Efficacy and safety of prucalopride in patients with chronic noncancer pain suffering from opioid-induced constipation

Emerging therapies for opioid-induced constipation: what can we expect?

INTRODUCTION

The rise in opioid use for managing chronic and oncologic pain has led to a significant increase in opioid-induced constipation (OIC) that impacts patient quality of life and pain management.

AREAS COVERED

In this study, emerging therapies for OIC were criticized for refining advancements and novel treatment options. Key topics included the efficacy of peripherally acting mu-opioid receptor antagonists (PAMORAs) such as methylnaltrexone, naloxegol, and naldemedine, which specifically target opioid-induced gut dysfunction. Other treatment options, including intestinal secretagogues like lubiprostone and linaclotide, selective 5-HT receptor agonists such as prucalopride, and emerging adjunctive therapies like transcutaneous electrical nerve stimulation (TENS) and electroacupuncture were mentioned. Current guidelines from the American Gastroenterological Association (AGA) and the European consensus were criticized.

EXPERT OPINION

Experts stress the importance of a stepwise approach to managing OIC, considering patient-specific factors and the efficacy of various treatments. While PAMORAs have demonstrated effectiveness in improving bowel function, their high cost and lack of extensive head-to-head comparisons with traditional laxatives are significant concerns. Emerging therapies and adjunctive treatments offer promising results but require further validation through rigorous studies. Future research should focus on long-term outcomes, cost-effectiveness, and comparative effectiveness to better address the complex needs of patients with OIC and refine treatment protocols.

Prokinetics-safety and efficacy: The European Society of Neurogastroenterology and Motility/The American Neurogastroenterology and Motility Society expert review

BACKGROUND

Prokinetics are a class of pharmacological drugs designed to improve gastrointestinal (GI) motility, either regionally or across the whole gut. Each drug has its merits and drawbacks, and based on current evidence as high-quality studies are limited, we have no clear recommendation on one class or other. However, there remains a large unmet need for both regionally selective and/or globally acting prokinetic drugs that work primarily intraluminally and are safe and without systemic side effects.

PURPOSE

Here, we describe the strengths and weaknesses of six classes of prokinetic drugs, including their pharmacokinetic properties, efficacy, safety and tolerability and potential indications.

Patient-Reported Outcomes in Disorders of Gut-Brain Interaction

Disorders of gut-brain interaction are characterized by chronic gastrointestinal symptoms in the absence of abnormal endoscopic or radiologic findings or objective biomarkers that can be identified during routine clinical evaluation. The assessment of the symptom pattern and severity, therefore, is the key modality to evaluate the presence, impact, and evolution of these conditions, for both clinical and regulatory purposes. Patient-reported outcomes are structured symptom assessment questionnaires designed to evaluate symptom patterns, quantify severity of symptoms, and evaluate response to treatment at follow-up. This review provides an overview of currently available patient-reported outcomes for evaluating the main disorders of gut-brain interaction, specifically, functional dyspepsia; irritable bowel syndrome; and chronic constipation. It summarizes their content, level of validation for clinical practice and for research, and the regulatory approach to these conditions. Expected future developments and need for further research on patient-reported outcomes for these and other disorders of gut-brain interaction are highlighted.

Constipation in Cancer Patients - an Update of Clinical Evidence

OPINION STATEMENT

Constipation is one of the most frequent problems in cancer patients, and its etiology is multifactorial. It leads to decreased quality of life and impedes optimal pain treatment. Despite the high prevalence, constipation is frequently underdiagnosed mainly because of lack of validated diagnostic criteria or widely accepted definition of constipation in cancer patients. All cancer patients should be evaluated regularly for constipation, and concomitant causes and risk factors were assessed. Opioids are responsible for a much of the secondary constipation in cancer patients. The management of constipation in cancer patients should be multifaceted, addressing dietary and behavioral issues and optimizing pharmacological interventions. Prevention of opioid-induced constipation (OIC) is pivotal, as treatment is often unsatisfactory or inefficient. Dietary and behavioral interventions should be considered. Non-pharmacological measures include hydration and nutrition, ensuring privacy during defecation, using a commode or footstool, and the availability of a caregiver. Abdominal massage may be of value. Traditional laxatives are recommended in prevention but not in the treatment of OIC. Peripherally acting mu-opioid receptor antagonists (PAMORA) appear the first choice in the treatment and an alternative to laxatives in some recent clinical practice guidelines in preventing OIC. Naldemedine, naloxegol, and methylnaltrexone are supported by quality evidence for OIC management. Naloxone or naltrexone, taken orally in combined formulations with opioids, may be valuable in preventing or reducing OIC symptoms.

Opioid-Related Constipation

Opioid-related constipation encompasses constipation directly caused by opioid use (opioid-induced constipation [OIC]) as well as pre-existing constipation worsened by opioid use (opioid-exacerbated constipation [OEC]). Over-the-counter laxatives should be used as first-line agents for both OIC and OEC, given their efficacy, low cost, and high safety profiles. Symptoms of OIC and responses to therapy can be assessed with the Bowel Function Index. Individuals with OIC refractory to laxatives may be responsive to peripherally acting μ-opioid receptor antagonists. Although data supporting the superiority of one prescription agent over another is lacking, all have proven effective for the treatment of OIC.

Clinical and Nonclinical Disposition and In Vitro Drug-Drug Interaction Potential of Felcisetrag, a Highly Selective and Potent 5-HT4 Receptor Agonist

BACKGROUND AND OBJECTIVE

Felcisetrag (previously TAK-954 or TD-8954) is a highly selective and potent 5-HT₄ receptor agonist in clinical development for prophylaxis and treatment of postoperative gastrointestinal dysfunction (POGD). The rat, dog, and human absorption, distribution, metabolism, and excretion (ADME) properties of felcisetrag were investigated.

METHODS

The metabolism and victim and perpetrator drug interaction potentials towards cytochrome P450s (CYP) and transporters were determined using in vitro models. The excretion, metabolite profile, and pharmacokinetics were determined during unlabeled and radiolabeled ADME studies in rat and dog for comparison with human. Due to a low clinical dose (0.5 mg) and radioactivity (~ 1.5 μCi), a combination of liquid scintillation counting and accelerator mass spectrometry was used for analysis of samples in this study.

