Medications for opioid use disorders: clinical and pharmacological considerations

Efficacy of transdermal buprenorphine patch for managing withdrawal symptoms in patients with cancer physically dependent on prescription opioids

BACKGROUND

The physical dependence on prescription opioids among cancer survivors remains an under-investigated area, with a scarcity of well-designed prospective studies.

METHODS

This single-arm, phase-2 clinical trial in Korea assessed the efficacy and safety of a transdermal buprenorphine patch (TBP) in managing physical dependence on prescription opioids in cancer survivors, as confirmed through the DSM-5 criteria or psychiatric consultation for opioid withdrawal. This study involved a 4-phase treatment protocol of screening, induction/stabilization, discontinuation, and monitoring. The primary outcome was the rate of successful opioid discontinuation, as measured by a negative urine-drug screening at 8 weeks. Key secondary outcomes included the resumption of prescribed opioids, changes in both the Clinical Opioid Withdrawal Scale (COWS) and morphine equivalent daily dose (MEDD), and assessments related to the psychological and physiological aspects of dependence and safety.

RESULTS

Thirty-one participants were enrolled. In the intention-to-treat population, the success rate of opioid discontinuation was 58%, with only 2 participants experiencing a resumption of prescribed opioids. Significant reductions were observed in MEDD, which decreased from 98 to 26 mg/day (P < .001), and COWS scores, which decreased from 5.5 to 2.8 (P < .001). Desire to use opioids reduced from 7.0 to 3.0 on a 10-point numeric rating scale (P < .001). Toxicities related to TBP were mild and manageable, without severe precipitated withdrawal symptoms.

CONCLUSION

TBP may be considered as an alternative therapeutic option in cancer survivors physically dependent on prescription opioids, especially where sublingual formulations are unavailable.

Rotation from methadone to buprenorphine using a micro-dosing regime in patients with opioid use disorder and serious mental illness: A case series

INTRODUCTION

Inducting buprenorphine from methadone has traditionally involved initial opioid withdrawal, with risk of mental state deterioration in patients with serious mental illness (SMI). Micro-dosing of buprenorphine, with small incremental doses, is a novel off-label approach to transitioning from methadone and does not require a period of methadone abstinence. Given the limited literature about buprenorphine microdosing, we aimed to evaluate the feasibility and safety of inducting buprenorphine in a series of patients on methadone with SMI.

METHODS

For this retrospective case series, we reviewed the records of 16 patients with SMI at a Melbourne addiction treatment centre, from January 2021 to July 2022, who transitioned via micro-dosing, from high-dose methadone (>30 mg) to buprenorphine and depot-buprenorphine. Psychiatric diagnoses, mental state, other substance withdrawal, transfer success, transition time, opioid withdrawal symptoms and overall patient experience were collected via objective and subjective reporting.

RESULTS

Methadone to buprenorphine transfer was completed by 88% of patients. Mental health measures remained stable with the exception of mildly increased anxiety. Median transfer time was 6.5 days for inpatients, 9 days for mixed setting and 10 days for outpatients. Most patients (93%) rated their experience 'manageable' reporting mild withdrawal symptoms. One patient met study criteria for precipitated withdrawal.

DISCUSSION AND CONCLUSIONS

This retrospective case series provides evidence that the use of a micro-dosing buprenorphine induction for methadone to buprenorphine transitions, including to depot-buprenorphine, has negligible risk, is tolerated by patients with SMI and is unlikely to precipitate an exacerbation of their mental illness.

Model of negative affect induced by withdrawal from acute and chronic morphine administration in male mice

Opioid use disorder (OUD) is a chronic relapsing disorder that is a major burden for the lives of affected individuals, and society as a whole. Opioid withdrawal is characterized by strong physical symptoms, along with signs of negative affect. Negative affect due to opioid withdrawal is a major obstacle to recovery and relapse prevention. The mechanisms behind negative affect due to either spontaneous or antagonist-precipitated opioid withdrawal are not well known, and more animal models need be developed. Here, we present behavioral models of negative affect upon naloxone-precipitated morphine withdrawal in adult male mice. Social, anxiety, and despair-like deficits were investigated following naloxone administration in mice receiving morphine under three dosing regimens; acute, chronic constant dose and chronic escalating doses. Social behaviour in the three-chamber social preference test was decreased following withdrawal from chronic and escalating but not acute morphine. Anxiety-like behaviour in the open field was increased for all three treatments. Despair-like behaviour was increased following withdrawal from chronic and escalating but not acute morphine. Altogether, these animal models will contribute to study behavioural and neuronal circuitries involved in the several negative affective signs characterizing OUD.

