigated current attitudes toward drug-checking (N = 150). The second was an RCT assessing a telehealth versus in-person medical appointment for opioid use disorder treatment referral (N = 270). Demographics included gender, age, race/ethnicity, education, and socioeconomic status. Psychosocial measures were homelessness, psychological distress, and trauma. Self-reported drug-related risk behaviors included using alone, having a new supplier, using opioids with benzodiazepines/alcohol, and preferring fentanyl. Past-year opioid-involved overdoses were dichotomized into experiencing none or any.

Results

The EFA/CFA revealed a two-factor structure with one factor reflecting drug acquisition and the second drug use behaviors. The selected model (CFI = .984, TLI = .981, RMSEA = .024) accounted for 13.1% of overdose probability variance. A latent variable representing psychosocial attributes was indirectly associated with an increase in past-year overdose probability (β=.234, p = .001), as mediated by the EFA/CFA identified latent variables: drug acquisition (β=.683, p < .001) and drug use (β=.567, p = .001). Drug use behaviors (β=.287, p = .04) but not drug acquisition (β=.105, p = .461) also had a significant, positive direct effect on past-year overdose. No demographic attributes were significant direct or indirect overdose predictors.

Conclusions

Psychosocial attributes, particularly homelessness, increase the probability of an overdose through associations with risky drug acquisition and drug-using behaviors. To increase effectiveness, prevention efforts might address the interacting overdose risks that span multiple functional domains.

Influence of ZnO morphology on the capability of portable paper-based electrospray ionization mass spectrometry to determine therapeutic drugs in complex matrices

Adsorbents play a significant role in enhancing the analytical sensitivity of target analytes in complex samples by mitigating matrix effects. In our recent report, ZnO stood out among various adsorbents to determine target therapeutic drugs in complex biological matrices when applied for portable paper-based electrospray ionization mass spectrometry (PPESI-MS). However, the influence of the morphology of ZnO on the performance of PPESI-MS is elusive. Herein, different morphologies of ZnO particles were prepared via co-precipitation or ultrasonic methods, and their capability to determine different therapeutic drugs in serum were systemically investigated. The results demonstrated that flower-shaped ZnO gave a superior capacity, and its analysis sensitivity was 2.9-12.8-fold higher than those achieved with other ZnO morphologies. Further characterization revealed that the unique performance of flower-shaped ZnO was closely associated with its favorable desorption behavior to drugs, small spray plume, and few spray emitters at the tip of coated paper substrate. To illustrate the potential of flower-shaped ZnO, its coated paper was used as a substrate for the determination of various drugs in complex matrices such as serum, and a limit of detection as low as 2 pg mL-1 was achieved. The corresponding recoveries ranged from 93.2% to 107.2%. The developed protocol is promising in high-sensitivity analysis of target drugs in complex sample matrices.

Polysubstance mortality trends in White and Black Americans during the opioid epidemic, 1999-2018

BACKGROUND

Psychoactive drug combinations are increasingly contributing to overdose deaths among White and Black Americans. To understand the evolving nature of overdose crisis, inform policies, and develop tailored and equitable interventions, this study provides a comprehensive assessment of polysubstance mortality trends by race and sex during the opioid epidemic.

METHODS

We used serial cross-sectional US mortality data for White and Black populations from 1999 through 2018 to calculate annual age-adjusted death rates (AADR) involving any opioid, opioid subtypes, benzodiazepines, cocaine, psychostimulants, or combinations of these drugs, stratified by race and sex. Trend changes in AADR were analyzed using joinpoint regression models and expressed as average annual percent change (AAPC) during each period of the three waves of the opioid epidemic: 1999-2010 (wave 1), 2010-2013 (wave 2), and 2013-2018 (wave 3). Prevalence measures assessed the percent co-involvement of an investigated drug in the overall death from another drug.

RESULTS

Polysubstance mortality has shifted from a modest rise in death rates due to benzodiazepine-opioid overdoses among White persons (wave 1) to a substantial increase in death rates due to illicit drug combinations impacting both White and Black populations (wave 3). Concurrent cocaine-opioid use had the highest polysubstance mortality rates in 2018 among Black (5.28 per 100,000) and White (3.53 per 100,000) persons. The steepest increase in death rates during wave 3 was observed across all psychoactive drugs when combined with synthetic opioids in both racial groups. Since 2013, Black persons have died faster from cocaine-opioid and psychostimulant-opioid overdoses. Between 2013 and 2018, opioids were highly prevalent in cocaine-related deaths, increasing by 33% in White persons compared to 135% in Blacks. By 2018, opioids contributed to approximately half of psychostimulant and 85% of benzodiazepine fatal overdoses in both groups. The magnitude and type of drug combinations with the highest death rates differed by race and sex, with Black men exhibiting the highest overdose burden beginning in 2013.

CONCLUSIONS

The current drug crisis should be considered in the context of polysubstance use. Effective measures and policies are needed to curb synthetic opioid-involved deaths and address disparate mortality rates in Black communities.

Oxycodone, an opioid like the others?

The over-prescription of opioid analgesics is a growing problem in the field of addiction, which has reached epidemic-like proportions in North America. Over the past decade, oxycodone has gained attention as the leading opioid responsible for the North America opioid crisis. Oxycodone is the most incriminated drug in the early years of the epidemic of opioid use disorder in USA (roughly 1999-2016). The number of preclinical articles on oxycodone is rapidly increasing. Several publications have already compared oxycodone with other opioids, focusing mainly on their analgesic properties. The aim of this review is to focus on the genomic and epigenetic regulatory features of oxycodone compared with other opioid agonists. Our aim is to initiate a discussion of perceptible differences in the pharmacological response observed with these various opioids, particularly after repeated administration in preclinical models commonly used to study drug dependence potential.

Amphetamine-Related Emergency Department Visits in Ontario, Canada, 2003-2020

OBJECTIVES

Despite unregulated amphetamine use increasing, there are limited data on related emergency department (ED) visits in Canada. Our primary objective was to examine trends in amphetamine-related ED visits over time in Ontario, including by age and sex. Secondary objectives were to examine whether patient characteristics were associated with ED revisit within 6 months.

METHODS

Using administrative claims and census data, we calculated annual patient- and encounter-based rates of amphetamine-related ED visits from 2003 to 2020 among individuals 18+ years of age. We also performed a retrospective cohort study of individuals with amphetamine-related ED visits between 2019 and 2020 to determine whether select factors were associated with ED revisit within 6 months. Multivariable logistic regression modelling was used to measure associations.

RESULTS

The population-based rate of amphetamine-related ED visits increased nearly 15-fold between 2003 (1.9/100,000 Ontarians) and 2020 (27.9/100,000 Ontarians). Seventy-five percent of individuals returned to the ED for any reason within 6 months. Psychosis and use of other substances were both independently associated with ED revisit for any reason within 6 months (psychosis: AOR = 1.54, 95% CI = 1.30-1.83; other substances: AOR = 1.84, 95% CI = 1.57-2.15), whereas having a primary care physician was negatively associated with ED revisit (AOR = 0.77, 95% CI = 0.60-0.98).

CONCLUSIONS

Increasing rates of amphetamine-related ED visits in Ontario are cause for concern. Diagnoses of psychosis and the use of other substances may serve to identify individuals who are most likely to benefit from both primary and substance-specific care.

Social vulnerability predictors of drug poisoning mortality: A machine learning analysis in the United States

BACKGROUND AND OBJECTIVES

Drug poisoning is a leading cause of unintentional deaths in the United States. Despite the growing literature, there are a few recent analyses of a wide range of community-level social vulnerability features contributing to drug poisoning mortality. Current studies on this topic face three limitations: often studying a limited subset of vulnerability features, focusing on small sample sizes, or solely including local data. To address this gap, we conducted a national-level analysis to study the impacts of several social vulnerability features in predicting drug mortality rates in the United States.

