Oxycodone’s Unparalleled Addictive Potential: Is it Time for a Moratorium?

The association between polypharmacy and health-related quality of life among older adults with prostate cancer

INTRODUCTION

Older adults with prostate cancer (PC) are at risk of polypharmacy, which further complicates disease management and health-related quality of life (HRQoL). This study evaluated the association between polypharmacy and HRQoL among Medicare beneficiaries with PC.

MATERIALS AND METHODS

This observational, retrospective study analyzed data from the Surveillance, Epidemiology, and End Results (SEER) Medicare Health Outcomes Survey (MHOS) data resource. Beneficiaries aged ≥65 and enrolled in Medicare Advantage Organizations were included if they had a PC diagnosis and continuously enrolled in Part D for 12 months prior to the completion of MHOS. Polypharmacy was determined based on the unique number of concurrent Part D prescriptions during 12 months before survey: no polypharmacy (NP, n = 0-4), polypharmacy (PP, n = 5-9), and excessive polypharmacy (EPP, n ≥ 10). HRQoL was assessed using the Physical and Mental Component Summary T-scores (PCS and MCS, respectively) in MHOS. ANOVA and Pearson's Chi-Square tests were performed to assess variances between polypharmacy and continuous/categorical variables. Multivariate linear regression models with generalized estimating equations were used to assess the association between polypharmacy and HRQoL. The severely impaired HRQoL cohort was identified based on normalized z-scores of PCS and MCS. Odds ratios were calculated to prioritize drug-drug and class-class pairs associated with patients with severely impaired HRQoL.

RESULTS

Data from 16,573 beneficiaries (24,126 records) showed that 44.4% had PP and 10.1% had EPP. Beneficiaries with PP and EPP had significantly lower mean PCS and MCS scores compared to those without polypharmacy (p < 0.001). After adjusting for covariates, beneficiaries with EPP had clinically significantly lower PCS (adjusted marginal difference: -8.47 [-9.00, -7.94]) and MCS (adjusted marginal difference: -4.32 [-4.89, -3.75]) compared to the NP group. Top-ranked drug-drug pairs like tiotropium bromide and oxycodone/acetaminophen exhibited significant associations with HRQoL decline. Analysis of class-class pairs highlighted (1) corticosteroid hormone receptor agonists and opioid agonists and (2) benzodiazepines and adrenergic beta2-agonists as having significant associations with HRQoL decline.

DISCUSSION

Polypharmacy exhibits a significant association with HRQoL declines among older adults with PC.

State-level variation in distribution of oxycodone and opioid-related deaths from 2000 to 2021: an ecological study of ARCOS and CDC WONDER data in the USA

OBJECTIVES

This study aims to characterise oxycodone's distribution and opioid-related overdoses in the USA by state from 2000 to 2021.

DESIGN

This is an observational study.

SETTING

More than 80 000 Americans died of an opioid overdose in 2021 as the USA continues to struggle with an opioid crisis. Prescription opioids play a substantial role, introducing patients to opioids and providing a supply of drugs that can be redirected to those seeking to misuse them.

METHODS

The Drug Enforcement Administration annual summary reports from the Automation of Reports and Consolidated Orders System provided weights of oxycodone distributed per state by business type (pharmacies, hospitals and practitioners). Weights were converted to morphine milligram equivalents (MME) per capita and normalised for population. The Centers for Disease Control and Prevention Wide-ranging ONline Data for Epidemiologic Research provided mortality data for heroin, other opioids, methadone, other synthetic narcotics and other/unspecified narcotics.

RESULTS

There was a sharp 280.13% increase in total MME/person of oxycodone from 2000 to 2010, followed by a slower 54.34% decrease from 2010 to 2021. Florida (2007-2011), Delaware (2003-2020) and Tennessee (2012-2021) displayed consistent and substantial elevations in combined MME/person compared with other states. In the peak year (2010), there was a 15-fold difference between the highest and lowest states. MME/person from only pharmacies, which constituted >94% of the total, showed similar results. Hospitals in Alaska (2000-2001, 2008, 2010-2021), Colorado (2008-2021) and DC (2000-2011) distributed substantially more MME/person over many years compared with other states. Florida stood out in practitioner-distributed oxycodone, with an elevation of almost 15-fold the average state from 2006 to 2010. Opioid-related deaths increased +806% from 2000 to 2021, largely driven by heroin, other opioids and other synthetic narcotics.

CONCLUSIONS

Oxycodone distribution across the USA showed marked differences between states and business types over time. Investigation of opioid policies in states of interest may provide insight for future actions to mitigate opioid misuse.

Trends in oxycodone and oxycodone-containing analgesics administration for back pain in emergency departments in the USA (2007-2018)

BACKGROUND

To describe trends in oxycodone and oxycodone-containing analgesic prescribing for the treatment of back pain among adults in emergency departments (EDs) in the USA from 2007 to 2018.

METHODS

Data were gathered from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2007 to 2018. The study population included individuals of all ages presenting to USA EDs. The NHAMCS reasons for visit and oxycodone drug ID codes were used to isolate patients with back pain. The main outcome was the proportion of oxycodone and oxycodone-containing analgesics prescribed for back pain in the EDs over the specified time period.

RESULTS

There was a relative decrease in the overall administration of oxycodone for back pain in the EDs by 62.3% from 2007 (244,000 visits) to 2018 (92,000 visits). The proportion of ED patients prescribed with oxycodone-containing analgesics for back pain increased among patients aged 45 years and older (from 43.8% to 57.6%), female patients (from 54.5% to 62.0%), black patients (from 22.5% to 30.4%), and Hispanic/Latino patients (from 9.4% to 19.6%). Oxycodone/acetaminophen was most prescribed and accounted for 90.2% of all oxycodone-containing analgesics in 2007, with a decrease to 68.5% in 2018. Pure oxycodone was the second most prescribed medication, accounting for 6.1% in 2007 and 31.5% in 2018.