RESULTS

The ADME properties, including metabolite profile, for felcisetrag are generally conserved across species. Felcisetrag is primarily cleared through renal excretion (0.443) and metabolism in humans (0.420), with intact parent as the predominant species in circulation. There are multiple metabolites, each representing < 10% of the circulating radioactivity, confirming no metabolites in safety testing (MIST) liabilities. Metabolites were also detected in animals. The potential for major CYP- and transporter-based drug-drug interaction (DDI) of felcisetrag as a victim or perpetrator is considered to be low.

CONCLUSIONS

Felcisetrag is primarily cleared in humans through renal excretion. Although the metabolism of felcisetrag is primarily through CYP3A, the potential for clinically relevant DDI as a victim is significantly reduced as metabolism plays a minor role in the overall clearance.

Naldemedine Improves Patient-Reported Outcomes of Opioid-Induced Constipation in Patients with Chronic Non-Cancer Pain in the COMPOSE Phase 3 Studies

Objective

Opioid-induced constipation is among the most common side effects associated with opioid use in patients with chronic non-cancer pain, and it can have a significant negative impact on health-related quality of life (QOL). This analysis evaluated the effect of naldemedine 0.2 mg on patient-reported outcomes in three phase 3 clinical studies.

Methods

COMPOSE-1 and COMPOSE-2 were identical randomized, double-blind, placebo-controlled, parallel-group studies of 12 weeks’ duration, allowing data to be integrated (n=1095). COMPOSE-3 was similar in design, but of 52 weeks’ duration (n=1241). Patients were adults with chronic non-cancer pain who had been treated with opioid analgesics for ≥3 months and experiencing opioid-induced constipation. Patient-reported outcomes included Patient Assessment of Constipation Symptoms (PAC-SYM; 12 questions assessed on a 5-point Likert scale), PAC-QOL (28 questions assessed on a 5-point Likert scale), and Subject Global Satisfaction (measured on a 7-point Likert scale). The proportion of patients achieving a ≥1.5 improvement in PAC-SYM and PAC-QOL was calculated. The correlation between change in PAC-SYM and PAC-QOL scores and frequency of bowel movements was also explored.

Results

The proportion of PAC-SYM and PAC-QOL responders was significantly higher for naldemedine than for placebo at all assessed time points in COMPOSE-1/COMPOSE-2 (p<0.005 for both) and COMPOSE-3 (p<0.005 and p<0.0001, respectively). There was a statistically significant correlation between improvement in PAC-SYM/PAC-QOL and frequency of bowel movements at all time points (p≤0.0002). The majority of patients treated with naldemedine reported markedly or moderately improved satisfaction with constipation and abdominal symptoms on the Subject Global Satisfaction questionnaire.

Discussion

Naldemedine treatment was associated with a rapid and sustained clinically relevant improvement in patient-reported outcomes, indicating improvement in opioid-induced constipation-related symptoms and QOL.

ClinicalTrials.gov Registration

NCT01965158, NCT01993940, NCT01965652.

Management of Opioid-Induced Constipation and Bowel Dysfunction: Expert Opinion of an Italian Multidisciplinary Panel

The prescribing and use of opioid analgesics is increasing in Italy owing to a profusion in the number and types of opioid analgesic products available, and the increasing prevalence of conditions associated with severe pain, the latter being related to population aging. Herein we provide the expert opinion of an Italian multidisciplinary panel on the management of opioid-induced constipation (OIC) and bowel dysfunction. OIC and opioid-induced bowel dysfunction are well-recognised unwanted effects of treatment with opioid analgesics that can profoundly affect quality of life. OIC can be due to additional factors such as reduced mobility, a low-fibre diet, comorbidities, and concomitant medications. Fixed-dose combinations of opioids with mu (μ) opioid receptor antagonists, such as oxycodone/naloxone, have become available, but have limited utility in clinical practice because the individual components cannot be independently titrated, creating a risk of breakthrough pain as the dose is increased. A comprehensive prevention and management strategy for OIC should include interventions that aim to improve fibre and fluid intake, increase mobility or exercise, and restore bowel function without compromising pain control. Recommended first-line pharmacological treatment of OIC is with an osmotic laxative (preferably polyethylene glycol [macrogol]), or a stimulant laxative such as an anthraquinone. A second laxative with a complementary mechanism of action should be added in the event of an inadequate response. Second-line treatment with a peripherally acting μ opioid receptor antagonist (PAMORA), such as methylnaltrexone, naloxegol or naldemedine, should be considered in patients with OIC that has not responded to combination laxative treatment. Prokinetics or intestinal secretagogues, such as lubiprostone, may be appropriate in the third-line setting, but their use in OIC is off-label in Italy, and should therefore be restricted to settings such as specialist centres and clinical trials.

Current Opinion on Prucalopride in Gastroparesis and Chronic Constipation Treatment: A Focus on Patient Selection and Safety

Prucalopride is a third-generation, highly selective 5-hydroxytryptamine 4 (5-HT4) receptor agonist. Many recent studies indicate prucalopride may play an important role in various motility disorders. The aim of this study was to investigate safety and patient selection considerations when using prucalopride as gastroparesis and chronic constipation treatment. We systematically searched PubMed, Embase, the Cochrane Central Register and ClinicalTrials.gov, and we reviewed all studies that evaluated prucalopride for the treatment of gastroparesis and chronic idiopathic constipation in adults. Prucalopride is an effective and safe option based on all the studies currently conducted. Thus, it may be the first-line treatment in the future. Prucalopride has the potential to be useful in the treatment of functional constipation and other forms of gastrointestinal diseases (eg, gastroparesis). Through the research on this potential, prucalopride is expected to be a useful and versatile option for treating gastrointestinal diseases in the future.

Management of Opioid-Induced and Non-Opioid-Related Constipation in Patients With Cancer: Systematic Review and Meta-Analysis

PROBLEM IDENTIFICATION

A systematic review and meta-analysis was conducted to inform the development of national clinical practice guidelines on the management of cancer constipation.

LITERATURE SEARCH

PubMed®, Wiley Cochrane Library, and CINAHL® were searched for studies published from May 2009 to May 2019.

