Oxycodone: a pharmacological and clinical review

The immunological and pharmacokinetic evaluation of Lipid-PLGA hybrid nanoparticle-based oxycodone vaccines

The current opioid epidemic is one of the most profound public health crises facing the United States. Despite that it has been under the spotlight for years, available treatments for opioid use disorder (OUD) and overdose are limited to opioid receptor ligands such as the agonist methadone and the overdose reversing drugs such as naloxone. Vaccines are emerging as an alternative strategy to combat OUD and prevent relapse and overdose. Most vaccine candidates consist of a conjugate structure containing the target opioid attached to an immunogenic carrier protein. However, conjugate vaccines have demonstrated some intrinsic shortfalls, such as fast degradation and poor recognition by immune cells. To overcome these challenges, we proposed a lipid-PLGA hybrid nanoparticle (hNP)-based vaccine against oxycodone (OXY), which is one of the most frequently misused opioid analgesics. The hNP-based OXY vaccine exhibited superior immunogenicity and pharmacokinetic efficacy in comparison to its conjugate vaccine counterpart. Specifically, the hNP-based OXY vaccine formulated with subunit keyhole limpet hemocyanin (sKLH) as the carrier protein and aluminum hydroxide (Alum) as the adjuvant (OXY-sKLH-hNP(Alum)) elicited the most potent OXY-specific antibody response in mice. The induced antibodies efficiently bound with OXY molecules in blood and suppressed their entry into the brain. In a following dose-response study, OXY-sKLH-hNP(Alum) equivalent to 60 μg of sKLH was determined to be the most promising OXY vaccine candidate moving forward. This study provides evidence that hybrid nanoparticle-based vaccines may be superior vaccine candidates than conjugate vaccines and will be beneficial in treating those suffering from OUD.

An extract of phase II and III trials on recent developments in managing neuropathic pain syndromes: diabetic peripheral neuropathy, trigeminal neuralgia, and postherpetic neuralgia

INTRODUCTION

Neuropathic pain (NP) conditions involve lesions to the somatosensory nervous system leading to chronic and debilitating pain. Many patients suffering from NP utilize pharmacological treatments with various drugs that seek to reduce pathologic neuronal states. However, many of these drugs show poor efficacy as well as cause significant adverse effects. Because of this, there is a major need for the development of safer and more efficacious drugs to treat NP.

AREAS COVERED

In this review, we analyzed current treatments being developed for a variety of NP conditions. Specifically, we sought drugs in phase II/III clinical trials with indications for NP conditions. Various databases were searched including Google Scholar, PubMed, and clinicaltrials.gov.

EXPERT OPINION

All the mentioned targets for treatments of NP seem to be promising alternatives for existing treatments that often possess poor side effect profiles for patients. However, gene therapy potentially offers the unique ability to inject a plasmid containing growth factors leading to nerve growth and repair. Because of this, gene therapy appears to be the most intriguing new treatment for NP.

Advances in animal models of prenatal opioid exposure

Neonatal opioid withdrawal syndrome (NOWS) is a growing public health concern. The complexity of in utero opioid exposure in clinical studies makes it difficult to investigate underlying mechanisms that could ultimately inform early diagnosis and treatments. Clinical studies are unable to dissociate the influence of maternal polypharmacy or the environment from direct effects of in utero opioid exposure, highlighting the need for effective animal models. Early animal models of prenatal opioid exposure primarily used the prototypical opioid, morphine, and opioid exposure that was often limited to a narrow period during gestation. In recent years, the number of preclinical studies has grown rapidly. Newer models utilize both prescription and nonprescription opioids and vary the onset and duration of opioid exposure. In this review, we summarize novel prenatal opioid exposure models developed in recent years and attempt to reconcile results between studies while critically identifying gaps within the current literature.

Treating neuropathic pain and comorbid affective disorders: Preclinical and clinical evidence

INTRODUCTION

Neuropathic pain (NP) significantly impacts quality of life and often coexists with affective disorders such as anxiety and depression. Addressing both NP and its psychiatric manifestations requires a comprehensive understanding of therapeutic options. This study aimed to review the main pharmacological and non-pharmacological treatments for NP and comorbid affective disorders to describe their mechanisms of action and how they are commonly used in clinical practice.

METHODS

A review was conducted across five electronic databases, focusing on pharmacological and non-pharmacological treatments for NP and its associated affective disorders. The following combination of MeSH and title/abstract keywords were used: "neuropathic pain," "affective disorders," "depression," "anxiety," "treatment," and "therapy." Both animal and human studies were included to discuss the underlying therapeutic mechanisms of these interventions.

RESULTS

Pharmacological interventions, including antidepressants, anticonvulsants, and opioids, modulate neural synaptic transmission to alleviate NP. Topical agents, such as capsaicin, lidocaine patches, and botulinum toxin A, offer localized relief by desensitizing pain pathways. Some of these drugs, especially antidepressants, also treat comorbid affective disorders. Non-pharmacological techniques, including repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and photobiomodulation therapy, modulate cortical activity and have shown promise for NP and mood disorders.

CONCLUSIONS

The interconnection between NP and comorbid affective disorders necessitates holistic therapeutic strategies. Some pharmacological treatments can be used for both conditions, and non-pharmacological interventions have emerged as promising complementary approaches. Future research should explore novel molecular pathways to enhance treatment options for these interrelated conditions.

A Multicenter Retrospective Observational Study Analyzing the Effect of Polypharmacy on Oxycodone Tolerability

Polypharmacy is becoming increasingly troublesome in the treatment of cancer. The aim of this study was to explore the effects of concomitant polypharmacy comprising drugs that inhibit CYP3A4 and/or CYP2D6 on the oxycodone tolerability in patients with cancer. We conducted a multicenter retrospective study encompassing 20 hospitals. The data used for the study were obtained during the first 2 wk of oxycodone administration. The incidence of oxycodone discontinuation or dose reductions due to side effects and oxycodone-induced nausea and vomiting (OINV) were compared between patients not treated with either inhibitor and those treated with concomitant CYP3A4 or CYP2D6 inhibitors. The incidence of oxycodone discontinuation or dose reductions in patients treated with ≥3 concomitant CYP2D6 inhibitors (18.2%) tended to be higher than that in patients without this treatment (8.2%; p = 0.09). Moreover, the incidence of OINV in patients treated with 2 concomitant CYP3A4 inhibitors (29.8%) was significantly higher than that in patients without this treatment (15.5%; p = 0.049). Multivariate analysis showed that more than two concomitant CYP3A4 inhibitors and no concomitant use of naldemedine were independent risk factors for OINV. Concomitant polypharmacy involving CYP3A4 inhibitors increases the risk of OINV. Therefore, medications concomitantly used with oxycodone should be optimized.

Comparison of different sustained-release opioids and acute respiratory conditions in patients with cancer and chronic kidney disease

STUDY OBJECTIVE

Few data are available on the association between the use of oxycodone in patients with chronic kidney disease (CKD) and acute respiratory conditions. The aim of this study was to investigate whether oxycodone is associated with an increased risk of acute respiratory conditions in patients with cancer and CKD compared with other opioids.

DESIGN AND SETTING

The data were obtained from a claims database in Japan. Patients with cancer and CKD who had received sustained-release opioids, including oral oxycodone, oral morphine, or transdermal fentanyl, between April 2014 and May 2021 were selected. The primary outcome was defined as an acute respiratory condition. Data for age and sex, morphine equivalent daily dose, concomitant use of specified medications, comorbidities defined based on the modified Charlson comorbidity index, substance use disorder, and lung cancer or metastatic lung cancer were investigated as covariates. Distribution of acute respiratory conditions was compared among the three sustained-release opioid groups using the log-rank test. Estimates of the incidence of acute respiratory conditions were compared among the groups using a Cox proportional hazards model with time-varying variables.

MAIN RESULTS

A significant difference in the distribution of acute respiratory conditions was found among the three groups (p < 0.01). Cox regression analysis showed a significantly higher risk of acute respiratory conditions with morphine (hazard ratio [HR]: 3.04, 95% confidence interval [CI]: 1.07-8.65, p = 0.04) compared with oxycodone but no significant difference in risk with oxycodone (HR 0.67, 95% CI: 0.32-1.38, p = 0.27) compared with fentanyl.

CONCLUSIONS

The findings suggest that the risk of acute respiratory conditions may be lower in patients with CKD who use oxycodone for cancer pain than in those who use morphine. Additionally, no difference in the risk of acute respiratory conditions was found between oxycodone and fentanyl use.

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.

