Management of Opioid Addiction With Opioid Substitution Treatments: Beyond Methadone and Buprenorphine

Oxytocin Reduces Noradrenergic-Induced Opioid-Like Withdrawal Symptoms in Individuals on Opioid Agonist Therapy

Background

Intranasal administration of the neuropeptide oxytocin has been explored as a potential therapeutic agent for substance use disorder including opioid use disorder (OUD).

Methods

This phase 1, crossover, randomized, double-blind, placebo-controlled trial tested the safety, tolerability, and efficacy of intranasal oxytocin (80 IU) twice a day for 7 days in participants (N = 20) with OUD who were taking an opioid agonist therapy. In the laboratory, participants underwent opioid cue exposure paired with noradrenergic activation produced by yohimbine (32.4 mg) or placebo. Assessments included, 1) subjective response: craving, withdrawal, anxiety, and stress; 2) biomedical markers: hypothalamic-pituitary-adrenal axis response (cortisol) and noradrenergic activation (α-amylase); and 3) safety measures: hemodynamics and adverse event evaluation. Generalized linear model with model-based estimator in the covariance matrix was used, with medication (oxytocin/placebo) and noradrenergic activation (yohimbine/placebo) as within-subject factors.

Results

Oxytocin significantly reduced opioid-like withdrawal, anxiety symptoms, and cortisol levels elicited by cue exposure under noradrenergic activation produced by yohimbine. This effect was specific because oxytocin did not reduce craving, hemodynamics, or α-amylase levels increased by yohimbine administration. A single dose of yohimbine elicited the noradrenergic stimulation, and 7-day oxytocin administration was safe and well tolerated among individuals diagnosed with OUD and taking opioid agonist therapy.

Conclusions

The findings of this study suggest that oxytocin alleviates opioid-like withdrawal symptoms and anxiety by modulating the hypothalamic-pituitary-adrenal axis.

Placebo Effects: Neurological Mechanisms Inducing Physiological, Organic, and Belief Responses-A Prospective Analysis

The placebo effect can induce physiological or clinical neurological and organic responses despite the recipient receiving no active ingredients; these responses are based instead on the recipient's perceptions. Placebo effects come from the rostral anterior cingulate cortex, pontine nucleus, and cerebellum of the brain; this information provides a better understanding of placebo effects and can also help us understand the mechanism of the modulation of neurotransmitters from the use of psychedelic substances, activity of selective serotonin reuptake inhibitors, the process of transcranial magnetic stimulation, and deep brain stimulation, as well as aid in developing novel therapies, challenging the validity of controlled clinical trials (RCTs) that the regulatory agencies now appreciate. Education about how placebo effects bring in social, political, and religious beliefs and whether these can be modulated may help reduce global confrontations.

Structure-Based Engineering of Monoclonal Antibodies for Improved Binding to Counteract the Effects of Fentanyl and Carfentanil

The opioid overdose epidemic is a growing and evolving public health crisis fueled by the widespread presence of fentanyl and fentanyl analogues (F/FAs) in both street mixtures and counterfeit pills. To expand current treatment options, drug-targeting monoclonal antibodies (mAbs) offer a viable therapeutic for both pre- and postexposure clinical scenarios. This study reports the isolation, in vitro characterization, and in vivo efficacy of two murine mAb families targeting fentanyl, carfentanil, or both. Because humanization of the mAbs by CDR grafting negatively impacted affinity for both fentanyl and carfentanil, crystal structures of mAbs in complex with fentanyl or carfentanil were analyzed to identify key residues involved in ligand binding in murine versus humanized structures, and site-directed mutagenesis was used to verify their functional importance. The structural analysis identified a framework residue, Tyr36, present in the murine germline sequence of two mAbs, which was critical for binding to fentanyl and carfentanil. These studies emphasize the importance of structural considerations in mAb engineering to optimize mAbs targeting small molecules including opioids and other drugs of public health interest.

Ketamine and hydroxynorketamine as novel pharmacotherapies for the treatment of Opioid-Use Disorders

Opioid use disorder (OUD) has reached epidemic proportions, with many countries facing high opioid use and related fatalities. Although currently-prescribed medications for OUD (MOUD) are considered life-saving, they inadequately address negative affect and cognitive impairment, resulting in high relapse rates to non-medical opioid use, even years after drug cessation (protracted abstinence). Evidence supports the notion that ketamine, an anesthetic and rapid-acting antidepressant drug, holds promise as a candidate for OUD treatment, including the management of acute withdrawal somatic symptoms, negative affect during protracted opioid abstinence and prevention of re-taking non-medical opioids. In this review, we comprehensively discuss preclinical and clinical research evaluating ketamine and its metabolites as potential novel therapeutic strategies for treating OUDs. We further examine evidence supporting the relevance of the molecular targets of ketamine and its metabolites in relation to their potential effects and therapeutic outcomes in OUDs. Overall, existing evidence demonstrates that ketamine and its metabolites can effectively modulate pathophysiological processes affected in OUD, suggesting their promising therapeutic role in the treatment of OUD and the prevention of return to opioid use during abstinence.

