Oxycodone/Naloxone: role in chronic pain management, opioid-induced constipation, and abuse deterrence

Oxycodone Extended-Release Capsule Utilization for Pain Management in a Cancer Palliative Care Clinic: A Retrospective Review

Xtampza ER™, an oxycodone extended-release capsule (OERC), was the first long-acting opioid to feature abuse-deterrent properties and various routes of administration without pharmacokinetic alterations. The primary objective of this study was to evaluate changes in reported pain scores after initiation of or rotation to OERC from a previous opioid.  Baseline scores were from patients' outpatient visits immediately before starting OERC and were compared to those at the next two follow-up visits. Secondary objectives identified variables that influenced pain scores. Methods included screening for cancer patients with outpatient OERC prescriptions seen in the palliative care clinic. Eighty-two charts were reviewed with 66 included. Overall mean pain scores at both follow-ups were lower than those at baseline (-0.7 ± 2.1; -1.1 ± 2.4). Results were statistically significant between first and second-reported pain scores versus baseline (p = 0.009; 0.012) but clinically insignificant, defined as a ≥ 2-point change in numeric pain scores. Most patients discontinued OERC at the first or second follow-up (35; 53%), and 12.1% of patients who started OERC were prescribed OERC at the end of the study. There were no significant variables identified to influence pain scores either statistically or clinically. Further studies are needed to determine the long-term efficacy and safety in cancer palliative-care patients.

Opioids in cancer-related pain: current situation and outlook

PURPOSE

Despite progress in treatments, cancer pain remains underestimated, poorly assessed and under-treated. Prescribing strong opioids, because of their specificities, requires precision in management considering their pharmacology but also a clear understanding of recommendations. Some clinicians highlight the risk of addiction, excessive sedation and respiratory depression and their need for information. Our objective in this review is to suggest some clinical guidance for the positioning and daily use of opioids within cancer pain management.

METHODS

Critical reflection based on literature analysis and clinical practice.

RESULTS

Strong opioids may be initiated as soon as pain diagnosis is defined. Factors to consider are pain aetiology, opioid pharmacokinetics and pharmacodynamics, genetic polymorphism, physiology (age, gender, weight and pregnancy), comorbidities (especially renal, hepatic, cardiovascular diseases), chronobiology, environmental factors, medication interference and treatment adherence. Achieving the best-balanced opioid treatment for background pain is complex, mainly due to the variable benefit/risk ratio between individuals and the experience of breakthrough cancer pain. Opioid initiation alongside a dynamic reassessment of pain should be fully integrated into the patient's management to optimise analgesia. The efficacy and safety of a strong opioid treatment need to be re-evaluated and adapted to individuals constantly as it varies over time.

CONCLUSIONS

Cancer pain is multimorphic and permanently changing due to disease evolution, curative treatments and disruptive events (concomitant treatments, pain from associated disease, comorbidities and complications, modifications of the environment). Well-managed opioids are the cornerstone of a complex environment requiring multidisciplinary dynamic assessments integrated into the patient's care pathway.

Prescribing and Administration of Opioid Analgesics in Residents of Aged Care Facilities

Objective:

Optimal pain management in residents requires an understanding of prescribing and administration of opioid analgesics. This study aimed to describe opioid administration for elderly residents in a selection of aged care facilities.

Methods:

A cross-sectional audit of analgesics administration was conducted for all 458 residents of three-aged care facilities on May 1, 2017. The facilities (each ~160 beds) represented a geographically diverse area in Perth, Australia, and varying service levels by nurse practitioners. Data were accessed using the iCare^® platform and transcribed into a customized database. Data were reported descriptively, with relationships between categorical variables examined using the Chi-square analysis. Main outcome measures in the study were the prevalence of administration of opioids compared to that of nonopioid analgesics and no analgesics on the audit date, and characteristics of the opioid prescriptions (the type of prescriber and nursing/care staff involved in the dose administration).

Findings:

Of 458 residents, 95 (20.7%) received an opioid analgesic on the audit date; 231 had also received a nonopioid analgesic. The most common opioid (34 residents) was a brand of oxycodone hydrochloride and naloxone hydrochloride as 10/5 mg tablets. There was no significant tendency for opioid prescribing by classification of the prescriber, nor for any category of nursing/care staff to administer the particular types of analgesics.