Evaluation and Treatment of Acute Trauma Pain in Older Adults

In the context of an ageing population, the demographic sands of trauma are shifting. Increasingly, trauma units are serving older adults who have sustained injuries in low-energy falls from a standing height. Older age is commonly associated with changes in physiology, as well as an increased prevalence of frailty and multimorbidity, including cardiac, renal and liver disease. These factors can complicate the safe and effective administration of analgesia in the older trauma patient. Trauma services therefore need to adapt to meet this demographic shift and ensure that trauma clinicians are sufficiently skilled in treating pain in complex older people. This article is dedicated to the management of acute trauma pain in older adults. It aims to highlight the notable clinical challenges of managing older trauma patients compared with their younger counterparts. It offers an overview of the evidence and practical opinion on the merits and drawbacks of commonly used analgesics, as well as more novel and emerging analgesic adjuncts. A search of Medline (Ovid, from inception to 7 November 2022) was conducted by a medical librarian to identify relevant articles using keyword and subject heading terms for trauma, pain, older adults and analgesics. Results were limited to articles published in the last 10 years and English language. Relevant articles' references were hand-screened to identify other relevant articles. There is paucity of dedicated high-quality evidence to guide management of trauma-related pain in older adults. Ageing-related changes in physiology, the accumulation of multimorbidity, frailty and the risk of inducing delirium secondary to analgesic medication present a suite of challenges in the older trauma patient. An important nuance of treating pain in older trauma patients is the challenge of balancing iatrogenic adverse effects of analgesia against the harms of undertreated pain, the complications and consequences of which include immobility, pneumonia, sarcopenia, pressure ulcers, long-term functional decline, increased long-term care needs and mortality. In this article, the role of non-opioid agents including short-course non-steroidal anti-inflammatory drugs (NSAIDs) is discussed. Opioid selection and dosing are reviewed for older adults suffering from acute trauma pain in the context of kidney and liver disease. The evidence base and limitations of other adjuncts such as topical and intravenous lidocaine, ketamine and regional anaesthesia in acute geriatric trauma are discussed.

Perioperative Pain Management for Distal Radius Fractures

Distal radius fractures have a high incidence among both young and elderly patients, and in many instances require operative intervention. When operative intervention is employed, adequate pain management is essential to decrease postoperative complications, such as chronic pain and disability, while minimizing the risk of prolonged opioid use and dependence. Strategies to optimize pain management include regional anesthesia, preoperative dosing of medication, multimodal regimens, long-acting selective opioids at the time of surgery, corticosteroids, and non-pharmacologic therapies.

Pharmacological Treatments and Therapeutic Drug Monitoring in Patients with Chronic Pain

Pain is an unpleasant sensory and emotional experience that affects every aspect of a patient's life and which may be treated through different pharmacological and non-pharmacological approaches. Analgesics are the drugs most commonly used to treat pain, and in specific situations, the use of opioids may be considered with caution. These drugs, in fact, do not always induce optimal analgesia in patients, and several problems are associated with their use. The purpose of this narrative review is to describe the pharmacological approaches currently used for the management of chronic pain. We review several aspects, from the pain-scale-based methods currently available to assess the type and intensity of pain, to the most frequently administered drugs (non-narcotic analgesics and narcotic analgesics), whose pharmacological characteristics are briefly reported. Overall, we attempt to provide an overview of different pharmacological treatments while also illustrating the relevant guidelines and indications. We then report the strategies that may be used to reduce problems related to opioid use. Specifically, we focus our attention on therapeutic drug monitoring (TDM), a tool that could help clinicians select the most suitable drug and dose to be used for each patient. The actual potential of using TDM to optimize and personalize opioid-based pain treatments is finally discussed based on recent scientific reports.

Electrochemically Enabled Total Syntheses of Natural Products

Electrochemical techniques have helped to enable the total synthesis of natural products since the pioneering work of Kolbe in the mid 1800's. The electrochemical toolset grows every day and these new possibilities change the way chemists look at and think about natural products. This review provides a perspective on total syntheses wherein electrochemical techniques enabled the carbon─carbon bond formations in the skeletal assembly of important natural products, discussion of mechanistic details, and representative examples of the bond formations enabled over the last several decades. These bond formations are often distinctly different from those possible with conventional chemistries and allow assemblies complementary to other techniques.

Swallowing biomechanics in tracheostomised critically ill patients compared to age- and gender-matched healthy controls

Objective

The mechanistic effects of a tracheostomy on swallowing are unclear. Pharyngeal high-resolution manometry with impedance (P-HRM-I) is a novel swallow assessment tool providing quantifiable metrics. This study aimed to characterise swallowing biomechanics in tracheostomised critically ill (non-neurological) patients.

Design

Cohort study.

Setting

Australian tertiary hospital intensive care unit.

Participants

Tracheostomised adults, planned for decannulation.

Main outcome measures

Swallowing assessment using P-HRM-I, compared to healthy age- and gender-matched controls.

Results

In this tracheostomised cohort (n = 10), the Swallow Risk Index, a global measure of swallow function, was significantly elevated (p < 0.001). At the upper oesophageal sphincter (UOS), hypopharyngeal intrabolus pressure and UOS integrated relaxation pressure were significantly elevated (control 0.65 mmHg [-1.02, 2.33] v tracheostomy 13.7 mmHg [10.4, 16.9], P < 0.001; control -4.28 mmHg [-5.87, 2.69] v tracheostomy 12.2 mmHg [8.83, 15.6], P < 0.001, respectively). Furthermore, UOS opening extent and relaxation time were reduced (control 4.83 mS [4.60, 5.07] v tracheostomy 4.33 mS [3.97, 4.69], P = 0.002; control 0.52 s [0.49, 0.55] v tracheostomy 0.41 s [0.37, 0.45], P < 0.001, respectively). Total pharyngeal contractility (PhCI) measuring pharyngeal pressure generation was significantly elevated (control 199.5 mmHg cm.s [177.4, 221.6] v tracheostomy 326.5 mmHg cm.s [253.3, 399.7]; P = 0.001).

Conclusion

In a critically ill tracheostomised cohort, UOS dysfunction was the prevalent biomechanical feature, with elevated pharyngeal pressures. Pharyngeal weakness is not contributing to dysphagia in this cohort. Instead, elevated pharyngeal pressures may represent a compensatory mechanism to overcome the UOS dysfunction. Further studies to extend these findings may inform the development of timely and targeted rehabilitation.

Oxycodone vs. tramadol in postoperative parent-controlled intravenous analgesia in children: a prospective, randomized, double-blinded, multiple-center clinical trial

BACKGROUND

Management of acute postoperative pain is one of the major challenges in pediatric patients. Oral oxycodone has shown good pain relief in postoperative pain relief in children, but no studies have investigated intravenous oxycodone in this context.

OBJECTIVE

whether oxycodone PCIA can provide adequate and safe postoperative pain relief, in comparison to tramadol as reference opioid drug.

DESIGN

a randomized, double-blind, parallel, multi-center clinical trial.

SETTING

five university medical centers and three teaching hospitals in China.

PARTICIPANTS

patients aged 3-month-old to 6-year-old undergoing elective surgery under general anesthesia.

INTERVENTION

patients were randomly allocated to either tramadol (n = 109) or oxycodone (n = 89) as main postoperative opioid analgesic. Tramadol or oxycodone were administered with a loading dose at the end of surgery (1 or 0.1 mg.kg^-1, respectively), then with a parent-controlled intravenous device with fixed bolus doses only (0.5 or 0.05 mg.kg-1, respectively), and a 10-min lockout time.

OUTCOMES

the primary outcome was adequate postoperative pain relief, defined as a face, legs, activity, cry, and consolability (FLACC) score < 4/10 in the post-anesthesia care unit (PACU), with no need for an alternative rescue analgesia. FLACC was measured 10 min after extubation then every 10 min until discharge from PACU. Analgesia was currently conducted with the boluses of either tramadol or oxycodone if FLACC was ≥ 3, up to three bolus doses, after what rescue alternative analgesia was administered.

RESULTS

tramadol and oxycodone provided a similar level of adequate postoperative pain relief in PACU and in the wards. No significant differences were either noted for the raw FLACC scores, the bolus dose demand in PACU, the time between the first bolus dose and discharge from PACU, analgesic drug consumption, bolus times required in the wards, function activity score, or the parents' satisfaction. The main observed side effects in both groups were nausea and vomiting, with no difference between groups. However, patients in the oxycodone group showed less sedation levels and had a shorter stay in the PACU, compared with the tramadol group.

CONCLUSIONS

an adequate postoperative analgesia can be achieved with intravenous oxycodone, this with less side effects than tramadol. It can therefore be a choice for postoperative pain relief in pediatric patients.