Racial and ethnic disparities in medication for opioid use disorder access, use, and treatment outcomes in Medicare

INTRODUCTION

Overdose deaths are increasing disproportionately for minoritized populations in the United States. Disparities in substance use disorder treatment access and use have been a key contributor to this phenomenon. However, little is known about the magnitude of these disparities and the role of social determinants of health (SDOH) and provider characteristics in driving them. Our study measures the association between race and ethnicity and visits with Medication for Opioid Use Disorder (MOUD) providers, MOUD treatment conditional on a provider visit, and opioid overdose following MOUD treatment in Medicare. We also evaluate the role of social determinants of health and provider characteristics in modifying disparities.

METHODS

Using a population of 230,198 US Medicare fee-for-service beneficiaries diagnosed with opioid use disorder (OUD), we estimate logistic regression models to quantify the association between belonging to a racial or ethnic group and the probability of visiting a buprenorphine or naltrexone provider, receiving a prescription or medication administration during or after a visit, and experiencing an opioid overdose after treatment with MOUD. Data included Medicare claims data and the Agency for Health Research and Quality Social Determinants of Health Database files between 2013 and 2017.

RESULTS

Compared to Non-Hispanic White Medicare beneficiaries, Asian/Pacific Islander, American Indian/Alaska Native, Black, Hispanic, and Other/Unknown Race beneficiaries were between 3.0 and 9.3 percentage points less likely to have a visit with a buprenorphine or naltrexone provider. Conditional on having a buprenorphine or naltrexone provider visit, Asian/Pacific Islander, American Indian/Alaska Native, Black, Hispanic, and Other/Unknown Race were between 2.6 and 8.1 percentage points less likely to receive buprenorphine or naltrexone than white beneficiaries. Controlling for provider characteristics and SDOH increased disparities in visits and MOUD treatment for all groups besides American Indians/Alaska Natives. Conditional on treatment, only Black Medicare beneficiaries were at greater associated risk of overdose than non-Hispanic white beneficiaries, although differences became statistically insignificant after controlling for SDOH and including provider fixed effects.

CONCLUSION

Ongoing equity programming and measurement efforts by CMS should include explicit consideration for disparities in access and use of MOUD. This may help ensure greater MOUD utilization by minoritized Medicare beneficiaries and reduce rising disparities in overdose deaths.

Targeting mitochondrial dynamics of morphine-responsive dopaminergic neurons ameliorates opiate withdrawal

Converging studies demonstrate the dysfunction of the dopaminergic neurons following chronic opioid administration. However, the therapeutic strategies targeting opioid-responsive dopaminergic ensembles that contribute to the development of opioid withdrawal remain to be elucidated. Here, we used the neuronal activity-dependent Tet-Off system to label dopaminergic ensembles in response to initial morphine exposure (Mor-Ens) in the ventral tegmental area (VTA). Fiber optic photometry recording and transcriptome analysis revealed downregulated spontaneous activity and dysregulated mitochondrial respiratory, ultrastructure, and oxidoreductase signal pathways after chronic morphine administration in these dopaminergic ensembles. Mitochondrial fragmentation and the decreased mitochondrial fusion gene mitofusin 1 (Mfn1) were found in these ensembles after prolonged opioid withdrawal. Restoration of Mfn1 in the dopaminergic Mor-Ens attenuated excessive oxidative stress and the development of opioid withdrawal. Administration of Mdivi-1, a mitochondrial fission inhibitor, ameliorated the mitochondrial fragmentation and maladaptation of the neuronal plasticity in these Mor-Ens, accompanied by attenuated development of opioid withdrawal after chronic morphine administration, without affecting the analgesic effect of morphine. These findings highlighted the plastic architecture of mitochondria as a potential therapeutic target for opioid analgesic-induced substance use disorders.

Vaccines to Treat Substance Use Disorders: Current Status and Future Directions

Addiction, particularly in relation to psychostimulants and opioids, persists as a global health crisis with profound social and economic ramifications. Traditional interventions, including medications and behavioral therapies, often encounter limited success due to the chronic and relapsing nature of addictive disorders. Consequently, there is significant interest in the development of innovative therapeutics to counteract the effects of abused substances. In recent years, vaccines have emerged as a novel and promising strategy to tackle addiction. Anti-drug vaccines are designed to stimulate the immune system to produce antibodies that bind to addictive compounds, such as nicotine, cocaine, morphine, methamphetamine, and heroin. These antibodies effectively neutralize the target molecules, preventing them from reaching the brain and eliciting their rewarding effects. By obstructing the rewarding sensations associated with substance use, vaccines aim to reduce cravings and the motivation to engage in drug use. Although anti-drug vaccines hold significant potential, challenges remain in their development and implementation. The reversibility of vaccination and the potential for combining vaccines with other addiction treatments offer promise for improving addiction outcomes. This review provides an overview of anti-drug vaccines, their mechanisms of action, and their potential impact on treatment for substance use disorders. Furthermore, this review summarizes recent advancements in vaccine development for each specific drug, offering insights for the development of more effective and personalized treatments capable of addressing the distinct challenges posed by various abused substances.

