Emerging treatments in neurogastroenterology: a multidisciplinary working group consensus statement on opioid-induced constipation

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.

Randomized Phase III and Extension Studies of Naldemedine in Patients With Opioid-Induced Constipation and Cancer

Purpose Opioid-induced constipation (OIC) is a frequent and debilitating adverse effect (AE) of opioids-common analgesics for cancer pain. We investigated the efficacy and safety of a peripherally acting μ-opioid receptor antagonist, naldemedine (S-297995), for OIC, specifically in patients with cancer. Patients and Methods This phase III trial consisted of a 2-week, randomized, double-blind, placebo-controlled study (COMPOSE-4) and an open-label, 12-week extension study (COMPOSE-5). In COMPOSE-4, eligible adults with OIC and cancer were randomly assigned on a 1:1 basis to receive once-daily oral naldemedine 0.2 mg or placebo. The primary end point was the proportion of spontaneous bowel movement (SBM) responders (≥ 3 SBMs/week and an increase of ≥ 1 SBM/week from baseline). The primary end point of COMPOSE-5 was safety. Results In COMPOSE-4, 193 eligible patients were randomly assigned to naldemedine (n = 97) or placebo (n = 96). The proportion of SBM responders in COMPOSE-4 was significantly greater with naldemedine than with placebo (71.1% [69 of 97 patients] v 34.4% [33 of 96 patients]; P < .0001). A greater change from baseline was observed with naldemedine than with placebo in the frequency of SBMs/week (5.16 v 1.54; P < .0001), SBMs with complete bowel evacuation/week (2.76 v 0.71; P < .0001), and SBMs without straining/week (3.85 v 1.17; P = .0005). In COMPOSE-4, more patients treated with naldemedine than with placebo reported treatment-emergent AEs (TEAEs) (44.3% [43 of 97 patients] v 26.0% [25 of 96 patients]; P = .01); in COMPOSE-5, 105 (80.2%) of 131 of patients reported TEAEs. Diarrhea was the most frequently reported TEAE in COMPOSE-4 (19.6% [19 of 97 patients] v 7.3% [seven of 96 patients] with naldemedine v placebo) and COMPOSE-5 (18.3% [24 of 131 patients] with naldemedine). Naldemedine was not associated with signs or symptoms of opioid withdrawal and had no notable impact on opioid-mediated analgesia. Conclusion Once-daily oral naldemedine 0.2 mg effectively treated OIC and was generally well tolerated in patients with OIC and cancer.

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.

New therapeutic perspectives in irritable bowel syndrome: Targeting low-grade inflammation, immuno-neuroendocrine axis, motility, secretion and beyond

Irritable bowel syndrome (IBS) is a chronic, recurring, and remitting functional disorder of the gastrointestinal tract characterized by abdominal pain, distention, and changes in bowel habits. Although there are several drugs for IBS, effective and approved treatments for one or more of the symptoms for various IBS subtypes are needed. Improved understanding of pathophysiological mechanisms such as the role of impaired bile acid metabolism, neurohormonal regulation, immune dysfunction, the epithelial barrier and the secretory properties of the gut has led to advancements in the treatment of IBS. With regards to therapies for restoring intestinal permeability, multiple studies with prebiotics and probiotics are ongoing, even if to date their efficacy has been limited. In parallel, much progress has been made in targeting low-grade inflammation, especially through the introduction of drugs such as mesalazine and rifaximin, even if a better knowledge of the mechanisms underlying the low-grade inflammation in IBS may allow the design of clinical trials that test the efficacy and safety of such drugs. This literature review aims to summarize the findings related to new and investigational therapeutic agents for IBS, most recently developed in preclinical as well as Phase 1 and Phase 2 clinical studies.

Phase 1, Randomized, Double-Blind, Placebo-Controlled Studies on the Safety, Tolerability, and Pharmacokinetics of Naldemedine in Healthy Volunteers

Naldemedine (S-297995) is a peripherally acting μ-opioid receptor antagonist for the treatment of opioid-induced constipation, a common side effect of opioid therapy. We determined the safety, tolerability, and pharmacokinetic profiles of oral naldemedine in healthy volunteers in 2 randomized, double-blind, placebo-controlled, phase 1 studies. In the single ascending dose study, subjects received a single dose of naldemedine (0.1-100 mg; n = 42) or placebo (n = 14). In the multiple ascending dose study, subjects received once-daily naldemedine (3-30 mg; n = 27) or placebo (n = 9) for 10 days. On day 1 of the single ascending dose studies and day 10 of the multiple ascending dose studies, respectively, the maximum plasma concentration levels of naldemedine were 1.98 to 2510 ng/mL and 73.8 to 700 ng/mL, peaked at 0.5 hours and 0.5 to 0.75 hours, and the fraction excreted in urine was 15.9% to 20.5% and 19.7% to 19.1%. There were no major safety or tolerability concerns even at naldemedine doses 150 to 500 times the therapeutic dose of 0.2 mg. The incidence of adverse events was not dose dependent. Gastrointestinal adverse events occurred more frequently with naldemedine vs placebo, and all of these were considered treatment related. Overall, naldemedine was rapidly absorbed, and no safety or tolerability issues were noted at the doses evaluated.

Effect of Intravenous Fluids and Analgesia on Dysmotility in Patients With Acute Pancreatitis: A Prospective Cohort Study

OBJECTIVES

Analgesia and intravenous fluid resuscitation are cornerstones of initial patient management in acute pancreatitis (AP). The aim was to investigate the effect of intravenous fluids and analgesia on gastrointestinal motility in the early course of AP.

METHODS

Gastrointestinal dysmotility was assessed using the Gastroparesis Cardinal Symptom Index (GCSI). One-way analysis of variance and analysis of covariance were conducted, adjusting for age, sex, body mass index, severity of AP, preexisting diabetes mellitus, and time from first symptom onset to hospital admission.

RESULTS

A total of 108 patients with AP were prospectively enrolled. Opioid analgesia, when compared with nonopioid analgesia, was significantly associated with increase in total GCSI score in both unadjusted and adjusted analyses. There was no significant difference between aggressive and nonaggressive fluid resuscitation in both unadjusted and adjusted analyses. A combination of opioids and any intravenous fluids was associated with a significantly increased total GCSI score compared with opioids and no intravenous fluids in both unadjusted and adjusted analyses. Duration of symptoms was the confounder that significantly affected 6 of 9 studied associations.

CONCLUSIONS

Intravenous fluids and analgesia significantly affect motility independent of severity and other covariates. Guidelines on prudent use of opioids and fluids in AP need to be developed, particularly taking into account duration of symptoms from onset to hospitalization.

