Opioid Addiction, Genetic Susceptibility, and Medical Treatments: A Review

Patients' requests and physicians' prescribing behavior. A systematic review

BACKGROUND

Patients' requests is a frequently cited factor in the literature affecting doctors' prescribing decisions. This systematic review aims to consolidate quantitative findings, shedding light on the relationship between patient requests and the actions taken by general practitioners. A broader perspective was adopted by not limiting our investigation to specific medication categories. Instead, we treat the act of requesting as a communicative behavior, separate from the pharmacological context.

METHOD

A comprehensive search across various online databases was performed. Two authors independently contributed the screening phase. The selection of articles and the data extraction were performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) flowchart.

RESULTS

Patient's request demonstrated to be a driving factor for physician's prescribing behavior not only when antibiotics are involved, but as a more generalized trend.

CONCLUSIONS

The study acknowledges the complexity of patient-provider communication, emphasizing the asymmetry in roles and the tension between patient empowerment and medical expertise. By uncovering the underlying mechanisms shaping doctors' responses to patient requests, this systematic review enhances our understanding of communication in healthcare settings.

PRACTICE IMPLICATIONS

Understanding the impact of patient requests on prescribing decisions highlights the importance of training healthcare providers in effective communication strategies that balance patient autonomy with clinical judgment. These insights can inform guidelines and interventions aimed at managing patient expectations, supporting more evidence-based prescribing practices and fostering better doctor-patient relationships.

Brain Cytochrome P450: Navigating Neurological Health and Metabolic Regulation

Human cytochrome P450 (CYP) enzymes in the brain represent a crucial frontier in neuroscience, with far-reaching implications for drug detoxification, cellular metabolism, and the progression of neurodegenerative diseases. The brain's complex architecture, composed of interconnected cell types and receptors, drives unique neuronal signaling pathways, modulates enzyme functions, and leads to distinct CYP gene expression and regulation patterns compared to the liver. Despite their relatively low levels of expression, brain CYPs exert significant influence on drug responses, neurotoxin susceptibility, behavior, and neurological disease risk. These enzymes are essential for maintaining brain homeostasis, mediating cholesterol turnover, and synthesizing and metabolizing neurochemicals, neurosteroids, and neurotransmitters. Moreover, they are key participants in oxidative stress responses, neuroprotection, and the regulation of inflammation. In addition to their roles in metabolizing psychotropic drugs, substances of abuse, and endogenous compounds, brain CYPs impact drug efficacy, safety, and resistance, underscoring their importance beyond traditional drug metabolism. Their involvement in critical physiological processes also links them to neuroprotection, with significant implications for the onset and progression of neurodegenerative diseases. Understanding the roles of cerebral CYP enzymes is vital for advancing neuroprotective strategies, personalizing treatments for brain disorders, and developing CNS-targeting therapeutics. This review explores the emerging roles of CYP enzymes, particularly those within the CYP1-3 and CYP46 families, highlighting their functional diversity and the pathological consequences of their dysregulation on neurological health. It also examines the potential of cerebral CYP-based biomarkers to improve the diagnosis and treatment of neurodegenerative disorders, offering new avenues for therapeutic innovation.

Opioid reward and deep brain stimulation of the lateral hypothalamic area

Opioid use disorder (OUD) is considered a global health issue that affects various aspects of patients' lives and poses a considerable burden on society. Due to the high prevalence of remissions and relapses, novel therapeutic approaches are required to manage OUD. Deep brain stimulation (DBS) is one of the most promising clinical breakthroughs in translational neuroscience. It involves stereotactically implanting electrodes inside the brain and transmitting electrical pulses to targeted areas. To date, the nucleus accumbens has been recognized as the most successful DBS target for treating different types of drug addiction. Nevertheless, further preclinical research is required to determine the optimal brain target and stimulation parameters. On the other hand, the lateral hypothalamic area (LHA) plays a crucial role in many motivated behaviors including food intake and drug-seeking. Additionally, it projects widely throughout the brain to reward-related areas like the ventral tegmental area. Therefore, this chapter reviews studies investigating the potential positive effects of DBS administration in the LHA in animal models of opioid dependence and other pathological conditions. Findings reveal that LHA has the potential to be targeted for DBS application to treat a wide variety of disorders such as opioid dependence, obesity, and sleep disorders without significant adverse events. However, in the context of opioid dependence, more studies are needed, based on more valid animal models of addiction, including self-administration paradigms and varying stimulation patterns, to indicate that LHA is a safe and effective target for DBS in subjects with refractory opioid dependence.

Differential DNA methylation in iPSC-derived dopaminergic neurons: a step forward on the role of SNORD116 microdeletion in the pathophysiology of addictive behavior in Prader-Willi syndrome

INTRODUCTION

A microdeletion including the SNORD116 gene (SNORD116 MD) has been shown to drive the Prader-Willi syndrome (PWS) features. PWS is a neurodevelopmental disorder clinically characterized by endocrine impairment, intellectual disability and psychiatric symptoms such as a lack of emotional regulation, impulsivity, and intense temper tantrums with outbursts. In addition, this syndrome is associated with a nutritional trajectory characterized by addiction-like behavior around food in adulthood. PWS is related to the genetic loss of expression of a minimal region that plays a potential role in epigenetic regulation. Nevertheless, the role of the SNORD116 MD in DNA methylation, as well as the impact of the oxytocin (OXT) on it, have never been investigated in human neurons.

METHODS

We studied the methylation marks in induced pluripotent stem-derived dopaminergic neurons carrying a SNORD116 MD in comparison with those from an age-matched adult healthy control. We also performed identical neuron differentiation in the presence of OXT. We performed a genome-wide DNA methylation analysis from the iPSC-derived dopaminergic neurons by reduced-representation bisulfite sequencing. In addition, we performed RNA sequencing analysis in these iPSC-derived dopaminergic neurons differentiated with or without OXT.

RESULTS

The analysis revealed that 153,826 cytosines were differentially methylated between SNORD116 MD neurons and control neurons. Among the differentially methylated genes, we determined a list of genes also differentially expressed. Enrichment analysis of this list encompassed the dopaminergic system with COMT and SLC6A3. COMT displayed hypermethylation and under-expression in SNORD116 MD, and SLC6A3 displayed hypomethylation and over-expression in SNORD116 MD. RT-qPCR confirmed significant over-expression of SLC6A3 in SNORD116 MD neurons. Moreover, the expression of this gene was significantly decreased in the case of OXT adjunction during the differentiation.

CONCLUSION

SNORD116 MD dopaminergic neurons displayed differential methylation and expression in the COMT and SLC6A3 genes, which are related to dopaminergic clearance.

A Conceptual Analysis of Opioid Use Disorder in Chronic Noncancer Pain Using Rodger's Evolutionary Approach

OBJECTIVE

This study aims to examine the complex nature of opioid use disorder (OUD) in chronic noncancer pain (CNCP) by exploring its antecedents, attributes, consequences, and interrelated concepts.

DESIGN

A systematic literature review was conducted to gather relevant studies published between 2015 and 2022, utilizing the CINAHL, MEDLINE, PsycINFO, and PubMed databases.

DATA SOURCES

The selected databases provided a comprehensive range of articles related to OUD in CNCP, ensuring a comprehensive topic analysis.

METHODS

Twenty-two articles meeting the inclusion criteria were included in the analysis. These articles were critically reviewed and analyzed to identify key themes and concepts related to OUD in CNCP.

RESULTS

The findings of this study shed light on the multifaceted aspects of OUD in CNCP, including its antecedents, such as goals of physical function improvement, prescription of opioids for CNCP, social influences, and mental health dynamics. The attributes of OUD in CNCP were identified as chronic pain, noncancer pain, opioid use, misuse, and abuse. OUD's consequences in CNCP include impaired functioning, increased health risks, psychological distress, social challenges, and economic burden.

CONCLUSION

Understanding the complexity of OUD in CNCP is crucial for improving patient outcomes. Collaborative efforts among healthcare systems, regulatory bodies, and professional organizations are needed to develop policies promoting safe and effective pain management while mitigating risks associated with opioid use in CNCP.

IMPLICATIONS FOR PRACTICE

Implementing policy recommendations derived from this study enhances care and outcomes for individuals with CNCP. By addressing complex issues of OUD in CNCP and adopting evidence-based practices, healthcare providers can optimize pain management and promote well-being in CNCP patients.