Conclusion:

The tendency for prescribing of opioids showed no significant among the prescribers. Finally, the administration of opioids was predominantly by caregivers. This represents the first step in a program of activity to ensure the quality use of potent analgesics in an aged care provider network.

Increases in controlled-release oxycodone utilisation following the subsidy of oxycodone with naloxone formulations: An Australian population-based study

PURPOSE

Despite increasing use of oxycodone/naloxone controlled-release (CR) in Australia, little is known about how it has affected the overall oxycodone CR market since its subsidy in 2011.

METHODS

We used Pharmaceutical Benefits Scheme dispensing claims (2006-2016) and interrupted time series analysis to examine changes in the quarterly rates of dispensing of oral oxycodone CR formulations (oxycodone/naloxone CR and single-ingredient oxycodone CR) and new oxycodone CR treatment episodes. We also performed a retrospective cohort study in a sample of people initiating a new oxycodone CR treatment episode in 2009, 2012/2013, and 2016 to compare opioid utilisation patterns over time.

RESULTS

The subsidy of oxycodone/naloxone CR was associated with a 1.6-fold increase in the growth rate of oxycodone CR dispensing, resulting from rapid uptake of low strength (≤5 mg) oxycodone/naloxone CR. In our cohort of initiators, the number of new oxycodone CR treatment episodes increased 2.1-fold between 2009 and 2016; in 2016, 91.4% of new treatment episodes involved oxycodone/naloxone CR. Comparing 2016 with 2009, we observed an increase in people initiating with a tablet strength less than or equal to 5-mg (risk difference [RD] = 21.1%, 95% CI, 19.9%-22.4%) in people initiating with no other opioid dispensing 90 days prior to initiation (RD = 5.2%, 3.8%-6.6%) and with no further opioid dispensing 90 days after initiation (RD = 8.8%, 7.4%-10.2%).

CONCLUSIONS

After its subsidy, the uptake of low-dose oxycodone/naloxone CR was greater than expected if it were substituting the single-ingredient oxycodone CR, resulting in an expansion of the oxycodone CR market.

A Brief History of the Opioid Epidemic and Strategies for Pain Medicine

The opioid epidemic has resulted from myriad causes and will not be solved by any simple solution. Consequent to a staggering increase in opioid-related deaths in the USA, various governmental inputs and stakeholder strategies have been proposed and implemented with varying success. This article summarizes the history of opioid use and explores the causes for the present day epidemic. Recent trends in opioid-related data demonstrate an almost fourfold increase in overdose deaths from 1999 to 2008. Tragically, opioids claimed over 64,000 lives just last year. Some solutions have undergone legislation, including the limitation of numbers of opioids postsurgery, as well as growing national prevalence of enhanced recovery after surgery protocols which focus on reduced postoperative opioid consumption and shortened hospital stays. Stricter prescribing practices and prescription monitoring programs have been instituted in the recent past. Improvement in abuse deterrent strategies which is a major focus of the Food and Drug Administration (FDA) for all opioid preparations will likely play an important role by increasing the safety of these medications. Future potential strategies such as additional legislative policies, public awareness, and physician education are also detailed in this review.

America's Opioid Epidemic: a Comprehensive Review and Look into the Rising Crisis

PURPOSE OF REVIEW

In the USA, there has been a sharp increase in heroin, prescription opiate, and illicitly manufactured fentanyl abuse with overdoses tripling since the 1990s. Several states have been deemed as "high-burden" abuse states where there is a greater proportion of synthetic opiate use. During the same period that prescription limitations were initially implemented throughout the country, the fentanyl epidemic started nationwide.

RECENT FINDINGS

In the setting of data demonstrating an almost fourfold increase in overdose deaths from 1999 to 2008, states began restricting access to Food and Drug Agency (FDA) approved opioid medications. Another factor further exacerbating the opioid crises is that the cost of all formulations of naloxone has increased significantly over the past several years. In order to combat the opioid epidemic, stricter prescribing practices and prescription-monitoring programs have been instituted. Also, improvements in abuse-deterrent strategies for all opioid preparations can play an important role by increasing the safety of these medications and is a major focus of the FDA.

