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

The Use of Peripheral μ-Opioid Receptor Antagonists (PAMORA) in the Management of Opioid-Induced Constipation: An Update on Their Efficacy and Safety

Peripherally acting μ-opioid receptor antagonists (PAMORAs) constitute a class of drugs which reverse opioid-induced constipation (OIC) with similar opioid analgesic effects. OIC differs from other forms of constipation in that it is an iatrogenic condition that occurs when an opioid acts on the dense network of μ-opioid receptors in the enteric system, which affect a variety of functions including gastrointestinal motility, secretion, and other factors that can cause bowel dysfunction. Unfortunately, laxative products, bowel regimens, dietary changes, and lifestyle modifications have limited effectiveness in preventing OIC, Opioid-associated adverse effect which occurs in 40% to 80% of opioid patients and may led to cessation of the treatment. PAMORAs are μ-receptor opioid antagonists specifically developed so that they have very limited ability to cross the blood-brain barrier and thus they are able to antagonize peripheral but not central μ-opioid receptors. PAMORAs are designed to have no effect on the analgesic benefits of opioid pain relievers but to relieve but antagonizing the effects of the opioid in the gastrointestinal system. The three main PAMORAS are methyltrexone (oral or parenteral), naldemedine (oral only), and naloxegol (oral only). Clinical studies demonstrate the safety and efficacy of these agents for alleviating constipation without diminishing the analgesic effect of opioid therapy. The aim of this narrative review to update the current status of PAMORAs for treating OIC in terms of safety and efficacy.

Peripheral Opioid Receptor Antagonists for Opioid-Induced Constipation: A Primer on Pharmacokinetic Variabilities with a Focus on Drug Interactions

Opioid analgesics remain a treatment option for refractory acute and chronic pain, despite their potential risk for abuse and adverse events (AEs). Opioids are associated with several common AEs, but the most bothersome is opioid-induced constipation (OIC). OIC is often overlooked but has the potential to affect patient quality of life, increase associated symptom burden, and impede long-term opioid compliance. The peripherally acting µ-receptor antagonists (PAMORAs) are a class of drugs that include methylnaltrexone, naloxegol, and naldemedine. Collectively, each is approved for the treatment of OIC. PAMORAs work peripherally in the gastrointestinal tract, without impacting the central analgesic effects of opioids. However, each has unique pharmacokinetic properties that may be impacted by coadministered drugs or food. This review focuses on important metabolic and pharmacokinetic principals that are pertinent to drug interactions involving µ-opioid receptor antagonists prescribed for OIC. It highlights subtle differences among the PAMORAs that may have clinical significance. For example, unlike naloxegol or naldemedine, methylnaltrexone is not a substrate for CYP3A4 or p-glycoprotein; therefore, its plasma concentration is not altered when coadministered with concomitant medications that are CYP3A4 or p-glycoprotein inducers or inhibitors. With a better understanding of pharmacokinetic nuances of each PAMORA, clinicians will be better equipped to identify potential safety and efficacy considerations that may arise when PAMORAs are coadministered with other medications.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Naldemedine: A Review in Opioid-Induced Constipation

Naldemedine [Symproic^® (Japan; USA); Rizmoic^® (EU)], an orally available peripherally acting μ-opioid receptor antagonist (PAMORA), is approved in several countries for the treatment of opioid-induced constipation. In phase III trials, naldemedine was more effective than placebo at increasing the frequency of bowel movements in patients with constipation induced by opioid treatment for cancer pain or chronic non-cancer pain. Naldemedine was also associated with improvements in patient-rated constipation-related symptoms and quality of life. Naldemedine was generally well tolerated, including over the longer term. Because naldemedine specifically targets opioid receptors in the gastrointestinal (GI) tract and does not cross the blood-brain barrier, it does not cause opioid withdrawal symptoms or interfere with centrally mediated opioid analgesia. Consistent with its mechanism of action, the most commonly reported adverse events were GI in nature. In conclusion, current data indicate that naldemedine is an effective and generally well-tolerated treatment option for opioid-induced constipation in patients with cancer pain or chronic non-cancer pain, with the convenience of once-daily oral dosing.