Caregivers' Attitudes Toward Treatment Length for Persons in Swedish Opioid Agonist Treatment. A Qualitative Interview Study

Although opioid agonist treatment (OAT) has several beneficial effects, the issue of optimal treatment length remains unresolved. It is plausible that caregivers' attitudes toward treatment length are of importance to whether, how and when tapering off will take place. In this study, we investigated caregivers' attitudes toward treatment length by interviewing 15 caregivers from a variety of professions working in seven OAT treatment programs in Sweden. Data were analyzed using applied thematic analysis. The participants were generally hesitant concerning the idea of tapering off. Few of them had experiences of patients tapering off successfully. Many of them never brought up the subject unless the patient did so her-/himself. Only younger, socially stable patients were perceived to be suitable for tapering off. Participants also expressed a need among staff for education and ethical discussions on treatment length. A person-centered focus may be promoted by recurrently discussing treatment goals and by co-operating with patients to map the recovery capital of those interested in tapering. To further support caregivers in developing person-centered care, more knowledge of opioid use disorder and professional and interprofessional discussions of caregivers' own attitudes and beliefs are paramount.

Single cell transcriptomics reveals distinct transcriptional responses to oxycodone and buprenorphine by iPSC-derived brain organoids from patients with opioid use disorder

The opioid epidemic represents a national crisis. Oxycodone is one of the most prescribed opioid medications in the United States, whereas buprenorphine is currently the most prescribed medication for opioid use disorder (OUD) pharmacotherapy. Given the extensive use of prescription opioids and the global opioid epidemic, it is essential to understand how opioids modulate brain cell type function at the single-cell level. We performed single nucleus RNA-seq (snRNA-seq) using iPSC-derived forebrain organoids from three male OUD subjects in response to oxycodone, buprenorphine, or vehicle for seven days. We utilized the snRNA-seq data to identify differentially expressed genes following drug treatment using the Seurat integrative analysis pipeline. We utilized iPSC-derived forebrain organoids and single-cell sequencing technology as an unbiased tool to study cell-type-specific and drug-specific transcriptional responses. After quality control filtering, we analyzed 25787 cells and identified sixteen clusters using unsupervised clustering analysis. Our results reveal distinct transcriptional responses to oxycodone and buprenorphine by iPSC-derived brain organoids from patients with OUD. Specifically, buprenorphine displayed a significant influence on transcription regulation in glial cells. However, oxycodone induced type I interferon signaling in many cell types, including neural cells in brain organoids. Finally, we demonstrate that oxycodone, but not buprenorphine activated STAT1 and induced the type I interferon signaling in patients with OUD. These data suggest that elevation of STAT1 expression associated with OUD might play a role in transcriptional regulation in response to oxycodone. In summary, our results provide novel mechanistic insight into drug action at single-cell resolution.

The Therapeutic Potential of Cannabidiol in Revolutionising Opioid Use Disorder Management

Opioid use disorder (OUD) is a significant cause of morbidity and mortality worldwide and is linked to a complex interplay of biopsychosocial factors as well as the increasing overprescription and availability of opioid medications. Current OUD management relies on the controlled provision of opioid medications, such as methadone or buprenorphine, known as opioid replacement therapy. There is variable evidence regarding the long-term efficacy of these medications in improving the management of OUD, thereby necessitating an exploration into innovative approaches to complement, or even take the place of, existing treatment paradigms. Cannabidiol (CBD), a non-psychoactive compound derived from the cannabis plant, has garnered attention for its diverse pharmacological properties, including anti-inflammatory, analgesic, and anxiolytic effects. Preliminary studies suggest that CBD may target opioid withdrawal pathways that make CBD a potential therapeutic option for OUD. This narrative review synthesises current literature surrounding OUD and offers a nuanced review of the current and future role of CBD in managing this condition. In doing so, we highlight the potential avenues to explore with respect to CBD research for the guidance and development of further research opportunities, framework and policy development, and clinical considerations before medicinal CBD can be integrated into evidence-based clinical guidelines.