TRIAL REGISTRATION

The study was registered at www.chictr.org.cn (Registration number: ChiCTR1800016372; date of first registration: 28/05/2018; updated date:06/01/2023).

A systematic review on the kappa opioid receptor and its ligands: New directions for the treatment of pain, anxiety, depression, and drug abuse

Kappa opioid receptor (KOR) is a member of the opioid receptor system, the G protein-coupled receptors that are expressed throughout the peripheral and central nervous systems and play crucial roles in the modulation of antinociception and a variety of behavioral states like anxiety, depression, and drug abuse. KOR agonists are known to produce potent analgesic effects and have been used clinically for the treatment of pain, while KOR antagonists have shown efficacy in the treatment of anxiety and depression. This review summarizes the history, design strategy, discovery, and development of KOR ligands. KOR agonists are classified as non-biased, G protein-biased, and β-arrestin recruitment-biased, according to their degrees of bias. The mechanisms and associated effects of the G protein signaling pathway and β-arrestin recruitment signaling pathway are also discussed. Meanwhile, KOR antagonists are classified as long-acting and short-acting, based on their half-lives. In addition, we have special sections for mixed KOR agonists and selective peripheral KOR agonists. The mechanisms of action and pharmacokinetic, pharmacodynamic, and behavioral studies for each of these categories are also discussed in this review.

Sex and chronic stress alter the distribution of glutamate receptors within rat hippocampal CA3 pyramidal cells following oxycodone conditioned place preference

Glutamate receptors have a key role in the neurobiology of opioid addiction. Using electron microscopic immunocytochemical methods, this project elucidates how sex and chronic immobilization stress (CIS) impact the redistribution of GluN1 and GluA1 within rat hippocampal CA3 pyramidal cells following oxycodone (Oxy) conditioned place preference (CPP). Four groups of female and male Sprague-Dawley rats subjected to CPP were used: Saline- (Sal) and Oxy-injected (3 mg/kg, I.P.) naïve rats; and Sal- and Oxy-injected CIS rats. GluN1: In both naive and CIS rats, Sal-females compared to Sal-males had elevated cytoplasmic and total dendritic GluN1. Following Oxy CPP, near plasmalemmal, cytoplasmic, and total GluN1 decreased in CA3 dendrites of unstressed females suggesting reduced pools of GluN1 available for ligand binding. Following CIS, Oxy-males (which did not acquire CPP) had increased GluN1 in all compartments of dendrites and spines of CA3 neurons. GluA1: There were no differences in the distribution GluA1 in any cellular compartments of CA3 dendrites in naïve females and males following either Sal or Oxy CPP. CIS alone increased the percent of GluA1 in CA3 dendritic spines in males compared to females. CIS Oxy-males compared to CIS Sal-males had an increase in cytoplasmic and total dendritic GluA1. Thus, in CIS Oxy-males increased pools of GluN1 and GluA1 are available for ligand binding in CA3 neurons. Together with our prior experiments, these changes in GluN1 and GluA1 following CIS in males may contribute to an increased sensitivity of CA3 neurons to glutamate excitation and a reduced capacity to acquire Oxy CPP.

Oxycodone relieves permeability damage and apoptosis of oxygen-glucose deprivation/reoxygenation-induced brain microvascular endothelial cells through ras homolog family member A (RhoA)/ Rho-associated coiled-coil containing kinases (ROCK)/ myosin light chain 2 (MLC2) signal

Cerebrovascular disease, an important cause of acute ischemic stroke, has attracted worldwide attention. Oxycodone has been widely used to treat various painful disorders. This study was designed to explore the mechanism of oxycodone in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced brain microvascular endothelial cell model. For the reliability of the results in the following experiments, the viability was firstly detected using CCK-8. With the application of LDH, TEER and TUNEL assays, the LDH expression, permeability and apoptosis of brain microvascular endothelial cells were detected, respectively. Besides, the mRNA and protein expressions of tight junction proteins and RhoA were measured using RT-qPCR and Western blot. Moreover, RT-qPCR was employed to evaluate the expressions of inflammatory cytokines. Western blot was adopted to measure the levels of RhoA, ROCK, MLC2 and apoptosis-related proteins. The results revealed that oxycodone attenuated permeability damage, inflammatory factor release and apoptosis of OGD/R-induced brain microvascular endothelial cells in a dose-dependent manner. It was also found that oxycodone could reduce the expressions of RhoA, ROCK and MLC2 in brain microvascular endothelial cells induced by OGD/R. More importantly, oxycodone exhibited desirable effects on OGD/R-induced brain microvascular endothelial cells through RhoA/ROCK/MLC2 signal. In conclusion, oxycodone relieved permeability damage and apoptosis of OGD/R-induced brain microvascular endothelial cells through RhoA/ROCK/MLC2 signal, suggesting that oxycodone might be an effective method for the improvement of cerebral ischemia-reperfusion injury.

The utility of maraviroc, an antiretroviral agent used to treat HIV, as treatment for opioid abuse? Data from MRI and behavioural testing in rats

BACKGROUND

Maraviroc is an antiretroviral agent and C-C chemokine coreceptor 5 (CCR5) antagonist that is currently used to treat human immunodeficiency virus. CCR5/μ-opioid receptor heterodimerization suggests that maraviroc could be a treatment for oxycodone abuse. We treated rats with maraviroc to explore its effect on oxycodone-seeking and its interference with the analgesic effects of oxycodone. We used resting-state blood-oxygen-level-dependent functional connectivity to assess the effect of maraviroc on oxycodone-enhanced coupling in the reward circuitry and performed behavioural tests to evaluate the effect of maraviroc on oxycodone rewarding properties and on oxycodone-seeking after prolonged abstinence.

METHODS

Two groups of rats were exposed to 8 consecutive days of oxycodone-conditioned place preference training and treatment with maraviroc or vehicle. Two additional groups were trained to self-administer oxycodone for 10 days and then tested for drug seeking after 14 days of abstinence with or without daily maraviroc treatment. We tested the effects of maraviroc on oxycodone analgesia using a tail-flick assay. We analyzed resting-state functional connectivity data using a rat 3-dimensional MRI atlas of 171 brain areas.

RESULTS

Maraviroc significantly decreased conditioned place preference and attenuated oxycodone-seeking behaviour after prolonged abstinence. The analgesic effect of oxycodone was maintained after maraviroc treatment. Oxycodone increased functional coupling with the accumbens, ventral pallidum and olfactory tubercles, but this was reduced with maraviroc treatment.

LIMITATIONS

All experiments were performed in male rats only.

CONCLUSION

Maraviroc treatment attenuated oxycodone-seeking in abstinent rats and reduced functional coupling in the reward circuitry. The analgesic effects of oxycodone were not affected by maraviroc.

Minocycline attenuates oxycodone-induced positive subjective responses in non-dependent, recreational opioid users

BACKGROUND

Recent data suggest that glial cells may be involved in the analgesic effects and abuse liability of opioids. Preclinical studies have demonstrated that mu-opioid-receptor-selective agonists, such as oxycodone, activate glia and increase the release of cytokines, causing a suppression of opioid-induced analgesic effects. Preclinical studies also show that certain medications, such as the broad-spectrum tetracycline antibiotic minocycline, inhibit opioid-induced glial activation and thereby enhance the analgesic effects of opioids. Importantly, minocycline reduces the rewarding effects of opioids at the same doses that it enhances opioid-induced analgesia.

AIMS

The purpose of the present study was to assess the effects of acute administration of minocycline on the subjective, physiological, and analgesic effects of oxycodone in human research volunteers.

DESIGN

This study was a within-subject, randomized, double-blind outpatient study. Participants completed five separate sessions in which they received 0, 100, or 200 mg minocycline (MINO) simultaneously with either 0 or 40 mg oxycodone (OXY). The subjective, physiological, and analgesic effects of OXY were measured before and repeatedly after drug administration.

SETTINGS AND PARTICIPANTS

Participants were between 21 and 45 years of age, non-treatment seeking, non-dependent recreational opioid users (N = 12). This study was conducted between 2013 and 2014 at the New York State Psychiatric Institute in New York, NY.

FINDINGS

MINO 100 and 200 mg were safe and well-tolerated in combination with OXY 40 mg. MINO 200 mg administered with OXY 40 mg attenuated OXY-induced positive subjective effects such as "Good Effect" and "Liking" compared to OXY alone. MINO did not alter the physiological or analgesic effects of OXY.

CONCLUSIONS

MINO may attenuate the abuse liability of mu-opioid-receptor-selective agonists.