CONCLUSION

The overall number of oxycodone-containing analgesics decreased significantly from 2007 to 2018. However, that number trended upward in 45-year-old and older, female, black, or Hispanic/Latino patients from 2007 to 2018. The total amount of pure oxycodone increased significantly from 2007 to 2008.

Oxycodone, an opioid like the others?

The over-prescription of opioid analgesics is a growing problem in the field of addiction, which has reached epidemic-like proportions in North America. Over the past decade, oxycodone has gained attention as the leading opioid responsible for the North America opioid crisis. Oxycodone is the most incriminated drug in the early years of the epidemic of opioid use disorder in USA (roughly 1999-2016). The number of preclinical articles on oxycodone is rapidly increasing. Several publications have already compared oxycodone with other opioids, focusing mainly on their analgesic properties. The aim of this review is to focus on the genomic and epigenetic regulatory features of oxycodone compared with other opioid agonists. Our aim is to initiate a discussion of perceptible differences in the pharmacological response observed with these various opioids, particularly after repeated administration in preclinical models commonly used to study drug dependence potential.

Oxycodone: A Current Perspective on Its Pharmacology, Abuse, and Pharmacotherapeutic Developments

Oxycodone, a semisynthetic derivative of naturally occurring thebaine, an opioid alkaloid, has been available for more than 100 years. Although thebaine cannot be used therapeutically due to the occurrence of convulsions at higher doses, it has been converted to a number of other widely used compounds that include naloxone, naltrexone, buprenorphine, and oxycodone. Despite the early identification of oxycodone, it was not until the 1990s that clinical studies began to explore its analgesic efficacy. These studies were followed by the pursuit of several preclinical studies to examine the analgesic effects and abuse liability of oxycodone in laboratory animals and the subjective effects in human volunteers. For a number of years oxycodone was at the forefront of the opioid crisis, playing a significant role in contributing to opioid misuse and abuse, with suggestions that it led to transitioning to other opioids. Several concerns were expressed as early as the 1940s that oxycodone had significant abuse potential similar to heroin and morphine. Both animal and human abuse liability studies have confirmed, and in some cases amplified, these early warnings. Despite sharing a similar structure with morphine and pharmacological actions also mediated by the μ-opioid receptor, there are several differences in the pharmacology and neurobiology of oxycodone. The data that have emerged from the many efforts to analyze the pharmacological and molecular mechanism of oxycodone have generated considerable insight into its many actions, reviewed here, which, in turn, have provided new information on opioid receptor pharmacology. SIGNIFICANCE STATEMENT: Oxycodone, a μ-opioid receptor agonist, was synthesized in 1916 and introduced into clinical use in Germany in 1917. It has been studied extensively as a therapeutic analgesic for acute and chronic neuropathic pain as an alternative to morphine. Oxycodone emerged as a drug with widespread abuse. This article brings together an integrated, detailed review of the pharmacology of oxycodone, preclinical and clinical studies of pain and abuse, and recent advances to identify potential opioid analgesics without abuse liability.

Postoperative Opioid Consumption Following Hallux Valgus and Rigidus Surgery: A Guide to Postoperative Prescription Writing

Prescribing postoperative pain medications is essential to foot and ankle surgery; however, prescribing an amount that results in an excess of pills has shown to lead to opioid abuse. The opioid epidemic has forced surgeons to analyze how we manage postoperative pain with a goal to prescribe the optimal number of pills that will reduce a patient's pain while limiting the amount that is left over. The purpose of this study was to develop a guideline for prescribing postoperative pain medication for hallux valgus and rigidus procedures. One hundred eighty-five opioid naive patients were followed after undergoing surgery for hallux valgus or hallux rigidus. The number of opioids consumed was obtained and compared to a number of variables. There were 28 different prescriptions given during the study. As the number of pills given decreased, so did the number of pills consumed (p = .08). Of the 185 patients, 14 (7.56%) received a refill. Ninety-five patients were available for opioid consumption data analysis. Those patients consumed a median of 36.7% and 39.1% of their prescription for hallux valgus and hallux rigidus procedures respectively. Smokers consumed 2.4 times the number of narcotics compared to nonsmokers (p = .002). The median number of 5-325 mg hydrocodone-acetaminophen pills consumed was 8.5 for distal metatarsal osteotomies and 10 for first metatarsophalangeal joint procedures. Body mass index, gender, number of procedures performed did not have a statistical difference in the number of opioids taken. Foot and ankle surgeons can reduce the amount of excess opioids by decreasing the initial prescription and educating the patient on proper pain management modalities.

Effects of sex and estrous cycle on intravenous oxycodone self-administration and the reinstatement of oxycodone-seeking behavior in rats

Introduction

The increasing misuse of both prescription and illicit opioids has culminated in a national healthcare crisis in the United States. Oxycodone is among the most widely prescribed and misused opioid pain relievers and has been associated with a high risk for transition to compulsive opioid use. Here, we sought to examine potential sex differences and estrous cycle-dependent effects on the reinforcing efficacy of oxycodone, as well as on stress-induced or cue-induced oxycodone-seeking behavior, using intravenous (IV) oxycodone self-administration and reinstatement procedures.

Methods

In experiment 1, adult male and female Long-Evans rats were trained to self-administer 0.03 mg/kg/inf oxycodone according to a fixed-ratio 1 schedule of reinforcement in daily 2-h sessions, and a dose-response function was subsequently determined (0.003-0.03 mg/kg/inf). In experiment 2, a separate group of adult male and female Long-Evans rats were trained to self-administer 0.03 mg/kg/inf oxycodone for 8 sessions, followed by 0.01 mg/kg/inf oxycodone for 10 sessions. Responding was then extinguished, followed by sequential footshock-induced and cue-induced reinstatement tests.