METHODS

We used machine learning to investigate the role of 16 social vulnerability features in predicting drug mortality rates for US counties in 2014, 2016, and 2018-the most recent available data. We estimated each vulnerability feature's gain relative contribution in predicting drug poisoning mortality.

RESULTS

Among all social vulnerability features, the percentage of noninstitutionalized persons with a disability is the most influential predictor, with a gain relative contribution of 18.6%, followed by population density and the percentage of minority residents (13.3% and 13%, respectively). Percentages of households with no available vehicles, mobile homes, and persons without a high school diploma are the following features with gain relative contributions of 6.3%, 5.8%, and 5.1%, respectively.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

We identified social vulnerability features that are most predictive of drug poisoning mortality. Public health interventions and policies targeting vulnerable communities may increase the resilience of these communities and mitigate the overdose death and drug misuse crisis.

Trends in Fentanyl Content on Reddit Substance Use Forums, 2013-2021

BACKGROUND

Fentanyl is a pressing concern in the current drug supply. Social media data can provide access to near real-time understanding of drug trends that may complement official mortality data.

DESIGN

The total number of fentanyl-related posts and the total number of posts for eight drug subreddit categories (alcohol, cannabis, hallucinogens, multi-drug, opioids, over the counter, sedatives, stimulants) were collected from 2013 to 2021 using the Pushshift Reddit dataset. The proportion of fentanyl-related posts as a fragment of total subreddit posts was examined. Linear regressions described the rate of change in post volume over time.

RESULTS

Overall, fentanyl-related content increased across drug-related subreddits from 2013 to 2021 (1292% increase, linear trend p ≤ 0.001). Opioid subreddits (30.62 per 1000 posts, linear trend p ≤ 0.001) had the most fentanyl-related content during the examined time period. Multi-drug (5.95 per 1000; p ≤ 0.01), sedative (3.23 per 1000, p ≤ 0.01), and stimulant (1.60 per 1000, p ≤ 0.01) subreddits also had substantial increases in fentanyl-related content. The greatest increases occurred in the multi-drug (1067% 2013:2021) and stimulant (1862% 2014:2021) subreddits.

CONCLUSION

Fentanyl-related posts on Reddit trended upward, with the fastest rate of change for multi-substance and stimulant subreddits. Beyond opioids, harm reduction and public health messaging should ensure inclusion of individuals who use other drugs.

URINE TOXICOLOGY PROFILES OF EMERGENCY DEPARTMENT PATIENTS WITH UNTREATED OPIOID USE DISORDER: A MULTI-SITE VIEW

BACKGROUND

Opioid overdose deaths in 2021 were the highest ever, driven by fentanyl and polysubstance use.

OBJECTIVE

The aim of the study was to characterize drug use, assessed by urine drug screens (UDSs), in patients with untreated opioid use disorder (OUD) presenting to 28 emergency departments (EDs) nationally and by region.

METHODS

We analyzed UDSs from patients enrolled in the CTN-0099 ED-INNOVATION (Emergency Department-Initiated Buprenorphine Validation) trial between July 12, 2020 and March 9, 2022. Participants were adult ED patients with OUD not engaged in addiction treatment with a UDS positive for an opioid, but negative for methadone. Sites were divided into "East" and "West" regions.

RESULTS

A UDS was available for all 925 enrolled participants, 543 from East and 382 from West. Fentanyl was in 702 specimens (76%) (n = 485 [89%] East vs. n = 217 [57%] West; p < 0.01) and was the only opioid in 269 (29%). After fentanyl, the most common opioids were morphine (presumably heroin; n = 411 [44%]; n = 192 [35%] East vs. n = 219 [57%] West; p < 0.01) and buprenorphine (n = 329 [36%]; n = 186 [35%] East vs. n = 143 [37%] West; p = 0.32). The most common drugs found with opioids were stimulants (n = 545 [59%]), tetrahydrocannabinol (n = 417 [45%]), and benzodiazepines (n = 151 [16%]). Amphetamine-type stimulants were more common in West (n = 209 [55%] vs. East (n = 125 [23%]). Cocaine was more common in East (n = 223 [41%]) vs. West (n = 82 [21%]). The presence of multiple drugs was common (n = 759 [82%]).

CONCLUSIONS

Most participants had UDS specimens containing multiple substances; a high proportion had fentanyl, stimulants, and buprenorphine. Regional differences were noted. Given the increased risk of death with fentanyl and polysubstance use, ED providers should be providing risk reduction counseling, treatment, and referral.

Medical examiner response to the drug overdose epidemic in King County Washington: "Real-time" surveillance, data science, and applied forensic epidemiology

As the overdose epidemic overwhelmed medicolegal death investigation offices and toxicology laboratories, the King County Medical Examiner's Office responded with "real-time" fatal overdose surveillance to expedite death certification and information dissemination through assembling a team including a dedicated medicolegal death investigator, an information coordinator, and student interns. In-house testing of blood, urine, and drug evidence from scenes was performed using equipment and supplies purchased for surveillance. Collaboration with state laboratories allowed validation. Applied forensic epidemiology accelerated data dissemination. From 2010 to 2022, the epidemic claimed 5815 lives in King County; the last 4 years accounted for 47% of those deaths. After initiating the surveillance project, in-house testing was performed on blood from 2836 decedents, urine from 2807, and 4238 drug evidence items from 1775 death scenes. Time to complete death certificates decreased from weeks to months to hours to days. Overdose-specific information was distributed weekly to a network of law enforcement and public health agencies. As the surveillance project tracked the epidemic, fentanyl and methamphetamine became dominant and were associated with other indicators of social deterioration. In 2022, fentanyl was involved in 68% of 1021 overdose deaths. Homeless deaths increased sixfold; in 2022, 67% of 311 homeless deaths were due to overdose; fentanyl was involved in 49% and methamphetamine in 44%. Homicides increased 250%; in 2021, methamphetamine was positive in 35% of 149 homicides. The results are relevant to the value of rapid surveillance, its impact on standard operations, selection of cases requiring autopsy, and collaboration with other agencies in overdose prevention.

Trends and correlates of abscess history among people who inject drugs in Massachusetts: A mixed methods exploration of experiences amidst a rapidly evolving drug supply

Background

Injection drug use poses significant risk for skin and soft tissue infections, such as abscesses. In places with endemic fentanyl and an increasingly contaminated drug supply, injecting and injection-related harms may be increasing, yet are understudied. We aimed to explore abscess prevalence, experiences, and themes among people who inject drugs (PWID) in the context of an evolving drug supply.

Methods

Between 2019 and 2022, we surveyed and interviewed Massachusetts- based PWID about current drug use behaviors and abscess experiences. Chi-square tests explored correlates of abscess history and trends for past-year abscess percentages over time. Transcribed interview data were analyzed to identify themes related to abscess risk and opportunities for intervention.

Results

Of the 297 PWID surveyed, 65.3% reported having an abscess at the injection site in their lifetime; 67.5% of these instances occurred within the last year. Reported past-year abscesses increased from 36.7% to 75.6% between 2019 and 2022. Correlates of past-year abscesses included frequent injection; methamphetamine, crack, or fentanyl use; and injection into the neck or calf. Methadone treatment was associated with significantly fewer recent abscesses. Interview data (n=151) confirmed the identified abscess risks, including syringe sharing and lack of hygienic supplies. Qualitative interviews provided additional data regarding healthcare provider stigma contributing to healthcare avoidance and the self-treatment of abscesses with adverse results.