Naldemedine versus placebo for opioid-induced constipation (COMPOSE-1 and COMPOSE-2): two multicentre, phase 3, double-blind, randomised, parallel-group trials

BACKGROUND

Opioid-induced constipation is a frequent side-effect of opioid treatment, and standard interventions have limited or inconsistent efficacy. This study assessed the efficacy and safety of naldemedine, a peripherally acting μ-opioid receptor antagonist, for the treatment of opioid-induced constipation in patients with chronic non-cancer pain.

METHODS

We report two double-blind, randomised, placebo-controlled trials in adults with chronic non-cancer pain and opioid-induced constipation. The first (COMPOSE-1) was done in 68 outpatient sites in seven countries and the second (COMPOSE-2) at 69 outpatient sites in six countries; both studies were done in Europe and the USA. Eligible patients were aged 18-80 years, did not use laxatives, and had a stable opioid regimen for treatment of chronic non-cancer pain with a total daily dose averaging at least 30 mg (morphine equivalent) for at least 1 month before screening. Patients were randomly assigned (1:1) to receive either oral naldemedine 0·2 mg or matching placebo once a day for 12 weeks. Randomisation was stratified by average total daily opioid dose (30-100 mg and >100 mg equivalents of oral morphine sulphate). The primary endpoint was proportion of responders. A responder had at least three spontaneous bowel movements (SBMs) per week with an increase from baseline of at least one SBM per week for at least 9 weeks of the 12-week treatment period including at least three of the last 4 weeks. Efficacy endpoints were analysed by intention to treat and the safety population included all patients who received at least one dose of study drug. These trials have both been completed and are registered with ClinicalTrials.gov, numbers NCT01965158 and NCT01993940.

FINDINGS

In COMPOSE-1, 547 patients were recruited between Aug 29, 2013, and Jan 22, 2015, and were randomly assigned to receive naldemedine (n=274) or placebo (n=273). Patients for COMPOSE-2 were recruited between Nov 4, 2013, and June 9, 2015; 553 patients were randomly assigned to receive naldemedine (n=277) or placebo (n=276). Five patients were enrolled at more than one site, so were excluded from the intention-to-treat population (COMPOSE-1: one per group; COMPOSE-2: one in the naldemedine group, two from the placebo group), with intention-to-treat group sizes of 273 in the naldemedine group and 272 in the placebo group in COMPOSE-1, and 276 in the naldemedine group and 274 in the placebo group in COMPOSE-2. The proportion of responders in both trials was significantly higher with naldemedine than with placebo in COMPOSE-1 (130 responders [47·6%] of 273 in the naldemedine group vs 94 responders [34·6%] of 272 in the placebo group, difference 13·0% [95% CI 4·8-21·3]; p=0·002) and in COMPOSE-2 (145 [52·5%] of 276 vs 92 [33·6%] of 274, difference 18·9% [10·8-27·0]; p<0·0001). Incidence of adverse events with naldemedine was similar to placebo (COMPOSE-1: 132 [49%] of 271 in the naldemedine group vs 123 [45%] of 272 in the placebo group; COMPOSE-2: 136 [50%] of 271 vs 132 [48%] of 274). Treatment-related adverse events were noted in 59 (22%) of 271 patients in the naldemedine group and 45 (17%) of 272 in the placebo group in COMOPOSE-1, and in 54 (20%) of 271 patients in the naldemedine group and 31 (11%) of 274 in the placebo group of COMPOSE-2; the between-group differences were largely due to gastrointestinal disorders, which were more common with naldemedine than placebo (COMPOSE-1: 40 [15%] patients in the naldemedine group vs 18 [7%] in the placebo group; COMPOSE-2: 42 [16%] vs 20 [7%]).

INTERPRETATION

Naldemedine treatment led to a significantly higher responder rate than did placebo and was generally well tolerated. These results support that naldemedine could be a new option for the treatment of opioid-induced constipation in patients with chronic non-cancer pain.

FUNDING

Shionogi & Co, Ltd.

Exploring acute-to-chronic neuropathic pain in rats after contusion spinal cord injury

Spinal cord injury (SCI) causes chronic pain in 65% of individuals. Unfortunately, current pain management is inadequate for many SCI patients. Rodent models could help identify how SCI pain develops, explore new treatment strategies, and reveal whether acute post-SCI morphine worsens chronic pain. However, few studies explore or compare SCI-elicited neuropathic pain in rats. Here, we sought to determine how different clinically relevant contusion SCIs in male and female rats affect neuropathic pain, and whether acute morphine worsens later chronic SCI pain. First, female rats received sham surgery, or 150kDyn or 200kDyn midline T9 contusion SCI. These rats displayed modest mechanical allodynia and long-lasting thermal hyperalgesia. Next, a 150kDyn (1s dwell) midline contusion SCI was performed in male and female rats. Interestingly, males, but not females showed SCI-elicited mechanical allodynia; rats of both sexes had thermal hyperalgesia. In this model, acute morphine treatment had no significant effect on chronic neuropathic pain symptoms. Unilateral SCIs can also elicit neuropathic pain that could be exacerbated by morphine, so male rats received unilateral T13 contusion SCI (100kDyn). These rats exhibited significant, transient mechanical allodynia, but not thermal hyperalgesia. Acute morphine did not exacerbate chronic pain. Our data show that specific rat contusion SCI models cause neuropathic pain. Further, chronic neuropathic pain elicited by these contusion SCIs was not amplified by our course of early post-trauma morphine. Using clinically relevant rat models of SCI could help identify novel pain management strategies.

Opioid-Related Constipation in Patients With Non-cancer Pain Syndromes: a Review of Evidence-Based Therapies and Justification for a Change in Nomenclature

PURPOSE OF REVIEW

Opioids are a mainstay in the treatment of chronic non-cancer pain syndromes, but their analgesic benefits come at a cost as opioid-related constipation occurs in 40-80% of individuals taking chronic opioids. Furthermore, as 10-20% of the population suffers from constipation at baseline, it should be expected that while a proportion of individuals will develop constipation as a direct consequence of opioids (OIC), others will experience it as an exacerbation of their baseline constipation (OEC). Herein, we review the evidence-based data for treatments directed at opioid-related constipation focusing on individuals with non-cancer pain syndromes and provide a template for the development of differentiated treatment algorithms for OIC and OEC.

RECENT FINDINGS

Historical and current treatment protocols recommend traditional laxatives, but these are ineffective in up to 50%, due in part to the heterogeneous pathogenesis of constipation. Therapeutic decisions must be tailored to account for this overlapping pathogenesis. OIC and OEC are distinct entities. As such, additional research and guidelines should address these as different patient populations.

Opioid analgesic use among patients presenting with acute abdominal pain and factors associated with surgical diagnoses

BACKGROUND

The prevalence of chronic opioid use among non-cancer patients presenting with acute abdominal pain (AAP) is unknown. The aim was to characterize opioid use, constipation, diagnoses, and risk factors for surgical diagnoses among non-cancer patients presenting with AAP to an emergency department (ED).