Results

In the dose-response experiment, oxycodone produced a typical inverted U-shape function with 0.01 mg/kg/inf representing the maximally effective dose in both sexes. No sex differences were detected in the reinforcing efficacy of oxycodone. In the second experiment, the reinforcing effects of 0.01-0.03 mg//kg/inf oxycodone were significantly attenuated in females during proestrus/estrus as compared to metestrus/diestrus phases of the estrous cycle. Neither males nor females displayed significant footshock-induced reinstatement of oxycodone seeking, but both sexes exhibited significant cue-induced reinstatement of oxycodone seeking at magnitudes that did not differ either by sex or by estrous cycle phase.

Discussion

These results confirm and extend previous work suggesting that sex does not robustly influence the primary reinforcing effects of oxycodone nor the reinstatement of oxycodone-seeking behavior. However, our findings reveal for the first time that the reinforcing efficacy of IV oxycodone varies across the estrous cycle in female rats.

Effects of sex and estrous cycle on intravenous oxycodone self-administration and the reinstatement of oxycodone-seeking behavior in rats

The increasing misuse of both prescription and illicit opioids has culminated in a national healthcare crisis in the United States. Oxycodone is among the most widely prescribed and misused opioid pain relievers and has been associated with a high risk for transition to compulsive opioid use. Here, we sought to examine potential sex differences and estrous cycle-dependent effects on the reinforcing efficacy of oxycodone, as well as on stress-induced or cue-induced oxycodone-seeking behavior, using intravenous (IV) oxycodone self-administration and reinstatement procedures. In experiment 1, adult male and female Long-Evans rats were trained to self-administer 0.03 mg/kg/inf oxycodone according to a fixed-ratio 1 schedule of reinforcement in daily 2-hr sessions, and a dose-response function was subsequently determined (0.003-0.03 mg/kg/inf). In experiment 2, a separate group of adult male and female Long-Evans rats were trained to self-administer 0.03 mg/kg/inf oxycodone for 8 sessions, followed by 0.01 mg/kg/inf oxycodone for 10 sessions. Responding was then extinguished, followed by sequential footshock-induced and cue-induced reinstatement tests. In the dose-response experiment, oxycodone produced a typical inverted U-shape function with 0.01 mg/kg/inf representing the maximally effective dose in both sexes. No sex differences were detected in the reinforcing efficacy of oxycodone. In the second experiment, the reinforcing effects of 0.01-0.03 mg//kg/inf oxycodone were significantly attenuated in females during proestrus/estrus as compared to metestrus/diestrus phases of the estrous cycle. Neither males nor females displayed significant footshock-induced reinstatement of oxycodone seeking, but both sexes exhibited significant cue-induced reinstatement of oxycodone seeking at magnitudes that did not differ either by sex or by estrous cycle phase. These results confirm and extend previous work suggesting that sex does not robustly influence the primary reinforcing effects of oxycodone nor the reinstatement of oxycodone-seeking behavior. However, our findings reveal for the first time that the reinforcing efficacy of IV oxycodone varies across the estrous cycle in female rats.

Oral Oxycodone-Induced Respiratory Depression during Normocapnia and Hypercapnia: A Pharmacokinetic-Pharmacodynamic Modeling Study

The widely prescribed opioid oxycodone may cause lethal respiratory depression. We compared the effects of oxycodone on breathing and antinociception in healthy young volunteers. After pharmacokinetic/pharmacodynamic (PK/PD) modeling, we constructed utility functions to combine the wanted and unwanted end points into a single function. We hypothesized that the function would be predominantly negative over the tested oxycodone concentration range. Twenty-four male and female volunteers received 20 (n = 12) or 40 (n = 12) mg oral oxycodone immediate-release tablets. Hypercapnic ventilatory responses (visit 1) or responses to 3 nociceptive assays (pain pressure, electrical, and thermal tests; visit 2) were measured at regular intervals for 7 hours. the PK/PD analyses, that included carbon dioxide kinetics, stood at the basis of the utility function: probability of antinociception minus probability of respiratory depression. Oxycodone had rapid onset/offset times (30-40 minutes) with potency values (effect-site concentration causing 50% of effect) ranging from 0.05 to 0.13 ng/mL for respiratory variables obtained at hypercapnia and antinociceptive responses. Ventilation at an extrapolated end-tidal carbon dioxide partial pressure of 55 mmHg, was used for creation of 3 utility functions, one for each of the nociceptive tests. Contrary to expectation, the utility functions were close to zero or positive over the clinical oxycodone concentration range. The similar or better likelihood for antinociception relative to respiratory depression may be related to oxycodone's receptor activation profile or to is high likeability that possibly alters the modulation of nociceptive input. Oxycodone differs from other μ-opioids, such as fentanyl, that have a consistent negative utility.

Suvorexant, an FDA-approved dual orexin receptor antagonist, reduces oxycodone self-administration and conditioned reinstatement in male and female rats

Background: The Department of Health and Human Services reports that prescription pain reliever (e.g., oxycodone) misuse was initiated by 4,400 Americans each day in 2019. Amid the opioid crisis, effective strategies to prevent and treat prescription opioid use disorder (OUD) are pressing. In preclinical models, the orexin system is recruited by drugs of abuse, and blockade of orexin receptors (OX receptors) prevents drug-seeking behavior. The present study sought to determine whether repurposing suvorexant (SUV), a dual OX receptor antagonist marketed for the treatment of insomnia, can treat two features of prescription OUD: exaggerated consumption and relapse. Methods: Male and female Wistar rats were trained to self-administer oxycodone (0.15 mg/kg, i. v., 8 h/day) in the presence of a contextual/discriminative stimulus (S^D) and the ability of SUV (0-20 mg/kg, p. o.) to decrease oxycodone self-administration was tested. After self-administration testing, the rats underwent extinction training, after which we tested the ability of SUV (0 and 20 mg/kg, p. o.) to prevent reinstatement of oxycodone seeking elicited by the S^D. Results: The rats acquired oxycodone self-administration and intake was correlated with the signs of physical opioid withdrawal. Additionally, females self-administered approximately twice as much oxycodone as males. Although SUV had no overall effect on oxycodone self-administration, scrutiny of the 8-h time-course revealed that 20 mg/kg SUV decreased oxycodone self-administration during the first hour in males and females. The oxycodone S^D elicited strong reinstatement of oxycodone-seeking behavior that was significantly more robust in females. Suvorexant blocked oxycodone seeking in males and reduced it in females. Conclusions: These results support the targeting of OX receptors for the treatment for prescription OUD and repurposing SUV as pharmacotherapy for OUD.

