Open-label dose-finding trial of buprenorphine implants (Probuphine) for treatment of heroin dependence

Evaluating preferences for medication formulation and treatment model among people who use opioids non-medically: A web-based cross-sectional study

INTRODUCTION

Over the past decade, treatment for opioid use disorder has expanded to include long-acting injectable and implantable formulations of medication for opioid use disorder (MOUD), and integrated treatment models systematically addressing both behavioral and physical health. Patient preference for these treatment options has been underexplored. Gathering data on OUD treatment preferences is critical to guide the development of patient-centered treatment for OUD. This cross-sectional study assessed preferences for long-acting MOUD and integrated treatment using an online survey.

METHODS

An online Qualtrics survey assessed preferences for MOUD formulation and integrated treatment models. The study recruited participants (n = 851) in October and November 2019 through advertisements or posts on Facebook, Google AdWords, Reddit, and Amazon Mechanical Turk (mTurk). Eligible participants scored a two or higher on the opioid pain reliever or heroin scales of the Tobacco, Alcohol Prescription Medication and other Substance Use (TAPS) Tool. Structured survey items obtained patient preference for MOUD formulation and treatment model. Using stated preference methods, the study assessed preference via comparison of preferred options for MOUD and treatment model.

RESULTS

In the past year, 824 (96.8 %) participants reported non-prescribed use of opioid pain relievers (mean TAPS score = 2.72, SD = 0.46) and 552 (64.9 %) reported heroin or fentanyl use (mean TAPS score = 2.73, SD = 0.51). Seventy-four percent of participants (n = 631) reported currently or previously receiving OUD treatment, with 407 (48.4 %) receiving MOUD. When asked about preferences for type of MOUD formulation, 452 (53.1 %) preferred a daily oral formulation, 115 (13.5 %) preferred an implant, 114 (13.4 %) preferred a monthly injection and 95 (11.2 %) preferred a weekly injection. Approximately 8.8 % (n = 75) would not consider MOUD regardless of formulation. The majority of participants (65.2 %, n = 555) preferred receiving treatment in a specialized substance use treatment program distinct from their medical care, compared with receiving care in an integrated model (n = 296, 34.8 %).

CONCLUSIONS

Though most participants expressed willingness to try long-acting MOUD formulations, the majority preferred short-acting formulations. Likewise, the majority preferred non-integrated treatment in specialty substance use settings. Reasons for these preferences provide insight on developing effective educational tools for patients and suggesting targets for intervention to develop a more acceptable treatment system.

Nalmefene Hydrochloride: Potential Implications for Treating Alcohol and Opioid Use Disorder

Nalmefene hydrochloride was first discovered as an opioid antagonist derivative of naltrexone in 1975. It is among the most potent opioid antagonists currently on the market and is differentiated from naloxone and naltrexone by its partial agonist activity at the kappa-opioid receptor which may benefit in the treatment of alcohol use disorder. Oral nalmefene has been approved in the European Union for treatment of alcohol use disorder since 2013. As of 2023, nalmefene is available in the United States as an intranasal spray for reversal of opioid overdose but is not approved for alcohol or opioid use disorder as a maintenance treatment. The substantially longer half-life of nalmefene and 5-fold higher binding affinity to opioid receptors makes it a superior agent over naloxone in the reversal of high potency synthetic opioids like fentanyl and the emerging nitazenes. Nalmefene presents with a comparable side effect profile to other opioid antagonists and should be considered for further development as a maintenance treatment for opioid and other substance use disorders.

Buprenorphine for Chronic Pain Management: a Narrative Review

PURPOSE OF REVIEW

The aim of this review is to educate healthcare professionals regarding buprenorphine for the use of opioid use disorder (OUD) as well as for chronic pain management. This review provides physicians and practitioners with updated information regarding the distinct characteristics and intricacies of prescribing buprenorphine.

RECENT FINDINGS

Buprenorphine is approved by the US Food and Drug Administration (FDA) for acute pain, chronic pain, opioid use disorder (OUD), and opioid dependence. When compared to most other opioids, buprenorphine offers superior patient tolerability, an excellent half-life, and minimal respiratory depression. Buprenorphine does have notable side effects as well as pharmacokinetic properties that require special attention, especially if patients require future surgical interventions. Many physicians are not trained to initiate or manage patients on buprenorphine. However, buprenorphine offers a potentially safer alternative for medication management for patients who require chronic opioid therapy for pain or have OUD. This review provides updated information on buprenorphine for both chronic pain and OUD.

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

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

Buprenorphine and its formulations: a comprehensive review

Buprenorphine, a novel long-acting analgesic, was developed with the intention of two purposes: analgesia and opioid use disorder. Regarding its pharmacodynamics, it is a partial agonist at mu receptors, an inverse agonist at kappa receptors, and an antagonist at delta receptors. For the purpose of analgesia, three formulations of buprenorphine were developed: IV/IM injectable formulation (Buprenex®), transdermal patch formulation (Butrans®), and buccal film formulation (Belbuca®). Related to opioid dependence, the formulations developed were subcutaneous extended release (Sublocade®), subdermal implant (Probuphine®), and sublingual tablets (Subutex®). Lastly, in order to avoid misuse of buprenorphine for opioid dependence, two combination formulations paired with naloxone were developed: film formulation (Suboxone®) and tablet formulation (Zubsolv®). In this review, we present details of each formulation along with their similarities and differences between each other and clinical considerations.