Genes associated with cortical thickness alterations in behavioral addiction

Behavioral addiction (BA) is a conceptually new addictive phenotype characterized by compulsive reward-seeking behaviors despite adverse consequences. Currently, its underlying neurogenetic mechanism remains unclear. Here, this study aimed to investigate the association between cortical thickness (CTh) and genetic phenotypes in BA. We conducted a systematic search in five databases and extracted gene expression data from the Allen Human Brain Atlas. Meta-analysis of 10 studies (343 addicted individuals and 355 controls) revealed that the BA group showed thinner CTh in the precuneus, postcentral gyrus, orbital-frontal cortex, and dorsolateral prefrontal cortex (P < 0.005). Meta-regression showed that the CTh in the precuneus and postcentral gyrus were negatively associated with the addiction severity (P < 0.0005). More importantly, the CTh phenotype of BA was spatially correlated with the expression of 12 genes (false discovery rate [FDR] < 0.05), and the dopamine D2 receptor had the highest correlation (rho = 0.55). Gene enrichment analysis further revealed that the 12 genes were involved in the biological processes of behavior regulation and response to stimulus (FDR < 0.05). In conclusion, our findings demonstrated the thinner CTh in cognitive control-related brain areas in BA, which could be associated with the expression of genes involving dopamine metabolism and behavior regulation.

Review of Opioid Abuse-Deterrent Formulations: Impact and Barriers to Access

The misuse and abuse of opioid analgesics continue to pose a serious public health concern, but for some patients, opioids remain an important analgesic option. Extended-release (ER) opioid formulations are effective for treating chronic pain and are supported by multiple 12-week efficacy studies. ER opioids often contain a high opioid content, and similar to immediate-release (IR) formulations, are subject to abuse, misuse, and diversion. Unintentional misuse may also occur when ER formulations are manipulated for medicinal administration, such as crushing a dose for easier oral intake. As part of a multipronged strategy designed to fight the opioid epidemic, abuse-deterrent formulations (ADFs) were developed to deter misuse, abuse, and diversion of opioids by making manipulation more difficult and nonoral routes of administration less rewarding. Although ADF opioids have been shown to decrease rates of abuse and diversion, they are not equally effective in terms of deterring manipulation for abuse or misuse. Xtampza ER utilizes DETERx technology, which allows it to retain ER characteristics when chewed or crushed, making it the only ER opioid without a boxed warning against these types of manipulation. OxyContin was also developed as an ADF but uses RESISTEC technology, making the tablet hard to crush and viscous in aqueous solutions. ADF utilization has been hampered by patient access issues, including high prices due to lack of insurance coverage. Postmarket real-world studies demonstrate lower rates of abuse, misuse, and diversion for ADF ER opioids compared with non-ADF formulations. However, similar studies comparing abuse-related effectiveness and health care costs for ADF opioids are warranted if clinicians are expected to utilize these potentially safer opioid formulations. These studies would support further education surrounding the benefits and utilization of ADFs and manipulation potential of different ADFs.

Risk and Resilience Variants in the Retinoic Acid Metabolic and Developmental Pathways Associated with Risk of FASD Outcomes

Fetal Alcohol Spectrum Disorder (FASD) is a common neurodevelopmental disorder that affects an estimated 2-5% of North Americans. FASD is induced by prenatal alcohol exposure (PAE) during pregnancy and while there is a clear genetic contribution, few genetic factors are currently identified or understood. In this study, using a candidate gene approach, we performed a genetic variant analysis of retinoic acid (RA) metabolic and developmental signaling pathway genes on whole exome sequencing data of 23 FASD-diagnosed individuals. We found risk and resilience alleles in ADH and ALDH genes known to normally be involved in alcohol detoxification at the expense of RA production, causing RA deficiency, following PAE. Risk and resilience variants were also identified in RA-regulated developmental pathway genes, especially in SHH and WNT pathways. Notably, we also identified significant variants in the causative genes of rare neurodevelopmental disorders sharing comorbidities with FASD, including STRA6 (Matthew-Wood), SOX9 (Campomelic Dysplasia), FDG1 (Aarskog), and 22q11.2 deletion syndrome (TBX1). Although this is a small exploratory study, the findings support PAE-induced RA deficiency as a major etiology underlying FASD and suggest risk and resilience variants may be suitable biomarkers to determine the risk of FASD outcomes following PAE.

Utility of polygenic scores across diverse diseases in a hospital cohort for predictive modeling

Polygenic scores estimate genetic susceptibility to diseases. We systematically calculated polygenic scores across 457 phenotypes using genotyping array data from China Medical University Hospital. Logistic regression models assessed polygenic scores' ability to predict disease traits. The polygenic score model with the highest accuracy, based on maximal area under the receiver operating characteristic curve (AUC), is provided on the GeneAnaBase website of the hospital. Our findings indicate 49 phenotypes with AUC greater than 0.6, predominantly linked to endocrine and metabolic diseases. Notably, hyperplasia of the prostate exhibited the highest disease prediction ability (P value = 1.01 × 10-19, AUC = 0.874), highlighting the potential of these polygenic scores in preventive medicine and diagnosis. This study offers a comprehensive evaluation of polygenic scores performance across diverse human traits, identifying promising applications for precision medicine and personalized healthcare, thereby inspiring further research and development in this field.

Novel endomorphin analogues CEMR-1 and CEMR-2 produce potent and long-lasting antinociception with a favourable side effect profile at the spinal level

BACKGROUND AND PURPOSE

Endomorphins have shown great promise as pharmaceutics for the treatment of pain. We have previously confirmed that novel endomorphin analogues CEMR-1 and CEMR-2 behaved as potent μ agonists and displayed potent antinociceptive activities at the supraspinal and peripheral levels. The present study was undertaken to evaluate the antinociceptive properties of CEMR-1 and CEMR-2 following intrathecal (i.t.) administration. Furthermore, their antinociceptive tolerance and opioid-like side effects were also determined.

EXPERIMENTAL APPROACH

The spinal antinociceptive effects of CEMR-1 and CEMR-2 were determined in a series of pain models, including acute radiant heat paw withdrawal test, spared nerve injury-induced neuropathic pain, complete Freund's adjuvant-induced inflammatory pain, visceral pain and formalin pain. Antinociceptive tolerance was evaluated in radiant heat paw withdrawal test.

KEY RESULTS

Spinal administration of CEMR-1 and CEMR-2 produced potent and prolonged antinociceptive effects in acute pain. CEMR-1 and CEMR-2 may produce their antinociception through distinct μ receptor subtypes. These two analogues also exhibited significant analgesic activities in neuropathic, inflammatory, visceral and formalin pain at the spinal level. It is noteworthy that CEMR-1 showed non-tolerance-forming analgesic properties, while CEMR-2 exhibited substantially reduced antinociceptive tolerance. Furthermore, both analogues displayed no or reduced side effects on conditioned place preference response, physical dependence, locomotor activity and gastrointestinal transit.

CONCLUSIONS AND IMPLICATIONS

The present investigation demonstrated that CEMR-1 and CEMR-2 displayed potent and long-lasting antinociception with a favourable side effect profile at the spinal level. Therefore, CEMR-1 and CEMR-2 might serve as promising analgesic compounds with minimal opioid-like side effects.

Medications for opioid use disorder: An interactive educational program developed for the nurse practitioner curriculum

ABSTRACT

Opioid overdose deaths remain a major public health concern in the United States and led to the recent changes in regulations that allow nurse practitioners (NPs) to prescribe buprenorphine without the previously required Drug Addiction Treatment Act waiver. Previously, waiver requirements included 24 hours of opioid use disorder (OUD) and medications for OUD (MOUD) training. Although this training is no longer required, NPs need education related to providing nonstigmatizing care to individuals with OUD and safe MOUD prescribing practices. A combination of online didactic modules, in-person simulation activities, and experiential learning was provided to psychiatric mental health NP (PMHNP) and family NP (FNP) students enrolled in a Doctor of Nursing Practice (DNP) program. OUD was presented through a chronic care lens to normalize treatment and decrease stigma, and harm reduction principles were included to increase safe prescribing of MOUD. Fifty-six students completed the didactic training, 51 students participated in the simulation, and 11 students completed shadowing experiences with an experienced MOUD provider. Psychiatric mental health NP and FNP graduates of this DNP program have the knowledge and skills to provide MOUD to individuals struggling with OUD, thus potentially increasing access to care and decreasing overdose deaths.

