Opioid-induced bowel dysfunction: pathophysiology and management

Peripherally acting μ-opioid antagonist for the treatment of opioid-induced constipation: Systematic review and meta-analysis

BACKGROUND AND AIM

Opioid-induced constipation (OIC) is a frequent adverse event (AE) that impairs patients' quality of life (QOL). Peripherally acting μ-opioid receptor antagonists (PAMORAs) have been recognized as a treatment option for OIC, but the effect consistent across the studies has not been evaluated.

METHODS

We conducted a quantitative meta-analysis to explore the efficacy of PAMORA for OIC (registered with PROSPERO: CRD42018085298). We systematically searched randomized controlled trials (RCTs) in Medline, Embase, and Central databases. Change from baseline in spontaneous bowel movements, pooled proportion of responders, QOL, and AEs were calculated and compared with results in placebo cases.

RESULTS

We included 31 RCTs with 7849 patients. A meta-analysis revealed that patients under PAMORA therapy had considerably improved spontaneous bowel movement from baseline compared with those given placebo (20 RCTs; mean difference, 1.43; 95% confidence interval [CI], 1.18-1.68; n = 5622) and more responded (21 RCTs; risk ratio [RR], 1.81; 95% CI, 1.55-2.12; n = 4821). Moreover, QOL of patients receiving PAMORA was significantly better (8 RCTs; mean difference, -0.22; 95% CI, -0.28 to -0.17; n = 2884). AEs were increased significantly in the PAMORA group (26 RCTs; RR, 1.10; 95% CI, 1.06-1.15; n = 7715), especially in gastrointestinal disorders, whereas serious AEs were not significant (17 RCTs; RR, 1.04; 95% CI, 0.85-1.28; n = 5890).

CONCLUSION

Peripherally acting μ-opioid receptor antagonist has been shown to be effective and durable for patients with OIC and is the only drug with confirmed evidence in meta-analysis. The possibility of publication bias was the limitation of this study.

Self-Rated Physical Health and Unmet Healthcare Needs among Swedish Patients in Opioid Substitution Treatment

Background

Individuals with opioid dependence are at increased risk of deteriorating health due to the lifestyle connected to heroin use. Barriers surrounding the healthcare system seem to hinder patients to seek help through conventional healthcare, even after entering opioid substitution treatment (OST), resulting in a high level of unmet healthcare needs. However, this field is still unexplored, with only a few studies focusing on general health within this population. The first step, in order to provide suitable and accessible primary healthcare, is to assess the extent of physical symptoms and unmet healthcare needs within the OST population, which, to this point, has been sparsely studied.

Aim

To assess OST patients' self-rated physical health and healthcare seeking behaviour.

Methods

Two-hundred and eighteen patients from four different OST sites answered a questionnaire regarding physical health and healthcare seeking.

Results

Patients in OST have a high degree of physical symptoms and a high degree of unmet healthcare needs. Sixty-six percent reported suffering from musculoskeletal pain. Fifty-six percent reported gastrointestinal symptoms. Genital problems and airway symptoms were reported by 47%, respectively, and dental problems were reported by 69% of the respondents. General unmet healthcare needs were reported by 82%. Musculoskeletal pain was positively correlated with having an unstable housing situation (AOR 4.26 [95% CI 1.73-10.48]), negatively correlated with male sex (AOR 0.45 [95% CI 0.22-0.91]), and positively correlated with age (AOR 1.04 [95% CI 1.01-1.07]). No statistically significant correlates of respiratory, gastrointestinal, genital, or dental symptoms were found.

Conclusion

Patients in OST carry a heavy burden of physical symptoms and unmet healthcare needs, potentially due to societal barriers. Patients' frequent visits to the OST clinics offer a unique opportunity to build a base for easily accessible on-site primary healthcare.

Opioid-induced constipation: a narrative review of therapeutic options in clinical management

Pain therapy often entails gastrointestinal adverse events. While opioids are effective drugs for pain relief, the incidence of opioid-induced constipation (OIC) varies greatly from 15% to as high as 81%. This can lead to a significant impairment in quality of life, often resulting in discontinuation of opioid therapy. In this regard, a good doctor-patient relationship is especially pivotal when initiating opioid therapy. In addition to a detailed history of bowel habits, patient education regarding the possible gastrointestinal side effects of the drugs is crucial. In addition, the bowel function must be regularly evaluated for the entire duration of treatment with opioids. Furthermore, if the patient has preexisting constipation that is well under control, continuation of that treatment is important. In the absence of such history, general recommendations should include sufficient fluid intake, physical activity, and regular intake of dietary fiber. In patients of OIC with ongoing opioid therapy, the necessity of opioid use should be critically reevaluated in terms of an with acceptable quality of life, particularly in cases of non-cancer pain. If opioids must be continued, lowering the dose may help, as well as changing the type of opioid. If these measures do not suffice, the next step for persistent OIC is the administration of laxatives. If these are ineffective as well, treatment with peripherally active μ-opioid receptor antagonists should be considered. Enemas and irrigation are emergency measures, often used as a last resort.

Opioid-induced bowel dysfunction: suggestions from a multidisciplinary expert Board

Constipation, one of the adverse effects of opioid therapy with a major impact on quality of life, is still an unmet need for cancer patients, particularly those with an advanced and progressive disease, and for non-cancer patients chronically treated with opioids. The awareness of this condition is poor among healthcare providers, despite the recent publication of guidelines and consensus conferences. An early multidisciplinary approach of opioid-induced bowel dysfunction (OIBD), based on available therapies of proven effectiveness, could support clinicians in managing this condition, thus increasing patients’ adherence to pain therapy. Several Italian experts involved in the management of patients suffering from pain (anaesthesia pain therapy, oncology, haematology, palliative care, gastroenterology) joined in a Board in order to draw up an expert opinion on OIBD. The most frequent and still unsolved issues in this field were examined, including a more comprehensive definition of OIBD, the benefits of early intervention to prevent its occurrence and the most appropriate use of peripherally acting mu-opioid receptor antagonists (PAMORAs). The use of the recently introduced PAMORA naloxegol was analysed, in light of the current literature. The Board proposed a solution for each open issue in the form of recommendations, integrated with the contribution of representatives from different disciplines and often accompanied by procedural algorithms immediately usable and applicable in daily clinical practice. Safety and quality of life of the patient suffering from pain and from the adverse effects of pain therapies have been the mainstays of this expert opinion, in cooperation with general practitioners and caregivers.

Mechanism-based pain management in chronic pancreatitis - is it time for a paradigm shift?

INTRODUCTION

Pain is the most common symptom in chronic pancreatitis and treatment remains a challenge. Management of visceral pain, in general, is only sparsely documented, and treatment in the clinic is typically based on empirical knowledge from somatic pain conditions. This may be problematic, as many aspects of the neurobiology differ significantly from somatic pain, and organs such as the gut and liver play a major role in tolerability to analgesics. On the other hand, clinical awareness and new methods for quantitative assessment of pain mechanisms, will likely increase our understanding of the visceral pain system and guide more individualized pain management. Areas covered: This review includes an overview of known pain mechanisms in chronic pancreatitis and how to characterize them using quantitative sensory testing. The aim is to provide a mechanism-oriented approach to analgesic treatment, including treatment of psychological factors affecting pain perception and consideration of side effects in the management plan. Expert opinion: A mechanism-based examination and profiling of pain in chronic pancreatitis will enable investigators to provide a well-substantiated approach to effective management. This mechanism-based, individualized regime will pave the road to better pain relief and spare the patient from unnecessary trial-and-error approaches and unwanted side effects.

Incorporating the patient perspective in the study of rare bone disease: insights from the osteogenesis imperfecta community

There is limited research which examines health concerns of individuals with osteogenesis imperfecta (OI). Discussion groups with leaders of the adult OI community identified a broad range of medical priorities beyond fractures and brittle bones. Our work underscores the need to include patient-reported outcomes in rare bone disease research.

INTRODUCTION

Osteogenesis imperfecta (OI) is a rare genetic disorder affecting collagen protein leading to brittle bones and a number of other medical complications. To date, there is limited research which examines the life-long process of aging with this rare disease, much less the perspective of individuals with OI.

METHODS

In order to explore and prioritize health concerns that adults with OI feel have been inadequately addressed in health care and research, investigators held discussions with leaders from the global adult OI community. The meetings were held in August 2017 at the 13th International Conference on OI in Oslo, Norway as part of the preconference seminar "Patient Participation in OI Research". Investigators were part of the Brittle Bone Disease Consortium (BBDC), a multicenter research program devoted to the study of OI, and their focus was on patient-reported outcomes (PRO).

