Abuse potential of intranasal buprenorphine versus buprenorphine/naloxone in buprenorphine-maintained heroin users

Buprenorphine for the Treatment of Military-related PTSD With Treatment-resistant Depression and Unexpected Benefit for Chronic Pain: Case Report

The prevalence of treatment-resistant depression within global and military populations highlights the need for novel treatment approaches beyond monoamine neurotransmitter modulators. Buprenorphine (BUP), a semi-synthetic partial opioid agonist, is approved for the treatment of opioid use disorder and has shown promise in treating both depression and chronic pain. This case report discusses the use of transdermal BUP in treating a 36 year-old man with treatment-resistant depression with prominent anhedonia, military-related posttraumatic stress disorder, and chronic pain because of barosinusitis. Significant reductions in anxious and depressive symptoms, including in anhedonia, were observed with lasting effects. An unexpected finding was the discontinuation of prescribed hydromorphone for pain, suggesting the potential unique benefit of BUP in treating chronic pain and treatment resistant depression comorbidities. These findings implicate the diverse beneficial potential of BUP in psychiatric treatments for military populations.

Reconsidering the usefulness of long-term high-dose buprenorphine

Buprenorphine has been successfully used for decades in the treatment of opioid use disorder, yet there are complexities to its use that warrant attention to maximize its utility. While the package insert of the combination product buprenorphine\naloxone continues to recommend a maximum dose of 16 mg daily for maintenance, the emergence of fentanyl and synthetic analogs in the current drug supply may be limiting the effectiveness of this standard dose. Many practitioners have embraced and appropriately implemented novel practices to mitigate the sequelae of our current crisis. It has become common clinical practice to stabilize patients with 24 - 32 mg of buprenorphine daily at treatment initiation. Many of these patients, however, are maintained on these high doses (>16 mg/d) indefinitely, even after prolonged stability. Although this may be a necessary strategy in the short term, there is little evidence to support its safety and efficacy, and these high doses may be exposing patients to more complications and side effects than standard doses. Commonly known side effects of buprenorphine that are likely dose-related include hyperhidrosis, sedation, decreased libido, constipation, and hypogonadism. There are also complications related to the active metabolite of buprenorphine (norbuprenorphine) which is a full agonist at the mu opioid receptor and does not have a ceiling on respiratory suppression. Such side effects can lead to medical morbidity as well as decreased medication adherence, and we, therefore, recommend that after a period of stabilization, practitioners consider a trial of decreasing the dose of buprenorphine toward standard dose recommendations. Some patients' path of recovery may never reach this stabilization phase (i.e., several months of adherence to medications, opioid abstinence, and other clinical indicators of stability). Side effects of buprenorphine may not have much salience when patients are struggling for survival and safety, but for those who are fortunate enough to advance in their recovery, the side effects become more problematic and can limit quality of life and adherence.

The Naloxone Component of Buprenorphine/Naloxone: Discouraging Misuse, but at What Cost?

Because opioid overdose deaths in the United States continue to rise, it is critical to increase patient access to buprenorphine, which treats opioid use disorder and reduces mortality. An underrecognized barrier to buprenorphine treatment (both for maintenance and treatment of acute withdrawal) is limited access to buprenorphine monoproduct. In the United States, buprenorphine is primarily prescribed as a combination product also containing naloxone, added to reduce the potential for misuse. Because naloxone has relatively low sublingual bioavailability compared with buprenorphine, adverse effects are generally considered mild and rare. The authors' clinical experience, however, suggests that adverse effects may be less benign than generally accepted and can have negative effects for the patient, the provider-patient relationship, and the health care system as a whole. The insistence on prescribing combination product can foster stigma and mistrust, creating barriers to care and increased risk of overdose and death.

Association Between Buprenorphine Treatment Gaps, Opioid Overdose, and Health Care Spending in US Medicare Beneficiaries With Opioid Use Disorder

Importance

Nonadherence to buprenorphine may increase patient risk of opioid overdose and increase health care spending. Quantifying the impacts of nonadherence can help inform clinician practice and policy.

