Epigenetic Alterations in Prescription Opioid Misuse: New Strategies for Precision Pain Management

Epigenetic and sex differences in opioid use disorder in chronic pain: A real-world study linked with OPRM1 DNA methylation

Opioid use disorder (OUD) is a multifaceted condition influenced by sex, genetic and environmental factors that could be linked with epigenetic changes. Understanding how these factors interact is crucial to understand and address the development and progression of this disorder. Our aim was to elucidate different potential epigenetic and genetic mechanisms between women and men that correlate with OUD under real-world pain unit conditions. Associations between analgesic response and the DNA methylation level of the opioid mu receptor (OPRM1) gene (CpG sites 1-5 selected in the promoter region) were evaluated in 345 long opioid-treated chronic non cancer pain: cases with OUD (n = 67) and controls (without OUD, n = 278). Cases showed younger ages, low employment status and quality of life, but higher morphine equivalent daily dose and psychotropic use, compared to the controls. The patients with OUD showed a significant decrease in OPRM1 DNA methylation, which correlated with clinical outcomes like pain relief, depression and different adverse events. Significant differences were found at the five CpG sites studied for men, and exclusively in women for CpG site 3, in relation to OUD diagnosis. These findings support the importance of epigenetics and sex as biological variables to be considered toward efficient OUD understanding and therapy development.

Opioids and opioid receptors; understanding pharmacological mechanisms as a key to therapeutic advances and mitigation of the misuse crisis

Opioids are a mainstay in acute pain management and produce their effects and side effects (e.g., tolerance, opioid-use disorder and immune suppression) by interaction with opioid receptors. I will discuss opioid pharmacology in some controversial areas of enquiry of anaesthetic relevance. The main opioid target is the µ (mu,MOP) receptor but other members of the opioid receptor family, δ (delta; DOP) and κ (kappa; KOP) opioid receptors also produce analgesic actions. These are naloxone-sensitive. There is important clinical development relating to the Nociceptin/Orphanin FQ (NOP) receptor, an opioid receptor that is not naloxone-sensitive. Better understanding of the drivers for opioid effects and side effects may facilitate separation of side effects and production of safer drugs. Opioids bind to the receptor orthosteric site to produce their effects and can engage monomer or homo-, heterodimer receptors. Some ligands can drive one intracellular pathway over another. This is the basis of biased agonism (or functional selectivity). Opioid actions at the orthosteric site can be modulated allosterically and positive allosteric modulators that enhance opioid action are in development. As well as targeting ligand-receptor interaction and transduction, modulating receptor expression and hence function is also tractable. There is evidence for epigenetic associations with different types of pain and also substance misuse. As long as the opioid narrative is defined by the 'opioid crisis' the drive to remove them could gather pace. This will deny use where they are effective, and access to morphine for pain relief in low income countries.

Early life adversity: Epigenetic regulation underlying drug addiction susceptibility

Drug addiction is a leading cause of disability worldwide, with more than 70,000 Americans dying from drug overdose in 2019 alone. While only a small percentage of chronic drug users escalate to drug addiction, little is understood on the precise mechanisms of this susceptibility. Early life adversity is causally relevant to adult psychiatric disease and may contribute to the risk of addiction. Here we review recent pre-clinical evidence showing that early life exposure to stress and/or drugs regulates changes in behavior, gene expression, and the epigenome that persist into adulthood. We summarize the major findings and gaps in the preclinical literature, highlighting studies that demonstrate the often profound differences between female and male subjects.

Effect of Fu's subcutaneous needling for cancer pain management: protocol for a pragmatic randomised controlled trial

INTRODUCTION

Pain is a common symptom in patients with cancer, and pain management is crucial for these patients. Fu's subcutaneous needling (FSN) is a modern acupuncture therapy based on basic medicine commonly used in patients with pain. However, evidence of its effectiveness in treating cancer pain has not been systematically proven. Therefore, this pragmatic randomised controlled trial aims to evaluate the effectiveness and safety of FSN for cancer pain management.

METHODS AND ANALYSIS

Overall, 120 eligible patients will be recruited and randomly assigned into two groups using block randomisation. Both groups will be administered analgesic drugs according to the National Comprehensive Cancer Network guidelines. The treatment group will receive FSN therapy one time a day for 6 days. Additionally, we will assess analgesic consumption as the primary outcome and the Numerical Rating Scale, outbreak pain, symptom assessment and adverse events as secondary outcomes to evaluate the effect and safety of FSN in treating cancer pain. The incidence of adverse events will be monitored to assess the safety of FSN.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Ethics Committee of the First Affiliated Hospital of Guangzhou University of Chinese Medicine (approval No: K(2021)096). The results will be published in a peer-reviewed journal, and trial participants will be informed via email and/or phone calls.

TRIAL REGISTRATION NUMBER

ChiCTR2200056348.

The association of chronic pain and opioid withdrawal in men and women with opioid use disorder

BACKGROUND

Approximately 2.7 million individuals in the United States had an opioid use disorder (OUD) in 2020. Chronic pain may exacerbate opioid withdrawal severity, yet most research on opioid withdrawal has not collected data on chronic pain status. Moreover, there is limited evidence that women tend to experience greater opioid withdrawal severity than men, but large, confirmatory studies on this topic have not been published. The goal of this study was to examine the roles of chronic pain and gender on opioid withdrawal severity using a large, multi-site database.

METHODS

Data were collected from N = 1252 individuals with OUD entering eight residential addiction treatment facilities. Demographic, drug use behaviors, and chronic pain status were collected at treatment intake, and self-reported opioid withdrawal and craving were measured at intake and 1-3 days, 4-6 days, and 7-9 days after intake. Regression analyses were used to predict withdrawal and craving severity at intake and across the four timepoints.

RESULTS

At intake, withdrawal was higher in persons who were older, had greater SUD severity, women, had chronic pain, and used > 1 substance (p-values ≤.007) and craving was higher in persons with greater SUD severity (p < .001) and women (p = .033). Withdrawal remained higher in women and persons with chronic pain across timepoints but decreased at a similar rate relative to comparators.

CONCLUSIONS

Women and persons with chronic pain would benefit from earlier engagement in treatment and may require a more intensive strategy to mitigate opioid withdrawal in early treatment.