Sublingual/Buccal buprenorphine and dental problems: a pharmacovigilance study

BACKGROUND

The association between dental problems and sublingual/buccal buprenorphine is unclear. We conducted an analysis of dental adverse drug reactions reported with sublingual/buccal buprenorphine in VigiBase®, the pharmacovigilance database of the World Health Organization.

RESEARCH DESIGN AND METHODS

We performed disproportionality analyses to compare the reporting rates of dental problems with sublingual/buccal buprenorphine, compared to other buprenorphine formulations and methadone. Significant signals were considered if the lower boundary of the 95% confidence interval of the Reporting Odds Ratio (ROR) was > 1; cases were ≥ 3 and p-value <0.05. We conducted sensitivity analyses by calculating the ROR according to the reporter's qualification and the reporting continent (United States of America and Europe).

RESULTS

We included 30,769 reports with all buprenorphine forms. We found 20 cases of dental problems with sublingual/buccal buprenorphine. Sublingual/buccal buprenorphine was associated with an overreporting of dental problems compared to other buprenorphine formulations (ROR = 15.10; 95% CI [7.50-30.39]; p < 0.005) and compared to methadone (ROR = 6.02; 95% CI [3.21-11.30]; p < 0.005). Overreporting of dental problems was consistent in sensitivity analyses, except in Europe compared with other buprenorphine formulations and with methadone.

CONCLUSIONS

Sublingual/buccal buprenorphine might increase the risk of reporting dental problems. However, these results do not modify the benefits of sublingual/buccal buprenorphine in the treatment of opioid use disorders.

Control of the diastereoselectivity at C(20) in the formation of C(21)-fluorinated thevinols

A method is reported to control the stereoselectivity at C(20) in the syntheses of 20-R-21,21,21-trifluorothevinols (12), the opioid ligands incorporating fluorine atoms within the pharmacophore associated with the surroundings of the C(20) carbon atom. The C(20)-alcohols 12 can be prepared either by reaction of 21,21,21-trifluorothevinone (9) with RM (R = alkyl; M = Li, MgX) or by reaction of thevinone (2) and related non-fluorinated ketones with CF₃SiMe₃. In general, alcohols 12 were formed as mixtures of the C(20)-epimers, with the major epimers of the alcohols obtained from the aforementioned reactions exploiting RLi vs. CF₃SiMe₃ with opposite absolute configurations at C(20). Some individual C(20)-epimers of the fluorinated alcohols 12 were isolated from the reaction mixtures in pure form by trivial crystallization. The reactions of the ketones with RMgX (R ≠ Me) and RLi (R = tertiary or secondary alkyl) resulted in the reduction of the carbonyl function to produce the secondary alcohols 11a,b rather than the tertiary alcohols 12. The additives of the salts were found to affect the composition of the products in the reactions of 9 with alkyl organomagnesium and organolithium reagents.

Structures of drug-specific monoclonal antibodies bound to opioids and nicotine reveal a common mode of binding

Opioid-related fatal overdoses have reached epidemic proportions. Because existing treatments for opioid use disorders offer limited long-term protection, accelerating the development of newer approaches is critical. Monoclonal antibodies (mAbs) are an emerging treatment strategy that targets and sequesters selected opioids in the bloodstream, reducing drug distribution across the blood-brain barrier, thus preventing or reversing opioid toxicity. We previously identified a series of murine mAbs with high affinity and selectivity for oxycodone, morphine, fentanyl, and nicotine. To determine their binding mechanism, we used X-ray crystallography to solve the structures of mAbs bound to their respective targets, to 2.2 Å resolution or higher. Structural analysis showed a critical convergent hydrogen bonding mode that is dependent on a glutamic acid residue in the mAbs' heavy chain and a tertiary amine of the ligand. Characterizing drug-mAb complexes represents a significant step toward rational antibody engineering and future manufacturing activities to support clinical evaluation.

