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

Hailey-Hailey disease successfully treated with naloxone: 2 case reports and Review of the literature on efficacy of opioid receptor antagonist in Hailey-Hailey disease patients

BACKGROUND

Hailey-Hailey disease (HHD), a genetic blistering disease, is caused by a mutation in a calcium transporter protein in the Golgi apparatus encoded by the ATP2C1 gene. Clinically, HHD is characterized by flaccid vesicles, blisters, erosions, fissures, and maceration mainly in intertriginous regions. Some patients remain refractory to conventional treatments. Previously, a series of reports have confirmed naltrexone as an effective option for those patients. However, in China, naltrexone is unavailable in some hospitals and unaffordable for some patients.

OBJECTIVE

To confirm naloxone as a treatment option for HHD, and assess the efficacy rate and safety of naltrexone for patients with HHD.

METHODS

Two patients with biopsy-proven HHD received naloxone (2 mg/d, via intravenous infusion). We followed up with the two patients, assessing the change of skin lesions and obtaining photographs. We searched the PubMed databases using the keywords 'Hailey-Hailey disease' or 'benign familial pemphigus', and 'naltrexone' or 'naloxone', and reviewed English publications of reports and analyzed the efficacy and safety of naltrexone.

RESULTS

Two patients prescribed naloxone showed completely remission in two weeks without any adverse reactions. The total remission rate of naltrexone for HHD is approximately 80%, without severe adverse effects.

CONCLUSION

Naltrexone is effective and safe in the treatment of HHD. Naloxone, an analog of naltrexone, can also effectively and safely treat HHD, potentially offering a new therapeutic option for patients with refractory HHD.

Peripheral opioid receptor antagonism alleviates fentanyl-induced cardiorespiratory depression and is devoid of aversive behavior

Millions of Americans suffering from Opioid Use Disorders face a high risk of fatal overdose due to opioid-induced respiratory depression (OIRD). Fentanyl, a powerful synthetic opioid, is a major contributor to the rising rates of overdose deaths. Reversing fentanyl overdoses has proved challenging due to its high potency and the rapid onset of OIRD. We assessed the contributions of central and peripheral mu opioid receptors (MORs) in mediating fentanyl-induced physiological responses. The peripherally restricted MOR antagonist naloxone methiodide (NLXM) both prevented and reversed OIRD to a degree comparable to that of naloxone (NLX), indicating substantial involvement of peripheral MORs to OIRD. Interestingly, NLXM-mediated OIRD reversal did not produce aversive behaviors observed after NLX. We show that neurons in the nucleus of the solitary tract (nTS), the first central synapse of peripheral afferents, exhibit a biphasic activity profile following fentanyl exposure. NLXM pretreatment attenuates this activity, suggesting that these responses are mediated by peripheral MORs. Together, these findings establish a critical role for peripheral MORs, including ascending inputs to the nTS, as sites of dysfunction during OIRD. Furthermore, selective peripheral MOR antagonism could be a promising therapeutic strategy for managing OIRD by sparing CNS-driven acute opioid-associated withdrawal and aversion observed after NLX.

Naloxegol for the Treatment of Opioid-Induced Constipation in Patients with Cancer Pain: A Pooled Analysis of Real-World Data

OBJECTIVE

The aim of the NALOPOOL project was to assess the efficacy and safety of naloxegol in patients with cancer pain who exhibited opioid-induced constipation (OIC) and were treated under real-world conditions.

METHODS

We pooled individual patient data from three multicenter observational studies conducted with naloxegol in patients with cancer who exhibited OIC and were prescribed naloxegol under real-world conditions. Efficacy outcomes were evaluated after 4 weeks of treatment. All analyses were performed via a visit-wise approach. Heterogeneity was assessed via Cochran's Q-test or Levene's test.

RESULTS

Spontaneous bowel movements (SBM) response (≥3 SBM per week and an increase of ≥1 from baseline; three studies) was reported in 223 of 314 evaluable patients (71%, 95% CI 66-76); clinically relevant improvement in the Patient Assessment of Constipation Quality-of-Life Questionnaire (>0.5 points; three studies) occurred in 179 of 299 evaluable patients (60%, 95% CI 56-74) and in the Patient Assessment of Constipation Symptoms (>0.5 points; two studies) was reported in 131 of 190 evaluable patients (69%, 95% CI 62-76); and clinically relevant improvement in the Bowel Function Index (score ≥ 12 points at the endpoint; two studies;) was reported in 133 of 195 evaluable patients (68%, 95% CI 62-75). No significant heterogeneity was found for any efficacy outcome. The pooled proportion of patients who discontinued the drug owing to adverse reactions was 6.1% (95% CI 3.8% to 8.4%).