Objective

To estimate the association between buprenorphine treatment gaps, opioid overdose, and health care spending.

Design, Setting, and Participants

This longitudinal case-control study compared patient opioid overdose and health care spending in buprenorphine-treated months with treatment gap months. Individuals who were US Medicare fee-for-service beneficiaries diagnosed with opioid use disorder who received at least 1 two-week period of continuous buprenorphine treatment between 2010 and 2017 were included. Analysis took place between January 2010 and December 2017.

Interventions

A gap in buprenorphine treatment in a month lasting more than 15 consecutive days.

Main Outcomes and Measures

Opioid overdose and total, medical, and drug spending (combined patient out-of-pocket and Medicare spending).

Results

Of 34 505 Medicare beneficiaries (17 927 [520%] male; 16 578 [48.1%] female; mean [SD] age, 49.5 [12.7] years; 168 [0.5%] Asian; 2949 [8.5%] Black; 2089 [6.0%] Hispanic; 266 [0.8%] Native American; 28 525 [82.7%] White; 508 [1.5%] other race), 11 524 beneficiaries (33.4%) experienced 1 or more buprenorphine treatment gaps. Treatment gap beneficiaries, compared with nontreatment gap beneficiaries, were more likely to be younger, be male, have a disability, and be Medicaid dual-eligible while less likely to be White, close to a buprenorphine prescriber, and treated with buprenorphine monotherapy (ie, buprenorphine hydrochloride). Beneficiaries were 2.89 (95% CI, 2.20-3.79) times more likely to experience an opioid overdose during buprenorphine treatment gap months compared with treated months. During treatment gap months, spending was $196.41 (95% CI, $110.53-$282.30) more than in treated months. Patients who continued to take buprenorphine dosages of greater than 8 mg/d and 16 mg/d were 2.61 and 2.84 times more likely to overdose in a treatment gap month, respectively, while patients taking buprenorphine dosages of 8 mg/d or less were 3.62 times more likely to overdose in a treatment gap month (maintenance of >16 mg/d: hazard ratio (HR), 2.64 [95% CI, 1.80-3.87]; maintenance of >8 mg/d: HR, 2.84 [95% CI, 2.13-3.78]; maintenance of ≤8 mg/d: HR, 3.62 [95% CI, 1.54-8.50]). Buprenorphine monotherapy was associated with greater risk of overdose and higher spending during treatment gaps months than buprenorphine/naloxone.

Conclusions and Relevance

Medicare patients treated with buprenorphine between 2010 and 2017 had a lower associated opioid overdose risk and spending during treatment months than treatment gap months.

Pain, negative affective states and opioid-based analgesics: Safer pain therapies to dampen addiction

Across centuries and civilizations opioids have been used to relieve pain. In our modern societies, opioid-based analgesics remain one of the most efficient treatments for acute pain. However, the long-term use of opioids can lead to the development of analgesic tolerance, opioid-induced hyperalgesia, opioid use disorders, and overdose, which can ultimately produce respiratory depressant effects with fatal consequences. In addition to the nociceptive sensory component of pain, negative affective states arising from persistent pain represent a risk factor for developing an opioid use disorder. Several studies have indicated that the increase in prescribed opioid analgesics since the 1990s represents the root of our current opioid epidemic. In this review, we will present our current knowledge on the endogenous opioid system within the pain neuroaxis and the plastic changes occurring in this system that may underlie the occurrence of pain-induced negative affect leading to misuse and abuse of opioid medications. Dissecting the allostatic neuronal changes occurring during pain is the most promising avenue to uncover novel targets for the development of safer pain medications. We will discuss this along with current and potential approaches to treat pain-induced negative affective states that lead to drug misuse. Moreover, this chapter will provide a discussion on potential avenues to reduce the abuse potential of new analgesic drugs and highlight a basis for future research and drug development based on recent advances in this field.