Effect of TRV130 and methadone on fentanyl-vs.-food choice and somatic withdrawal signs in opioid-dependent and post-opioid-dependent rats

The high efficacy mu-opioid receptor (MOR) agonist methadone is an effective opioid use disorder (OUD) medication used exclusively in opioid-dependent patients. However, methadone has undesirable effects that limit its clinical efficacy. Intermediate efficacy MOR agonists may treat OUD with fewer undesirable effects. We compared the effects of methadone with the intermediate efficacy MOR agonist TRV130 (oliceridine) on fentanyl-vs.-food choice and somatic withdrawal signs in opioid-dependent and post-opioid-dependent rats. Male rats (n = 20) were trained under a fentanyl-vs.-food choice procedure. Rats were then provided extended fentanyl (3.2 µg/kg/infusion) access (6 p.m.-6 a.m.) for 10 days to produce opioid dependence/withdrawal. Rats were treated with vehicle (n = 7), TRV130 (3.2 mg/kg; n = 8), or methadone (3.2 mg/kg; n = 5) three times per day after each extended-access session (8:30 a.m., 11 a.m., 1:30 p.m.). Withdrawal sign scoring (1:55 p.m.) and choice tests (2-4 p.m.) were conducted daily. Vehicle, TRV130, and methadone effects on fentanyl choice were redetermined in post-opioid-dependent rats. Vehicle-, TRV130-, and methadone-treated rats had similar fentanyl intakes during extended access. Vehicle-treated rats exhibited increased withdrawal signs and decreased bodyweights. Both methadone and TRV130 decreased these withdrawal signs. TRV130 was less effective than methadone to decrease fentanyl choice and increase food choice in opioid-dependent rats. Neither methadone nor TRV130 decreased fentanyl choice in post-opioid-dependent rats. Results suggest that higher MOR activation is required to reduce fentanyl choice than withdrawal signs in fentanyl-dependent rats. Additionally, given that TRV130 did not precipitate withdrawal in opioid-dependent rats, intermediate efficacy MOR agonists like TRV130 may facilitate the transition of patients with OUD from methadone to lower efficacy treatments like buprenorphine.

Patients’ Perspectives on Coming Off Opioid Agonist Treatment: A Qualitative Study

Aims:

Opioid agonist treatment (OAT) programs are life-saving, as they reduce opioid use, overdoses, and criminal activities. Disadvantages reported with long-term OAT include side effects of the medication, especially on cognitive ability and sexual function, which may discourage potential participants. Many of those who participate in OAT have a desire to come off treatment. The aims of this study were to explore patients’ thoughts about coming off OAT and to investigate their perceptions of what support they would need in order to realize a planned withdrawal from OAT.

Methods:

A qualitative interview study with semi-structured interviews, using applied thematic analysis. Persons with experiences of participating in OAT were invited from Swedish programs and a private Facebook community.

Results:

Fifteen persons, with a mean of 9.6 (±6.4) years of treatment experience, were included. The participants underlined the need for a patient-centered focus within the treatment. They wanted to be regarded as capable of deciding if, when, and how a planned ending was to take place. They also called for staff to be supportive in making such decisions. Participants recommended staff to be sensitive to the needs of the specific patient and to have strategies for coming off OAT that could be adjusted for the single person.

Conclusions:

OAT programs need to be continually updated and adapted to the persons who can benefit from them. Applying a person-centered, holistic perspective would enhance the quality of the treatment by emanating from individual goals. Regulatory guidelines need to take into account research on patient experiences and perspectives on coming off.

Epigenetic Regulation of Circadian Clocks and Its Involvement in Drug Addiction

Based on studies describing an increased prevalence of addictive behaviours in several rare sleep disorders and shift workers, a relationship between circadian rhythms and addiction has been hinted for more than a decade. Although circadian rhythm alterations and molecular mechanisms associated with neuropsychiatric conditions are an area of active investigation, success is limited so far, and further investigations are required. Thus, even though compelling evidence connects the circadian clock to addictive behaviour and vice-versa, yet the functional mechanism behind this interaction remains largely unknown. At the molecular level, multiple mechanisms have been proposed to link the circadian timing system to addiction. The molecular mechanism of the circadian clock consists of a transcriptional/translational feedback system, with several regulatory loops, that are also intricately regulated at the epigenetic level. Interestingly, the epigenetic landscape shows profound changes in the addictive brain, with significant alterations in histone modification, DNA methylation, and small regulatory RNAs. The combination of these two observations raises the possibility that epigenetic regulation is a common plot linking the circadian clocks with addiction, though very little evidence has been reported to date. This review provides an elaborate overview of the circadian system and its involvement in addiction, and we hypothesise a possible connection at the epigenetic level that could further link them. Therefore, we think this review may further improve our understanding of the etiology or/and pathology of psychiatric disorders related to drug addiction.

Exploring the use of cannabis as a substitute for prescription drugs in a convenience sample

BACKGROUND

The use of cannabis as medicine (CaM) both prescribed and non-prescribed has increased markedly in the last decade, mirrored in a global shift in cannabis policy towards a more permissive stance. There is some evidence that cannabis functions as a substitute for prescription drugs, particularly opioids; however, more knowledge is needed on the motives of substitution users, their patterns of use, and perceived effects of substitution use.

