Buprenorphine treatment for opioid use disorder: recent progress

Initiation of Buprenorphine Treatment of Opioid Use Disorder in Pediatric Emergency Departments

Pediatric emergency departments (EDs) in the United States are facing a rise in the number of children and adolescents who present with opioid use disorder (OUD), often driven by illicitly manufactured fentanyl. Medication treatment of pediatric OUD in the ED setting is often limited to symptomatic treatment of opioid withdrawal. Pediatric patients are rarely offered medications for OUD, especially in the ED setting. Buprenorphine is a partial opioid agonist that is Food and Drug Administration-approved for the treatment of OUD in patients aged 16 years and older. Adult studies have demonstrated that ED initiation of medication for OUD such as buprenorphine is feasible, safely treats withdrawal symptoms, and can improve patient compliance with outpatient follow-up. However, initiation of buprenorphine in the ED has not been well-studied in the pediatric population. We present 2 cases of adolescent patients, a 16-year-old male and 17-year-old female, who presented to the ED with opioid withdrawal. They were both diagnosed with severe OUD because of their use of counterfeit pills containing fentanyl. Both patients were successfully started on buprenorphine/naloxone in the pediatric ED before transitioning to an outpatient addiction clinic for continued treatment. The case series demonstrates the feasibility of ED-based buprenorphine initiation for adolescents, an important and timely intervention for adolescents with OUD.

Estradiol and Mu opioid-mediated reward: The role of estrogen receptors in opioid use

Opioid use and opioid use disorder are characterized by sex and gender differences, and some of these differences may be mediated by differences in the hormonal milieu within and across individuals. This review focuses on the role of ovarian hormones, and particularly estradiol, on the endogenous mu opioid receptor system. There is an abundance of data indicating that estradiol influences the activity of endogenous mu opioid peptides, the activation of mu opioid receptors, and the internalization and desensitization of mu opioid receptors. These effects have functional consequences on behaviors mediated by endogenous mu opioid receptor activity and on sensitivity to mu opioid agonists and antagonists. Recent behavioral data suggest these consequences extend to mu opioid reward, and preclinical studies report that estradiol decreases self-administration of mu opioid receptor agonists across a range of experimental conditions. Data collected in human laboratory studies suggest that estradiol may have functionally similar effects in clinical populations, and thus estrogen receptors may be a potential target in the development of novel therapeutics. This review summarizes data from cellular assays to clinical trials to explore how estradiol influences mu opioid receptor activity, as well as potential ways in which estrogen receptors may be targeted to address the problems of opioid use.

Higher buprenorphine dose associated with increased treatment retention at low threshold buprenorphine clinic: A retrospective cohort study

INTRODUCTION

Controversy exists regarding effective sublingual buprenorphine dosing for treatment of opioid use disorder (OUD), leading to dose caps of 16 mg per day. The Project Connections at Re-Entry (PCARE) program is a low-threshold buprenorphine clinic that provides medication for OUD to vulnerable populations in Baltimore City.

OBJECTIVES

To compare retention in care based on treatment dose of buprenorphine, and to examine associated population characteristics.

METHODS

This analysis includes clinical patients who received buprenorphine treatment at PCARE between January and July 2021. The study categorized patients into two dosing groups (16 mg or >16 mg). We conducted chi-square tests of independence for categorical variables and independent sample t-tests for continuous variables to evaluate any significant differences in demographic and clinical characteristics by dosing category. To examine differences in 30- and 90-day retention, we conducted multivariable logistic regression analyses with the outcome variable defined as successful retention (at 30 and 90 days, respectively) controlling for demographic and clinical characteristics.

RESULTS

In the study period, 566 patients received buprenorphine treatment at the PCARE van. Patients were primarily male (70.9 %), Black (89.4 %), had a mean age of 46.3 years (SD = 11.5), and a mean opioid use of 22.1 years (SD = 13.5). The majority had previous criminal justice involvement (73.9 %), Medicaid insurance coverage (75.4 %), and were unemployed (69.6 %). Nearly half of the sample had reported a previous overdose event (48.4 %). The study found no significant demographic differences between patients receiving 16 mg of buprenorphine per day compared to patients receiving >16 mg. Patients receiving >16 mg had significantly higher rates of treatment retention at 30 and 90 days: 95.4 % vs 86.7 % (p = 0.001), and 82.7 % vs. 67.6 % (p < 0.001) than those receiving 16 mg, respectively. In a multivariable logistic regression controlling for demographic and drug use characteristics, odds of 30-day (Adjusted Odds Ratio [AOR] = 3.98, 95 % Confidence Interval [CI] = 1.92, 8.74, p < 0.001) and 90-day retention (AOR = 2.56, 95 % CI = 1.55, 4.22, p < 0.001) were greater among patients receiving >16 mg daily compared to 16 mg.