The Risk of Ischemic Cardio- and Cerebrovascular Events Associated with Oxycodone-Naloxone and Other Extended-Release High-Potency Opioids: A Nested Case-Control Study

INTRODUCTION

In Germany, an extended-release (ER) combination of the high-potency opioid (HPO) oxycodone and the antagonist naloxone was approved in 2006. In recent years, the cardio- and cerebrovascular safety of opioid antagonists and of opioids themselves has been discussed.

OBJECTIVES

The objective of this study was to estimate the risk of major ischemic cardio- and cerebrovascular events in patients receiving ER oxycodone-naloxone compared with those receiving other ER HPOs.

METHODS

We used the German Pharmacoepidemiological Research Database (GePaRD) to conduct a nested case-control study (2006-2011) within a cohort of ER HPO users. Cases were defined as patients hospitalized for acute myocardial infarction (MI) or ischemic stroke (IS). For each case, up to ten controls were selected by risk-set sampling. Using conditional logistic regression, confounder-adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were obtained for the risk of MI/IS associated with (1) current HPO treatment, (2) recent discontinuation, or (3) recent switch of HPO therapy compared with past treatment.

RESULTS

In 309,936 ER HPO users, 12,384 MI/IS events were detected, resulting in a crude incidence rate of 19.48 (95% CI 19.14-19.82) per 1000 person years. A small but significantly elevated aOR was found for morphine (1.12; 95% CI 1.04-1.22) but not for oxycodone-naloxone. Recent discontinuation and recent switch of any ER HPO also had a significant impact on the outcome (aOR 1.12; 95% CI 1.04-1.21 and 1.25; 95% CI 1.03-1.52, respectively).

CONCLUSIONS

Our study does not indicate an association between oxycodone-naloxone and ischemic cardio- or cerebrovascular events. However, our findings do suggest that every change in ER HPO therapy should be conducted with caution.

Efficacy and safety of oxycodone/naloxone as add-on therapy to gabapentin or pregabalin for the management of chemotherapy-induced peripheral neuropathy in Korea

AIMS

To investigate the efficacy and safety of oxycodone/naloxone in patients with chemotherapy-induced peripheral neuropathy (CIPN) inadequately controlled with pregabalin or gabapentin.

METHODS

This 4-week, multicenter, interventional, single-arm phase IV study included 72 Korean patients with CIPN inadequately controlled with pregabalin or gabapentin (Numeric Rating Scale 0-10; NRS ≥4 at baseline). In addition to pregabalin or gabapentin at existing doses, patients received 20/10 mg/day oxycodone/naloxone (up-titrated to 80/40 mg/day as needed). The primary endpoint was change in NRS score after 4 weeks. Secondary endpoints included Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-NTX) scores and safety assessments.

RESULTS

The mean ± standard deviation (SD) dose of oxycodone/naloxone was 23.3 ± 7.5 mg/day. At week 4, NRS score reduction was 1.29 ± 1.84 points (21.4% reduction; P < 0.0001). Patients on taxane-based chemotherapy experienced a significantly smaller mean change in NRS score at week 4 compared to patients on other chemotherapy (-0.63 ± 1.54 [n = 30] vs. -1.83 ± 1.00 [n = 36]; P = 0.0072). Although there were no significant changes in FACT/GOG-NTX total scores, improvements were observed in the neurotoxicity subscale measuring numbness/tingling of hands (mean ± SD change: -0.27 ± 1.04; P = 0.0427) and feet (-0.60 ± 1.09; P < 0.0001). Forty-two (58.3%) patients reported adverse events. There were no clinically significant changes in laboratory tests or vital signs.

CONCLUSION

Oxycodone/naloxone added to pregabalin or gabapentin provided additional pain relief and symptom control in Korean patients with CIPN, without clinically significant safety concerns.

Efficacy and safety of controlled-release oxycodone/naloxone versus controlled-release oxycodone in Korean patients with cancer-related pain: a randomized controlled trial

BACKGROUND

Controlled-release oxycodone/naloxone (OXN-CR) maintains the effect of opioid-induced analgesia through oxycodone while reducing the occurrence rate of opioid-induced constipation through naloxone. The present study was designed to assess the non-inferiority of OXN-CR to controlled-release oxycodone (OX-CR) for the control of cancer-related pain in Korean patients.