Safety and efficacy of naldemedine in cancer patients with opioid-induced constipation: a pooled, subgroup analysis of two randomised controlled studies

Objective

This post hoc, pooled, subgroup analysis of two randomised studies evaluated baseline characteristics that may influence the efficacy and safety of naldemedine in patients with opioid-induced constipation (OIC) and cancer.

Methods

Data for patients who received 0.2 mg naldemedine or placebo were pooled from randomised, placebo-controlled, phase IIb and phase III studies. Proportions of spontaneous bowel movement (SBM) responders and patients with diarrhoea were assessed for each treatment group. For the patient subgroups with or without possible blood–brain barrier (BBB) disruptions, changes in Numerical Rating Scale (NRS) and Clinical Opioid Withdrawal Scale (COWS) scores were assessed.

Results

A total of 307 patients were included in this analysis (naldemedine: n=155; placebo: n=152). The pooled proportion of SBM responders was 73.5% with naldemedine versus 35.5% with placebo. There was a significant increase in the proportion of SBM responders with naldemedine versus placebo (38.0% (95% CI 27.6% to 48.4%); p<0.0001). Greater proportions of SBM responders and patients who experienced diarrhoea were observed with naldemedine versus placebo in all subgroups. Changes from baseline in NRS and COWS scores were similar with naldemedine or placebo in patients with or without brain metastases.

Conclusions

Although not powered to detect statistically significant differences in treatment effect among subgroups, this study demonstrated that naldemedine appeared to benefit patients with OIC and cancer, irrespective of baseline characteristics, and did not seem to affect analgesia or withdrawal–even in patients with potential BBB disruptions. Baseline characteristics did not appear to affect the incidence of diarrhoea in patients who received naldemedine.

Trial registration numbers

JapicCTI-111510 and JapicCTI-132340.

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.

Pharmacologic effects of naldemedine, a peripherally acting μ-opioid receptor antagonist, in in vitro and in vivo models of opioid-induced constipation

BACKGROUND

Naldemedine (S-297995) is a peripherally acting μ-opioid receptor antagonist developed as a once-daily oral drug for opioid-induced constipation (OIC) in adults with chronic noncancer or cancer pain. This study characterized the pharmacological effects of naldemedine in vitro and in vivo.

METHODS

The binding affinity and antagonist activity of naldemedine against recombinant human μ-, δ-, and κ-opioid receptors were assayed in vitro. Pharmacologic effects of naldemedine were investigated using animal models of morphine-induced inhibition of small and large intestinal transit, castor oil-induced diarrhea, antinociception, and morphine withdrawal.

KEY RESULTS

Naldemedine showed potent binding affinity and antagonist activities for recombinant human μ-, δ-, and κ-opioid receptors. Naldemedine significantly reduced opioid-induced inhibition of small intestinal transit (0.03-10 mg kg^-1 ; P < 0.05) and large intestinal transit (0.3-1 μmol L^-1 ; P < 0.05). Naldemedine (0.03-1 mg kg^-1 ) pretreatment significantly reversed the inhibition of castor oil-induced diarrhea by subcutaneous morphine (P < 0.01). Naldemedine (1-30 mg kg^-1 ) pretreatment (1 or 2 hours) did not alter the analgesic effects of morphine in a model measuring the latency of a rat to flick its tail following thermal stimulation. However, a significant delayed reduction of the analgesic effect of morphine was seen with higher doses of naldemedine (10-30 mg kg^-1 ). Some centrally mediated and peripherally mediated withdrawal signs in morphine-dependent rats were seen with naldemedine doses ≥3 and ≥0.3 mg kg^-1 , respectively.

CONCLUSIONS & INFERENCES

Naldemedine displayed potent binding affinity to, and antagonistic activity against, μ-, δ-, and κ-opioid receptors. Naldemedine tempered OIC in vivo without compromising opioid analgesia.