Control Release and Diffusion-Reaction Kinetics of Genipin-Eluting Fibers Using an in Vitro Aneurysm Flow Model

The minimally invasive treatment of intracranial aneurysms by endovascular coiling is attractive yet faces challenges related to the degradation of fibrin clots in the aneurysm sac over time. Fibrin gels cross-linked with genipin exhibit enhanced mechanical and chemical stability, but there are many unknowns related to best practices for delivery from endovascular devices and subsequent integration of cross-linkers with the nascent clot. Here, we describe the in vitro characterization of genipin-eluting polymer fibers prepared by coextrusion with poly(ethylene-co-vinyl acetate). Genipin incorporation and release from these fibers are characterized by various gravimetric and spectroscopic techniques. Genipin release adheres to Higuchi kinetics with Higuchi constants varying between (2.44 ± 0.83) × 10^-7 and (8.41 ± 0.82) × 10^-7 mol·h^-0.5 depending on genipin loading and vinyl acetate concentration in the polymer matrix. The diffusion-reaction kinetics of genipin released from polymeric fibers within fibrin hydrogels was investigated using an in vitro aneurysm flow model. Spatiotemporal maps of genipin cross-linking density in fibrin gels produced by absorbance measurements suggest that genipin cross-link concentrations up to 9,993.87 ± 909.01 μM can be achieved. This work describes relevant diffusion-reaction parameters of genipin in fibrin gels and establishes the viability of genipin-eluting fibers as a platform for improving endovascular embolization of intracranial aneurysms.

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.

Buprenorphine implants: a model for expedited development and approval of new drugs

Regulations for new drug approvals require stringent safety testing and efficacy trial programs. The approval process for generic drugs, however, is significantly streamlined. Bioavailability data can substitute for new rounds of efficacy trials, thereby both decreasing time to approval and reducing the costs required for new studies. This regulatory choice has not been available when generic drugs are offered in a controlled release format such as a subcutaneous depot, transdermal patch or implant. The purpose of this review is to suggest that the approval of generic drugs in inert controlled release envelopes should be eligible for similar regulatory relief. Proof for this concept is provided by the example of the numerous controlled release buprenorphine products. Buprenorphine is a generic opioid used since the 1980s in tablet form to treat pain and to treat opioid addiction. Long-acting, inert delivery vehicles for the drug have become available for the same indications. Safety and bioavailability profiles of the long-acting products are the same or improved over the parent product. A review of the long-acting drugs provides compelling evidence to recommend that generic drug-controlled release products may be eligible for alternative regulatory programs.

Novel Long-Acting Buprenorphine Medications for Opioid Dependence: Current Update

Opioid maintenance treatment with oral methadone or sublingual buprenorphine is the first-line treatment in opioid dependence. Three novel long-acting buprenorphine formulations have been approved or will be available soon: for subcutaneous weekly and monthly application, the depot formulations CAM 2038 (Buvidal^®), the monthly depot formulation RBP-6000 (Sublocade™), and a 6-month buprenorphine implant (Probuphine™). Clinical data available so far on the efficacy of these 3 medications are given, and possible clinical implications are discussed.

A systematic review of patients' and providers' perspectives of medications for treatment of opioid use disorder

BACKGROUND

The opioid epidemic is a public health crisis. Medications for opioid use disorder (MOUD) include: 1) buprenorphine, 2) methadone, and 3) extended-release naltrexone (XR-NTX). Research should investigate patients' and providers' perspectives of MOUD since they can influence prescription, retention, and recovery.

METHODS

This systematic review focused on patients' and providers' perceptions of MOUD. The review eligibility criteria included inclusion of the outcome of interest, in English, and involving persons ≥18 years. A PubMed database search yielded 1692 results; we included 152 articles in the final review.

RESULTS

There were 63 articles about buprenorphine, 115 articles about methadone, and 16 about naltrexone. Misinformation and stigma associated with MOUD were common patient themes. Providers reported lack of training and resources as barriers to MOUD.

CONCLUSION

This review suggests that patients have significant misinformation regarding MOUD. Due to the severity of the opioid epidemic, research must consider the effects of patients' and providers' perspectives on treatment for OUD, including the effects on the type of MOUD prescribed, patient retention and adherence, and ultimately the number of patients treated for OUD, which will aid in curbing the opioid epidemic.

A Literature Review Examining Primary Outcomes of Medication Treatment Studies for Opioid Use Disorder: What Outcome Should Be Used to Measure Opioid Treatment Success?