Conclusions

Abscesses are an increasing concern among PWID residing in areas of high fentanyl prevalence and a contaminated drug supply. Community drug checking, overdose prevention sites, injection hygiene interventions, and improved access to care are indicated.

State-Level History of Overdose Deaths Involving Stimulants in the United States, 1999‒2020

Objectives. To examine the state-level history of US overdose deaths involving stimulants with and without opioids from 1999 to 2020. Methods. We used death certificate data from the National Center for Health Statistics to categorize deaths into 4 groups of interest: cocaine with and without opioids, and psychostimulants with and without opioids. We used a Bayesian multiple change point model to describe the timing and magnitude of changes in overdose death rates involving stimulants for each state and year. Results. There was little change in the death rates of cocaine without opioids. Death rates involving cocaine and opioids sharply increased around 2015, particularly in the Northeast and Mid-Atlantic. We also observed steady increases in deaths involving psychostimulants without opioids just before 2010, particularly in states in the West and South. Deaths involving psychostimulants with opioids increased around 2015 with largest increases concentrated in Appalachian states. Conclusions. There is significant geographic heterogeneity in the co-involvement of stimulants in the US overdose crisis. Results can inform public health efforts to inform state-level overdose efforts such as naloxone distribution. (Am J Public Health. 2023;113(9):991-999. https://doi.org/10.2105/AJPH.2023.307337).

Socioeconomic marginalization and risk of overdose in a community-recruited cohort of people who use drugs: A longitudinal analysis

BACKGROUND

Poverty and socioeconomic disadvantage are important contributors to drug-related harm, but their precise role in overdose risk remains poorly understood. We sought to examine linkages between socioeconomic marginalization and non-fatal overdose risk in a community deeply affected by the ongoing drug poisoning crisis.

METHODS

This observational study used data derived from two community-recruited prospective cohorts of people who use drugs (PWUD) in Vancouver, British Columbia, Canada. Generalized linear mixed-effects models were used to assess longitudinal associations between multiple dimensions of socioeconomic disadvantage and self-reported non-fatal overdose.

RESULTS

Between 2014 and 2020, 1,493 participants (38.2% women; 59.6% white; 35.7% Indigenous) provided 9,968 interviews. Non-fatal overdose was reported by 32.5% of participants over the study period. In multivariable analyses, non-fatal overdose was independently associated with incarceration (adjusted odds ratios [AOR]: 1.42, 95% confidence interval [CI]: 1.08-1.88, p=0.012), homelessness (AOR: 1.57, 95%CI: 1.27-1.93, p<0.001), increased monthly income (AOR: 1.01, 95%CI: 1.00-1.01, p=0.029), and lower material security (AOR: 0.76, 95%CI: 0.67-0.88, p<0.001). We also observed differing strengths of association between illegal income generation and overdose in men (AOR: 1.84, 95%CI: 1.46-2.32, p<0.001) compared to women (AOR: 1.37, 95%CI: 1.06-1.78, p=0.016).

CONCLUSION

Non-fatal overdose was positively associated with incarceration, homelessness, higher monthly income, material insecurity, and engagement illegal income generating activities, underscoring the importance of addressing the socioeconomic production of overdose risk. These initiatives may include supportive housing interventions, alternative economic supports, and broader drug policy reform.

Trends in cocaine and crystal methamphetamine injection over time in a Canadian setting between 2008 and 2018

OBJECTIVE

Unregulated stimulant use is rising globally, though trends in use of cocaine and crystal methamphetamine (CM), the two most commonly used unregulated stimulants in North America, are poorly characterized in many settings. In this study we examined patterns and associations between the injection of cocaine and CM over time in an urban Canadian setting.

METHODS

The study collected data from two prospective cohorts of people who inject drugs in Vancouver, Canada, between 2008 and 2018. We applied a time series analysis, using multivariable linear regression to detect relationships between reported CM and cocaine injection and year, controlling for covariates. The study used cross-correlation to evaluate the relative trajectories of each substance over time.

RESULTS

Among 2056 participants, per annum rates of reported injection cocaine use declined significantly over the duration of this study from 45 % to 18 % (p < 0.001), while rates of CM injection increased from 17 % to 32 % (p < 0.001). Multivariable linear regression showed that recent CM injection was negatively associated with recent cocaine injection (β = -0.609, 95 % CI = -0.750, -0.467). Cross-correlation demonstrated that injection CM use was associated with a decrease in the likelihood of cocaine injection 12 months later (p = 0.002).

CONCLUSIONS

These findings demonstrate an epidemiological shift in patterns of injection stimulant use, with rising CM injection associated with a corresponding decrease in cocaine injection over time. Strategies are urgently needed that help to treat and reduce harm among the growing population of people who inject CM.

Differential risks of syringe service program participants in Central Ohio: a latent class analysis

BACKGROUND

Significant heterogeneity exists among people who use drugs (PWUD). We identify distinct profiles of syringe service program (SSP) clients to (a) evaluate differential risk factors across subgroups and (b) inform harm reduction programming.

METHODS

Latent class analysis (LCA) was applied to identify subgroups of participants (N = 3418) in a SSP in Columbus, Ohio, from 2019 to 2021. Demographics (age, sex, race/ethnicity, sexual orientation, housing status) and drug use characteristics (substance[s] used, syringe gauge, needle length, using alone, mixing drugs, sharing supplies, reducing use, self-reported perceptions on the impact of use, and treatment/support resources) were used as indicators to define latent classes. A five-class LCA model was developed, and logistic regression was then employed to compare risk factors at program initiation and at follow-up visits between latent classes.

RESULTS

Five latent classes were identified: (1) heterosexual males using opioids/stimulants with housing instability and limited resources for treatment/support (16.1%), (2) heterosexual individuals using opioids with stable housing and resources for treatment/support (33.1%), (3) individuals using methamphetamine (12.4%), (4) young white individuals using opioids/methamphetamine (20.5%), and (5) females using opioids/cocaine (17.9%). Class 2 served as the reference group for logistic regression models, and at the time of entry, class 1 was more likely to report history of substance use treatment, overdose, HCV, sharing supplies, and mixing drugs, with persistently higher odds of sharing supplies and mixing drugs at follow-up. Class 3 was more likely to report history of overdose, sharing supplies, and mixing drugs, but outcomes at follow-up were comparable. Class 4 was the least likely to report history of overdose, HCV, and mixing drugs, but the most likely to report HIV. Class 5 was more likely to report history of substance use treatment, overdose, HCV, sharing supplies, and mixing drugs at entry, and higher reports of accessing substance use treatment and testing positive for HCV persisted at follow-up.

CONCLUSIONS

Considerable heterogeneity exists among PWUD, leading to differential risk factors that may persist throughout engagement in harm reduction services. LCA can identify distinct profiles of PWUD accessing services to tailor interventions that address risks, improve outcomes, and mitigate disparities.

Current attitudes toward drug checking services and a comparison of expected with actual drugs present in street drug samples collected from opioid users

BACKGROUND

The opioid epidemic continues to be associated with high numbers of fatalities in the USA and other countries, driven mainly by the inclusion of potent synthetic opioids in street drugs. Drug checking by means of various technologies is being increasingly implemented as a harm reduction strategy to inform users about constituent drugs in their street samples. We assessed how valued drug checking services (DCS) would be for opioid street drug users given the ubiquity of fentanyl and related analogs in the drug supply, the information they would most value from drug checking, and compared expected versus actual constituent drugs in collected samples.

METHODS

A convenience sample of opioid street drug users (N = 118) was recruited from two syringe service exchange programs in Chicago between 2021 and 2022. We administered brief surveys asking about overdose history, whether fentanyl was their preferred opioid, and interest in DCS. We also collected drug samples and asked participants what drug(s) they expected were in the sample. Provided samples were analyzed using LC-MS technology and the results compared to their expected drugs.