CONCLUSIONS

In this study examining patients with OUD in a low-threshold buprenorphine clinic, we observed higher rates of treatment retention with buprenorphine doses >16 mg.

In-vitro and in-vivo evaluation of sustained-release buprenorphine using in-situ forming lipid-liquid crystal gels

AIMS

Sustained-release systems reduce the incidence of drug side effects and the need for frequent drug consumption, thus increasing patient compliance with treatment. In this study, we aimed to produce sustained-release buprenorphine (BP) using lipid-liquid crystal gels.

MAIN METHODS

The three experimental groups in this study included: group I: lipid-liquid crystal formulation 5 (F5) containing BP, group II: BP-free F5, group III: BP solution in NMP, and group IV: control (no treatment). The formulations were injected subcutaneously into the rabbits' back neck.

KEY FINDINGS

The results showed that the time required to reach the drug's maximum concentration (T_max) was longer in group I than in group III. The maximum BP concentration (C_max) and the constants of the drug removal rate and drug absorption rate (K_a) were significantly higher in group III compared to group I. The half-life (t_1/2) of the drug in blood circulation was significantly longer in group I than in group III. Histopathological analysis revealed no histological abnormalities in the skin and heart in group I (BP-containing F5); however, mild hyperemia was observed in interstitial vessels in group III (BP-containing NMP). The kidney and liver tissues showed normal structure in the control group, as well as groups I and II. However, in the group receiving BP-containing NMP, significant congestion, tissue damage, necrosis, and fibrosis were observed in the kidney and liver.

SIGNIFICANCE

The results showed that the lipid-liquid crystal system can be used to design slow-release platforms for BP, minimizing the side effects associated with the use of its conventional forms.

Bridging the Macro-micro Divide: A Qualitative Meta-synthesis on the Perspectives and Experiences of Health Care Providers on the Extramedical Use and Diversion of Buprenorphine

OBJECTIVES

Opioid agonist therapy using buprenorphine is one of the most effective treatments for opioid use disorder. However, concerns regarding its extramedical use and diversion, such as adverse patient outcomes and damage to the legitimacy of addictions practice, are persistent. The aim of this review is to synthesize the perspectives and experiences of health care providers around the extramedical use of buprenorphine.

METHODS

A qualitative meta-synthesis was conducted based on a systematic search of 8 databases. All primary qualitative and mixed-methods studies relating to the views of health care providers on the extramedical use of buprenorphine were included. A qualitative analysis informed by the constant comparative method was conducted, using NVivo for data management.

RESULTS

Sixteen studies were included in this review. Findings were organizedunder 2 key themes: (1) Harm-producing versus harm-reducing effects of extramedical buprenorphine use and (2) driving forces of and responses to extramedical buprenorphine use.

CONCLUSIONS

The studies included in our review identified a disconnect-health care providers noted that macro, health care system-level challenges drove extramedical use whereas the recommended solutions for prevention and management were primarily aimed at the micro, individual level. This study emphasizes the critical role that health care providers can play, in partnership with patients, in informing appropriate policies and health care system design to optimize the care for people with opioid use disorder.

