The epidemic of fentanyl misuse and overdoses: challenges and strategies

"I don't want it in any form:" A qualitative study on black perceptions of buprenorphine in the fentanyl era

BACKGROUND

The current phase of the US opioid overdose epidemic is marked by growing racial inequities, driven in part by unequal access to medications for opioid use disorder (MOUD) including buprenorphine. This report provides a much needed update on the racialized patterns of treatment uptake in an evolving drug use and treatment landscape.

METHODS

We conducted semi-structured qualitative interviews with 28 African American people with a self-reported history of OUD who had lived in the Twin Cities (Minneapolis and Saint Paul), Minnesota for at least a year. Interviews explored participants' attitudes, knowledge, and perceptions of medications for OUD (MOUD) with a focus on methadone and buprenorphine.

FINDINGS

67.9 % of participants were male and the mean age was 53.4. More participants knew about and had taken methadone (100 %, 89.3 %, respectively) as compared to buprenorphine (89.3 %, 75 % respectively). We identified three key themes: 1) the unfamiliarity of buprenorphine; 2) the remembered damage of buprenorphine-induced precipitated withdrawal; and 3) readiness to quit and its impact on medication choice.

CONCLUSIONS

Black perceptions of MOUD consist of universally dim views toward methadone and highly ambiguous attitudes toward buprenorphine. Strategies to improve Black access to buprenorphine must therefore be grounded in a better understanding of the historical context of MOUDs in this community and the medical mistrust it engenders. Better strategies for safe induction of people with fentanyl dependence are also needed, particularly those informed by the concerns and priorities of Black and other racially minoritized communities.

The therapeutic effects of psychedelics for opioid use disorder: A systematic review of clinical studies

Opioid-related overdose deaths have reached record high levels, and novel treatments for opioid use disorder (OUD) are needed. The three United States Food and Drug Administration (FDA)-approved medications for OUD function primarily at the mu-opioid receptor. While these remain the gold-standard treatment for OUD, they have shortcomings and treatment options separate from the opioid receptor system deserve attention. Preclinical, clinical, and naturalistic studies of psychedelics have shown some evidence that they may reduce opioid and other substance use. Here, we present the results of a systematic review of clinical studies investigating the therapeutic applications of psychedelics for OUD to describe the current state of the literature and guide future clinical study design in this area. Findings indicate few studies completed using serotonergic psychedelics, with most investigating ibogaine or ketamine. In addition, findings are limited by many studies of weak design focused on opioid withdrawal, and few double-blind or placebo-controlled trials with considerable methodological heterogeneity making comparisons difficult across compounds. Most studies were found to have a high risk of bias mostly related to lack of randomization, blinding, and blinding of assessment outcomes. We outline these limitations and steps towards improving the quality of future studies of psychedelics for OUD.

The development of opioid vaccines as a novel strategy for the treatment of opioid use disorder and overdose prevention

Opioid use disorder (OUD) affects over 40 million people worldwide, creating significant social and economic burdens. Medication for opioid use disorder (MOUD) is often considered the primary treatment approach for OUD. MOUD, including methadone, buprenorphine, and naltrexone, is effective for some, but its benefits may be limited by poor adherence to treatment recommendations. Immunopharmacotherapy offers an innovative approach by using vaccines to generate antibodies that neutralize opioids, blocking them from crossing the blood-brain barrier and reducing their psychoactive effects. To date, only 3 clinical trials for opioid vaccines have been published. While these studies demonstrated the potential of opioid vaccines for relapse prevention, there is currently no standardized protocol for evaluating their effectiveness. We have reviewed recent preclinical studies that demonstrated the efficacy of vaccines targeting opioids, including heroin, morphine, oxycodone, hydrocodone, and fentanyl. These studies showed that vaccines against opioids reduced drug reinforcement, decreased opioid-induced antinociception, and increased survival rates against lethal opioid doses. These studies also demonstrated the importance of vaccine formulation and the use of adjuvants in enhancing antibody production and specificity. Finally, we highlighted the strengths and concerns associated with the opioid vaccine treatment, including ethical considerations.

Capturing the Full Range of Buprenorphine Treatment Response

Importance

Reliance on abstinence-based treatment success rules may fail to capture the full continuum of treatment response to buprenorphine plus medical counseling (BUP+MC) for opioid use disorder (OUD).

Objective

To describe patterns of reduction in illicit opioid use of patients both labeled as a success and nonsuccess based on an abstinent-based treatment outcome rule.

Design, Setting, and Participants

This study is a secondary data analysis of 4 harmonized randomized clinical trials on BUP+MC for OUD from multiple sites that included 869 patients with OUD. These data were analyzed on April 23, 2024. By week 12, 643 participants of the sample original remained (74%).

Intervention

All studies included patients randomized to BUP+MC or BUP plus enhanced MC (eg, delivered with adjunctive cognitive behavioral therapy).

Main Outcomes and Measures

Weekly self-reported days of illicit opioid use through 12 weeks of treatment. Abstinence was confirmed by urine drug screen.

Results

This study included 869 adults with OUD aged 18 to 69 (mean, 34.2 [SD, 10.45]) years; 287 patients were female (33%), 52 identified as Black (6%), 70 identified Hispanic (8%), 713 identified as White (82%), and 34 identified as other racial groups (4%). Only 377 patients (43%) would have been labeled a success using an abstinence-based success rule. However, the total sample reported a decrease from a mean baseline rate of illicit opioid use nearly every day (6.21 [SD, 1.50] days per week) to a mean of less than 1 day per week at week 12 (0.54 [SD, 1.28]). Importantly, even those who were labeled as nonsuccessful reported a substantial reduction in opioid use from a mean of 6.29 (SD, 1.42) days per week to 1.51 (SD, 1.76) days per week.

Conclusion and Relevance

In this study, about half of patients receiving BUP+MC achieved near complete abstinence; however, many more experienced a partial treatment response characterized by a substantial reduction in illicit opioid use that falls short of abstinence. Future studies are needed to characterize how these reductions are associated with functional and long-term outcomes. Dissemination of BUP+MC as part of standard buprenorphine prescribing practices is an essential next step given the robust average response of this intervention.

Time Course of Reversal of Fentanyl-Induced Respiratory Depression in Healthy Subjects by Intramuscular Nalmefene and Intramuscular and Intranasal Naloxone

The increase in opioid overdose deaths, particularly involving potent, long-acting synthetic opioids, has led to calls for stronger, longer-acting opioid-overdose-reversal agents. Using an opioid-induced respiratory depression model, we investigated the onset and time course of action of naloxone and a long-acting opioid antagonist, nalmefene, in reversing the effects of an ongoing intravenous fentanyl infusion over a period of up to 100 min. Healthy, moderately experienced opioid users received intramuscular (IM) nalmefene 1 mg, IM naloxone 2 mg, or intranasal (IN) naloxone 4 mg after fentanyl-induced respiratory depression was established based on reduction in respiratory minute volume (MV). Each participant received each opioid antagonist twice per a randomized crossover schedule. Reversal of respiratory depression, pharmacokinetics, and safety were investigated. Participants showed rapid increases in plasma opioid antagonist concentrations, and meaningful reversal of depressed MV tended to occur earlier with IM nalmefene and IM naloxone than with IN naloxone. Compared to naloxone, nalmefene provided extended exposure, and mean MV was maintained at a higher level. All participants experienced treatment-related adverse events, but none were severe, serious, or led to study drug discontinuation. This study provides evidence that IM nalmefene 1 mg achieves reversal of fentanyl-induced respiratory depression similar to or better than that achieved with standard-of-care naloxone treatments. No new safety concerns were raised for IM nalmefene at the tested dose. The pharmacokinetic and pharmacodynamic properties of IM nalmefene position it as an important treatment option in opioid overdose reversal, particularly given the increasing prevalence of overdoses involving potent, long-acting synthetic opioids.