At a Crossroads: Opioid Use Disorder, the X-Waiver, and the Road Ahead

Background: Buprenorphine/naloxone (Suboxone) is widely considered the first-line treatment for opioid use disorder (OUD), which causes significant morbidity and mortality in the United States, but prior to 2023, practitioners interested in prescribing buprenorphine/naloxone for OUD needed a special Drug Enforcement Administration certification (the X-Waiver) that imposed a patient cap and other limitations. The Consolidated Appropriations Act of 2023 considerably decreased the restrictions on prescribing practitioners. Buprenorphine/naloxone can now be prescribed like any other prescription opioid, excluding methadone. The historic context for the opioid crisis, OUD, the X-Waiver, and additional initiatives that may be needed beyond legislative change to effectively address OUD are the subjects of this review. Methods: To develop this review of the opioid crisis, OUD, and OUD treatment, we conducted a literature search of the PubMed database and constructed a timeline of the opioid crisis and changes in OUD treatment, specifically the X-Waiver, to characterize the historic context of OUD and the X-Waiver against the background of the opioid crisis. Results: The opioid crisis has had pervasive public health and economic impacts in the United States. Major changes to the treatment of OUD have occurred as a result of the Drug Addiction Treatment Act of 2000 that imposed the X-Waiver and the Consolidated Appropriations Act of 2023 that repealed the X-Waiver. Conclusion: The repeal of the X-Waiver is predicted to increase the accessibility of buprenorphine/naloxone in the United States. However, additional work beyond legislative change, including institutional support and reduction of stigma and disparities, is needed to substantially improve outcomes for OUD patients.

Population Pharmacokinetic Analysis Supports Initiation Treatment and Bridging from Sublingual Buprenorphine to Subcutaneous Administration of a Buprenorphine Depot (CAM2038) in the Treatment of Opioid Use Disorder

BACKGROUND AND OBJECTIVE

In treating opioid use disorder (OUD), subcutaneous (SC) extended-release buprenorphine (BPN) depots, e.g., CAM2038, have been shown to provide smaller and less frequent fluctuations in BPN plasma concentrations and pharmacodynamic responses, improve outcomes, reduce treatment burden, and lower risks of misuse and diversion compared to daily sublingual (SL) BPN. This analysis characterized the pharmacokinetics (PK) of BPN following intravenous and SL administration, and administration of SC CAM2038 weekly and monthly.

METHODS

Pharmacokinetic data from two Phase 1 and two Phase 2 trials in healthy participants and participants with OUD, respectively, were used to develop a population PK model using non-linear mixed effects modelling. The analysis included data from 252 participants and 10,658 BPN observations.

RESULTS

The disposition of BPN was best described by a three-compartment model with first-order elimination, and absorption of SL BPN and SC CAM2038 weekly and monthly by dual parallel absorption pathways. Model diagnostics indicated good predictive performance of BPN concentrations. Buprenorphine plasma concentration-time profiles were simulated for treatment initiation, switching from SL BPN to CAM2038 weekly and monthly, and tapering after interrupting treatment with CAM2038. Simulations predicted CAM2038 weekly and monthly doses that provided BPN plasma maximum concentration (Cmax) and trough concentration (Ctrough) values at steady state within those observed following SL BPN administration.

CONCLUSIONS

This population PK model supports the use of CAM2038 doses as individualized treatment for OUD across different treatment stages, including initiation, switching from SL BPN according to established dose conversion schedules, and tapering.

TRIAL REGISTRATIONS

ISRCTN41550730 (05/19/2014), ISRCTN24987553 (07/29/2014), NCT02611752 (11/23/2015), NCT02710526 (03/16/2016).

Cannabidiol Analogue for the Treatment of Morphine-Induced Addiction by Targeting PKM2

Opioid addiction is a chronically relapsing disorder that causes critical public health problems. Currently, there is a lack of effective drug treatment. Herein, one cannabidiol derivative, CIAC001, was discovered as an effective agent for treating morphine-induced addiction. In vitro, CIAC001 exhibited significantly improved anti-neuroinflammatory activity with lower toxicity. In vivo, CIAC001 ameliorated the morphine-induced withdrawal reaction, behavioral sensitization, and conditional position preference by inhibiting morphine-induced microglia activation and neuroinflammation. Target fishing for CIAC001 by activity-based protein profiling led to the identification of pyruvate kinase M2 (PKM2) as the target protein. CIAC001 bound to the protein-protein interface of the PKM2 dimer and promoted the tetramerization of PKM2. Moreover, CIAC001 exhibited an anti-neuroinflammatory effect by reversing the decrease of the PKM2 tetramer and inhibiting the nuclear translocation of PKM2. In summary, this study identified CIAC001 as a lead compound in targeting PKM2 to treat morphine-induced addiction.