Endogenous opioid systems alterations in pain and opioid use disorder

Decades of research advances have established a central role for endogenous opioid systems in regulating reward processing, mood, motivation, learning and memory, gastrointestinal function, and pain relief. Endogenous opioid systems are present ubiquitously throughout the central and peripheral nervous system. They are composed of four families, namely the μ (MOPR), κ (KOPR), δ (DOPR), and nociceptin/orphanin FQ (NOPR) opioid receptors systems. These receptors signal through the action of their endogenous opioid peptides β-endorphins, dynorphins, enkephalins, and nociceptins, respectfully, to maintain homeostasis under normal physiological states. Due to their prominent role in pain regulation, exogenous opioids-primarily targeting the MOPR, have been historically used in medicine as analgesics, but their ability to produce euphoric effects also present high risks for abuse. The ability of pain and opioid use to perturb endogenous opioid system function, particularly within the central nervous system, may increase the likelihood of developing opioid use disorder (OUD). Today, the opioid crisis represents a major social, economic, and public health concern. In this review, we summarize the current state of the literature on the function, expression, pharmacology, and regulation of endogenous opioid systems in pain. Additionally, we discuss the adaptations in the endogenous opioid systems upon use of exogenous opioids which contribute to the development of OUD. Finally, we describe the intricate relationship between pain, endogenous opioid systems, and the proclivity for opioid misuse, as well as potential advances in generating safer and more efficient pain therapies.

Education as drug policy: A realist synthesis of continuing professional development for opioid agonist therapy

BACKGROUND

Continuing professional development (CPD) for opioid agonist therapy (OAT) has been identified as a key health policy strategy to improve care for people living with opioid use disorder (OUD) and to address rising opioid-related harms. To design and deliver effective CPD programs, there is a need to clarify how they work within complex health system and policy contexts. This review synthesizes the literature on OAT CPD programs and educational theory to clarify which interventions work, for whom, and in what contexts.

METHODS

A systematic review and realist synthesis of evaluations of CPD programs focused on OAT was conducted. This included record identification and screening, theory familiarization, data collection, analysis, expert consultation, and iterative context-intervention-mechanism-outcome (CIMO) configuration development.

RESULTS

Twenty-four reports comprising 21 evaluation studies from 5 countries for 3373 providers were reviewed. Through iterative testing of included studies with relevant theory, five CIMO configurations were developed. The programs were categorized by who drove the learning outcomes (i.e., system/policy, instructor, learner) and their spheres of influence (i.e., micro, meso, macro). There was a predominance of instructor-driven programs driving change at the micro level, with few policy-driven macro-influential programs, inconsistent with the promotion of CPD as a clear opioid crisis policy-level intervention.

CONCLUSION

OAT CPD is challenged by mismatches in program justifications, objectives, activities, and outcomes. Depending on how these program factors interact, OAT CPD can operate as a barrier or facilitator to OUD care. With more deliberate planning and consideration of program theory, programs more directly addressing diverse learner and system needs may be developed and delivered. OAT CPD as drug policy does not operate in isolation; programs may feed into each other and intercalate with other policy initiatives to have micro, meso, and macro impacts on educational and population health outcomes.

Can a new formulation of opiate agonist treatment alter stigma?: Place, time and things in the experience of extended-release buprenorphine depot

INTRODUCTION

Stigma has corrosive effects on all aspects of care and can undermine individual and population health outcomes. Addiction-related stigma has implications for opiate agonist treatment (OAT) and the people who receive, provide and fund it. It is important to understand how stigma is made in OAT and the political purposes that it serves, in order to change the relations of stigma and avoid the reproduction of stigma in the delivery of new treatment formulations, such as extended release buprenorphine (BUP-XR).

METHODS

Semi-structured qualitative interviews were conducted at two time points with participants in a prospective single-arm, multicentre, open-label trial of monthly BUP-XR. Thirty-six participants (25 men, 11 women) were interviewed, and of these 32 participated in a second interview to explore their experience of transition from other treatment to BUP-XR.

RESULTS

Participants were highly aware of the of the social and material effects of stigma through the negative stereotypes attached to OAT and those who receive it. Participants narrated examples of how stigma governed as a biopower in the relations and practices of OAT provision at numerous levels: structural (such as in public discourse about OAT and the people who receive it, in media, in perceptions about the decisions of investment in medical technologies); organisational (policies about legitimate access to OAT); interpersonal (with health workers) and individual (self-identities). BUP-XR allowed greater freedom and normalcy for clients. The experience of BUP-XR drew attention to the stigmatising potential of time, place and things associated with other OAT requiring daily (or frequent) dosing, accentuating how stigma comes to be materialised as a relational effect of everyday practices.