DATA EVALUATION

Two investigators independently reviewed and extracted data from eligible studies. The Cochrane Collaboration risk-of-bias tool was used, and the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to assess the certainty of the evidence.

SYNTHESIS

For patients with cancer and opioid-induced constipation, moderate benefit was found for osmotic or stimulant laxatives; small benefit was found for methylnaltrexone, naldemedine, and electroacupuncture. For patients with cancer and non-opioid-related constipation, moderate benefit was found for naloxegol, prucalopride, lubiprostone, and linaclotide; trivial benefit was found for acupuncture.

IMPLICATIONS FOR PRACTICE

Effective strategies for managing opioid-induced and non-opioid-related constipation in patients with cancer include lifestyle, pharmacologic, and complementary approaches.

SUPPLEMENTAL MATERIAL CAN BE FOUND AT&NBSP;HTTPS

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ONS Guidelines™ for Opioid-Induced and Non-Opioid-Related Cancer Constipation

PURPOSE

This evidence-based guideline intends to support clinicians, patients, and others in decisions regarding the treatment of constipation in patients with cancer.

METHODOLOGIC APPROACH

An interprofessional panel of healthcare professionals with patient representation prioritized clinical questions and patient outcomes for the management of cancer-related constipation. Systematic reviews of the literature were conducted. The GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was used to assess the evidence and make recommendations.

FINDINGS

The panel agreed on 13 recommendations for the management of opioid-induced and non-opioid-related constipation in patients with cancer.

IMPLICATIONS FOR NURSING

The panel conditionally recommended a bowel regimen in addition to lifestyle education as first-line treatment for constipation. For patients starting opioids, the panel suggests a bowel regimen as prophylaxis. Pharmaceutical interventions are available and recommended if a bowel regimen has failed. Acupuncture and electroacupuncture for non-opioid-related constipation are recommended in the context of a clinical trial.

SUPPLEMENTARY MATERIAL CAN BE FOUND AT&NBSP;HTTPS

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Systematic review with meta-analysis: efficacy and safety of treatments for opioid-induced constipation

BACKGROUND

When opioid-induced constipation is treated with centrally acting opioid antagonists, there may be opioid withdrawal or aggravation of pain due to inhibition of μ-opioid analgesia. This led to the development of peripherally acting μ-opioid receptor antagonists (PAMORAs).

AIM

To evaluate the efficacy of available PAMORAs and other approved or experimental treatments for relieving constipation in patients with opioid-induced constipation, based on a systematic review and meta-analysis of published studies.

METHODS

A search of MEDLINE, EMBASE and EBM Reviews Cochrane Central Register of Controlled Trials was completed in July 2019 for randomised trials compared to placebo. FDA approved doses or highest studied dose was evaluated. Efficacy was based on diverse endpoints, including continuous variables (the bowel function index, number of spontaneous bowel movements and stool consistency based on Bristol Stool Form Scale), or responder analysis (combination of >3 spontaneous bowel movements or complete spontaneous bowel movements plus 1 spontaneous bowel movement or complete spontaneous bowel movements, respectively, over baseline [so-called FDA endpoints]). Adverse effects evaluated included central opioid withdrawal, serious adverse events, abdominal pain and diarrhoea.

RESULTS

We included 35 trials at low risk of bias enrolling 13 566 patients. All PAMORAs demonstrated efficacy on diverse patient response endpoints. There was greater efficacy with approved doses of the PAMORAs (methylnaltrexone, naloxegol and naldemidine), with lower efficacy or lower efficacy and greater adverse effects with combination oxycodone with naloxone, lubiprostone and linaclotide.

CONCLUSIONS

Therapeutic response in opioid-induced constipation is best achieved with the PAMORAs, methylnaltrexone, naloxegol and naldemidine, which are associated with low risk of serious adverse events.

An approach to the diagnosis and management of Rome IV functional disorders of chronic constipation

Introduction: Chronic constipation is highly prevalent, affecting between 10% and 15% of the population. The Rome IV criteria categorizes disorders of chronic constipation into four subtypes: (a) functional constipation, (b) irritable bowel syndrome with constipation, (c) opioid-induced constipation, and (d) functional defecation disorders, including inadequate defecatory propulsion and dyssynergic defecation. The initial management approach for these disorders is similar, focusing on diet, lifestyle and the use of standard over-the-counter laxatives. If unsuccessful, further therapy is tailored according to subtype.Areas covered: This review covers the definition, epidemiology, diagnostic criteria, investigations and management of the Rome IV disorders of chronic constipation.Expert opinion: By adopting a logical step-wise approach toward the diagnosis of chronic constipation and its individual subtypes, clinicians have the opportunity to tailor therapy accordingly and improve symptoms, quality of life, and patient satisfaction.

Implications of the Opioid Epidemic for the Clinical Gastroenterology Practice

PURPOSE OF REVIEW

The opioid epidemic in the USA has led to a rise in opioid-related gastrointestinal (GI) side effects that are often difficult to diagnose and treat. The aim of this report is to discuss opioid pathophysiology, opioid-related GI side effects, clinical presentation, and diagnostic criteria and to review the current pharmacotherapy available.

RECENT FINDINGS

Opioid-related GI disorders are increasingly recognized and include, but are not limited to, opioid-induced esophageal dysfunction (OIED), gastroparesis, opioid-induced constipation (OIC), narcotic bowel syndrome (NBS), acute post-operative ileus, and anal sphincter dysfunction. Treatment of these conditions is challenging. OIC has the most available pharmacotherapy for treatment, including classical laxatives, peripherally acting μ-receptor antagonists (PAMORAs), novel therapies (lubiprostone, prucalopride- 5-HT agonist), and preventative therapies (PR oxycodone/naloxone). The gastrointestinal effects of opioid therapy are variable and often debilitating. While medical management for some opioid-related GI side effects exists, limiting or completely avoiding opioid use for chronic non-cancer pain will mitigate these effects most effectively.