Ion channels in cancer-induced bone pain: from molecular mechanisms to clinical applications

Cancer-induced bone pain (CIBP) caused by bone metastasis is one of the most prevalent diseases, and current treatments rely primarily on opioids, which have significant side effects. However, recent developments in pharmaceutical science have identified several new mechanisms for CIBP, including the targeted modification of certain ion channels and receptors. Ion channels are transmembrane proteins, which are situated on biological cell membranes, which facilitate passive transport of inorganic ions across membranes. They are involved in various physiological processes, including transmission of pain signals in the nervous system. In recent years, there has been an increasing interest in the role of ion channels in chronic pain, including CIBP. Therefore, in this review, we summarize the current literature on ion channels, related receptors, and drugs and explore the mechanism of CIBP. Targeting ion channels and regulating their activity might be key to treating pain associated with bone cancer and offer new treatment avenues.

Association between body mass index and treatment completion in extended-release naltrexone-treated patients with opioid dependence

Background

Excessive consumption of opioids is associated with impaired metabolic function including increased body mass index (BMI). Opioid antagonist naltrexone (NTX) is an effective treatment for opioid use disorder (OUD) that has the potential to mitigate such metabolic disturbances. Understanding the relationship between treatment adherence and BMI in NTX-treated OUD patients may provide valuable insights into optimizing clinical outcomes.

Methods

Patients with opioid dependence were offered up to three monthly injections of extended-release (XR) NTX. Treatment completers (n = 41) were defined as those who had received all three XR-NTX injections, and non-completers (n = 20) as those missing at least one injection. Logistic regression was performed to examine the association between pre-treatment BMI and treatment completion.

Results

BMI was positively associated with treatment completion. This association remained significant after adjusting for potentially confounding variables.

Conclusion

Our findings suggest that baseline BMI may serve as a potential predictor of XR-NTX treatment adherence in patients with OUD and could help healthcare providers and policy makers alike in developing strategies to improve retention and tailor interventions for specific patient subgroups.

Correlates of Perceived Discrimination Related to Substance Use Disorders Among Patients in Methadone Maintenance Treatment

This study sought to examine demographic, treatment-related, and diagnosis-related correlates of substance use disorder (SUD)-related perceived discrimination among patients receiving methadone maintenance treatment (MMT). Participants were 164 patients at nonprofit, low-barrier-to-treatment-access MMT programs. Participants completed measures of demographics, diagnosis-related characteristics (Brief Symptom Inventory (BSI-18) and Depressive Experiences Questionnaire (DEQ)), and treatment-related characteristics. Perceived discrimination was measured on a seven-point Likert-type scale ranging from 1 ("Not at all") to 7 ("Extremely") in response to the item: "I often feel discriminated against because of my substance abuse." Given the variable's distribution, a median split was used to categorize participants into "high" and "low" discrimination groups. Correlates of high and low discrimination were analyzed with bivariate and logistic regression models. Ninety-four participants (57%) reported high SUD-related perceived discrimination. Bivariate analyses identified six statistically significant correlates of SUD-related perceived discrimination (P < .05): age, race, age of onset of opioid use disorder, BSI-18 Depression, DEQ Dependency, and DEQ Self-Criticism. In the final logistic regression model, those with high (versus low) SUD-related perceived discrimination were more likely to report depressive symptoms and be self-critical. Patients in MMT with high compared to low SUD-related perceived discrimination may be more likely to report being depressed and self-critical.

Advances in the characterization of negative affect caused by acute and protracted opioid withdrawal using animal models

Opioid use disorder (OUD) is a chronic brain disease which originates from long-term neuroadaptations that develop after repeated opioid consumption and withdrawal episodes. These neuroadaptations lead among other things to the development of a negative affect, which includes loss of motivation for natural rewards, higher anxiety, social deficits, heightened stress reactivity, an inability to identify and describe emotions, physical and/or emotional pain, malaise, dysphoria, sleep disorders and chronic irritability. The urge for relief from this negative affect is one of major causes of relapse, and thus represents a critical challenge for treatment and relapse prevention. Animal models of negative affect induced by opioid withdrawal have recapitulated the development of a negative emotional state with signs such as anhedonia, increased anxiety responses, increased despair-like behaviour and deficits in social interaction. This research has been critical to determine neurocircuitry adaptations during chronic opioid administration or upon withdrawal. In this review, we summarize the recent literature of rodent models of (i) acute withdrawal, (ii) protracted abstinence from passive administration of opioids, (iii) withdrawal or protracted abstinence from opioid self-administration. Finally, we describe neurocircuitry involved in acute withdrawal and protracted abstinence. This article is part of the Special Issue on "Opioid-induced changes in addiction and pain circuits".

Characterization of Unintentional Deaths Among Buprenorphine Users

OBJECTIVE

Medications used to treat opioid use disorder (OUD) reduce drug overdose risk. Buprenorphine is often the preferred treatment for OUD because of its high safety profile. Given expanding buprenorphine use, this study sought to examine buprenorphine-involved deaths (BIDs) and compare them with other drug-related deaths.