Opioid system modulation with buprenorphine/samidorphan combination for major depressive disorder: two randomized controlled studies

The endogenous opioid system is thought to play an important role in the regulation of mood. Buprenorphine/samidorphan (BUP/SAM) combination is an investigational opioid system modulator for adjunctive treatment of major depressive disorder (MDD). To confirm results from early studies, we report the efficacy and safety of BUP/SAM as adjunctive treatment in patients with MDD and an inadequate response to antidepressant therapy (ADT) in FORWARD-4 and FORWARD-5: two phase 3, randomized, double-blind, placebo-controlled studies that utilized the same sequential parallel-comparison design. Efficacy was measured using the Montgomery-Åsberg Depression Rating Scale (MADRS). FORWARD-5 achieved the primary endpoint and demonstrated that adjunctive BUP/SAM 2 mg/2 mg was superior to placebo (average difference change from baseline to week 3 through end of treatment [EOT] in MADRS-6 and -10 versus placebo: -1.5, P = 0.018; -1.9, P = 0.026, respectively). FORWARD-4 did not achieve the primary endpoint (change from baseline in MADRS-10 at week 5 versus placebo: -1.8, P = 0.109), although separate analyses showed significant treatment differences at other timepoints using traditional, regulatory-accepted endpoints such as reduction in MADRS-10 at EOT. The pooled analysis of the two studies demonstrated consistently greater reduction in MADRS-10 scores from baseline for BUP/SAM 2 mg/2 mg versus placebo at multiple timepoints including EOT and average change from baseline to week 3 through EOT (-1.8, P = 0.010; -1.8, P = 0.004, respectively). The overall effect size (Hedges' g) in the pooled analyses for MADRS-10 change from baseline to EOT was 0.22. Overall, BUP/SAM was generally well tolerated, with most adverse events (AEs) being mild or moderate in severity. The most common AEs, occurring in ≥5% of patients in the BUP/SAM 2 mg/2 mg treatment group, which was more frequently than the placebo group, included nausea, constipation, dizziness, vomiting, somnolence, fatigue, and sedation. There was minimal evidence of abuse, and no evidence of dependence or opioid withdrawal by AEs or objective measures. This report describes adjunctive BUP/SAM 2 mg/2 mg combination, a therapy with a novel opioidergic mechanism of action, as a potential new treatment option for patients with MDD who have an inadequate response to currently available ADT.

Results from a long-term open-label extension study of adjunctive buprenorphine/samidorphan combination in patients with major depressive disorder

Buprenorphine/samidorphan (BUP/SAM; ALKS 5461) is an investigational opioid system modulator for the adjunctive treatment of patients with major depressive disorder (MDD), who did not respond adequately to prior antidepressant therapy (ADT). FORWARD-2, an open-label extension study, assessed long-term safety and tolerability of adjunctive BUP/SAM treatment in these patients. Patients from four short-term trials and de novo patients were enrolled; all had confirmed MDD and a current major depressive episode lasting 2-24 months. Patients were treated with an established ADT for ≥8 weeks before receiving sublingual, adjunctive BUP/SAM 2 mg/2 mg for up to 52 weeks. Safety (primary objective) was assessed via adverse events (AEs), the Columbia-Suicide Severity Rating Scale, and the Clinical Opiate Withdrawal Scale (COWS). Exploratory evaluation of efficacy was done using the Montgomery-Åsberg Depression Rating Scale (MADRS). Of 1485 patients, 50% completed the study and 11% discontinued due to AEs. AEs of nausea, headache, constipation, dizziness, and somnolence, each occurred in ≥10% of patients. There was no evidence of increased suicidal ideation or behavior. Euphoria-related AEs were uncommon (1.2%). Following abrupt BUP/SAM discontinuation, "drug withdrawal" AEs were infrequent (0.4%), and the incidence of COWS categorical worsening after abrupt drug discontinuation was low (6.5%). Improvements in mean MADRS scores were maintained until study end, suggesting durability of antidepressant effect in patients continuing treatment. BUP/SAM was generally well tolerated, with a low risk of abuse and an AE profile consistent with those seen in placebo-controlled studies. Withdrawal reports were uncommon and of limited clinical impact.