CONCLUSIONS

Our results support the use of naloxegol for the management of OIC in patients with cancer pain who do not respond to laxative treatment.

Safety of Naldemedine for Opioid-Induced Constipation - A Systematic Review and Meta-Analysis

Naldemedine is a peripheral acting µ-opioid receptor antagonist approved by the Food and Drug Administration to treat opioid-induced constipation. Concerns about side effects like opioid withdrawal prevent its widespread use, especially for cancer patients. We performed this systematic review and meta-analysis to evaluate existing safety data of naldemedine treating opioid-induced constipation following the PRISMA guidelines. We searched PubMed and the Cochrane Library on April 16th 2024 to identify studies evaluating naldemedine treatment among patients with opioid-induced constipation. Our analysis found no differences between groups comparing naldemedine therapy with placebo-control for treatment-emergent adverse events (OR = 1.06; 95%-CI: 0.91-1.24), serious adverse events (OR = 1.02; 95%-CI: 0.76-1.38). We found no increased risk for opioid withdrawal, while an increased risk for gastrointestinal disorders (OR = 2.08; 95%-CI: 1.72-2.51), particularly higher incidences of diarrhea (OR = 2.44; 95%-CI: 1.81-3.29) and abdominal pain (OR = 3.31; 95%-CI: 2.16-5.06) were found. In the cancer subgroup, treatment-emergent and serious adverse events were more frequent. However, no increased risk for opioid withdrawal was observed. This analysis confirms naldemedine's overall safety in treating opioid-induced constipation, with manageable gastrointestinal side effects. However, the higher adverse events in cancer patients require further investigation to ensure safe use in this population.

Post-marketing safety assessment of constipation drugs: a real-world pharmacovigilance study based on FAERS database

BACKGROUND

Laxatives are widely used in the treatment of constipation, but they also have brought many adverse reactions to patients.

METHODS

We conducted a pharmacovigilance analysis based on the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database to analyze the adverse events of six constipation drugs (linaclotide, lubiprostone, prucalopride, naloxegol, naldemedine, and plecanatide) and to search for clinically meaningful adverse reaction signals. We used disproportionality analysis as the main analysis method to detect pharmacovigilance signals, which includes Frequentist methods and Bayesian methods.

RESULTS

Among the reports of the six drugs, more adverse reactions were reported from females than males, and the number of adverse reactions reported was higher in the group of 60-89 years. Linaclotide had the lowest proportion of serious adverse event reports (4.38%), while naldemedine had the highest proportion of serious adverse event reports (25.57%). According to the classification of system organ classification (SOC), the number of gastrointestinal adverse events (N = 8321) was the largest.

CONCLUSIONS

The adverse reactions of constipation drugs were mainly gastrointestinal symptoms such as diarrhea, abdominal pain and abdominal distension. Linaclotide has the highest safety, and more studies are needed to analyze the cardiovascular safety of lubiprostone.

Peripheral opioid receptor antagonism alleviates fentanyl-induced cardiorespiratory depression and is devoid of aversive behavior

Millions of Americans suffering from Opioid Use Disorders (OUD) face a high risk of fatal overdose due to opioid-induced respiratory depression (OIRD). Fentanyl, a powerful synthetic opioid, is a major contributor to the rising rates of overdose deaths. Reversing fentanyl overdoses has proved challenging due to its high potency and the rapid onset of OIRD. We assessed the contributions of central and peripheral mu opioid receptors (MORs) in mediating fentanyl-induced physiological responses. The peripherally restricted MOR antagonist naloxone methiodide (NLXM) both prevented and reversed OIRD to a degree comparable to that of naloxone (NLX), indicating substantial involvement of peripheral MORs to OIRD. Interestingly, NLXM-mediated OIRD reversal did not produce aversive behaviors observed after NLX. We show that neurons in the nucleus of the solitary tract (nTS), the first central synapse of peripheral afferents, exhibit a biphasic activity profile following fentanyl exposure. NLXM pretreatment attenuates this activity, suggesting that these responses are mediated by peripheral MORs. Together, these findings establish a critical role for peripheral MORs, including ascending inputs to the nTS, as sites of dysfunction during OIRD. Furthermore, selective peripheral MOR antagonism could be a promising therapeutic strategy for managing OIRD by sparing CNS-driven acute opioid-associated withdrawal and aversion observed after NLX.