RESULTS

Participants noted that while fractures and brittle bones are the most common feature of OI, a number of body systems are under-studied in this disorder. They particularly emphasized breathing, hearing, and the effects of aging as primary concerns that researchers and physicians may not fully understand or address. Other areas included pain, gastrointestinal problems, mental health, nutrition, menopause/pregnancy, and basilar invagination. Participants also emphasized that they must be informed of study results. They underscored that outcome measures incorporated into future drug trials must look beyond fractures and consider the whole patient.

CONCLUSIONS

This work will help guide the incorporation of PROs into the next phase of the BBDC Natural History Study of OI and underscores the importance of including PROs in the study of rare diseases.

Pathophysiology and management of opioid-induced constipation: European expert consensus statement

BACKGROUND

Opioid-induced bowel dysfunction is a complication of opioid therapy, in which constipation is the most common and problematic symptom. However, it is frequently under-recognised and thus effective management is often not instituted despite a number of treatment options.

OBJECTIVE

The central objective of this study is to provide a summary of the pathophysiology and clinical evaluation of opioid-induced constipation and to provide a pragmatic management algorithm for day-to-day clinical practice.

METHODS

This summary and the treatment algorithm is based on the opinion of a European expert panel evaluating current evidence in the literature.

RESULTS

The pathophysiology of opioid-induced constipation is multi-faceted. The key aspect of managing opioid-induced constipation is early recognition. Specific management includes increasing fluid intake, exercise and standard laxatives as well as addressing exacerbating factors. The Bowel Function Index is a useful way of objectively evaluating severity of opioid-induced constipation and monitoring response. Second-line treatments can be considered in those with recalcitrant symptoms, which include gut-restricted or peripherally acting mu-opioid receptor antagonists. However, a combination of interventions may be needed.

CONCLUSION

Opioid-induced constipation is a common, yet under-recognised and undertreated, complication of opioid therapy. We provide a pragmatic step-wise approach to opioid-induced constipation, which should simplify management for clinicians.

The role of oxycodone/naloxone in the management of patients with pain and opioid-induced constipation

INTRODUCTION

Common opioid adverse effects (AE) of the gastrointestinal tract include opioid-induced constipation (OIC) and opioid-induced bowel dysfunction (OIBD) with traditional laxatives being of limited efficacy, having AEs and not addressing the pathophysiology of OIC or OIBD. Targeted treatment comprises of PAMORA (peripherally acting mu-opioid receptor antagonists) and a combination of an opioid receptor agonist with its antagonist, namely prolonged-release oxycodone with prolonged-release naloxone (OXN) tablets at a fixed ratio of 2:1. Oxycodone provides analgesia, whereas naloxone prevents binding or displaces it from opioid receptors located in the gut wall. Areas covered: The authors review the role of OXN in the management of patients with pain and OIC. A literature search was performed using the search terms 'oxycodone/naloxone' and 'opioid-induced constipation' using the PubMed database up to October 2018. Expert opinion: OXN delivers analgesia comparable (or superior versus placebo and in observational studies) to oxycodone alone and other opioids with a limited or decreased disturbing effect on bowel function. OXN in daily doses of up to 160 mg/80 mg provides effective analgesia with little negative impact on bowel function. OXN may be successfully used in patients with chronic pain, to prevent or treat symptoms of OIC and OIBD.

MRI analysis of fecal volume and dryness: Validation study using an experimental oxycodone-induced constipation model

BACKGROUND

Opioids are known to affect gastrointestinal motility, but their effect on fluid absorption and secretion is poorly understood in humans.

PURPOSE

To investigate the effect of oxycodone on colonic fecal volume and stool dryness by using a novel MRI-based technique.

STUDY TYPE

Prospective, randomized, double-blinded, crossover study.

SUBJECTS

Twenty-five healthy male volunteers (median age: 24 years [range: 21-56]; mean body mass index [BMI]: 23.9 kg/m² [range: 22.9-25.0]) without known gastrointestinal disease.

FIELD STRENGTH/SEQUENCE

T₂ -weighted and two-point Dixon MRI scans of the abdomen at 1.5 T.

ASSESSMENT

Subjects were treated for 5 days with prolonged-release oxycodone or a placebo. Imaging was performed on the first and last study day in each period. Images of the colon were analyzed with semiautomatic k-means-based segmentation software. Regional colonic fecal volumes were quantified excluding gas volume and colon wall. Two-point Dixon and T₂ -weighted MRI signal intensity were assessed as a proxy of colonic stool dryness. Data were obtained in a previously reported study.

STATISTICAL TESTS

Intraclass correlation coefficients were used to test the reliability of measurements between days, while repeated measures mixed models were applied to test treatment effects.

RESULTS

After oxycodone treatment, total colonic fecal volume was significantly increased compared with placebo (mean change 100 mL vs. -13 mL; P = 0.001), with the largest increase (24%) observed in the ascending colon/cecum (P = 0.001). Dixon signal increased (less water in colon content) after oxycodone treatment compared with placebo (mean 0.09 vs. -0.02; P < 0.001). T₂ -weighted signal decreased (less water in colon content) after oxycodone treatment compared with placebo (mean -0.03 vs. 0.03; P = 0.002).

DATA CONCLUSION

The 5-day oxycodone treatment increased colonic fecal volume and increased stool dryness compared with placebo. This imaging-based method for noninvasive analysis of colon content has the potential to characterize gastrointestinal symptoms in general, such as in constipation.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 1 J. Magn. Reson. Imaging 2019;50:733-745.

The pharmacokinetics and pharmacodynamics of intravenous hydromorphone in horses

OBJECTIVE

Describe the pharmacokinetics and pharmacodynamics of intravenous hydromorphone in healthy horses.

STUDY DESIGN

Masked, randomized, cross-over, Latin square design.

ANIMALS

A group of eight healthy adult horses METHODS: Horses were administered each of four treatments with an 8 day washout. Treatments groups included intravenous hydromorphone 0.02 mg kg^-1 (LD), 0.04 mg kg^-1 (MD), 0.08 mg kg^-1 (HD) and saline (P). Blood samples for hydromorphone analysis were obtained for 24 hours after treatment. Plasma hydromorphone was quantified and pharmacokinetic parameters were determined using non-compartmental analysis. Pharmacodynamic data collected for 24 hours after treatment included thermal nociceptive threshold, heart rate (HR), respiratory rate (f_R) and rectal temperature, and analyzed using mixed-effects linear models.

RESULTS

Mean (± standard deviation) hydromorphone terminal half-life (t_1/2), systemic clearance and apparent volume of distribution at steady state (Vd_ss) were 18.1 ± 18.6, 34.0 ± 12.8, and 41.3 ± 32.5 minutes, 66.6 ± 5.3, 550.0 ± 76.4, and 92.7 ± 13.9 mL kg^-1 minute^-1, and 1118 ± 369, 1460 ± 325 and 2242 ± 950 mL kg^-1 for treatments LD, MD and HD, respectively. Thermal threshold increased significantly compared to baseline for all treatments for up to 12 hours. HR was elevated above baseline in treatments LD, MD and HD, extending to 30, 15 and 105 minutes after treatment, respectively. Respiratory rate was elevated above baseline in treatments MD and HD from 30 to 195 minutes and from 45 to 480 minutes after treatment, respectively. Temperature was elevated above baseline in treatment HD until 255 minutes after treatment.

CONCLUSIONS

Hydromorphone exhibited a short t_1/2, rapid clearance and large Vd_ss in horses. It also provided a dose-dependent increase in thermal threshold with associated increases in HR, f_R and rectal temperature.

CLINICAL RELEVANCE

Hydromorphone 0.04 mg kg^-1 provided clinically relevant thermal antinociception with minimal adverse effects.

Implementation of a Risk-Stratified Opioid and Benzodiazepine Weaning Protocol in a Pediatric Cardiac ICU

OBJECTIVES

Opioids and benzodiazepines are commonly used to provide analgesia and sedation for critically ill children with cardiac disease. These medications have been associated with adverse effects including delirium, dependence, withdrawal, bowel dysfunction, and potential neurodevelopmental abnormalities. Our objective was to implement a risk-stratified opioid and benzodiazepine weaning protocol to reduce the exposure to opioids and benzodiazepines in pediatric patients with cardiac disease.