Behavioral Effects of Opioid Full and Partial Agonists During Chronic Buprenorphine Treatment

Buprenorphine, a partial agonist at the μ-opioid receptor, is commonly prescribed for the management of opioid addiction. Notwithstanding buprenorphine's clinical popularity, the relationship between its effectiveness in attenuating relapse-related behavior and its opioid efficacy is poorly understood. Furthermore, changes in the antinociceptive potency or effectiveness of opioid drugs that might occur during buprenorphine treatment have not been characterized. Here, we address these questions by assessing the ability of daily buprenorphine treatment to protect against the reinstatement of drug-seeking behavior by six opioids differing in efficacy (methadone, heroin, oxycodone, buprenorphine, butorphanol, nalbuphine) and, in separate experiments, by determining how such treatment may modify their antinociceptive effects. In one set of experiments, squirrel monkeys were trained to respond under concurrent schedules (choice) of food or intravenous oxycodone presentations. The priming strength of different opioids during sessions in which saline, rather than oxycodone, was available for intravenous self-administration was determined before and during chronic buprenorphine treatment (0.1 or 0.32 mg/kg per day). In other subjects, antinociceptive effects of the different opioids were assessed using cumulative dosing procedures in a modified warm-water tail withdrawal procedure before and during buprenorphine treatment. Results show that, notwithstanding some tolerance, full agonists retain high efficacy in producing priming and antinociceptive effects. In contrast, both the priming strength and antinociceptive effectiveness of partial agonists were decreased. These results suggest that the utility of buprenorphine in the management of opioid addiction, and how it alters the analgesic effects of opioids, can vary depending on the efficacy of the abused or prescribed opioid. SIGNIFICANCE STATEMENT: Our findings indicate that the pharmacological efficacy of abused opioids may predict the ability of buprenorphine to attenuate their relapse-related priming and analgesia-related antinociceptive effects. This information can help inform physicians as to the effectiveness and limitations of buprenorphine as a pharmacotherapy for opioid addiction.

Non-prescribed use of methadone and buprenorphine prior to opioid substitution treatment: lifetime prevalence, motives, and drug sources among people with opioid dependence in five Swedish cities

BACKGROUND

Opioid substitution treatment (OST) with methadone or buprenorphine is the most effective means of treating opioid dependence. If these substances are used by people who are not undergoing OST, they can however carry serious risks. This article examines the lifetime prevalence, motives, and drug sources for such use, as well as geographical differences in these variables.

METHODS

Structured interviews were conducted with 411 patients from 11 OST clinics in five Swedish cities. The researchers carried out 280 interviews on-site, while 131 interviews were conducted by specially trained patients through privileged access interviewing. Data were analyzed by frequency and average calculations, cross-tabulations, and χ2 tests.

RESULTS

The lifetime prevalence of non-prescribed use was 87.8% for methadone, 80.5% for buprenorphine, and 50.6% for buprenorphine/naloxone. Pseudo-therapeutic motives-avoiding withdrawal symptoms, staying clean from heroin, detoxification, or taking care of one's own OST-were commonly cited as driving the use, while using the drugs for euphoric purposes was a less common motive. Most respondents had bought or received the substances from patients in OST, but dealers were also a significant source of non-prescribed methadone and buprenorphine. Geographical differences of use, motives, and sources suggest that prescription practices in OST have a great impact on which substances are used outside of the treatment.

CONCLUSIONS

Experiences of non-prescribed use of methadone and buprenorphine are extremely common among those in OST in southern Sweden. As the use is typically driven by pseudo-therapeutic motives, increased access to OST might decrease the illicit demand for these substances. Buprenorphine/naloxone has a lower abuse potential than buprenorphine and should therefore be prioritized as the prescribed drug. Supervised dosage and other control measures are important provisions in the prevention of drug diversion and non-prescribed use among people not undergoing OST.