Drug-Drug Interaction Between Oxycodone and Diazepam by a Combined in Silico Pharmacokinetic and Pharmacodynamic Modeling Approach

Opioids and benzodiazepines have complex drug-drug interactions (DDIs), which serve as an important source of adverse drug effects. In this work, we predicted the DDI between oxycodone (OXY) and diazepam (DZP) in the human body by applying in silico pharmacokinetic (PK) and pharmacodynamic (PD) modeling and simulation. First, we studied the PK interaction between OXY and DZP with a physiologically based pharmacokinetic (PBPK) model. Second, we applied molecular modeling techniques including molecular docking, molecular dynamics (MD) simulation, and the molecular mechanics/Poisson-Boltzmann surface area (MM-PBSA) free energy method to predict the PD-DDI between these two drugs. The PK interaction between OXY and DZP predicted by the PBPK model was not obvious. No significant interaction was observed between the two drugs at normal doses, though very high doses of DZP demonstrated a non-negligible inhibitory effect on OXY metabolism. On the contrary, the molecular modeling study shows that DZP has potential to compete with OXY at the same binding pocket of the active μ-opioid receptor (MOR) and κ-opioid receptor (KOR). MD simulation and MM-PBSA calculation results demonstrated that there is likely a synergetic effect between OXY and DZP binding to opioid receptors, as OXY is likely to target the active MOR while DZP selectively binds to the active KOR. Thus, pharmacokinetics contributes slightly to the DDI between OXY and DZP although an overdose of DZP has been brought to attention. Pharmacodynamics is likely to play a more important role than pharmacokinetics in revealing the mechanism of DDI between OXY and DZP.

High fructose corn syrup alters behavioural and neurobiological responses to oxycodone in rats

There are indications that sugars in the diet can play a role in vulnerability to opioid abuse. The current study examined a range of neuro-behavioural interactions between oxycodone (OXY) and high fructose corn syrup (HFCS). Male Sprague-Dawley rats had access to HFCS (0 or 50%) over 26 days in their home cages and were subsequently tested on place conditioning induced by 0, 0.16 and 2.5 mg/kg OXY (3 pairings of drug and saline, each 30 min), as well as on locomotor responses to 0, 0.16 and 2.5 mg/kg OXY, and in-vivo microdialysis was employed to measure dopamine (DA) levels in the nucleus accumbens (NAc) in response to 0 and 2.5 mg/kg OXY. A complex set of interactions between HFCS exposure and responses to OXY were observed: HFCS increased place preference induced by OXY, it enhanced the suppressant effect of OXY on locomotion, and it attenuated OXY-induced elevation in DA overflow in the NAc. Taken together, these findings suggest that nutrition has the potential to influence some responses to opioids which may be relevant to their abuse.

The pro- and anti-cancer effects of oxycodone are associated with epithelial growth factor receptor level in cancer cells

Background: Oxycodone is an opioid medication used for the treatment of pain in cancer patients. However, little is known on the direct effects of oxycodone on cancer cells. Aim: To determine the effects and mechanisms of oxycodone in cancer cells. Materials and Methods: Proliferation, survival and migration assays were performed on multiple types of cancer cells. Epithelial growth factor receptor (EGFR)/ERK/Akt pathway and oxidative stress were investigated after oxycodone treatment. Results: Oxycodone can either stimulate growth and migration without affecting survival in MDA-468 cells or inhibit growth and survival without affecting migration in SKBR3 and Caco2 cells. In addition, oxycodone can either attenuate or stimulate efficacy of chemotherapeutic drugs in cancer, depending on the type of cancer cells and nature of action of oxycodone as single drug alone. Our mechanism studies suggest that the stimulatory and inhibitory effects of oxycodone are associated with EGFR expression levels in cancer cells. In cancer cells with high EGFR level, oxycodone activates EGFR signaling in cancer cells, leading to stimulatory effects in multiple biological activities, and this is dependent on opioid receptor. In cancer cells with low EGFR level, oxycodone induces mitochondria-mediated caspase activity and oxidative stress and damage, leading to cell death. Conclusions: Our work is the first to demonstrate systematic analysis of oxycodone’s effects and mechanism of action in cancer. The activation of EGFR signaling by oxycodone may provide a new guide in the clinical use of oxycodone, in particular for cancer patients with high EGFR levels.

Potential implications of DMET ontogeny on the disposition of commonly prescribed drugs in neonatal and pediatric intensive care units

Introduction: Pediatric patients, especially neonates and infants, are more susceptible to adverse drug events as compared to adults. In particular, immature small molecule drug metabolism and excretion can result in higher incidences of pediatric toxicity than adults if the pediatric dose is not adjusted.Area covered: We reviewed the top 29 small molecule drugs prescribed in neonatal and pediatric intensive care units and compiled the mechanisms of their metabolism and excretion. The ontogeny of Phase I and II drug metabolizing enzymes and transporters (DMETs), particularly relevant to these drugs, are summarized. The potential effects of DMET ontogeny on the metabolism and excretion of the top pediatric drugs were predicted. The current regulatory requirements and recommendations regarding safe and effective use of drugs in children are discussed. A few representative examples of the use of ontogeny-informed physiologically based pharmacokinetic (PBPK) models are highlighted.Expert opinion: Empirical prediction of pediatric drug dosing based on body weight or body-surface area from the adult parameters can be inaccurate because DMETs are not mature in children and the age-dependent maturation of these proteins is different. Ontogeny-informed-PBPK modeling provides a better alternative to predict the pharmacokinetics of drugs in children.

Sex and chronic stress alter delta opioid receptor distribution within rat hippocampal CA1 pyramidal cells following behavioral challenges

Following oxycodone (Oxy) conditioned place preference (CPP), delta opioid receptors (DORs) differentially redistribute in hippocampal CA3 pyramidal cells in female and male rats in a manner that would promote plasticity and opioid-associative learning processes. However, following chronic immobilization stress (CIS), males do not acquire Oxy-CPP and the trafficking of DORs in CA3 pyramidal neurons is attenuated. Here, we examined the subcellular distribution of DORs in CA1 pyramidal cells using electron microscopy in these same cohorts.

CPP

Saline (Sal)-females compared to Sal-males have more cytoplasmic and total DORs in dendrites and more DOR-labeled spines. Following Oxy-CPP, DORs redistribute from near-plasmalemma pools in dendrites to spines in males.

CIS

Control females compared to control males have more near-plasmalemmal dendritic DORs. Following CIS, dendritic DORs are elevated in the cytoplasm in females and near-plasmalemma in males.

CIS plus CPP

CIS Sal-females compared to CIS Sal-males have more DORs on the plasmalemma of dendrites and in spines. After Oxy, the distribution of DORs does not change in either females or males.

Conclusion

Following Oxy-CPP, DORs within CA1 pyramidal cells remain positioned in naïve female rats to enhance sensitivity to DOR agonists and traffic to dendritic spines in naïve males where they can promote plasticity processes. Following CIS plus behavioral enrichment, DORs are redistributed within CA1 pyramidal cells in females in a manner that could enhance sensitivity to DOR agonists. Conversely, CIS plus behavioral enrichment does not alter DORs in CA1 pyramidal cells in males, which may contribute to their diminished capacity to acquire Oxy-CPP.

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.

Tracking down the brominated single electron oxidants in recent organic red-ox transformations: photolysis and photocatalysis

A wide range of organic and inorganic brominated compounds including molecular bromine have been extensively used as oxidants in many organic photo-redox transformations in recent years, an area of ever growing interest because of greener and milder approaches. The oxidation power of these compounds is utilized through both mechanistic pathways (by hydrogen atom transfer or HAT in the absence of a photocatalyst and a combination of single electron transfer or SET and/or HAT in the presence of a photocatalyst). Not only as terminal oxidants for regeneration of photocatalysts, but brominated reactants have also contributed to the oxidation of the reaction intermediate(s) to carry on the radical chain process in several reactions. Here in this review mainly the non-brominative oxidative product formations are discussed, carried out since the last two decades, skipping the instances where they acted as terminal oxidants only to regenerate photocatalysts. The reactions are used to generate natural products, pharmaceuticals and beyond.

Sex differences in oral oxycodone self-administration and stress-primed reinstatement in rats

The opioid epidemic has become a severe public health problem, with approximately 130 opioid-induced deaths occurring each day in the United States. Prescription opioids are responsible for approximately 40% of these deaths. Oxycodone is one of the most commonly abused prescription opioids, but despite its prevalent misuse, the number of preclinical studies investigating oxycodone-seeking behaviors is relatively limited. Furthermore, preclinical oxycodone studies that include female subjects are even more scarce, and it is critical that future work includes both sexes. Additionally, the oral route of administration is one of the most common routes for recreational users, especially in the early stages of drug experimentation. However, currently, only two studies have been published investigating operant oral oxycodone self-administration in rodents. Therefore, the primary goal of the present study was to establish an oral oxycodone operant self-administration model in adult male and female rats, as well as to examine a potential mechanism of stress-primed reinstatement. We found that females consumed significantly more oral oxycodone than males in operant self-administration sessions. We also found that active oxycodone self-administration was reduced by mu opioid receptor antagonism and by substitution of water for oxycodone solution. Lastly, we induced stress-primed reinstatement and found that this behavior was significantly attenuated by antagonism of the neurokinin-1 receptor, consistent with our prior work examining stress-induced reinstatement of alcohol- and cocaine-seeking.