A nationwide study on consumption of opioid analgesics in Iran from 2000 to 2018

BACKGROUND

Opioid analgesics play a unique role in pain management. National opioid consumption studies could provide indirect evidence of pain management in a country. National, regional, and global opioid consumption have been studied in other countries so far; however, conducting a focused study to illuminate the consumption of opioid analgesics over the past decades in Iran seemed necessary.

AIM

The main objective of this study was to determine the consumption of opioid analgesics and explore the trend of their use during 19 years in Iran.

METHOD

Iran pharmaceutical wholesale data were used to extract the annual consumption figures of the opioid analgesics in group N02A of the World Health Organization (WHO) Anatomical Therapeutic Chemical classification and were available in Iran (morphine, fentanyl, pethidine, and oxycodone as strong opioids and, tramadol and pentazocine as weak opioids), from 2000 to 2018. Using Defined Daily Dose (DDD) by WHO and Oral Morphine Equivalent (OMEQ), the amount of annual consumption was determined in DDD/1000 inhabitants/Day (DID) and OMEQ (mg)/1000 inhabitants/Day (OID).

RESULTS

Total opioid analgesic utilization based on DID and OID increased 31.12-fold (from 0.0196 to 0.61) and 21.06-fold (from 1.97 to 41.5 mg) over 19 years, respectively with a significant sharp increase from 2003 to 2006 (ß = 1.78 (DID), P value < 0.001). Medications that constituted 70% of annual opioid analgesics utilization were morphine in 2000, compared to tramadol in 2018. The annual weak and strong opioids share were 86.7% and 13.2% in 2018, respectively.

CONCLUSION

Despite considerable growth in the consumption of opioid analgesics in Iran over nearly two decades, the consumption amount remained low, which might signal sub-optimal pain management. On the other hand, misuse and abuse seem to be the main reason behind significant increases in the consumption of opioid analgesics with less controlled distribution.

Pharmacovigilance Signals of the Opioid Epidemic over 10 Years: Data Mining Methods in the Analysis of Pharmacovigilance Datasets Collecting Adverse Drug Reactions (ADRs) Reported to EudraVigilance (EV) and the FDA Adverse Event Reporting System (FAERS)

In the past twenty years, the consumption of opioid medications has reached significant proportions, leading to a rise in drug misuse and abuse and increased opioid dependence and related fatalities. Thus, the purpose of this study was to determine whether there are pharmacovigilance signals of abuse, misuse, and dependence and their nature for the following prescription opioids: codeine, dihydrocodeine, fentanyl, oxycodone, pentazocine, and tramadol. Both the pharmacovigilance datasets EudraVigilance (EV) and the FDA Adverse Events Reporting System (FAERS) were analyzed to identify and describe possible misuse-/abuse-/dependence-related issues. A descriptive analysis of the selected Adverse Drug Reactions (ADRs) was performed, and pharmacovigilance signal measures (i.e., reporting odds ratio, proportional reporting ratio, information component, and empirical Bayesian geometric mean) were computed for preferred terms (PTs) of abuse, misuse, dependence, and withdrawal, as well as PTs eventually related to them (e.g., aggression). From 2003 to 2018, there was an increase in ADR reports for the selected opioids in both datasets. Overall, 16,506 and 130,293 individual ADRs for the selected opioids were submitted to EV and FAERS, respectively. Compared with other opioids, abuse concerns were mostly recorded in relation to fentanyl and oxycodone, while tramadol and oxycodone were more strongly associated with drug dependence and withdrawal. Benzodiazepines, antidepressants, other opioids, antihistamines, recreational drugs (e.g., cocaine and alcohol), and several new psychoactive substances, including mitragynine and cathinones, were the most commonly reported concomitant drugs. ADRs reports in pharmacovigilance databases confirmed the availability of data on the abuse and dependence of prescription opioids and should be considered a resource for monitoring and preventing such issues. Psychiatrists and clinicians prescribing opioids should be aware of their misuse and dependence liability and effects that may accompany their use, especially together with concomitant drugs.

Non-Peptide Opioids Differ in Effects on Mu-Opioid (MOP) and Serotonin 1A (5-HT1A) Receptors Heterodimerization and Cellular Effectors (Ca2+, ERK1/2 and p38) Activation

The importance of the dynamic interplay between the opioid and the serotonin neuromodulatory systems in chronic pain is well recognized. In this study, we investigated whether these two signalling pathways can be integrated at the single-cell level via direct interactions between the mu-opioid (MOP) and the serotonin 1A (5-HT1A) receptors. Using fluorescence cross-correlation spectroscopy (FCCS), a quantitative method with single-molecule sensitivity, we characterized in live cells MOP and 5-HT1A interactions and the effects of prolonged (18 h) exposure to selected non-peptide opioids: morphine, codeine, oxycodone and fentanyl, on the extent of these interactions. The results indicate that in the plasma membrane, MOP and 5-HT1A receptors form heterodimers that are characterized with an apparent dissociation constant Kdapp = (440 ± 70) nM). Prolonged exposure to all non-peptide opioids tested facilitated MOP and 5-HT1A heterodimerization and stabilized the heterodimer complexes, albeit to a different extent: Kd, Fentanylapp = (80 ± 70) nM), Kd,Morphineapp = (200 ± 70) nM, Kd, Codeineapp = (100 ± 70) nM and Kd, Oxycodoneapp = (200 ± 70) nM. The non-peptide opioids differed also in the extent to which they affected the mitogen-activated protein kinases (MAPKs) p38 and the extracellular signal-regulated kinase (Erk1/2), with morphine, codeine and fentanyl activating both pathways, whereas oxycodone activated p38 but not ERK1/2. Acute stimulation with different non-peptide opioids differently affected the intracellular Ca2+ levels and signalling dynamics. Hypothetically, targeting MOP−5-HT1A heterodimer formation could become a new strategy to counteract opioid induced hyperalgesia and help to preserve the analgesic effects of opioids in chronic pain.