Significance Statement

In this study, we compare the central versus peripheral components underlying fentanyl-induced cardiorespiratory depression to prevent overdose deaths. Our data indicate that these effects are, at least partially, due to the activation of mu opioid receptors present in peripheral sites. These findings provide insight into peripheral contributions to fentanyl-induced overdoses and could potentially lead to the development of treatments selectively targeting the peripheral system, sparing individuals from the CNS-driven acute opioid withdrawal generally observed with the use of naloxone.

Opioid antagonists: clinical utility, pharmacology, safety, and tolerability

Opioid antagonists block opioid receptors, a mechanism associated with utility in several therapeutic indications. Here, we review the sites of action, clinical uses, pharmacology, and general safety profiles of US Food and Drug Administration (FDA)-approved opioid antagonists. A review of the literature and product labels of opioid antagonists was conducted. The unique clinical uses of approved opioid antagonists are related to their ability to block opioid receptors centrally and/or peripherally. Centrally acting opioid antagonists treat opioid and alcohol use disorders (AUDs) and reverse opioid overdose. Because the opioid system influences weight and metabolism, one opioid antagonist combination product is approved for chronic weight management; another, approved for adults with schizophrenia or bipolar I disorder, mitigates olanzapine-associated weight gain. Peripherally acting opioid antagonists are approved for opioid-induced constipation; another accelerates gastrointestinal recovery after bowel surgery. Opioid antagonists are generally well tolerated; they are not associated with physiologic dependence or abuse. However, opioid antagonists can precipitate acute opioid withdrawal in patients using or undergoing withdrawal from opioid agonists. Likewise, their use can confer a risk for opioid overdose if attempts are made to overcome opioid antagonist blockade of opioid receptors via the intake of additional opioids. Opioid receptor antagonists have diverse therapeutic benefits based on their respective pharmacology and sites of action; understanding their respective nuances facilitates the safe and effective use of these agents.

Improving Diagnosis and Management of Opioid-Induced Constipation (OIC) in Clinical Practice: An Italian Expert Opinion

Opioid-induced constipation (OIC) is a very common and troublesome gastrointestinal side effect following the use of opioids. Despite existing international guidelines, OIC is largely underdiagnosed and undertreated. ECHO OIC is a European project designed to improve the diagnosis and management of OIC at the primary care level. The next phase of the ECHO OIC project is to review and adapt the proposed European pathway at national level, considering the local patient journey and clinical practice. A multidisciplinary group of 12 Italian experts reviewed and discussed the European path and formulated a seven-step guide for the practical management of OIC that is also easily applicable in primary care: 1. When prescribing long-term opioids, the physician should inform the patient of the possibility of the onset of OIC; 2. At opioid prescription, doctors should also prescribe a treatment for constipation, preferably macrogol or stimulant laxatives; 3. The patient should be evaluated for OIC within the second week of initiating opioid treatment, by clinical history and Rome IV criteria; 4. In the presence of constipation despite laxatives, prescription of a PAMORA (Peripherally Acting Mu Opioid Receptor Antagonist) should be considered; 5. When prescribing a PAMORA, prescribing information should be carefully reviewed, and patients should be accurately instructed for appropriate use; 6. Efficacy and tolerability of the PAMORA should be monitored regularly by Bowel Function Index, considering a cut-off of 30 for the possible step-up of OIC treatment; 7. After 4 weeks of treatment, if the efficacy of PAMORA is deemed inadequate, discontinuation of the PAMORA, addition of an anti-constipation drugs, change of opioid type, or referral to a specialist should be considered. Spreading knowledge about the OIC problem as much as possible to the health community is crucial to obtain not only an early treatment of the condition but also to promote its prevention.