BACKGROUND AND OBJECTIVES

Medications for opioid use disorder (MOUD) reduce opioid use and overdose; however, MOUD clinical trials have used varying primary outcomes to document treatment success. We conducted a literature review to assess and critically examine the methodologies used in MOUD treatment studies.

METHODS

Published studies in English that examined MOUD (buprenorphine, methadone, or extended-release naltrexone) were included (N = 20). The methods and frequencies of measuring primary opioid outcomes, including urine drug tests (UDTs) and self-report of opioid use were compared among studies.

RESULTS

A total of 20 studies fit the inclusion criteria. Each study assessed opioid use; only 12 had opioid use as a primary outcome. Other primary outcomes included retention in treatment (N = 6), and two had other primary outcomes (death and opioid withdrawal symptoms). Opioid use was assessed through both self-report and UDTs in 15 studies. Two studies did not use UDTs. Differences were found in the methods used for how opioid use, retention in treatment, self-report of opioid use, and UDTs were measured.

DISCUSSION AND CONCLUSIONS

The different primary outcomes used and operational definitions in each study make comparisons between studies difficult. The use of both self-report and UDTs for opioid use has several advantages, and if possible, researchers should use both measures.

SCIENTIFIC SIGNIFICANCE

This is the first review critically examining outcome measures from MOUD treatment studies. Creating a standard for opioid treatment outcomes in MOUD studies will allow for generalizable results that can inform both researchers and clinicians to better care for those with OUD. (Am J Addict 2020;00:00-00).

Perceptions and preferences for long-acting injectable and implantable medications in comparison to short-acting medications for opioid use disorders

Aim

Treatment for opioid use disorders has recently evolved to include long-acting injectable and implantable formulations of medications for opioid use disorder (MOUD). Incorporating patient preferences into treatment for substance use disorders is associated with increased motivation and treatment satisfaction. This study sought to assess treatment preferences for long-acting injectable and implantable MOUD as compared to short-acting formulations among individuals with OUD.

Methods

We conducted qualitative, semi-structured telephone interviews with forty adults recruited from across the United States through Craigslist advertisements and flyers posted in treatment programs. Eligible participants scored a two or greater on the heroin or opioid pain reliever sections of the Tobacco, Alcohol, Prescription Medications, and Other Substances (TAPS) Tool, indicative of a past-year OUD. Interviews were transcribed, coded, and thematically analyzed.

Results

Twenty-four participants (60%) currently or previously had been prescribed MOUD. Sixteen participants (40%) expressed general opposition to MOUD, citing concerns that MOUD is purely financial gain for pharmaceutical companies and/or a "band aid" solution replacing one drug with another, rather than a path to abstinence. Some participants expressed personal preference for long-acting injectable (n = 16/40: 40%) and implantable formulations (n = 12/40: 30%) over short-acting formulations. About half of the participants were not willing to use injectables (n = 19/40: 48%) or implantables (n = 22/40: 55%), preferring short-acting formulations. Mixed evaluations of long- and short-acting MOUD focused on considerations of medication-related beliefs (privacy, concern over an embedded foreign body), the medication-related burden (convenience, provision of structure and support, medication administration, potential side effects), and medication-taking practices (potential for non-prescribed use, control over dosage, and duration of treatment).

Conclusions

Though many participants personally prefer short-acting to long-acting MOUD, some were open to including long-acting formulations in the range of options for those with OUD. Participants felt long-acting formulations may reduce medication-related burden and the risk of diversion. Conversely, participants expressed concern about invasive administration and loss of control over their treatment. Results suggest support for expanded access to a variety of formulations of MOUD. The use of shared decision making may also help patients select the formulation best aligned with their experiences, values, and treatment goals.

Clinical Trials for Opioid Use Disorder

This chapter describes recent clinical trials for opioid use disorder (OUD), an area that has rapidly accelerated in response to the opioid overdose crisis in the USA and newly appropriated funding. Trials involve a wide range of compounds including cannabinoids and psychedelics, new and existing compounds targeting domains emerging from addiction neuroscience, agents repurposed from other indications, and novel strategies including vaccines, enzymes, and other biologicals. In parallel, new formulations of existing compounds offer immediate promise, as do a variety of web-based interventions and smartphone-delivered apps. Trials focused on implementing existing effective interventions in mainstream healthcare settings, and others focused on special populations, e.g., adolescents, criminal justice, pregnant women, native Americans, etc., have the potential to vastly expand treatment in the near term. Given the range of ongoing and recent trials, this chapter is not intended to be an exhaustive review but rather to present an overview of approaches within the framework of the opioid treatment cascade and the context of current OUD pharmacotherapies.