METHODS

We performed a retrospective, observational cohort study of all (n=16,121) adult patients (88% from MN, IA and WI) presenting during 2014 with AAP. We used electronic medical records, and focused on 2352 adults with AAP who underwent abdominal CT scan within 24 hours of presentation. We determined odds ratios of association with constipation and features predicting conditions that may require surgery (surgical diagnosis).

KEY RESULTS

There were 2352 eligible patients; 18.8% were opioid users. Constipation was more frequent in opioid (35.1%) compared to non-opioid users [OR 2.88 (95% CI 2.28, 3.62)]. Prevalence of surgical diagnosis in the opioid and non-opioid users was 35.3% and 41.7% respectively (P=.019). By univariate analysis, age and neutrophil count independently predicted increased risk, and chronic opioid use decreased risk of surgical diagnosis. Internal validation of logistic models using a randomly selected validation subset (25% of entire cohort, 587/2352) showed receiver operating characteristic (ROC) curves for the validation and full cohorts were similar.

CONCLUSIONS AND INFERENCES

Approximately 19% of adults presenting with AAP were opioid users; constipation is almost three times as likely in opioid users compared to non-opioid users presenting with AAP. Factors significantly associated with altered risk of surgical diagnoses were age, opioid use, and neutrophil count.

Phase IIb, Randomized, Double-Blind, Placebo-Controlled Study of Naldemedine for the Treatment of Opioid-Induced Constipation in Patients With Cancer

Purpose This randomized, double-blind, multicenter study aimed to determine the dose of naldemedine, a peripherally-acting μ-opioid receptor antagonist, for future trials by comparing the efficacy and safety of three doses of naldemedine versus placebo in patients with cancer and opioid-induced constipation. Methods Patients ≥ 18 years old with cancer, an Eastern Cooperative Oncology Group performance status ≤ 2, who had been receiving a stable regimen of opioid analgesics for ≥ 2 weeks, had at least one constipation symptom despite laxative use, and no more than five spontaneous bowel movements (SBMs) during the past 14 days, were randomly assigned (1:1:1:1) to oral, once-daily naldemedine 0.1, 0.2, or 0.4 mg, or placebo, for 14 days. The primary end point was change in SBM frequency per week from baseline during the treatment period. Secondary end points included SBM responder rates, change from baseline in the frequency of SBM without straining, and complete SBM. Safety was also assessed. Results Of 227 patients who were randomly assigned, 225 were assessed for efficacy (naldemedine 0.1 mg, n = 55; 0.2 mg, n = 58; 0.4 mg, n = 56; placebo, n = 56) and 226 for safety. Change in SBM frequency (primary end point) was higher with all naldemedine doses versus placebo ( P < .05 for all comparisons), as were SBM responder rates and change in complete SBM frequency. Change in SBM frequency without straining was significantly improved with naldemedine 0.2 and 0.4 (but not 0.1) mg versus placebo (at least P < .05). Treatment-emergent adverse events were more common with naldemedine (0.1 mg: 66.1%; 0.2 mg: 67.2%; 0.4 mg: 78.6%) than placebo (51.8%); the most common treatment-emergent adverse event was diarrhea. Conclusion Fourteen-day treatment with naldemedine significantly improved opioid-induced constipation in patients with cancer and was generally well tolerated. Naldemedine 0.2 mg was selected for phase III studies.

When People with Opioid-Induced Constipation Speak: A Patient Survey

Introduction

Opioid-induced constipation (OIC) is a common consequence of opioid use for chronic pain. OIC creates problems for patients independent of their pain syndromes, in addition to threatening pain treatment effectiveness. Healthcare practitioners need to be alert to how patients talk about OIC so that it is not missed. Using a survey mechanism, we sought patient expressions of the personal impact OIC imposes on how they are able to live their lives and on meanings that symptom relief would produce.

Methods

We used an online survey asking adults with OIC about quality of life implications of OIC and focused on open-ended text responses to questions about personal impacts of straining and meanings attached to OIC symptom relief. Participants were from the US, Canada, UK, Germany, Sweden, and Norway.

Results

A survey of 513 people with OIC produced 280 text responses concerning the impacts of straining on quality of life and 469 text responses on the meaning OIC symptom relief would confer. Text responses about the quality of life impacts of straining often included explicit descriptions conveying physical, psychological, or practical problems. Text responses about the meaning conferred from OIC symptom relief primarily concentrated around freedom from the constraints that OIC can impose.

Conclusions

Patients are willing and able to comment on the problems OIC cause them, using a variety of terms and phrases. Their comments concerning impacts on their lives will often refer to physical consequences, psychological effects, or practical implications. These insights provide healthcare practitioners guidance on how to engage patients about OIC.

Managing Constipation in Adults With Cancer

Constipation is common in individuals with cancer, occurring in almost 60% of patients overall. The incidence increases in patients with advanced disease, particularly in those receiving opioid analgesics or medications with anticholinergic properties. Constipation is not uniformly assessed and therefore not recognized and appropriately managed in many instances. This can increase patients' physical and psychological distress. Furthermore, there is scant research to support current management strategies for constipation. The objectives of this review are to explore the incidence of and risk factors for constipation in patients with cancer, to discuss the extent of the problem, to explore the nonpharmacologic and pharmacologic measures for constipation and fecal impaction, and to synthesize a laxative management. An extensive review of medical, pharmacy, and nursing literature was done to explore the physiology and pathogenesis of constipation; detail the mechanisms of action, onset of effect, approximate costs, and adverse effects of drugs for constipation; and condense clinical expert consensus recommendations for constipation, particularly in patients with cancer. Advanced practitioners (APs) and other clinicians play crucial roles in identifying individuals at risk for and experiencing constipation to help them use effective regimens, including over-the-counter laxatives, and perhaps adjunctive nondrug measures. Clinicians and patients must develop an agreed-upon language for identifying the severity and effects of constipation. In addition, both should understand which laxatives are most appropriate and which should be avoided for particular patients. Two prescription agents are also available, and understanding when they should be used is important for APs.

Healthcare resource use and costs of opioid-induced constipation among non-cancer and cancer patients on opioid therapy: A nationwide register-based cohort study in Denmark

BACKGROUND AND AIM

Opioid analgesics are often effective for pain management, but may cause constipation. The aim of this study was to determine healthcare resource use and costs in non-cancer and cancer patients with opioid-induced constipation (OIC).