[Chronic constipation]

Chronic constipation is one of the most common health disorders in all of medicine. Its extent ranges from mild discomfort, which is usually easy to improve, to severe functional limitations that may significantly reduce quality of life and may be refractory to various treatment approaches. Our understanding of the pathomechanism has grown considerably in recent years and has also led to important new therapeutic developments. The resulting treatment options and recommendations are presented in the current update of the S2k constipation guideline in an evidence-based and practical manner. The respective significance of traditional and recent drug developments is classified and categorized in modern "step-up" treatment strategies. In particular, numerous important aspects of everyday practice are addressed, such as questions on long-term treatment and therapeutic options in specific constellations (adequate treatment of constipation in older people, constipation during pregnancy, and drug-induced [especially opioid-induced]constipation).The most important new developments (i.e. new therapeutic approaches, but also re-evaluations of "traditional" laxatives and the importance of careful diagnostics in therapy-refractory patients) are summarized in this article.

Opioids and the Gastrointestinal Tract: The Role of Peripherally Active µ-Opioid Receptor Antagonists in Modulating Intestinal Permeability

Opioid receptors are found throughout the gastrointestinal tract, including the large intestine. Many patients treated with opioids experience opioid-induced constipation (OIC). Laxatives are not effective in most patients, and in those who do initially respond, the efficacy of laxatives generally diminishes over time. In addition, OIC does not spontaneously resolve for most patients. However, complications of opioids extend far beyond simply slowing gastrointestinal transit. Opioid use can affect intestinal permeability through a variety of mechanisms. Toll-like receptors are a crucial component of innate immunity and are tightly regulated within the gut epithelium. Pathologic µ-opioid receptor (MOR) and toll-like receptor signaling, resulting from chronic opioid exposure, disrupts intestinal permeability leading to potentially harmful bacterial translocation, elevated levels of bacterial toxins, immune activation, and increased cytokine production. Peripherally active MOR antagonists, including methylnaltrexone, are effective at treating OIC. Benefits extend beyond simply blocking the MOR; these agents also act to ameliorate opioid-induced disrupted intestinal permeability. In this review, we briefly describe the physiology of the gastrointestinal epithelial border and discuss the impact of opioids on gastrointestinal function. Finally, we consider the use of peripherally active MOR antagonists to treat disrupted intestinal permeability resulting from opioid use and discuss the potential for improved morbidity and mortality in patients treated with methylnaltrexone for opioid-induced bowel disorders.

Leaky Gut Syndrome: Myths and Management

Leaky gut syndrome is a condition widely popularized in the lay literature, although it is not currently accepted as a formal medical diagnosis. Multiple gastrointestinal symptoms are ascribed to leaky gut syndrome, including diarrhea, bloating, distension, abdominal pain, and dyspeptic symptoms of early satiety, nausea, and postprandial fullness. The etiology and pathophysiology of leaky gut syndrome are multifactorial; a preceding gastrointestinal infection, inflammatory bowel disease, and certain medications may be relevant factors in some patients. The diagnosis of leaky gut syndrome is problematic. Although patients are frequently informed that the diagnosis can be readily made using results from blood work or stool studies, no validated test currently exists to make this diagnosis. Patients report a variety of myths about the etiology, diagnosis, and treatment of leaky gut syndrome, which can cause alarm and can frequently lead to expensive, unnecessary tests and unproven, sometimes dangerous treatments. This article reviews some of the most common myths about leaky gut syndrome and provides data from the scientific literature to correct these statements. Management strategies, based on data, are provided when available.

Opioid-induced Constipation: Old and New Concepts in Diagnosis and Treatment

Daily use of opioid analgesics has significantly increased in recent years due to an increasing prevalence of conditions associated with chronic pain. Opioid-induced constipation (OIC) is one of the most common, under-recognized, and under-treated side effects of opioid analgesics. OIC significantly reduces the quality of life by causing psychological distress, lowering work productivity, and increasing access to healthcare facilities. The economic and social burden of OIC led to the development of precise strategies for daily clinical practice. Key aspects are the prevention of constipation through adequate water intake and fiber support, avoidance of sedentariness, and early recognition and treatment of cofactors that could worsen constipation. Recommended first-line therapy includes osmotic (preferably polyethylene glycol) and stimulant laxatives. Peripherally acting μ-opioid receptor antagonists, such as methylnaltrexone, naloxegol, or naldemedine, should be used in patients that have not responded to the first-line treatments. The bowel functional index is the main tool for assessing the severity of OIC and for monitoring the response. The paper discusses the recent literature on the pathophysiology, clinical evaluation, and management of OIC and provides a pragmatic approach for its assessment and treatment.