METHODS

In this randomized, open-labeled, parallel-group, phase IV study, we enrolled patients aged 20 years or older with moderate to severe cancer-related pain [numeric rating scale (NRS) pain score ≥4] from seven Korean oncology/hematology centers. Patients in the intention-to-treat (ITT) population were randomized (1:1) to OXN-CR or OX-CR groups. OXN-CR was administered starting at 20 mg/10 mg per day and up-titrated to a maximum of 80 mg/40 mg per day for 4 weeks, and OX-CR was administered starting at 20 mg/day and up-titrated to a maximum of 80 mg/day for 4 weeks. The primary efficacy endpoint was the change in NRS pain score from baseline to week 4, with non-inferiority margin of -1.5. Secondary endpoints included analgesic rescue medication intake, patient-reported change in bowel habits, laxative intake, quality of life (QoL), and safety assessments.

RESULTS

Of the ITT population comprising 128 patients, 7 with missing primary efficacy data and 4 who violated the eligibility criteria were excluded from the efficacy analysis. At week 4, the mean change in NRS pain scores was not significantly different between the OXN-CR group (n = 58) and the OX-CR group (n = 59) (-1.586 vs. -1.559, P = 0.948). The lower limit of the one-sided 95% confidence interval (-0.776 to 0.830) for the difference exceeded the non-inferiority margin (P < 0.001). The OXN-CR and OX-CR groups did not differ significantly in terms of analgesic rescue medication intake, change in bowel habits, laxative intake, QoL, and safety assessments.

CONCLUSIONS

OXN-CR was non-inferior to OX-CR in terms of pain reduction after 4 weeks of treatment and had a similar safety profile. Studies in larger populations of Korean patients with cancer-related pain are needed to further investigate the effectiveness of OXN-CR for long-term pain control and constipation alleviation. Trial registration ClinicalTrials.gov NCT01313780, registered March 8, 2011.

Efficacy and tolerability balance of oxycodone/naloxone and tapentadol in chronic low back pain with a neuropathic component: a blinded end point analysis of randomly selected routine data from 12-week prospective open-label observations

Objective

To evaluate the benefit–risk profile (BRP) of oxycodone/naloxone (OXN) and tapentadol (TAP) in patients with chronic low back pain (cLBP) with a neuropathic component (NC) in routine clinical practice.

Methods

This was a blinded end point analysis of randomly selected 12-week routine/open-label data of the German Pain Registry on adult patients with cLBP-NC who initiated an index treatment in compliance with the current German prescribing information between 1st January and 31st October 2015 (OXN/TAP, n=128/133). Primary end point was defined as a composite of three efficacy components (≥30% improvement of pain, pain-related disability, and quality of life each at the end of observation vs baseline) and three tolerability components (normal bowel function, absence of either central nervous system side effects, and treatment-emergent adverse event [TEAE]-related treatment discontinuation during the observation period) adopted to reflect BRP assessments under real-life conditions.

Results

Demographic as well as baseline and pretreatment characteristics were comparable for the randomly selected data sets of both index groups without any indicators for critical selection biases. Treatment with OXN resulted formally in a BRP noninferior to that of TAP and showed a significantly higher primary end point response vs TAP (39.8% vs 25.6%, odds ratio: 1.93; P=0.014), due to superior analgesic effects. Between-group differences increased with stricter response definitions for all three efficacy components in favor of OXN: ≥30%/≥50%/≥70% response rates for OXN vs TAP were seen for pain intensity in 85.2%/67.2%/39.1% vs 83.5%/54.1%/15.8% (P= ns/0.031/<0.001), for pain-related disability in 78.1%/64.8%/43.8% vs 66.9%/50.4%/24.8% (P=0.043/0.018/0.001), and for quality of life in 76.6%/68.0%/50.0% vs 63.9%/54.1%/34.6% (P=0.026/0.022/0.017). Overall, OXN vs TAP treatments were well tolerated, and proportions of patients who either maintained a normal bowel function (68.0% vs 72.2%), reported no central nervous system side effects (91.4% vs 89.5%), or completed the 12-week evaluation period without any TEAE-related treatment discontinuations (93.0% vs 92.5%) were similar for both index medications (P= ns for each comparison).

Conclusion

In daily practice, the BRP of OXN proved to be noninferior to that of TAP in patients with cLBP-NC, but showed a superior efficacy if stricter analgesic response definitions were evaluated.