Oxycodone stimulates normal and malignant hematopoietic progenitors via opioid-receptor-independent-β-catenin activation

Oxycodone is a common type of opioid used for the treatment of moderate to severe pain. Besides its analgesic effects on neuron cells, the effects of oxycodone on other cell types are yet to be elucidated. We previously demonstrated that oxycodone displayed both pro- and anti-cancer effects on bulk cancer cells. This work further investigated the effects of oxycodone on normal and malignant hematopoietic stem cells. Using hematopoietic CD34⁺ cells isolated from normal bone marrow (NBM) or patients with acute myeloid leukemia (AML), we showed that oxycodone activates hematopoietic cells regardless of cell development stage and malignant status. Oxycodone dose-dependently increases colony formation and self-renewal capacity of NBM and AML stem/progenitor cells, and promotes proliferation of AML bulk cells. NBM stem/progenitor cells are more sensitive to oxycodone than AML counterparts. In addition, oxycodone alleviates chemotherapy drug-induced toxicity in AML stem/progenitor cells. Mechanism studies demonstrate that oxycodone acts on hematopoietic cells in an opioid-receptor-independent manner. Oxycodone did not affect epithelial growth factor receptor (EGFR) signaling neither but stimulated Wnt/β-catenin signaling. Rescue studies via depleting β-catenin using genetic and pharmacological approaches confirmed that β-catenin was required for the activation of hematopoietic cells induced by oxycodone. Our work demonstrates 1) the protective role of oxycodone in malignant hematopoietic cells from chemotherapy; 2) stimulatory effects of oxycodone in normal hematopoietic stem cells; and 3) ability of oxycodone in Wnt signaling activation.

Mild Cognitive Impairment and Decline in Resting State Functional Connectivity after Total Knee Arthroplasty with General Anesthesia

BACKGROUND

Research shows that older adults can have a decline in three key resting state networks (default mode network, central executive network, and salience network) after total knee arthroplasty and that patients' pre-surgery brain and cognitive integrity predicts decline.

OBJECTIVES

First, to assess resting state network connectivity decline from the perspective of nodal connectivity changes in a larger older adult surgery sample. Second, to compare pre-post functional connectivity changes in mild cognitive impairment (MCI) versus non-MCI.

METHODS

Surgery (n = 69) and non-surgery (n = 65) peers completed a comprehensive preoperative neuropsychological evaluation and pre- and acute (within 48 hours) post-surgery/pseudo-surgery functional brain magnetic resonance imaging scan. MCI was classified within both (MCI surgery, n = 13; MCI non-surgery, n = 10). Using standard coordinates, we defined default mode network, salience network, central executive network, and the visual network (serving as a control network). The functional connectivity of these networks and brain areas (nodes) that make up these networks were examined for pre-post-surgery changes through paired samples t-test and ANOVA.

RESULTS

There was a decline in RSN connectivity after surgery (p < 0.05) only in the three cognitive networks (not the visual network). The default mode and salience network showed nodal connectivity changes (p < 0.01). MCI surgery had greater functional connectivity decline in DMN and SN. Non-surgery participants showed no significant functional connectivity change.

CONCLUSION

Surgery with general anesthesia selectively alters functional connectivity in major cognitive resting state networks particularly in DMN and SN. Participants with MCI appear more vulnerable to these functional changes.

Comparing rates and characteristics of ambulance attendances related to extramedical use of pharmaceutical opioids in Victoria, Australia from 2013 to 2018

BACKGROUND AND AIMS

Despite increases in opioid prescribing and related morbidity and mortality, few studies have comprehensively documented harms across opioid types. We examined a population-wide indicator of extramedical pharmaceutical opioid-related harm to determine if the supply-adjusted rates of ambulance presentations, the severity of presentations or other attendance characteristics differed by opioid type.

DESIGN

Retrospective observational study of coded ambulance patient care records related to extramedical pharmaceutical opioid use, January 2013 to September 2018.

SETTING

Australia CASES: Primary analyses used Victorian data (n = 9823), with available data from other Australian jurisdictions (n = 4338) used to determine generalizability.

MEASUREMENTS

We calculated supply-adjusted rates of attendances using Poisson regression, and used multinomial logistic regression to compare demographic, presentation severity, mental health, substance use and other characteristics of attendances associated with seven pharmaceutical opioids.

FINDINGS

In Victoria, the highest rates of attendance [per 100 000 oral morphine equivalent mg (OME)] were for codeine (0.273/100 000) and oxycodone (0.113/100 000). The lowest rates were for fentanyl (0.019/100 000) and tapentadol (0.005/100 000). Oxycodone-naloxone rates (0.031/100 000) were lower than for oxycodone as a single ingredient (0.113/100 000). Fentanyl-related attendances were associated with the most severe characteristics, most likely to be an accidental overdose, most likely to have naloxone administered and least likely to be transferred to hospital. In contrast, codeine-related attendances were more likely to involve suicidal thoughts/behaviours, younger females and be transported to hospital. Supply-adjusted attendance rates for individual opioids were stable over time. Victorian states were broadly consistent with non-Victorian states.

CONCLUSIONS

In Australia, rates and characteristics of opioid-related harm vary by opioid type. Supply-adjusted ambulance attendance rates appear to be both stable over time and unaffected by large changes in supply.

Organophotocatalytic N-Demethylation of Oxycodone Using Molecular Oxygen

N‐Demethylation of oxycodone is one of the key steps in the synthesis of important opioid antagonists like naloxone or analgesics like nalbuphine. The reaction is typically carried out using stoichiometric amounts of toxic and corrosive reagents. Herein, we present a green and scalable organophotocatalytic procedure that accomplishes the N‐demethylation step using molecular oxygen as the terminal oxidant and an organic dye (rose bengal) as an effective photocatalyst. Optimization of the reaction conditions under continuous flow conditions using visible‐light irradiation led to an efficient, reliable, and scalable process, producing noroxycodone hydrochloride in high isolated yield and purity after a simple workup.

Effects of Adding Oxycodone to Ropivacaine on Labor Analgesia: A Randomized Controlled Trial

BACKGROUND

It has been reported that oxycodone is superior to the other opioids for the treatment of visceral pain. During the first stage of labor, pain is mainly caused by uterine contractions (visceral pain). It seems that oxycodone is more suitable for labor analgesia. During this study, we investigated the effects of adding oxycodone to ropivacaine on epidural analgesia during labor.

MATERIALS AND METHODS

Eighty nulliparous parturients were randomly divided into 2 groups. Group A received 0.2 mg/mL oxycodone plus 0.1% ropivacaine for epidural analgesia and group C (control group) received 0.1% ropivacaine alone for epidural analgesia. The onset time and duration of analgesia, duration of labor stages, delivery outcome, analgesic effect, Bromage scores, blood pressure, heart rate, and neonatal Apgar scores were recorded. Umbilical arterial blood was collected to analyze. Side effects, if any, were also recorded.

RESULTS

The visual analog scale of pain was lower at 2 and 4 hours after analgesia and 10 cm cervical dilatation in group A compared with group C (P=0.021, 0.018, and 0.009, respectively). The onset time of analgesia was shorter in group A than that in group C (13.3±2.8 vs. 14.9±3.6 min, P=0.032). There were no significant differences between the 2 groups in terms of the duration of labor stages, delivery outcome, Bromage score, neonatal Apgar score, or umbilical arterial blood pH. The duration of analgesia was significantly longer in group A than in group C (326.2±56.5 vs. 68.4±10.5 min, P=0.000), but the incidence of pruritus was higher in group A than in group C (10% vs. 0%, P=0.115).

CONCLUSIONS

This study demonstrates that epidural oxycodone may accelerate the onset of analgesia and obviously prolong the duration of analgesia during labor without increasing adverse effects associated with the neonate. However, it may cause a higher incidence of maternal pruritus (registration number: ChiCTR1800016483).