Evolution of the substance use landscape: Implications for contingency management

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

A place-based spatial analysis of racial inequities in overdose in St. Louis County Missouri, United States

OBJECTIVE

The objective of this study was to identify place features associated with increased risk of drug-involved fatalities and generate a composite score measuring risk based on the combined effects of features of the built environment.

METHODS

We conducted a geospatial analysis of overdose data from 2022 to 2023 provided by the St. Louis County Medical Examiner's Office to test whether drug-involved deaths were more likely to occur near 54 different place features using Risk Terrain Modeling (RTM). RTM was used to identify features of the built environment that create settings of heightened overdose risk. Risk was estimated using Relative Risk Values (RRVs) and a composite score measuring Relative Risk Scores (RRS) across the county was produced for drugs, opioids, and stimulants, as well as by Black and White decedents.

RESULTS

In the model including all drugs, deaths were more likely to occur in close proximity to hotels/motels (RRV=39.65, SE=0.34, t-value=10.81 p<.001), foreclosures (RRV=4.42, SE=0.12, t-value = 12.80, p<.001), police departments (RRV=3.13, SE=0.24, t-score=4.86, p<.001), and restaurants (RRV=2.33, SE=0.12, t-value=7.16, p<.001). For Black decedents, deaths were more likely to occur near foreclosures (RRV=9.01, SE=0.18, t-value =11.92, p<.001), and places of worship (RRV= 2.51, SE=0.18, t-value = 11.92, p<.001). For White decedents, deaths were more likely to occur in close proximity to hotels/motels (RRV=38.97, SE=0.39, t-value=9.30, p<.001) foreclosures (RRV=2.57, SE=0.16, t-value =5.84, p<.001), restaurants (RRV=2.52, SE=0.17, t-value=5.33, p<.001) and, auto painting/repair shops (RRV=0.04, SE=0.18, t-value =3.39, p<.001).

CONCLUSION

These findings suggest that places of worship, the hospitality industry, and housing authorities may be physical features of the environment that reflect social conditions that are conducive to overdose. The scaling up of harm reduction strategies could be enhanced by targeting places where features are co-located.

Leveraging Implementation Factors and Policy to Improve the Effectiveness of Naloxone

ABSTRACT

More than 50 years of high-quality data demonstrate that naloxone is an efficacious and cost-effective overdose reversal agent. Intranasal naloxone is now available in the United States as an over-the-counter and generic medication for the first time since the start of the overdose crisis more than 20 years ago. As the overdose crisis continues to contribute to substantial loss of life, there is an historic opportunity for jurisdictions to expand equitable and sustained access to intranasal naloxone. Further, through simultaneously enacting and expanding effective Naloxone Access and Good Samaritan laws, and equitably implementing these laws, there is the potential to maximize the population-level effectiveness of naloxone to sustainably reduce overdose mortality.

Medial prefrontal neuroplasticity during extended-release naltrexone treatment of opioid use disorder - a longitudinal structural magnetic resonance imaging study

Opioid use disorder (OUD) has been linked to macroscopic structural alterations in the brain. The monthly injectable, extended-release formulation of μ-opioid antagonist naltrexone (XR-NTX) is highly effective in reducing opioid craving and preventing opioid relapse. Here, we investigated the neuroanatomical effects of XR-NTX by examining changes in cortical thickness during treatment for OUD. Forty-seven OUD patients underwent structural magnetic resonance imaging and subjectively rated their opioid craving ≤1 day before (pre-treatment) and 11 ± 3 days after (on-treatment) the first XR-NTX injection. A sample of fifty-six non-OUD individuals completed a single imaging session and served as the comparison group. A publicly available [¹¹C]carfentanil positron emission tomography dataset was used to assess the relationship between changes in cortical thickness and μ-opioid receptor (MOR) binding potential across brain regions. We found that the thickness of the medial prefrontal and anterior cingulate cortices (mPFC/aCC; regions with high MOR binding potential) was comparable between the non-OUD individuals and the OUD patients at pre-treatment. However, among the OUD patients, mPFC/aCC thickness significantly decreased from pre-treatment to on-treatment. A greater reduction in mPFC/aCC thickness was associated with a greater reduction in opioid craving. Taken together, our study suggests XR-NTX-induced cortical thickness reduction in the mPFC/aCC regions in OUD patients. The reduction in thickness does not appear to indicate a restoration to the non-OUD level but rather reflects XR-NTX's distinct therapeutic impact on an MOR-rich brain structure. Our findings highlight the neuroplastic effects of XR-NTX that may inform the development of novel OUD interventions.

Induction to Methadone 80 mg in the First Week of Treatment of Patients Who Use Fentanyl: A Case Series From an Outpatient Opioid Treatment Program

OBJECTIVES

Current guidelines for methadone titration may unnecessarily delay reaching effective doses for patients using fentanyl, resulting in an increased risk of ongoing fentanyl use, dissatisfaction with treatment, and early dropout. Development and evaluation of rapid methadone induction protocols may improve treatment for patients using fentanyl.

METHODS

Retrospective chart review was conducted for patients admitted in 2022 to a single licensed opioid treatment program (OTP) where a rapid induction protocol provides methadone 40 mg on day 1, 60 mg on day 2, and 80 mg on day 3 to patients using fentanyl <65 years old without significant medical comorbidities. The primary feasibility outcome was completion of the protocol, defined by receipt of methadone dose 80 mg or more on treatment day 7. The primary safety outcomes were oversedation, nonfatal overdose, and death. A secondary outcome was retention in treatment at 30 days.

RESULTS

Rapid induction was ordered for 93 patients and completed by 65 (70%). Average dose on day 7 for patients who completed was 89 mg (SD 9.5 mg) versus 49 mg (SD 14.0 mg) for those who did not. No episodes of oversedation, nonfatal overdose, or death were observed. At 30 days, 85% of the patients who had the rapid protocol ordered (79/93) were retained, with 88% (57/65) who completed the protocol retained versus 79% (22/28) who did not complete (OR 1.9, 95% CI 0.6-6.2).

CONCLUSIONS

Rapid induction to methadone 80 mg by day 7 was feasible for outpatients using fentanyl in this study at a single OTP. No significant safety events were identified.

False-Positive Rate for Suspected Drug-Related Deaths Following Full Autopsy

ABSTRACT

The sharp increase in drug-related deaths has tempted medical examiner/coroner offices to perform external examinations with comprehensive toxicology testing instead of performing a standard autopsy. Compounding the problem of an increasing workload has been the decrease in available forensic pathologists. Opting for external examinations on suspected drug-related fatalities, however, is antithetical to current best practices. The purpose of this study was to review case files, autopsy reports, and toxicologic results of all deaths that were autopsied at the authors' facility and decide whether significant disease processes or injuries that would supersede the results of toxicologic testing and external examination findings alone were being missed.