Opioid-induced constipation: rationale for the role of norbuprenorphine in buprenorphine-treated individuals

Buprenorphine and buprenorphine–naloxone fixed combinations are effective for managing patients with opioid dependence, but constipation is one of the most common side effects. Evidence indicates that the rate of constipation is lower when patients are switched from sublingual buprenorphine–naloxone tablets or films to a bilayered bioerodible mucoadhesive buccal film formulation, and while the bilayered buccal film promotes unidirectional drug flow across the buccal mucosa, the mechanism for the reduced constipation is unclear. Pharmacokinetic simulations indicate that chronic dosing of sublingually administered buprenorphine may expose patients to higher concentrations of norbuprenorphine than buprenorphine, while chronic dosing of the buccal formulation results in higher buprenorphine concentrations than norbuprenorphine. Because norbuprenorphine is a potent full agonist at mu-opioid receptors, the differences in norbuprenorphine exposure may explain the observed differences in treatment-emergent constipation between the sublingual formulation and the buccal film formulation of buprenorphine–naloxone. To facilitate the understanding and management of opioid-dependent patients at risk of developing opioid-induced constipation, the clinical profiles of these formulations of buprenorphine and buprenorphine-naloxone are summarized, and the incidence of treatment-emergent constipation in clinical trials is reviewed. These data are used to propose a potential role for exposure to norbuprenorphine, an active metabolite of buprenorphine, in the pathophysiology of opioid-induced constipation.

Opioid-induced constipation

Opioid-induced constipation (OIC) is a very troublesome, difficult to manage and a nearly universal complication of chronic opioid use to control pain associated with advanced illness. Some studies have reported that OIC is so intolerable in some patients that they skip their opioid medications and bear pain instead of OIC. Laxatives have commonly been used as a prophylaxis and treatment of OIC but they are frequently ineffective because the commonly available laxatives do not target the underlying mechanism of OIC, which is the blockade of peripheral mu-receptors. Recently, there have been a number of advances in the treatment of OIC, which any physician involved with opioid-prescribing discipline should be aware of. This review will update the new options and strategies available for treating OIC along with the relevant clinical trials. Finally, this review also provides a recommendation on the preferred way to approach a patient with OIC in the modern era as well as highlight on the importance of doctor-patient communication in this setting.

Gender difference in prescription opioid abuse: A focus on oxycodone and hydrocodone

Several data gathered in the last decade indicate an increase of abuse of prescription opioid drugs oxycodone (OXY) and hydrocodone (HYDRO) in women. However, to date there are no conclusive evidences investigating the gender-dependent abuse liability of prescription opioids. This study aims to supply a specific focus on women's data through a selective summary of the literature analyzing gender differences in the pharmacokinetic and pharmacodynamic dimension of OXY and HYDRO. Findings from this study suggest that the majority of OXY and HYDRO pharmacokinetic and pharmacodynamic effects do not differ according to gender, though confirming a significant difference in the incidence of adverse effects as demonstrated by the increased gastrointestinal adverse reactions in female subjects. Although the majority of recent clinical studies include an equal number of female and male subjects, the main outcome parameters do not relate specifically to gender differences. Due to the gender influence in activity of CYP3A4 and its crucial role in metabolism of both OXY than HYDRO, we suggest that assessing pharmacokinetic and pharmacodynamic interactions in clinical studies may be useful to clarify the effect of the higher CYP3A4 activity in female in relation to CYP2D6 genotype. Overall, considering the paucity of data regarding gender differences in European Union, this work highlights that impact of new abuse deterrent formulations should be assessed with a special focus on data concerning female subjects.

Expression and physiology of opioid receptors in the gastrointestinal tract

PURPOSE OF REVIEW

Stimulation of opioid receptors elicits analgesic effect not only in the central nervous system, but also in the gastrointestinal tract, where a high concentration of opioid receptors can be found within the enteric nervous system as well as muscular and immune cells. Along with antinociception, opioid receptors in the stomach and intestine relay signals crucial for secretory and motor gastrointestinal function.