METHODS

This was a nationwide register-based cohort study including patients ≥18 years of age initiating ≥4 weeks opioid therapy (1998-2012) in Denmark. A measure of OIC was constructed based on data from Danish national health registries, and defined as ≥1 diagnosis of constipation, diverticulitis, mega colon, ileus/subileus, abdominal pain/acute abdomen or haemorrhoids and/or ≥2 subsequent prescription issues of laxatives. Total healthcare resource utilization and costs (including pharmacy dispense, inpatient-, outpatient-, emergency room- and primary care) were estimated according to OIC status, opioid treatment dosage and length, gender, age, marital status, and comorbidities using Generalised Linear Model.

RESULTS

We identified 97169 eligible opioid users (77568 non-cancer and 19601 patients with a cancer diagnosis). Among non-cancer patients, 15% were classified with OIC, 10% had previous constipation, and 75% were without OIC. Patients characteristics of non-cancer OIC patients showed a higher frequency of strong opioid treatment (69% versus 41%), long-term opioid treatment (1189 days versus 584 days), advanced age (73 years versus 61 years), and cardiovascular disease (31% versus 19%) compared to those without OIC (P<0.001 for all comparisons). Non-cancer patients with OIC had 34% higher total healthcare costs compared to those without OIC (P<0.001) after adjusting for age, gender, opioid usage, marital status and comorbidities. Among cancer patients, 35% were classified with OIC, 14% had previous constipation, and 51% were without OIC. A higher proportion of cancer patients with OIC were continuous opioid users (85% versus 83%) and strong opioid users (97% versus 85%), compared to those without OIC (P<0.001 for both comparisons). Further, the mean number of days on opioids were higher for cancer patients with versus without OIC (329 days versus 238 days, P<0.001). Total healthcare costs were 25% higher for cancer patients with versus without OIC (P<0.001) after adjusting for age, gender, opioid usage, marital status and comorbidities.

CONCLUSIONS

The results of this nationwide study based on real life data suggested that both non-cancer patients and cancer patients suffering from opioid-induced constipation (OIC) may have higher healthcare resource utilization and higher associated costs compared to those without OIC.

IMPLICATIONS

Reducing the number of OIC patients has potential cost savings for the health care system. Special attention should be on patients at potential high risk of OIC, such as strong and long-term opioid treatment, advanced age, and concomitant cardiovascular disease.

Naloxegol in opioid-induced constipation: a new paradigm in the treatment of a common problem

Opioid-induced constipation (OIC) imposes a significant burden for patients taking pain medications, often resulting in decreased quality of life. Treatment of OIC with traditional medications for functional constipation can be incompletely effective, leading to nonadherence with opioid treatment and undertreated pain. An emerging class of medications that counteract the adverse effects of opioids in the gastrointestinal tract while preserving central nervous system-based pain relief may represent a paradigm shift in the prevention and treatment of OIC. One of these medications, naloxegol, is a once-daily, oral opioid antagonist that is effective, well-tolerated, and approved for treatment of OIC in patients with noncancer pain. More studies are needed to demonstrate this same utility in patients with cancer-related pain.

The efficacy of standard laxative use for the prevention and treatment of opioid induced constipation during oxycodone use: a small Dutch observational pilot study

BACKGROUND

Dutch clinical guidelines recommend that a standard laxative treatment (SLT) should be prescribed concomitantly when starting opioid treatment to prevent opioid-induced constipation (OIC).

METHODS

Clinical evidence for SLT in the treatment of OIC is lacking, therefore an observational pilot study was performed to explore the efficacy and tolerability of SLT on OIC in patients treated with the opioid oxycodone.

RESULTS

Twenty-four patients (58% female, median (range) age 65 (39-92)) were included in this pilot study. The analysis showed that 9 out of 21 patients (43%) were non-responders to SLT. When also taking into consideration patients tending to develop diarrhea 75% of patients are non-responsive to SLT.

CONCLUSION

This pilot study indicates that optimal laxative therapy (SLT) might not be effective and feasible for the prevention and treatment of OIC.

The Burden of Opioid-Induced Constipation: Discordance Between Patient and Health Care Provider Reports

BACKGROUND

Opioid-induced constipation (OIC), a common side effect of opioid treatment for chronic pain, affects patient health-related quality of life (HRQL) and may prompt some patients to lower the dose or alter adherence to their opioid medication, compromising pain relief. Although health care providers (HCPs) are aware of the potential for OIC, patients may not inform their HCPs of their OIC symptoms, and HCPs may not initiate conversation regarding OIC if their patients' pain is controlled. Patients often try to address OIC symptoms on their own by using natural approaches or over-the-counter options. When OIC is discussed in an office visit, HCPs typically recommend conventional laxatives to relieve symptoms, but the efficacy of this approach is unproven and often suboptimal. In many areas of medicine, HCP perceptions of the impact of adverse effects of treatment on a patient's HRQL do not align with the patient's experience.

OBJECTIVES

To (a) describe HCP-reported understanding of his or her patients' experiences with OIC and (b) evaluate the level of agreement or discordance in perception between patients and their HCPs of OIC's impact on clinical outcomes.

METHODS

This was a prospective, longitudinal, observational cohort study conducted in the United States, Canada, Germany, and the United Kingdom (NCT01928953) in patients aged 18 to 85 years who had been receiving daily opioid therapy for ≥ 4 weeks for chronic noncancer pain with presence of OIC in the past 2 weeks. Data were collected from retrospective chart reviews, HCP questionnaires, and web-based patient surveys. Eligible patients enrolled online and completed the Patient Assessment of Constipation-Symptoms, the Work Productivity and Activity Impairment Questionnaire-Specific Health Problem, the EuroQOL 5 Dimensions, and the Global Assessment of Treatment Benefit, Satisfaction, and Willingness to Continue standardized questionnaires. The patient-reported component included 1 baseline survey and 8 follow-up surveys over 24 weeks. HCPs completed a web-based survey at baseline and at week 24 to assess their perceptions of OIC burden, treatment patterns, laxative use, and overall treatment satisfaction. The correspondence of patient- and HCP-reported data was evaluated for all similar outcomes from these 2 databases.

RESULTS

Patients (N = 489) reported a mean (SD) number of bowel movements (BMs) per week and spontaneous BMs per week of 3.7 (2.9) and 1.4 (2.3), respectively, at baseline. Most (87%) reported chronic pain of ≥ 2 years duration; 65% had used opioids for ≥ 2 years; and the mean pain score at baseline was 6.3, consistent with a moderate-to-severe pain population. Most (97%) patients at baseline reported any gastrointestinal-related symptom of at least moderate intensity, with 82% reporting the same intensity of any symptom at week 24. Of the 405 patients who had seen their HCPs in the past month, 63% reported that they had spoken to their HCPs about constipation, and 62% reported that their HCPs had asked them if they had constipation in the past month. The proportion of agreement between HCPs and their patients on the presence of constipation at baseline was 61%. Similar average pain ratings between HCPs and patients (5.9 vs. 6.0) at week 24 suggested clear communication regarding the level of pain experienced by the patient; however, OIC symptoms, laxative use and effectiveness, and impact of OIC on pain management and HRQL were not fully appreciated by HCPs.