Use of prucalopride in adults with chronic idiopathic constipation

Introduction: Prucalopride is a selective 5-HT₄ receptor agonist with colonic prokinetic activity. It was recently approved by the FDA for the treatment of chronic idiopathic constipation. Before this approval, there were limited options to improve colonic motility in the treatment of chronic idiopathic constipation. Areas covered: We systematically searched PubMed, Embase, ClinicalTrials.gov, and international conference presentations, and we reviewed all studies that evaluated prucalopride for the treatment of chronic idiopathic constipation in adults. In this review, we discuss the pharmacokinetics, pharmacodynamics, receptor interactions, phase I-IV clinical trials, and safety outcomes of prucalopride in adults, including the elderly. Expert opinion: Prucalopride is an effective agent to improve colonic motility, decrease colonic transit time, and increase complete spontaneous bowel movements in patients with chronic idiopathic constipation. Unlike previously available 5-HT₄ receptor agonists such as cisapride and tegaserod, prucalopride does not interact with the cardiac hERG potassium channels or other serotonergic receptors in blood vessels and is not associated with an increase in major adverse cardiovascular events. Additionally, prucalopride has demonstrated promise in the treatment of gastroparesis, post-operative ileus, and opioid-induced constipation. Prucalopride directly stimulates colonic motility, differentiating it from all other medications (exclusively osmotic or chloride secretagogues) approved for chronic constipation in the last decade.

Clinical Efficacy and Safety Profile of Prucalopride in Chronic Idiopathic Constipation

Chronic idiopathic constipation (CIC) can be defined as bowel movements that are difficult to pass, are not occurring frequently, or have incomplete evacuation during defecation. A high-fiber diet and laxatives are the commonly used treatments, but in many cases, they do not produce satisfactory results. The first line of treatment is osmotic laxatives. If there is no improvement, the second line is guanylate cyclase-C (GCC) agonists like linaclotide or prokinetic agents such as prucalopride. On December 14, 2018, the United States Food and Drug Administration (US FDA) approved prucalopride for treating chronic idiopathic constipation. Prucalopride is a prokinetic agent which works at the 5-hydroxytryptamine receptor 4 (5-HT4) as an agonist with greater receptor selectivity. Patients on prucalopride reported improved symptoms, quality of life and satisfaction. The most frequent adverse events were headaches and problems related to the gastrointestinal tract. Caution should be taken when using prucalopride in patients with impaired liver and renal function. In Canada, prucalopride has been approved for treatment of female patients with chronic idiopathic constipation who have failed therapy with at least two laxatives from different classes over a six-month period.

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.

Prucalopride for the treatment of constipation: a view from 2015 and beyond

Prucalopride is a prokinetic drug, that has been commercially available in recent years for the treatment of chronically constipated patients. In this update of a previous 2016 article, we reviewed the more recent data supporting its role in the treatment of constipation and constipation-associated conditions. Areas covered: We carried out an extensive literature review on the effects of prucalopride for the years 2012-2018 by means of scientific databases and manual research. More evidence was found on its possible therapeutic role in conditions in which constipation plays a role as an associated symptom, such as opioid-induced constipation, constipation-predominant irritable bowel syndrome, post-operative ileus, colonic diverticular disease, drug-related constipation, and chronic intestinal pseudo-obstruction. Expert opinion: Based on the added literature evidence, we feel that prucalopride is an effective, although expensive, drug for the treatment of primary and secondary forms of constipation, and of other clinical conditions associated with constipation.

Efficacy of pharmacological therapies for the treatment of opioid-induced constipation: systematic review and network meta-analysis

OBJECTIVE

Opioids are increasingly prescribed in the West and have deleterious GI consequences. Pharmacological therapies to treat opioid-induced constipation (OIC) are available, but their relative efficacy is unclear. We performed a systematic review and network meta-analysis to address this deficit in current knowledge.

DESIGN

We searched MEDLINE, EMBASE, EMBASE Classic and the Cochrane central register of controlled trials through to December 2017 to identify randomised controlled trials (RCTs) of pharmacological therapies in the treatment of adults with OIC. Trials had to report a dichotomous assessment of overall response to therapy, and data were pooled using a random effects model. Efficacy and safety of pharmacological therapies was reported as a pooled relative risk (RR) with 95% CIs to summarise the effect of each comparison tested and ranked treatments according to their P-score.

RESULTS

Twenty-seven eligible RCTs of pharmacological therapies, containing 9149 patients, were identified. In our primary analysis, using failure to achieve an average of ≥3 bowel movements (BMs) per week with an increase of ≥1 BM per week over baseline or an average of ≥3 BMs per week, to define non-response, the network meta-analysis ranked naloxone first in terms of efficacy (RR=0.65; 95% CI 0.52 to 0.80, P-score=0.84), and it was also the safest drug. When non-response to therapy was defined using failure to achieve an average of ≥3 BMs per week, with an increase of ≥1 BM per week over baseline, naldemedinewas ranked first (RR=0.66; 95% CI 0.56 to 0.77, P score=0.91) and alvimopan second (RR=0.74; 95% CI 0.57 to 0.94, P-score=0.71).

CONCLUSION

In network meta-analysis, naloxone and naldemedine appear to be the most efficacious treatments for OIC. Naloxone was the safest of these agents.

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.

Clinical Overview and Considerations for the Management of Opioid-induced Constipation in Patients With Chronic Noncancer Pain

OBJECTIVES

Opioid analgesics may be associated with chronic adverse effects, such as opioid-induced constipation (OIC). Available and emerging prescription medications for OIC in patients with chronic noncancer pain are described, including concerns and challenges associated with OIC management.

METHODS

Narrative review.

RESULTS

OIC is characterized by a change in bowel habits and defecation patterns that occurs when initiating opioid therapy and is associated with reduced bowel frequency, straining, sensation of incomplete evacuation, and/or patient distress related to bowel habits. Prescription medications are indicated when OIC persists despite conservative approaches (eg, increased fiber and fluid intake, exercise, over-the-counter laxatives and stool softeners). Phase 3 studies have demonstrated the efficacy of peripherally acting µ-opioid receptor antagonists (PAMORA; methylnaltrexone, naloxegol, naldemedine), and a chloride channel activator (lubiprostone) for improving OIC in patients with chronic noncancer pain. Although head-to-head studies are lacking, a meta-analysis demonstrated that μ-opioid receptor antagonists were more effective than placebo for the treatment of OIC. The most common adverse effects associated with prescription medications for OIC are gastrointestinal related (eg, nausea, diarrhea, abdominal pain, or distention), with most being mild or moderate in severity. Therapy currently in development for OIC includes the PAMORA axelopran.