Depot Buprenorphine Injection In The Management Of Opioid Use Disorder: From Development To Implementation

Buprenorphine has pharmacologic advantages over methadone, especially buprenorphine's better safety profile. The true significance of buprenorphine's introduction lies in returning the care of those suffering from opioid use disorder (OUD) to the hands of the physician. The clinical success of buprenorphine has been meager, in part because most physicians have not been exposed to treating these patients. For physicians inclined to treat OUD, the barriers to buprenorphine's implementation have been onerous and largely counter to the norms of medical practice. Some notable concerns pertain to buprenorphine's clinical pharmacology like street diversion, unintended use and accidental poisoning. Recently, injectable buprenorphine preparations have been introduced to mitigate these latter shortcomings. Yet, the injectable preparations' clinical and commercial success has fallen far short of expectation. Here, we review the clinical pharmacology of these products and their expected clinical advantages for the manufacturers, clinicians, policy makers and patients, and offer our perspective, as clinicians and researchers, on how things can improve. Questions remain whether clinicians are willing to overcome barriers to treat OUD using these medications.

Buprenorphine treatment formulations: Preferences among persons in opioid withdrawal management

BACKGROUND

In the current study, we examined factors predicting willingness to receive buprenorphine treatment and preferences for various buprenorphine formulations (oral, injection, implant) among persons in opioid withdrawal management.

METHODS

Participants were three hundred thirty-eight persons entering brief inpatient opioid withdrawal management programs at two sites. We used t-tests and Pearson χ2 - tests of independence to compare participants willing and unwilling to be prescribed buprenorphine in the future. Among persons willing to receive buprenorphine, we used multinomial logistic regression to estimate the adjusted effects of potential correlates of type of buprenorphine formulation preferred.

RESULTS

Participants averaged 33.9 (±9.5) years of age, 70.4% were male, 82.8% were White, and 11.0% were Latino/a. In all, 55.6% of participants had been prescribed buprenorphine in the past, and 54.7% were willing to use prescribed buprenorphine in the future. Those reporting past month illicit buprenorphine use and prior overdose were more willing to use prescribed buprenorphine. Of these (n = 180), most preferred daily buprenorphine formulations (tablet or film) (48.6%) over a weekly or monthly injection (23.1%) or bi-annual implant (28.3%).

CONCLUSIONS

Past buprenorphine prescription does not predict future willingness to restart. Among those willing to use buprenorphine, newer formulations of buprenorphine appealed to more than half of the participants.

Advances in the delivery of buprenorphine for opioid dependence

Opioid use disorders (OUDs) have long been a global problem, but the prevalence rates have increased over 20 years to epidemic proportions in the US, with concomitant increases in morbidity and all-cause mortality, but especially opioid overdose. These increases are in part attributable to a several-fold expansion in the prescription of opioid pain medications over the same time period. Opioid detoxification and psychosocial treatments alone have each not yielded sufficient efficacy for OUD, but μ-opioid receptor agonist, partial agonist, and antagonist medications have demonstrated the greatest overall benefit in OUD treatment. Buprenorphine, a μ-opioid receptor partial agonist, has been used successfully on an international basis for several decades in sublingual tablet and film preparations for the treatment of OUD, but the nature of formulation, which is typically self-administered, renders it susceptible to nonadherence, diversion, and accidental exposure. This article reviews the clinical trial data for novel buprenorphine delivery systems in the form of subcutaneous depot injections, transdermal patches, and subdermal implants for the treatment of OUD and discusses both the clinical efficacy of longer-acting formulations through increasing consistent medication exposure and their potential utility in reducing diversion. These new delivery systems also offer new dosing opportunities for buprenorphine and strategies for dosing intervals in the treatment of OUD.

Cost-effectiveness of subdermal implantable buprenorphine versus sublingual buprenorphine to treat opioid use disorder

AIMS

Subdermal implantable buprenorphine (BSI) was recently approved to treat opioid use disorder (OUD) in clinically-stable adults. In the pivotal clinical trial, BSI was associated with a higher proportion of completely-abstinent patients (85.7% vs 71.9%; p = .03) vs sublingual buprenorphine (SL-BPN). Elsewhere, relapse to illicit drug use is associated with diminished treatment outcomes and increased costs. This study evaluated the cost-effectiveness of BSI vs SL-BPN from a US societal perspective.

METHODS

A Markov model simulated BSI and SL-BPN cohorts (clinically-stable adults) transiting through four mutually-exclusive health states for 12 months. Cohorts accumulated direct medical costs from drug acquisition/administration; treatment-diversion/abuse; newly-acquired hepatitis-C; emergency room, hospital, and rehabilitation services; and pediatric poisonings. Non-medical costs of criminality, lost wages/work-productivity, and out-of-pocket expenses were also included. Transition probabilities to a relapsed state were derived from the aforementioned trial. Other transition probabilities, costs, and health-state utilities were derived from observational studies and adjusted for trial characteristics. Outcomes included incremental cost per quality-adjusted-life-year (QALY) gained and incremental net-monetary-benefit (INMB). Uncertainty was assessed by univariate and probabilistic sensitivity analysis (PSA).

RESULTS

BSI was associated with lower total costs (-$4,386), more QALYs (+0.031), and favorable INMB at all willingness-to-pay (WTP) thresholds considered. Higher drug acquisition costs for BSI (+$6,492) were outpaced, primarily by reductions in emergency room/hospital utilization (-$8,040) and criminality (-$1,212). BSI was cost-effective in 89% of PSA model replicates, and had a significantly higher NMB at $50,000/QALY ($20,783 vs $15,007; p < .05).