CONCLUSIONS

The importance and severity of OIC are perceived differently by patients and their HCPs, a discordance that complicates pain management and demonstrates a need for greater communication. These disparate perceptions indicate a need for clinical education and coordination of care by HCPs to improve understanding and proactively manage OIC in patients with chronic noncancer pain.

Efficacy and Safety of Methylnaltrexone for Opioid-Induced Constipation in Patients With Chronic Noncancer Pain: A Placebo Crossover Analysis

In patients with chronic noncancer pain, subcutaneous methylnaltrexone for opioid-induced constipation (OIC) was examined in a randomized controlled trial (RCT) followed by an open-label extension (OLE). This study examined the reproducibility of RCT findings by analyzing data from placebo-treated patients who crossed over to methylnaltrexone.

High prevalence of constipation and reduced quality of life in opioid-dependent patients treated with opioid substitution treatments

Objectives To evaluate prevalence and severity of constipation and quality of life (QoL) in a cohort of opioid-addicted patients treated with opioid substitution treatments (OST).

METHODS

A total of 1057 heroin-dependent patients treated with methadone or buprenorphine were enrolled in a multicenter observational study. Constipation was assessed by Wexner Constipation Scoring System (Wexner CSS), QoL by General Health Questionnaire (GHQ-12).

RESULTS

38.5% patients reported mild constipation, 33.3% reported moderate constipation, 14.8% severe constipation and 5.1% very severe constipation. Mean Wexner CSS score was 6.6 ± 4.8. 44.9% patients showed a GHQ-12 score ≥14; of these 18.3% patients showed a GHQ-12 score ≥20. Mean GHQ score was 13.8 ± 6.5. Mean Wexner CSS score was significantly higher in methadone patients (p = 0.004), in those taking psychoactive drugs (p = 0.0001) and in female (p < 0.0001) with respect to counterparts. Similarly, GHQ-12 mean scores were higher methadone group (p = 0.003), in those taking psychoactive drugs (p < 0.0001), and in female (p = 0.039) with respect to counterparts. ANOVA and ANCOVA showed a significant influence of methadone and female gender on Wexner CSS score while psychoactive drugs significantly influenced both tests.

CONCLUSIONS

The present study shows that patients affected by opioid-dependence in OST with methadone and buprenorphine have a high prevalence of constipation and reduced QoL.

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.

Opioidergic effects on enteric and sensory nerves in the lower GI tract: basic mechanisms and clinical implications

Opioids are one of the most prescribed drug classes for treating acute pain. However, chronic use is often associated with tolerance as well as debilitating side effects, including nausea and dependence, which are mediated by the central nervous system, as well as constipation emerging from effects on the enteric nervous system. These gastrointestinal (GI) side effects limit the usefulness of opioids in treating pain in many patients. Understanding the mechanism(s) of action of opioids on the nervous system that shows clinical benefit as well as those that have unwanted effects is critical for the improvement of opioid drugs. The opioidergic system comprises three classical receptors (μ, δ, κ) and a nonclassical receptor (nociceptin), and each of these receptors is expressed to varying extents by the enteric and intestinal extrinsic sensory afferent nerves. The purpose of this review is to discuss the role that the opioidergic system has on enteric and extrinsic afferent nerves in the lower GI tract in health and diseases of the lower GI tract, particularly inflammatory bowel disease and irritable bowel syndrome, and the implications of opioid treatment on clinical outcomes. Consideration is also given to emerging developments in our understanding of the immune system as a novel source of endogenous opioids and the mechanisms underlying opioid tolerance, including the potential influence of opioid receptor splice variants and heteromeric complexes.

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.

Prevalence and clinical features of opioid-induced constipation in the general population: A French study of 15,000 individuals

BACKGROUND

Constipation is common during opioid therapy and can compromise analgesia.

AIM

The aim of this article is to determine the prevalence and clinical characteristics of opioid-induced constipation (OIC) in France.

METHODS

A questionnaire study was conducted in a representative sample of the French general population. Participants completed a 31-item questionnaire covering opioid use during the previous six months, and the occurrence of constipation (defined as <3 bowel movements per week, straining during defaecation, or both) during opioid treatment.

RESULTS

Data were obtained from 15,213 participants, of whom 4753 (31.2%) reported opioid use. Most analgesics (96.5%) were classified as World Health Organization step II analgesics, and the remainder were step III. The most common indications for opioids were bone or joint pain, and soft tissue pain. Overall, 414/4753 (8.7%) opioid users reported OIC while the prevalence of OIC reached 21% in case of regular or prolonged (>1 month) opioid use. Other characteristics associated with OIC included female gender, age ≥50 years and use of step III opioids. Only 177/414 (42.8%) participants with OIC had used medications (most commonly osmotic laxatives) to treat constipation, and satisfaction with constipation medication was moderate (mean (SD) score 7.2 (1.3) on a scale of 0-10).

CONCLUSIONS

Approximately one-third of a representative French population had used opioids within the previous six months, and 9% of users had experienced OIC, which is more frequent in case of regular use. OIC appears to be under-treated, and participants' satisfaction with their constipation medications was only moderate, suggesting that significant unmet need remains in OIC management.

New Options in Constipation Management

Constipation is common in the general population and for those on opioids and/or who are suffering from advanced cancer. Self-management consists of dietary changes, exercise, and laxatives. However, responses to self-management efforts are often inadequate to relieve the subjective and objective experience of constipation. Multiple new anti-constipating medications have recently been tested in randomized trials and the following are available commercially: probiotics, prucalopride, lubiprostone, linaclotide, elobixibat, antidepressants, methylnaltrexone, alvimopan, and naloxegol. This review will discuss the evidence-based benefits of these medications and outline an approach to managing constipation.

Targeting inflammation as a treatment modality for neuropathic pain in spinal cord injury: a randomized clinical trial

Background

The purpose of the present study was to examine the effectiveness of an anti-inflammatory intervention as a treatment for neuropathic pain following spinal cord injury (SCI).

Methods

This randomized, parallel-group, controlled clinical trial (NCT02099890) examined 20 participants with varying levels and severities of SCI, randomized (3:2) to either a 12-week anti-inflammatory diet, or control group. Outcome measures consisted of self-determined indices of pain as assessed using the neuropathic pain questionnaire (NPQ) and markers of inflammation as assessed by various pro- and anti-inflammatory cytokines, as well as the eicosanoids PGE2 and LTB4.