METHOD

West Virginia drug-related deaths from 2005 to early 2020 were identified. Study data included decedent demographics, toxicology, autopsy findings, and medical and prescription histories. Characteristics of BIDs compared with other drug-related deaths were statistically analyzed.

RESULTS

Among 11,764 drug-related deaths, only 564 (4.8%) involved buprenorphine. Buprenorphine alone was present in 32 deaths, of which 20 were considered the direct cause of death (0.2% of all drug-related deaths). Significantly more BIDs involved five or more drugs (23%) compared with other opioid deaths (14.9%). Co-intoxicants found most frequently in BIDs were benzodiazepines (47.3%), methamphetamine (27.1%), and fentanyl (22.9%). Cardiovascular and pulmonary comorbidities were identified in 43% and 21% of BIDs, respectively. Of the 564 BIDs, a current buprenorphine prescription was present in 132 deaths (23.4%).

CONCLUSIONS

Despite increasing buprenorphine use, BIDs comprised less than 5% of overall West Virginia drug-related deaths. Seldom was it the only drug found, and most decedents did not have current prescriptions for buprenorphine. Although buprenorphine is effective, with a wide safety margin, clinicians and patients should be aware that buprenorphine can be involved in overdose deaths, especially when buprenorphine is taken in combination with drugs such as benzodiazepines, methamphetamine, or fentanyl, and in persons with underlying cardiovascular or pulmonary comorbidities.

Clinical Trial Design Challenges and Opportunities for Emerging Treatments for Opioid Use Disorder: A Review

Importance

Novel treatments for opioid use disorder (OUD) are needed to address both the ongoing opioid epidemic and long-standing barriers to existing OUD treatments that target the endogenous μ-opioid receptor (MOR) system. The goal of this review is to highlight unique clinical trial design considerations for the study of emerging treatments for OUD that address targets beyond the MOR system. In November 2019, the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION) public-private partnership with the US Food and Drug Administration sponsored a meeting to discuss the current evidence regarding potential treatments for OUD, including cannabinoids, psychedelics, sedative-hypnotics, and immunotherapeutics, such as vaccines.

Observations

Consensus recommendations are presented regarding the most critical elements of trial design for the evaluation of novel OUD treatments, such as: (1) stage of treatment that will be targeted (eg, seeking treatment, early abstinence/detoxification, long-term recovery); (2) role of treatment (adjunctive with or independent of existing OUD treatments); (3) primary outcomes informed by patient preferences that assess opioid use (including changes in patterns of use), treatment retention, and/or global functioning and quality of life; and (4) adverse events, including the potential for opioid-related relapse or overdose, especially if the patient is not simultaneously taking maintenance MOR agonist or antagonist medications.

Conclusions and Relevance

Applying the recommendations provided here as well as considering input from people with lived experience in the design phase will accelerate the development, translation, and uptake of effective and safe therapeutics for individuals struggling with OUD.

Has the treatment gap for opioid use disorder narrowed in the U.S.?: A yearly assessment from 2010 to 2019"

BACKGROUND

The United States overdose crisis continues unabated. Despite efforts to increase capacity for treating opioid use disorder (OUD) in the U.S., how actual treatment receipt compares to need remains unclear. In this cross-sectional study, we estimate progress in addressing the gap between OUD prevalence and OUD treatment receipt at the national and state levels from 2010 to 2019.

METHODS

We estimated past-year OUD prevalence rates based on the U.S. National Survey on Drug Use and Health (NSDUH), using adjustment methods that attempt to account for OUD underestimation in national household surveys. We used data from specialty substance use treatment records and outpatient pharmacy claims to estimate the gap between OUD prevalence and number of persons receiving medications for opioid use disorder (MOUD) during the past decade.

RESULTS

Adjusted estimates suggest past-year OUD affected 7,631,804 individuals in the U.S. in (2,773 per 100,000 adults 12+), relative to only 1,023,959 individuals who received MOUD (365 per 100,000 adults 12+). This implies approximately 86.6% of individuals with OUD nationwide who may benefit from MOUD treatment do not receive it. MOUD receipt increased across states over the past decade, but most regions still experience wide gaps between OUD prevalence and MOUD receipt.

CONCLUSIONS

Despite some progress in expanding access to MOUD, a substantial gap between OUD prevalence and treatment receipt highlights the critical need to increase access to evidence-based services.