RESULTS

Participants reported an average of 4.4 lifetime overdoses (SD = 4.8, range = 0-20) and 1.1 (SD = 1.8, range = 0-10) past-year overdoses. A majority (92.1%) believed they had recently used drugs containing fentanyl whether intentionally or unintentionally. Opinions about the desirability of fentanyl were mixed with 56.1% indicating they did not and 38.0% indicating they did prefer fentanyl over other opioids, mainly heroin. Attitudes toward DCS indicated a general but not uniform receptiveness with a majority indicating interest in DCS though sizeable minorities believed DCS was "too much trouble" (25.2%) or there was "no point" in testing (35.4%). Participants were especially inaccurate identifying common cutting agents and potentiating drugs such as diphenhydramine in their samples (sensitivity = .17).

CONCLUSIONS

Results affirmed street drug users remain interested in using DCS to monitor their drugs and such services should be more widely available. Advanced checking technologies that provide information on the relative quantities and the different drugs present in a given sample available at point-of-care, would be most valuable but remain challenging to implement.

Understanding the rise in overdose deaths involving opioids and non-opioid prescription drugs in the United States

BACKGROUND

Previous studies demonstrate that the reformulation of OxyContin in the U.S. in 2010 induced substitution to illicit opioids, causing illicit opioid markets to grow disproportionately fast in states more exposed to the reformulation. In this paper, we examine if this shift to the illicit market also led to a rise in polysubstance overdose deaths involving non-opioid prescription drugs, including gabapentinoids and "Z-drugs" and, separately, benzodiazepines.

METHODS

Using a difference-in-differences framework, the relationship between exposure to reformulation and overdose death rates including specific substances was studied in each year from 1999 to 2020 while accounting for fixed differences across states, common nationwide shocks, and state-level differences in pain reliever misuse prior to reformulation. Exposure to reformulation was measured as the pre-reformulation rate of OxyContin misuse.

RESULTS

Exposure to reformulation predicted growth in overdose deaths involving gabapentinoids and Z-drugs. There is less evidence that it predicted growth in overdose deaths involving benzodiazepines. However, for all substances, there is strong evidence that pre-reformulation OxyContin misuse rates predicted post-reformulation growth in overdose deaths concurrently involving synthetic opioids.

DISCUSSION

The opioid crisis has changed in radical ways. This study links a major supply-side intervention to the increase in polysubstance overdose deaths involving non-opioid prescription drugs, specifically gabapentinoids and Z-drugs.

Prescription Drug Misuse with Alcohol Coingestion among US Adolescents: Youth Experiences, Health-related Factors, and Other Substance Use Behaviors

BACKGROUND

While alcohol use and prescription drug misuse (PDM) are common among adolescents, there is relatively little research on coingestion. This is disquieting as polysubstance use has become a major contributing factor in drug overdose deaths among young people in the United States.

METHODS

The current research uses multiple years of data from the National Survey on Drug Use and Health (2015-2019) to assess characteristics associated with coingestion among adolescents aged 12 to 17 years ( N = 57,352). Multinomial logistic regression analysis is used to identify characteristics associated with past 30-day PDM with and without alcohol coingestion. The primary objective is to determine how youth experiences with parents, involvement in conventional activities, religiosity, social support, and school status are associated with coingestion.

RESULTS

Among adolescents who report past 30-day PDM, 18.6% coingest with alcohol and 77.5% of adolescents who coingest report at least one substance use disorder. Several youth experiences were significantly associated with opioid coingestion including increased conflict with parents (relative risk ratio [RRR], 1.27; 95% confidence interval [CI], 1.07-1.48), lower levels of religiosity (RRR, 0.72; 95% CI, 0.52-0.98), less social support (RRR, 0.36; 95% CI, 0.18-0.69), and not being in school (RRR, 3.86; 95% CI, 1.33-11.17). In addition, emergency department visits, depression, and other substance use behaviors were also significantly associated with coingestion.

CONCLUSIONS

Findings demonstrate a strong connection between coingestion and substance use disorder among US adolescents. The findings from the current study can inform prevention and intervention efforts by identifying youth experiences and health-related factors that are associated with coingestion.

Evolving trends in drug overdose mortality in the USA from 2000 to 2020: an age-period-cohort analysis

Background

Drug overdose deaths in the USA have increased rapidly in the past 20 years, and understanding patterns and trends in mortality is essential to develop policy responses. This study aimed to determine whether cohort patterns in mortality due to drug overdose have changed in the past two decades and assess these patterns by race and sex.

Methods

The national records of accidental drug overdose death were extracted from Centers for Disease Control and Prevention, National Center for Health Statistics Mortality Data for 2000-2020. Age-period-cohort analysis was performed to examine independent effects of age, period and birth cohort on accidental drug overdose mortality.

Findings

The number of accidental drug overdose deaths increased by 622% between 2000 and 2020, and age-standardized mortality rates increased nearly four-fold in both men and women. Age-period-cohort decomposition found rapid increases in mortality since 2012 in men and women, with higher mortality risk in cohorts born after 1990. The fastest increase occurred in Black Americans since 2012, and Americans of all races born after 1975 had significantly higher mortality risk, with mortality risk increasing rapidly in more recent cohorts. The peak of mortality has shifted from the 40-59 age group to the 30-40 year age group in the past decade.

Interpretation

The burden of drug overdose mortality has shifted to younger Americans, and a new generation of Americans are at significantly higher and rapidly increasing risk of overdose death. Urgent action is needed to prevent an entire generation of young people being consigned to decades of preventable mortality.

Funding

None.

Associations between prescription stimulant use as prescribed, nonmedical use, and illicit stimulant use among adults evaluated for substance use treatment, 2017-2021

Background

Limited data exist on risk factors for illicit stimulant use, including associations between prescription stimulant use/nonmedical use (NMU) and illicit stimulant use.

Methods

We used 2017-2021 data from adults assessed for substance use disorder (SUD) treatment using the National Addictions Vigilance Intervention and Prevention Program Addiction Severity Index-Multimedia Version® tool. Multivariable Poisson regression models analyzed associations between past 30-day prescription stimulant use as prescribed or NMU and past 30-day illicit stimulant use. Separate models examined past 30-day illicit stimulant, methamphetamine, and cocaine use. We explored problem severity across seven biopsychosocial domains (e.g., drug, psychiatric, family) by past 30-day prescription stimulant use/NMU and illicit stimulant use.

Results

Among 218,981 assessments, 1.8% reported prescription stimulant NMU; 1.6% reported use as prescribed. Past 30-day prescription stimulant NMU (vs. no use) was associated with past 30-day illicit stimulant use (adjusted prevalence ratio [aPR] [95% CI]: 2.67 [2.59, 2.75]), methamphetamine use (aPR: 2.81 [2.71, 2.92]), and cocaine use (aPR: 3.53 [3.33, 3.74]). Prescription stimulant use as prescribed (vs. no use) was associated with lower prevalence of past 30-day illicit stimulant use. Assessments reporting prescription stimulant NMU (vs. no use, or use as prescribed) appeared more likely to have moderate-to-extreme problem scores across biopsychosocial domains, indicating greater need for treatment or assistance. Assessments reporting prescription stimulant use as prescribed or NMU frequently reported opioids, alcohol, or other substances as their primary substance problem.

Conclusions

Adults using illicit stimulants/nonmedically using prescription stimulants may benefit from care addressing polysubstance use, mental health, social, and recovery support services.