Naldemedine is associated with earlier defecation in critically ill patients with opioid-induced constipation: A retrospective, single-center cohort study

INTRODUCTION

There are few reports describing the association of naldemedine with defecation in critically ill patients with opioid-induced constipation. The purpose of this study was to determine whether naldemedine is associated with earlier defecation in critically ill patients with opioid-induced constipation.

METHODS

In this retrospective cohort study, patients admitted to the Intensive Care Unit (ICU) without defecation for 48 hours while receiving opioids were eligible for enrollment. The primary endpoint was the time of the first defecation within 96 hours after inclusion. Secondary endpoints included presence of diarrhea, duration of mechanical ventilation, ICU length of stay, ICU mortality, and in-hospital mortality. The Cox proportional hazard regression analysis with time-dependent covariates was used to evaluate the association naldemedine with earlier defecation.

RESULTS

A total of 875 patients were enrolled and were divided into 63 patients treated with naldemedine and 812 patients not treated. Defecation was observed in 58.7% of the naldemedine group and 48.8% of the no-naldemedine group during the study (p = 0.150). The naldemedine group had statistically significantly prolonged duration of mechanical ventilation (8.7 days vs 5.5 days, p < 0.001) and ICU length of stay (11.8 days vs 9.2 days, p = 0.001) compared to the no-naldemedine group. However, the administration of naldemedine was significantly associated with earlier defecation [hazard ratio:2.53; 95% confidence interval: 1.71-3.75, p < 0.001].

CONCLUSION

The present study shows that naldemedine is associated with earlier defecation in critically ill patients with opioid-induced constipation.

An observational post-authorization safety study (PASS) of naloxegol drug utilization in four European countries

PURPOSE

Naloxegol has been shown to be an efficient alternative to treat opioid-induced constipation (OIC). This study aimed at describing the characteristics of naloxegol users and assessing patterns of naloxegol use and associated factors.

METHODS

This drug utilization cohort study used observational registry data on patients newly prescribed naloxegol in four European countries. Patient characteristics and patterns of naloxegol use and associated factors were described.

RESULTS

A total of 17 254 naloxegol users were identified across the countries. Their median age was 56-71 years, and each country had a majority of women (ranging 57.5%-62.9%). Multiple comorbidities, including cancer, were common. Natural opium alkaloids and osmotically acting laxatives (excluding saline) were the most frequently used opioids and laxatives. Overall prior use of opioids ranged from 91.9% to 99.6% and overall prior use of laxatives ranged from 69.9% to 92.4%. Up to 77.7% had prior use of medications with interaction potential, and up to 44.5% used them concurrently with naloxegol. Naloxegol was discontinued by 55.1%-90.9% of users, typically during the first 30 days. Approximately 10%-30% switched to or augmented the treatment with another constipation medication or restarted naloxegol after discontinuation. Augmentation with another constipation medication was relatively common, suggesting that naloxegol was used for multifactorial constipation.

CONCLUSION

The present study reflects real-world clinical use of naloxegol, including in vulnerable patient groups. Some naloxegol users lacked laxative or regular opioid use within six months before index date or used naloxegol concomitantly with medications presenting an interaction potential.

Peripherally-active mu-opioid receptor antagonists for constipation in critically ill patients receiving opioids: A case-series and a systematic review and meta-analysis of the literature

BACKGROUND

Constipation is frequent in critically ill patients, and potentially related to adverse outcomes. Peripherally-active mu-opioid receptor antagonists (PAMORAs) are approved for opioid-induced constipation, but information on their efficacy and safety in critically ill patients is limited. We present a single-center, retrospective, case-series of the use of naldemedine for opioid-associated constipation, and we systematically reviewed the use of PAMORAs in critically ill patients.

METHODS

Case-series included consecutive mechanically-ventilated patients; constipation was defined as absence of bowel movements for >3 days. Naldemedine was administered after failure of the local laxation protocol. Systematic review: PubMed was searched for studies of PAMORAs to treat opioid-induced constipation in adult critically ill patients.

PRIMARY OUTCOMES

time to laxation, and number of patients laxating at the shortest follow-up.

SECONDARY OUTCOMES

gastric residual volumes and adverse events.