DESIGN

A prospective pre- and postinterventional study.

PATIENTS

Critically ill patients less than or equal to 21 years old with acquired or congenital cardiac disease exposed to greater than or equal to 7 days of scheduled opioids ± scheduled benzodiazepines between January 2013 and February 2015.

SETTING

A 24-bed pediatric cardiac ICU and 21-bed cardiovascular acute ward of an urban stand-alone children's hospital.

INTERVENTION

We implemented an evidence-based opioid and benzodiazepine weaning protocol using educational and quality improvement methodology.

MEASUREMENTS AND MAIN RESULTS

One-hundred nineteen critically ill children met the inclusion criteria (64 post intervention, 55 pre intervention). Demographics and risk factors did not differ between groups. Patients in the postintervention period had shorter duration of opioids (19.0 vs 30.0 d; p < 0.01) and duration of benzodiazepines (5.3 vs 22.7 d; p < 0.01). Despite the shorter duration of wean, there was a decrease in withdrawal occurrence (% Withdrawal Assessment Tool score ≥ 4, 4.9% vs 14.1%; p < 0.01). There was an 8-day reduction in hospital length of stay (34 vs 42 d; p < 0.01). There was a decrease in clonidine use (14% vs 32%; p = 0.02) and no change in dexmedetomidine exposure (59% vs 75%; p = 0.08) in the postintervention period.

CONCLUSIONS

We implemented a risk-stratified opioid and benzodiazepine weaning protocol for critically ill cardiac children that resulted in reduction in opioid and benzodiazepine duration and dose exposure, a decrease in symptoms of withdrawal, and a reduction in hospital length of stay.

Effect of perioperative infusion of Dexmedetomidine combined with Sufentanil on quality of postoperative analgesia in patients undergoing laparoscopic nephrectomy: a CONSORT-prospective, randomized, controlled trial

Background

Postoperative pain is one of the most common symptoms after surgery, which brings physical discomfort to patients. In addition, it may cause a series of complications, and even affect the long-term quality of life. The purpose of this prospective, randomized, double-blinded, controlled trial is to investigate the efficacy and safety of dexmedetomidine combined with sufentanil to attenuate postoperative pain in patients after laparoscopic nephrectomy.

Methods

Ninety patients undergoing laparoscopic nephrectomy were randomized into three groups: the control (sufentanil 0.02 μg/kg/h, Group C), sufentanil plus low dose of dexmedetomidine (0.02 μg/kg/h each, Group D1), and sufentanil plus high dose of dexmedetomidine (0.04 μg/kg/h, Group D2). The patient-controlled analgesia was programmed to deliver a bolus dose of 0.5 ml, followed by an infusion of 2 ml/h and a lockout time of 10 min. The primary goal was to calculate the cumulative amount of self-administered sufentanil; the secondary goals were to estimate pain intensity using the numerical rating scale (NRS), level of sedation, the first bowel movement, concerning adverse effects as well as duration of postoperative hospital stay.

Results

The total consumption of sufentanil in group D1 and D2 were significantly lower than in group C during the first 8 h after surgery (P < 0.05), whereas there were no statistically significant differences (P > 0.05) between group D1 and D2. Compared with group C, the NRS scores at rest during first 8 h after surgery were significantly lower in group D1 (P < 0.05). The NRS scores, neither at rest nor with movement, show statistically significant differences between group D1 and D2 at each time point following surgery (P > 0.05). The time to first flatus was shorter in group D1 compared with the control group (P < 0.05). In addition, compared with group C, group D1 and D2 had a shorter time for first defecation (P < 0.05).

Conclusions

Dexmedetomidine combined with sufentanil showed better postoperative analgesia without adverse effects, as well as facilitated bowel movements for patients undergoing laparoscopic nephrectomy.

Trial registration

We registered this study in a Chinese Clinical Trial Registry (ChiCTR) centre on Dec 23 2015 and received the registration number: ChiCTR-IPR-15007628.

New developments in the treatment of opioid-induced gastrointestinal symptoms

Chronic pain affects a large part of the global population, leading to an increase of opioid use. Opioid-induced constipation (OIC), a highly prevalent adverse effect of opioid use, has a major impact on patients' quality of life. Thanks to the introduction of new drugs for chronic constipation, which can also be used in OIC, and the development of peripherally acting mu-opioid receptor blockers, specifically for use in OIC, therapeutic options have seen major development. This review summarises current and emerging treatment options for OIC based on an extensive bibliographical search. Efficacy data for laxatives, lubiprostone, prucalopride, linaclotide, oxycodone/naloxone combinations, methylnaltrexone, alvimopan, naloxegol, naldemedine, axelopran, and bevenopran in OIC are summarised.

Laxative co-medication and changes in defecation patterns during opioid use

Introduction

Opioid-induced constipation is a clinically relevant side effect and a cause of potentially avoidable drug-related hospital admissions.

Objectives

To describe the presence of laxative co-medication, the reasons for not starting laxatives and to evaluate changes in stool patterns of opioid initiators.

Methods

In this observational study community pharmacists evaluated the availability of laxative co-medication in starting opioid users and registered reasons for non-use. Two opioid initiators per pharmacy were invited to complete questionnaires (‘Bristol stool form scale’ and ‘Rome III Diagnostic Questionnaire for the Adult Functional Gastrointestinal Disorders’) on their defecation prior to and during opioid use. Descriptive statistics and Chi square tests were used to analyse reasons for non-use of laxatives and changes in defecation patterns.

Results

Eighty-one pharmacists collected data from 460 opioid initiators. Of those, 344 (74.8%) used laxatives concomitantly. Main reason not to use laxatives was that either prescribers or patients did not consider them necessary. Sixty-seven (89.3%) of the 75 opioid starters with two questionnaires completed were not constipated at opioid start. Eleven of them (16%) developed constipation during opioid use (Chi square p=0.003). At follow-up within laxative users 10.6% were constipated compared to 20.7% in subjects without laxatives.

Conclusion

One in four opioid starters did not dispose of laxative co-medication, mainly because they were not considered necessary by either the prescriber or the patient. The prevalence of constipation doubled during opioid use. A watchful waiting strategy for the use of laxative co-medication might include a monitoring of defecation patterns with validated questionnaires.

Opioid receptors in the GI tract: targets for treatment of both diarrhea and constipation in functional bowel disorders?

Opioids have been used for centuries, mostly as a sedative and to treat pain. Currently, they are used on a global scale for the treatment of acute and chronic pain in diseases as osteoarthritis, fibromyalgia, and low back pain. Binding of opioids on opioid receptors can cause a range of different effects such as changes in stress response, analgesia, motor activity and autonomic functions. This review provide a synthetic summary of the most recent literature on the use of drugs acting on mu-receptors to treat two prevalent functional bowel disorders, presenting with opposite bowel habit. Eluxadoline and naloxegol, methylnaltrexone and naldemedine are recently FDA and/or EMA approved drugs demonstrated to be effective and safe for treatment respectively of irritable bowel syndrome subtype diarrhea and opioid induced constipation.

Naloxegol to Treat Constipation in a Patient Taking Opioids for Cancer Pain: A Case Report

Opioid-induced constipation (OIC) is a common gastrointestinal adverse effect of opioids, which can severely affect compliance and adherence to pain medication regimens and quality of life. Naloxegol has demonstrated efficacy against OIC in several studies involving patients with nonmalignant chronic pain. Here we report efficacy and tolerability of naloxegol in a 68-year-old patient with metastatic lung cancer and severe pain, treated with opioids, who presented with OIC resistant to traditional measures. Addition of naloxegol produced rapid improvement in his OIC symptoms and no apparent adverse effects while taking extended-release morphine 130 mg orally every 12 hours.