Machine learning assisted-nanomedicine using magnetic nanoparticles for central nervous system diseases

Magnetic nanoparticles possess unique properties distinct from other types of nanoparticles developed for biomedical applications. Their unique magnetic properties and multifunctionalities are especially beneficial for central nervous system (CNS) disease therapy and diagnostics, as well as targeted and personalized applications using image-guided therapy and theranostics. This review discusses the recent development of magnetic nanoparticles for CNS applications, including Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, and drug addiction. Machine learning (ML) methods are increasingly applied towards the processing, optimization and development of nanomaterials. By using data-driven approach, ML has the potential to bridge the gap between basic research and clinical research. We review ML approaches used within the various stages of nanomedicine development, from nanoparticle synthesis and characterization to performance prediction and disease diagnosis.

Targeting Opioid Receptors in Addiction and Drug Withdrawal: Where Are We Going?

This review article offers an outlook on the use of opioids as therapeutics for treating several diseases, including cancer and non-cancer pain, and focuses the analysis on the opportunity to target opioid receptors for treating opioid use disorder (OUD), drug withdrawal, and addiction. Unfortunately, as has been well established, the use of opioids presents a plethora of side effects, such as tolerance and physical and physiological dependence. Accordingly, considering the great pharmacological potential in targeting opioid receptors, the identification of opioid receptor ligands devoid of most of the adverse effects exhibited by current therapeutic agents is highly necessary. To this end, herein, we analyze some interesting molecules that could potentially be useful for treating OUD, with an in-depth analysis regarding in vivo studies and clinical trials.

The Use of Oxytocin for the Treatment of Opioid Use Disorder

Nearly 27 million people have an opioid use disorder (OUD) according to the 2016 Global Burden of Disease study, most of which occur in the US where opioids are a common class of medication used to treat acute and chronic pain. In 2016 alone, more than 60 million patients had at least one prescription for opioids filled or refilled. Over the past decade, prescription rates have risen astronomically and have created an epidemic in the US dubbed the "opioid crisis." In this regard, there has been an increase in overdoses and OUD diagnoses. Several studies have found dysregulation of balance between several neurotransmitters involved in the neural circuitry that subserves several behavioral domains, such as reward recognition, motivation, learning, and memory, affect, stress, and executive function, that contribute to the manifestation of craving. On the horizon is a new treatment approach consisting of the neuropeptide oxytocin, which may be involved in the overlapping mechanisms of stable attachment formation and coping with stress. Through this mechanism, it can shift processing from novelty and reward-seeking to an appreciation of familiarity and thus reduce stress and increase resilience in the face of addiction. It has been hypothesized that there is a connection between the glutaminergic and oxytocinergic systems, making oxytocin a possible therapeutic agent in reducing drug-induced actions seen in OUD patients. This manuscript will review the potential and feasible use of oxytocin in treating OUD.

Insights into the mechanisms underlying opioid use disorder and potential treatment strategies

Opioid use disorder is a worldwide societal problem and public health burden. Strategies for treating opioid use disorder can be divided into those that target the opioid receptor system and those that target non-opioid receptor systems, including the dopamine and glutamate receptor systems. Currently, the clinical drugs used to treat opioid use disorder include the opioid receptor agonists methadone and buprenorphine, which are limited by their abuse liability, and the opioid receptor antagonist naltrexone, which is limited by poor compliance. Therefore, the development of effective medications with lower abuse liability and better potential for compliance is urgently needed. Based on recent advances in the understanding of the neurobiological mechanisms underlying opioid use disorder, potential treatment strategies and targets have emerged. This review focuses on the progress made in identifying potential targets and developing medications to treat opioid use disorder, including progress made by our laboratory, and provides insights for future medication development. LINKED ARTICLES: This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

Machine-learning analysis of opioid use disorder informed by MOR, DOR, KOR, NOR and ZOR-based interactome networks

Opioid use disorder (OUD) continuously poses major public health challenges and social implications worldwide with dramatic rise of opioid dependence leading to potential abuse. Despite that a few pharmacological agents have been approved for OUD treatment, the efficacy of said agents for OUD requires further improvement in order to provide safer and more effective pharmacological and psychosocial treatments. Proteins including mu, delta, kappa, nociceptin, and zeta opioid receptors are the direct targets of opioids and play critical roles in therapeutic treatments. The protein-protein interaction (PPI) networks of the these receptors increase the complexity in the drug development process for an effective opioid addiction treatment. The report below presents a PPI-network informed machine-learning study of OUD. We have examined more than 500 proteins in the five opioid receptor networks and subsequently collected 74 inhibitor datasets. Machine learning models were constructed by pairing gradient boosting decision tree (GBDT) algorithm with two advanced natural language processing (NLP)-based autoencoder and Transformer fingerprints for molecules. With these models, we systematically carried out evaluations of screening and repurposing potential of more than 120,000 drug candidates for four opioid receptors. In addition, absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties were also considered in the screening of potential drug candidates. Our machine-learning tools determined a few inhibitor compounds with desired potency and ADMET properties for nociceptin opioid receptors. Our approach offers a valuable and promising tool for the pharmacological development of OUD treatments.

Exercise training augments brain function and reduces pain perception in adults with chronic pain: A systematic review of intervention studies

Introduction

Chronic pain (CP) is a leading cause of disability worldwide. Pain may be measured using subjective questionnaires, but understanding the underlying physiology, such as brain function, could improve prognosis. Further, there has been a shift towards cost-effective lifestyle modification for the management of CP.

Methods

We conducted a systematic review (Registration: #CRD42022331870) using articles retrieved from four databases (Pubmed, EMBASE, AMED, and CINAHL) to assess the effect of exercise on brain function and pain perception/quality of life in adults with CP.

Results

Our search yielded 1879 articles; after exclusion, ten were included in the final review. Study participants were diagnosed with either osteoarthritis or fibromyalgia. However, two studies included "fibromyalgia and low back pain" or "fibromyalgia, back, and complex regional pain." Exercise interventions that were 12 weeks or longer (n = 8/10) altered brain function and improved pain and/or quality of life outcomes. The cortico-limbic pathway, default-mode network, and dorsolateral prefrontal cortex were key regions that experienced alterations post-intervention. All studies that reported an improvement in brain function also demonstrated an improvement in pain perception and/or quality of life.

Discussion

Our review suggests that alterations in brain function, notably the cortico-limbic, default-mode and dorsolateral prefrontal cortex, may be responsible for the downstream improvements in the subjective experience of CP. Through appropriate programming (i.e., length of intervention), exercise may represent a viable option to manage CP via its positive influence on brain health.

Impact of an Alcohol-based hand sanitizer usage during COVID-19 pandemic on disulfiram treatment: A South Indian psychiatrist's practice experiences

Background: Alcohol-based hand sanitizer (ABHS) usage has become one of the COVID-19 pandemic-related adapted responses. Some disulfiram-ethanol reactions are reported in people who use alcohol-based hand rub/sanitizer and take Disulfiram as a treatment for their alcohol use disorders. Aim & Objective: To determine the practice experiences of psychiatrists on disulfiram prescription to alcohol use disorder victims. Methodology: A cross-sectional study on the psychiatrists to find the experiences of disulfiram prescription to their clients with alcohol use disorders during the COVID-19 pandemic. Results: Nearly 84 (51%) were reverted with a completed questionnaire. Among the respondents, 28 (33.3%) of the respondents decreased to prescribe Disulfiram, 48 (57.1%) reported that their patients stopped using ABHS due to fear of Disulfiram-Ethanol Reaction (DER), and 20 (23.8%) responders notified that their patients were expressed their worry on DER with Disulfiram and ABHS. Conclusion: Disulfiram prescribed for alcohol use disorders; treatment got peculiar experiences with the incidences of DER reported with Alcohol-based hand sanitizer. Many practitioners were scared to prescribe disulfiram due to DER with ABHS. The prevailing evidence that there is no possibility of cutaneous application of ABHS producing enough significant DER. Hence using ABHS is not a contraindication for disulfiram prescription.