RECENT FINDINGS

The review focuses on the utility of opioid receptor antagonists, which is generally contributing to the management of postoperative ileus and opioid bowel dysfunction in chronic pain patients nonetheless, opioid receptor antagonists can also be useful in the treatment of irritable bowel syndrome and chronic idiopathic constipation. The study also discusses several antidiarrheal opioid agonists, as well as opioids and opioid mimetics encompassing the concept of ligand-biased agonism and truncated opioid receptor splice variants.

SUMMARY

Good understanding of the localization and the role of opioid receptors is vital for regulation of various pathophysiological processes in the gastrointestinal tract and may simultaneously provide a tempting approach in eliminating adverse effects related to centrally acting opioids.

Endogenous opiates and behavior: 2014

This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants). This paper is the thirty-seventh consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2014 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (endogenous opioids and receptors), and the roles of these opioid peptides and receptors in pain and analgesia (pain and analgesia); stress and social status (human studies); tolerance and dependence (opioid mediation of other analgesic responses); learning and memory (stress and social status); eating and drinking (stress-induced analgesia); alcohol and drugs of abuse (emotional responses in opioid-mediated behaviors); sexual activity and hormones, pregnancy, development and endocrinology (opioid involvement in stress response regulation); mental illness and mood (tolerance and dependence); seizures and neurologic disorders (learning and memory); electrical-related activity and neurophysiology (opiates and conditioned place preferences (CPP)); general activity and locomotion (eating and drinking); gastrointestinal, renal and hepatic functions (alcohol and drugs of abuse); cardiovascular responses (opiates and ethanol); respiration and thermoregulation (opiates and THC); and immunological responses (opiates and stimulants).

Prolonged-release oxycodone-naloxone for treatment of severe pain in patients with Parkinson's disease (PANDA): a double-blind, randomised, placebo-controlled trial

BACKGROUND

Pain is a common non-motor symptom of Parkinson's disease. We investigated the analgesic efficacy of prolonged-release oxycodone-naloxone (OXN PR) in patients with Parkinson's disease and chronic, severe pain.

METHODS

We did this phase 2 study in 47 secondary care centres in the Czech Republic, Germany, Hungary, Poland, Romania, Spain, and the UK. We enrolled patients with Hoehn and Yahr Stage II-IV Parkinson's disease, at least one type of severe pain, and an average 24-h pain score of at least 6 (assessed on an 11-point rating scale from 0=no pain to 10=pain as bad as you can imagine). Participants were randomly assigned (1:1) with a validated automated system (block size four) to either oral OXN PR or placebo for 16 weeks (starting dose oxycodone 5 mg, naloxone 2·5 mg, twice daily). Patients and investigators were masked to treatment assignment. The primary endpoint was average 24-h pain score at 16 weeks in the full analysis population. This study is registered with EudraCT (2011-002901-31) and ClinicalTrials.gov (NCT01439100).

FINDINGS

We enrolled 202 patients; 93 were assigned to OXN PR and 109 to placebo; the full analysis population consisted of 88 patients versus 106 patients. Least squares mean average 24-h pain score at 16 weeks in the full analysis population was 5·0 (95% CI 4·5 to 5·5) in the OXN PR group versus 5·6 (5·1 to 6·0) in the placebo group (difference -0·6, 95% CI -1·3 to 0·0; p=0·058). Similar proportions of patients in each group had adverse events (60/92 [65%] vs 76/109 [70%]), treatment-related adverse events (52/92 [57%] vs 62/109 [57%]), and serious adverse events (5/92 [5%] vs 7/109 [6%]). Treatment-related nausea was more common in the OXN PR group than in the placebo group (16/92 [17%] vs 10/109 [9%]), as was treatment-related constipation (16/92 [17%] vs 6/109 [6%]).

INTERPRETATION

The primary endpoint, based on the full analysis population at week 16, was not significant. Nonetheless, the results of this study highlight the potential efficacy of OXN PR for patients with Parkinson's disease-related pain and might warrant further research on OXN PR in this setting.

FUNDING

Mundipharma Research.

Estimating the health care burden of prescription opioid abuse in five European countries

Background

Opioid abuse, including abuse of prescription opioids (“RxOs”) and illicit substances like heroin, is a serious public health issue in Europe. Currently, there is limited data on the magnitude of RxO abuse in Europe, despite increasing public and scientific interest in the issue. The purpose of this study was to use the best-available data to derive comparable estimates of the health care burden of RxO abuse in France, Germany, Italy, Spain, and the United Kingdom (EU5).