Potential of Endocannabinoids to Control Bladder Pain

Bladder-related pain is one of the most common forms of visceral pain, and visceral pain is among the most common complaints for which patients seek physician consultation. Despite extensive studies of visceral innervation and treatment of visceral pain, opioids remain a mainstay for management of bladder pain. Side effects associated with opioid therapy can profoundly diminish quality of life, and improved options for treatment of bladder pain remain a high priority. Endocannabinoids, primarily anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are endogenously-produced fatty acid ethanolamides with that induce analgesia. Animal experiments have demonstrated that inhibition of enzymes that degrade AEA or 2-AG have the potential to prevent development of visceral and somatic pain. Although experimental results in animal models have been promising, clinical application of this approach has proven difficult. In addition to fatty acid amide hydrolase (FAAH; degrades AEA) and monacylglycerol lipase (MAGL; degrades 2-AG), cyclooxygenase (COX) acts to metabolize endocannabinoids. Another potential limitation of this strategy is that AEA activates pro-nociceptive transient receptor potential vanilloid 1 (TRPV1) channels. Dual inhibitors of FAAH and TRPV1 or FAAH and COX have been synthesized and are currently undergoing preclinical testing for efficacy in providing analgesia. Local inhibition of FAAH or MAGL within the bladder may be viable options to reduce pain associated with cystitis with fewer systemic side effects, but this has not been explored. Further investigation is required before manipulation of the endocannabinoid system can be proven as an efficacious alternative for management of bladder pain.

Antinociceptive potency of a fluorinated cyclopeptide Dmt-c[D-Lys-Phe-p-CF3-Phe-Asp]NH2

Opioid peptides and opiate drugs such as morphine, mediate their analgesic effects, but also undesired side effects, mostly through activation of the mu opioid receptor. However, delta- and kappa-opioid receptors can also contribute to the analgesic effects of opioids. Recent findings showed that simultaneous activation of multiple opioid receptors may result in additional analgesia with fewer side effects. Here, we evaluated the pharmacological profile of our formerly developed mixed mu/kappa-opioid receptor ligands, Dmt-c[D-Lys-Phe-Phe-Asp]NH₂ (C-36) and Dmt-c[D-Lys-Phe-p-CF₃-Phe-Asp]NH₂ (F-81). The ability of these peptides to cross the blood–brain barrier was tested in the parallel artificial membrane permeability (PAMPA) assay. On the basis of the hot-plate test in mice after central and peripheral administration, analog F-81 was selected for the anti-nociceptive and anti-inflammatory activity assessment after peripheral administration.

The impact of naloxegol on anal sphincter function - Using a human experimental model of opioid-induced bowel dysfunction

BACKGROUND AND AIMS

Opioid treatment interferes with anal sphincter function and its regulation during defecation. This may result in straining, incomplete evacuation, and contribute to opioid-induced bowel dysfunction (OIBD). Employing an experimental model of oxycodone-induced OIBD, we hypothesized that co-administration of the peripherally acting μ-opioid antagonist naloxegol would improve anal sphincter function in comparison to placebo.

METHODS

In a double-blind randomized crossover trial, 24 healthy males were assigned to a six-day treatment of oral oxycodone 15 mg twice daily in combination with either oral naloxegol 25 mg once daily or placebo. At baseline and at day 6, anal resting pressure and the recto-anal inhibitory reflex (RAIR) were evaluated using manometry and rectal balloon distension. Furthermore, the functional lumen imaging probe was used to measure distensibility of the anal canal. Gastrointestinal symptoms were assessed with the Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire and the Bristol Stool Form Scale.

RESULTS

During oxycodone treatment, naloxegol improved RAIR-induced sphincter relaxation by 15% (-45.9 vs -38.8 mm Hg; P < 0.01). No differences in anal resting pressure and anal canal distensibility were found between treatments (all P > 0.5). Naloxegol improved PAC-SYM symptoms (mean score over days; 2.6 vs 4.5, P < 0.001) and improved stool consistency scores (mean score over days; 3.3 vs 2.9, P < 0.01).

CONCLUSIONS

In this experimental model of OIBD, naloxegol improved the RAIR and reduced gastrointestinal symptoms. Hence, in contrast to conventional laxatives, naloxegol may regulate opioid-induced anal sphincter dysfunction and facilitate the defecation process.

Colorectal Transit and Volume During Treatment With Prolonged-release Oxycodone/Naloxone Versus Oxycodone Plus Macrogol 3350

BACKGROUND/AIMS

Opioid-induced constipation (OIC) is the most common gastrointestinal (GI) side effect to opioid treatment. Opioid receptor antagonists against OIC have been introduced, but their efficacy has not been directly compared to conventional laxatives. Our aim was to compare symptoms and objective parameters of gut function in an experimental model of OIC during treatment with the opioid antagonist naloxone and oxycodone in prolonged-release (PR) formulation versus oxycodone plus macrogol 3350.

METHODS

In this randomized, double-blind, crossover trial 20 healthy men received a 5-day treatment of combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350. Regional GI transit times and segmental colorectal transit were assessed with the Motilis 3D-Transit electromagnetic capsule system. Colorectal volumes were determined by MRI. OIC symptoms were assessed with validated questionnaires, along with stool frequency and consistency.

RESULTS

Total colorectal volume did not change after 5 days' treatment with PR oxycodone/naloxone (941 vs 1036 mL; P = 0.091), but increased significantly after PR oxycodone plus macrogol treatment (912 vs 1123 mL; P < 0.001). Neither regional GI transit times nor segmental colorectal transit differed between the treatments (all P > 0.05). The Patient Assessment of Constipation Symptom Questionnaire abdominal symptoms score was lower during PR oxycodone/naloxone compared to PR oxycodone plus macrogol (0.2 vs 3.2; P = 0.002). Stool frequency was lower during PR oxycodone/naloxone compared to PR oxycodone plus macrogol (4.2 vs 5.4; P = 0.035).

CONCLUSIONS

PR oxycodone plus macrogol increases colorectal volume, but does not improve GI transit compared to PR oxycodone/naloxone. However, PR oxycodone/naloxone results in a lower abdominal symptom burden, despite higher stool frequency during macrogol treatment.

European Pain Federation position paper on appropriate opioid use in chronic pain management

Poorly controlled pain is a global public health issue. The personal, familial and societal costs are immeasurable. Only a minority of European patients have access to a comprehensive specialist pain clinic. More commonly the responsibility for chronic pain management and initiating opioid therapy rests with the primary care physician and other non‐specialist opioid prescribers. There is much confusing and conflicting information available to non‐specialist prescribers regarding opioid therapy and a great deal of unjustified fear is generated. Opioid therapy should only be initiated by competent clinicians as part of a multi‐faceted treatment programme in circumstances where more simple measures have failed. Throughout, all patients must be kept under close clinical surveillance. As with any other medical therapy, if the treatment fails to yield the desired results and/or the patient is additionally burdened by an unacceptable level of adverse effects, the overall management strategy must be reviewed and revised. No responsible clinician will wish to pursue a failed treatment strategy or persist with an ineffective and burdensome treatment. In a considered attempt to empower and inform non‐specialist opioid prescribers, EFIC convened a European group of experts, drawn from a diverse range of basic science and relevant clinical disciplines, to prepare a position paper on appropriate opioid use in chronic pain. The expert panel reviewed the available literature and harnessed the experience of many years of clinical practice to produce these series of recommendations. Its success will be judged on the extent to which it contributes to an improved pain management experience for chronic pain patients across Europe.

Significance

This position paper provides expert recommendations for primary care physicians and other non‐ specialist healthcare professionals in Europe, particularly those who do not have ready access to specialists in pain medicine, on the safe and appropriate use of opioid medications as part of a multi‐faceted approach to pain management, in properly selected and supervised patients.

Prolonged release oxycodone and naloxone treatment counteracts opioid-induced constipation in patients with severe pain compared to previous analgesic treatment

OBJECTIVE

Treatment with prolonged-release oxycodone/naloxone (PR OXN) has been shown to improve opioid induced constipation (OIC) in constipated patients. This publication reports on a real-life observational study investigating the efficacy of PR OXN with regard to bowel function in patients switching to PR OXN from WHO step 1, step 2 and step 3 opioids.

METHODS

Patients with chronic pain experiencing insufficient pain relief and/or unacceptable side effects were switched to PR OXN and monitored in this observational study with respect to efficacy regarding bowel function and efficacy regarding pain relief in comparison with previous analgesic therapy. A patient was considered a responder with respect to efficacy if this assessment was "slightly better", "better" or "much better" compared with previous therapy. Bowel function index, pain intensity, quality of life, laxative medication use, and safety analgesic were also evaluated.

RESULTS

A total of 1338 patients (mean [SD] age 64.3 [14.9], 63% female) were observed for 43 [3-166] days (median [range]) during treatment with PR OXN. Overall response rate regarding bowel function efficacy was 82.5%. Patients with symptoms of constipation at study entry obtained a clinically relevant improvement of the bowel function index (BFI) within the first 2 weeks of PR OXN treatment. Non-constipated patients at study entry maintained normal bowel function despite switching to treatment with the opioid PR OXN.