CONCLUSIONS

BSI was preferred over SL-BPN from a health-economic perspective for treatment of OUD in clinically-stable adults. These findings should be interpreted carefully, due to some relationships having been modeled from inputs derived from multiple sources, and would benefit from comparison with outcomes from studies that employ administrative claims data or a naturalistic comparative design.

Opioid Addiction: Social Problems Associated and Implications of Both Current and Possible Future Treatments, including Polymeric Therapeutics for Giving Up the Habit of Opioid Consumption

BACKGROUND

Detoxification programmes seek to implement the most secure and compassionate ways of withdrawing from opiates so that the inevitable withdrawal symptoms and other complications are minimized. Once detoxification has been achieved, the next stage is to enable the patient to overcome his or her drug addiction by ensuring consumption is permanently and completely abandoned, only after which can the subject be regarded as fully recovered.

METHODS

A systematic search on the common databases of relevant papers published until 2016 inclusive.

RESULTS AND CONCLUSION

Our study of the available oral treatments for opioid dependence has revealed that no current treatment can actually claim to be fully effective. These treatments require daily oral administration and, consequently, regular visits to dispensaries, which in most cases results in a lack of patient compliance, which causes fluctuations in drug plasma levels. We then reviewed alternative treatments in the available scientific literature on polymeric sustained release formulations. Research has been done not only on release systems for detoxification but also on release systems for giving up the habit of taking opioids. These efforts have obtained the recent authorization of polymeric systems for use in patients that could help them to reduce their craving for drugs.

The North American opioid epidemic: current challenges and a call for treatment as prevention

There is a need for creative, public health-oriented solutions to the increasingly intractable problems associated with the North American opioid epidemic. This epidemic is a fundamentally continental problem, as routes of migration, drug demand, and drug exchange link the USA with Mexico and Canada. The challenges faced throughout North America include entrenched prescribing practices of opioid medications, high costs and low availability of medication-assisted treatment (MAT), and policy approaches that present substantial barriers to care.We advocate for the scale up of a low-threshold treatment model for MAT that incorporates the best practices in addiction treatment. Such a model would remove barriers to care through widespread treatment availability and affordability and also a policy of decriminalization. Given that MAT reduces the frequency of drug injecting among opioid injectors, this treatment model should also be guided by an understanding of the socially communicable nature of injection drug use, such that increasing MAT availability may also prevent the spread of injecting practices to individuals at risk of transitions from non-injection to injection drug use. To that end, the "Treatment as Prevention" model employed to respond to the individual- and population-level risks for HIV/AIDS prevention could be adapted to efforts to halt the North American opioid epidemic.

Probuphine® (buprenorphine implant): a promising candidate in opioid dependence

Opioid dependence leads to physical dependence and addiction which finally results in profound medical, psychological and social dysfunction. One of the useful medications for opioid dependence is buprenorphine, the partial opioid agonist, which is used alone or in combination with naloxone. However, buprenorphine is the victim of its own success due to its illicit use and accidental poisoning in children. Also, buprenorphine typically requires daily self-administration and its effectiveness heavily depends on patient adherence. So, poor treatment adherence results in ineffective treatment manifesting as craving and withdrawal symptoms. Short-term use of buprenorphine in opioid dependence is also often followed by relapse. Buprenorphine when used sublingually often results in inadequate or fluctuating blood concentrations and poorer treatment retention compared with methadone. All of these led to the development of Probuphine®, a polymeric matrix composed of ethylene vinyl acetate and buprenorphine in the form of implants, that are implanted subdermally in office practice and deliver the active drug over 6 months. Buprenorphine release from such implant is fairly consistent, avoiding plasma peaks and troughs, and the implant is also reported to be safe. In this review article, we have highlighted these aspects of treatment of opioid addiction, stressing on the pharmacology of buprenorphine and Probuphine®, and relevant clinical trials addressing the efficacy and safety of Probuphine®. This sustained-release implantable formulation of buprenorphine has the potential to be a suitable alternative to daily or alternate day sublingual buprenorphine which can thereby eliminate the need for daily supervision, minimizing fluctuations in plasma concentrations, and allowing these patients to reduce clinic or pharmacy visits.

Prescription opioid abuse in prison settings: A systematic review of prevalence, practice and treatment responses

BACKGROUND

To systematically review the quantitative and qualitative evidence base pertaining to the prevalence, practice of, and treatment response to the diversion of prescribed opiates in the prison setting.

METHODS

Medline, Embase, CINAHL, PsycINFO, Google Scholar, ASSIA and Science Direct databases were searched for papers from 1995 to the present relevant to the abuse of prescribed opiate medication. Identified journals and their reference lists were hand searched for other relevant articles. Of the abstracts identified as relevant, full text papers were retrieved and critiqued against the inclusion criteria for the review.