KEY RESULTS

A total of 13 patients were included in the case-series; the most common diagnosis was COVID-19 ARDS. Patients had their first bowel movement 1 [0;2] day after naldemedine. Daily gastric residual volume was 725 [405;1805] before vs. 250 [45;1090] mL after naldemedine, p = 0.0078. Systematic review identified nine studies (two RCTs, one prospective case-series, three retrospective case-series and three case-reports). Outcomes were similar between groups, with a trend toward a lower gastric residual volume in PAMORAs group.

CONCLUSIONS & INFERENCES

In a highly-selected case-series of patients with refractory, opioid-associated constipation, naldemedine was safe and associated to reduced gastric residuals and promoting laxation. In the systematic review and meta-analysis, the use of PAMORAs (mainly methylnaltrexone) was safe and associated with a reduced intolerance to enteral feeding but no difference in the time to laxation.

Management of Constipation in Hospitalized Patients

Constipation is frequently encountered in hospital settings and can have potentially serious consequences yet is often underrecognized and undertreated. Opioid-induced constipation is a common cause of constipation in hospitalized patients. Opioids induce constipation through agonistic effects on enteric µ-opioid receptors. This review aims to provide insight on the identification and management of constipation in inpatient settings, with a particular focus on opioid-induced constipation. Constipation assessment should be routinely initiated at hospital admission and can be facilitated by thorough symptom assessments; relevant patient history, including recent medication use; physical examination; and patient assessment tools developed to evaluate the impact of constipation. Management of opioid-induced constipation should begin with ensuring adequate hydration and electrolyte balance and encouraging patient mobilization. Other treatments may include laxatives, enemas, intestinal secretagogues, peripherally acting µ-opioid receptor antagonists, and manual disimpaction. Surgical intervention may be required for some patients as a salvage therapy in severe, refractory cases.

Real-World Evidence for the Safety and Effectiveness of Naldemedine in the Management of Opioid-Induced Constipation in Patients With Cancer Pain: Post-hoc Subgroup Analysis of Post-marketing Surveillance in Japan

BACKGROUND

Opioid-induced constipation is common and greatly affects the quality of life but is often under-recognised and undertreated. This study aimed to investigate the safety and effectiveness of naldemedine for opioid-induced constipation with cancer pain according to specific subgroups of clinical interest.

METHODS

In this exploratory post-hoc subgroup analysis of post-marketing surveillance from Japan (UMIN: 000042851), data were investigated by the subgroups: age (≥75, <75 years), Eastern Cooperative Oncology Group performance status (PS 0-2, 3-4), constipation severity (mild, moderate, severe), brain metastasis (yes, no), anticancer drug treatment (yes, no), opioid at naldemedine initiation (fentanyl only, only strong opioids other than fentanyl, weak opioids only, other), and prior or concomitant use of laxative (only osmotic/saline laxatives, only stimulant laxatives, other, none). Enrolled patients (n = 1184) received naldemedine (0.2 mg once daily) orally for up to 12 weeks. Regarding safety endpoints, the incidence of adverse drug reactions, including diarrhoea, was determined within each subgroup. Regarding effectiveness endpoints, improvement rates in the frequency and condition of bowel movements were investigated by subgroups.

RESULTS

The incidence of adverse drug reactions, including diarrhoea, among subgroups ranged from 7.74% to 16.08% (diarrhoea: 5.95% to 13.19%), compared to 11.30% (diarrhoea: 9.09%) in the total population. Through week two to week 12, improvement rates in the frequency and condition of bowel movement among subgroups ranged from 63.6% to 89.7% and 67.6% to 94.9%, compared to 75.0% to 83.2% and 80.0% to 88.0% in the total population, respectively.

CONCLUSIONS

Naldemedine was well tolerated and effective in patients with opioid-induced constipation and cancer pain regardless of the subgroups investigated.

Efficacy analysis of enhanced recovery after surgery in laparoscopic-assisted radical resection of type I choledochal cyst

Objective

The objective of this study was to investigate the feasibility and effectiveness of laparoscopic-assisted radical resection of type I choledochal cyst (CC) guided by the principles of enhanced recovery after surgery (ERAS).