Opening the amino acid toolbox for peptide-based NTS2-selective ligands as promising lead compounds for pain management

Chronic pain is one of the most critical health issues worldwide. Despite considerable efforts to find therapeutic alternatives, opioid drugs remain the gold standard for pain management. The administration of μ-opioid receptor (MOR) agonists is associated with detrimental and limiting adverse effects. Overall, these adverse effects strongly overshadow the effectiveness of opioid therapy. In this context, the development of neurotensin (NT) ligands has shown to be a promising approach for the management of chronic and acute pain. NT exerts its opioid-independent analgesic effects through the binding of two G protein-coupled receptors (GPCRs), NTS1 and NTS2. In the last decades, modified NT analogues have been proven to provide potent analgesia in vivo. However, selective NTS1 and nonselective NTS1/NTS2 ligands cause antinociception associated with hypothermia and hypotension, whereas selective NTS2 ligands induce analgesia without altering the body temperature and blood pressure. In light of this, various structure-activity relationship (SAR) studies provided findings addressing the binding affinity of ligands towards NTS2. Herein, we comprehensively review peptide-based NTS2-selective ligands as a robust alternative for future pain management. Particular emphasis is placed on SAR studies governing the desired selectivity and associated in vivo results.

Role of microRNA-132 in Opioid Addiction through Modification of Neural Stem Cell Differentiation

In this editorial, we focused on the article, "MicroRNA-132 in the Adult Dentate Gyrus is Involved in Opioid Addiction Via Modifying the Differentiation of Neural Stem Cells" by Jia and colleagues [...].

Historical Pathways for Opioid Addiction, Withdrawal with Traditional and Alternative Treatment Options with Ketamine, Cannabinoids, and Noribogaine: A Narrative Review

Even as prescription opioid dispensing rates have begun to decrease, the use of illicit opioids such as heroin and fentanyl has increased. Thus, the end of the opioid epidemic is not in sight, and treating patients that are addicted to opioids remains of utmost importance. Currently, the primary pharmacotherapies used to treat opioid addiction over the long term are the opioid antagonist naltrexone, the partial-agonist buprenorphine, and the full agonist methadone. Naloxone is an antagonist used to rapidly reverse opioid overdose. While these treatments are well-established and used regularly, the gravity of the opioid epidemic necessitates that all possible avenues of treatment be explored. Therefore, in this narrative review, we analyze current literature regarding use of the alternative medications ketamine, noribogaine, and cannabinoids in treating patients suffering from opioid use disorder. Beyond its use as an anesthetic, ketamine has been shown to have many applications in several medical specialties. Of particular interest to the subject at hand, ketamine is promising in treating individuals addicted to opioids, alcohol, and cocaine. Therapeutically administered cannabinoids have been proposed for the treatment of multiple illnesses. These include, but are not limited to epilepsy, Parkinson's disease, multiple sclerosis, chronic pain conditions, anxiety disorders, and addiction. The cannabinoid dronabinol has been seen to have varying effects. High doses appear to reduce withdrawal symptoms but this comes at the expense of increased adverse side effects such as sedation and tachycardia. Noribogaine is a weak MOR antagonist and relatively potent KOR agonist, which may explain the clinical anti-addictive effects. More research should be done to assess the viability of these medications for the treatment of OUD and withdrawal.

Mechanism of opioid addiction and its intervention therapy: Focusing on the reward circuitry and mu-opioid receptor

Opioid abuse and addiction have become a global pandemic, posing tremendous health and social burdens. The rewarding effects and the occurrence of withdrawal symptoms are the two mainstays of opioid addiction. Mu-opioid receptors (MORs), a member of opioid receptors, play important roles in opioid addiction, mediating both the rewarding effects of opioids and opioid withdrawal syndrome (OWS). The underlying mechanism of MOR-mediated opioid rewarding effects and withdrawal syndrome is of vital importance to understand the nature of opioid addiction and also provides theoretical basis for targeting MORs to treat drug addiction. In this review, we first briefly introduce the basic concepts of MORs, including their structure, distribution in the nervous system, endogenous ligands, and functional characteristics. We focused on the brain circuitry and molecular mechanism of MORs-mediated opioid reward and withdrawal. The neuroanatomical and functional elements of the neural circuitry of the reward system underlying opioid addiction were thoroughly discussed, and the roles of MOR within the reward circuitry were also elaborated. Furthermore, we interrogated the roles of MORs in OWS, along with the structural basis and molecular adaptions of MORs-mediated withdrawal syndrome. Finally, current treatment strategies for opioid addiction targeting MORs were also presented.

A steady stream of knowledge: decreased urinary retention after implementation of ERAS protocols in ambulatory minimally invasive inguinal hernia repair

BACKGROUND

Potential complications after inguinal hernia repair include uncontrolled post-operative pain and post-operative urinary retention (POUR). Enhanced Recovery After Surgery (ERAS) protocols aim to mitigate post-operative morbidity. We study the impact of ERAS measures alongside discharge without a narcotic prescription on post-operative pain and POUR after minimally invasive inguinal hernia repair.

METHODS

A retrospective review of a prospectively maintained database identified patients that underwent minimally invasive inguinal hernia repair at a single institution. Intra-operative data included operative time, narcotic usage, non-narcotic adjunct medication, and fluid administration. Primary outcomes included rates of POUR and uncontrolled post-operative pain. Operations performed after 2018 were included in the ERAS cohort. Uncontrolled post-operative pain was defined as needing additional narcotic prescriptions, admission, or ER visits for post-operative pain. POUR was defined as requiring an indwelling urethral catheter at discharge, admission for retention, or returning to the ER for urinary retention.

RESULTS

Between January 2008 and March 2021, 1097 patients who underwent minimally invasive inguinal hernia repair were identified. 91.3% of these procedures were laparoscopic and 8.7% were robotic. Average patient age was 57.4 years, 93% were male. Patients receiving care after initiation of the ERAS protocol were significantly less likely to experience POUR when compared to their prior counterparts (1.4% vs. 4.2% p = 0.01); there was no difference in post-operative pain complications (1.4% vs. 2.9% p = 0.15). Patients who were discharged without a narcotic prescription had 0% incidence of POUR. Significant differences were found between the ERAS and non-ERAS cohort regarding narcotic usage and fluid administration. Age, higher fluid volume, and higher narcotic usage were found to be risk factors for POUR while ERAS, sugammadex, and dexamethasone were found to be protective.

CONCLUSION

Implementation of an ambulatory ERAS protocol can significantly decrease urinary retention and narcotic usage rates after minimally invasive inguinal hernia repair.

Deep brain stimulation for opioid use disorder: A systematic review of preclinical and clinical evidence

Opioid use disorder (OUD) is a chronic and complex disease characterized by repeated relapses and remissions. Deep brain stimulation (DBS) has been discussed again and again as a potentially helpful neuromodulatory procedure in this context. In this review, for the first time, we intended to systematically identify the positive and negative effects of DBS in human and animal models of opioid dependence to assess the viability of DBS as a treatment of OUD. Eligible studies were incorporated by a comprehensive literature search and evaluated through proper methodological quality assessment tools. Findings showed that the nucleus accumbens was the most stimulated brain target in human and animal studies, and DBS was applied chiefly in the form of high-frequency stimulation (HFS). DBS administration effectively reduced opioid craving and consumption in human and animal subjects dependent on opioids. DBS represents a valuable alternative strategy for treating intractable opioid addiction. Based on our systematic literature analysis, research efforts in this field should be continued.

Survey of Opioid Risk Tool Among Cancer Patients Receiving Opioid Analgesics

BACKGROUND

The risk of opioid-related aberrant behavior (OAB) in Korean cancer patients has not been previously evaluated. The purpose of this study is to investigate the Opioid Risk Tool (ORT) in Korean cancer patients receiving opioid treatment.

METHODS

Data were obtained from a multicenter, cross-sectional, nationwide observational study regarding breakthrough cancer pain. The study was conducted in 33 South Korean institutions from March 2016 to December 2017. Patients were eligible if they had cancer-related pain within the past 7 days, which was treated with strong opioids in the previous 7 days.