Searching for Synthetic Opioid Rescue Agents: Identification of a Potent Opioid Agonist with Reduced Respiratory Depression

While in the process of designing more effective synthetic opioid rescue agents, we serendipitously identified a new chemotype of potent synthetic opioid. Here, we report that conformational constraint of a piperazine ring converts a mu opioid receptor (MOR) antagonist into a potent MOR agonist. The prototype of the series, which we have termed atoxifent (2), possesses potent in vitro agonist activity. In mice, atoxifent displayed long-lasting antinociception that was reversible with naltrexone. Repeated dosing of atoxifent produced antinociceptive tolerance and a level of withdrawal like that of fentanyl. In rats, while atoxifent produced complete loss of locomotor activity like fentanyl, it failed to produce deep respiratory depression associated with fentanyl-induced lethality. Assessment of brain biodistribution demonstrated ample distribution of atoxifent into the brain with a Tmax of approximately 0.25 h. These results indicate enhanced safety for atoxifent-like molecules compared to fentanyl.

Acceptability and anticipated effectiveness of a safe supply of opioids, among people who inject opioids in King County, WA

BACKGROUND

Opioid overdose mortality in the US has exceeded one million deaths over the last two decades. A regulated opioid supply may help prevent future overdose deaths by reducing exposure to the unregulated opioid supply. We examined the acceptability, delivery model preference, and anticipated effectiveness of different regulated opioid models among people in the Seattle area who inject opioids.

METHODS

We enrolled people who inject drugs in the 2022 Seattle-area National HIV Behavior Surveillance (NHBS) survey. Participants were recruited between July and December 2022 using respondent-driven sampling. Participants who reported injecting opioids (N = 453) were asked whether regulated opioids would be acceptable, their preferred model of receiving regulated opioids, and the anticipated change in individual overdose risk from accessing a regulated opioid supply.

RESULTS

In total, 369 (81 %) participants who injected opioids reported that a regulated opioid supply would be acceptable to them. Of the 369 who found a regulated opioid supply to be acceptable, the plurality preferred a take-home model where drugs are prescribed (35 %), followed closely by a dispensary model that required no prescription (28 %), and a prescribed model where drugs need to be consumed on site (13 %), a model where no prescription is required and drugs can be accessed in a community setting with a one-time upfront payment was the least preferred model (5 %). Most participants (69 %) indicated that receiving a regulated opioid supply would be "a lot less risky" than their current supply, 20 % said, "a little less risky", 10 % said no difference, and 1 % said a little or a lot more risky.

CONCLUSION

A regulated opioid supply would be acceptable to most participants, and participants reported it would greatly reduce their risk of overdose. As overdose deaths continue to increase in Washington state pragmatic and effective solutions that reduce exposure to unregulated drugs are needed.

Simulating the Simultaneous Impact of Medication for Opioid Use Disorder and Naloxone on Opioid Overdose Death in Eight New York Counties

BACKGROUND

The United States is in the midst of an opioid overdose epidemic; 28.3 per 100,000 people died of opioid overdose in 2020. Simulation models can help understand and address this complex, dynamic, and nonlinear social phenomenon. Using the HEALing Communities Study, aimed at reducing opioid overdoses, and an agent-based model, Simulation of Community-Level Overdose Prevention Strategy, we simulated increases in buprenorphine initiation and retention and naloxone distribution aimed at reducing overdose deaths by 40% in New York Counties.

METHODS

Our simulations covered 2020-2022. The eight counties contrasted urban or rural and high and low baseline rates of opioid use disorder treatment. The model calibrated agent characteristics for opioid use and use disorder, treatments and treatment access, and fatal and nonfatal overdose. Modeled interventions included increased buprenorphine initiation and retention, and naloxone distribution. We predicted a decrease in the rate of fatal opioid overdose 1 year after intervention, given various modeled intervention scenarios.

RESULTS

Counties required unique combinations of modeled interventions to achieve a 40% reduction in overdose deaths. Assuming a 200% increase in naloxone from current levels, high baseline treatment counties achieved a 40% reduction in overdose deaths with a simultaneous 150% increase in buprenorphine initiation. In comparison, low baseline treatment counties required 250-300% increases in buprenorphine initiation coupled with 200-1000% increases in naloxone, depending on the county.

CONCLUSIONS

Results demonstrate the need for tailored county-level interventions to increase service utilization and reduce overdose deaths, as the modeled impact of interventions depended on the county's experience with past and current interventions.

Parenteral, Non-Intravenous Analgesia in Acute Traumatic Pain-A Narrative Review Based on a Systematic Literature Search

Traumatic pain is frequently encountered in emergency care and requires immediate analgesia. Unfortunately, most trauma patients report sustained pain upon arrival at and discharge from the Emergency Department. Obtaining intravenous access to administer analgesics can be time-consuming, leading to treatment delay. This review provides an overview of analgesics with both fast onset and parenteral, non-intravenous routes of administration, and also indicates areas where more research is required.

Safety of electroconvulsive therapy (ECT) in pregnancy: a systematic review of case reports and case series

Pregnancy and the immediate postpartum period are considered at high risk for women who have already received a previous psychiatric diagnosis and might represent a stressful event favoring the onset of new psychiatric disorders. The electroconvulsive therapy (ECT) is effective for the treatment of severe, treatment-resistant mental disorders, and it could represent a therapeutic choice for psychiatric conditions during pregnancy. The purpose of this systematic review is to evaluate the safety of ECT during pregnancy and to update the state of the art of its use. An extensive literature search on PubMed, APA PsycInfo, and Scopus databases for relevant articles published from inception to September 2023 has been performed. A final number of 45 articles (34 case reports and 11 case series, for a total of 130 pregnant women) were included in the present review. The limited evidence confirmed that ECT is effective in determining a partial remission of symptoms in women suffering from severe mental disorders, especially in the presence of suicidal ideation or psychosis, during all pregnancy epochs. However, ECT is not free from side effects, although the majority of possible complications were of low- or moderate-grade and not life-threatening for the women. Exposure to pharmacological treatment before or during the ECT or to the anesthetic during ECT might have contributed to the onset of these complications. ECT techniques evolved over years, increasing the degree of its safety, and according to our review it appears to be relatively safe and effective during pregnancy in the majority of cases.

The impact of chronic fentanyl administration on the cerebral cortex in mice: Molecular and histological effects

PURPOSE

Fentanyl, a fully synthetic opioid, is widely used for severe pain management and has a huge abuse potential for its psychostimulant effects. Unlike other opioids, the neurotoxic effects of chronic fentanyl administration are still unclear. In particular, little is known about its effect on the cerebral cortex. The current study aims to test the chronic toxicity of fentanyl in the mice model.

METHODS

Adult male Balb/c mice were chronically treated with low (0.05 mg/kg, i.p) and high (0.1 mg/kg, i.p) doses of fentanyl for 5 consecutive weeks, and various neurotoxic parameters, including apoptosis, oxidative stress, and neuroinflammatory response were assessed in the cortex. Potential histological as well as neurochemical changes were also evaluated.

RESULTS

The results of this study show that chronic fentanyl administration induced intense levels of apoptosis, oxidative stress, and neuroinflammation in the cerebral cortex. These findings were found to be correlated with histopathological characteristics of neural degeneration and white matter injury. Moreover, fentanyl administration was found to reduce the expression of both NMDA receptor subunits and dopamine receptors and elevate the level of epidermal growth factor (EGF).

CONCLUSION

Fentanyl administration induced neurotoxic effects in the mouse cerebral cortex that could be primarily mediated by the evoked oxidative-inflammatory response. The altered expression of NMDA receptors, dopamine receptors, and EGF suggests the pernicious effects of fentanyl addiction that may end in the development of toxic psychosis.