Sensitivity of a fentanyl-vs.-social interaction choice procedure to environmental and pharmacological manipulations

Recent studies have shown that social interaction can serve as an alternative reinforcer to opioid self-administration under a choice context in rats. However, additional parametric studies are needed to evaluate the sensitivity of opioid-vs.-social interaction procedures relative to more established opioid-vs.-food procedures. The current study evaluated the sensitivity of a novel fentanyl-vs.-social interaction choice procedure to environmental and pharmacological manipulations previously shown to affect fentanyl-vs.-food choice. Male and female rats (responder rats; n = 6/sex) were trained to respond in a discrete-trial choice procedure for either 30-s access to a same-sex "partner" rat or an intravenous fentanyl infusion. Once trained, the effects of fentanyl unit dose (0, 0.32-10 μg/kg/inf), partner rat presence, opioid-dependence status, chronic naltrexone administration (0.032, 0.1 mg/kg/h), and response requirement for fentanyl self-administration (fixed ratio 1-320) were determined across weeks. The fentanyl-vs.-social interaction choice procedure was sensitive to the unit dose of fentanyl, chronic naltrexone treatment, and fentanyl response requirement. However, the magnitude of these effects on fentanyl choice was smaller than those reported in published fentanyl-vs.-food choice studies. Furthermore, fentanyl-vs.-social interaction choice was not sensitive to removal of the partner rat or opioid-dependence status. Minimal sex differences were detected. These results suggest that this fentanyl-vs.-social interaction choice procedure is less sensitive to environmental and pharmacological interventions than previously established opioid-vs.-food choice procedures. The observed discrepancy in sensitivity between the procedures suggests that social interaction may have qualitatively different reinforcing properties compared to more commonly assessed alternative reinforcers such as food (preclinical) or money (human laboratory).

Real-world effectiveness of pharmacological treatments of opioid use disorder in a national cohort

AIM

To investigate the real-world effectiveness of pharmacological treatments (buprenorphine, methadone) of opioid use disorder (OUD).

DESIGN

A nation-wide, register-based cohort study.

SETTING

Sweden.

PARTICIPANTS

All residents aged 16-64 years living in Sweden using OUD medication from July 2005 to December 2016 (n = 5757, 71.8% men) were identified from registers of prescriptions, inpatient and specialized outpatient care, causes of death, sickness absence and disability pensions.

MEASUREMENTS

Main outcome: hospitalization due to OUD.

SECONDARY OUTCOMES

hospitalization due to any cause; death due to all, natural and external causes. Mortality was analyzed with between-individual multivariate-adjusted Cox hazards regression model. Recurrent outcomes, such as hospitalizations, were analyzed with within-individual analyses to eliminate selection bias. OUD medication use versus non-use was modelled with PRE2DUP (from prescription drug purchases to drug use periods) method.

FINDINGS

Buprenorphine [hazard ratio (HR) = 0.73, 95% confidence interval (CI) = 0.54-0.97] and methadone (HR = 0.74, 95% CI = 0.59-0.93) use were associated with significantly lower risk of OUD hospitalization, but not any-cause hospitalizations, compared with the time-periods when the same individual did not use OUD medication. The use of buprenorphine and methadone were both associated with significantly lower risk of all-cause mortality (HR = 0.45, 95% CI = 0.34-0.59; HR = 0.51, 95% CI = 0.41-0.63, respectively), compared with non-use of both medications. Similar results were found for risk of mortality due to external causes (HR = 0.39; 95% CI = 0.27-0.54; HR = 0.40; 95% CI = 0.29-0.53, respectively), but not for mortality due to natural causes. The risk of OUD hospitalization and all-cause mortality was decreased in all duration categories of studied medications (< 30, 31-180, 181-365 and >365 days), except for methadone use less than 30 days.

CONCLUSIONS

The use of buprenorphine and methadone are both associated with a significantly lower risk of hospitalization due to opioid use disorder and death due to all and external causes, when compared with non-use.

Dopamine D3 receptor ligands: a patent review (2014-2020)

INTRODUCTION

Compelling evidence identified D3 dopamine receptor (D3R) as a suitable target for therapeutic intervention on CNS-associated disorders, cancer and other conditions. Several efforts have been made toward developing potent and selective ligands for modulating signalling pathways operated by these GPCRs. The rational design of D3R ligands endowed with a pharmacologically relevant profile has traditionally not encountered much support from computational methods due to a very limited knowledge of the receptor structure and of its conformational dynamics. We believe that recent progress in structural biology will change this state of affairs in the next decade.

AREAS COVERED

This review provides an overview of the recent (2014-2020) patent literature on novel classes of D3R ligands developed within the framework of CNS-related diseases, cancer and additional conditions. When possible, an in-depth description of both in vitro and in vivo generated data is presented. New therapeutic applications of known molecules with activity at D3R are discussed.

EXPERT OPINION

Building on current knowledge, future D3R-focused drug discovery campaigns will be propelled by a combination of unprecedented availability of structural information with advanced computational and analytical methods. The design of D3R ligands with the sought activity, efficacy and selectivity profile will become increasingly more streamlined.

Life satisfaction among individuals with opioid use disorder receiving extended-release naltrexone: A 12-week randomized controlled trial and a 36-week follow-up

INTRODUCTION

Life satisfaction (LS) in opioid-dependent individuals is lower than in the general population. This study aimed to explore changes in LS during short- and long-term treatment with extended-release naltrexone (XR-NTX).