Results

A significant group × time interaction was found for sensory pain scores (p < 0.01). A Mann-Whitney test revealed that the change scores (3-month baseline) were significantly different between groups for IFN-y (U = 13.0, p = 0.01), IL-1β (U = 14.0, p = 0.01), and IL-2 (U = 12.0, p = 0.01). A Friedman test revealed the treatment group had a significant reduction in IFN-y (x² = 8.67, p = 0.01), IL-1β (x² = 17.78, p < 0.01), IL-6 (x² = 6.17, p < 0.05), while the control group showed no significant change in any inflammatory mediator. A stepwise backward elimination multiple regression analysis showed that the change in sensory neuropathic pain was a function of the change in the proinflammatory cytokines IL-2 and IFN-y, as well as the eicosanoid PGE2 (R = 0.689, R² = 0.474).

Conclusions

Overall, the results of the study demonstrate the efficacy of targeting inflammation as a means of treating neuropathic pain in SCI, with a potential mechanism relating to the reduction in proinflammatory cytokines and PGE2.

Trial registration

ClinicalTrials.gov, NCT02099890

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0625-4) contains supplementary material, which is available to authorized users.

Symptom clustering in hospitalised older palliative cancer patients: A cross-sectional study

BACKGROUND

Accurate detection of symptoms is essential in palliative care. Identification of clustering of symptom is valuable to develop target interventions. This area is largely understudied in older palliative cancer patients.

OBJECTIVES

To identify symptom clustering in older palliative cancer patients, and patient groups based on the clustering of symptoms, and to evaluate the difference in functional dependence and experiencing life as not meaningful between the identified patient groups.

DESIGN

A cross-sectional study.

SETTING

Geriatric and non-geriatric wards of seven acute care hospitals.

PARTICIPANTS

400 palliative cancer patients aged 65 years and older.

METHODS

Symptoms were collected using a validated instrument which assesses physical, psychological, functional, social, and existential symptoms by means of a structured interview with a researcher. An agglomerative hierarchical clustering analysis was used to analyse the data.

RESULTS

The cluster analysis revealed five groups of symptoms: (1) urological and gastrointestinal symptoms, and their treatment complications, (2) psychological and existential symptoms, (3) pain, constipation, sleeplessness and airway problems, (4) functionality problems, and (5) fatigue-related symptoms. Three patient groups were identified: (1) symptom-free group, (2) physical discomfort group, and (3) physical and psychological discomfort group. In the last group, significant more patients had a geriatric risk profile and less of them received chemotherapy. Patients in this group were more often functionally dependent and experienced their life as not meaningful.

CONCLUSION

Five groups of symptoms were identified. Three patient groups were identified which reported different levels of functionality and experiencing life as meaningful. Healthcare professionals should be triggered to detect symptom clusters and be alert to the presence of the other symptoms in the cluster when identifying one symptom. They should also be alert to patients with a geriatric risk profile because of their higher risk of experiencing physical and psychological symptoms and the influence these symptoms have on being functionally dependent and experiencing life as not meaningful.

An appraisal of clinical practice guidelines for constipation: a right attitude towards to guidelines

Background

Clinical practice guidelines (CPGs) are formally developed statements that assist users to provide proper health care for a kind of disease and play a significant contribution in healthcare system. This study report the methodological quality of CPGs on constipation.

Methods

The “Appraisal of Guidelines and Research and Evaluation” (AGREEII) instrument was developed to determine the quality of CPGs. A comprehensive search was developed using five databases and three guideline websites until/up to December, 2015. Four independent authors evaluated the methodological issues of the CPGs by the AGREEII instrument.

Results

We identified 22 relevant guidelines on constipation from 1234 citations. The overall agreement among evaluators was 0.84 using the intra-class correlation coefficient. The mean AGREEII scores for the domains “scope and purpose” (51.77) and “rigor of development” (56.73) were moderate; afterward, three domains “stakeholder involvement” (32.23), “editorial independence” (29.59) and “applicability” (29.14) were low scores. The “clarity and presentation” (23.73) had the lowest scores.

Conclusion

Although existing constipation guidelines may accurately reflect current clinical practices, many guidelines’ methodological quality is low. Therefore, more emphasis and attentions should be taken to the development of high-quality guidelines.

Diagnosis and management of chronic constipation in adults

Constipation is a heterogeneous, polysymptomatic, multifactorial disease. Acute or transient constipation can be due to changes in diet, travel or stress, and secondary constipation can result from drug treatment, neurological or metabolic conditions or, rarely, colon cancer. A diagnosis of primary chronic constipation is made after exclusion of secondary causes of constipation and encompasses several overlapping subtypes. Slow-transit constipation is characterized by prolonged colonic transit in the absence of pelvic floor dysfunction. This subtype of constipation can be identified using either the radio-opaque marker test or wireless motility capsule test, and is best treated with laxatives such as polyethylene glycol or newer agents such as linaclotide or lubiprostone. If unsuccessful, subspecialist referral should be considered. Dyssynergic defecation results from impaired coordination of rectoanal and pelvic floor muscles, and causes difficulty with defecation. The condition can be identified using anorectal manometry and balloon expulsion tests and is best managed with biofeedback therapy. Opioid-induced constipation is an emerging entity, and several drugs including naloxegol, methylnaltrexone and lubiprostone are approved for its treatment. In this Review, we provide an overview of the burden and pathophysiology of chronic constipation, as well as a detailed discussion of the available diagnostic tools and treatment options.

Safety concerns with long-term opioid use

INTRODUCTION

The benefits of opioid therapy must be balanced by any adverse effects. In recent years, prescription opioids have been increasingly prescribed, but have also been associated with increased abuse, overdose and death.

AREAS COVERED

This review will categorize the common risks of opioid administration. Recognized adverse effects of opioid therapy include constipation, tolerance, endocrinopathies, sleep disorders, cognitive effects, respiratory depression, overdose and addiction. Studies have shown that there is increased risk of overdose and death with higher daily opioid doses, particularly above a morphine equivalent oral daily dose of 100 milligrams. Extended-release/long acting (ER/LA) opioid formulations may be beneficial for the compliant patient, yet may expose a higher risk for abuse if used inappropriately since each tablet carries a larger dose of medication.

EXPERT OPINION

Prospective, controlled one-year trials are needed to establish the efficacy and safety profile of chronic opioid therapy. In addition to the well known side effects of chronic opioid therapy, the influence and serious effect of opioids on sleep and central sleep apnea is only recently being investigated. The lowest possible daily opioid must be used to manage chronic pain, and all clinicians should be cautious in the use of daily morphine equivalent doses above 50-100 milligrams.

Opioid-induced constipation, use of laxatives, and health-related quality of life

Background and aims

Real-life data on laxative use in patients suffering from opioid-induced constipation (OIC) are very limited, and many OIC patients are only using over the counter laxatives to resolve their constipation. Our aim was to describe laxative utilization and quality of life in participants in Norway who ever experienced OIC.