Feasibility study of using mobile phone-based experience sampling to assess drug checking by opioid street drug users

BACKGROUND

To date, evaluations of take-home fentanyl (and/or benzodiazepine) test strip use - the most common form of drug checking services - and potential effects on overdose risk have relied on retrospective accounts for some preceding time period, usually a week to several months. Such accounts, however, are subject to recall and memory biases. This pilot study assessed the feasibility of using experiential sampling to collect daily information in situ on drug checking and associated overdose risk reduction - the primary outcomes - among a sample of street opioid users and compared the results to retrospective reports.

METHODS

We recruited 12 participants from a Chicago-based syringe services program. Participants were 18 years of age or older, reported using opioids purchased on the street 3 + times per week in the past month, and had an available Android mobile phone. A phone-based app was programmed to collect daily drug checking information and provided to each participant along with a supply of fentanyl and benzodiazepine test strips and instructions for use over 21 days. Comparable retrospective data were collected via follow-up in-person surveys at the conclusion of daily report collection.

RESULTS

We found a reasonably high rate of daily reporting (63.5%) with participants submitting reports on 160 "person-days" out of 252 possible days. Participants submitted daily reports an average of 13 of 21 days. Reports of test strip use frequency varied between the retrospective and daily reports with a relatively higher percentage of days/time using test strips obtained from the daily reports. We also found higher proportions reporting overdose risk reduction behaviors on the daily reports compared with the retrospective reviews.

CONCLUSIONS

We believe the results support using daily experience sampling to collect information on drug checking behaviors among street drug users. Although resource intensive in comparison to retrospective reports, daily reporting potentially provides more detailed information on test strip use and its association with overdose risk reduction and, ultimately, fewer overdoses. Needed are larger trials and validation studies of daily experience sampling to identify the optimum protocol for collecting accurate information on drug checking and overdose risk reduction behavior.

Suspected Nonfatal Cocaine-Involved Overdoses Overall and With Co-involvement of Opioids

CONTEXT

The Centers for Disease Control and Prevention (CDC) developed a syndrome definition for detection of suspected nonfatal cocaine-involved overdoses. The definition can be used to monitor trends and detect anomalies in emergency department (ED) syndromic surveillance data at the national, state, and local levels.

OBJECTIVE

This study describes the development of the nonfatal, unintentional/undetermined intent cocaine-involved overdose (UUCOD) definition and analysis of trends over time.

DESIGN/SETTING

CDC developed the UUCOD definition to query ED data in CDC's National Syndromic Surveillance Program (NSSP). Data between 2018 and 2021 were analyzed from 29 states sharing data access in the Drug Overdose Surveillance and Epidemiology (DOSE) System via NSSP. Using Joinpoint regression, trends were analyzed for UUCOD overall, by sex and age group, and for UUCOD co-involving opioids.

MEASURES

Time trends between 2018 and 2021 were analyzed by examining average monthly percentage change. Individual trend segments and trend inflection points were analyzed by examining monthly percentage change.

RESULTS

During 2018-2021, a total of 27 240 UUCOD visits were identified by the syndrome definition. Analyses identified different patterns in trends for males and females, with largely similar trends for persons aged 15 to 44 years and 45 years or older. Analyses also identified seasonal patterns with increases in spring/summer months in UUCOD overall and UUCOD co-involving opioids and declines for both in fall/winter months.

CONCLUSION

This UUCOD syndrome definition will be useful for ongoing monitoring of suspected nonfatal overdoses involving cocaine and co-involving cocaine and opioids. Ongoing assessment of cocaine-involved overdose trends might identify anomalies requiring further investigation and inform deployment of resources.

Attitudes and experiences with fentanyl contamination of methamphetamine: exploring self-reports and urine toxicology among persons who use methamphetamine and other drugs

BACKGROUND

There are growing concerns about illicitly manufactured fentanyl (IMF) contamination of methamphetamine. This study aims to characterize the lay views and experiences with IMF-contaminated methamphetamine (IMF/meth) and identify participants with unknown IMF exposures through urine toxicology analysis.

METHODS

Between December-2019 and November-2021, structured interviews were conducted with 91 individuals who reported past 30-day use of methamphetamine and resided in Dayton, Ohio, USA. Lab-based urine toxicology analyses were conducted to identify fentanyl/analogs, methamphetamine, and other drugs. Bivariate analyses were conducted to identify characteristics associated with attitudes and experiences with IMF/meth, and unknown IMF exposures.

RESULTS

The majority (95.6%) of the study participants were non-Hispanic white, and 52.7% were female. Past 30-day use of methamphetamine was reported on a mean of 18.7 (SD 9.1) days, and 62.6% also reported past 30-day use of heroin/IMF. Most (76.9%) had a history of an unintentional drug-related overdose, but 38.5% rated their current risk for an opioid overdose as none. Besides fentanyl (71.9%), toxicology analysis identified nine fentanyl analogs/metabolites (e.g., 42.7% acetyl fentanyl, 19.0% fluorofentanyl, 5.6% carfentanil), and 12.4% tested positive for Xylazine. The majority (71.4%) believed that IMF/meth was common, and 59.3% reported prior exposures to IMF/meth. 11.2% tested positive for IMF but reported no past 30-day heroin/IMF use (unknown exposure to IMF). Views that IMF/meth was common showed association with homelessness (p = 0.04), prior overdose (p = 0.028), and greater perceived risk of opioid overdose (p = 0.019). Self-reported exposure to IMF/meth was associated with homelessness (p = 0.007) and obtaining take-home naloxone (p = 0.025). Individuals with unknown IMF exposure (test positive for IMF, no reported past 30-day heroin/IMF use) were older (49.9 vs. 41.1 years, p < 0.01), and reported more frequent past 30-day use of methamphetamine (24.4 vs. 18.0 days, p < 0.05). They indicated lower perceived risk of opioid overdose (0.1 vs. 1.9, scale from 0 = "none" to 4 = "high," p < 0.001).

DISCUSSION

This study suggests a need for targeted interventions for people who use methamphetamine and expansion of drug checking and other harm reduction services.

Substances from unregulated drug markets - A retrospective data analysis of customer-provided samples from a decade of drug checking service in Zurich (Switzerland)

BACKGROUND

Drug checking services (DCS) are harm reduction interventions for people who consume illicit substances. Unregulated drug markets lead to samples with unexpected and variable contents. A retrospective data analysis of Zurich's DCS was performed to determine the nature of these samples.

METHODS

This study aims to investigate the qualitative and quantitative properties of 16,815 customer-provided psychoactive drug samples analyzed chemically through the DCS in Zurich from 1^st January 2011 to 31^st December 2021. The main analytical method utilized for characterizing these substances was high-performance liquid chromatography and gas chromatography-mass spectrometry. Data sets are summarized using descriptive statistics.

RESULTS

There was a 2.5-fold increase in the number of tested samples over the past decade. An overall proportion of 57.9% (weighted mean) of samples within our database demonstrates unexpected analytical findings and additional low sample contents during the observation period. Substantial differences in quality and quantity between substance groups were detected and an increase of sample quality and content over time was demonstrated.

CONCLUSIONS

Chemical analysis reveals that over half of substances acquired from unregulated drug markets analyzed through DCS in Zurich are with low qualitative and quantitative properties, which may expose users to risks. Based on longitudinal analyses over a decade, this study contributes to the body of evidence that DCS may potentially manipulate unregulated drug markets towards providing better quality substances, as well as may stabilize these markets over time. The necessity for drug policy changes to make this service accessible in further settings was highlighted, as DCS still often take place in legal grey zones.

FUNDING

None to declare.