RESULTS

Three hundred and fifty-five abstracts were identified, leading to 42 full-text articles being retrieved. Of those, 10 papers were included in the review. Significant differences in abuse behaviours between different countries were reported. However, a key theme emerged from the data regarding a culture of nasal administration of prescribed sublingual buprenorphine within some prisons due to both reduced prevalence of injection within prison and reduced supplies of illicit drugs within prison. The buprenorphine/naloxone preparation appears to be less amenable to abuse. The review highlighted a paucity of empirical research pertaining to both prevalence of the phenomenon and treatment responses.

CLINICAL AND RESEARCH IMPLICATIONS

Healthcare providers within prisons need to prescribe opioids in the least abuseable preparation since the risk of abuse is significant, despite widespread processes of supervised dispensing. Prescription medication abuse is not limited to opioids and the predominant drug of abuse in an individual prison can rapidly change according to availability.

Implantable and transdermal polymeric drug delivery technologies for the treatment of central nervous system disorders

The complexity of the brain and the membranous blood-brain barrier (BBB) has proved to be a significant limitation to the systemic delivery of pharmaceuticals to the brain rendering them sub-therapeutic and ineffective in the treatment of neurological diseases. Apart from this, lack of innovation in product development to counteract the problem is also a major contributing factor to a poor therapeutic outcome. Various innovative strategies show potential in treating some of the neurological disorders; however, drug delivery remains the most popular. To attain therapeutic drug levels in the central nervous system, large, intolerable systemic doses are generally administered. The major factors responsible for the success maintenance therapy of neurological diseases included controlled and sustained release of neurotherapeutics, reduced frequency of administration, higher bioavailability, and patient compliances. Conventional oral or injectable formulations cannot satisfy all the requirements in many circumstances. This article reviews the therapeutic implantable polymeric and transdermal devices employed in an attempt to effectively achieve therapeutic quantities of drug across the BBB over a prolonged period, to improve patient disease prognosis.

Comparative prices of diverted buprenorphine/naloxone and buprenorphine in a UK prison setting: a cross-sectional survey of drug using prisoners

BACKGROUND

There is evidence regarding the abuse potential of buprenorphine in prison settings. There is also emerging evidence from community settings that buprenorphine/naloxone is less amenable to abuse than the single preparation buprenorphine hydrochloride as evidenced by cost-differentials of diverted medication. This study sought to explore cost-differentials within a prison setting of diverted buprenorphine/naloxone medication relative to either single preparation buprenorphine hydrochloride or methadone.

METHODS

Cross-sectional survey in one remand prison.

RESULTS

A total of 85 prisoners participated in the survey. Prisoners estimated buprenorphine to have a significantly (p<0.001) higher cost than buprenorphine/naloxone both inside and outside of prison. This finding was supported when the analysis was restricted to both the prisoners with a longer-term experience of taking opioid substitution drugs during their current prison stay and those with a longer-term experience prior to reception.

CONCLUSIONS

Consideration should be given to the recommendation that buprenorphine/naloxone medication is the prescribed buprenorphine preparation of choice for clinicians offering opiate substitution therapy to prisoners, pending developments of buprenorphine preparations that have less abuse potential than sublingual preparations.

Buprenorphine in the treatment of opioid addiction: opportunities, challenges and strategies

INTRODUCTION

Buprenorphine follows the success of methadone as another milestone in the history of treatment for opioid addiction. Buprenorphine can be used in an office-based setting where it is clearly effective, highly accepted by patients and has a favorable safety profile and less abuse potential. However, the adoption of buprenorphine treatment has been slow in the USA.

AREAS COVERED

This article first reviews the history of medication-assisted opioid addiction treatment and the current epidemic opioid addiction, followed by a review of the efficacy, pharmacology and clinical prescription of buprenorphine in office-based care. We then explore the possible barriers in using buprenorphine and the ways to overcome these barriers, including new formulations, educational programs and policy regulations that strike a balance between accessibility and reducing diversion.

EXPERT OPINION

Buprenorphine can align addiction treatment with treatments for other chronic medical illnesses. However, preventing diversion will require graduate and continuing medical education and integrated care models for delivery of buprenorphine to those in need.

Buprenorphine implant for opioid addiction

SUMMARY The buprenorphine implant (Probuphine™, Titan Pharmaceuticals, CA, USA) is a recently developed long-acting formulation of buprenorphine, which is a partial opioid agonist that is widely used in the marketed, sublingual, daily-dose form for managing opioid addiction. The new formulation uses a novel delivery system consisting of subcutaneously implanted solid matrix 'rods' made from a mixture of ethylene vinyl acetate and buprenorphine. The buprenorphine implant was developed to ensure medication compliance, eliminate misuse and abuse from diversion of sublingual buprenorphine, and increase therapeutic benefit of the medication. The implant is not a 'new' drug, but an innovative means of delivering a medication proven effective for treating opioid addiction. The implant has not yet been approved by the US FDA. The information in this review has been gleaned from research reports, documentation in the literature, and from the author's experience treating opioid-dependent patients, and involvement in clinical research examining sublingual buprenorphine and the buprenorphine implant.