Escalated (Dependent) Oxycodone Self-Administration Is Associated with Cognitive Impairment and Transcriptional Evidence of Neurodegeneration in Human Immunodeficiency Virus (HIV) Transgenic Rats

Substance use disorder is associated with accelerated disease progression in people with human immunodeficiency virus (HIV; PWH). Problem opioid use, including high-dose opioid therapy, prescription drug misuse, and opioid abuse, is high and increasing in the PWH population. Oxycodone is a broadly prescribed opioid in both the general population and PWH. Here, we allowed HIV transgenic (Tg) rats and wildtype (WT) littermates to intravenously self-administer oxycodone under short-access (ShA) conditions, which led to moderate, stable, "recreational"-like levels of drug intake, or under long-access (LgA) conditions, which led to escalated (dependent) drug intake. HIV Tg rats with histories of oxycodone self-administration under LgA conditions exhibited significant impairment in memory performance in the novel object recognition (NOR) paradigm. RNA-sequencing expression profiling of the medial prefrontal cortex (mPFC) in HIV Tg rats that self-administered oxycodone under ShA conditions exhibited greater transcriptional evidence of inflammation than WT rats that self-administered oxycodone under the same conditions. HIV Tg rats that self-administered oxycodone under LgA conditions exhibited transcriptional evidence of an increase in neuronal injury and neurodegeneration compared with WT rats under the same conditions. Gene expression analysis indicated that glucocorticoid-dependent adaptations contributed to the gene expression effects of oxycodone self-administration. Overall, the present results indicate that a history of opioid intake promotes neuroinflammation and glucocorticoid dysregulation, and excessive opioid intake is associated with neurotoxicity and cognitive impairment in HIV Tg rats.

Pain management in the emergency department: a clinical review

Pain is one of the most common reasons for patients to visit the emergency department. The ever-growing research on emergency department analgesia has challenged the current practices with respect to the optimal analgesic regimen for acute musculoskeletal pain, safe and judicious opioid prescribing, appropriate utilization of non-opioid therapeutics, and non-pharmacological treatment modalities. This clinical review is set to provide evidence-based answers to these challenging questions.

The Association Between Preoperative Opioid Exposure and Prolonged Postoperative Use

OBJECTIVE

To determine the effect of nonchronic, periodic preoperative opioid use on prolonged opioid fills after surgery.

BACKGROUND

Nonchronic, periodic opioid use is common, but its effect on prolonged postoperative opioid fills is not well understood. We hypothesize greater periodic opioid use before surgery is correlated with persistent postoperative use.

METHODS

We used a national private insurance claims database, Optum's de-identifed Clinformatics Data Mart Database, to identify adults undergoing general, gynecologic, and urologic surgical procedures between 2008 and 2015 (N = 191,043). We described patterns of opioid fills based on dose, recency, duration, and continuity to categorize preoperative opioid exposure. Patients with chronic use were excluded. Our primary outcome was persistent postoperative use, defined as filling an opioid prescription between 91- and 180-days post-discharge. The association between preoperative opioid use and persistent use was determined using multivariable logistic regression, controlling for clinical covariates.

RESULTS

In the year before surgery, 41% of patients had nonchronic, periodic opioid fills. Compared with other risk factors, patterns of preoperative fills were most strongly correlated with persistent postoperative opioid use. Patients with recent intermittent use were significantly more likely to have prolonged fills after surgery compared with opioid-naïve patients [minimal use: odds ratio (OR): 2.0, 95% confidence interval (CI) 1.89-2.03; remote intermittent: OR 4.7, 95% CI 4.46-4.93; recent intermittent: OR 12.2, 95% CI 11.49-12.90].

CONCLUSIONS

Patients with nonchronic, periodic opioid use before surgery are vulnerable to persistent postoperative opioid use. Identifying opioid use before surgery is a critical opportunity to optimize care after surgery.

Oxytocin prevents cue-induced reinstatement of oxycodone seeking: Involvement of DNA methylation in the hippocampus

Oxycodone is one of the most commonly used analgesics in the clinic. However, long-term use can contribute to drug dependence. Accumulating evidence of changes in DNA methylation after opioid relapse has provided insight into mechanisms underlying drug-associated memory. The neuropeptide oxytocin is reported to be a potential treatment for addiction. The present study sought to identify changes in global and synaptic gene methylation after cue-induced reinstatement of oxycodone conditioned place preference (CPP) and the effect of oxytocin. We analyzed hippocampal mRNA of synaptic genes and also synaptic density in response to oxycodone CPP. We determined the mRNA levels of DNA methyltransferases (Dnmts) and ten-eleven translocations (Tets), observed global 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) levels, and measured DNA methylation status of four synaptic genes implicated in learning and memory (Arc, Dlg1, Dlg4, and Syn1). Both synaptic density and the transcription of 15 hippocampal synaptic genes significantly increased following cue-induced reinstatement of oxycodone CPP. Oxycodone relapse was also related to markedly decreased 5-mC levels and decreased transcription of Dnmt1, Dnmt3a, and Dnmt3b; in contrast, 5-hmC levels and the transcription of Tet1 and Tet3 were increased. Oxycodone exposure induced DNA hypomethylation at the exons of the Arc, Dlg1, Dlg4, and Syn1 genes. Intracerebroventricular (ICV) administration of oxytocin (2.5 μg/μl) specifically blocked oxycodone relapse, possibly by inhibition of Arc, Dlg1, Dlg4, and Syn1 hypomethylation in oxycodone-treated rats. Together, these data indicate the occurrence of epigenetic changes in the hippocampus following oxycodone relapse and the potential role of oxytocin in oxycodone addiction.