Novel Therapeutic and Program-Based Approaches to Opioid Use Disorders

Opioid use disorder continues to drive overdose deaths in many countries, including the United States. Illicit fentanyl and its analogues have emerged as key contributors to the complications and mortality associated with opioid use disorder. Medications for opioid use disorder treatment, such as methadone and buprenorphine, are safe and substantially reduce opioid use, infectious complications, and mortality risk, but remain underutilized. Polysubstance use and emerging substances such as xylazine and designer benzodiazepines create additional treatment challenges. Recent clinical and policy innovations in treatment delivery, including telemedicine, bridge clinics, and expanded models for accessing methadone have the potential to increase access to life-saving care for people living with opioid use disorder.

IUPHAR review - Data-driven computational drug repurposing approaches for opioid use disorder

Opioid Use Disorder (OUD) is a chronic and relapsing condition characterized by the misuse of opioid drugs, causing significant morbidity and mortality in the United States. Existing medications for OUD are limited, and there is an immediate need to discover treatments with enhanced safety and efficacy. Drug repurposing aims to find new indications for existing medications, offering a time-saving and cost-efficient alternative strategy to traditional drug discovery. Computational approaches have been developed to further facilitate the drug repurposing process. In this paper, we reviewed state-of-the-art data-driven computational drug repurposing approaches for OUD and discussed their advantages and potential challenges. We also highlighted promising repurposed candidate drugs for OUD that were identified by computational drug repurposing techniques and reviewed studies supporting their potential mechanisms of action in treating OUD.

Receipt of opioid use disorder treatments prior to fatal overdoses and comparison to no treatment in Connecticut, 2016-17

OBJECTIVE

To determine the relative risk of death following exposure to treatments for OUD compared to no treatment.

METHODS

In this retrospective cohort study we compiled and merged state agency data on accidental and undetermined opioid overdose deaths in 2017 and exposures to OUD treatment in the prior six months to determine incidence rates following exposure to different treatment modalities. These rates were compared to the estimated incidence among those exposed to no treatment to determine relative risk of death for each treatment exposure.

RESULTS

Incidence rates for opioid poisoning deaths for those exposed to treatment ranged from 6.06±1.40 per 1000 persons exposed to methadone to 17.36±3.22 per 1000 persons exposed to any non-medication treatment. The estimated incidence rate for those not exposed to treatment was 9.80±0.72 per 1000 persons. With no exposure to treatment as referent, exposure to methadone or buprenorphine reduced the relative risk by 38% or 34%, respectively; the relative risk of non-medication treatments was equal to or worse than no exposure to treatment (RR = 1.27-1.77).

PRINCIPAL CONCLUSIONS

Exposure to non-MOUD treatments provided no protection against fatal opioid poisoning whereas the relative risk was reduced following exposures to MOUD treatment, even if treatment was not continued. Population level efforts to reduce opioid overdose deaths need to focus on expanding access to agonist-based MOUD treatments and are unlikely to succeed if access to non-MOUD treatments is made more available.

Cardiac and mortality outcome differences between methadone, buprenorphine and naltrexone prescriptions in patients with an opioid use disorder

IMPORTANCE

More than 109,000 Americans died of drug overdose in 2022, with 81,231 overdose deaths involving opioids. Methadone, buprenorphine and naltrexone are the most widely used medications for opioid use disorders (MOUD) and the most effective intervention for preventing overdose deaths. However, there is a concern that methadone results in long QT syndrome, which increases the risk for fatal cardiac arrythmias. Currently few studies have systematically evaluated both the short-term and long-term differences in cardiac and mortality outcomes between MOUD.

OBJECTIVES

To compare the risks of cardiac arrythmias, long QT syndrome and overall mortality between patients with opioid use disorders (OUD) who were prescribed methadone, buprenorphine or naltrexone.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cohort study based on a multicenter and nationwide database of electronic health records (EHRs) in the United States. The study population was comprised of 144,141 patients who had medical encounters for OUD in 2016-2022, were prescribed MOUD within 1 month following a medical encounter for OUD diagnosis and had no diagnosis of cardiac arrythmias or long QT syndrome before any MOUD prescription. The study population was divided into three cohorts: (1) Methadone cohort (n = 40,938)-who were only prescribed methadone. (2) Buprenorphine cohort (n = 80,055)-who were only prescribed buprenorphine. (3) Naltrexone cohort (n = 5,738)-who were only prescribed naltrexone.

EXPOSURES

methadone, buprenorphine, or naltrexone.

MAIN OUTCOMES AND MEASURES

Cardiac arrythmias, long QT syndrome, and death. Hazard ratio (HR) and 95% confidence interval (CI) of outcomes at six different follow-up time frames (1-month, 3-month, 6-month, 1-year, 3-year, and 5-year) by comparing propensity-score matched cohorts using Kaplan-Meier survival analysis.

RESULTS

Patients with OUD who were prescribed methadone had significantly higher risks of cardiac arrhythmias, long QT syndrome and death compared with propensity-score matched patients with OUD who were prescribed buprenorphine or naltrexone. For the 1-month follow-up, the overall risk for cardiac arrythmias was 1.03% in the Methadone cohort, higher than the 0.87% in the matched Buprenorphine cohort (HR: 1.20, 95% CI: 1.04-1.39); The overall risk for long QT syndrome was 0.35% in the Methadone cohort, higher than the 0.15% in the matched Buprenorphine cohort (HR: 2.40, 95% CI: 1.75-3.28); The overall mortality was 0.59% in the Methadone cohort, higher than the 0.41% in the matched Buprenorphine cohort (HR: 1.48, 95% CI: 1.21-1.81). The increased risk persisted for 5 years: cardiac arrhythmias (HR: 1.31, 95% CI: 1.23-1.38), long QT syndrome (HR: 3.14, 95% CI: 2.76-3.58), death (HR: 1.50, 95% CI: 1.41-1.59).

CONCLUSIONS AND RELEVANCE

Methadone was associated with a significantly higher risk for cardiac and mortality outcomes than buprenorphine and naltrexone. These findings are relevant to the development of guidelines for medication selection when initiating MOUD treatment and inform future medication development for OUD that minimizes risks while maximizing benefits.

Adaptation of the Tele-Harm Reduction intervention to promote initiation and retention in buprenorphine treatment among people who inject drugs: a retrospective cohort study

Background: At the start of the pandemic, relaxation of buprenorphine prescribing regulations created an opportunity to create new models of medications for opioid use disorder (MOUD) delivery and care. To expand and improve access to MOUD, we adapted and implemented the Tele-Harm Reduction (THR) intervention; a multicomponent, telehealth-based and peer-driven intervention to promote HIV viral suppression among people who inject drugs (PWID) accessing a syringe services program (SSP). This study examined buprenorphine initiation and retention among PWID with opioid use disorder who received the adapted THR intervention at the IDEA Miami SSP.Methods: A retrospective chart review of participants who received the THR intervention for MOUD was performed to examine the impact of telehealth on buprenorphine retention. Our primary outcome was three-month retention, defined as three consecutive months of buprenorphine dispensed from the pharmacy.Results: A total of 109 participants received the adapted THR intervention. Three-month retention rate on buprenorphine was 58.7%. Seeing a provider via telehealth at baseline or any follow up visit (aOR = 7.53, 95% CI: [2.36, 23.98]) and participants who had received an escalating dose of buprenorphine after baseline visit (aOR = 8.09, 95% CI: [1.83, 35.87]) had a higher adjusted odds of retention at three months. Participants who self-reported or tested positive for a stimulant (methamphetamine, amphetamine, or cocaine) at baseline had a lower adjusted odds of retention on buprenorphine at three months (aOR = 0.29, 95% CI: [0.09, 0.93]).Conclusions: Harm reduction settings can adapt dynamically to the needs of PWID in provision of critical lifesaving buprenorphine in a truly destigmatising approach. Our pilot suggests that an SSP may be an acceptable and feasible venue for delivery of THR to increase uptake of buprenorphine by PWID and promote retention in care.KEY MESSAGESThe Tele-Harm Reduction intervention can be adapted for initiating and retaining people who inject drugs with opioid use disorder on buprenorphine within a syringe services program settingUsing telehealth was associated with increased three-month buprenorphine retentionBaseline stimulant use was negatively associated with three-month buprenorphine retention.