Feasibility Study of Using Mobile Phone-Based Experience Sampling to Assess Drug Checking by Opioid Street Drug Users

Background: To date, evaluations of take-home fentanyl (and/or benzodiazepine) test strip use - the most common form of drug checking services - and potential effects on overdose risk have relied on retrospective accounts for some preceding time period, usually a week to several months. Such accounts, however, are subject to recall and memory biases. This pilot study assessed the feasibility of using experiential sampling to collect daily information in situ on drug checking and associated overdose risk reduction - the primary outcomes - among a sample of street opioid users and compared the results to retrospective reports. Methods: We recruited 12 participants from a Chicago-based syringe services program. Participants were 18 years of age or older, reported using opioids purchased on the street 3+ times per week in the past month, and had an available Android mobile phone. A phone-based app was programmed to collect daily drug checking information and provided to each participant along with a supply of fentanyl and benzodiazepine test strips and instructions for use over 21 days. Comparable retrospective data were collected via follow-up in-person surveys at the conclusion of daily report collection. Results: We found a reasonably high rate of daily reporting (63.5%) with participants submitting reports on 160 "person-days" out of 252 possible days. Participants submitted daily reports an average of 13 of 21 days. Reports of test strip use frequency varied between the retrospective and daily reports with a relatively higher percentage of days/time using test strips obtained from the daily reports. We also found higher proportions reporting overdose risk reduction behaviors on the daily reports compared with the retrospective reviews. Conclusions: We believe the results support using daily experience sampling to collect information on drug checking behaviors among street drug users. Although resource intensive in comparison to retrospective reports, daily reporting potentially provides more detailed information on test strip use and its association with overdose risk reduction and, ultimately, fewer overdoses. Needed are larger trials and validation studies of daily experience sampling to identify the optimum protocol for collecting accurate information on drug checking and overdose risk reduction behavior.

A Dose of Truth: A Qualitative Assessment of Reactions to Messages about Fentanyl for People Who Use Drugs

Background: Fentanyl-related overdoses are occurring at alarming rates and developing campaigns to increase awareness about fentanyl and harm-reduction strategies is critical. A Dose of Truth is an educational campaign aiming to increase knowledge about the threat of fentanyl and risk of exposure among people who use drugs (PWUD). The current study tests preliminary concepts and messages for the campaign. Methods: Twenty-one one-on-one interviews were conducted with young adults ages 18-35 who use drugs. Participants discussed knowledge of fentanyl and perceived risk of exposure, and provided feedback on four concepts. Thematic analysis of transcripts generated insights about promising approaches and topics. Results: Findings demonstrated that fentanyl awareness is growing among PWUD, but they perceive low risk of exposure because they trust a source. Messaging that challenged that trust, by highlighting that contaminated drug supplies are increasingly widespread, made personal risk salient. Additionally, messaging conveyed through a personal narrative that encouraged carrying naloxone to protect friends was perceived as personally relevant. Conclusions: While opioid- and fentanyl-related campaigns exist, few have used an evidence-based process to guide campaign development. Addressing gaps in knowledge and developing messages that are personally relevant are foundational steps in creating effective campaigns on fentanyl and other substances.

Association of polysubstance use disorder with treatment quality among Medicaid beneficiaries with opioid use disorder

INTRODUCTION

The opioid crisis is transitioning to a polydrug crisis, and individuals with co-occurring substance use disorder (SUDs) often have unique clinical characteristics and contextual barriers that influence treatment needs, engagement in treatment, complexity of treatment planning, and treatment retention.

METHODS

Using Medicaid data for 2017-2018 from four states participating in a distributed research network, this retrospective cohort study documents the prevalence of specific types of co-occurring SUD among Medicaid enrollees with an opioid use disorder (OUD) diagnosis, and assesses the extent to which different SUD presentations are associated with differential patterns of MOUD and psychosocial treatments.

RESULTS

We find that more than half of enrollees with OUD had a co-occurring SUD, and the most prevalent co-occurring SUD was for "other psychoactive substances", indicated among about one-quarter of enrollees with OUD in each state. We also find some substantial gaps in MOUD treatment receipt and engagement for individuals with OUD and a co-occurring SUD, a group representing more than half of individuals with OUD. In most states, enrollees with OUD and alcohol, cannabis, or amphetamine use disorder are significantly less likely to receive MOUD compared to enrollees with OUD only. In contrast, enrollees with OUD and other psychoactive SUD were significantly more likely to receive MOUD treatment. Conditional on MOUD receipt, enrollees with co-occurring SUDs had 10 % to 50 % lower odds of having a 180-day period of continuous MOUD treatment, an important predictor of better patient outcomes. Associations with concurrent receipt of MOUD and behavioral counseling were mixed across states and varied depending on co-occurring SUD type.

CONCLUSIONS

Overall, ongoing progress toward increasing access to and quality of evidence-based treatment for OUD requires further efforts to ensure that individuals with co-occurring SUDs are engaged and retained in effective treatment. As the opioid crisis evolves, continued changes in drug use patterns and populations experiencing harms may necessitate new policy approaches that more fully address the complex needs of a growing population of individuals with OUD and other types of SUD.

Current Perspectives on Selective Dopamine D3 Receptor Antagonists/Partial Agonists as Pharmacotherapeutics for Opioid and Psychostimulant Use Disorders

Over three decades of evidence indicate that dopamine (DA) D3 receptors (D3R) are involved in the control of drug-seeking behavior and may play an important role in the pathophysiology of substance use disorders (SUD). The expectation that a selective D3R antagonist/partial agonist would be efficacious for the treatment of SUD is based on the following key observations. First, D3R are distributed in strategic areas belonging to the mesolimbic DA system such as the ventral striatum, midbrain, and ventral pallidum, which have been associated with behaviors controlled by the presentation of drug-associated cues. Second, repeated exposure to drugs of abuse produces neuroadaptations in the D3R system. Third, the synthesis and characterization of highly potent and selective D3R antagonists/partial agonists have further strengthened the role of the D3R in SUD. Based on extensive preclinical and preliminary clinical evidence, the D3R shows promise as a target for the development of pharmacotherapies for SUD as reflected by their potential to (1) regulate the motivation to self-administer drugs and (2) disrupt the responsiveness to drug-associated stimuli that play a key role in reinstatement of drug-seeking behavior triggered by re-exposure to the drug itself, drug-associated environmental cues, or stress. The availability of PET ligands to assess clinically relevant receptor occupancy by selective D3R antagonists/partial agonists, the definition of reliable dosing, and the prospect of using human laboratory models may further guide the design of clinical proof of concept studies. Pivotal clinical trials for more rapid progression of this target toward regulatory approval are urgently required. Finally, the discovery that highly selective D3R antagonists, such as R-VK4-116 and R-VK4-40, do not adversely affect peripheral biometrics or cardiovascular effects alone or in the presence of oxycodone or cocaine suggests that this class of drugs has great potential in safely treating psychostimulant and/or opioid use disorders.

History of the discovery, development, and FDA-approval of buprenorphine medications for the treatment of opioid use disorder

Buprenorphine-based medications were first approved by the United States Food and Drug Administration in 2002 for the treatment of opioid dependence, or opioid use disorder (OUD) as the condition is presently known. This regulatory milestone was the outcome of 36 years of research and development, which also led to the development and approval of several other new buprenorphine-based medications. In this short review, we first describe the discovery and early development stages of buprenorphine. Second, we review key steps that led to the development of buprenorphine as a drug product. Third, we explain the regulatory approval of several buprenorphine-based medications for the treatment of OUD. We also discuss these developments in the context of the evolution of regulations and policies that have progressively improved OUD treatment availability and efficacy, although challenges remain in removing system-level, provider-level, and local-level barriers to quality treatment, to integrating OUD treatment into routine care and other settings, to reducing disparities in access to treatment, and to optimizing person-centered outcomes.