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

BACKGROUND AND AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Influence of Renal or Hepatic Impairment on the Pharmacokinetics, Safety, and Tolerability of Naldemedine

Naldemedine is a peripherally acting μ‐opioid‐receptor antagonist for the treatment of opioid‐induced constipation. Two phase 1 single‐dose studies investigated the pharmacokinetics and safety of a 0.2‐mg oral dose of naldemedine in subjects with renal impairment (mild, n = 9; moderate, n = 9; severe, n = 6; and end‐stage renal disease, n = 8) or hepatic impairment (mild or moderate, n = 8 each) and demographically matched healthy subjects with normal renal and hepatic function (n = 8, both studies). Pharmacokinetic assessments indicate that dose adjustments for naldemedine are not necessary for subjects with any degree of renal impairment or for subjects with mild or moderate hepatic impairment. In subjects with renal impairment compared with healthy subjects with normal renal function, the geometric mean ratios of naldemedine area under the concentration‐time curve (AUC_0‐inf) ranged from 82.8% (90%CI 69.5% to 98.6%) to 137.8% (90%CI 114.0% to 166.5%). Renal clearance decreased with reduced renal function (normal function 1.3 L/h; mild impairment 1.1 L/h; moderate impairment 1.0 L/h; severe impairment 0.5 L/h), and only 2.7% of naldemedine was removed by hemodialysis. In subjects with hepatic impairment compared with healthy subjects with normal hepatic function, the geometric mean ratio of AUC_0‐inf ranged from 82.8% (90%CI 65.7% to 104.5%) to 105.2% (90%CI 83.4% to 132.6%). Naldemedine was well tolerated in both healthy subjects and subjects with renal or hepatic impairment, and reported adverse events were generally consistent with the known safety profile.

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.

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.

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.

A meta-analysis of naldemedine for the treatment of opioid-induced constipation

INTRODUCTION

Opioid-induced constipation (OIC) is a common adverse effect in patients under long-term opioid therapy. Naldemedine is a novel peripherally acting μ-opioid receptor antagonists being developed for the treatment of OIC without affecting central analgesia. This meta-analysis is to assess the current evidence for efficacy and safety of naldemedine for the treatment of OIC. Areas covered: We searched through MEDLINE, EMBASE, Web of Science and Cochrane Library, 'ISRCTN Register' and'ClinicalTrials.gov' (up to Aug 2018). Our final review included five randomized clinical trials (1751 participants in total), three trials observed naldemedine for the treatment of OIC in non-cancer patients and two trials in cancer patients. A Random Effects model was used for all comparisons. Subgroup analyses for the following subgroups were carried out: naldemedine 0.1 mg; 0.2 mg; 0.4 mg; cancer patients; non-cancer patients. Expert opinion: Naldemedine improved the proportion of responders and spontaneous bowel movements frequency. The incidence of serious adverse effects (AEs) in naldemedine group was higher than placebo, especially in cancer patient subgroup. The AEs occurred in participants with naldemedine were mild to moderate and well tolerated during treatment. The results of this network meta-analysis will guide the future researchers in evaluating naldemedine for the treatment of OIC.

Naldemedine in Japanese patients with opioid-induced constipation and chronic noncancer pain: open-label Phase III studies

Introduction

Naldemedine is a peripherally-acting µ-opioid-receptor antagonist, approved in Japan for opioid-induced constipation (OIC). In two open-label, single-arm, Phase III studies, we evaluated the safety and efficacy of naldemedine in Japanese patients with OIC receiving regular-use opioids (COMPOSE-6) or prolonged-release oxycodone (COMPOSE-7) for chronic noncancer pain.

Methods

Eligible Japanese adults with OIC and chronic noncancer pain received once-daily oral naldemedine 0.2 mg for 48 weeks, irrespective of food intake. Primary end points included measures of treatment-emergent adverse events (TEAEs), pain intensity, and opioid withdrawal. Secondary efficacy end points were evaluated at treatment week 2. Patient Assessment of Constipation Symptoms (PAC-SYM) and Quality of Life (PAC-QOL) scores were evaluated in both 48-week studies.

Results

Of patients enrolled in COMPOSE-6 (N = 43) and COMPOSE-7 (N = 10), TEAEs were reported in 88% (95% CI 74.9–96.1) and 90% (95% CI 55.5–99.7), respectively. The most frequently reported TEAEs, nasopharyngitis and diarrhea, were mostly mild or moderate in severity. Assessments of pain intensity and opioid withdrawal remained stable over the 48-week treatment periods of both studies. The proportion of spontaneous bowel-movement responders at week 2 in COMPOSE-6 was 81.0% (95% CI 65.9–91.4) and 90.0% (95% CI 55.5–99.7) in COMPOSE-7. Significant and sustained improvements in PAC-SYM and PAC-QOL scores were also observed in both studies (all P<0.05).