DISCUSSION

Health care providers should be aware of this complication in patients receiving opioids and should monitor and address constipation-related symptoms to optimize pain management and improve patient quality of life.

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.

Pharmacological Treatment of Opioid-Induced Constipation Is Effective but Choice of Endpoints Affects the Therapeutic Gain

BACKGROUND

Widespread opioid use has led to increase in opioid-related adverse effects like constipation. We examined the impact of study endpoints on reported treatment benefits.

METHODS

Using MEDLINE, EMBASE, and ClinicalTrials.gov, we searched for randomized control trials targeting chronic opioid-induced constipation (OIC) and subjected them to meta-analysis. Data are given with 95% confidence intervals.

RESULTS

Thirty trials met our inclusion criteria. Combining all dichotomous definitions of responders, active drugs were consistently more effective than placebo, with an odds ratio (OR): 2.30 [2.01-2.63; 15 studies], independent of the underlying drug mechanism. The choice of endpoints significantly affected the therapeutic gain. When time from drug administration to defecation was used, the OR decreased from 4.74 [2.71-4.74] at 6 h or less to 2.46 [1.80-3.30] at 24 h (P < 0.05). Using other response definitions, the relative benefit over placebo was 2.10 [1.77-2.50; 12 studies] for weekly bowel frequency, 2.03 [1.39-2.95; 9 studies] for symptom scores, 2.21 [1.25-3.90; 4 studies] for global assessment scales, and 1.27 [0.79-2.03; 7 studies] for rescue laxative use.

CONCLUSION

While treatment of OIC with active drugs is more effective than placebo, the relative gain depends on the choice of endpoints. The commonly used time-dependent response definition is associated with the highest response rate but is of questionable relevance in a chronic disorder. The limited data do not clearly demonstrate a unique advantage of the peripherally restricted opioid antagonists, suggesting that treatment with often cheaper agents should be optimized before shifting to these novel expensive agents.

Recent advances in understanding and managing chronic constipation

Constipation, a condition characterized by heterogeneous symptoms, is common in Western society. It is associated with reduced physical health, mental health, and social functioning. Because constipation is rarely due to a life-threatening disease (for example, colon cancer), current guidelines recommend empiric therapy. Limited surveys suggest that fewer than half of treated individuals are satisfied with treatment, perhaps because the efficacy of drugs is limited, they are associated with undesirable side effects, or they may not target the underlying pathophysiology. For example, although a substantial proportion of constipated patients have a defecatory disorder that is more appropriately treated with pelvic floor biofeedback therapy than with laxatives, virtually no pharmacological trials formally assessed for anorectal dysfunction. Recent advances in investigational tools have improved our understanding of the physiology and pathophysiology of colonic and defecatory functions. In particular, colonic and anorectal high-resolution manometry are now available. High-resolution anorectal manometry, which is increasingly used in clinical practice, at least in the United States, provides a refined assessment of anorectal pressures and may uncover structural abnormalities. Advances in our understanding of colonic molecular physiology have led to the development of new therapeutic agents (such as secretagogues, pro-kinetics, inhibitors of bile acid transporters and ion exchangers). However, because clinical trials compare these newer agents with placebo, their efficacy relative to traditional laxatives is unknown. This article reviews these physiologic, diagnostic, and therapeutic advances and focuses particularly on newer therapeutic agents.

Efficacy of Treatments for Opioid-Induced Constipation: Systematic Review and Meta-analysis

BACKGROUND & AIMS

Opioid-induced constipation (OIC) is a common problem in patients on chronic opioid therapy for cancer-related and non-cancer-related pain. Approved treatments for OIC are methylnaltrexone, naloxone, naloxegol, alvimopan, naldemedine, and lubiprostone. Since a meta-analysis performed in 2014, 2 new agents have been approved by the Food and Drug Administration for treatment of OIC (naloxegol and naldemedine).

METHODS

We conducted a search of the medical literature following the protocol outlined in the Cochrane Handbook for systematic review. We searched MEDLINE, EMBASE, EMBASE Classic, Web of Science, and the Cochrane Central Register of Controlled Trials until March 2017 to identify randomized controlled trials of peripheral μ-opioid-receptor antagonists (methylnaltrexone, naloxone, naloxegol, alvimopan, axelopran, or naldemedine), lubiprostone, or prucalopride. Response to therapy was extracted in a dichotomous assessment as an overall response to therapy. The effect of pharmacologic therapies was pooled and reported as a relative risk (RR) of failure to respond to the treatment drug, with 95% CIs.

RESULTS

We included 27 placebo-controlled trials in our meta-analysis (23 trials evaluated μ-opioid-receptor antagonists, 3 trials evaluated lubiprostone, and 1 trial evaluated prucalopride). In these trials, 5390 patients received a drug and 3491 received a placebo. Overall, μ-opioid-receptor antagonists, lubiprostone, and prucalopride were superior to placebo for the treatment of OIC, with a RR of failure to respond to therapy of 0.70 (95% CI, 0.64-0.75) and an overall number needed to treat of 5 (95% CI, 4-7). When restricted to only Food and Drug Administration-approved medications for OIC, the RR of failure to respond to therapy was 0.69 (95% CI, 0.62-0.77), with a number needed to treat of 5 (95% CI, 4-7). Sensitivity analyses and meta-regression performed to account for heterogeneity showed that treatment was more likely to be effective in study populations taking higher doses of opiates at baseline or refractory to laxatives. Study duration and prespecified primary outcome did not affect the RR of failure. Participants who received μ-opioid-receptor antagonists were significantly more likely to have diarrhea, abdominal pain, nausea, or vomiting than patients who received placebo.

CONCLUSIONS

In a systematic review and meta-analysis, we found μ-opioid-receptor antagonists to be safe and effective for the treatment of OIC. Prescription-strength laxatives (prucalopride, lubiprostone) are slightly better than placebo in reducing OIC.

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.