In vivo and in vitro Characterization of a Partial Mu Opioid Receptor Agonist, NKTR-181, Supports Future Therapeutic Development

Mu opioid receptor (MOPr) agonists are well-known and frequently used clinical analgesics but are also rewarding due to their highly addictive and often abusive properties. This may lead to opioid use disorder (OUD) a disorder that effects millions of people worldwide. Therefore, novel compounds are urgently needed to treat OUD. As opioids are effective analgesics and OUD often occurs in conjunction with chronic pain, these novel compounds may be opioids, but they must have a low abuse liability. This could be mediated by diminishing or slowing blood-brain barrier transport, slowing target receptor binding kinetics, and showing a long half-life. NKTR-181 is a PEGylated oxycodol and a MOPr agonist that has slowed blood-brain barrier transport, a long half-life, and diminished likeability in clinical trials. In this study, we examined the signaling and behavioral profile of NKTR-181 in comparison with oxycodone to determine whether further therapeutic development of this compound may be warranted. For this preclinical study, we used a number of in vitro and in vivo assays. The signaling profile of NKTR-181 was determined by the electrophysiological assessment of MOPr-Ca2+ channel inhibition in the nociceptive neurons of rodent dorsal root ganglia. Heterologous cell-based assays were used to assess biased agonism and receptor trafficking. Different rodent behavioral models were used to define the NKTR-181-induced relief of effective and reflexive nociception and drug-seeking behavior as assessed by an intravenous self-administration (IVSA) of NKTR-181. We found that NKTR-181 and oxycodone are partial agonists in G-protein signaling and Ca2+ channel inhibition assays and promote limited MOPr desensitization. However, NKTR-181 inhibits Ca2+ channels by a different mechanism than oxycodone and induces a different pattern of arrestin recruitment. In addition, NKTR-181 has a slower receptor on-rate and a slower rate of Ca2+ channel coupling than oxycodone. This signaling profile is coupled with a slower onset of antinociception and limited drug-seeking behavior in comparison with oxycodone. Together with its known long half-life and slow blood-brain barrier transport, these data suggest that NKTR-181 could be further studied as a pharmacotherapeutic treatment modality for OUD.

Clinical Pharmacology, Toxicity, and Abuse Potential of Opioids

Opioids were the most common drug class resulting in overdose deaths in the United States in 2019. Widespread clinical use of prescription opioids for moderate to severe pain contributed to the ongoing opioid epidemic with the subsequent emergence of fentanyl-laced heroin. More potent analogues of fentanyl and structurally diverse opioid receptor agonists such as AH-7921 and MT-45 are fueling an increasingly diverse illicit opioid supply. Overdose from synthetic opioids with high binding affinities may not respond to a typical naloxone dose, thereby rendering autoinjectors less effective, requiring higher antagonist doses or resulting in a confusing clinical picture for health care providers. Nonscheduled opioid drugs such as loperamide and dextromethorphan are associated with dependence and risk of overdose as easier access makes them attractive to opioid users. Despite a common opioid-mediated pathway, several opioids present with unique pharmacodynamic properties leading to acute toxicity and dependence development. Pharmacokinetic considerations involve half-life of the parent opioid and its metabolites as well as resulting toxicity, as is established for tramadol, codeine, and oxycodone. Pharmacokinetic considerations, toxicities, and treatment approaches for notable opioids are reviewed.

Florida State Opioid Prescription Restriction Law: Impact on Opioid Utilization After Total Joint Arthroplasty

BACKGROUND

In response to the opioid epidemic, Florida recently passed the opioid prescription limiting law, effective since July 1^st, 2018. However, its impact on opioid prescription after total joint arthroplasty (TJA) has not been elucidated. Thus, our objective was to assess if this new law led to reduced opioid prescription after TJA and to determine its impact on perioperative clinical outcomes.

METHODS

A retrospective chart review was conducted on a consecutive series of 658 primary TJAs (618 patients), performed by four surgeons in a single institution [1/2/2018-10/23/2018]. Based on effective date of the law, cases were divided into: prelaw (327 cases; 168 hips/159 knees) and postlaw (331 cases; 191 hips/140 knees) phases. Baseline demographics and surgical characteristics were compared. The effect of the law on perioperative outcomes: length of stay, complications, emergency department/office visits, patient phone calls, reoperation or readmission (90 days), and total morphine equivalents prescribed was investigated. Independent sample t-tests and chi-square analyses were performed.

RESULTS

Prelaw and postlaw phases had no significant difference in baseline demographics and characteristics. No difference was found in length of stay. Opioid law implementation led to significantly lower total oral morphine equivalents after TJAs [Prelaw: 1059.9 ± 825.4 vs postlaw: 942.8 ± 691.7; P = .04], but did not result in a significant increase in 90-day complications, patient visits (office or emergency) or phone calls, and reoperation or readmission.

CONCLUSION

Our data suggest that Florida state opioid prescription limiting law has resulted in a marked decline in opioid prescription without any increase in rates of patient visits, phone calls, or readmission after TJA.

Oxycodone in the Opioid Epidemic: High 'Liking', 'Wanting', and Abuse Liability

It is estimated that nearly a third of people who abuse drugs started with prescription opioid medicines. Approximately, 11.5 million Americans used prescription drugs recreationally in 2016, and in 2018, 46,802 Americans died as the result of an opioid overdose, including prescription opioids, heroin, and illicitly manufactured fentanyl (National Institutes on Drug Abuse (2020) Opioid Overdose Crisis. https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis . Accessed 06 June 2020). Yet physicians will continue to prescribe oral opioids for moderate-to-severe pain in the absence of alternative therapeutics, underscoring the importance in understanding how drug choice can influence detrimental outcomes. One of the opioid prescription medications that led to this crisis is oxycodone, where misuse of this drug has been rampant. Being one of the most highly prescribed opioid medications for treating moderate-to-severe pain as reflected in the skyrocketed increase in retail sales of 866% between 1997 and 2007, oxycodone was initially suggested to be less addictive than morphine. The false-claimed non-addictive formulation of oxycodone, OxyContin, further contributed to the opioid crisis. Abuse was often carried out by crushing the pills for immediate burst release, typically by nasal insufflation, or by liquefying the pills for intravenous injection. Here, we review oxycodone pharmacology and abuse liability as well as present the hypothesis that oxycodone may exhibit a unique pharmacology that contributes to its high likability and abuse susceptibility. We will discuss various mechanisms that likely contribute to the high abuse rate of oxycodone including clinical drug likability, pharmacokinetics, pharmacodynamics, differences in its actions within mesolimbic reward circuity compared to other opioids, and the possibility of differential molecular and cellular receptor interactions that contribute to its selective effects. We will also discuss marketing strategies and drug difference that likely contributes to the oxycodone opioid use disorders and addiction.