AIMS

To explore who substitutes prescription drugs with cannabis, the type of prescription drugs substituted and the type of cannabis used, and the impact that substitution with cannabis has on prescription drug use as well as the motives for substitution in terms of experienced effects and side effects.

METHODS

A self-selected convenience sample was recruited through social media, public media, and patient organizations to take part in an anonymous online survey. Inclusion criteria were 18 years or older and use of cannabis (prescribed or non-prescribed) with a medical purpose.

RESULTS

The final sample included 2.841 respondents of which the majority (91%) used non-prescribed cannabis, and more than half (54.6%) had used CaM with the purpose of replacing a prescribed drug. Compared to non-substitution users, substitution users were more likely to be women and to use CaM in the treatment of chronic pain and other somatic conditions. Pain medication (67.2%), antidepressants (24.5%), and arthritis medication (20.7%) were the most common types of drugs replaced with CaM. Among substitution users, 38.1% reported termination of prescription drug use, and 45.9% a substantial decrease in prescription drug use. The most frequent type of cannabis used as a substitute was CBD-oil (65.2%), followed by 'hash, pot or skunk' (36.6%). More than half (65.8%) found CaM much more effective compared to prescription drugs, and 85.5% that the side effects associated with prescription drug use were much worse compared to use of CaM.

CONCLUSION

CaM is frequently used as a substitute for prescription drugs, particularly opioids. More research is needed on the long-term consequences of use of CaM, including the impact from low and high THC cannabis products on specific somatic and mental health conditions.

Monitoring Prenatal Exposure to Buprenorphine and Methadone

PURPOSE

Buprenorphine and methadone are international gold standards for managing opioid use disorders. Although they are efficacious in treating opioid dependence, buprenorphine and methadone present risks, especially during pregnancy, causing neonatal abstinence syndrome and adverse obstetrical outcomes. Buprenorphine and methadone are also abused during pregnancy, and identifying their use is important to limit unprescribed prenatal exposure. Previous studies have suggested that concentrations of buprenorphine, but not methadone markers in unconventional matrices may predict child outcomes, although currently only limited data exist. We reviewed the literature on concentrations of buprenorphine, methadone, and their metabolites in unconventional matrices to improve data interpretation.

METHODS

A literature search was conducted using scientific databases (PubMed, Scopus, Web of Science, and reports from international institutions) to review published articles on buprenorphine and methadone monitoring during pregnancy.

RESULTS

Buprenorphine and methadone and their metabolites were quantified in the meconium, umbilical cord, placenta, and maternal and neonatal hair. Methadone concentrations in the meconium and hair were typically higher than those in other matrices, although the concentrations in the placenta and umbilical cord were more suitable for predicting neonatal outcomes. Buprenorphine concentrations were lower and required sensitive instrumentation, as measuring buprenorphine glucuronidated metabolites is critical to predict neonatal outcomes.

CONCLUSIONS

Unconventional matrices are good alternatives to conventional ones for monitoring drug exposure during pregnancy. However, data are currently scarce on buprenorphine and methadone during pregnancy to accurately interpret their concentrations. Clinical studies should be conducted with larger cohorts, considering confounding factors such as illicit drug co-exposure.

Medications Development for Treatment of Opioid Use Disorder

This review describes methods for preclinical evaluation of candidate medications to treat opioid use disorder (OUD). The review is founded on the propositions that (1) drug self-administration procedures provide the most direct method for assessment of medication effectiveness, (2) procedures that assess choice between opioid and nondrug reinforcers are especially useful, and (3) states of opioid dependence and withdrawal profoundly influence both opioid reinforcement and effects of candidate medications. Effects of opioid medications and vaccines on opioid choice in nondependent and opioid-dependent subjects are reviewed. Various nonopioid medications have also been examined, but none yet have been identified that safely and reliably reduce opioid choice. Future research will focus on (1) strategies for increasing safety and/or effectiveness of opioid medications (e.g., G-protein-biased μ-opioid agonists), and (2) continued development of nonopioid medications (e.g., clonidine) that might serve as adjunctive agents to current opioid medications.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV. Graphical Abstract Blood-brain barrier and the neurovascular unit. With HIV and opiate co-exposure (represented below the dotted line), there is breakdown of tight junction proteins and increased leakage of paracellular compounds into the brain. Despite this, opiate exposure selectively increases the expression of some efflux transporters, thereby restricting brain penetration of specific drugs.