CONCLUSIONS

Receiving BUP-XR allowed participants to avoid some of the everyday biopolitical powers of other forms of OAT and to reshape self-identities. The altering of relations between time, place and things associated with other forms of OAT allowed participants to feel as though they "pass as normal" . However, the negative public discourse and stigma of OAT is a potential threat to BUP-XR to realise its potential for individual and population benefits.

Multicenter Observational/Exploratory Study Addressed to the Evaluation of the Effectiveness and Safety of Pharmacological Therapy in Opioid-Dependent Patients in Maintenance Therapy in Southern Italy

A multicenter-observational study was performed to assess the effectiveness of rac-methadone, levomethadone, and buprenorphine in opioid-dependent patients in polytherapy in Southern Italy. The primary endpoint was the reduction of urinary positivity to the substances and the maintaining doses. Patients (N = 266, age = 44.80 ± 5.65, male = 79.70%, female = 20.30%) have been recruited. At recruitment, 75% of them were on treatment with rac-methadone, levomethadone, and buprenorphine/naloxone. The patients were grouped into three clusters. The levomethadone patients of Cluster A (N patients = 211), after 180 days, showed stability in urinary methadone positivity, with a marked decrease in heroin −53 ± 4%, cannabinol’s −48 ± 2%, and cocaine −37 ± 6% positivity, with no differences between treatments. A lower QTcF value of 426 ± 8.4 ms was recorded in the levomethadone patients (delta = −19 ms) vs. rac-methadone, at significantly lower doses of levomethadone (−34%, −50.2% in males) (p < 0.05). The Cluster B data were collected from 37 patients, with a high prevalence of comorbidity infections (HIV/HCV/HPV), monitored for 21 months during COVID-19. High doses of levomethadone (58.33 ± 31.58 mg/day) were needed to stabilize those that were negative for opioids and cannabinoids, in contrast to the rac-methadone and buprenorphine/naloxone patients that showed positive toxicology. Eighteen patients of the Cluster C in double diagnosis (major depressive 38.90%, bipolar 27.78%, and schizophrenia 16.67%) were stabilized with high doses of racemate 97.5 ± 8 mg/day, 51.8 ± 5 mg/day of levomethadone (−46.8% vs. rac-methadone; −71% in men), and 2.5 ± 1 mg/day of buprenorphine/naloxone. Three patients in remission were treated with tapering doses of levomethadone. Significantly reduced QTcF values were recorded with levomethadone (delta −32 ms vs. rac-methadone) in the bipolar patients, as well as the schizophrenia patients in remission (delta −45.19 ms vs. rac-methadone). Our patients were safely stabilized. Levomethadone, compared to the racemate, contributes to reducing the illicit use, especially of opioids and cannabinoids at significantly lower doses with cardiovascular safety, which, in bipolar patients, is clinically significant.

Opioid-induced analgesia among persons with opioid use disorder receiving methadone or buprenorphine: A systematic review of experimental pain studies

BACKGROUND

Treating acute pain among persons with opioid use disorder (OUD) on opioid agonist therapy (OAT) is complex, and the therapeutic benefits of opioids remain unclear when weighted against their abuse potential and respiratory depressant effects.

METHODS

We conducted a systematic review of experimental pain studies examining opioid-induced analgesia among persons with OUD on OAT. We searched multiple databases from inception to July 30, 2021. Study quality was assessed by previously established validity measures.

RESULTS

Nine studies were identified, with a total of 225 participants, of whom 63% were male, and 37% were female. Six studies included methadone-maintained persons with OUD; four studies included buprenorphine-maintained persons with OUD; and three studies included healthy persons as comparison groups. Either additional doses of OAT or other opioids - morphine, oxycodone, hydromorphone, or remifentanil - were administered. In seven studies, persons with OUD on OAT did not experience analgesia, despite receiving opioid doses up to 20 times greater than those clinically used to treat severe pain among the opioid naïve. Conversely, in two studies, high-potency opioids did produce analgesia, albeit with greater abuse potential. Notably, persons with OUD on OAT remained vulnerable to respiratory depression.

CONCLUSIONS

Although persons with OUD on OAT can derive analgesic effects from opioids, high-potency compounds may be required to achieve clinically significant pain relief. Further, persons with OUD on OAT may remain vulnerable to opioid-induced abuse potential and respiratory depression. Together, these finding have clinical, methodological, and mechanistic implications for the treatment of acute pain in the context of OAT.