Potential for Kappa-Opioid Receptor Agonists to Engineer Nonaddictive Analgesics: A Narrative Review

A serious adverse effect of prescription opioid analgesics is addiction, both to these analgesics and to illicit drugs like heroin that also activate the µ-opioid receptor (MOR). Opioid use disorder (OUD) and opioid overdose deaths represent a current American health crisis, and the prescription of opioid analgesics has contributed significantly to this crisis. While prescription opioids are highly effective analgesics, there currently exists no facile way to use them for extended periods without the risk of addiction. If addiction caused by MOR-targeting analgesics could be blocked by blending in a new "antiaddiction" ingredient that does not diminish analgesia and does not introduce its own therapeutically limiting side effects, then continued clinical use of prescription opioids for treating pain could be maintained (or even enhanced) instead of curtailed. In this narrative review, we contextualize this hypothesis, first with a brief overview of the current American opioid addiction crisis. The neurobiology of 2 key receptors in OUD development, MOR and the κ-opioid receptor (KOR), is then discussed to highlight the neuroanatomical features and circuitry in which signal transduction from these receptors lie in opposition-creating opportunities for pharmacological intervention in curtailing the addictive potential of MOR agonism. Prior findings with mixed MOR/KOR agonists are considered before exploring new potential avenues such as biased KOR agonists. New preclinical data are highlighted, demonstrating that the G protein-biased KOR agonist nalfurafine reduces the rewarding properties of MOR-targeting analgesics and enhances MOR-targeting analgesic-induced antinociception. Finally, we discuss the recent discovery that a regulator of G protein signaling (namely, RGS12) is a key component of signaling bias at KOR, presenting another drug discovery target toward identifying a single agent or adjuvant to be added to traditional opioid analgesics that could reduce or eliminate the addictive potential of the latter drug.

Brain cell-derived exosomes in plasma serve as neurodegeneration biomarkers in male cynomolgus monkeys self-administrating oxycodone

Background

The United States is currently facing an opioid crisis. Novel tools to better comprehend dynamic molecular changes in the brain associated with the opioid abuse are limited. Recent studies have suggested the usefulness of plasma exosomes in better understanding CNS disorders. However, no study has ever characterized exosomes (small extracellular vesicles of endocytic origin) secreted by brain cells to understand the potential neurodegenerative effects of long-term oxycodone self-administration (SA).

Methods

MRI of Cynomolgus monkeys (Macaca fascicularis) was performed to assess alterations in gray matter volumes with oxycodone SA. We isolated total exosomes (TE) from the plasma of these monkeys; from TE, we pulled-out neuron-derived exosomes (NDE), astrocytes-derived exosomes (ADE), and microglia-derived exosomes (MDE) using surface biomarkers L1CAM (L1 cell adhesion molecule), GLAST (Glutamate aspartate transporter) and TMEM119 (transmembrane protein119), respectively.

Findings

We observed a significantly lower gray matter volume of specific lobes of the brain (frontal and parietal lobes, and right putamen) in monkeys with ∼3 years of oxycodone SA compared to controls. Higher expression of neurodegenerative biomarkers (NFL and α-synuclein) correlates well with the change in brain lobe volumes in control and oxycodone SA monkeys. We also identified a strong effect of oxycodone SA on the loading of specific miRNAs and proteins associated with neuro-cognitive disorders. Finally, exosomes subpopulation from oxycodone SA group activated NF-κB activity in THP1- cells.

Interpretation

These results provide evidence for the utility of brain cells-derived exosomes from plasma in better understanding and predicting the pro-inflammatory and neurodegenerative consequence of oxycodone SA.

Funding

NIH

The molecular neurobiology and neuropathology of opioid use disorder

The number of people diagnosed with opioid use disorder has skyrocketed as a consequence of the opioid epidemic and the increased prescribing of opioid drugs for chronic pain relief. Opioid use disorder is characterized by loss of control of drug taking, continued drug use in the presence of adverse consequences, and repeated relapses to drug taking even after long periods of abstinence. Patients who suffer from opioid use disorder often present with cognitive deficits that are potentially secondary to structural brain abnormalities that vary according to the chemical composition of the abused opioid. This review details the neurobiological effects of oxycodone, morphine, heroin, methadone, and fentanyl on brain neurocircuitries by presenting the acute and chronic effects of these drugs on the human brain. In addition, we review results of neuroimaging in opioid use disorder patients and/or histological studies from brains of patients who had expired after acute intoxication following long-term use of these drugs. Moreover, we include relevant discussions of the neurobiological mechanisms involved in promoting abnormalities in the brains of opioid-exposed patients. Finally, we discuss how novel strategies could be used to provide pharmacological treatment against opioid use disorder.

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Brain abnormalities caused by opioid intoxication.

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Intoxication of opioids leads to defects in brain neurocircuitries.

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Insight into the molecular mechanisms associated with craving in heroin addicts.

Prescription and Prescriber Specialty Characteristics of Initial Opioid Prescriptions Associated with Chronic Use

OBJECTIVE

This study evaluated the characteristics of opioid prescriptions, including prescriber specialty, given to opioid-naïve patients and their association with chronic use.