Conclusion

Side effects that occurred with naldemedine were mostly mild or moderate in severity, and the data suggested that naldemedine can improve bowel function and QOL in Japanese patients with OIC receiving regular-use opioids or prolonged-release oxycodone for chronic noncancer pain.

Peripherally Acting μ-Opioid Receptor Antagonists for the Treatment of Opioid-Related Side Effects: Mechanism of Action and Clinical Implications

Opioid receptors are distributed throughout the central and peripheral nervous systems and on many nonneuronal cells. Therefore, opioid administration induces effects beyond analgesia. In the enteric nervous system (ENS), stimulation of µ-opioid receptors triggers several inhibitory responses that can culminate in opioid-induced bowel dysfunction (OBD) and its most common side effect, opioid-induced constipation (OIC). OIC negatively affects patients' quality of life (QOL), ability to work, and pain management. Although laxatives are a common first-line OIC therapy, most have limited efficacy and do not directly antagonize opioid effects on the ENS. Peripherally acting µ-opioid receptor antagonists (PAMORAs) with limited ability to cross the blood-brain barrier have been developed. The PAMORAs approved by the U S Food and Drug Administration for OIC are subcutaneous and oral methylnaltrexone, oral naloxegol, and oral naldemedine. Although questions of cost-effectiveness and relative efficacy versus laxatives remain, PAMORAs can mitigate OIC and improve patient QOL. PAMORAS may also have applications beyond OIC, including reducing the increased cardiac risk or potential tumorigenic effects of opioids. This review discusses the burden of OIC and OBD, reviews the mechanism of action of new OIC therapies, and highlights other potential opioid-related side effects mediated by peripheral opioid receptors in the context of new OIC therapies.

Population Pharmacokinetics and Exposure-Response Relationships of Naldemedine

Purpose

To characterize population pharmacokinetic (PK) of naldemedine, to identify factors which influence naldemedine PK, and to evaluate their clinical relevancy based on exposure-response relationships.

Methods

A population PK model was developed with pooled naldemedine concentrations from healthy subjects, patients with chronic non-cancer pain and opioid-induced constipation (OIC), and cancer patients with OIC. Exposure-response analyses were performed with efficacy (responder or non-responder) and safety (occurrence of gastrointestinal disorders or not) data in phase 2b and phase 3 studies.

Results

Naldemedine plasma concentrations were adequately described by a 2-compartment model with first-order absorption and absorption lag time. The final model included the effects of age, creatinine clearance, race, and gender on apparent total clearance; the effects of body weight, health status, and food condition on apparent volume of central compartment; and the effect of age on first-order rate of absorption. When subjects took 0.2 mg of naldemedine once daily, the probability of spontaneous bowel movement (SBM) responders was predicted to be approximately 50%, while that of severe gastrointestinal disorders was predicted to be less than 3%. The influence of the covariates on PK was not considered clinically significant because similar efficacy and safety were expected based on the exposure-response analysis.

Conclusions

The covariates are identified in the population PK analysis; however, no dose-adjustment is required for them based on the exposure-response analysis.

Electronic supplementary material

The online version of this article (10.1007/s11095-018-2501-7) contains supplementary material, which is available to authorized users.

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.