Comparing cost and effectiveness of IVPCA morphine with perioperative multimodal analgesia of oral etoricoxib and oxycontin: A retrospective study

Introduction

Good pain control modality for post total knee replacement promotes patient's comfort and facilitates functional recovery, which may prevent post-operative complications; and shorten hospital stay. Therefore, manage pain efficiently and effectively have financial implications to the hospital. This retrospective study analyzed the clinical outcomes and costs of the intravenous (IV) patient-controlled analgesia (PCA) with a new perioperative multimodal analgesia (PMA) of using etoricoxib and oxycontin.

Methods

This retrospective study analyzed a total of 102 inpatients, 53 received both IVPCA and regular oral analgesics from September 2016 to February 2017, while 49 received preemptive oral etoricoxib before surgery and duly together with oxycontin and paracetamol after surgery from September 2017 to February 2018. Pain scores as the primary outcome were measured by Numeric Rating Scale (0–10) at rest (NRS-R) and on movement (NRS-M). They were analyzed by one-way analysis of covariance (ANCOVA). Other outcomes included side effects from analgesics, range of motion (ROM^o), patient satisfaction, length of hospital stay and costs of medications.

Results

Patients in PMA group achieved better outcomes than PCA group. NRS-M of PMA group shown lower mean pain score and (standard error) than PCA group (2.96 [0.31] vs 4.26 [0.29]; p = 0.003), side effects from analgesics (18% vs 45%), ROM≥ 90° (55.1% vs 30.2%), patient satisfaction (8.97 vs 7.5 out of 10; p = 0.005), and length of hospital stay (6 days vs 8 days; p < 0.001). Moreover, the medication cost of PMA was 59.9% lower than PCA regimen.

Conclusions

This PMA approach achieved better outcomes and saved hospital costs.

Adult Cancer Pain, Version 3.2019, NCCN Clinical Practice Guidelines in Oncology

In recent years, the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Adult Cancer Pain have undergone substantial revisions focusing on the appropriate and safe prescription of opioid analgesics, optimization of nonopioid analgesics and adjuvant medications, and integration of nonpharmacologic methods of cancer pain management. This selection highlights some of these changes, covering topics on management of adult cancer pain including pharmacologic interventions, nonpharmacologic interventions, and treatment of specific cancer pain syndromes. The complete version of the NCCN Guidelines for Adult Cancer Pain addresses additional aspects of this topic, including pathophysiologic classification of cancer pain syndromes, comprehensive pain assessment, management of pain crisis, ongoing care for cancer pain, pain in cancer survivors, and specialty consultations.

Oxycodone suppresses the apoptosis of hippocampal neurons induced by oxygen-glucose deprivation/recovery through caspase-dependent and caspase-independent pathways via κ- and δ-opioid receptors in rats

Cerebral ischemia/reperfusion injury (CIRI) can lead to perioperative neurocognitive disorders (PND) during clinical recanalization procedures in cerebral vessels, principally due to neuronal apoptosis in the hippocampus. Oxycodone appears to be a multiple opioid receptor agonist and exerts intrinsic antinociception activity via κ-opioid receptor (KOR). Recent evidence has revealed that activation of both δ-opioid receptor (DOR) and KOR can provide neuroprotection against CIRI in vivo and in vitro. In our study, we established an oxygen-glucose deprivation/recovery (OGD/R) model with fetal hippocampal neurons and found that oxycodone could induce CIRI tolerance in these neurons, primarily through KOR and DOR. Possible mechanisms might involve the regulatory effect of oxycodone on the MAPK-Bcl2/Bax-caspase-9-caspase-3 pathway, as well as its inhibitory effect on cellular reactive oxygen species (ROS) production and mitochondrial membrane potential activation. Taken together, our findings may indicate a potential method for the prevention and treatment of PND associated with CIRI.

Efficacy and safety of sustained-release oxycodone compared with immediate-release morphine for pain titration in cancer patients: A multicenter, open-label, randomized controlled trial (SOCIAL)

BACKGROUND

The study aims to investigate the effect and safety of sustained-release oxycodone hydrochloride as background dose on pain titration in patients with moderate-to-severe cancer pain.

MATERIAL AND METHODS

Adult patients scheduled with a regular strong opioid for cancer-related pain were recruited and randomly assigned to sustained-release oxycodone group (tablets, 12 hourly) and immediate-release morphine group (5 mg initially, hourly). All patients were hourly reassessed for efficacy and dose titration.

RESULTS

The primary end point was the number of titration cycles required to achieve adequate pain relief (numerical rating scale, NRS ≤ 3). Secondary end points included the proportion of patients achieving adequate pain relief during each cycle, potential predictive factors for titration performance, and side effects. Ninety (94.7%) patients in oxycodone group and 78 (86.7%) patients in morphine group achieved adequate pain control during 1 to 4 cycles of titration. Patients in oxycodone group reached adequate pain control within the first 2 cycles of titration, which was significantly shorter than morphine group wherein the number of titration cycles ranged from 1 to 4 (P = .034). Oxycodone prescription significantly increased the response rate of patients to morphine titration during the first cycle of titration (P = .010). The initial NRS score and oxycodone administration were significantly associated with titration performance. The mild or moderate adverse effects were similar in 2 groups, while severe adverse effects were only identified in morphine group (P = .001).

CONCLUSION

Use of background sustained-release oxycodone is more efficient and better tolerated on dose titration than immediate-release morphine.

Review of Treatment for Central Spinal Neuropathic Pain and Its Effect on Quality of Life: Implications for Neuromyelitis Optica Spectrum Disorder

OBJECTIVES

Neuromyelitis optica spectrum disorder (NMOSD) causes disabling and persistent central neuropathic pain (NP). Because the pain syndrome in NMOSD is severe and often intractable to analgesic treatment, it interferes with quality of life in patients. No interventional trials have been published looking at response to interventions for pain in NMOSD. This is a synthesis of the literature surveying the impact on quality of life of interventions in all mechanisms of central spinal NP. This review has important implications for management of pain in NMOSD.

METHODS AND DATA SOURCES

A systematic database search was conducted using PubMed, Embase, and CINAHL Plus with keywords including "spinal cord," "quality of life," and "neuropathic pain" in an attempt to identify original research that targeted spinal NP treatment and used quality of life as an outcome measure. Both pharmacologic and nonpharmacologic treatments were sought out.

RESULTS

Twenty-one studies meeting our eligibility criteria were identified and evaluated, 13 using pharmacologic treatments and 8 using nonpharmacologic interventions. Overall, sample sizes were modest, and effects on decreasing pain and/or improving quality of life were suboptimal.

CONCLUSIONS

This review provides researchers with a foundation from which to start a more thorough and thoughtful investigation into the management of NP in NMOSD and underscores the importance of including quality of life as a clinically meaningful outcome measure.

Sex Differences in Neuroplasticity- and Stress-Related Gene Expression and Protein Levels in the Rat Hippocampus Following Oxycodone Conditioned Place Preference

Prescription opioid abuse is a serious public health issue. Recently, we showed that female and male Sprague-Dawley rats acquire conditioned place preference (CPP) to the mu opioid receptor agonist oxycodone. Anatomical analysis of the hippocampus from these rats unveiled sex differences in the opioid system in a way that would support excitation and opiate associative learning processes especially in females. In this study, we examined the expression and protein densities of opioid, plasticity, stress and related kinase and signaling molecules in the hippocampus of female and male rats following oxycodone CPP. Oxycodone CPP females have: a) increases in ARC (activity regulated cytoskeletal-associated protein)-immunoreactivity (ir) in CA3 pyramidal cells; b) decreases in Npy (neuropeptide Y) gene expression in the medial hippocampus but higher numbers of NPY-containing hilar interneurons compared to males; c) increases in Crhr2 (corticotropin releasing factor receptor 2) expression in CA2/3; d) increases in Akt1 (AKT serine/threonine kinase 1) expression in medial hippocampus; and e) decreases in phosphorylated MAPK (mitogen activated protein kinase)-ir in CA1 and dentate gyrus. Oxycodone CPP males have: a) increases in Bdnf (brain derived-neurotrophic factor) expression, which is known to be produced in granule cells, relative to females; b) elevated Mapk1 expression and pMAPK-ir in the dentate hilus which harbors newly generated granule cells; and c) increases in CRHR1-ir in CA3 pyramidal cell soma. These sex-specific changes in plasticity, stress and kinase markers in hippocampal circuitry parallel previously observed sex differences in the opioid system after oxycodone CPP.

Effect of different doses of intravenous oxycodone and fentanyl on intubation-related hemodynamic responses: A prospective double-blind randomized controlled trial (CONSORT)

BACKGROUND

Intubation using direct laryngoscopy is a risky and painful procedure that is associated with undesirable hemodynamic changes such as tachycardia, hypertension, and arrhythmia. Recently, intravenous oxycodone was introduced and used for the control of acute postoperative pain and to attenuate intubation-related hemodynamic responses (IRHRs), but there is insufficient information regarding its proper dosage. We investigated the attenuating effects of different doses of oxycodone and fentanyl on IRHRs.