Methods

A retrospective cohort study of type I CC admitted to our hospital between May 2020 and December 2021 were analyzed, a total of 41 patients with choledochal cyst underwent surgery during this period and 30 cases were selected based on inclusion and exclusion criteria. Patients (n = 15) who received the traditional treatment from May 2020 to March 2021 were included in the traditional group. Patients (n = 15) who received ERAS from April 2021 to December 2021 were included in the ERAS group. Both groups underwent surgery performed by the same surgical team. Preoperative data of the two groups were recorded, and relevant data were statistically analyzed and compared.

Results

There was a statistically significant difference in the dose of opioids. Significant differences were observed between the ERAS and traditional groups in the results of the FLACC pain assessment scale on the 1st and 2nd day after surgery, time of gastric tube, urinary catheter and abdominal drainage tube removal, time of first defecation after operation, time of first eating after operation, time to reach full food intake, results of CRP, ALB, and ALT on the 3rd and 7th postoperative day, postoperative hospital stay, and total treatment cost. No significant differences were observed between the two groups in terms of gender, age, body weight, cyst size, preoperative CRP, ALB, ALT, intraoperative blood loss, operation time, and the number of cases converted to laparotomy. Neither the FLACC pain assessment scale on the 3rd day after surgery, the incidence of postoperative complications, nor the rate of readmission within 30 days showed significant differences.

Conclusions

Laparoscopic-assisted radical resection of type I CC guided by the principles of ERAS is safe and effective for children. The ERAS concept demonstrated advantages over traditional laparoscopic surgery, including reduced opioid use, shorter time to first postoperative defecation, earlier resumption of postoperative feeding, shorter time to reach full feeding, shorter postoperative hospital stay, and lower total treatment cost.

Subcutaneous Methylnaltrexone as Treatment for Opioid-Induced Constipation in Patients with Advanced Cancer and Noncancer Illnesses: A Post Hoc Analysis of Two Clinical Trials

Purpose

To evaluate the efficacy and safety of subcutaneous (SC) methylnaltrexone for opioid-induced constipation (OIC) in patients with and without active cancer.

Patients and Methods

We analyzed two randomized, double-blind, placebo-controlled, Phase 3/4 trials (NCT00402038, NCT00672477). Patients received SC methylnaltrexone (study 302, 0.15 mg/kg; study 4000, 8 mg or 12 mg based on body weight) or placebo every other day for 2 weeks. Patients were stratified by cancer status. Primary efficacy endpoints included proportion of patients achieving rescue-free laxation (RFL); secondary endpoints included time to RFL, pain intensity scores, and safety/tolerability. Trial results were evaluated separately.

Results

The safety population (patients receiving ≥1 study drug dose) included 364 patients (study 302, n=134; study 4000, n=230). Study 302 had 78 patients with active cancer (methylnaltrexone, n=37; placebo, n=41) and 56 without cancer (methylnaltrexone, n=26; placebo, n=30); study 4000 had 152 patients with active cancer (methylnaltrexone, n=79; placebo, n=73) and 78 without cancer (methylnaltrexone, n=37; placebo, n=41). A significantly greater proportion of patients treated with methylnaltrexone achieved a laxation response within 4 hours after at least 2 of the first 4 doses versus placebo, dosed by body weight (cancer, 54.1% [methylnaltrexone] vs 7.3% [placebo], P<0.0001; noncancer, 48.0% vs 10.0%; P<0.005) or given as a weight-adjusted fixed dose (cancer, 59.5% vs 6.8%; noncancer, 70.3% vs 14.6%; P<0.0001 each). With fixed-dose methylnaltrexone, average time to RFL for patients with and without cancer was <1 hour of the first dose; with methylnaltrexone dosed by body weight, the first RFL occurred in <4 and <7 hours of treatment in patients with and without cancer, respectively. No significant differences were found in pain scores. SC methylnaltrexone was well tolerated at all doses in all patient cohorts.

Conclusion

SC methylnaltrexone was efficacious in inducing rapid RFL and safe among patients with and without active cancer suffering from OIC.

Multidisciplinary approach, continuous care and opioid management in cancer pain: case series and review of the literature

Underlying cancer pain has heterogenous aetiologies and mechanisms. It requires detailed and comprehensive pain assessment, combined with personalized treatment. A multidisciplinary team is essential to providing the best management of cancer pain at every disease stage, improving the quality of life and outcomes in patients with cancer. This narrative literature review emphasizes the value of providing all patients with multidisciplinary pain management in their preferred care setting. Real-life experiences are also reported to witness the efforts of physicians to properly manage cancer pain. This article is part of the Management of breakthrough cancer pain Special Issue: https://www.drugsincontext.com/special_issues/management-of-breakthrough-cancer-pain.