Safety and Efficacy of Rapid Methadone Titration for Opioid Use Disorder in an Inpatient Setting: A Retrospective Cohort Study

OBJECTIVES

Inpatient guidelines for methadone titration do not exist, whereas outpatient guidelines lack flexibility and do not consider individual opioid tolerance. The evaluation of rapid, adaptable titration protocols may allow more patient-centered and effective treatment for opioid use disorder in the fentanyl era.

METHODS

This study performed a retrospective chart review of patients 18 years or older with opioid use disorder who were initiated on methadone at a single academic urban hospital using a rapid divided dose protocol between November 2019 and November 2020. The primary outcome was adverse events associated with methadone, specifically opioid toxicity or sedation requiring increased medical observation or intervention. The secondary outcome was total daily dose of methadone received on day 7 of titration.

RESULTS

Ninety-eight patients were included for a total of 168 visits. Sixty-five (66%) were male, with a median age of 38 years (interquartile range, 31-42 years). Sedation occurred in 2 patients (1%), who required either naloxone administration or transfer to an intensive care unit for monitoring. Of the 135 visits where patients received at least 7 days of methadone, the mean dose on day 1 was 41 mg (SD, 9.6 mg) and on day 7 was 65 mg (SD, 20.9 mg).

CONCLUSIONS

In this inpatient cohort, rapid methadone titration was well tolerated and resulted in patients reaching higher doses of methadone than would be possible with a standard schedule, with few adverse events. Given the known effective dose range, this approach may result in shorter time to clinical stabilization and suggests that alternative methadone titration schedules may be safe and effective in appropriately selected patients.

On the challenge of unambiguous identification of fentanyl analogs: Exploring measurement diversity using standard reference mass spectral libraries

Fentanyl analogs are a class of designer drugs that are particularly challenging to unambiguously identify due to the mass spectral and retention time similarities of unique compounds. In this paper, we use agglomerative hierarchical clustering to explore the measurement diversity of fentanyl analogs and better understand the challenge of unambiguous identifications using analytical techniques traditionally available to drug chemists. We consider four measurements in particular: gas chromatography retention indices, electron ionization mass spectra, electrospray ionization tandem mass spectra, and direct analysis in real time mass spectra. Our analysis demonstrates how simultaneously considering data from multiple measurement techniques increases the observable measurement diversity of fentanyl analogs, which can reduce identification ambiguity. This paper further supports the use of multiple analytical techniques to identify fentanyl analogs (among other substances), as is recommended by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG).

Decoding hidden darknet networks: What we learned about the illicit fentanyl trade on AlphaBay

The opioid epidemic, impacted from the proliferation of fentanyl, has added impetus to the need to detect fentanyl, sources of fentanyl, and places where fentanyl and drugs adulterated with fentanyl are available. Many darknet marketplaces (DNMs) have rules that ban fentanyl. However, it is unclear how these affect the fentanyl market. Using the AlphaBay DNM as a case study, we conducted mixed methods qualitative research. We scraped and analyzed data from the AlphaBay I2P website using, among other methods, content and social network analysis, to uncover hidden fentanyl networks. Our research highlights the next evolution of darknet marketplaces - the migration of DNMs from Tor to I2P and the methods that can be used identify fentanyl networks, irrespective of where sites are: I2P, Tor, or multihomed on I2P and Tor. Despite its ban in the Global AlphaBay Rules, our research revealed the sale of fentanyl on the AlphaBay DNM. Unlike previous studies, our findings predominantly revealed the covert sale of fentanyl on AlphaBay and predatory vendors selling illicit drugs, which unbeknownst to buyers, contained fentanyl. To a lesser extent, our findings identified the overt sale of fentanyl patches on AlphaBay. Although we examined only one DNM, the prevalence of the covert sale of fentanyl and the presence of predatory vendors underscores the importance of research that decodes the language of vendors who surreptitiously sell fentanyl or drugs adulterated with fentanyl or other illicit substances. The results of our research can inform strategies aimed at disrupting and dismantling DNM fentanyl networks.

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.

Revolutionizing Precision Medicine: Exploring Wearable Sensors for Therapeutic Drug Monitoring and Personalized Therapy

Precision medicine, particularly therapeutic drug monitoring (TDM), is essential for optimizing drug dosage and minimizing toxicity. However, current TDM methods have limitations, including the need for skilled operators, patient discomfort, and the inability to monitor dynamic drug level changes. In recent years, wearable sensors have emerged as a promising solution for drug monitoring. These sensors offer real-time and continuous measurement of drug concentrations in biofluids, enabling personalized medicine and reducing the risk of toxicity. This review provides an overview of drugs detectable by wearable sensors and explores biosensing technologies that can enable drug monitoring in the future. It presents a comparative analysis of multiple biosensing technologies and evaluates their strengths and limitations for integration into wearable detection systems. The promising capabilities of wearable sensors for real-time and continuous drug monitoring offer revolutionary advancements in diagnostic tools, supporting personalized medicine and optimal therapeutic effects. Wearable sensors are poised to become essential components of healthcare systems, catering to the diverse needs of patients and reducing healthcare costs.

The Cost-Effectiveness of Financial Incentives to Achieve Heroin Abstinence in Individuals With Heroin Use Disorder Starting New Treatment Episodes: A Cluster Randomized Trial-Based Economic Evaluation

OBJECTIVES

Cost-effectiveness analysis of two 12-week contingency management (CM) schedules targeting heroin abstinence or attendance at weekly keyworker appointments for opioid agonist treatment compared with treatment as usual (TAU).

METHODS

A cost-effectiveness analysis was conducted alongside a cluster randomized trial of 552 patients from 34 clusters (drug treatment clinics) randomly allocated 1:1:1 to opioid agonist treatment plus weekly keyworker appointments with (1) CM targeted at heroin abstinence (CM abstinence), (2) CM targeted at on-time attendance at weekly appointments (CM attendance), or (3) no CM (TAU). The primary cost-effectiveness analysis at 24 weeks after randomization took a societal cost perspective with effects measured in heroin-negative urine samples.

RESULTS

At 24 weeks, mean differences in weekly heroin-negative urine results compared with TAU were 0.252 (95% confidence interval [CI] -0.397 to 0.901) for CM abstinence and 0.089 (95% CI -0.223 to 0.402) for CM attendance. Mean differences in costs were £2562 (95% CI £32-£5092) for CM abstinence and £317 (95% CI -£882 to £1518) for CM attendance. Incremental cost-effectiveness ratios were £10 167 per additional heroin-free urine for CM abstinence and £3562 for CM attendance with low probabilities of cost-effectiveness of 3.5% and 36%, respectively. Results were sensitive to timing of follow-up for CM attendance, which dominated TAU (better outcomes, lower costs) at 12 weeks, with an 88.4% probability of being cost-effective. Probability of cost-effectiveness remained low for CM abstinence (8.6%).