Pain Therapy Guided by Purpose and Perspective in Light of the Opioid Epidemic

Prescription opioid misuse is an ongoing and escalating epidemic. Although these pharmacological agents are highly effective analgesics prescribed for different types of pain, opioids also induce euphoria, leading to increasing diversion and misuse. Opioid use and related mortalities have developed in spite of initial claims that OxyContin, one of the first opioids prescribed in the USA, was not addictive in the presence of pain. These claims allayed the fears of clinicians and contributed to an increase in the number of prescriptions, quantity of drugs manufactured, and the unforeseen diversion of these drugs for non-medical uses. Understanding the history of opioid drug development, the widespread marketing campaign for opioids, the immense financial incentive behind the treatment of pain, and vulnerable socioeconomic and physical demographics for opioid misuse give perspective on the current epidemic as an American-born problem that has expanded to global significance. In light of the current worldwide opioid epidemic, it is imperative that novel opioids are developed to treat pain without inducing the euphoria that fosters physical dependence and addiction. We describe insights from preclinical findings on the properties of opioid drugs that offer insights into improving abuse-deterrent formulations. One finding is that the ability of some agonists to activate one pathway over another, or agonist bias, can predict whether several novel opioid compounds bear promise in treating pain without causing reward among other off-target effects. In addition, we outline how the pharmacokinetic profile of each opioid contributes to their potential for misuse and discuss the emergence of mixed agonists as a promising pipeline of opioid-based analgesics. These insights from preclinical findings can be used to more effectively identify opioids that treat pain without causing physical dependence and subsequent opioid abuse.

Changes in Withdrawal and Craving Scores in Participants Undergoing Opioid Detoxification Utilizing Ibogaine

Opioid use disorder (OUD) is currently an epidemic in the United States (US) and ibogaine is reported to have the ability to interrupt opioid addiction by simultaneously mitigating withdrawal and craving symptoms. This study examined opioid withdrawal and drug craving scores in 50 participants with OUD undergoing a week-long detoxification treatment protocol with ibogaine. The Addiction Severity Index (ASI) was used for baseline characterization of participants' OUD. Clinical Opioid Withdrawal Scale (COWS), Subjective Opioid Withdrawal Scale (SOWS), and Brief Substance Craving Scale (BSCS) scores were collected at 48 and 24 hours prior to ibogaine administration, as well as 24 and 48 hours after ibogaine administration. At 48 hours following ibogaine administration, withdrawal and craving scores were significantly lowered in comparison to baseline: 78% of patients did not exhibit objective clinical signs of opioid withdrawal, 79% reported minimal cravings for opioids, and 68% reported subjective withdrawal symptoms in the mild range. Ibogaine appears to facilitate opioid detoxification by reducing opioid withdrawal and craving in participants with OUD. These results warrant further research using rigorous controlled trials.

Decline in Buprenorphine/Naloxone Prescriptions in a State Medicaid Population Following Formulary Conversion from Suboxone to Bunavail

INTRODUCTION

A large, statewide, fee-for-service Medicaid plan recently (October 2015) executed a complete switch from sublingual buprenorphine-naloxone [(SLBN), Suboxone^®] to buccal buprenorphine-naloxone [(BBN), Bunavail^®] on its preferred drug formulary. This complete formulary switch provided an opportunity to assess dynamic changes in prescribing patterns, patient/physician acceptance, and indices of potential misuse/diversion.

METHODS

For the period January 1, 2015 through December 31, 2016, two datasets were analyzed: prescriptions and associated costs for buprenorphine-naloxone (BN) products and urine toxicology test results for patients in the Medicaid plan. The dataset comprised 1370 unique providers ordering 643,225 prescriptions for opioid addiction therapy. Patient and order volumes, and the rate of monthly positive laboratory values for opioid molecules and cocaine were reviewed. A targeted survey of physicians treating opioid-dependent patients with state Medicaid plan coverage was also conducted.