Non-Opioid Treatments for Opioid Use Disorder: Rationales and Data to Date

Opioid use disorder (OUD) represents a major public health problem that affects millions of people in the USA and worldwide. The relapsing and recurring aspect of OUD, driven by lasting neurobiological adaptations at different reward centres in the brain, represents a major obstacle towards successful long-term remission from opioid use. Currently, three drugs that modulate the function of the opioidergic receptors, methadone, buprenorphine and naltrexone have been approved by the US Food and Drug Administration (FDA) to treat OUD. In this review, we discuss the limitations and challenges associated with the current maintenance and medication-assisted withdrawal strategies commonly used to treat OUD. We further explore the involvement of glutamatergic, endocannabinoid and orexin signaling systems in the development, maintenance and expression of addiction-like behaviours in animal models of opioid addiction, and as potential and novel targets to expand therapeutic options to treat OUD. Despite a growing preclinical literature highlighting the role of these potential targets in animal models of opioid addiction, clinical and translational studies for novel treatments of OUD remain limited and inconclusive. Further preclinical and clinical investigations are needed to expand the arsenal of primary treatment options and adjuncts to maximise efficacy and prevent relapse.

Oxidative Stress and Neuroinflammation as a Pivot in Drug Abuse. A Focus on the Therapeutic Potential of Antioxidant and Anti-Inflammatory Agents and Biomolecules

Drug abuse is a major global health and economic problem. However, there are no pharmacological treatments to effectively reduce the compulsive use of most drugs of abuse. Despite exerting different mechanisms of action, all drugs of abuse promote the activation of the brain reward system, with lasting neurobiological consequences that potentiate subsequent consumption. Recent evidence shows that the brain displays marked oxidative stress and neuroinflammation following chronic drug consumption. Brain oxidative stress and neuroinflammation disrupt glutamate homeostasis by impairing synaptic and extra-synaptic glutamate transport, reducing GLT-1, and system X_c⁻ activities respectively, which increases glutamatergic neurotransmission. This effect consolidates the relapse-promoting effect of drug-related cues, thus sustaining drug craving and subsequent drug consumption. Recently, promising results as experimental treatments to reduce drug consumption and relapse have been shown by (i) antioxidant and anti-inflammatory synthetic molecules whose effects reach the brain; (ii) natural biomolecules secreted by mesenchymal stem cells that excel in antioxidant and anti-inflammatory properties, delivered via non-invasive intranasal administration to animal models of drug abuse and (iii) potent anti-inflammatory microRNAs and anti-miRNAs which target the microglia and reduce neuroinflammation and drug craving. In this review, we address the neurobiological consequences of brain oxidative stress and neuroinflammation that follow the chronic consumption of most drugs of abuse, and the current and potential therapeutic effects of antioxidants and anti-inflammatory agents and biomolecules to reduce these drug-induced alterations and to prevent relapse.

Too much or too little opioids to patients receiving opioid agonist therapy in Norway (2013-2017): a prospective cohort study

BACKGROUND

Dispensations of opioid analgesics to patients on opioid agonist therapy (OAT) may increase the risk of overdoses. The current study's objectives are to investigate the dispensation rates and mean daily doses of dispensed opioid analgesics among patients who received OAT opioids in Norway during 2013-2017 and evaluate whether discontinuing OAT opioids affects the dispensed dose of opioid analgesics.

METHODS

Information on opioids was collected from the Norwegian Prescription Database. Dispensation rates were calculated by dividing the number of patients who were dispensed at least one opioid analgesic by the number of patients who were dispensed an OAT opioid. We calculated the mean daily dose of opioid analgesics in oral morphine equivalents. The OAT opioid dose was defined as a ratio between the dispensed doses divided by the mean recommended dose. We used logistic regression to estimate the association between the dispensation of an opioid analgesic, a dose of OAT opioids, having chronic pain, and being on palliative care.

RESULTS

A total of 10,371 patients were dispensed at least one OAT opioid during the study period. In 2017, 18% were dispensed an opioid analgesic with a mean daily dose of 29 mg of oral morphine equivalents. Being dispensed an opioid analgesic was associated with having chronic pain (adjusted odds ratio (aOR): 3.6, 95% confidence interval: 3.2-4.2), being on palliative care (aOR: 6.1, 4.7-7.9), and receiving an OAT opioid dose below half of the recommended OAT dose (aOR: 1.7, 1.4-2.0). Similar results were seen in 2013-2016. The discontinuation of OAT opioids could increase the dose of dispensed opioid analgesics.