Reduction in pain: Is it worth the gain? The effect of opioids on the GI tract

The use of opioid medications for acute and chronic pain has increased significantly in the past 20 years in the United States. Given the high density of opioid receptors in the gastrointestinal tract, side effects are common in these patients including constipation, dysphagia, bloating, nausea, and vomiting. These side effects, which are experienced by most patients who take opioids, can lead to significant impairment in quality of life. Unlike other side effects from opioids, gastrointestinal side effects do not diminish with continued use, often leading patients to reduce or discontinue their opioid treatment to relieve these side effects. Therefore, physicians must be aware and anticipate potential side effects in patients receiving opioids to ensure appropriate pain management.

Opioid misuse in gastroenterology and non-opioid management of abdominal pain

Opioids were one of the earliest classes of medications used for pain across a variety of conditions, but morbidity and mortality have been increasingly associated with their chronic use. Despite these negative consequences, chronic opioid use is increasing worldwide, with the USA and Canada having the highest rates. Chronic opioid use for noncancer pain can have particularly negative effects in the gastrointestinal and central nervous systems, including opioid-induced constipation, narcotic bowel syndrome, worsening psychopathology and addiction. This Review summarizes the evidence of opioid misuse in gastroenterology, including the lack of evidence of a benefit from these drugs, as well as the risk of harm and negative consequences of opioid use relative to the brain-gut axis. Guidelines for opioid management and alternative pharmacological and nonpharmacological strategies for pain management in patients with gastrointestinal disorders are also discussed. As chronic pain is complex and involves emotional and social factors, a multimodal approach targeting both pain intensity and quality of life is best.

Drugs for Treating Opioid-Induced Constipation: A Mixed Treatment Comparison Network Meta-analysis of Randomized Controlled Clinical Trials

CONTEXT

Opioid-induced constipation is a common problem associated with chronic use of opioid analgesics.

OBJECTIVES

The objective of this study was to compare available interventions for the treatment of opioid-induced constipation, using principles of network meta-analysis.

METHODS

Electronic databases were searched for randomized controlled clinical trials evaluating drugs used in opioid-induced constipation. Number of patients with rescue-free bowel movements (RFBM) was the primary outcome, and time for achieving RFBM, adverse events, and changes in the analgesic activity of the opioid analgesics were the secondary outcomes. Inverse variance heterogeneity model was used for direct and mixed treatment comparison analysis. Odds ratio for categorical outcomes and weighted mean difference for numerical outcomes were the effect estimates.

RESULTS

We included a total of 23 studies in the systematic review and 21 in the network meta-analysis. Lubriprostone, prucalopride, naldemedine, naloxegol, alvimopan, subcutaneous, and oral methyl naltrexone were observed to perform better than placebo in terms of RFBM. Additionally, subcutaneous methyl naltrexone was significantly better than lubiprostone, naloxegol, oral methyl naltrexone, and prucalopride. Lubiprostone and naldemedine were associated with increased risks of adverse events. Subcutaneous methyl naltrexone did not significantly affect the analgesia due to background opioid use. Quality of evidence for the comparisons is either low or very low.

CONCLUSION

Subcutaneous methyl naltrexone was found to perform better than other interventions for managing opioid-induced constipation.

The PAC-SYM questionnaire for chronic constipation: defining the minimal important difference

BACKGROUND

The Patient Assessment of Constipation-Symptoms (PAC-SYM) questionnaire is frequently used in clinical trials of constipation. However, the threshold for reduction in total PAC-SYM score used to define a clinical response on this 0-4 point scale has not undergone formal appraisal, and its relationship with clinical benefit as perceived by patients has not been defined.

AIM

To determine the minimal important difference in PAC-SYM score, and the optimum cut-off value for defining responders.

METHODS

The minimal important difference was estimated using data from six international phase 3/4, double-blind, randomised controlled trials of prucalopride in patients with chronic constipation (NCT01147926, NCT01424228, NCT01116206, NCT00485940, NCT00483886, NCT00488137), with anchor- and distribution-based approaches. Five appropriate patient-reported outcomes were selected as anchors. In addition, receiver operating characteristics (ROC) curve analyses were used to investigate responder discrimination for each anchor.

RESULTS

Data from 2884 patients were included. Minimal important difference estimates ranged from -0.52 to -0.63 across the five anchors. Estimates were not affected by study location but were consistently lower for rectal symptoms than for abdominal and stool symptoms. Distribution-based estimates were considerably lower than anchor-based estimates. ROC curve analyses showed optimum cut-off scores for discriminating responders to be similar to anchor-based minimal important difference estimates.

CONCLUSIONS

Anchor-based methods gave consistent results for the minimal important difference, at approximately -0.6, and this value was close to the ROC-determined optimal cut-off scores for responder discrimination. This value could be considered in clinical practice. A slightly more conservative threshold (eg -0.75) could be used in clinical trials to reduce the placebo response rate.

An update on prucalopride in the treatment of chronic constipation

Chronic constipation (CC) is a highly prevalent and often under-appreciated gastrointestinal disorder associated with significant impairment in quality of life. Symptoms of constipation are typically present for a number of years prior to a patient seeking help. Lifestyle modifications followed by, or coupled with, over-the-counter laxatives represent the initial treatment option; however, relief for many is limited and dissatisfaction rates for these approaches remain high. Over recent years, therefore, considerable effort has been exerted on the development of novel pharmacological approaches. Two major targets have emerged, motility and secretion. Research on the former led to the development of a number of prokinetic agents capable of stimulating colonic motility and, thus, accelerating colonic transit. Of these, earlier prototypes such as cisapride and tegaserod, though effective, were ultimately withdrawn due to cardiovascular adverse events due in part to receptor non-selectivity. Highly selective serotonergic receptor agonists have since emerged which appear to be equally effective in stimulating gut motility but are devoid of cardiac side effects. One such agent is prucalopride, which has now been approved for the management of chronic idiopathic constipation in several countries, but not in the United States. Multiple multicenter, randomized placebo-controlled clinical trials have demonstrated superiority for prucalopride compared to placebo in the short to medium term in relieving the major symptoms of constipation in both men and women across a broad spectrum of ages, ethnicities and geographic locations. To date, prucalopride has enjoyed a favorable safety profile and there have been no signals to suggest arrythmogenicity. Efficacy over longer periods of treatment remains to be confirmed. Evidence for efficacy in other forms of constipation, such as opioid-induced constipation and that related to Parkinson's disease is beginning to emerge; its status in the management of constipation-predominant irritable bowel syndrome or foregut motility disorders, such as gastroparesis, remains to be established.