RESULTS

We analyzed ORT results of 946 patients. Only one patient in each sex (0.2%) was classified as high risk for OAB. Moderate risk was observed in 18 males (3.3%) and in three females (0.7%). Scores above 0 were primarily derived from positive responses for personal or familial history of alcohol abuse (in men), or depression (in women). In patients with an ORT score of 1 or higher (n = 132, 14%), the score primarily represented positive responses for personal history of depression (in females), personal or family history of alcohol abuse (in males), or 16-45 years age range. These patients had more severe worst and average pain intensity (proportion of numeric rating scale ≥ 4: 20.5% vs. 11.4%, P < 0.001) and used rescue analgesics more frequently than patients with ORT scores of 0. The proportion of moderate- or high-risk patients according to ORT was lower in patients receiving low doses of long-acting opioids than in those receiving high doses (2.0% vs. 6.6%, P = 0.031). Moderate or high risk was more frequent when ORT was completed in an isolated room than in an open, busy place (2.7% vs. 0.6%, P = 0.089).

CONCLUSIONS

The score of ORT was very low in cancer patients receiving strong opioids for analgesia. Higher pain intensity may associate with positive response to one or more ORT item.

Acute Hydronephrosis Secondary to Methadone-Induced Constipation

Opioid-induced constipation is a significant medical problem accounting for over 40% to 60% of patients without cancer receiving opioids. We report a unique case of a 71-year-old male with a history of opioid use disorder now on methadone maintenance presenting with severe opioid-induced constipation and fecal impaction causing extrinsic compression on the right-sided ureter resulting in right hydronephrosis and hydroureter that improved with aggressive bowel regime with the stool softener, laxatives and enemas.

Methadone alone can predispose to hydroureter with hydronephrosis due to external compression from the severe intestinal dilation secondary to opioid-induced constipation.

[Comorbidity of posttraumatic stress disorder and addiction from a biopsychosocial perspective]

Posttraumatic stress disorder and substance use disorder often co-occur within the health care system. Their comorbidity is associated with more serious acute clinical symptomatology, more frequent hospital admissions in state of emergency and significantly lower chances of improvement by psychological and pharmacological treatment. Their comorbidity contributes to dramatically unfavourable courses of illness as regards all biopsychosocial levels. The survey presented will discuss empirical findings from various perspectives: general epidemiology, substance use disorder as risk factor of trauma and PTSD, trauma and PTSD as risk factor of SUD, neurobiological effects of SUD converging towards neurobiology of PTSD, shared common factors of genetics/epigenetics, personality traits, and early developmental stress and trauma. The main focus of analysis will be put on processes that are intrinsically linked to the development and course of both disorders.

A Review of DNA Risk Alleles to Determine Epigenetic Repair of mRNA Expression to Prove Therapeutic Effectiveness in Reward Deficiency Syndrome (RDS): Embracing "Precision Behavioral Management"

This is a review of research on "Precision Behavioral Management" of substance use disorder (SUD). America is experiencing a high prevalence of substance use disorder, primarily involving legal and illegal opioid use. A 3000% increase in treatment for substance abuse has occurred between 2000 and 2016. Unfortunately, present day treatment of opioid abuse involves providing replacement therapy with powerful opioids to, at best, induce harm reduction, not prophylaxis. These interventions do not enhance gene expression and restore the balance of the brain reward system's neurotransmitters. We are proposing a generalized approach called "Precision Behavioral Management". This approach includes 1) using the Genetic Addiction Risk Severity (GARS, a 10 candidate polymorphic gene panel shown to predict ASI-alcohol and drug severity) to assess early pre-disposition to substance use disorder; 2) using a validated reward deficiency syndrome (RDS) questionnaire; 3) utilization of the Comprehensive Analysis of Reported Drugs (CARD™) to assess treatment compliance and abstinence from illicit drugs during treatment, and, importantly; 4) utilization of a "Pro-dopamine regulator (KB220)" (via IV or oral [KB220Z] delivery systems) to optimize gene expression, restore the balance of the Brain Reward Cascade's neurotransmitter systems and prevent relapse by induction of dopamine homeostasis, and; 5) utilization of targeted DNA polymorphic reward genes to direct mRNA genetic expression profiling during the treatment process. Incorporation of these events can be applied to not only the under-considered African-American RDS community, but all victims of RDS, as a demonstration of a paradigm shift that uniquely provides a novel putative "standard of care" based on DNA guided precision nutrition therapy to induce "dopamine homeostasis" and rebalance neurotransmitters in the Brain Reward Cascade. We are also developing a Reward Deficiency Syndrome Diagnostic Criteria (RDSDC) to assist in potential tertiary treatment.

Estimating prevalence of human traits among populations from polygenic risk scores

The genetic basis of phenotypic variation across populations has not been well explained for most traits. Several factors may cause disparities, from variation in environments to divergent population genetic structure. We hypothesized that a population-level polygenic risk score (PRS) can explain phenotypic variation among geographic populations based solely on risk allele frequencies. We applied a population-specific PRS (psPRS) to 26 populations from the 1000 Genomes to four phenotypes: lactase persistence (LP), melanoma, multiple sclerosis (MS) and height. Our models assumed additive genetic architecture among the polymorphisms in the psPRSs, as is convention. Linear psPRSs explained a significant proportion of trait variance ranging from 0.32 for height in men to 0.88 for melanoma. The best models for LP and height were linear, while those for melanoma and MS were nonlinear. As not all variants in a PRS may confer similar, or even any, risk among diverse populations, we also filtered out SNPs to assess whether variance explained was improved using psPRSs with fewer SNPs. Variance explained usually improved with fewer SNPs in the psPRS and was as high as 0.99 for height in men using only 548 of the initial 4208 SNPs. That reducing SNPs improves psPRSs performance may indicate that missing heritability is partially due to complex architecture that does not mandate additivity, undiscovered variants or spurious associations in the databases. We demonstrated that PRS-based analyses can be used across diverse populations and phenotypes for population prediction and that these comparisons can identify the universal risk variants.

Pharmacogenomic Testing and Patient Perception Inform Pain Pharmacotherapy

(1) Background: Chronic pain is one of the most common reasons for individuals to seek medications. Historically, opioids have been the mainstay of chronic pain management. However, in some patient populations, opioids fail to demonstrate therapeutic efficacy, whereas in other populations, opioids may cause toxic effects, even at lower doses. Response to pain medication is affected by many factors, including an individual's genetic variations. Pharmacogenomic testing has been designed to help achieve optimal treatment outcomes. This study aimed at assessing the impact of CYP2D6 pharmacogenomic testing on physicians' choice in prescribing chronic pain medications and patient pain control. (2) Methods: This retrospective study reviewed 107 patient charts from a single site pain management center. All 107 patients received pharmacogenomic testing. The outcomes of interest were confirmation that the optimal pain medication is being administered or a change in the chronic pain medication is warranted as a result of the pharmacogenomic testing. The main independent variable was the pharmacogenomic test result. Other independent variables included patient gender, race, and comorbidities. The retrospective study was reviewed and approved by the Touro College and University System IRB, HSIRB1653E. (3) Results: Patients self-reported pain intensity on a scale of 1-10 before and after pharmacogenomic testing. Then, 100% of patients in the retrospective study were tested for their pain pharmacogenomic profile. Of the 107 patients participating in the study, more than 50% had their medications altered as a result of the pharmacogenomic testing. The percentage of patients with intense pain were decreased post-pharmacogenomic testing (5.6%) as compared to pre-pharmacogenomic testing (10.5%). Patients with intense, moderate, and mild pain categories were more likely to receive changes in pain medications. In contrast, patients with severe pain were less likely to receive a change in pain medication. Hispanic ethnicity was associated with a statistically significantly decrease in a pain scale category. Illegal drug abuse was associated with a decrease in pain scale category. Change in medication dose was associated with a decrease in pain scale category. (4) Conclusion: In this retrospective study, implementation of pharmacogenomic testing demonstrated significant benefits to patients with intense pain undergoing treatment.