Supply-side predictors of fatal drug overdose in the Washington/Baltimore HIDTA region: 2016-2020

BACKGROUND

Rising rates of fentanyl- and polydrug-involved drug overdose deaths have prompted inquiry into the role of drug supply in fatal overdose outcomes in the United States. To date, however, there have been few empirical investigations of drug enforcement strategies on fatal overdose rates, despite knowledge that both drug use and supply are often geographically distributed. To address this limitation, we examined measures of drug enforcement as predictors of next-year fatal overdose rates in the Washington/Baltimore High Intensity Drug Trafficking Area (W/B HIDTA).

METHODS

We conducted mixed-effects models to examine the role of drug seizures and disruption in drug trafficking organizations (DTOs) and money laundering organizations (MLOs) on fatal overdose rates over a 5-year period (2016-2020) across 45 local jurisdictions in the W/B HIDTA region. Outcomes included any, opioid-involved, and fentanyl-involved fatal overdose.

RESULTS

Adjusting for covariates, both the total number of drug seizures and amount of cocaine seized (in dosage units per capita) positively predicted next-year opioid- and fentanyl-involved fatal overdose rates. Disruption to DTO and MLO operations did not significantly predict next-year fatal overdose rates for any outcome.

CONCLUSION

Supply-side enforcement activities alone may have limited impact on reducing fatal overdose rates, but may serve as important markers to identify communities at high risk of fatal overdose and facilitate targeted intervention. Our findings underscore the importance of comprehensive law enforcement approaches that extend beyond drug enforcement to integrate prevention, linkage to treatment, and harm reduction strategies as needed to address the overdose epidemic.

Opioid agonist therapy engagement and crystal methamphetamine use: The impact of unregulated opioid use in Vancouver, Canada

BACKGROUND

Crystal methamphetamine use has substantially increased among people who use opioids in recent years, yet the impact of opioid agonist therapy (OAT) on crystal methamphetamine use remains poorly characterized. Therefore, we sought to examine the relationship between OAT engagement and crystal methamphetamine use and to assess if this relationship differs according to the ongoing use of unregulated opioids.

METHODS

Data was collected from two harmonized ongoing prospective cohorts of people who use drugs in Vancouver, Canada, between December 2005 and March 2020. We employed multivariable generalized estimating equations to study the relationship between OAT engagement and crystal meth use stratified by ongoing unregulated opioid use.

RESULTS

Of 1742 participants who reported frequent opioid use at baseline, the median age was 42 years, and 61.3% were male. Multivariable analyses showed that compared to those who had not received OAT for at least one year: in the absence of ongoing unregulated opioid use, individuals who recently discontinued (adjusted Odds Ratio [aOR] = 0.47, 95% CI = 0.27-0.79), newly initiated (aOR = 0.52, 95% CI = 0.31-0.89), or were retained on OAT (aOR = 0.48, 95% CI = 0.31-0.72) reported a lower frequency of crystal methamphetamine use; in the presence of ongoing unregulated opioid use, individuals who newly initiated OAT reported a greater crystal methamphetamine use frequency (aOR = 1.24, 95% CI = 1.02-1.51).

CONCLUSIONS

We demonstrated a differential relationship between OAT engagement and crystal methamphetamine use that was conditional on the ongoing use of unregulated opioids. Our findings highlight the complexity of OAT implementation and suggest that polysubstance use patterns should be an important consideration for care providers when devising comprehensive treatment strategies and prognosticating treatment effects.

Proliferation of Novel Synthetic Opioids in Postmortem Investigations After Core-Structure Scheduling for Fentanyl-Related Substances

ABSTRACT

New generations of novel synthetic opioids (NSOs) have emerged to fill a void in the illicit drug markets left by the decline in popularity of fentanyl analogs subsequent to core-structure scheduling of fentanyl-related substances in the United States and China. These new opioids include members of the 2-benzyl benzimidazole (eg, isotonitazene, metonitazene, N -pyrrolidino etonitazene, protonitazene, etodesnitazene), benzimidazolone (eg, brorphine), and cinnamylpiperazine (eg, AP-238, 2-methyl AP-237) subclasses. Novel synthetic opioids continue to be detected in opioid-related fatal overdoses, demonstrating the harms associated with exposure to these drugs. Between January 2020 and December 2021, 384 casework blood samples were reported by our laboratory to contain 1 or more of the prior listed 8 NSOs. Isotonitazene (n = 144), metonitazene (n = 122), and brorphine (n = 91) were the 3 most prevalent substances, with positivity for isotonitazene and brorphine peaking just before the announcement of emergency scheduling. These NSOs have been documented as significant drivers of drug mortality, and this case series described here highlights the challenges medical examiners and coroners face in staying current with emerging drugs. Challenges include regional differences, rapid turnover, short lifecycles, variable toxicology testing, and difficulty in assessing individual drug toxicity in polydrug cases.

Buprenorphine exposure levels to optimize treatment outcomes in opioid use disorder

The severity of the ongoing opioid crisis, recently exacerbated by the COVID-19 pandemic, emphasizes the importance for individuals suffering from opioid use disorder (OUD) to have access to and receive efficacious, evidence-based treatments. Optimal treatment of OUD should aim at blocking the effects of illicit opioids while controlling opioid craving and withdrawal to facilitate abstinence from opioid use and promote recovery. The present work analyses the relationship between buprenorphine plasma exposure and clinical efficacy in participants with moderate to severe OUD using data from two clinical studies (39 and 504 participants). Leveraging data from placebo-controlled measures assessing opioid blockade, craving, withdrawal and abstinence, we found that buprenorphine plasma concentrations sustained at 2-3 ng/ml (corresponding to ≥70% brain mu-opioid receptor occupancy) optimized treatment outcomes in the majority of participants, while some individuals (e.g., injecting opioid users) needed higher concentrations. Our work also included non-linear mixed effects modeling and survival analysis, which identified a number of demographic, genetic and social factors modulating treatment response and retention. Altogether, these findings provide key information on buprenorphine plasma levels that optimize clinical outcomes and increase the likelihood of individual treatment success. NLM identifiers: NCT02044094, NCT02357901.

Predictors of crystal methamphetamine use initiation or re-initiation among people receiving opioid agonist therapy: A prospective cohort study

BACKGROUND

In the context of the ongoing opioid crisis in the United States and Canada, opioid agonist therapy (OAT) is the first-line treatment for opioid use disorder. However, there is growing concern regarding the increasing methamphetamine use among those on OAT, as well as the impact of such use may have on OAT retention and outcomes. We sought to identify the predictors of crystal methamphetamine initiation or re-initiation among people on OAT, in order to facilitate the development of effective preventive strategies.

METHODS

We employed multivariable generalized estimating equations to identify the predictors of crystal methamphetamine use initiation or re-initiation among those who were on OAT within two prospective cohorts in Vancouver, Canada between 2005 and 2020.

RESULTS

Of the 1281 participants receiving OAT, the median age was 43 years, and 59.2 % were male at baseline. During study follow-up, 564 (44.0 %) initiated or re-initiated crystal methamphetamine use while receiving OAT. In a multivariable model, a higher crystal methamphetamine use initiation or re-initiation rate was positively associated with younger age, unstable housing, unprotected sex, history of crystal methamphetamine use, as well as recent cocaine, prescription opioid, and unregulated opioid use (all p < 0.05).

CONCLUSIONS

We identified high and increasing rates of crystal methamphetamine use initiation or re-initiation among our sample of people on OAT. Intervention strategies including housing program referral, sexual risk reduction, and integrated treatment approaches targeting polysubstance use are urgently needed to reduce the risks associated with methamphetamine use as well as the co-use of methamphetamine and opioids.

Characteristics and correlates of fentanyl preferences among people with opioid use disorder

OBJECTIVES

Fentanyl has come to dominate the U.S. illicit opioid supply. We aimed to characterize and examine correlates of preferences for fentanyl vs. other opioids among individuals starting OUD treatment.