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.

Nanoconjugated NAP as a Potent and Periphery Selective Mu Opioid Receptor Modulator To Treat Opioid-Induced Constipation

Opioids are the mainstay for cancer and noncancer pain management. However, their use is often associated with multiple adverse effects. Among them, the most common and persistent one is probably opioid-induced constipation (OIC). Periphery selective opioid antagonists may alleviate the symptoms of OIC without compromising the analgesic effects of opioids. Recently our laboratories have identified one novel lead compound, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)acetamido]morphinan (NAP), as a peripherally selective mu opioid receptor ligand carrying subnanomolar affinity to the mu opioid receptor and over 100-folds of selectivity over both the delta and kappa opioid receptors, with reasonable oral availability and half-life, and potential to treat OIC. Nanoparticle-based drug delivery systems are now widely considered due to their technological advantages such as good stability, high carrier capacity, low therapeutic side effects, etc. Herein we report nanoparticle supported NAP as a potential candidate for OIC treatment with improved peripheral selectivity over the original lead compound NAP.

Prucalopride succinate for the treatment of constipation: an update

Constipation is a disorder frequently complained about by patients in daily clinical practice. However, to date, its treatment is still commonly unsatisfactory, especially concerning patients' quality of life, when using conventional measures. Prucalopride, a selective 5-hydroxytryptamine receptor 4 agonist, was introduced to the market in 2009 and has been commercially available in Europe since 2010. The main effect of prucalopride is to stimulate colonic motility, which explains its efficacy to treat constipated patients unresponsive to other regimens. Literature search was carried out to look for effects of prucalopride on constipated patients. Several papers were found demonstrating that prucalopride is effective in treatment of constipated patients. Due to its few side effects, the lack of cardiovascular effects and interactions with other drugs, prucalopride may be safely used in elderly people as well.

Translating Clinical Findings into the Patient's Perspective: Post-hoc Pooled Analysis of Bowel Movement Changes as a Predictor of Improvement in Patients' Opioid-induced Constipation Symptoms and Outcomes

PURPOSE

Opioid-induced constipation (OIC) is a bothersome side effect of opioid use for the management of noncancer pain, affecting patients' health-related quality of life and chronic-pain management. The objective of this study was to examine the relationship between changes in the frequency of spontaneous bowel movements (SBMs) and changes in patient-reported outcomes (PROs) among patients with OIC treated with naloxegol.

METHODS

Post hoc analyses were conducted using pooled data from two Phase III 12-week, placebo-controlled trials of naloxegol for the treatment of OIC (NCT01309841 and NCT01323790). Patients completed the Patient Assessment of Constipation-Quality of Life (PAC-QOL) and PAC-Symptoms (PAC-SYM) at each study visit, and the Straining Scale and Bristol Stool Scale (BSS) with each bowel movement for the study duration. Four subgroups were created based on improvements from baseline in mean frequency of SBMs per week: 0 or worse (no change), +1 SBM, +2 SBMs, and +≥3 SBMs. Spearman correlations assessed the association between mean SBM changes from baseline and mean changes from baseline in PROs; analysis of covariance was used to compare changes from baseline.

FINDINGS

A total of 1337 patients with mean (SD) age of 52.2 (11.0) years were included in this analysis. The patient population was predominantly white (79.0%) and female (62.4%). At baseline, mean SBM frequency was 1.4 (1.0) per week. At study end, all 4 SBM-change subgroups experienced improvements in PAC-QOL, PAC-SYM, Straining Scale, and BSS scores, and these changes were significantly correlated with mean changes from baseline in SBMs per week. The subgroup of patients with an increase in SBMs of ≥3 per week experienced the greatest improvements in PROs.

IMPLICATIONS

In these patients with OIC, an improvement in the frequency of SBMs by ≥3 per week was associated with consistent improvements in PROs, providing support for the use of improvements in SBMs as a clinical outcome surrogate for managing patients with OIC. Further research is needed to determine a threshold for change in SBMs that is clinically meaningful in both research and clinical settings. A key limitation was the post hoc nature of the study, which was not powered prospectively to examine these relationships.

Opioids and GI Motility-Friend or Foe?

OPINION STATEMENT

The use of opioids for the treatment of chronic non-cancer pain is growing at an alarming rate. Opioid-induced bowel dysfunction (OBD) is a common adverse effect of long-term opioid treatment manifesting as constipation, nausea, and vomiting. These effects are primarily mediated by peripheral μ-opioid receptors with resultant altered GI motility and function. As a result, patients may present with opioid-induced constipation (OIC), opioid-induced nausea and vomiting (OINV), and/or narcotic bowel syndrome (NBS). This often leads to decreased quality of life and in many cases, discontinuation of opioid therapy. There is limited evidence to support the use of traditional anti-emetics and laxatives in the treatment of OBD. Tapering the dose of opioids, switching to transdermal application, opioid rotation, or dual-action opioids, such as tapentadol, may be helpful in the treatment of OBD. Novel agents, such as peripherally acting μ-opioid receptor antagonists which target the cause of OIC, show promise in the treatment of OBD and should be considered when conventional laxatives fail. This chapter will review the pathophysiology of OBD, including OINV and OIC, and treatment options available.

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.