Methods

This was a cross-sectional online survey conducted between 27th of June and 3rd of July 2014 among participants above 18 years with self-reported OIC and who had agreed to receive information from the pharmacy chain (Boots A/S, Norway). The questionnaire comprised a series of multiple choice, close-ended, and free text questions on abdominal symptoms, laxative use and health-related quality of life.

Results

A total of 417 participants met the study eligibility criteria: (1) treated with opioid for a minimum of 4 weeks, (2) actively accepted participation, and (3) confirmed ever experiencing OIC and in addition completed the survey. Among the eligible participants, 86% were females, 85% were younger than 60 years of age, and 57% were currently suffering OIC. More than half of the currently constipated participants were experiencing moderate to very severe abdominal bloating (63%), abdominal pain (55%) and/or pain during bowel movement (50%). Less than every fourth participant (23%) had consulted health care professionals (HCPs) about their constipation. Up to 39% reported that they handled their OIC by self-management, e.g., bought laxative, reduced the dose and/or changed opioid without consulting HCP or pharmacy. Less than half (48%) of the laxative users were satisfied with the laxative they were using to relieve their constipation. The EQ-5D health-related quality of life score was mean (SD): 0.587 (0.272). Although not statistically significant (p = 0.067), there was a tendency of lower quality of life among the participants who were currently constipated compared with those not currently constipated (difference of mean EQ-5D: 0.629-0.555 = 0.074). A significantly lower (p = 0.001) quality of life was found among participants who were dissatisfied with their laxative [mean (SD): 0.424 (0.350)] than among those who were satisfied or neither satisfied nor dissatisfied [mean (SD): 0.628 (0.235) and 0.673 (0.155), respectively].

Conclusions

The results suggest a high degree of moderate to very severe abdominal symptoms, a high degree of self-management of opioid-induced constipation, a low degree of satisfaction with laxative, and low health-related quality of life of patients suffering from chronic pain necessitating long-term opioid treatment, subsequent constipation and laxatives use.

Implications

Patients suffering from OIC with low quality of life and remaining symptoms despite use of two or more laxatives are a vulnerable patient group in need of optimized healthcare management, who also might benefit from more specific and innovative therapy.

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.

Opioid-Induced Constipation Survey in Patients with Chronic Noncancer Pain

Chronic pain patients relying on chronic opioid therapy are often challenged with opioid-induced constipation (OIC), a difficult condition to treat that has a significant psychosocial impact on those who are affected (Bruner et al., J Pain Res, 8, 2015, 289). Unlike other side effects of opioids, OIC does not resolve over time during chronic opioid use, and treatments used for functional constipation often fail to provide adequate symptom relief (Nelson and Camilleri, Therap Adv Gastroenterol, 8, 2015, 206). Estimates of the prevalence of OIC vary. It has been reported that 15% to 90% of opioid users are affected by OIC (Gaertner et al., J Clin Gastroenterol, 49, 2015, 9; Wan et al., Am Health Drug Benefits, 8, 2015, 93; Coyne et al., Clinicoecon Outcomes Res, 6, 2014, 269). In addition, a recent rise in opioid prescriptions by nonpain specialists has contributed to the increase in opioid-related side effects, such as OIC (Nelson and Camilleri, Therap Adv Gastroenterol, 8, 2015, 206; Tuteja et al., Neurogastroenterol Motil, 22, 2010, 424). We conducted a survey on OIC through PainPathways magazine in fall of 2014 and in spring of 2015. Survey results showed the prevalence of depression and the modification of opioid dosage were higher than previously thought. Additionally, we found that discussions with healthcare workers regarding OIC do not take place regularly. Our results re-emphasize the need for a consensus on OIC-specific diagnostic criteria, evidence-based treatment strategies, outcome metrics, and education about OIC for both prescribers and patients to improve clinical outcome as well as patient satisfaction.

Novel Oral Therapies for Opioid-induced Bowel Dysfunction in Patients with Chronic Noncancer Pain

Opioid analgesics are frequently prescribed and play an important role in chronic pain management. Opioid-induced bowel dysfunction, which includes constipation, hardened stool, incomplete evacuation, gas, and nausea and vomiting, is the most common adverse event associated with opioid use. Mu-opioid receptors are specifically responsible for opioid-induced bowel dysfunction, resulting in reduced peristaltic and secretory actions. Agents that reverse these actions in the bowel without reversing pain control in the central nervous system may be preferred over traditional laxatives. The efficacy and safety of these agents in chronic noncancer pain were assessed from publications identified through Ovid and PubMed database searches. Trials that evaluated the safety and efficacy of oral agents for opioid-induced constipation or opioid-induced bowel dysfunction, excluding laxatives, were reviewed. Lubiprostone and naloxegol are approved in the United States by the Food and Drug Administration for use in opioid-induced constipation. Axelopran (TD-1211) and sustained-release naloxone have undergone phase 2 and phase 1 studies, respectively, for the same indication. Naloxegol and axelopran are peripherally acting μ-opioid receptor antagonists. Naloxone essentially functions as a peripherally acting μ-opioid receptor antagonist when administered orally in a sustained-release formulation. Lubiprostone is a locally acting chloride channel (CIC-2) activator that increases secretions and peristalsis. All agents increase spontaneous bowel movements and reduce other bowel symptoms compared with placebo in patients with noncancer pain who are chronic opioid users. The most common adverse events were gastrointestinal in nature, and none of the drugs were associated with severe adverse or cardiovascular events. Investigations comparing these agents to regimens using standard laxative and combination therapy and trials in special populations and patients with active cancer are needed to further define their role in therapy.

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.

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.

Opioid-induced constipation: advances and clinical guidance

Currently opioids are the most frequently used medications for chronic noncancer pain. Opioid-induced constipation is the most common adverse effect associated with prolonged use of opioids, having a major impact on quality of life. There is an increasing need to treat opioid-induced constipation. With the recent approval of medications for the treatment of opioid-induced constipation, there are several therapeutic approaches. This review addresses the clinical presentation and diagnosis of opioid-induced constipation, barriers to its diagnosis, effects of opioids in the gastrointestinal tract, differential tolerance to opiates in different gastrointestinal organs, medications approved and in development for the treatment of opioid-induced constipation, and a proposed clinical management algorithm for treating opioid-induced constipation in patients with noncancer pain.

Naloxegol: a review of its use in patients with opioid-induced constipation

Oral naloxegol (Movantik™, Moventig(®)), a peripherally acting μ-opioid receptor antagonist, inhibits opioid binding in μ-opioid receptors in the gastrointestinal tract. This article reviews the pharmacological properties of naloxegol and its clinical efficacy and tolerability in patients with opioid-induced constipation. It demonstrated clinical efficacy and was well tolerated in placebo-controlled trials in patients with non-cancer pain and opioid-induced constipation, including those with an inadequate response to laxatives, and was well tolerated in a long-term safety study. As a PEGylated naloxone derivative, naloxegol is associated with significant improvements in spontaneous bowel movements, while maintaining levels of opioid-related analgesia (a result of its reduced ability to cross the blood-brain barrier). Naloxegol is a useful option in the treatment of opioid-induced constipation.