CONCLUSION

Reducing the dispensation of opioid analgesics can be achieved by increasing the OAT opioid dose for patients on a low OAT dose, and by extending the period needed to taper off the OAT opioid dose at discontinuation.

Efficacy of multimodal analgesic treatment of severe traumatic acute pain in mice pretreated with chronic high dose of buprenorphine inducing mechanical allodynia

Managing severe acute nociceptive pain in buprenorphine-maintained individuals for opioid use disorder management is challenging owing to the high affinity and very slow dissociation of buprenorphine from μ-opioid receptors that hinders the use of full agonist opioid analgesics. In a translational approach, the aim of this study was to use an animal setting to investigate the effects of a chronic high dose of buprenorphine treatment on nociceptive thresholds before and after applying a severe acute nociceptive traumatic surgery stimulus and to screen postoperative pharmacological analgesic strategies. A chronic treatment of mice with a high dose of buprenorphine (BUP HD, 2 × 200 μg/kg/day; i.p.) revealed significant mechanical allodynia. One and two days after having discontinued buprenorphine administration and having induced a severe nociceptive acute pain by a closed tibial fracture, acute administration of morphine at a dose which has analgesic effects in absence of pretreatment (4.5 mg/kg; i.p.), was ineffective to reduce pain in the BUP HD group. However, mimicking multimodal analgesia strategy used in human postoperative context, the combination of morphine (administered at the same dose) with a NMDA receptor antagonist (ketamine) or an NSAID (ketoprofen) produced antinociceptive responses in these animals. The mouse model of closed tibial fracture could be useful to identify analgesic strategies of postoperative pain for patients with chronic exposure to opioids and suffering from hyperalgesia.

Overcoming Heroin Addiction without the Use of Pharmaceuticals: A Qualitative Interview Study

Although opioid maintenance treatment lowers mortality and has proven efficacy in reducing opioid use, it is not an option for every person with an opioid addiction. Studies of the experiences of those who have overcome their addiction without pharmaceuticals are rare, but vital to understanding the quitting process and how it can be facilitated. This study investigated what persons with a previous heroin addiction perceived as helpful when overcoming their addiction without the use of pharmaceuticals, and what they consider important for health services to consider. Eleven adults with former heroin addiction participated. Most described the leaving process as prolonged and including many attempts. Experiences such as being worn out and numb, life-threatening overdoses, personal losses or a growing feeling of missing important stages in life fueled the decision process. Envisioning a future without drugs was described as an important component. To maintain the decision to refrain from heroin use the possibility to gain a new social context was crucial. Results imply that health care professionals should be proactive by seizing the moment of opportunity for change (e.g., after an overdose), and should be empathetic and never give up on a person. Those concerned with care, welfare and other support or control systems in society must cooperate to offer more personalized support.

Overlap in the neural circuitry and molecular mechanisms underlying ketamine abuse and its use as an antidepressant

Ketamine, a dissociative anesthetic and psychedelic compound, has revolutionized the field of psychopharmacology by showing robust, and rapid-acting antidepressant activity in patients suffering from major depressive disorder (MDD), suicidal tendencies, and treatment-resistant depression (TRD). Ketamine's efficacy, however, is transient, and patients must return to the clinic for repeated treatment as they experience relapse. This is cause for concern because ketamine is known for its abuse liability, and repeated exposure to drugs of abuse often leads to drug abuse/dependence. Though the mechanism(s) underlying its antidepressant activity is an area of current intense research, both clinical and preclinical evidence shows that ketamine's effects are mediated, at least in part, by molecular adaptations resulting in long-lasting synaptic changes in mesolimbic brain regions known to regulate natural and drug reward. This review outlines our limited knowledge of ketamine's neurobiological and biochemical underpinnings mediating its antidepressant effects and correlates them to its abuse potential. Depression and addiction share overlapping neural circuitry and molecular mechanisms, and though speculative, repeated use of ketamine for the treatment of depression could lead to the development of substance use disorder/addiction, and thus should be tempered with caution. There is much that remains to be known about the long-term effects of ketamine, and our lack of understanding of neurobiological mechanisms underlying its antidepressant effects is a clear limiting factor that needs to be addressed systematically before using repeated ketamine in the treatment of depressed patients.