METHODS

For calculating oxycodone effective dose (ED95), which attenuated all IRHR changes to less than 20% over baseline values in 95% of male patients at 1 minute after intubation, oxycodone 0.1 mg/kg was injected for the first patient 1 hour before intubation, and the next dose for each subsequent patient was determined by the response of the previous patient using Dixon up-and-down method with an interval of 0.01 mg/kg. After obtaining the predictive oxycodone ED95, 148 patients were randomly allocated to groups receiving normal saline (group C), oxycodone ED95 (group O1), oxycodone 2 × ED95 (group O2), or fentanyl 2 μg/kg (group F). We recorded the incidence of "success" as a less than 20% change from baseline values in all IRHRs 1 minute after intubation.

RESULTS

The predictive oxycodone ED95 was 0.091 (0.081-0.149) mg/kg. The incidence of "success" was highest in group O2 (75.7%), followed by group O1 (62.2%) and group F (45.9%) with significant differences between the groups (P < .001). The systolic, diastolic, mean arterial pressure, and heart rate were not significantly different among groups after administration of either oxycodone or fentanyl. The percentage hemodynamic changes of the group O2 were significantly lower than those of groups F and O1, but the absolute percentage hemodynamic changes were not significantly different among groups F, O1, and O2. The recalculated oxycodone ED95 with probit analysis (0.269 mg/kg) was needed to prevent any arterial pressure and heart rate changes.

CONCLUSIONS

Oxycodone 0.182 mg/kg is more effective in attenuating all IRHRs than fentanyl 2 μg/kg with safe hemodynamic changes. Further research is required to determine if the recalculated oxycodone ED95 (0.269 mg/kg) is also effective and hemodynamically safe for preventing all IRHRs.

Comparison of the antinociceptive profiles of morphine and oxycodone in two models of inflammatory and osteoarthritic pain in rat

Oxycodone and morphine are two opioid drugs commonly used for the treatment of moderate to severe pain. However, their use in the management of noncancer pain remains a controversial issue and, in this respect, the evidence on their effectiveness and safety, particularly in osteoarthritis, is being questioned. In order to analyse their analgesic profile, two different pain models in rats were used: the formalin-induced inflammatory pain and the monosodium iodoacetate (MIA)-induced knee osteoarthritic pain. Drugs were administered systemically (i.p.) and their antinociceptive effect and potency were assessed. In the formalin test, both morphine and oxycodone produced a dose-dependent antinociceptive effect, but oxycodone outdid morphine in terms of effectiveness and potency (nearly two times) in the early (acute nociceptive) as in the late phase (inflammatory). In the osteoarthritis model, both drugs reduced movement-evoked pain (knee-bend test), mechanical allodynia (von Frey test) and heat hyperalgesia (Plantar test). Pretreatment with naloxone and naloxone methiodide reduced morphine and oxycodone effects. Peripheral mu-opioid receptors play a crucial role in the antinociceptive effect of both drugs on movement-evoked pain and heat hyperalgesia, but not on tactile allodynia. The main finding of our study is that oxycodone has a better antinociceptive profile in the inflammatory and osteoarthritic pain, being more effective than morphine at 14 days post-MIA injection (phase with neuropathic pain); it overcame the morphine effect by improving the movement-induced pain, tactile allodynia and heat hyperalgesia. Therefore, oxycodone could be an interesting option to treat patients suffering from knee osteoarthritis when opioids are required.

Chronic immobilization stress primes the hippocampal opioid system for oxycodone-associated learning in female but not male rats

In adult female, but not male, Sprague Dawley rats, chronic immobilization stress (CIS) increases mossy fiber (MF) Leu-Enkephalin levels and redistributes delta- and mu-opioid receptors (DORs and MORs) in hippocampal CA3 pyramidal cells and GABAergic interneurons to promote excitation and learning processes following subsequent opioid exposure. Here, we demonstrate that CIS females, but not males, acquire conditioned place preference (CPP) to oxycodone and that CIS "primes" the hippocampal opioid system in females for oxycodone-associated learning. In CA3b, oxycodone-injected (Oxy) CIS females relative to saline-injected (Sal) CIS females exhibited an increase in the cytoplasmic and total densities of DORs in pyramidal cell dendrites so that they were similar to Sal- and Oxy-CIS males. Consistent with our earlier studies, Sal- and Oxy-CIS females but not CIS males had elevated DOR densities in MF-CA3 dendritic spines, which we have previously shown are important for opioid-mediated long-term potentiation. In the dentate gyrus, Oxy-CIS females had more DOR-labeled interneurons than Sal-CIS females. Moreover, Sal- and Oxy-CIS females compared to both groups of CIS males had elevated levels of DORs and MORs in GABAergic interneuron dendrites, suggesting capacity for greater synthesis or storage of these receptors in circuits important for opioid-mediated disinhibition. However, more plasmalemmal MORs were on large parvalbumin-containing dendrites of Oxy-CIS males compared to Sal-CIS males, suggesting a limited ability for increased granule cell disinhibition. These results suggest that low levels of DORs in MF-CA3 synapses and hilar GABAergic interneurons may contribute to the attenuation of oxycodone CPP in males exposed to CIS.

Different effects of oxycodone and remifentanil in patients undergoing ultrasound-guided percutaneous radiofrequency ablation of hepatic cancer: a randomized trial

Background

Percutaneous radiofrequency ablation (RFA) is a recently introduced alternative technique for the treatment of hepatic cancer. Anesthesia is required for RFA of hepatic cancer to achieve patient comfort and immobilization during this painful procedure. The purpose of this study was to investigate the analgesic efficacy and evaluate the safety of a single intravenous injection of oxycodone hydrochloride for this procedure.

Patients and methods

A total of 120 American Society of Anesthesiologists class I–II grade patients for elective ultrasound-guided percutaneous RFA were enrolled in this randomized controlled trial. Patients were randomized (1:1) to receive either a single intravenous injection of oxycodone (group O) or continuous infusion of remifentanil (group R). Both groups received the continuous infusion of dexmedetomidine for sedation. Visual analog scale (VAS), rescue analgesic, and side effects were checked during the periprocedural period. In addition, patient and oncologist satisfaction on a scale of 1–5 were determined.

Results

VAS score in group O was significantly lower than in group R at 1, 2, and 3 hours after RFA, and patients in group O required analgesics significantly later and less doses in the first 24 hours after RFA. The occurrence of unwanted body movements was significantly lower in group O. We found no complications including allergic reaction, excessive sedation, and chest wall rigidity in all patients. The patient satisfaction score was significantly higher in group O than that in group R.

Conclusion

Ultrasound-guided percutaneous RFA for hepatic cancer can be completed both with continuous infusion of remifentanil or a single intravenous injection of oxycodone. However, oxycodone hydrochloride provides better patient experience with higher satisfactory score and less unwanted body movements, relieves post-procedural pain better, and is not associated with an increase in adverse effects.

Can neuroimaging help combat the opioid epidemic? A systematic review of clinical and pharmacological challenge fMRI studies with recommendations for future research

The current opioid epidemic is an urgent public health problem, with enormous individual, societal, and healthcare costs. Despite effective, evidence-based treatments, there is significant individual variability in treatment responses and relapse rates are high. In addition, the neurobiology of opioid-use disorder (OUD) and its treatment is not well understood. This review synthesizes published fMRI literature relevant to OUD, with an emphasis on findings related to opioid medications and treatment, and proposes areas for further research. We conducted a systematic literature review of Medline and Psychinfo to identify (i) fMRI studies comparing OUD and control participants; (ii) studies related to medication, treatment, abstinence or withdrawal effects in OUD; and (iii) studies involving manipulation of the opioid system in healthy individuals. Following application of exclusionary criteria (e.g., insufficient sample size), 45 studies were retained comprising data from ~1400 individuals. We found convergent evidence that individuals with OUD display widespread heightened neural activation to heroin cues. This pattern is potentiated by heroin, attenuated by medication-assisted treatments for opioids, predicts treatment response, and is reduced following extended abstinence. Nonetheless, there is a paucity of literature examining neural characteristics of OUD and its treatment. We discuss limitations of extant research and identify critical areas for future neuroimaging studies, including the urgent need for studies examining prescription opioid users, assessing sex differences and utilizing a wider range of clinically relevant task-based fMRI paradigms across different stages of addiction.