CONCLUSION

In conclusion, treatment with PR OXN results in a significant and clinically relevant improvement of bowel function. During the observation of the treatment with PR OXN patients reported an improvement of quality of life (QoL). More interestingly, non-constipated patients maintained a normal bowel function, showing prevention of constipation despite the use of an opioid.

Treatment with Naloxegol Versus Placebo: Pain Assessment in Patients with Noncancer Pain and Opioid-Induced Constipation

OBJECTIVE

To summarize results from pain and opioid use assessments with naloxegol in adults with opioid-induced constipation (OIC) and chronic noncancer pain.

METHODS

Two phase 3 randomized, double-blind, 12-week studies evaluated the efficacy and safety of oral naloxegol (12.5 or 25 mg daily) in adults (18 to < 85 years) with confirmed OIC and chronic noncancer pain: KODIAC-04 (NCT01309841) and KODIAC-05 (NCT01323790). Pain level was assessed daily (11-point numeric rating scale [NRS]; 0 = no pain, 10 = worst imaginable pain). Changes from baseline in mean weekly pain scores and opioid dose (weeks 1 through 12) were analyzed using mixed-model repeated measures.

RESULTS

At baseline, mean daily NRS average pain scores ranged from 4.5 to 4.8 for all groups in KODIAC-04 (N = 652) and were 4.6 for each group in KODIAC-05 (N = 700). Respective mean ± SD changes from baseline average pain for placebo, naloxegol 12.5 mg, and naloxegol 25 mg were -0.2 ± 1.07, -0.3 ± 1.05 (P = 0.773 vs. placebo), and 0.2 ± 0.95 (P = 0.837 vs. placebo; KODIAC-04) and -0.1 ± 0.94, -0.1 ± 0.87 (P = 0.744), and 0.0 ± 1.18 (P = 0.572; KODIAC-05). At baseline, mean daily opioid doses ranged from 135.6 to 143.2 morphine equivalent units (MEUs)/day in KODIAC-04, and from 119.9 to 151.7 MEUs/day in KODIAC-05. Respective mean ± SD changes from baseline dose were -1.8 ± 30.19, -2.3 ± 20.52 (P = 0.724 vs. placebo), and 0.4 ± 13.01 (P = 0.188 vs. placebo; KODIAC-04) and -0.3 ± 17.14, -1.3 ± 17.11 (P = 0.669 vs. placebo), and 0.1 ± 8.54 (P = 0.863 vs. placebo; KODIAC-05). Changes in maintenance opioid dose were few; reasons for such changes were similar across treatment groups.

CONCLUSION

Centrally mediated opioid analgesia was maintained during treatment with naloxegol in patients with noncancer pain and OIC.

Prolonged-Release Oxycodone/Naloxone Improves Anal Sphincter Relaxation Compared to Oxycodone Plus Macrogol 3350

BACKGROUND

Opioid analgesics inhibit anal sphincter function and contribute to opioid-induced bowel dysfunction (OIBD). However, it is unknown whether the inhibition can be reduced by opioid antagonism with prolonged-release (PR) naloxone and how this compares to laxative treatment.

AIMS

To compare the effects of combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350 on anal sphincter function and gastrointestinal symptoms.

METHODS

A randomized, double-blind, crossover trial was conducted in 20 healthy men. Participants were treated for 5 days with combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350. Resting anal pressure, anal canal distensibility, and relaxation of the internal sphincter to rectal distension were evaluated before treatment (baseline) and on day 5. The Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire, stool frequency, and stool consistency were assessed daily.

RESULTS

Both PR oxycodone/naloxone and PR oxycodone plus macrogol treatment decreased sphincter relaxation compared to baseline (- 27.5%; P < 0.001 and - 14.7%; P = 0.01). However, sphincter relaxation was increased after PR naloxone/oxycodone treatment compared to macrogol (difference = + 17.6%; P < 0.001). Resting anal pressure and anal canal distensibility did not differ between treatments. PAC-SYM abdominal symptoms score was lower during PR naloxone compared to macrogol (0.2 vs. 3.2; P = 0.002). The number of bowel movements was lower during PR naloxone versus macrogol (4.2 vs. 5.4; P = 0.035).

CONCLUSION

Relaxation of the internal anal sphincter was significantly better after PR oxycodone/naloxone treatment compared to PR oxycodone plus macrogol 3350. These findings highlight that OIBD may require specific therapy against the complex, pan-intestinal effects of opioids.

Opioid-Induced Constipation and Bowel Dysfunction: A Clinical Guideline

OBJECTIVE

To formulate timely evidence-based guidelines for the management of opioid-induced bowel dysfunction.

SETTING

Constipation is a major untoward effect of opioids. Increasing prescription of opioids has correlated to increased incidence of opioid-induced constipation. However, the inhibitory effects of opioids are not confined to the colon, but also affect higher segments of the gastrointestinal tract, leading to the coining of the term "opioid-induced bowel dysfunction."

METHODS

A literature search was conducted using Medline, EMBASE, and EMBASE Classic, and the Cochrane Central Register of Controlled Trials. Predefined search terms and inclusion/exclusion criteria were used to identify and categorize relevant papers. A series of statements were formulated and justified by a comment, then labeled with the degree of agreement and their level of evidence as judged by the Strength of Recommendation Taxonomy (SORT) system.

RESULTS

From a list of 10,832 potentially relevant studies, 33 citations were identified for review. Screening the reference lists of the pertinent papers identified additional publications. Current definitions, prevalence, and mechanism of opioid-induced bowel dysfunction were reviewed, and a treatment algorithm and statements regarding patient management were developed to provide guidance on clinical best practice in the management of patients with opioid-induced constipation and opioid-induced bowel dysfunction.

CONCLUSIONS

In recent years, more insight has been gained in the pathophysiology of this "entity"; new treatment approaches have been developed, but guidelines on clinical best practice are still lacking. Current knowledge is insufficient regarding management of the opioid side effects on the upper gastrointestinal tract, but recommendations can be derived from what we know at present.

Ultrasound-guided Stellate Ganglion Block Improves Gastrointestinal Function After Thoracolumbar Spinal Surgery

PURPOSE

The purpose of this study was to investigate the effects of stellate ganglion block (SGB) on gastrointestinal function after thoracolumbar spinal surgery.

METHODS

Forty patients with thoracolumbar fracture scheduled for posterior spinal surgery were randomly assigned to 2 groups: ultrasound-guided SGB or sham (control group). After induction, ultrasound-guided SGB (n = 20) or a sham procedure (n = 20) was conducted with a 6-mL injection of 1% lidocaine or 0.9% saline, respectively. Primary outcomes were postoperative gastrointestinal function, including auscultation of bowel sounds, incidence and degree of abdominal bloating, flatus time, and paralytic ileus.

FINDINGS

Patients in the SGB group had better gastrointestinal function compared with those in the sham (control) group, as indicated by more regular bowel sounds at 24 and 36 hours postoperatively (80% vs 40%, P = 0.024, and 95% vs 60%, P = 0.023), lesser abdominal bloating (10% vs 45%, P = 0.034), and slightly shorter flatus time (mean [SD], 12.0 [4.4] vs 14.7 [4.6] hours, P = 0.068). Survival analysis based on regular bowel sounds found a significant difference between the 2 groups (P = 0.004). In addition, more patients had higher satisfaction after SGB (85% vs 45%, P = 0.020). No postoperative ileus or mortality occurred.

IMPLICATIONS

In this preliminary study, ultrasound-guided SGB accelerated the return of gastrointestinal transit, alleviated bowel symptoms, and improved patient satisfaction after thoracolumbar spinal surgery. chictr.org.cn identifier: ChiCTR-TRC-14004289.

Opioid-Induced Bowel Dysfunction in Patients Undergoing Spine Surgery: Comparison of Oxycodone and Oxycodone-Naloxone Treatment

Introduction

Opioids are needed for postoperative pain in spine surgery patients, but opioid-induced constipation is a harmful adverse event. The aim of this clinical trial was to compare the use of a controlled-release oxycodone-naloxone combination product with oxycodone controlled-release tablets in these patients. The main outcome measure was the prevalence of constipation at 7 days postoperatively assessed with a Bowel Function Index questionnaire. A follow-up assessment at 21 days after surgery was also included.