Utilizing buprenorphine-naloxone to treat illicit and prescription-opioid dependence

OBJECTIVES

To review current evidence on buprenorphine-naloxone (bup/nx) for the treatment of opioid-use disorders, with a focus on strategies for clinical management and office-based patient care.

QUALITY OF EVIDENCE

Medline and the Cochrane Database of Systematic Reviews were searched. Consensus reports, guidelines published, and other authoritative sources were also included in this review. Apart from expert guidelines, data included in this review constitute level 1 evidence.

FINDINGS

Bup/nx is a partial μ-opioid agonist combined with the opioid antagonist naloxone in a 4:1 ratio. It has a lower abuse potential, carries less stigma, and allows for more flexibility than methadone. Bup/nx is indicated for both inpatient and ambulatory medically assisted withdrawal (acute detoxification) and long-term substitution treatment (maintenance) of patients who have a mild-to-moderate physical dependence. A stepwise long-term substitution treatment with regular monitoring and follow-up assessment is usually preferred, as it has better outcomes in reducing illicit opioid use, minimizing concomitant risks such as human immunodeficiency virus and hepatitis C transmission, retaining patients in treatment and improving global functioning.

CONCLUSION

Bup/nx is safe and effective for opioid detoxification and substitution treatment. Its unique pharmaceutical properties make it particularly suitable for office-based maintenance treatment of opioid-use disorder.

Multiple mechanisms underlying the long duration of action of thienorphine, a novel partial opioid agonist for the treatment of addiction

AIMS

It is considered that a long-acting therapy would be advantageous in the treatment of addiction. In a search for novel buprenorphine analogues, thienorphine was demonstrated to be an extremely long-acting orally active partial opioid agonist. This study explored the mechanisms underlying the long-lasting effects of thienorphine.

METHODS

The binding kinetics of [(3) H]thienorphine were measured in membrane preparations expressing cloned rat opioid receptors. Flow cytometric analysis was used to determine the effect of thienorphine on the surface opioid receptor number. The long-lasting effects of thienorphine were also confirmed at the tissue level and in vivo.

RESULTS

At 37°C, [(3) H]thienorphine showed rapid association with μ- and κ-opioid receptors, while its dissociation was sluggish and biphasic (K-1 = 0.21 min(-1) , K-2 = 0.0078 min(-1) for the μ-receptor; K-1 = 0.17 min(-1) , K-2 = 0.0042 min(-1) for the κ-receptor). Treatment with thienorphine for 24, 48, and 72 h downregulated surface μ-receptor in a dose- and time-dependent manner. The inhibitory effect of thienorphine on guinea pig ileum persisted for more than 120 min after prolonged washing. In vivo, thienorphine exhibited significant antagonism of morphine-induced antinociception for more than 7 days.

CONCLUSIONS

These results indicate that multiple factors, including persistent receptor occupation and enhanced receptor downregulation, may contribute to the long-lasting effects of thienorphine that would be beneficial for its application in addiction treatment.

Long-acting Preparations in Substance Abuse Management: A Review and Update

Many pharmacological approaches have been used in managing substance use disorders. Conventional pharmacological agents have relatively short durations of action which make them vulnerable to non-adherence and relapse to substance use disorder. To overcome this problem, long-acting preparations have been developed with the aim of reducing the frequency of use and hence improving adherence. This review takes a broad overview of the long-acting preparations available for the management of substance use disorders. The pharmacology, advantages and disadvantages of these preparations are discussed. Many of these preparations hold promise for improving patient outcomes.

Effect of buprenorphine dose on treatment outcome

The goal of this meta-analysis is to provide evidence based information about proper dosing for buprenorphine maintenance treatment to improve treatment outcome. To be selected for the review and inclusion in the meta-analysis, articles had to be randomized, controlled, or double-blind clinical trials, with buprenorphine as the study drug; the length of buprenorphine maintenance treatment had to be 3 weeks or longer; doses of buprenorphine had to be clearly stated; outcome measures had to include retention rates in buprenorphine treatment; outcome measures had to include illicit opioid use based on analytical determination of drugs of abuse in urine samples as outcome variables; and outcome measures had to include illicit cocaine use based on analytical determination of drugs of abuse in urine samples as outcome variables. Twenty-nine articles were excluded because they did not meet the inclusion criteria. The authors present the results of 21 articles that met inclusion criteria. The higher buprenorphine dose (16-32 mg per day) predicted better retention in treatment compared with the lower dose (less than 16 mg per day) (P = .009, R(2) adjusted = 0.40), and the positive urine drug screens for opiates predicted dropping out of treatment (P = .019, R(2) Adjusted = 0.40). Retention in treatment predicted less illicit opioid use (P = .033, R(2) Adjusted = 0.36), and the positive urine drug screens for cocaine predicted more illicit opioid use (P = .021, R(2) Adjusted = 0.36). Strong evidence exists based on 21 randomized clinical trials that the higher buprenorphine dose may improve retention in buprenorphine maintenance treatment.