DESIGN

Cross-sectional analysis of the Ohio prescription drug monitoring program from January 2010 to November 2017.

SETTING

Ohio, USA.

SUBJECTS

Patients who had no opioid prescriptions from 2010 to 2012 and a first-time prescription from January 2013 to November 2016.

METHODS

Chronic use was defined as at least six opioid prescriptions in one year and either one or more years between the first and last prescription or an average of ≤30 days not covered by an opioid during that year.

RESULTS

A total of 4,252,809 opioid-naïve patients received their first opioid prescription between 2013 and 2016; 364,947 (8.6%) met the definition for chronic use. Those who developed chronic use were older (51.7 vs 45.6 years) and more likely to be female (53.6% vs 52.8%), and their first prescription had higher pill quantities (44.9 vs 30.2), higher morphine milligram equivalents (MME; 355.3 vs 200.0), and was more likely to be an extended-release formulation (2.9% vs 0.7%, all P < 0.001). When compared with internal medicine, the adjusted odds of chronic use were highest with anesthesiology (odds ratio [OR] = 1.46) and neurology (OR = 1.43) and lowest with ophthalmology (OR = 0.33) and gynecology (OR = 0.37).

CONCLUSIONS

Eight point six percent of opioid-naïve individuals who received an opioid prescription developed chronic use. This rate varied depending on the specialty of the provider who wrote the prescription. The risk of chronic use increased with higher MME content of the initial prescription and use of extended-release opioids.

Analgesic efficacy of morphine sulfate immediate release vs. oxycodone/acetaminophen for acute pain in the emergency department

OBJECTIVE

Previous research demonstrated that administration of Morphine Sulfate Immediate Release (MSIR) results in similar analgesic efficacy to Oxycodone but with significantly lesser degrees of euphoria and reward. The purpose of this study sit to investigate if MSIR combined with Acetaminophen can serve as an opioid analgesic alternative to Oxycodone combined with acetaminophen (Percocet) for acute pain in the Emergency Department (ED).

METHODS

A prospective, randomized, double-blind trial of ED patients aged 18 to 64 years presenting with moderate to severe acute pain as defined by an 11-point numeric rating scale (NRS) with an initial score of ≥5 (0 = no pain and 10 = very severe pain). Patients were randomized to receive either 15 mg MSIR combined with 650 mg of Acetaminophen or 10 mg Oxycodone combined with 650 mg Acetaminophen. Patients were assessed at baseline, 30, 45 and 60 min. The primary outcome was reduction in pain at 60 min. Secondary outcomes include drug likeability and adverse events.

RESULTS

80 patients were enrolled in the study (40 per group). Demographic characteristics were similar between the groups (P > 0.05). Mean NRS pain scores at baseline were 8.44 for the MSIR group and 8.53 for the Percocet group (P = 0.788). Mean pain scores decreased over time but remained similar between the groups: 30 min (6.03 vs. 6.43; P = 0.453), 45 min (5.31 vs. 5.48; P = 0.779), and 60 min (4.22 vs. 4.87; P = 0.346). Reduction in mean NRS pain scores were statistically significant from baseline to 30, 45 and 60 min within each group (P < 0.0001 at each time point for both groups). The largest NRS mean difference was from baseline to 60 min: 4.2 (95% CI: 3.43 to 5.01) for MSIR group and 3.61 (95% CI: 2.79 to 4.43) for Percocet group. No clinically significant changes or any serious adverse events were observed in either group.

CONCLUSION

MSIR provides similar analgesic efficacy as Percocet for short-term pain relief in the ED, similar rates of nausea/vomiting, and lower rates of likeability of the drug.

Relative addictive potential of opioid analgesic agents

Opioid overdoses and deaths continue to be a problem in the USA with a significant portion related to prescribed opioid analgesic agents. The role of pharmacogentic factors in opioid addiction is an active area of research. While all opioid analgesic agents have some addictive potential, it is clear that there are some with greater addictive potential. Oxycodone is the most widely abused opioid analgesic and it appears to predispose to chronic use with high likability by users. Fentanyl and hydromorphone are both very lipophilic allowing rapid penetration into the CNS, but are not rated as highly as other agents. Providers should consider the risk of addiction with the opioids they prescribe and give those with a lower addictive potential.

Methylation in Syn and Psd95 genes underlie the inhibitory effect of oxytocin on oxycodone-induced conditioned place preference

Oxycodone (Oxy) is one of the most effective analgesics in medicine, but is associated with the development of dependence. Recent studies demonstrating epigenetic changes in the brain after exposure to opiates have provided an insight into possible mechanisms underlying addiction. Oxytocin (OT), an endogenous neuropeptide well known for preventing drug abuse, is a promising pharmacotherapy to counteract addiction. Therefore, we explored the mechanism of Oxy addiction and the role of OT in Oxy-induced epigenetic alterations. In this study, drug-induced changes in conditioned place preference (CPP), i.e. the expression of synaptic proteins and synaptic density in the ventral tegmental area (VTA) were measured. We also sought to identify DNA methyltransferases (DNMTs), ten-eleven translocations (TETs), global 5-methylcytosine (5-mC), and DNA methylation of two genes implicated in plasticity (Synaptophysin, Syn; Post-synaptic density protein 95, Psd95). Oxy (3.0 mg/kg, i.p.) induced CPP acquisition in Sprague-Dawley rats. Oxy down-regulated DNMT1 and up-regulated TET1-3, leading to a decrease in global 5-mC levels and differential demethylation at exon 1 of Syn and exon 2 of Psd95. These changes in DNA methylation of Syn and Psd95 elevated the expression of synaptic proteins (SYN, PSD95) and synaptic density in the VTA. Pretreatment with OT (2.5 µg, i.c.v.) via its receptor specifically blocked Oxy CPP, normalized synaptic density, and regulated DNMT1 and TET2-3 causing reverse of DNA demethylation of Syn and Psd95. DNA methylation is an important gene regulation mechanism underlying Oxy CPP, and OT - via its receptor - could specifically inhibit Oxy addiction.