METHODS

This open-label 12-week clinical trial randomized 159 participants to either monthly XR-NTX or daily buprenorphine-naloxone (BP-NLX). In a subsequent 36-week follow-up study on XR-NTX, participants either continued or switched to XR-NTX. The study collected data on the Temporary Satisfaction with Life (TSWL) and illicit opioid use every fourth week. The research team assessed changes in TSWL by a linear mixed model and growth mixture model. The study assessed relationship between opioid use and TSWL by a linear mixed model.

RESULTS

Change in LS differed significantly between the groups in both study periods. TSWL scores were significantly higher in the XR-NTX group at week 4 (p = 0.013) and week 8 (p = 0.002). In the follow-up period, the groups were significantly different only at week 16 (p = 0.031) and week 48 (p = 0.025), with the higher TSWL scores in the XR-NTX continued group. Increase in opioid use by one day was associated with a 0.12 point lower mean TSWL score. Both study periods identified groups with low and high LS levels. In the trial period, the TSWL scores exhibited a significant increase from baseline to week 12 in both groups, p < 0.001 and p = 0.011 in the low and high LS group, respectively. In the follow-up period, the TSWL scores exhibited a significant increase from week 16 to week 48 (p = 0.003) in the high LS group, while the low LS group showed persistently lower values throughout that period.

CONCLUSIONS

XR-NTX treatment given once monthly is associated with higher LS, as measured by TSWL, compared to daily use of BP-NLX. The majority of the participants had relatively low TSWL scores and did not report any change in TSWL during longer-term treatment. The study found a significant association between more frequent illicit opioid use and a low or decreased LS during follow-up.

Recent advances in the treatment of opioid use disorders-focus on long-acting buprenorphine formulations

Oral methadone or sublingual buprenorphine are first-line medications for pharmacotherapy of opioid use disorders (OUDs). Three long-acting buprenorphine depot or implant formulations are currently available for the treatment of OUDs: (1) CAM 2038 (Buvidal) for subcutaneous weekly and monthly application; (2) RBP-6000 (Sublocade™) as a monthly depot formulation; and (3) A six-month buprenorphine implant [Probuphine™]. The pharmacology, clinical efficacy and prospects of these medications are discussed.

An examination between treatment type and treatment retention in persons with opioid and co-occurring alcohol use disorders

BACKGROUND AND AIMS

Persons with opioid use disorder (OUD) and co-occurring alcohol use disorder (AUD) are understudied. We identified whether co-occurring AUD was associated with OUD treatment type, compared associations between treatment type and six-month treatment retention and determined whether co-occurring AUD moderated these relationships.

METHODS

We used an observational cohort study design to analyze insurance claims data from 2011 to 2016 from persons aged 12-64 with an opioid abuse or opioid dependence diagnosis and OUD treatment claim. Our unit of analysis was the treatment episode; we used logistic regression for analyses.

RESULTS

Of 211,047 treatment episodes analyzed, 14 % had co-occurring alcohol abuse or dependence diagnoses. Among persons with opioid dependence, persons with co-occurring alcohol dependence were 25 % less likely to receive medication treatment relative to those without AUD. Further, alcohol dependence was associated with decreased likelihood of treatment with buprenorphine (AOR 0.47, 95 % CI 0.44-0.49) or methadone (AOR 0.31, 95 % CI 0.28-0.35) and increased likelihood of treatment with extended-release (AOR 1.36, 95 % CI 1.21-1.54) or oral (AOR 1.73, 95 % CI 1.57-1.90) naltrexone relative to psychosocial treatment. Buprenorphine and methadone were associated with highest retention prevalence regardless of OUD or AUD severity. Co-occurring alcohol abuse or dependence did not meaningfully change retention prevalence associated with buprenorphine or methadone. Co-occurring AUD was not associated with improved retention among persons receiving either formulation of naltrexone.

CONCLUSIONS

Buprenorphine and methadone are associated with relatively high likelihood of treatment retention among persons opioid and alcohol dependence, but are disproportionately under-prescribed.

Brain volume changes after long-term injectable opioid treatment: A longitudinal voxel-based morphometry study

Clinical research has demonstrated the efficacy of injectable opioid treatment for long-term, treatment-refractory opioid-dependent patients. It has been hypothesized that compulsive drug use is particularly associated with neuroplasticity changes in the networks corresponding to withdrawal/negative affect and preoccupation/anticipation rather than binge/intoxication. However, as yet, no study has investigated the effect of long-term opioid treatment on key regions within these networks. Magnetic resonance imaging (MRI) was used to assess brain volumes changes during long-term (approximately 9 years) injectable opioid agonist treatment with diacetylmorphine (DAM) in 22 patients with opioid use disorder. Voxel-based morphometry was applied to detect volumetric changes within the networks of binge/intoxication (ventral/dorsal striatum, globus pallidus and thalamus), withdrawal/negative affect (amygdala and ventral striatum) and preoccupation/anticipation (hippocampus, orbitofrontal and anterior cingulate cortex). The relationships between significant volume changes and features of opioid use disorder were tested using Pearson correlation. Long-term opioid agonist treatment was associated with the enlargement of the right caudate nucleus, which was related to the duration of opioid use disorder. In contrast, reduced volume in the right amygdala, anterior cingulate cortex and orbitofrontal cortex were found that were related to opioid dose, onset of opioid consumption and state anxiety. These findings suggest that long-term opioid agonist treatment is related to structural changes in key brain regions underlying binge/intoxication, withdrawal/negative affect and preoccupation/anticipation, suggesting sustained interaction between these systems.