Pharmacokinetics and tissue distribution study of prucalopride in rats by ultra high performance liquid chromatography with tandem mass spectrometry

A sensitive, reliable and high throughput ultra high performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the determination of prucalopride in rat plasma and various tissues (including heart, liver, spleen, lung, kidney, stomach,small intestine, large intestine, cecum, cerebrum, cerebellum, and ovary). The plasma and tissues samples were treated by protein precipitation with acetonitrile using carbamazepine as an internal standard (IS). Chromatographic separation was performed on a Waters ACQUITY UPLC^® HSS C18 column (2.1mm×50mm, 1.8μm) with a gradient mobile phase consisting of acetonitrile-water (containing 0.1% formic acid) as mobile phase at a flow rate of 0.2mL/min. The quantification was performed by multiple reactions monitoring mode with m/z 367.99→195.89 for prucalopride and m/z 236.97→194.04 for carbamazepine on a Waters Xevo TQD mass spectrometry equipped with electrospray ionization (ESI) source. The calibration curve was linear in the range of 0.1-100ng/mL for plasma and various tissues (r≥0.99) with a lower limit of quantification of 0.1ng/mL. The recoveries obtained for prucalopride were more than 85%. The validated method was successfully applied to the pharmacokinetics and tissue distribution study of prucalopride after oral administration to rats. The pharmacokinetic parameters were demonstrated as followed: the time to reach peak concentration (T_max) was 1.0h, and the peak concentration (C_max) was 21.71±4.28ng/mL, the half-life (t_1/2) was 18.21±0.69h, and the area under the curve (AUC) was 59.30±9.43ngh/mL. Tissue distribution showed the highest level was observed in stomach and intestine, then in liver, which indicated that prucalopride was absorbed firstly in stomach and intestine, and mainly accumulated in liver. It was also the first study to investigate the tissue distribution of prucalopride in rats following oral administration.

Management of chronic constipation in adults

Chronic constipation (CC) is an extremely common condition with an estimated prevalence of up to 24%. Most patients with CC should be treated in primary care. Changes in lifestyle, including increased intake of dietary fibre, fluid, and exercise, should be attempted in most patients. Osmotic or stimulant laxatives are indicated if there are insufficient effects of lifestyle changes. Prokinetics and secretagogues should be restricted to those not responding to basic treatment. Anorectal physiology tests and assessment of colorectal transit time are indicated if medical treatment fails or if symptoms indicate severely obstructed defecation. If symptoms indicate an underlying structural disorder, barium or magnetic resonance evacuation proctography is indicated. Biofeedback therapy is effective in patients with dyssynergic defecation. In patients with other evacuation disorders, rectally administered laxatives or transanal irrigation should be attempted. Surgery is restricted to the minority of CC patients with very severe symptoms not responding to conservative treatment.

Use of Prucalopride for Chronic Constipation: A Systematic Review and Meta-analysis of Published Randomized, Controlled Trials

This article highlights the role of prucalopride in the management of chronic constipation based upon the principles of meta-analysis using data reported in the published randomized, controlled trials. Sixteen randomized, controlled trials on 3943 patients reported the effectiveness of prucalopride in patients with chronic constipation. Prucalopride successfully increased the frequency of spontaneous bowel movements per week in all variable doses of 1 mg (standardized mean difference [SMD], 0.42 [95% CI, 0.18-0.66; P = 0.006]), 2 mg (SMD, 0.34 [95% CI, 0.11-0.56; P = 0.003]), and 4 mg (SMD, 0.33 [95% CI, 0.22-0.44; P = 0.00001]). The risks of adverse events or side effects such as headache, abdominal cramps, excessive flatulence, dizziness, diarrhea, and rash were higher (odds ratio, 1.70 [95% CI, 1.27 to -2.27; P = 0.0004]) in prucalopride group. Prucalopride is clinically a beneficial pharmacotherapy for chronic constipation and its routine use may be considered in patients with chronic simple laxative-resistant constipation.

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.

The Effect of DA-9701 in Opioid-induced Bowel Dysfunction of Guinea Pig

Background/Aims

Opioid induced bowel dysfunction (OIBD) is associated with decreased gastrointestinal (GI) propulsive activity due to intake of opioid analgesics. DA-9701, a novel prokinetic agent formulated with Pharbitis Semen and Corydalis Tuber has promising effects on GI motor function. Therefore, we aim to evaluate the prokinetic effects of DA-9701 in an OIBD model of guinea pig.

Methods

The ileal and distal colon muscle contraction in presence of different doses of DA-9701, morphine, and combination (morphine + DA-9701) was measured by tissue bath study. The prokinetic effect of DA-9701 was assessed by charcoal transit and fecal pellet output assay in an OIBD model of guinea pig.

Results

DA-9701 significantly increased the amplitude and area under the curve of ileal muscle contraction, while there was insignificant effect on the distal colon compared to the control. The maximal amplitude of ileal muscle contraction was acquired at a concentration of 10 μg/mL of DA-9701. In contrast, morphine significantly decreased the amplitude of ileal and distal colon muscle contraction compared to the control. Morphine delayed both upper (P < 0.01) and lower (P < 0.05) GI transit, and delayed GI transit was restored by the administration of DA-9701. Morphine induced reduction of contractility was significantly ameliorated by addition of DA-9701 in both ileal and distal colon muscles.

Conclusions

DA-9701 significantly increased the amplitude of contraction of the ileal muscle, however the distal colon muscle contraction was insignificant. Additionally, it restored delayed upper and lower GI transit in an OIBD model of guinea pig, and it might prove to be a useful candidate drug in a clinical trial for OIBD.

Persistent constipation and abdominal adverse events with newer treatments for constipation

Background

Clinical trials of several new treatments for opioid-induced constipation (OIC), chronic idiopathic constipation (CIC) and constipation-predominant irritable bowel syndrome (IBS-C) have focused on differences between subjects relieved of constipation with placebo and active treatment. Patients and clinicians however, are more interested in the probability these treatments provide actual relief of constipation and its associated symptoms.

Methods

We searched the medical literature using MEDLINE and Cochrane central register of controlled trials. Randomised, placebo-controlled trials that examined the use of methylnaltrexone, naloxegol, lubiprostone, prucalopride or linaclotide in adults with OIC, CIC and IBS-C were eligible for inclusion. The primary efficacy measure was relief of constipation. Adverse event data for abdominal symptoms were also analysed.

Key results and findings

25 publications were included in our analyses. The proportion of constipated individuals with active treatment was significantly lower than the proportion with placebo; however, in 15 of these 20 trials analysed, a majority of patients remained constipated with active treatment. Analyses of adverse event data revealed that the percentage of participants who experienced abdominal pain, diarrhoea and flatulence with active treatment was higher than that with placebo in the majority of trials analysed.

Conclusions

Newer pharmacological treatments for constipation are superior to placebo in relieving constipation, but many patients receiving active treatment may remain constipated. In addition, all 5 of the treatments studied are accompanied by no change or a possible increase in the prevalence of abdominal symptoms, such as abdominal pain, diarrhoea and flatulence.