Cost-utility analysis of single nucleotide polymorphism panel-based machine learning algorithm to predict risk of opioid use disorder

Aim: To conduct a cost-utility analysis of a novel genetic diagnostic test (OUDTEST) for risk of developing opioid use disorder for elective orthopedic surgery patients. Materials & Methods: A simulation model assessed cost-effectiveness and quality-adjusted life-years (QALYs) for OUDTEST from private insurer and self-insured employer perspectives over a 5-year time horizon for a hypothetical patient population. Results: OUDTEST was found to cost less and increase QALYs, over a 5-year period for private insurance (savings US$2510; QALYs 0.02) and self-insured employers (-US$2682; QALYs 0.02). OUDTEST was a dominant strategy in 71.1% (private insurance) and 72.7% (self-insured employer) of model iterations. Sensitivity analyses revealed robust results except for physician compliance. Conclusion: OUDTEST was expected to be a cost-effective solution for personalizing postsurgical pain management in orthopedic patients.

Opioid Addiction and Opioid Receptor Dimerization: Structural Modeling of the OPRD1 and OPRM1 Heterodimer and Its Signaling Pathways

Opioid addiction is a complex phenomenon with genetic, social, and other components. Due to such complexity, it is difficult to interpret the outcome of clinical studies, and thus, mutations found in individuals with these addictions are still not indisputably classified as opioid addiction-causing variants. Here, we computationally investigated two such mutations, A6V and N40D, found in the mu opioid receptor gene OPRM1. The mutations are located in the extracellular domain of the corresponding protein, which is important to the hetero-dimerization of OPRM1 with the delta opioid receptor protein (OPRD1). The hetero-dimerization of OPRD1-OPRM1 affects the signaling pathways activated by opioids and natural peptides and, thus, could be considered a factor contributing to addiction. In this study, we built four 3D structures of molecular pathways, including the G-protein signaling pathway and the β-arrestin signaling pathway of the heterodimer of OPRD1-OPRM1. We also analyzed the effect of mutations of A6V and N40D on the stability of individual OPRM1/OPRD1 molecules and the OPRD1-OPRM1 heterodimer with the goal of inferring their plausible linkage with opioid addiction. It was found that both mutations slightly destabilize OPRM1/OPRD1 monomers and weaken their association. Since hetero-dimerization is a key step for signaling processes, it is anticipated that both mutations may be causing increased addiction risk.

The role of glucagon-like peptide 1 (GLP-1) in addictive disorders

Drug-, alcohol- and tobacco use disorders are a global burden affecting millions of people. Despite decades of research, treatment options are sparse or missing, and relapse rates are high. Glucagon-like peptide-1 (GLP-1) is released in the small intestines, promotes blood glucose homeostasis, slows gastric emptying, and reduces appetite. GLP-1 receptor agonists approved for treating type 2 diabetes mellitus and obesity, have received attention as a potential anti-addiction treatment. Studies in rodents and non-human primates have demonstrated a reduction in intake of alcohol and drugs of abuse, and clinical trials have been initiated to investigate whether the preclinical findings can be translated to patients. This review will give an overview of current findings and discuss the possible mechanisms of action. We suggest that effects of GLP-1 in alcohol- and substance use disorder is mediated centrally, at least partly through dopamine signalling, but precise mechanisms are still to be uncovered.

Drug repurposing for opioid use disorders: integration of computational prediction, clinical corroboration, and mechanism of action analyses

Morbidity and mortality from opioid use disorders (OUD) and other substance use disorders (SUD) is a major public health crisis, yet there are few medications to treat them. There is an urgency to accelerate SUD medication development. We present an integrated drug repurposing strategy that combines computational prediction, clinical corroboration using electronic health records (EHRs) of over 72.9 million patients and mechanisms of action analysis. Among top-ranked repurposed candidate drugs, tramadol, olanzapine, mirtazapine, bupropion, and atomoxetine were associated with increased odds of OUD remission (adjusted odds ratio: 1.51 [1.38-1.66], 1.90 [1.66-2.18], 1.38 [1.31-1.46], 1.37 [1.29-1.46], 1.48 [1.25-1.76], p value < 0.001, respectively). Genetic and functional analyses showed these five candidate drugs directly target multiple OUD-associated genes including BDNF, CYP2D6, OPRD1, OPRK1, OPRM1, HTR1B, POMC, SLC6A4 and OUD-associated pathways, including opioid signaling, G-protein activation, serotonin receptors, and GPCR signaling. In summary, we developed an integrated drug repurposing approach and identified five repurposed candidate drugs that might be of value for treating OUD patients, including those suffering from comorbid conditions.

Oxycodone-paracetamol tablet exhibits increased analgesic efficacy for acute postoperative pain, higher satisfaction and comparable safety profiles compared with celecoxib in patients underwent arthroscopic knee surgery

This randomized, controlled study compared the efficacy and safety between oxycodone-paracetamol tablet and celecoxib for postoperative analgesia in patients who underwent arthroscopic knee surgery (AKS). Totally, 232 patients scheduled to undergo AKS were enrolled and were randomly assigned to either the oxycodone-paracetamol (OPT group) or the celecoxib group (CEL group). Pain at rest/motion (based on pain visual analog scale (VAS) score), rescue analgesia consumption, satisfaction level and adverse events were assessed after AKS. Pain VAS score at rest was decreased at 6 h, 12 h post-AKS in the OPT group compared with the CEL group. Similarly, pain VAS score at motion was reduced at 6 h, 12 h, 24 h post-AKS in the OPT group compared to the CEL group. Furthermore, both rescue analgesia rate (14.7% vs. 33.6%) and accumulated pethidine consumption (3.7 ± 8.9 mg vs. 14.0 ± 21.2 mg) were lower in OPT group compared with the CEL group. Patients satisfaction score was either at 24 h, 48 h in OPT group compared with the CEL group. Further subgroup analyses indicated that the effect of oxycodone-paracetamol versus (vs. celecoxib) on post-AKS management was more apparent in the elderly patients and male patients. In addition, the adverse events were well tolerable (including nausea, constipation, vomiting, drowsiness and dizziness) and were of no different between the two groups. In conclusion, oxycodone-paracetamol tablet presents increased analgesic efficacy for acute postoperative pain, with higher patient satisfaction and comparable safety profiles compared with celecoxib in patients underwent AKS.

Consensus Recommendations on the Treatment of Opioid Use Disorder in the Emergency Department

The treatment of opioid use disorder with buprenorphine and methadone reduces morbidity and mortality in patients with opioid use disorder. The initiation of buprenorphine in the emergency department (ED) has been associated with increased rates of outpatient treatment linkage and decreased drug use when compared to patients randomized to receive standard ED referral. As such, the ED has been increasingly recognized as a venue for the identification and initiation of treatment for opioid use disorder, but no formal American College of Emergency Physicians (ACEP) recommendations on the topic have previously been published. The ACEP convened a group of emergency physicians with expertise in clinical research, addiction, toxicology, and administration to review literature and develop consensus recommendations on the treatment of opioid use disorder in the ED. Based on literature review, clinical experience, and expert consensus, the group recommends that emergency physicians offer to initiate opioid use disorder treatment with buprenorphine in appropriate patients and provide direct linkage to ongoing treatment for patients with untreated opioid use disorder. These consensus recommendations include strategies for opioid use disorder treatment initiation and ED program implementation. They were approved by the ACEP board of directors in January 2021.

Can Src protein tyrosine kinase inhibitors be combined with opioid analgesics? Src and opioid-induced tolerance, hyperalgesia and addiction

The clinical application of opioids may be accompanied by a series of adverse consequences, such as opioid tolerance, opioid-induced hyperalgesia, opioid dependence or addiction. In view of this issue, clinicians are faced with the dilemma of treating various types of pain with or without opioids. In this review, we discuss that Src protein tyrosine kinase plays an important role in these adverse consequences, and Src inhibitors can solve these problems well. Therefore, Src inhibitors have the potential to be used in combination with opioids to achieve synergy. How to combine them together to maximize the analgesic effect while avoiding unnecessary trouble provides a topic for follow-up research.