Patient-Reported Outcomes of Treatment of Opioid Dependence With Weekly and Monthly Subcutaneous Depot vs Daily Sublingual Buprenorphine: A Randomized Clinical Trial

IMPORTANCE

Patient-reported outcomes in the treatment of opioid dependence may differ between subcutaneously administered depot buprenorphine and daily sublingual buprenorphine.

OBJECTIVE

To compare patient satisfaction between depot buprenorphine and sublingual buprenorphine in adult outpatients with opioid dependence.

DESIGN, SETTING, AND PARTICIPANTS

This open-label, randomized clinical trial was conducted among adult patients with opioid dependence at 6 outpatient clinical sites in Australia from October 2018 to September 2019. Data analysis was conducted from October 2019 to May 2020.

INTERVENTIONS

Participants were randomized to receive treatment with weekly or monthly depot buprenorphine or daily sublingual buprenorphine over 24 weeks.

MAIN OUTCOMES AND MEASURES

The primary end point was the difference in global treatment satisfaction, assessed by the Treatment Satisfaction Questionnaire for Medication (TSQM) version 1.4 (range, 0-100; higher score indicates greater satisfaction) at week 24. Secondary end points included other patient-reported outcomes, including quality of life, treatment burden, and health-related outcomes, as well as measures of opioid use, retention in treatment, and safety.

RESULTS

A total of 119 participants (70 [58.8%] men; mean [SD] age, 44.4 [10.5] years) were enrolled, randomized to, and received either depot buprenorphine (60 participants [50.4%]) or sublingual buprenorphine (59 participants [49.6%]). From the initial sample of 120, a participant (0.8%) in the sublingual buprenorphine group withdrew consent and did not receive study treatment. All participants were receiving sublingual buprenorphine when enrolled. The mean TSQM global satisfaction score was significantly higher for the depot group compared with the sublingual group at week 24 (mean [SE] score, 82.5 [2.3] vs 74.3 [2.3]; difference, 8.2; 95% CI, 1.7 to 14.6; P = .01). Improved outcomes were also observed for several secondary end points after treatment with depot buprenorphine (eg, mean [SE] treatment burden assessed by the Treatment Burden Questionnaire global score, on which lower scores indicate lower burden: 13.2 [2.6] vs 28.6 [2.5]; difference, -15.4; 95% CI, -22.6 to -8.2; P < .001). Thirty-nine participants (65.0%) in the depot buprenorphine group experienced 117 adverse drug reactions, mainly injection site reactions of mild intensity following subcutaneous administration, and 12 participants (20.3%) in the sublingual buprenorphine group experienced 21 adverse drug reactions. No participants withdrew from the trial medication or the trial due to adverse events.

CONCLUSIONS AND RELEVANCE

In this study, participants receiving depot buprenorphine reported improved treatment satisfaction compared with those receiving sublingual buprenorphine. The results highlight the application of patient-reported outcomes as alternative end points to traditional markers of substance use in addiction treatment outcome studies.

TRIAL REGISTRATION

anzctr.org.au Identifier: ANZCTR12618001759280.

Metabolomics reveals biomarkers of opioid use disorder

Opioid use disorder (OUD) is diagnosed using the qualitative criteria defined by the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Diagnostic biomarkers for OUD do not currently exist. Our study focused on developing objective biological markers to differentiate chronic opiate users with OUD from chronic opiate users without OUD. Using biospecimens from the Golestan Cohort Study, we compared the metabolomics profiles of high opium users who were diagnosed as OUD positive with high opium users who were diagnosed as OUD negative. High opium use was defined as maximum weekly opium usage greater than or equal to the median usage (2.4 g per week), and OUD was defined as having 2 or more DSM-5 criteria in any 12-month period. Among the 218 high opium users in this study, 80 were diagnosed as OUD negative, while 138 were diagnosed as OUD positive. Seven hundred and twelve peaks differentiated high opium users diagnosed as OUD positive from high opium users diagnosed as OUD negative. Stepwise logistic regression modeling of subject characteristics data together with the 712 differentiating peaks revealed a signature that is 95% predictive of an OUD positive diagnosis, a significant (p < 0.0001) improvement over a 63% accurate prediction based on subject characteristic data for these samples. These results suggest that a metabolic profile can be used to predict an OUD positive diagnosis.