Treatment outcome for flexible dosing buprenorphine maintenance treatment

BACKGROUND AND OBJECTIVES

Achieving the best treatment outcome with the least cost should be the goal for buprenorphine office-based treatment.

METHODS

We conducted an observational retrospective chart review to compare the treatment outcome for patients (n = 56) receiving high dose of buprenorphine (above 16 mg daily) and patients (n = 21) receiving moderate doses (8-16 mg daily).

RESULTS

The percentages of the first four urine drug screens (UDS) positive for opiates were significantly higher for the high-dose group than for the moderate-dose group (F = 7.93, df = 7, p < .0001). However, the percentages of the most recent four UDS positive for opiates were not statistically significant (F = .62, df = 7, p = .74). The difference in the percentages of the first and last UDS for the high-dose group showed significant reduction from admission to most recently but there was no significant difference for the moderate-dose group (t = 3.1, df = 105, p = .002 for the high-dose group and t = 1.1, df = 40, p = .27 for the moderate-dose group).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Using flexible buprenorphine dosing schedule with the option of titrating the dose up to 32 mg daily may offer better treatment outcome for patients who would not respond to the lower dose range.

The association between outpatient buprenorphine detoxification duration and clinical treatment outcomes: a review

BACKGROUND

The association between buprenorphine taper duration and treatment outcomes is not well understood. This review evaluated whether duration of outpatient buprenorphine taper is significantly associated with treatment outcomes.

METHODS

Studies that were published in peer-reviewed journals, administered buprenorphine as an outpatient taper to opioid-dependent participants, and provided data on at least one of three primary treatment outcome measures (opioid abstinence, retention, peak withdrawal severity) were reviewed. Primary treatment outcomes were evaluated as a function of taper duration using hierarchical linear regressions with pre-taper maintenance duration as a cofactor.

RESULTS

Twenty-eight studies were reviewed. Taper duration significantly predicted percent of opioid-negative samples provided during treatment, however pre-taper maintenance period predicted percent participants abstinent on the final day of treatment. High rates of relapse were reported. No significant association between taper duration and retention in treatment or peak withdrawal severity was observed.

CONCLUSION

The data reviewed here suggest taper duration is associated with opioid abstinence achieved during detoxification but not with other markers of treatment outcome. The reviewed studies varied widely on several parameters (e.g., frequency of urinalysis testing, provision of ancillary medications) that may influence treatment outcome and thus could have interfered with the ability to identify relationships between taper duration and outcomes. Future studies evaluating opioid detoxification should utilize rigorous experimental methods and report a wider range of outcome measures in order to help advance our understanding of the association between taper duration and treatment outcomes.

Buprenorphine and buprenorphine/naloxone diversion, misuse, and illicit use: an international review

The diversion, misuse, and non-medically supervised use of buprenorphine and buprenorphine/naloxone by opioid users are reviewed. Buprenorphine and buprenorphine/naloxone are used globally as opioid analgesics and in the treatment of opioid dependency. Diversion of buprenorphine and buprenorphine/naloxone represents a complex medical and social issue, and has been widely documented in various geographical regions throughout the world. We first discuss the clinical properties of buprenorphine and its abuse potential. Second, we discuss its diversion and illicit use on an international level, as well as motivations for those activities. Third, we examine the medical risks and benefits of buprenorphine's non-medically supervised use and misuse. These risks and benefits include the effect of buprenorphine's use on HIV risk and the risk of its concomitant use with other medications and drugs of abuse. Finally, we discuss the implications of diversion, misuse, and non-medically supervised use (including potential measures to address issues of diversion); and potential areas for further research.

Heroin anticraving medications: a systematic review

BACKGROUND

Heroin craving is a trigger for relapse and dropping out of treatment. Methadone has been the standard medication for the management of heroin craving.

OBJECTIVES

We explored the medication options other than methadone which may have heroin anticraving properties.

METHODS

To be selected for the review, articles had to include outcome measures of the effect of the studied medication on subjective and/or objective opiate craving and be of the following two types: (1) randomized, controlled, and/or double-blind clinical trials (RCTs) examining the relationship between the studied medication and heroin craving; (2) nonrandomized and observational studies (NRSs) examining the relationship between the studied medication and heroin craving. Thirty-three articles were initially included in the review. Twenty-one were excluded because they did not meet the inclusion criteria. We present the results of 12 articles that met all the inclusion criteria.

RESULTS

Some new medications have been under investigation and seem promising for the treatment of opiate craving. Buprenorphine is the second most studied medication after methadone for its effect on opiate craving. At doses above 8 mg daily, it seems very promising and practical for managing opiate craving in patients receiving long-term opioid maintenance treatment.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

In doses higher than 8 mg daily, buprenorphine is an appropriate treatment for opiate craving. More research with rigorous methodology is needed to study the effect of buprenorphine on heroin craving. Also more studies are needed to directly compare buprenorphine and methadone with regard to their effects on heroin craving.