Methods

A total of 180 patients undergoing spine surgery, 91 having preoperative opioids in use and 89 opioid-naïve, were randomized to receive twice-daily oxycodone 10 mg or oxycodone-naloxone 10/5 mg controlled-release tablets for the first 7 postoperative days. Patients were followed-up for 21 days after surgery.

Results

At baseline, prevalence of constipation was common both in the opioid-naïve—25/87 (29%) and on-opioid groups 43/90 (48%) (P = 0.009). This increased at 7 days postoperatively with no difference between the groups, 54/89 with oxycodone and 54/88 with oxycodone-naloxone had constipation. At 21 days, constipation was less than in the baseline in both groups, in the opioid-naïve group the prevalence of constipation was 3/43 (7%) in patients with oxycodone-naloxone compared to 9/44 (21%) with oxycodone (effect size 0.68; P = 0.068). Both study compounds provided similar pain relief and were well tolerated.

Conclusion

In patients presented for back surgery, the prevalence of constipation was significantly higher than that in the community. In opioid-naïve subjects, oxycodone-naloxone was beneficial concerning constipation; but this was not distinguishable in subjects with chronic opioid use. The analgesic efficacy of oxycodone and oxycodone-naloxone was similar.

Trial registration: European Clinical Trials Database (EudraCT no. 2012-001816-42) and ClinicalTrials.gov database (Identifier: NCT02573922).

Short-term oxycodone treatment does not affect electrogenic ion transport in isolated mucosa from the human rectosigmoid colon

OBJECTIVE

Opioid therapy is associated with altered secretion and motility of the gut. The relative contribution of decreased secretion to the development of opioid-induced constipation remains unknown.

MATERIALS AND METHODS

Twenty-five healthy males were treated with oxycodone for 5 d in a placebo-controlled, randomised cross-over design. Gastrointestinal adverse effects were assessed with validated questionnaires (bowel function index and gastrointestinal symptom rating scale). Rectosigmoid mucosal biopsies were taken at baseline and on day 5 during both treatments and mounted in Ussing chambers. Electrogenic ion transport parameters (short circuit current (SCC) and slope conductance) were measured after addition of secretagogues (prostaglandin E2 (PGE2) (6 μm), theophylline (400 μm)), and an inhibitor (ouabain (200 μm)). Additionally, morphine (50 μm) was added to investigate the direct opioid effect on colonic mucosa.

RESULTS

Questionnaires showed pronounced bowel symptoms, including constipation during oxycodone treatment (eight-fold increase in bowel function index score from day 1 to day 5 (p < 0.001) while no significant change occurred during placebo treatment (p = 0.47). Basal SCC and slope conductance did not differ between treatments (all p > 0.05) and application with PGE2, theophylline, and ouabain yielded comparable results on all examinations (all p > 0.05). Morphine application consistently did not evoke a change in ion transport.

CONCLUSION

Compared to placebo, epithelial electrogenic ion transport is not altered in mucosal biopsies from the rectosigmoid colon following 5-d oxycodone treatment. The secretory mechanisms in isolated mucosa appear to play a negligible role in the development of opioid-induced constipation.

Factors Associated With the Prophylactic Prescription of a Bowel Regimen to Prevent Opioid-Induced Constipation

OBJECTIVE

Identify factors associated with the prophylactic prescription of a bowel regimen with an inpatient opioid prescription.

METHODS

This was a retrospective cohort study from June 1, 2013, to October 31, 2014 of pediatric inpatients prescribed an oral or intravenous opioid on the general medical/surgical floors. We identified patients with or without a prophylactic prescription of a bowel regimen. We obtained patient demographics, prescriber training level and service and used multivariate logistic regression to analyze the factors associated with prophylactic bowel regimen and opioid prescription.

RESULTS

Of the 6682 encounters that met study criteria, only 966 (14.5%) encounters had prophylactic prescriptions. Patient factors associated with prophylactic prescription include increasing age (per year; odds ratio [OR] = 1.06, 95% confidence interval [CI] 1.05-1.07) and sickle cell diagnosis (OR = 3.19, 95% CI 2.08-4.91). Medication factors associated with prophylactic prescription include a scheduled opioid prescription (OR = 1.75, 95% CI 1.46-2.1) and a prescription for oxycodone (OR = 3.59, 95% CI 2.57-5.00) or morphine (OR = 1.84, 95% CI 1.39-2.44), compared with acetaminophen-hydrocodone. Compared with medical providers, surgeons were less likely (OR = 0.43, 95% CI 0.35-0.53) and pain service providers were more likely to prescribe a prophylactic bowel regimen (OR = 4.12, 95% CI 3.13-5.43).

CONCLUSIONS

More than 85% of inpatient opioid prescriptions did not receive a prophylactic bowel regimen. Future research should examine factors (eg, clinical decision support tools) to increase prophylactic prescription of bowel regimens with opioids for populations found to have lower rates.

The role of naloxegol in the management of opioid-induced bowel dysfunction

Opioid-induced constipation (OIC) and other gastrointestinal (GI) symptoms of opioid-induced bowel dysfunction (OIBD) significantly deteriorate patients' quality of life and may lead to noncompliance with opioid schedule and undertreatment of pain. Although traditional oral laxatives are the first-line treatment of OIC, they do not address OIBD pathophysiology, and display numerous adverse effects. OIC treatment includes prokinetics (lubiprostone), opioid switch, and changing route of opioid administration. Targeted management of OIBD comprises the use of purely peripherally acting μ-opioid receptor antagonists (PAMORA): naloxegol and methylnaltrexone. Naloxegol (NKTR-118) is a polymer conjugate of the opioid antagonist naloxone. The polyethylene glycol limits naloxegol capacity to cross the blood-brain barrier (BBB). Naloxegol is substrate for the P-glycoprotein (P-gp) transporter. The central nervous system penetration of naloxegol is negligible due to reduced permeability and its increased efflux across the BBB, related to P-gp transporter. Naloxegol antagonizes μ- and κ-opioid receptors and displays low affinity to δ-opioid receptors in the GI tract, thereby decreasing OIBD symptoms without reversing central analgesic effects. Naloxegol is metabolised through CYP3A4 to six metabolites, with the majority of the dose (68%) excreted with faeces and less (16%) with urine. The dose of naloxegol equals 25 mg administered orally once daily on a fasting condition. Mild or moderate hepatic impairment has no impact on naloxegol dosing; naloxegol was not studied and is not recommended in patients with hepatic failure. Dose reduction (12.5 mg once daily) and caution is recommended in patients with moderate-to-severe renal impairment. Efficacy (bowel movement in 42-49% of patients not responsive to laxatives) and safety of naloxegol were confirmed in studies conducted in patients with OIC and nonmalignant pain. Naloxegol may be useful for cancer patients with OIC, although studies in this population are lacking.

6β-N-Heterocyclic Substituted Naltrexamine Derivative BNAP: A Peripherally Selective Mixed MOR/KOR Ligand

The 6β-N-heterocyclic naltrexamine derivative, NAP, has been demonstrated to be a peripherally selective mu opioid receptor modulator. To further improve peripheral selectivity of this highly potent ligand, its pyridal ring was quaterinized with benzyl bromide to produce BNAP. In radioligand binding assay, the Ki of BNAP for MOR was 0.76 ± 0.09 nM and was >900-fold more selective for MOR than DOR. The Ki for KOR was 3.46 ± 0.05 nM. In [(35)S]GTPγS ligand stimulated assay, BNAP showed low agonist efficacy with 14.6% of the maximum response of DAMGO with an EC50 of 4.84 ± 0.6 nM. However, unlike its parent compound NAP, BNAP displayed partial agonist activity at KOR with % maximum response at 45.9 ± 1.7% of U50,488H. BNAP did not reverse morphine-induced antinociception when administered subcutaneously but did antagonize when administered intracerebroventricularly. BNAP antagonized morphine-induced contractions of the circular muscle in mice colon. BNAP inhibition of field-stimulated contractions in longitudinal muscle strips for the guinea-pig ileum were also blocked by nor-BNI, a kappa opioid receptor antagonist. BNAP induced inhibition of acetic acid induced abdominal stretching in chronic morphine treated mice. These findings suggest that BNAP is a dual MOR antagonist/KOR agonist and may have functional use in irritable bowel patients.