CONCLUSIONS

Financial incentives targeted toward heroin abstinence and treatment attendance were not cost-effective over the 24-week follow-up. Nevertheless, CM attendance was cost-effective over the treatment period (12 weeks), when participants were receiving keyworker appointments and incentives.

Differential effect of cannabis use on opioid agonist treatment outcomes: Exploratory analyses from the OPTIMA study

INTRODUCTION

Conflictual evidence exists regarding the effects of cannabis use on the outcomes of opioid agonist therapy (OAT). In this exploratory analysis, we examined the effect of recent cannabis use on opioid use, craving, and withdrawal symptoms, in individuals participating in a trial comparing flexible buprenorphine/naloxone (BUP/NX) take-home dosing model to witnessed ingestion of methadone.

METHODS

We analyzed data from a multi-centric, pragmatic, 24-week, open label, randomized controlled trial in individuals with prescription-type opioid use disorder (n = 272), randomly assigned to BUP/NX (n = 138) or methadone (n = 134). The study measured last week cannabis and opioid use via timeline-follow back, recorded at baseline and every two weeks during the study. Craving symptoms were measured using the Brief Substance Craving Scale at baseline, and weeks 2, 6, 10, 14, 18 and 22. The study measured opioid withdrawal symptoms via Clinical Opiate Withdrawal Scale at treatment initiation and weeks 2, 4, and 6.

RESULTS

The mean maximum dose taken during the study was 17.3 mg/day (range = 0.5-32 mg/day) for BUP/NX group and 67.7 mg/day (range = 10-170 mg/day) in the methadone group. Repeated measures generalized linear mixed models demonstrated that cannabis use in the last week (mean of 2.3 days) was not significantly associated with last week opioid use (aβ ± standard error (SE) = -0.06 ± 0.04; p = 0.15), craving (aβ ± SE = -0.05 ± 0.08, p = 0.49), or withdrawal symptoms (aβ ± SE = 0.09 ± 0.1, p = 0.36). Bayes factor (BF) for each of the tested models supported the null hypothesis (BF < 0.3).

CONCLUSIONS

The current study did not demonstrate a statistically significant effect of cannabis use on outcomes of interest in the context of a pragmatic randomized-controlled trial. These findings replicated previous results reporting no effect of cannabis use on opioid-related outcomes.

A Novel Inpatient Buprenorphine Induction Program for Adolescents With Opioid Use Disorder

BACKGROUND

Morbidity and mortality from nonprescribed opioid use and opioid use disorder (OUD) in adolescents have risen dramatically. Medication for opioid use disorder (MOUD) with buprenorphine reduces nonprescribed opioid use and prevents overdoses, though <5% of adolescents with OUD have timely access, partly because of barriers associated with buprenorphine induction. Induction in an inpatient pediatric setting has the potential to address such barriers and improve adolescent MOUD access.

METHODS

We developed and implemented a protocol for inpatient buprenorphine induction and linkage to MOUD care within a safety-net health system. After 1 year, we conducted descriptive analysis of participant characteristics, rates of induction completion and treatment linkage, and adverse events. We analyzed field notes from multidisciplinary huddles to identify implementation facilitators and barriers.

RESULTS

During May 2021 to July 2022, we completed 46 admissions for 36 patients aged 12 to 21 years. All used fentanyl and no other opioids. Forty of 46 (87%) admissions resulted in completed induction, and 3 additional patients never developed withdrawal symptoms and were discharged with maintenance buprenorphine. Linkage to ongoing treatment occurred within 2 weeks for 31 of 43 (72%) admissions for which buprenorphine was started. We identified facilitators and barriers to program implementation and maintenance.

CONCLUSION

These results provide promising preliminary evidence of the feasibility of inpatient buprenorphine induction for adolescents with OUD. Given the public health urgency and severe shortage of adolescent access to MOUD, these results prompt consideration of broader clinical implementation and research to facilitate rapid expansion of access to evidence-based OUD care.

Vitamin D Deficiency and Risk Factors Related to Acute Psychiatric Relapses in Patients with Severe Mental Disorders: A Preliminary Study

Previous studies have indicated that vitamin (Vit) D deficiency is frequent in psychiatric patients, regardless of diagnostic category. We aimed to assess whether acute psychiatric relapses in inpatients was associated with Vit D deficiency compared to stabilized outpatients. The cohort (152 total patients, 75 males and 77 females) had a mean age of 47.3 ± 14.4 years at admission and was grouped according to psychiatric diagnosis. Psychopathological symptom severity was assessed by the Brief Psychiatric Rating Scale (BPRS), a multidimensional symptom inventory. Total calcium serum levels were measured using standard laboratory methods, while plasma levels of 25-OH-Vit D and parathyroid hormone (PTH) were measured by automated chemiluminescence immunoassays. The psychiatric inpatient subgroup showed a significant difference in serum levels of 25-OH-Vit D and PTH (p < 0.001). Correlation analysis between serum levels of 25-OH-Vit D and BPRS total and subitem scores indicated a significantly negative relationship. In addition, linear regression analysis evidenced that the inpatient condition might predict low PTH and 25-OH-Vit D serum levels. Hospitalized psychiatric patients are at increased risk for Vit D deficiency regardless of their diagnostic categories. The mechanism underlying the association between acute psychiatric relapses and Vit D deficiency remains unclear. Therefore, screening for Vit D deficiency should pertain to the health assessment of patients with major psychiatric disorders.

"They say it's fentanyl, but they honestly look like Perc 30s": Initiation and use of counterfeit fentanyl pills

BACKGROUND

Worsening of the overdose crisis in the USA has been linked to the continuing proliferation of non-pharmaceutical fentanyl (NPF). The recent wave of NPF spread in the USA has been fueled by an increased presence of counterfeit pills that contain NPF. This qualitative study aims to characterize the motivation and practices of counterfeit NPF pill initiation and use among individuals using illicit opioids in Arizona.

METHODS

Between October 2020 and May 2021, semi-structured interviews were conducted with 22 individuals meeting the following eligibility criteria: (1) 18 years or older; (2) residence in Arizona; and (3) use of illicit opioids in the past 30 days and/or opioid use disorder treatment in the past 12 months. Participants were recruited through referrals by a harm reduction organization, craigslist ads, and referrals by other participants. Interviews were conducted virtually via Zoom. Qualitative interviews were transcribed and analyzed thematically using NVivo.

RESULTS

Out of 22 participants, 64% were male, and 45% were ethnic minorities. Age ranged between 25 and 51 years old. Participants noted significant recent increases in the availability of counterfeit NPF pills ("blues," "dirty oxys") that were most commonly used by smoking. The majority indicated first trying NPF pills in the past year, and the first use often occurred in situations of reduced access to heroin or pharmaceutical opioids. Participant decisions to switch over to more frequent NPF pill use or to maintain some levels of heroin use were shaped by local drug availability trends and personal experiences with NPF effects. They were also influenced by conflicting views of social acceptability of pharmaceutical-like drugs, perceived harms of NPF in terms of overdose risks and increased difficulty of quitting, and perceived benefits of switching to the non-injection route of opioid administration (e.g., from injecting heroin to smoking NPF pills).