METHODS

We interviewed 250 adults initiating buprenorphine treatment with positive fentanyl toxicology at intake. We characterized opioid preferences and examined bivariate associations between opioid preference (preference for heroin, fentanyl, heroin-fentanyl mix, or other opioid) and sociodemographic characteristics, psychosocial factors, and substance use behaviors. We then used multinomial logistic regression to examine factors independently associated with fentanyl preferences.

RESULTS

Over half (52.0 %) of participants preferred fentanyl (21.2 % fentanyl alone, 30.8 % heroin-fentanyl mix). In bivariate comparisons, participants who preferred fentanyl were a higher acuity group with respect to risks and problems in general. In the multinomial logistic regression, people who preferred fentanyl, either alone or mixed with heroin, used non-prescribed buprenorphine less in the 30 days preceding treatment entry compared to people who preferred heroin or other opioids (RRRalone= 0.88 [0.78, 0.99]; P = 0.037 and RRRmixed= 0.91 [0.84, 0.99]; P = 0.046). People who preferred fentanyl alone were also younger (RRR= 0.93 [0.90, 0.97]; P < 0.001) and more likely to have severe mental illness (RRR= 2.5 [1.1, 5.6]; P = 0.027) than people who prefer heroin or other opioids.

CONCLUSIONS

Many people with OUD report preferring fentanyl. People who express preference for fentanyl differ substantively from those with other opioid preferences, and may be at elevated risk for poor health outcomes. Understanding preferences surrounding fentanyl could inform treatment and harm reduction interventions.

A randomized, sham-controlled, quintuple-blinded trial to evaluate the NET device as an alternative to medication for promoting opioid abstinence

Background

There is an unmet need for non-medication approaches to illicit opioid discontinuation and relapse prevention. The NET (NeuroElectric Therapy) Device is a non-invasive, battery-operated, portable, re-useable device designed to deliver bilateral transcranial transcutaneous alternating current electrical stimulation, and is intended to treat opioid use disorder (OUD) without medication. The device is a CE-marked Class IIa, non-significant risk, investigational medical device.

Objective

This prospective trial (NRC021) tests the hypothesis that the NET Device provides safe and effective neurostimulation treatment for persons with OUD who express a desire to be opioid abstinent without medications for opioid use disorder (MOUD).

Methods

NRC021 is a randomized, parallel-group, sham-controlled, quintuple-blinded, single-site study. Persons with OUD entering a residential treatment facility for opioid detoxification are assigned to active or sham treatment (n = 50/group). Group assignment is stratified on presence of any current non-opioid substance use disorder and by sex. The biostatistician maintains the blinding so that the study sponsor, principal investigator, research assistants, treatment staff, and participants remain blinded. Following discharge from the inpatient facility, participants are assessed once weekly over 12 weeks for substance use (using timeline followback interview and video assessment of observed oral fluid sample provision and testing). The primary efficacy endpoint is each participant's overall percentage of weekly abstinence from illicit opioid use without use of MOUD. The secondary efficacy endpoint is each participant's percentage of non-opioid drug-free weeks. Safety outcomes are also measured.

Conclusion

NRC021 is designed to assess the efficacy of a novel non-medication treatment for OUD.

Clinical trial registration

ClinicalTrials.gov with the identifier NCT04916600.

Twenty-year trends in pharmaceutical fentanyl and illicit fentanyl deaths, Australia 2001-2021

BACKGROUND

Increasing overdose deaths attributable to illicitly manufactured fentanyl and fentanyl analogues in North America has driven international concern about the expansion of these substances into drug markets elsewhere. This paper investigates 20-year trends in fentanyl deaths in Australia, distinguishing between deaths attributable to pharmaceutical, and to illicitly manufactured fentanyl and fentanyl analogues.

METHODS

Analysis of fentanyl overdose deaths (2001-2021), extracted from the National Coronial Information System (NCIS).

RESULTS

833 fentanyl-related deaths were identified, predominantly occurring among males (73%), and people with a history of injecting drug use (67%). Rates of fentanyl deaths significantly increased between 2001 and 2014 and declined between 2015 and 2021. Drug dependence remained the most significant factor in deaths among people with a history of injecting drug use (87% vs 23% without such a history), while having died by suicide was the most significant factor for those without a history of injecting drug use (20% vs 4% respectively). Three quarters (72%) of deaths were attributable to pharmaceutical fentanyl and 21% to probable pharmaceutical fentanyl, with 5% attributable to fentanyl analogues (3%) (predominantly furanylfentanyl and acetylfentanyl) and illicitly manufactured fentanyl (2%). Deaths attributable to illicitly manufactured fentanyl and fentanyl analogues occurred from 2013 onwards.

CONCLUSION

Pharmaceutical fentanyl deaths in Australia have declined since 2015, in parallel with overall declines in pharmaceutical opioids (including fentanyl) dispensed since 2014. Deaths continue to occur among people with a history of injecting drug use and drug dependence. Deaths attributable to illicit fentanyl have emerged since 2013 but remain low in comparison to pharmaceutical fentanyl deaths.

Association of multidisciplinary education and research in substance use and addiction's (AMERSA) 2021 transforming care through evidence and policy conference: Tackling stigma and giving voice to lived experience

This commentary provides an overview of the Association of Multidisciplinary Education and Research in Substance use and Addiction (AMERSA) 2021 annual conference: Transforming Care Through Evidence and Policy. The topics covered during the conference were especially critical given the unprecedented rise in drug overdose deaths and continued impact of the COVID-19 pandemic on substance use and addiction. The importance of tackling stigma and ensuring that we partner with those with lived experience to have maximal impact was highlighted.

Opioid-stimulant trends in overdose toxicology by race, ethnicity, & gender: An analysis in Delaware, 2013-2019

Recent upticks of stimulant presence in overdose deaths suggest the opioid epidemic is morphing, which raises questions about what drugs are involved and who is impacted. We investigate annual and growth rate trends in combined opioid-stimulant overdose toxicology between 2013 and 2019 for White, Black, and Hispanic male and female decedents in Delaware. During these years, toxicology shifted to illegal drugs for all with fentanyl leading the increase and opioid-cocaine combinations rising substantially. While combined opioid-cocaine toxicology grew among Black and Hispanic Delawareans, White males continue to report the highest rates overall. These findings depart from historical patterns and may challenge existing opioid epidemic policies.

6-Monoacetylmorphine-antibody distribution in tissues from heroin-related death cases: An experimental study to investigate the distributive response

Heroin, a semisynthetic opioid drug synthesized from morphine, is the 3,6-diacetyl ester of morphine (diacetylmorphine). The post-mortem diagnosis of heroin-related death could be an issue and usually rely on a combination of investigations, including the autopsy, histological and toxicological analysis. We conducted the present study to evaluate the correlation between the heroin concentration in biological fluids (peripheral blood, bile and urine) and the post-mortem anti-6-MAM antibody expression in various tissues (brain, heart, lung, liver and kidney) using immunohistochemical staining. A quantitative analysis of the immunohistochemical reaction was carried out. 45 cases of heroin-related death investigated at the Forensic Pathology Institutes of the University of Rome, Foggia and Pisa were included. The control group was composed of 15 cases of death due to other causes, without brain lesions and negative toxicological analysis for drugs. We found a positive immunohistochemical reaction in different organs and it was related to the timing of heroin metabolization. No reaction was found in the control group. Our findings show that immunohistochemistry can be a valuable tool for the post-mortem diagnosis of acute heroin abuse. A better understanding of the timing of heroin's metabolism can be useful in the forensic field and for future therapeutic applications.