Impact of Treatment with Naloxegol for Opioid-Induced Constipation on Patients' Health State Utility

Introduction

Opioid-induced constipation (OIC) is the most common side effect of opioid treatment. Treatment for OIC typically involves a laxative. However, some patients have an inadequate response to these (laxative inadequate responders, or LIR). This has led to the development of treatments such as naloxegol. This analysis estimates the impact of naloxegol on the health state utility of LIR patients, examines if this utility impact is driven by the change in OIC status, and estimates the utility impact of relief of OIC.

Methods

The analysis was conducted using data from two 12-week randomized controlled trials, KODIAC 4 (ClinicalTrials.gov identifier, NCT01309841) and KODIAC 5 (ClinicalTrials.gov identifier, NCT01323790), plus KODIAC 7 (ClinicalTrials.gov identifier, NCT01395524), a 12-week extension to KODIAC 4. All were designed to assess the efficacy and safety of oral naloxegol (12.5 and 25 mg) compared to placebo. Health state utility data were collected through the EuroQol—five dimensions questionnaire (EQ-5D-3L). Descriptive analysis was undertaken to estimate how EQ-5D utility scores and EQ-5D domain responses varied with treatment, OIC status, and over time. A repeated measure mixed-effects model was used to predict the change from baseline in health state utility score over time.

Results

Compared with placebo, LIR patients treated with naloxegol 25 mg reported a 0.08 improvement in the EQ-5D overall score after 12 weeks of treatment. The analyses also suggest that change in OIC status is a key driver of the impact of OIC treatment on health state utility. When other factors are controlled, relieving OIC is associated with a 0.05 improvement in health state utility, although treatment with naloxegol is associated with an improvement in health state utility over and above the improvement in OIC status.

Conclusion

These analyses suggest that treatment with naloxegol improves patients’ health state utility; driven predominantly by the relief of patients’ constipation.

Funding

AstraZeneca.

Constipation in Elderly Patients with Noncancer Pain: Focus on Opioid-Induced Constipation

Constipation is a common and often debilitating condition in the elderly, which may be caused by underlying disease conditions, structural abnormalities in the bowel, and a variety of medications such as anticholinergics, antidepressants, and opiates. In this review, we focus on opioid-induced constipation (OIC), which is often underrecognized and undertreated in the elderly. When opioid therapy is initiated, healthcare providers are encouraged to evaluate risk factors for the development of constipation as part of a thorough patient history. To this end, the patient assessment should include the use of validated instruments, such as the Bristol Stool Scale and Bowel Function Index, to confirm the diagnosis and provide a basis for evaluating treatment outcomes. Healthcare providers should use a stepwise approach to the treatment of OIC in the elderly. Conventional laxatives are a first-line option and considered well tolerated with short-term use as needed; however, evidence is lacking to support their effectiveness in OIC. Moreover, because of the risk of adverse events and other considerations, such as chewing difficulties and swallowing disorders, conventional oral laxatives may be inappropriate for the treatment of OIC in the elderly. Thus, the availability of new pharmacologic agents such as the peripherally acting µ-opioid receptor antagonists methylnaltrexone and naloxegol, which target the underlying causes of OIC, and the secretagogue lubiprostone may provide more effective treatment options for elderly patients with OIC.

How Do Hospital Palliative Care Teams Use the WHO Guidelines to Manage Unrelieved Cancer Pain? A 1-Year, Multicenter Audit in Japan

It has been reported that pain relief for patients with cancer is suboptimal in Japan. This has been mainly attributed to inadequate dissemination of the World Health Organization (WHO) guidelines for cancer pain management. To better understand this problem, we reviewed how 6 hospital palliative care teams (HPCTs) used the WHO guidelines for unrelieved pain in a 1-year audit that included 534 patients. The HPCT interventions were classified according to the contents of the WHO guidelines. In our study, HPCT interventions involved opioid prescriptions in >80% of referred patients, and “For the Individual” and “Attention to Detail” were the 2 most important principles. Our study indicates which parts of the WHO guidelines should be most heavily emphasized, when disseminating them in Japan.

Opioid treatment and hypoalbuminemia are associated with increased hospitalisation rates in chronic pancreatitis outpatients

BACKGROUND/OBJECTIVES

Chronic pancreatitis (CP) is a complex and debilitating disease with high resource utilisation. Prospective data on hospital admission rates and associated risk factors are scarce. We investigated hospitalisation rates, causes of hospitalisations and associated risk factors in CP outpatients.

METHODS

This was a prospective cohort study comprising 170 patients with CP. The primary outcome was time to first pancreatitis related hospitalisation and secondary outcomes were the annual hospitalisation frequency (hospitalisation burden) and causes of hospitalisations. A number of clinical and demographic parameters, including pain pattern and severity, opioid use and parameters related to the nutritional state, were analysed for their association with hospitalisation rates.

RESULTS

Of the 170 patients, 57 (33.5%) were hospitalised during the follow-up period (median 11.4 months [IQR 3.8-26.4]). The cumulative hospitalisation incidence was 7.6% (95% CI; 4.5-12.2) after 30 days and 28.8% (95% CI; 22.2-35.7) after 1 year. Eighteen of the hospitalised patients (32%) had three or more admissions per year. High dose opioid treatment (>100 mg per day) (Hazard Ratio 3.1 [95% CI; 1.1-8.5]; P = 0.03) and hypoalbuminemia (<36 g/l) (Hazard Ratio 3.8 [95% CI; 2.0-7.8]; P < 0.001) were identified as independent risk factors for hospitalisation. The most frequent causes of hospitalisations were pain exacerbation (40%) and common bile duct stenosis (28%).

CONCLUSIONS

One-third of CP outpatients account for the majority of hospital admissions and associated risk factors are high dose opioid treatment and hypoalbuminemia. This information should be implemented in outpatient monitoring strategies to identify risk patients and improve treatment.

Management of chronic visceral pain

Despite marked differences in underlying pathophysiology, the current management of visceral pain largely follows the guidelines derived from the somatic pain literature. The effective management of patients with chronic visceral pain should be multifaceted, including both pharmacological and psychological interventions, thereby providing a mechanism-orientated approach to treatment. Patients can frequently become disenfranchised, and subsequently disengaged, with healthcare providers leading to repeated consultations. Thus, a key aspect of management is to break this cycle by validating patients' symptoms, adopting an empathic approach and taking time to educate patients. To optimize treatment and outcomes in chronic visceral pain we need to move away from approaches exclusively based on dealing with peripheral nociceptive input toward more holistic strategies, taking into account alterations in central pain processing.

Opioid-induced bowel dysfunction in healthy volunteers assessed with questionnaires and MRI

OBJECTIVE

Opioid treatment is associated with numerous gastrointestinal adverse effects collectively known as opioid-induced bowel dysfunction (OIBD). Most current knowledge of the pathophysiology derives from animal studies limited by species differences and clinical studies, which have substantial confounders that make evaluation difficult. An experimental model of OIBD in healthy volunteers in a controlled setting is therefore highly warranted. The aim of this study was to assess bowel function in healthy volunteers during opioid treatment using subjective and objective methods.

METHODS

Twenty-five healthy men were assigned randomly to oxycodone or placebo for 5 days in a cross-over design. The analgesic effect was assessed with muscle pressure algometry and adverse effects were measured using questionnaires including the bowel function index, gastrointestinal symptom rating scale, patient assessment of constipation symptoms and the Bristol stool form scale. Colorectal volumes were determined using a newly developed MRI method.

RESULTS

Compared with baseline, oxycodone increased pain detection thresholds by 8% (P=0.02). Subjective OIBD was observed as increased bowel function index (464% increase; P<0.001), gastrointestinal symptom rating scale (37% increase; P<0.001) and patient assessment of constipation symptoms (198% increase; P<0.001). Objectively, stools were harder and drier during oxycodone treatment (P<0.001) and segmental colorectal volumes increased in the caecum/ascending colon by 41% (P=0.005) and in the transverse colon by 20% (P=0.005). No associations were detected between questionnaire scores and colorectal volumes.

CONCLUSION

Experimental OIBD in healthy volunteers was induced during oxycodone treatment. This model has potential for future interventional studies to discriminate the efficacies of different laxatives, peripheral morphine antagonists and opioid treatments.

The Impact of Opioid Treatment on Regional Gastrointestinal Transit

Background/Aims

To employ an experimental model of opioid-induced bowel dysfunction in healthy human volunteers, and evaluate the impact of opioid treatment compared to placebo on gastrointestinal (GI) symptoms and motility assessed by questionnaires and regional GI transit times using the 3-dimensional (3D)-Transit system.