Methods

Published data on the prevalence of problem opioid use and the share of opioid abuse patients reporting misuse of non-heroin opioids were used to estimate the prevalence of RxO abuse in the EU5 countries. The costs of RxO abuse were calculated by applying published estimates of the incremental health care costs of opioid abuse to country-specific estimates of the costs of chronic pain conditions. These estimates were input into an economic model that quantified the health care burden of RxO abuse in each of the EU5 countries. Sensitivity analyses examined key assumptions.

Results

Based on best-available current data, prevalence estimates of RxO abuse ranged from 0.7 to 13.7 per 10,000 individuals across the EU5 countries. Estimates of the incremental health care costs of RxO abuse ranged from €900 to €2,551 per patient per year. The annual health care cost burden of RxO abuse ranged from €6,264 to €279,927 per 100,000 individuals across the EU5 countries.

Conclusion

This study suggests that RxO abuse imposes a cost burden on health systems in the five largest European countries. The extent of RxO abuse in Europe should be monitored given the potential for change over time. Continued efforts should be made to collect reliable data on the prevalence and costs of RxO abuse in Europe to facilitate an accurate characterization of the extent of this potentially growing problem.

Oxycodone/Naloxone PR: A Review in Severe Refractory Restless Legs Syndrome

An oral, fixed-dose combination of prolonged-release (PR) oxycodone with PR naloxone (Targin(®), Targiniq(®), Targinact(®); hereafter referred to as oxycodone/naloxone PR) is approved in Europe for the second-line symptomatic treatment of patients with severe to very severe idiopathic restless legs syndrome (RLS), after failure of dopaminergic therapy. Coadministration of naloxone represents a targeted approach to counteracting opioid-induced bowel dysfunction without compromising therapeutic efficacy; because of its very low oral bioavailability, naloxone blocks the action of oxycodone at opioid receptors locally in the gut. The efficacy of oxycodone/naloxone PR in patients with severe RLS inadequately controlled by previous (mainly dopaminergic) treatment has been demonstrated in RELOXYN, a 12-week, randomized, double-blind study with a 40-week open-label extension. In this pivotal study, oxycodone/naloxone PR significantly improved RLS symptoms compared with placebo from week 2 onwards; a beneficial effect of oxycodone/naloxone PR was maintained through 1 year of treatment. Furthermore, improvements in RLS symptoms in oxycodone/naloxone PR recipients were accompanied by similarly sustained improvements in disease-specific quality of life and subjective sleep variables. Oxycodone/naloxone PR was generally well tolerated, with a treatment-related adverse event profile (e.g. gastrointestinal disorders, CNS disorders, fatigue and pruritus) that was consistent with that expected for opioid therapy. Notably, there were no confirmed cases of augmentation among oxycodone/naloxone PR recipients throughout the course of the study. Results from the well-designed RELOXYN trial have thus demonstrated the value of oxycodone/naloxone PR as a second-line therapy for severe refractory RLS; further investigation of this combination product as a first-line treatment for severe RLS is now warranted.

Naloxegol , a new drug for the treatment of opioid-induced constipation

INTRODUCTION

With increasing chronic opioid use, opioid-induced constipation (OIC) is becoming a relevant clinical challenge. Presently, only few treatments have been demonstrated to be more effective than placebo in treating OIC but most of them have a restricted clinical application because of side effects. Naloxegol , an orally administered, peripherally acting, μ-opioid receptor antagonist (PAMORA), was developed for the treatment of OIC.

AREA COVERED

This review summarizes published information and presentations at meetings on the effects of naloxegol in OIC. Pharmacodynamic studies have demonstrated that naloxegol inhibits gastrointestinal opioid effects while preserving central analgesic actions. Phase II and Phase III studies in patients with non-cancer OIC have confirmed the efficacy of naloxegol to inhibit OIC, and the most consistent efficacy was seen with the 25 mg dose once daily. Adverse events were mainly gastrointestinal in origin and usually transient and mild. There were no signs of opioid withdrawal in the studies. Safety and tolerability were also shown in a long-term safety study. Regulatory authorities have recently approved the use of naloxegol in OIC.

EXPERT OPINION

Naloxegol is the first approved, orally available PAMORA. The drug has the potential to substantially improve management of OIC patients.