Neuropharmacological and Neurogenetic Correlates of Opioid Use Disorder (OUD) As a Function of Ethnicity: Relevance to Precision Addiction Medicine

BACKGROUND

Over 100 people die daily from opioid overdose and $78.5B per year is spent on treatment efforts, however, the real societal cost is multifold greater. Alternative strategies to eradicate/manage drug misuse and addiction need consideration. The perception of opioid addiction as a social/criminal problem has evolved to evidence-based considerations of them as clinical disorders with a genetic basis. We present evaluations of the genetics of addiction with ancestryspecific risk profiles for consideration.

OBJECTIVE

Studies of gene variants associated with predisposition to substance use disorders (SUDs) are monolithic, and exclude many ethnic groups, especially Hispanics and African Americans. We evaluate gene polymorphisms that impact brain reward and predispose individuals to opioid addictions, with a focus on the disparity of research which includes individuals of African and Hispanic descent.

METHODOLOGY

PubMed and Google Scholar were searched for: Opioid Use Disorder (OUD), Genome- wide association studies (GWAS); genetic variants; polymorphisms, restriction fragment length polymorphisms (RFLP); genomics, epigenetics, race, ethnic group, ethnicity, ancestry, Caucasian/ White, African American/Black, Hispanic, Asian, addictive behaviors, reward deficiency syndrome (RDS), mutation, insertion/deletion, and promotor region.

RESULTS

Many studies exclude non-White individuals. Studies that include diverse populations report ethnicity-specific frequencies of risk genes, with certain polymorphisms specifically associated with Caucasian and not African-American or Hispanic susceptibility to OUD or SUDs, and vice versa.

CONCLUSION

To adapt precision medicine-based addiction management in a blended society, we propose that ethnicity/ancestry-informed genetic variations must be analyzed to provide real precision- guided therapeutics with the intent to attenuate this uncontrollable fatal epidemic.

Evaluation of dynorphin and kappa-opioid receptor level in the human blood lymphocytes and plasma: Possible role as a biomarker in severe opioid use disorder

BACKGROUND

The dynorphin (DYN)/kappa opioid receptor (KOR) system plays an important role in the development of addiction, and dysregulation of this system could lead to abnormal activity in the reward pathway. It has been reported that the expression state of the neurotransmitters and their receptors in the brain is reflected in peripheral blood lymphocytes (PBLs).

METHODS

We have evaluated the PBLs and plasma samples of four groups: 1) subjects with severe opioid use disorder (SOD), 2) methadone-maintenance treated (MMT) individuals, 3) long-term abstinent subjects having former SOD, and 4) healthy control subjects (n = 20 in each group). The mRNA expression level of preprodynorphin (pPDYN) and KOR in PBLs has been evaluated by real-time PCR. Peptide expression of PDYN in PBLs has been studied by western blot, and DYN concentration in plasma has been measured by ELISA.

RESULTS

The relative expression level of the pPDYN mRNA and PDYN peptide in PBLs were significantly up-regulated in SOD, MMT, and abstinent groups compared to control subjects. No significant difference was found in the plasma DYN concentration between study groups. The expression level of the KOR mRNA in PBLs was significantly decreased in all three study groups compared to the control subjects.

CONCLUSION

the expression changes in the DYN/KOR system after chronic exposure to opioids, including methadone, seems to be stable and does not return to normal levels even after 12 months abstinence. These long-time and permanent changes in PBLs may serve as a biomarker and footprint of SOD development in the periphery.

Craving in Opioid Use Disorder: From Neurobiology to Clinical Practice

Opioid use disorder (OUD) is a major public health issue that has reached epidemic levels in some parts of the world. It is a chronic and complex neurobiological disease associated with frequent relapse to drug taking. Craving, defined as an overwhelmingly strong desire or need to use a drug, is a central component of OUD and other substance use disorders. In this review, we describe the neurobiological and neuroendocrine pathways that underpin craving in OUD and also focus on the importance of assessing and treating craving in clinical practice. Craving is strongly associated with patients returning to opioid misuse and is therefore an important treatment target to reduce the risk of relapse and improve patients' quality of life. Opioid agonist therapies (OAT), such as buprenorphine and methadone, can significantly reduce craving and relapse risk, and it is essential that patients are treated optimally with these therapies. There is also evidence to support the benefits of non-pharmacological approaches, such as cognitive behavioral therapy and mindfulness-based interventions, as supplementary treatments to opioid agonist therapies. However, despite the positive impact of these treatments on craving, many OUD patients continue to suffer with negative affect and dysphoria. There is a clear need for further studies to progress our understanding of the neurobiological basis of craving and addiction and to identify novel therapeutic strategies as well as to optimize the use of existing treatments to improve outcomes for the growing numbers of patients affected by OUD.