Methods

Twenty-five healthy males were randomly assigned to oxycodone or placebo for 5 days in a double blind, crossover design. Adverse GI effects were measured with the bowel function index, gastrointestinal symptom rating scale, patient assessment of constipation symptom questionnaire, and Bristol stool form scale. Regional GI transit times were determined using the 3D-Transit system, and segmental transit times in the colon were determined using a custom Matlab^® graphical user interface.

Results

GI symptom scores increased significantly across all applied GI questionnaires during opioid treatment. Oxycodone increased median total GI transit time from 22.2 to 43.9 hours (P < 0.001), segmental transit times in the cecum and ascending colon from 5.7 to 9.9 hours (P = 0.012), rectosigmoid colon transit from 2.7 to 9.0 hours (P = 0.044), and colorectal transit time from 18.6 to 38.6 hours (P = 0.001). No associations between questionnaire scores and segmental transit times were detected.

Conclusions

Self-assessed GI adverse effects and increased GI transit times in different segments were induced during oxycodone treatment. This detailed information about segmental changes in motility has great potential for future interventional head-to-head trials of different laxative regimes for prevention and treatment of constipation.

Definition, diagnosis and treatment strategies for opioid-induced bowel dysfunction–Recommendations of the Nordic Working Group

Background and aims

Opioid-induced bowel dysfunction (OIBD) is an increasing problem due to the common use of opioids for pain worldwide. It manifests with different symptoms, such as dry mouth, gastro-oesophageal reflux, vomiting, bloating, abdominal pain, anorexia, hard stools, constipation and incomplete evacuation. Opioid-induced constipation (OIC) is one of its many symptoms and probably the most prevalent. The current review describes the pathophysiology, clinical implications and treatment of OIBD.

Methods

The Nordic Working Group was formed to provide input for Scandinavian specialists in multiple, relevant areas. Seven main topics with associated statements were defined. The working plan provided a structured format for systematic reviews and included instructions on how to evaluate the level of evidence according to the GRADE guidelines. The quality of evidence supporting the different statements was rated as high, moderate or low. At a second meeting, the group discussed and voted on each section with recommendations (weak and strong) for the statements.

Results

The literature review supported the fact that opioid receptors are expressed throughout the gastrointestinal tract. When blocked by exogenous opioids, there are changes in motility, secretion and absorption of fluids, and sphincter function that are reflected in clinical symptoms. The group supported a recent consensus statement for OIC, which takes into account the change in bowel habits for at least one week rather than focusing on the frequency of bowel movements. Many patients with pain receive opioid therapy and concomitant constipation is associated with increased morbidity and utilization of healthcare resources. Opioid treatment for acute postoperative pain will prolong the postoperative ileus and should also be considered in this context. There are no available tools to assess OIBD, but many rating scales have been developed to assess constipation, and a few specifically address OIC. A clinical treatment strategy for OIBD/OIC was proposed and presented in a flowchart. First-line treatment of OIC is conventional laxatives, lifestyle changes, tapering the opioid dosage and alternative analgesics. Whilst opioid rotation may also improve symptoms, these remain unalleviated in a substantial proportion of patients. Should conventional treatment fail, mechanism-based treatment with opioid antagonists should be considered, and they show advantages over laxatives. It should not be overlooked that many reasons for constipation other than OIBD exist, which should be taken into consideration in the individual patient.

Conclusion and implications

It is the belief of this Nordic Working Group that increased awareness of adverse effects and OIBD, particularly OIC, will lead to better pain treatment in patients on opioid therapy. Subsequently, optimised therapy will improve quality of life and, from a socio-economic perspective, may also reduce costs associated with hospitalisation, sick leave and early retirement in these patients.

Methylnaltrexone for opioid-induced constipation: review and meta-analyses for objective plus subjective efficacy and safety outcomes

Introduction

Opioid-induced constipation (OIC) is a frequent adverse event that impairs patients’ quality of life. This article evaluates the objective plus subjective efficacy and the safety of methylnaltrexone (MNTX) in OIC patients.

Methods

Randomized controlled trials from a recent systematic review were included. In addition, a PubMed search was conducted for January 2014 to December 21, 2015. We included randomized controlled trials with adult OIC patients, MNTX as study drug, and OIC as primary outcome. Results were categorized in three outcome types: objective outcome measures (eg, time to laxation), patient-reported outcomes (eg, straining), and global burden measures (eg, constipation distress). Dichotomous meta-analyses with risk ratios (RRs) and 95% confidence intervals (CIs) were calculated using RevMan 5.3. Only comparisons between MNTX and placebo were made.

Results

We included seven studies with 1,860 patients. A meta-analysis revealed that patients under MNTX had considerably more rescue-free bowel movement within 4 hours after the first dose (RR 3.74, 95% CI 2.87 to 4.86; five studies, n=938; I²=0). Results of the review indicated that patients under MNTX had a higher stool frequency and needed less time to laxation compared with placebo. Moreover, patients receiving MNTX tended to have better values in patient-reported outcomes and global burden measures. Meta-analyses on safety revealed that patients under MNTX experienced more abdominal pain (RR 2.38, 95% CI 1.75 to 3.23; six studies, n=1,412; I²=60%) but showed a nonsignificant tendency in nausea (RR 1.27, 95% CI 0.90 to 1.78; six studies, n=1,412; I²=12%) and diarrhea (RR 1.45, 95% CI 0.94 to 2.24; five studies, n=1,258; I²=45%). The incidence of MNTX-related serious adverse events was 0.2% (4/1,860).

Conclusion

MNTX has been shown to be effective and safe. Future randomized controlled trials should consequently incorporate objective outcome measures, patient-reported outcomes, and global burden measures, and research the efficacy of MNTX in other populations, for example, patients under opioids after surgical procedures.

Is Timing of Medical Therapy Related to Outcome in Painful Chronic Pancreatitis?

OBJECTIVES

The authors investigated if timing of medical treatment is associated with the analgesic effect of pregabalin or placebo in patients with chronic pancreatitis (CP).

METHODS

Sixty-four patients received pregabalin (150-300 mg twice a day) or matching placebo for 3 consecutive weeks. Responders to treatment were defined as patients with a reduction in clinical pain scores of 30% or greater. Factors associated with timing of pain treatment (ie, duration of CP and opioid usage) were collected at baseline. In addition, other factors that potentially could influence outcome (eg, clinical pain scores prior to study medication, diabetes, and exocrine pancreatic insufficiency) were also included. Conventional groupwise logistic regression and analysis on the individual patient level with a machine learning technique were used to predict treatment response.

RESULTS

In the conventional statistical analysis duration of CP (odds ratio, 0.9; 95% confidence interval, 0.8-1.1; P = 0.3) and opioid treatment (odds ratio, 1.0; 95% confidence interval, 0.9-1.1; P = 0.6) were not associated with pain relief. In addition, none of the supplementary factors were associated with treatment response (all P > 0.1). Likewise, in the individual patient-level analysis, none of the included variables reached classification accuracies greater than chance level (all P > 0.1).

CONCLUSIONS

Pregabalin can be added as adjuvant analgesic at any time point during the disease course of CP.

Opioid-induced constipation in chronic noncancer pain

PURPOSE OF REVIEW

Opioid-based management of noncancer pain has become much more prevalent over the last 2 decades and is responsible for a wide range of side-effects, particularly affecting the intestinal tract causing opioid-induced constipation (OIC). This review will consider results of recent clinical trials that have provided evidence of new pharmacological management options for the treatment of OIC.

RECENT FINDINGS

Supportive use of conventional agents, such as stool softeners, osmotic laxatives, and stimulating laxatives in OIC has limited efficacy. The peripheral μ-opioid receptor antagonist (PAMORA) methylnaltrexone (MNTX) was first FDA approved for OIC in patients with advanced illness and later also for OIC in noncancer pain patients; clinical trial results indicated MNTX did not reverse opioid analgesia and did not trigger central opioid withdrawal. Another PAMORA, the orally available naloxegol, has also gained recent FDA approval for the treatment of OIC in adults with chronic, noncancer pain. Lubiprostone, a bicyclical fatty acid acting via activation of intestinal chloride channel-2 (ClC-2), was also approved for OIC treatment in patients with noncancer pain.

SUMMARY

PAMORA MNTX and naloxegol and the intestinal chloride channel-2 (ClC-2) activator lubiprostone represent additional possible therapeutic options for the management of OIC in patients with chronic noncancer pain.