Absorption, distribution, metabolism, and excretion of [14C]-labeled naloxegol in healthy subjects

Objective: To characterize the absorption, distribution, metabolism, and excretion of naloxegol, a PEGylated derivative of the µ-opioid antagonist naloxone, in healthy male subjects. Materials and methods: [¹⁴C]-Labeled naloxegol (27 mg, 3.43 MBq) was administered as an oral solution to 6 fasted subjects. Blood, fecal, and urine samples were collected predose and at various intervals postdose. Naloxegol and its metabolites were quantified or identified by liquid chromatography with radiometric or mass spectrometric detection. Pharmacokinetic parameters were calculated for each subject, and metabolite identification was performed by liquid chromatography with parallel radioactivity measurement and mass spectrometry. Results: Naloxegol was rapidly absorbed, with a maximum plasma concentration (geometric mean) of 51 ng/mL reached before 2 hours after dosing. A second peak in the observed naloxegol and [¹⁴C] plasma concentration-time profiles was observed at ~ 3 hours and was likely due to enterohepatic recycling of parent naloxegol. Distribution to red blood cells was negligible. Metabolism of [¹⁴C]-naloxegol was rapid and extensive and occurred via demethylation and oxidation, dealkylation, and shortening of the polyethylene glycol chain. Mean cumulative recovery of radioactivity was 84.2% of the total dose, with ~ 68.9% recovered within 96 hours of dosing. Fecal excretion was the predominant route of elimination, with mean recoveries of total radioactivity in feces and urine of 67.7% and 16.0%, respectively. Unchanged naloxegol accounted for ~ 1/4 of the radioactivity recovered in feces. Conclusions: Naloxegol was rapidly absorbed and cleared via metabolism, with predominantly fecal excretion of parent and metabolites.

Consensus Recommendations on Initiating Prescription Therapies for Opioid-Induced Constipation

Objective

Aims of this consensus panel were to determine (1) an optimal symptom‐based method for assessing opioid‐induced constipation in clinical practice and (2) a threshold of symptom severity to prompt consideration of prescription therapy.

Methods

A multidisciplinary panel of 10 experts with extensive knowledge/experience with opioid‐associated adverse events convened to discuss the literature on assessment methods used for opioid‐induced constipation and reach consensus on each objective using the nominal group technique.

Results

Five validated assessment tools were evaluated: the Patient Assessment of Constipation–Symptoms (PAC‐SYM), Patient Assessment of Constipation–Quality of Life (PAC‐QOL), Stool Symptom Screener (SSS), Bowel Function Index (BFI), and Bowel Function Diary (BF‐Diary). The 3‐item BFI and 4‐item SSS, both clinician administered, are the shortest tools. In published trials, the BFI and 12‐item PAC‐SYM are most commonly used. The 11‐item BF‐Diary is highly relevant in opioid‐induced constipation and was developed and validated in accordance with US Food and Drug Administration guidelines. However, the panel believes that the complex scoring for this tool and the SSS, PAC‐SYM, and 28‐item PAC‐QOL may be unfeasible for clinical practice. The BFI is psychometrically validated and responsive to changes in symptom severity; scores range from 0 to 100, with higher scores indicating greater severity and scores >28.8 points indicating constipation.

Conclusions

The BFI is a simple assessment tool with a validated threshold of clinically significant constipation. Prescription treatments for opioid‐induced constipation should be considered for patients who have a BFI score of ≥30 points and an inadequate response to first‐line interventions.

Efficacy and safety of naloxegol in patients with opioid-induced constipation and laxative-inadequate response

BACKGROUND

Treatment options for patients with opioid-induced constipation (OIC) and inadequate response to laxatives (LIR) are few.

OBJECTIVE

Assess the efficacy and safety of orally administered naloxegol in patients with prospectively confirmed OIC and LIR.

METHODS

We analyzed pooled data from two identical randomized, double-blind, placebo-controlled, Phase 3 trials of naloxegol in patients with non-cancer pain, OIC and LIR in which naloxegol (12.5 mg, n = 240; 25 mg, n = 241) or placebo (n = 239) were administered daily. We assessed the response rates, time to first post-dose laxation, spontaneous bowel movements (SBMs), OIC symptoms and patient-reported outcomes over 12 weeks.

RESULTS

OIC response rates for the naloxegol 25-mg (p < 0.001) and the 12.5-mg (p = 0.005) LIR dose groups were higher than placebo. Median times to first post-dose SBM were 7.6, 19.2 and 41.1 hours for the naloxegol 25 mg, naloxegol 12.5 mg and placebo groups, respectively. Other SBM measures, daily symptoms of OIC, and both the Patient Assessment of Constipation - Symptoms and Patient Assessment of Constipation-Quality of Life scores improved from baseline with naloxegol treatment. Changes from baseline in opioid dose, pain scores and opioid withdrawal scores were similar among treatment groups.

CONCLUSIONS

Naloxegol was efficacious, generally safe and well tolerated in the patients with OIC and LIR, while preserving opioid analgesia. ClinicalTrials.gov identifiers: NCT01309841; NCT01323790.

Evolving paradigms in the treatment of opioid-induced bowel dysfunction

In recent years prescription of opioids has increased significantly. Although effective in pain management, bothersome gastrointestinal adverse effects are experienced by a substantial proportion of opioid-treated patients. This can lead to difficulties with therapy and subsequently inadequate pain relief. Collectively referred to as opioid-induced bowel dysfunction, these adverse effects are the result of binding of exogenous opioids to opioid receptors in the gastrointestinal tract. This leads to disturbance of three important gastrointestinal functions: motility, coordination of sphincter function and secretion. In the clinic this manifests in a wide range of symptoms such as reflux, bloating, abdominal cramping, hard, dry stools, and incomplete evacuation, although the most known adverse effect is opioid-induced constipation. Traditional treatment with laxatives is often insufficient, but in recent years a number of novel pharmacological approaches have been introduced. In this review the pathophysiology, symptomatology and prevalence of opioid-induced bowel dysfunction is presented along with the benefits and caveats of a suggested consensus definition for opioid-induced constipation. Finally, traditional treatment is appraised and compared with the latest pharmacological developments. In conclusion, opioid antagonists restricted to the periphery show promising results, but use of different definitions and outcome measures complicate comparison. However, an international working group has recently suggested a consensus definition for opioid-induced constipation and relevant outcome measures have also been proposed. If investigators within this field adapt the suggested consensus and include symptoms related to dysfunction of the upper gut, it will ease comparison and be a step forward in future research.