Association between GABA receptor delta subunit gene polymorphisms and heroin addiction

Evidence suggests that γ-aminobutyric acid (GABA) receptors are involved in the development of drug dependence. Considering its exclusively extrasynaptic localization, GABA receptor delta subunit (GABRD) is likely involved in heroin addiction. The purpose of this study was to explore the association between the single nucleotide polymorphisms (SNPs) of GABRD and heroin addiction. Genotyping of five SNPs (rs13303344, rs4481796, rs2376805, rs2229110, and rs41307846) in GABRD gene was performed by using TaqMan SNP assay. The association between heroin addiction and these SNPs was assessed in 446 heroin dependent patients and 400 normal control subjects of male Han Chinese origin. Only the genotype and allele frequencies at rs13303344 differed significantly between the cases and controls (nominal P values were 0.028 and 0.019, respectively). The C allele of rs13303344 was associated with an increased risk of heroin addiction (OR = 1.281, 95 % CI: 1.042-1.575). After Bonferroni correction, the association lost significance. The frequencies of the haplotype C-C-A and A-C-A at GARBD (rs13303344-rs4481796- rs2376805) differed significantly between the cases and controls. The heroin craving score was significantly higher in patients with CC/AC genotypes at rs13303344 than in those with the AA genotype (nominal P = 0.017). The results suggest that GABRD rs13303344 may contribute to the susceptibility to heroin addiction and is associated with the drug cravings of heroin dependent patients.

Influence of G protein-biased agonists of μ-opioid receptor on addiction-related behaviors

Opioid analgesics remain a gold standard for the treatment of moderate to severe pain. However, their clinical utility is seriously limited by a range of adverse effects. Among them, their high-addictive potential appears as very important, especially in the context of the opioid epidemic. Therefore, the development of safer opioid analgesics with low abuse potential appears as a challenging problem for opioid research. Among the last few decades, different approaches to the discovery of novel opioid drugs have been assessed. One of the most promising is the development of G protein-biased opioid agonists, which can activate only selected intracellular signaling pathways. To date, discoveries of several biased agonists acting via μ-opioid receptor were reported. According to the experimental data, such ligands may be devoid of at least some of the opioid side effects, such as respiratory depression or constipation. Nevertheless, most data regarding the addictive properties of biased μ-opioid receptor agonists are inconsistent. A global problem connected with opioid abuse also requires the search for effective pharmacotherapy for opioid addiction, which is another potential application of biased compounds. This review discusses the state-of-the-art on addictive properties of G protein-biased μ-opioid receptor agonists as well as we analyze whether these compounds can diminish any symptoms of opioid addiction. Finally, we provide a critical view on recent data connected with biased signaling and its implications to in vivo manifestations of addiction.

Genomics and epigenomics of addiction

Recent progress in the genomics and epigenomics of addiction has contributed to improving our understanding of this complex mental disorder's etiology, filling the gap between genes, environment, and behavior. We review the behavioral genetic studies reporting gene and environment interactions that explain the polygenetic contribution to the resilience and vulnerability to develop addiction. We discuss the evidence of polymorphic candidate genes that confer susceptibility to develop addiction as well as the studies of specific epigenetic marks that contribute to vulnerability and resilience to addictive-like behavior. A particular emphasis has been devoted to the miRNA changes that are considered potential biomarkers. The increasing knowledge about the technology required to alter miRNA expression may provide promising novel therapeutic tools. Finally, we give future directions for the field's progress in disentangling the connection between genes, environment, and behavior.

Understanding the genetics and neurobiological pathways behind addiction (Review)

The hypothesis issued by modern medicine states that many diseases known to humans are genetically determined, influenced or not by environmental factors, which is applicable to most psychiatric disorders as well. This article focuses on two pending questions regarding addiction: Why do some individuals become addicted while others do not? along with Is it a learned behavior or is it genetically predefined? Recent data suggest that addiction is more than repeated exposure, it is the synchronicity between intrinsic factors (genotype, sex, age, preexisting addictive disorder, or other mental illness), extrinsic factors (childhood, level of education, socioeconomic status, social support, entourage, drug availability) and the nature of the addictive agent (pharmacokinetics, path of administration, psychoactive properties). The dopamine-mesolimbic motivation-reward-reinforcement cycle remains the most coherent physiological theory in addiction. While the common property of addictive substances is that they are dopamine-agonists, each class has individual mechanisms, pharmacokinetics and psychoactive potentials.

A Novel Precision Approach to Overcome the "Addiction Pandemic" by Incorporating Genetic Addiction Risk Severity (GARS) and Dopamine Homeostasis Restoration

This article describes a unique therapeutic precision intervention, a formulation of enkephalinase inhibitors, enkephalin, and dopamine-releasing neuronutrients, to induce dopamine homeostasis for detoxification and treatment of individuals genetically predisposed to developing reward deficiency syndrome (RDS). The formulations are based on the results of the addiction risk severity (GARS) test. Based on both neurogenetic and epigenetic evidence, the test evaluates the presence of reward genes and risk alleles. Existing evidence demonstrates that the novel genetic risk testing system can successfully stratify the potential for developing opioid use disorder (OUD) related risks or before initiating opioid analgesic therapy and RDS risk for people in recovery. In the case of opioid use disorders, long-term maintenance agonist treatments like methadone and buprenorphine may create RDS, or RDS may have been in existence, but not recognized. The test will also assess the potential for benefit from medication-assisted treatment with dopamine augmentation. RDS methodology holds a strong promise for reducing the burden of addictive disorders for individuals, their families, and society as a whole by guiding the restoration of dopamine homeostasisthrough anti-reward allostatic neuroadaptations. WC 175.

Recent Advances in the Treatment of Opioid Use Disorder

PURPOSE OF REVIEW

Opioid use disorder (OUD) remains a national epidemic with an immense consequence to the United States' healthcare system. Current therapeutic options are limited by adverse effects and limited efficacy.

RECENT FINDINGS

Recent advances in therapeutic options for OUD have shown promise in the fight against this ongoing health crisis. Modifications to approved medication-assisted treatment (MAT) include office-based methadone maintenance, implantable and monthly injectable buprenorphine, and an extended-release injectable naltrexone. Therapies under investigation include various strategies such as heroin vaccines, gene-targeted therapy, and biased agonism at the G protein-coupled receptor (GPCR), but several pharmacologic, clinical, and practical barriers limit these treatments' market viability. This manuscript provides a comprehensive review of the current literature regarding recent innovations in OUD treatment.

Bulleyaconitine A Inhibits Morphine-Induced Withdrawal Symptoms, Conditioned Place Preference, and Locomotor Sensitization Via Microglial Dynorphin A Expression

Bulleyaconitine A (BAA), a C19-diterpenoid alkaloid, has been prescribed as a nonnarcotic analgesic to treat chronic pain over four decades in China. The present study investigated its inhibition in morphine-induced withdrawal symptoms, conditioned place preference (CPP) and locomotor sensitization, and then explored the underlying mechanisms of actions. Multiple daily injections of morphine but not BAA up to 300 μg/kg/day into mice evoked naloxone-induced withdrawal symptoms (i.e., shakes, jumps, genital licks, fecal excretion and body weight loss), CPP expression, and locomotor sensitization. Single subcutaneous BAA injection (30–300 μg/kg) dose-dependently and completely attenuated morphine-induced withdrawal symptoms, with ED₅₀ values of 74.4 and 105.8 μg/kg in shakes and body weight loss, respectively. Subcutaneous BAA (300 μg/kg) also totally alleviated morphine-induced CPP acquisition and expression and locomotor sensitization. Furthermore, subcutaneous BAA injection also specifically stimulated dynorphin A expression in microglia but not astrocytes or neurons in nucleus accumbens (NAc) and hippocampal, measured for gene and protein expression and double immunofluorescence staining. In addition, subcutaneous BAA-inhibited morphine-induced withdrawal symptoms and CPP expression were totally blocked by the microglial metabolic inhibitor minocycline, dynorphin A antiserum, or specific KOR antagonist GNTI, given intracerebroventricularly. These results, for the first time, illustrate that BAA attenuates morphine-induced withdrawal symptoms, CPP expression, and locomotor sensitization by stimulation of microglial dynorphin A expression in the brain, suggesting that BAA may be a potential candidate for treatment of opioids-induced physical dependence and addiction.