Economic Evaluations of Pharmacologic Treatment for Opioid Use Disorder: A Systematic Literature Review

OBJECTIVE

The crisis of opioid use puts a strain on resources in the United States and worldwide. There are 3 US Food and Drug Administration-approved medications for treatment of opioid use disorder: methadone, buprenorphine, and injectable extended-release naltrexone (XR-NTX). The comparative effectiveness and cost vary considerably among these 3 medications. Economic evaluations provide evidence that help stakeholders efficiently allocate scarce resources. Our objective was to summarize recent health economic evidence of pharmacologic treatment of opioid use disorder interventions.

METHODS

We searched PubMed for peer-reviewed studies in English from August 2015 through December 2019 as an update to a 2015 review. We used the Drummond checklist to evaluate and categorize economic evaluation study quality. We summarized results by economic evaluation methodology and pharmacologic treatment modality.

RESULTS

We identified 105 articles as potentially relevant and included 21 (4 cost-offset studies and 17 cost-effectiveness/cost-benefit studies). We found strengthened evidence on buprenorphine and methadone, indicating that these treatments are economically advantageous compared with no pharmacotherapy, but found limited evidence on XR-NTX. Only half of the cost-effectiveness studies used a generic preference-based measure of effectiveness, limiting broad comparison across diseases/disorders. The disease/disorder-specific cost-effectiveness measures vary widely, suggesting a lack of consensus on the value of substance use disorder treatment.

CONCLUSION

We found studies that provide new evidence supporting the cost-effectiveness of buprenorphine compared with no pharmacotherapy. We found a lack of evidence supporting superior economic value for buprenorphine versus methadone, suggesting that both are attractive alternatives. Further economic research is needed on XR-NTX, as well as other emerging pharmacotherapies, treatment modalities, and dosage forms.

Kappa Opioid Signaling at the Crossroads of Chronic Pain and Opioid Addiction

Pain is complex and is a unique experience for individuals in that no two people will have exactly the same physiological and emotional response to the same noxious stimulus or injury. Pain is composed of two essential processes: a sensory component that allows for discrimination of the intensity and location of a painful stimulus and an emotional component that underlies the affective, motivational, unpleasant, and aversive response to a painful stimulus. Kappa opioid receptor (KOR) activation in the periphery and throughout the neuroaxis modulates both of these components of the pain experience. In this chapter we focus on recent findings that KORs contribute to the emotional, aversive nature of chronic pain, including how expression in the limbic circuitry contributes to anhedonic states and components of opioid misuse disorder. While the primary focus is on preclinical pain models, we also highlight clinical or human research where there is strong evidence for KOR involvement in negative affective states associated with chronic pain and opioid misuse.

Rise and regional disparities in buprenorphine utilization in the United States

PURPOSE

Buprenorphine is an opioid partial agonist used to treat opioid use disorder. While several policy changes have attempted to increase buprenorphine availability, access remains well below optimal levels. This study characterized how buprenorphine utilization in the United States has changed over time and whether there are regional disparities in distribution of the medication.

METHODS

The amount of buprenorphine distributed from 2007 to 2017 was obtained from the Drug Enforcement Administration's Automated Reports and Consolidated Ordering System. Data were expressed as the percent change and milligrams per person in each state. The formulations and cost for prescriptions covered by Medicaid (2008 to 2018) were also examined.

RESULTS

Buprenorphine distributed to pharmacies increased about 7-fold (476.8 to 3179.9 kg) while the quantities distributed to hospitals grew 5-fold (18.6 to 97.6 kg) nationally from 2007 to 2017. Buprenorphine distribution per person was almost 20-fold higher in Vermont (40.4 mg/person) relative to South Dakota (2.1 mg/person). There was a strong association between the number of physicians authorized to prescribe buprenorphine and distribution per state (r[49] = +0.94, P < .0005). The buprenorphine/naloxone sublingual film (Suboxone) was the predominant formulation (92.6% of 0.31 million Medicaid prescriptions) in 2008 but accounted for less than three-fifth (57.3% of 6.56 million prescriptions) in 2018.

CONCLUSIONS

Although buprenorphine availability has substantially increased over the last decade, distribution was very nonhomogeneous across the United States.