Comparison of analgesic efficacy of oxycodone and fentanyl after total hip replacement surgery: A randomized controlled trial

BACKGROUND

Total hip replacement (THR) is often accompanied by severe postoperative pain. We aimed to study whether oxycodone can be an effective alternative for fentanyl in the management of early postoperative pain after total hip replacement.

METHODS

We conducted a randomized controlled trial on 46 patients scheduled to undergo THR. We followed a standard general anesthetic technique, with endotracheal intubation. Twenty minutes before the end of surgery, single bolus injection of fentanyl, 50 μg (fentanyl group [group F], n = 23) or oxycodone, 4 mg (oxycodone group [group O], n = 23) was administered intravenously. Numeric rating scale (NRS) was used to assess pain in the post-anesthesia care unit (PACU). All patients had intravenous patient-controlled analgesia (PCA) with 10 μg/kg of fentanyl for 48 hours. Intravenous boluses of 50 μg were administered for breakthrough pain. The cumulative opioid dose administered at 6, 12, 24, and 48 h after surgery were recorded. A P value of less than .05 was considered statistically significant.

RESULTS

The NRS of group O in the PACU was significantly lower (P <.05); fewer patients in group O required additional fentanyl boluses in the PACU (P <.05). The cumulative opioid requirement was significantly less in group O at 6, 12, 24, and 48 hours after surgery. (P <.05) CONCLUSIONS:: A single bolus injection of oxycodone is more effective than that of fentanyl in the acute phase of postoperative pain after THR. It may be used as an alternative drug for fentanyl in pain control after orthopedic surgery.

Effects of chronic fentanyl administration on behavioral characteristics of mice

Background

Fentanyl, a synthetic opioid categorized as a narcotic analgesic, has a 100‐ to 200‐fold stronger effect than most opioids, such as morphine. Fatal accidents due to chronic use and abuse of fentanyl are a worldwide social problem. One reason for the abuse of fentanyl is its psychostimulant effects that could induce behavioral changes. The effects of chronic fentanyl administration on behavior, however, are unclear.

Methods

Adult male C57BL/6J mice were chronically administered fentanyl (0.03 or 0.3 mg/kg/d i.p.), and various behaviors were assessed using a behavioral test battery.

Results

Mice chronically administered a high dose of fentanyl (0.3 mg/kg/d) exhibited decreased anxiety‐like behavior as assessed by the open field and elevated plus maze tests. On the other hand, interruption of fentanyl administration led to increased anxiety‐like behavior as observed in the light and dark transition test. The hot plate test revealed that chronic administration of fentanyl reduced pain sensitivity. High‐dose chronic fentanyl administration reduced the locomotor stimulatory effects of cocaine. The results, however, failed to reach the threshold for study‐wide statistical significance.

Conclusion

Chronic fentanyl administration induces some behavioral changes in mice. Although further studies are needed to clarify the underlying mechanisms of the behavioral effects of chronic fentanyl administration, our findings suggest that fentanyl is safe under properly controlled conditions.

To investigate the effects of long‐term fentanyl use on brain function, adult male C57BL/6J mice were chronically administered fentanyl (0.03 or 0.3 mg/kg/d ip) and analyzed in a behavioral test battery. Chronic fentanyl administration reduced anxiety‐like behavior, pain sensitivity, and the locomotor stimulatory effects of cocaine in mice. The results, however, failed to reach the threshold for study‐wide statistical significance.

Continuing war on pain: a personalized approach to the therapy with nonsteroidal anti-inflammatory drugs and opioids

Successful pain management requires the delivery of analgesia with minimal risk of adverse drug reactions. Nonsteroidal anti-inflammatory drugs and opioids remain the mainstay of treatment for the majority of patients. Unfortunately, almost 50% of all patients experience inadequate pain relief and serious side effects. Allelic variants in genes coding for target proteins, transporters and enzymes, which govern analgesic drugs action and their fate in the organism, might explain inter-individual variability in pain severity and in drug-induced pain relief and toxicities. Additionally, it seems that epigenetic changes contribute to the highly variable response to pain treatment. Therefore, pharmacogenomic testing might be a valuable tool for personalization of pain treatment, with a multidisciplinary team approach involved.

Sex Differences in the Rat Hippocampal Opioid System After Oxycodone Conditioned Place Preference

Although opioid addiction has risen dramatically, the role of gender in addiction has been difficult to elucidate. We previously found sex-dependent differences in the hippocampal opioid system of Sprague-Dawley rats that may promote associative learning relevant to drug abuse. The present studies show that although female and male rats acquired conditioned place preference (CPP) to the mu-opioid receptor (MOR) agonist oxycodone (3 mg/kg, I.P.), hippocampal opioid circuits were differentially altered. In CA3, Leu-Enkephalin-containing mossy fibers had elevated levels in oxycodone CPP (Oxy) males comparable to those in females and sprouted in Oxy-females, suggesting different mechanisms for enhancing opioid sensitivity. Electron microscopy revealed that in Oxy-males delta opioid receptors (DORs) redistributed to mossy fiber-CA3 synapses in a manner resembling females that we previously showed is important for opioid-mediated long-term potentiation. Moreover, in Oxy-females DORs redistributed to CA3 pyramidal cell spines, suggesting the potential for enhanced plasticity processes. In Saline-injected (Sal) females, dentate hilar parvalbumin-containing basket interneuron dendrites had fewer MORs, however plasmalemmal and total MORs increased in Oxy-females. In dentate hilar GABAergic dendrites that contain neuropeptide Y, Sal-females compared to Sal-males had higher plasmalemmal DORs, and near-plasmalemmal DORs increased in Oxy-females. This redistribution of MORs and DORs within hilar interneurons in Oxy-females would potentially enhance disinhibition of granule cells via two different circuits. Together, these results indicate that oxycodone CPP induces sex-dependent redistributions of opioid receptors in hippocampal circuits in a manner facilitating opioid-associative learning processes and may help explain the increased susceptibility of females to opioid addiction acquisition and relapse.

Oxycodone regulates incision-induced activation of neurotrophic factors and receptors in an acute post-surgery pain rat model

Background

Oxycodone, which is one of the most commonly used opiates in postoperative pain management, has a different affinity for μ-opioid receptors (MOR), κ-opioid receptors (KOR), and δ-opioid receptors (DOR). Accumulating research has suggested that neurotrophins (NTs) are involved in opioid analgesia. In the current exploratory study, we aimed to investigate the underlying mechanisms of the analgesic effects of oxycodone on post-surgery pain in rats and to determine whether neurotrophic factors and receptors were involved in these effects.

Methods

Mechanical and thermal sensitivity tests were used to evaluate the validity of the postoperative pain rat model and to determine the analgesic effect of oxycodone. Quantitative PCR and Western blot analysis were used to detect the changes in the expression of three types of opioid receptors and NTs and their high-affinity receptors in the spinal cord after surgery and oxycodone administration.

Results

Oxycodone showed an analgesic effect on plantar incision (PI)-induced hyperalgesia, especially thermal hyperalgesia. We detected an obvious increase in MOR expression levels but insignificant changes in KOR and DOR levels in the spinal cord after PI. Moreover, we found that oxycodone was able to reverse the increased expression of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor (TrK) A, and TrkB and the decreased expression of NT-3 and TrkC, after PI. Pretreatment with oxycodone also altered the expression of these mediators.

Conclusion

Based on the results, possible underlying mechanisms for the antinociceptive properties of oxycodone in acute postoperative pain include the activation of MOR downstream signaling and the regulation of NTs and receptor expression through attenuation of glial activation and fortification of antinociceptive mediators in the spinal cord. This study may provide new insights into the molecular mechanisms underlying the analgesic action of oxycodone.

Short term exposure to oxycodone alters the survival, proliferation and differentiation of rat embryonic neural stem cell in vitro

As one of several opioids, oxycodone has been widely used, particularly in postoperative analgesia in children and cesarean section. However, the effect of oxycodone on developing brain still remains to be seen. Since there is a link between anesthetics exposure and long-term behavioral or cognitive dysfunction in young children, in the current study, the direct effect of oxycodone on neural stem cells (NSCs) biological behaviors was investigated. After exposed to a high dose of oxycodone (10 μg/mL) for 48 h, NSCs survival and proliferation were significantly reduced, while NSCs apoptosis and differentiation were enhanced. These effects were significantly weaker than that when exposed to same dose of morphine. No significant difference was observed regarding to above biological behaviors when exposed to lower doses (0.1 μg/mL and 1.0 μg/mL) of oxycodone. The antagonist of opioid receptor, nalmefene, successfully reversed the influence of oxycodone. Taken together, our results indicated that short term exposure to oxycodone in low dose might be allowed for developing brain.