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

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

Long-term use of naldemedine in the treatment of opioid-induced constipation in patients with chronic noncancer pain: a randomized, double-blind, placebo-controlled phase 3 study

The long-term safety of naldemedine, a peripherally acting µ-opioid receptor antagonist, was evaluated in patients with opioid-induced constipation and chronic noncancer pain in a 52-week, randomized, double-blind, phase 3 study. Eligible adults who could be on a routine laxative regimen were randomized 1:1 to receive once-daily oral naldemedine 0.2 mg (n = 623) or placebo (n = 623). The primary endpoint was summary measures of treatment-emergent adverse events (AEs). Additional endpoints included opioid withdrawal on the Clinical Opiate Withdrawal Scale and the Subjective Opiate Withdrawal Scale, pain intensity on Numeric Rating Scale, frequency of bowel movements, and constipation-related symptoms and quality of life on the Patient Assessment of Constipation Symptoms and Patient Assessment of Constipation Quality of Life scales, respectively. Treatment-emergent AEs (naldemedine, 68.4% vs placebo, 72.1%; difference: -3.6% [95% confidence interval: -8.7 to 1.5]) and treatment-emergent AEs leading to study discontinuation (6.3% vs 5.8%; difference: 0.5% [-2.2 to 3.1)] were reported for similar proportions of patients. Diarrhea was reported more frequently with naldemedine (11.0%) vs placebo (5.3%; difference: 5.6% [2.6-8.6]). There were no meaningful differences between groups in opioid withdrawal or pain intensity. Sustained significant improvements in bowel movement frequency and overall constipation-related symptoms and quality of life were observed with naldemedine (P ≤ 0.0001 vs placebo at all time points). Naldemedine was generally well tolerated for 52 weeks and did not interfere with opioid-mediated analgesia or precipitate opioid withdrawal. Naldemedine significantly increased bowel movement frequency, improved symptomatic burden of opioid-induced constipation, and increased patients' quality of life vs placebo.

Medical Therapy of Constipation: Current Standards and Beyond

Chronic constipation is a very common medical problem with relevant impact on the patients' quality of life. Modern definitions recognize constipation as a polysymptomatic disorder, including various aspects of disturbed defecation. Current guidelines recommend a stepwise approach in the management of chronic constipation. Isolated or concomitant evacuation disorders should be identified and may need differential/additional treatment. Baseline measures include lifestyle components and bulking agents. The next step recommends treatment with conventional laxatives. In refractory patients, modern medical therapies, such as the prokinetic prucalopride or the secretagogues linalotide or lubiprostone, may be used effectively. For patients with opioid-induced constipation, the modern concept of peripherally acting µ-opioid antagonists has shown to successfully improve this increasing medical problem and even to potentially increase survival time in terminally ill patients on opioid therapy. Prolonged-released oral naloxone (in fixed combination with oxycodone), oral naloxegol or naldemedine, and subcutaneous methylnaltrexone have all demonstrated good efficacy and tolerability in the treatment of opioid-induced constipation. To adequately apply stepwise treatment algorithms, a simple tool to identify treatment failure may improve patient care.

Cardiovascular Safety of the Selective μ-Opioid Receptor Antagonist Naloxegol: A Novel Therapy for Opioid-Induced Constipation

Background:

Naloxegol is a novel selective, peripherally acting μ-opioid receptor antagonist for treating opioid-induced constipation (OIC) in patients with chronic pain syndromes. We analyzed the cardiovascular (CV) safety of naloxegol based on data from its development program prior to approval by the US Food and Drug Administration in 2015.

Methods:

Comprehensive CV safety analyses were performed in 4 clinical studies of naloxegol (12.5 and/or 25 mg) in patients with noncancer pain and OIC: two 12-week, double-blind, randomized studies; a 12-week, double-blind, extension study; and a 52-week, randomized, open-label study versus usual care. Evaluations of baseline CV risk were obtained from medical histories and clinical findings at the time of study initiation.

Results:

Across the 4 studies (N = 2135), 68% of patients had ≥1 CV risk factor and 41% had a history of CV disease, diabetes, or ≥2 other CV risk factors. There were no increases in blood pressure, heart rate, or the rate-pressure product with naloxegol versus placebo. The rates of major adverse cardiovascular events (MACE) per 100 patient-years of exposure were 1.13 (95% confidence interval [CI], 0.31-2.89) for placebo/usual care and 0.75 (95% CI, 0.24-1.75) for naloxegol. The relative risk of MACE for all doses of naloxegol versus placebo was 0.67 (95% CI, 0.14-3.36).

Conclusion:

These data demonstrate that naloxegol has a CV safety profile comparable to placebo/usual care in patients with OIC. Although the observed number of events was low, the data show no CV signal in patients with OIC treated with naloxegol.