RESULTS

Upon plan conversion to BBN, there was a rapid increase in monthly BBN prescriptions mirrored by a rapid decrease in SLBN prescriptions. Peak in BBN prescriptions (2633 in November 2015) was approximately 60% lower than peak in SLBN prescriptions (6531 in July 2015). An unexpected finding was a 68% reduction of the overall BN market, indicating that many BN prescriptions were abandoned. The reduction was associated with quarterly cost savings to the Medicaid plan of approximately $3.5 million. Toxicology results indicated a reduction in drug positivity (defined as positivity for cocaine and/or any opioids except buprenorphine and methadone) from 13-16% in 2015 to less than 10% in 2016. Heroin positivity decreased from approximately 9% in December 2015 to an average of less than 1% during the last quarter of 2016, while positivity for norbuprenorphine, the major metabolite of buprenorphine, showed a marked increase in 2016 vs 2015. Among physicians who responded to the targeted survey most rated BBN as more difficult to abuse or misuse than SLBN.

CONCLUSION

The rapid reduction in the overall BN market following a complete formulary switch from SLBN to BBN was associated with quarterly savings of $3.5 million for the state Medicaid plan. Toxicology data suggest that this cost saving was realized in the context of improved physician and patient adherence to treatment protocols. The changing market dynamics can potentially be explained by a number of contributory factors, including a reduction of diversion and illicit distribution of BN following formulary conversion. These results are considered hypothesis-generating and future research should systematically compare the propensity for diversion and abuse of BN products using various epidemiological tracking tools.

FUNDING

BioDelivery Sciences International, Inc.

A Stable Heroin Analogue That Can Serve as a Vaccine Hapten to Induce Antibodies That Block the Effects of Heroin and Its Metabolites in Rodents and That Cross-React Immunologically with Related Drugs of Abuse

An improved synthesis of a haptenic heroin surrogate 1 (6-AmHap) is reported. The intermediate needed for the preparation of 1 was described in the route in the synthesis of 2 (DiAmHap). A scalable procedure was developed to install the C-3 amido group. Using the Boc protectng group in 18 allowed preparation of 1 in an overall yield of 53% from 4 and eliminated the necessity of preparing the diamide 13. Hapten 1 was conjugated to tetanus toxoid and mixed with liposomes containing monophosphoryl lipid A as an adjuvant. The 1 vaccine induced high anti-1 IgG levels that reduced heroin-induced antinociception and locomotive behavioral changes following repeated subcutaneous and intravenous heroin challenges in mice and rats. Vaccinated mice had reduced heroin-induced hyperlocomotion following a 50 mg/kg heroin challenge. The 1 vaccine-induced antibodies bound to heroin and other abused opioids, including hydrocodone, oxycodone, hydromorphone, oxymorphone, and codeine.

Abuse liability of intravenous buprenorphine vs. buprenorphine/naloxone: Importance of absolute naloxone amount

BACKGROUND

This study sought to determine the relative importance of a range of Bup/Nx doses compared to Bup alone in producing subjective and reinforcing effects.

METHODS

Heroin-using volunteers (n=13) were transitioned onto daily oral hydromorphone (40mg). Laboratory sessions assessed the reinforcing and subjective effects of intravenous (IV) doses of Bup (1.51, 2.16, 6.15, and 8.64mg) and Bup/Nx (1.51/0.44, 2.16/0.61, 6.15/1.71, and 8.64/2.44mg). Placebo (Pbo), heroin (25mg) and Nx (0.3mg) were tested as neutral, positive, and negative controls, respectively.

RESULTS

IV Bup alone was self-administered substantially less than IV heroin, though the two largest doses of Bup produced positive subjective effects, drug "Liking" (0-100mm), which were comparable to heroin (mean difference: Heroin vs Bup 6.15mg: -3.4mm, Heroin vs Bup 8.64mg: -11.3mm). All indicators of abuse potential seen with IV Bup alone were substantially decreased with the addition of Nx. All Bup/Nx combinations produced ratings of aversive effects, "Bad", which were comparable to, or greater than IV, Nx. On three of the four measures of aversive effects, the largest difference is seen with the 8.64 vs 8.64/2.44 condition.