CONCLUSION

Our findings highlight the need for the implementation of novel policy, treatment, and harm reduction approaches to address the growing unpredictability of drug supply and NPF pill-specific risks, attitudes, and behaviors.

Unique Pharmacology, Brain Dysfunction, and Therapeutic Advancements for Fentanyl Misuse and Abuse

Fentanyl is a fully synthetic opioid with analgesic and anesthetic properties. It has become a primary driver of the deadliest opioid crisis in the United States and elsewhere, consequently imposing devastating social, economic, and health burdens worldwide. However, the neural mechanisms that underlie the behavioral effects of fentanyl and its analogs are largely unknown, and approaches to prevent fentanyl abuse and fentanyl-related overdose deaths are scarce. This review presents the abuse potential and unique pharmacology of fentanyl and elucidates its potential mechanisms of action, including neural circuit dysfunction and neuroinflammation. We discuss recent progress in the development of pharmacological interventions, anti-fentanyl vaccines, anti-fentanyl/heroin conjugate vaccines, and monoclonal antibodies to attenuate fentanyl-seeking and prevent fentanyl-induced respiratory depression. However, translational studies and clinical trials are still lacking. Considering the present opioid crisis, the development of effective pharmacological and immunological strategies to prevent fentanyl abuse and overdose are urgently needed.

Naloxone's dose-dependent displacement of [11C]carfentanil and duration of receptor occupancy in the rat brain

The continuous rise in opioid overdoses in the United States is predominantly driven by very potent synthetic opioids, mostly fentanyl and its derivatives (fentanyls). Although naloxone (NLX) has been shown to effectively reverse overdoses by conventional opioids, there may be a need for higher or repeated doses of NLX to revert overdoses from highly potent fentanyls. Here, we used positron emission tomography (PET) to assess NLX's dose-dependence on both its rate of displacement of [¹¹C]carfentanil ([¹¹C]CFN) binding and its duration of mu opioid receptor (MOR) occupancy in the male rat brain. We showed that clinically relevant doses of intravenously (IV) administered NLX (0.035 mg/kg, Human Equivalent Dose (HED) 0.4 mg; 0.17 mg/kg, HED 2 mg) rapidly displaced the specific binding of [¹¹C]CFN in the thalamus in a dose-dependent manner. Brain MOR occupancy by IV NLX was greater than 90% at 5 min after NLX administration for both doses, but at 27.3 min after 0.035 mg/kg dose and at 85 min after 0.17 mg/kg NLX, only 50% occupancy remained. This indicates that the duration of NLX occupancy at MORs is short-lived. Overall, these results show that clinically relevant doses of IV NLX can promptly displace fentanyls at brain MORs, but repeated or higher NLX doses may be required to prevent re-narcotization following overdoses with long-acting fentanyls.

Modelling buprenorphine reduction of fentanyl-induced respiratory depression

BACKGROUND

Potent synthetic opioids, such as fentanyl, are increasingly abused, resulting in unprecedented numbers of fatalities from respiratory depression. Treatment with the high-affinity mu-opioid receptor partial agonist buprenorphine may prevent fatalities by reducing binding of potent opioids to the opioid receptor, limiting respiratory depression.

METHODS

To characterize buprenorphine-fentanyl interaction at the level of the mu-opioid receptor in 2 populations (opioid-naive individuals and individuals who chronically use high-dose opioids), the effects of escalating i.v. fentanyl doses with range 0.075–0.35 mg/70 kg (opioid naive) and 0.25–0.70 mg/70 kg (chronic opioid use) on iso-hypercapnic ventilation at 2–3 background doses of buprenorphine (target plasma concentrations range: 0.2–5 ng/mL) were quantified using receptor association/dissociation models combined with biophase distribution models.

RESULTS

Buprenorphine produced mild respiratory depression, while high doses of fentanyl caused pronounced respiratory depression and apnea in both populations. When combined with fentanyl, buprenorphine produced a receptor binding–dependent reduction of fentanyl-induced respiratory depression in both populations. In individuals with chronic opioid use, at buprenorphine plasma concentrations of 2 ng/mL or higher, a protective effect against high-dose fentanyl was observed.

CONCLUSION

Overall, the results indicate that when buprenorphine mu-opioid receptor occupancy is sufficiently high, fentanyl is unable to activate the mu-opioid receptor and consequently will not cause further respiratory depression in addition to the mild respiratory effects of buprenorphine.

TRIAL REGISTRATION

Trialregister.nl, no. NL7028 (https://www.trialregister.nl/trial/7028)

FUNDING

Indivior Inc., North Chesterfield, Virginia, USA.

Novel bivalent ligands carrying potential antinociceptive effects by targeting putative mu opioid receptor and chemokine receptor CXCR4 heterodimers

The functional interactions between opioid and chemokine receptors have been implicated in the pathological process of chronic pain. Mounting studies have indicated the possibility that a MOR-CXCR4 heterodimer may be involved in nociception and related pharmacologic effects. Herein we have synthesized a series of bivalent ligands containing both MOR agonist and CXCR4 antagonist pharmacophores with an aim to investigate the functional interactions between these two receptors. In vitro studies demonstrated reasonable recognition of designed ligands at both respective receptors. Further antinociceptive testing in mice revealed compound 1a to be the most promising member of this series. Additional molecular modeling studies corroborated the findings observed. Taken together, we identified the first bivalent ligand 1a showing promising antinociceptive effect by targeting putative MOR-CXCR4 heterodimers, which may serve as a novel chemical probe to further develop more potent bivalent ligands with potential application in analgesic therapies for chronic pain management.

Protracted abstinence in males with an opioid use disorder: partial recovery of nucleus accumbens function

Opioid use disorder (OUD) affects more than 27 million people globally accounting for more than 300,000 deaths annually. Protracted abstinence among individuals with OUD is rare due to a high relapse rate among those not receiving medications for OUD. Extensive preclinical studies form the basis of the allostasis theory, which proposes long-lasting functional brain abnormalities that persist after opioid withdrawal and contribute to relapse. Few studies have tested the allostasis theory in humans using neuroimaging. Here, we used fMRI and an instrumental learning task to test allostasis theory predictions (ATP) of functional abnormalities in both positive valence (PVS) and negative valence (NVS) accumbens systems in OUD patients with protracted abstinence (n = 15), comparing them with OUD patients receiving methadone treatment (MT) (n = 33), and with healthy controls (n = 23). As hypothesized, protracted abstinence OUD patients showed incomplete recovery of nucleus accumbens function, as evidenced by the blunted response to aversive events (NVS) during negative reinforcement, as observed in MT patients. In contrast, their accumbens response to rewarding events (PVS) during positive reinforcement was similar to that of controls and different from that in MT patients whose response was blunted. Protracted abstinence OUD patients also showed improvements in depression symptoms compared to MT patients. Residual depressive symptoms and pre-MT intravenous drug measures were associated with worse accumbens function in protracted abstinence. These results support the ATP of long-lasting dysfunction of NVS after withdrawal and show preliminary evidence of recovery of PVS function with protracted withdrawal. Therapeutic strategies that target NVS may facilitate recovery.