Spotlight on naldemedine in the treatment of opioid-induced constipation in adult patients with chronic noncancer pain: design, development, and place in therapy

Opioid-induced constipation (OIC) is an increasingly prevalent problem in the USA due to the growing use of opioids. A novel class of therapeutics, the peripherally acting μ-opioid receptor antagonists (PAMORAs), has been developed to mitigate the deleterious effects of opioids in the gastrointestinal tract while maintaining central analgesia and minimizing opioid withdrawal. This review aimed to summarize the literature on naldemedine, the third PAMORA to gain US Food and Drug Administration (FDA) approval for the treatment of OIC in adults with chronic noncancer pain-related syndromes. Naldemedine has a chemical structure similar to naltrexone, an opioid receptor antagonist, with chemical modifications that limit its ability to cross the blood-brain barrier. Naldemedine was evaluated in two Phase II and three Phase III clinical trials prior to gaining FDA approval. In two pivotal identical Phase III trials, COMPOSE-I (NCT 01965158) and COMPOSE-II (NCT 01993940), patients receiving naldemedine were significantly more likely to respond when compared with placebo (COMPOSE-I: 47.6 vs 34.6%, P=0.002 and COMPOSE-II: 52.5 vs 33.6%, P<0.0001). The most frequent adverse events were abdominal pain (8%) and diarrhea (7%) - rates similar to the other PAMORAs. Based on the available data, naldemedine appears to be an effective and safe drug for the treatment of OIC in adults with chronic noncancer pain.

The Evolving Role of Long-Term Pharmacotherapy for Opioid-Induced Constipation in Patients Being Treated for Noncancer Pain

Nationally, the prescription of opioids for acute and chronic pain is increasing. As opioid use continues to expand and become of increased concern for health-care practitioners, so do the adverse effects and long-term management of those effects. Opioid-induced constipation (OIC) presents a unique challenge because tolerance does not develop to this particular adverse effect, making chronic pain management a delicate balance between relieving pain and preventing long-term adverse effects such as constipation and dependence. Several agents have been developed for the treatment of OIC in patients with chronic noncancer pain on the basis of short-term studies of 12 weeks or less. However, chronic pain management often extends beyond this 12-week boundary, resulting in health-care professionals questioning the safety and efficacy of continued treatment with OIC agents. This review evaluates available literature on long-term treatment of OIC in patients with chronic noncancer pain with lubiprostone, naloxegol, and methylnaltrexone as well as preliminary results of the recently completed naldemedine long-term trial, COMPOSE-3.

Evidence Based Review of Pharmacotherapy for Opioid-Induced Constipation in Noncancer Pain

OBJECTIVE

To summarize and evaluate the existing literature regarding medications to treat opioid-induced constipation (OIC) in patients with chronic noncancer pain (CNCP).

DATA SOURCES

PubMed, EMBASE, and Web of Science were searched using the following terms: constipation, opioid, chronic, pain, noncancer, nonmalignant, methylnaltrexone, alvimopan, lubiprostone, naloxegol, and naldemedine.

STUDY SELECTION AND DATA EXTRACTION

The search was limited to randomized controlled trials reporting human outcomes. Data extracted included the following: study design, population, intervention, control, outcomes related to OIC and safety, and potential biases assessed using Cochrane Collaboration's Risk of Bias Assessment Tool.

DATA SYNTHESIS

After assessment, 16 of the 190 studies were included: methylnaltrexone (n = 4), naloxegol (n = 3), naldemedine (n = 2), lubiprostone (n = 3), and alvimopan (n = 4). Lubiprostone was the only nonperipherally acting µ-opioid receptor antagonist included. Only 1 study (naloxegol) used "usual care" (nonstudy laxative) rather than placebo as a comparator. Placebo-controlled trials demonstrated benefit for methylnaltrexone, naloxegol, naldemedine, and lubiprostone, with conflicting evidence for alvimopan. No data suggest that one agent is better than another. Overall risk of bias across all studies was low to moderate.

CONCLUSIONS

With risk of bias determined to be low to moderate, published data to date suggest that methylnaltrexone, naloxegol, and naldemedine may be appropriate to treat OIC in patients with CNCP.

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.