CONCLUSIONS

This study further demonstrates the ability of the Bup/Nx combination to deter IV use. Although none of the Bup/Nx combinations showed indications of abuse potential, formulations with larger absolute Nx, may be less abusable as they precipitate a greater degree of withdrawal.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

The Abuse Potential of Prescription Opioids in Humans-Closing in on the First Century of Research

While opioids are very effective analgesics for treating acute pain, humans have struggled with opiate addiction for millenia. An opium abuse epidemic in the early 1900's led the US government to develop a systematic research infrastructure and scientific plan to produce new compounds with analgesic properties but without abuse liability. This review describes the techniques that were developed for testing in the human laboratory, including empirically derived outcome measures and required elements for human abuse potential assessment. The evaluation and characterization of semi-synthetic and synthetic opioids, including full mu opioid agonists, partial agonists and mixed agonist-antagonists, are described across several decades of research. Finally, the prescription opioid epidemic beginning in the 1990's in the US led to a resurgence in abuse potential evaluations, and the application of these methods to the study of novel abuse-deterrent formulations is discussed.

Buprenorphine Prescribing: To Expand or Not to Expand

As a result of the prescription opioid epidemic in the United States, there has been an increasing need for effective treatment interventions, both pharmacological and nonpharmacological. Buprenorphine has emerged as a critical component of the treatment of opioid use disorder, yet its adoption has not been without some concerns. This article first reviews the pharmacology, clinical use, and US legislative action related to buprenorphine, followed by a discussion of the misuse and diversion of buprenorphine in the United States as well as internationally. We then explore the impact of buprenorphine abuse as well as discussing strategies for its reduction, including changes in policy, prescription and pharmacy monitoring, and continuing medical education for guiding and improving clinical practice.

Intranasal buprenorphine alone and in combination with naloxone: Abuse liability and reinforcing efficacy in physically dependent opioid abusers

BACKGROUND

Buprenorphine can be abused by the intranasal route. This study sought to examine the relative abuse liability and reinforcing efficacy of intranasal buprenorphine compared to intranasal buprenorphine/naloxone in opioid-dependent individuals.

METHODS

Eleven healthy male and female volunteers physically dependent on short-acting opioids resided as inpatients during participation in this double blind, within subject, placebo-controlled study. Participants were maintained on oxycodone (30 mg/q.i.d., p.o.) throughout the 6-week study. Eight pairs of experimental sessions were conducted at ≥48 h intervals to examine the pharmacodynamic profile (Sample) and reinforcing efficacy (Self-administration the following day) of intranasal placebo, oxycodone (60 mg), buprenorphine (2, 8 & 16 mg) and buprenorphine/naloxone (2/0.5, 8/2 & 16/4 mg). Subjective, observer-rated and physiological measures were collected to assess the magnitude of opioid agonist and antagonist effects. A progressive ratio self-administration procedure assessed choices for drug versus money.

RESULTS

All active doses produced opioid agonist-like effects (e.g., increased ratings of "liking," and miosis) compared to placebo. The effects of buprenorphine and buprenorphine/naloxone were not reliably dose-dependent. Intranasal buprenorphine/naloxone elicited modest and transient opioid withdrawal-like effects in the first hour post-drug administration, while simultaneously blunting or blocking the early onset of agonist effects seen with buprenorphine alone. All active doses of buprenorphine were self-administered more than placebo, but buprenorphine/naloxone doses were not.

CONCLUSIONS

These data confirm that intranasal buprenorphine/naloxone has deterrent properties related to transient withdrawal effects that likely decrease its desirability for misuse compared to buprenorphine in opioid-dependent individuals maintained on short-acting opioids.

Searching for evidence of genetic mediation of opioid withdrawal by opioid receptor gene polymorphisms

BACKGROUND

Previous research has identified many genetic polymorphisms that appear to mediate the effects of opioid drugs. However, the relationship between genetic polymorphisms and the severity of opioid withdrawal has not yet been characterized.