Substance abuse and neurotransmission

The number of people who suffer from a substance abuse disorder has continued to rise over the last decade; particularly, the number of drug-related overdose deaths has sharply increased during the COVID-19 pandemic. Converging lines of clinical observations, supported by imaging and neuropsychological performance testing, have demonstrated that substance abuse-induced dysregulation of neurotransmissions in the brain is critical for development and expression of the addictive properties of abused substances. Recent scientific advances have allowed for better understanding of the neurobiological processes that mediates drugs of abuse and addiction. This chapter presents the past classic concepts and the recent advances in our knowledge about how cocaine, amphetamines, opioids, alcohol, and nicotine alter multiple neurotransmitter systems, which contribute to the behaviors associated with each drug. Additionally, we discuss the interactive effects of HIV-1 or COVID-19 and substance abuse on neurotransmission and neurobiological pathways. Finally, we introduce therapeutic strategies for development of pharmacotherapies for substance abuse disorders.

Treatment of opioid overdose: current approaches and recent advances

BACKGROUND

The USA has recently entered the third decade of the opioid epidemic. Opioid overdose deaths reached a new record of over 74,000 in a 12-month period ending April 2021. Naloxone is the primary opioid overdose reversal agent, but concern has been raised that naloxone is not efficacious against the pervasive illicit high potency opioids (i.e., fentanyl and fentanyl analogs).

METHODS

This narrative review provides a brief overview of naloxone, including its history and pharmacology, and the evidence regarding naloxone efficacy against fentanyl and fentanyl analogs. We also highlight current advances in overdose treatments and technologies that have been tested in humans.

RESULTS AND CONCLUSIONS

The argument that naloxone is not efficacious against fentanyl and fentanyl analogs rests on case studies, retrospective analyses of community outbreaks, pharmacokinetics, and pharmacodynamics. No well-controlled studies have been conducted to test this argument, and the current literature provides limited evidence to suggest that naloxone is ineffective against fentanyl or fentanyl analog overdose. Rather a central concern for treating fentanyl/fentanyl analog overdose is the rapidity of overdose onset and the narrow window for treatment. It is also difficult to determine if other non-opioid substances are contributing to a drug overdose, for which naloxone is not an effective treatment. Alternative pharmacological approaches that are currently being studied in humans include other opioid receptor antagonists (e.g., nalmefene), respiratory stimulants, and buprenorphine. None of these approaches target polysubstance overdose and only one novel approach (a wearable naloxone delivery device) would address the narrow treatment window.

Visualizing a Calculus of Recovery: Calibrating Relations in an Opioid Epicenter

This article uses participatory photography to explore the relationships animating efforts towards recovery from opioid use disorder (OUD) in the Dayton, Ohio area, an epicenter of illicit opioid use and overdose death. A photo-elicitation project was conducted with thirteen people who met the DSM-5 criteria for OUD. Photographs were used as prompts during qualitative interviews, which were thematically analyzed. Analysis of both visual and textual data demonstrated the ways in which recovery became an unfolding process of calculation as participants made strategic choices to navigate relations and encounters with things, people, and places. Relationships across each of these domains could, under some circumstances, serve as supports or motivators in the recovery process, but, in alternate settings, be experienced as "triggers" prompting a resumption of problematic drug use or, at the very least, a reckoning with the feelings and emotions associated with painful or problematic aspects of personal histories and drug use experiences. Findings highlight the importance of understanding recovery as a calibration of the ambiguous relations animating experiences of everyday life. We argue for continued emphasis on recovery as an active performance and ongoing practice of calculation-of risks and benefits, of supports and triggers, of gratification and heartbreak-rather than a goal or static state.

Synergistic Effect of Ketamine and Buprenorphine Observed in the Treatment of Buprenorphine Precipitated Opioid Withdrawal in a Patient With Fentanyl Use

BACKGROUND

Optimal treatment of buprenorphine precipitated opioid withdrawal (BPOW) is unclear. Full agonist treatment of BPOW is limited by buprenorphine's high-affinity blockade at mu-opioid receptors (μORs). Buprenorphine's partial agonism (low intrinsic efficacy) at μORs can limit the effectiveness of even massive doses once BPOW has begun. Adjunct medications, such as clonidine, are rarely effective in severe BPOW. Ketamine is an N-methyl-D-aspartate receptor antagonist with a potentially ideal pharmacologic profile for treatment of BPOW. Ketamine reduces opioid withdrawal symptoms independently of direct μOR binding, synergistically potentiates the effectiveness of buprenorphine μOR signaling, reverses (resensitizes) fentanyl induced μOR receptor desensitization, and inhibits descending pathways of hyperalgesia and central sensitization. Ketamine's rapid antidepressant effects potentially address depressive symptoms and subjective distress that often accompanies BPOW. Ketamine is inexpensive, safe, and available in emergency departments. To date, neither ketamine as treatment for BPOW nor to support uncomplicated buprenorphine induction has been described.

CASE DESCRIPTION

We report a case of an illicit fentanyl-using OUD patient who experienced severe BPOW during an outpatient low-dose cross taper buprenorphine induction (ie, "microdose"). The BPOW was successfully treated in the emergency department with a combination of ketamine (0.6 mg/kg intravenous over 1 hour) combined with high-dose buprenorphine (16 mg sublingual single dose); 3 days later he was administered a month-long dose of extended-release subcutaneous buprenorphine which was repeated monthly (300 mg). At 90 days the patient remained in treatment and reported continuous abstinence from fentanyl use.

CONCLUSIONS

This single case observation raises important questions about the potential therapeutic role of ketamine as a treatment for BPOW. BPOW is an important clinical problem for which there is currently only limited guidance and no universally accepted approach. Prospective study comparing the effectiveness of differing pharmacologic approaches to treat BPOW is urgently needed.

Design, synthesis, and preliminary evaluation of a potential synthetic opioid rescue agent

Background

One of the most prominent opioid analgesics in the United States is the high potency agonist fentanyl. It is used in the treatment of acute and chronic pain and as an anesthetic adjuvant. When used inappropriately, however, ingestion of just a few milligrams of fentanyl or other synthetic opioid can cause opioid-induced respiratory depression (OIRD), often leading to death. Currently, the treatment of choice for OIRD is the opioid receptor antagonist naloxone. Recent reports, however, suggest that higher doses or repeated dosing of naloxone (due to recurrence of respiratory depression) may be required to reverse fully fentanyl-induced respiratory depression, rendering this treatment inadequate. To combat this synthetic opioid overdose crisis, this research aims at identifying a novel opioid reversal agent with enhanced efficacy towards fentanyl and other synthetic opioids.

Methods

A series of naltrexone analogues were characterized for their ability to antagonize the effects of fentanyl in vitro utilizing a modified forskolin-induced cAMP accumulation assay. Lead analogue 29 was chosen to undergo further PK studies, followed by in vivo pharmacological analysis to determine its ability to antagonize opioid-induced antinociception in the hot plate assay.

Results

A series of potent MOR antagonists were identified, including the highly potent analogue 29 (IC₅₀ = 2.06 nM). Follow-up PK studies revealed 29 to possess near 100% bioavailability following IP administration. Brain concentrations of 29 surpassed plasma concentrations, with an apparent terminal half-life of ~ 80 min in mice. In the hot plate assay, 29 dose-dependently (0.01–0.1 mg/kg; IP) and fully antagonized the antinociception induced by oxycodone (5.6 mg/kg; IP). Furthermore, the dose of 29 that is fully effective in preventing oxycodone-induced antinociception (0.1 mg/kg) was ineffective against locomotor deficits caused by the KOR agonist U50,488.

Conclusions

Methods have been developed that have utility to identify enhanced rescue agents for the treatment of OIRD. Analogue 29, possessing potent MOR antagonist activity in vitro and in vivo, provides a promising lead in our search for an enhanced synthetic opioid rescue agent.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00758-y.