Identification of a sex-stratified genetic algorithm for opioid addiction risk

The opioid epidemic has had a devastating impact on our country, with wide-ranging effects on healthcare, corrections, employment, and social systems. Programs have been put in place for monitoring prescriptions, initiating and expanding medications for opioid use disorder, and harm reduction (i.e., naloxone distribution, needle exchanges). However, opportunities for personalization of opioid therapy based on addiction risk have been limited. The goal of the present study was to develop an objective risk assessment algorithm based on genetic markers that are correlated with opioid use disorder (OUD). A total of 180 single-nucleotide polymorphisms (SNPs) were tested in patients with and without OUD. SNPs selected for testing were associated with opioid metabolism and drug reward pathways based on previous studies. Of the 394 patients recruited, 200 had OUD and 194 served as controls without OUD but with prior opioid exposure. Logistic regression analyses stratified by sex identified ten unique SNPs in females and nine unique SNPs in males that were significantly associated with OUD. A Genetics Opioid Risk Score (GenORs) was calculated by counting the number of OUD risk-associated SNPs/genotypes for each patient. To evaluate the discrimination of the GenORs, a receiver operating characteristic (ROC) curve for each sex was generated and determined to be sensitive and specific. This represents the first published example of a sex-based genetic risk score with potential to predict OUD, and the first OUD algorithm to include opioid-associated pharmacokinetic genes.

Impulsivity in heroin-dependent individuals: structural and functional abnormalities within frontostriatal circuits

High levels of impulsivity are a risk factor for the initiation of heroin use and a core behavioral characteristic of heroin dependence. Impulsivity also contributes to the maintenance of drug use and hinders effective therapy. Here we sought to identify neuroimaging markers of impulsivity in heroin-dependent individuals (HDI), with a focus on the nucleus accumbens (NAc), a key region implicated in impulsivity and drug addiction generally. Volume and resting-state functional connectivity (RSFC) differences of the bilateral NAc were investigated between 21 HDI and 21 age-, gender-, nicotine-, alcohol-matched healthy controls (HC). The neuroimaging results were then correlated with the Barratt Impulsivity Scales (BIS-11). Higher motor impulsivity (t = 2.347, p = 0.0253) and larger right NAc volume (F (1,38) = 4.719, p = 0.036) was observed in HDI. The right NAc volume was positively correlated with BIS total (r = 0.6196, p = 0.0239) /motor (r = 0.5921, p = 0.0330) scores in HC and BIS motor (r = 0.5145, p = 0.0170) score in HDI. A negative correlation was found between RSFC of the right NAc-bilateral superior frontal gyrus (SFG) and motor impulsivity in HDI (left: r=-0.6537, p = 0.0013; right: r=-0.6167, p = 0.0029) and HC (left: r=-0.6490,p = 0.0164; right: r=-0.6993, p = 0.0078). We aimed to reveal novel multimodality neuroimaging biomarkers of the higher impulsivity in HDI by focusing on the NAc and corresponding functional circuits. Higher motor impulsivity was observed in HDI. Furthermore, the volume of the right NAc and the RSFC strength of right NAc-SFG could be neuroimaging biomarkers for the severity of impulsivity in HDI. These potential biomarkers could be a target for novel treatments in HDI.

Genetic susceptibility of opioid receptor genes polymorphism to drug addiction: A candidate-gene association study

BACKGROUND

Like other complex diseases including drug addiction, genetic factors can interfere with the disease. In this study, three opioid genes (OPRM1, OPRD1, and OPRK1) were examined for an association with drug addiction among Jordanian males.

METHODS

The study involved 498 addicts, in addition to 496 healthy controls and all from Arab descent.

RESULTS

The findings in this study showed that rs1799971 of the OPRM1 gene was in association with drug addiction for both alleles and genotypes with P-values = 0.002 and 0.01, respectively. In addition, a significant association between the dominant model (A/A vs G/A-G/G) of rs1799971 (OPRM1) and drug addiction (P-value = 0.003, OR = 1.59 (1.17-2.15)) was detected. Moreover, a genetic haplotype (AGGGCGACCCC) of theOPRM1 gene revealed a significant association with drug addiction (P-value = 0.01, OR = 1.56 (1.15-2.12)). We also found that the age of addicts, smoking, and marital status with genetic variants within OPRM1, OPRD1, and OPRK1 genes may be implicated in drug addiction risk.

CONCLUSION

We propose that rs1799971 of the OPRM1gene is a genetic risk factor for drug addiction among Jordanian males.

How to Measure Pain

PURPOSE OF REVIEW

Pain is a multi-faceted symptom. Effective pain assessment involves properly defining the pain syndrome, utilizing various assessment tools, and recognizing different conditions which may affect the expression and the management of pain.

RECENT FINDINGS

Pain results from multiple physical and psychosocial etiological interplay. It has traditionally been categorized as acute or chronic with chronic pain having been categorized further into 6 categories in ICD 11. At the same time, the opioid epidemic and the recent surge in cannabis popularity further complicates pain assessment and effective pain management. Adequate management of pain begins with proper assessment including conducting extensive medical and psychosocial history and physical examination, and utilizing various pain and substance risk assessment tools. An interdisciplinary team approach may be more effective in managing complex pain behaviors compared to a solo approach.

First Report of Pharmacogenomic Profiling in an Outpatient Spine Setting: Preliminary Results from a Pilot Study

OBJECTIVE

Pharmacogenomics may help personalize medicine and improve therapeutic selection. This is the first study investigating how pharmacogenomic testing may inform analgesic selection in patients with spine disease. We profile pharmacogenetic differences in pain medication-metabolizing enzymes across patients presenting at an outpatient spine clinic and provide preliminary evidence that genetic polymorphisms may help explain interpatient differences in preoperative pain refractory to conservative management.

METHODS

Adults presenting to our outpatient spine clinic with chief symptoms of neck and/or back pain were prospectively enrolled over 9 months. Patients completed the Wong-Baker FACES and numeric pain rating scales for their chief pain symptom and provided detailed medication histories and cheek swab samples for genomic analysis.

RESULTS

Thirty adults were included (mean age, 60.6 ± 15.3 years). The chief concern was neck pain in 23%, back pain in 67%, and combined neck/back pain in 10%. At enrollment, patient analgesic regimens comprised 3 ± 1 unique medications, including 1 ± 1 opioids. After genomic analysis, 14/30 patients (47%) were identified as suboptimal metabolizers of ≥1 medications in their analgesic regimen. Of these patients, 93% were suboptimal metabolizers of their prescribed opioid analgesic. Nonetheless, pain scores were similar between optimal and suboptimal metabolizer groups.

CONCLUSIONS

This pilot study shows that a large proportion of the spine outpatient population may use pain medications for which they are suboptimal metabolizers. Further studies should assess whether these pharmacogenomic differences indicate differences in odds of receiving therapeutic benefit from surgery or if they can be used to generate more effective postoperative analgesic regimens.

Alcohol Addiction, Gut Microbiota, and Alcoholism Treatment: A Review

Alcohol addiction is a leading risk factor for personal death and disability. In 2016, alcohol use caused 2.2% of female deaths and 6.8% of male deaths, and disability-adjusted life years (DALYs) were 2.3% in female and 8.9% in male. Individuals with alcohol use disorder are at high risk of anxiety, depression, impaired cognition performance, and illicit drug use and are comorbid with liver disease, such as alcoholic hepatitis and liver cirrhosis, which is a major cause of personal death and disability worldwide. Psychological interventions, such as cognitive behavior therapy and motivational interviewing, as well as medical treatments, such as disulfiram, naltrexone, acamprosate, and nalmefene, are used for the treatment of alcohol addiction in Europe and the United States. However, the effect of current interventions is limited, and the need for additional interventions is substantial. Alcohol use impairs the intestinal barrier and causes changes to the intestinal permeability as well as the gut microbiota composition. Emerging studies have tried to reveal the role of the gut–brain axis among individuals with alcohol use disorder with or without alcohol liver disease. Bacterial products penetrate the impaired intestinal barrier and cause central inflammation; changes to the gut microbiota impair enterohepatic circulation of bile acids; alcohol abuse causes shortage of vital nutrients such as thiamine. Several studies have suggested that probiotics, through either oral administration or fecal microbiota transplantation, increased intestinal levels of potentially beneficial bacteria such as bifidobacteria and lactobacilli, improving the levels of liver-associated enzymes in patients with mild alcoholic hepatitis, and demonstrating beneficial psychotropic effects on anxiety and depression. In addition to medications for alcohol addiction, gene editing therapy such as clustered regularly interspaced short palindromic repeats (CRISPRs) may be another potential research target. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which are associated with ADH and ALDH genes, are major enzymes involved in alcohol metabolism, and gene editing approaches may have the potential to directly modify specific genes to treat alcoholism caused by genetic defects. Further research is needed to study the effect of the combined treatment for alcohol addiction.