METHODS

Data were collected from 48 daily heroin users who previously completed a standardized abstinence-induced or naloxone-precipitated withdrawal procedure to assess opioid dependence. The total withdrawal severity score (based on the COWS) from this procedure was correlated with genotype information for variants of OPRM1 (rs1799971; rs6848893), OPRD1 (rs10753331; rs2234918; rs581111; rs678849; rs1042114), and OPRK1 (rs6473797; rs963549). Genotype and other participant variables (age, race, sex, duration of drug use, concomitant drug use, route of opioid use) were used as predictors.

RESULTS

Of these variables, those individually correlated with a p < .2 were entered into a multivariate regression in order to identify the most predictive model. Three polymorphisms were significantly associated with severity of abstinence-induced withdrawal (n = 19) in the bivariate analysis (R): OPRM1 rs6848893 (.45), OPRD1 rs10753331 (.03), and rs678849 (.08), but only the OPRM1 rs6848893 was retained in the multivariate model (p < .001). For participants who underwent naloxone-precipitated withdrawal (n = 29) only OPRK1 rs6473797 (-.23) was significant in the bivariate analysis, though not retained in the final model.

CONCLUSIONS

These data provide evidence for genetic modulation of opioid withdrawal severity, and suggest there may be qualitative differences between withdrawal resulting from abstinence and antagonist-precipitated withdrawal.

SCIENTIFIC SIGNIFICANCE

This study demonstrates the importance and feasibility of incorporating genetic information into clinical addiction research.

Need and utility of a polyethylene glycol marker to ensure against urine falsification among heroin users

BACKGROUND

Deceptive methods of falsifying urine samples are of concern for anyone who relies on accurate urine toxicology results. A novel method to combat these efforts utilizes polyethylene glycol (PEG) markers administered orally prior to providing a urine sample. By using various PEG combinations to create a tracer capsule of unique composition, each urine sample can be matched to that individual. The goal of this study was to determine the effectiveness of using the PEG marker system among active heroin users screening for research studies.

METHODS

Upon each screening visit, participants (N=55) were randomized to provide an unobserved urine sample, or the PEG tracer procedure was used. LCMS analysis was used to distinguish the PEG combinations, and allowed us to provide a unique qualitative analysis of patterns of drug use (N=168, total urine specimens).

RESULTS

The unique composition of the tracer capsules was accurately detected in 83.5% of the urine specimens. Analyses of inconsistencies implicated a number of possible attempts at fraudulence (11.4%) and investigator/lab error (5.1%). Among this sample, the concurrent use of multiple classes of psychoactive drugs was more common than not, though concomitant drug use was often underreported.

CONCLUSION

Urine drug testing should be the minimum standard for obtaining information about drug use as self-report was unreliable even in a situation where there were no perceived adverse consequences for full disclosure. In cases where there are significant pressures for individuals to falsify these data, more protective collection methods such as the PEG marker system should be considered.

New developments in the management of opioid dependence: focus on sublingual buprenorphine-naloxone

Opioid maintenance therapy is a well-established first-line treatment approach in opioid dependence. Buprenorphine, a partial opioid agonist, has been found by numerous studies to be an effective and safe medication in the treatment of opioid dependence. At present, buprenorphine is available as a monodrug or in a fixed 4:1 ratio combination with naloxone. A diminished risk of diversion and abuse for the buprenorphine-naloxone combination is likely but not firmly established. Conventional formulations are given sublingually to avoid the hepatic first-pass effect. A novel film tablet is available only in the US and Australia. Other novel, sustained-release formulations (implant, depot) are currently being developed and tested. Recent studies, including a Cochrane meta-analysis, suggest that the retention with buprenorphine is lower than for methadone, but that buprenorphine may be associated with less drug use. Higher doses of buprenorphine are associated with better retention rates. Buprenorphine has a ceiling effect at the opioid receptor with regard to respiratory depression, and may cause fewer fatal intoxications than methadone. Possible antidepressant effects of buprenorphine and its use in comorbid psychiatric patients has not been studied in much detail. Clinical implications are discussed.