Management of Opioid-induced Constipation in Older Adults

Opioid-induced constipation (OIC) is a common condition in older adults who may not be responsive to traditional laxative therapy. OIC is defined as new or worsening constipation symptoms that occur with initiation of or altering the dose of opioid analgesia. For adult patients with OIC and noncancer pain, we recommend considering nonpharmacologic interventions (eg, dietary measures, increased physical activity, and biofeedback training) and over-the-counter laxatives, followed by prescription opioid receptor antagonists (methylnaltrexone, naloxegol, and naldemedine) if traditional over-the-counter laxatives fail. Other options may include lubiprostone, linaclotide, plecanatide, and prucalopride; however, these are not indicated for OIC specifically or studied in older adults. Because of the complex nature of absorption, distribution, metabolism, and excretion in the aging population, all agents used to treat OIC must be evaluated individually and reevaluated as patients continue to age. This review will serve as a guide to managing OIC in older adults.

Consideration of Symptom Management in Advanced Heart Failure

This work provides an opinion on palliative care for people with heart disease. The work focuses on the management of key symptoms associated with both end stage heart disease, applying a palliative approach and suggesting treatment options. The work also indicates the potential for greater collaboration of specialist teams including specialist palliative care in the assessment and management of patients with complex needs as they progress through their disease trajectory. The practical application of evidence-based guidelines and recommendations is key to the successful individualised management of complex symptoms.

A Survey of the Incidence of Constipation in Patients with Chronic Non-cancer Pain Using Opioid Analgesics in Japan

INTRODUCTION

Although opioids have potent analgesic properties, their use is associated with side effects, including opioid-induced constipation (OIC). This study investigated the incidence of OIC based on the Rome IV diagnostic criteria in patients using opioid analgesics for chronic non-cancer pain and to explore and compare the risk factors for the development of OIC in opioid analgesic users.

METHODS

We surveyed patients aged 20 years or more living in Japan via the internet; who had been using opioid or non-opioid analgesics (N = 500 each) for at least 3 months for relief from chronic non-cancer musculoskeletal pain (low back pain or osteoarthritis); and who provided electronic consent to participate in and complete the survey. The groups were matched for age and sex.

RESULTS

Of the patients using opioid analgesics, 89% were taking weak opioids. The proportion of patients perceiving constipation was comparable between the opioid and non-opioid analgesic groups (34% vs 29%, respectively); however, a significantly higher proportion of patients in the opioid group, compared to the non-opioid group, reported self-assessed constipation (40% vs 18%, respectively) after using an analgesic and fulfilled two or more symptoms of the Rome IV diagnostic criteria for constipation (28% vs 19%, respectively). A higher proportion of patients were taking prescribed medicine for constipation in the opioid group compared with the non-opioid group (33% vs 18%, respectively). Low back pain, but not opioid strength and scheduled dosing, was identified as a risk factor for OIC among various covariates assessed in the logistic regression analysis in 81 patients with OIC and Rome IV diagnosis vs 419 patients without OIC in the opioid group.

CONCLUSION

Use of opioid analgesics, including weak opioids, for treating chronic non-cancer musculoskeletal pain is associated with OIC. This finding highlights the need for appropriate treatment of constipation in patients with chronic non-cancer pain in Japan.

TRIAL REGISTRATION

UMIN000043985.

Opioid-Induced Constipation in Real-World Practice: A Physician Survey, 1 Year Later

INTRODUCTION

Opioid-induced constipation (OIC) is the most common adverse effect of opioid therapy, but it is underdiagnosed and undertreated. Last year, a survey among Italian healthcare providers revealed important differences in the clinical management of OIC across physician specialties, the need of standardization of diagnosis and treatment, and the urgency of further education. Herein, we submitted an updated version of the survey to the same cohort of experts to evaluate potential progress.

METHODS

The online survey included 15 questions about OIC. Responses were analyzed descriptively and aggregated by physician specialty.

RESULTS

A total of 190 physicians completed the survey. Most respondents (65%) did not feel adequately educated about OIC despite general consensus regarding interest in the topic and acknowledgement of OIC impact on patients' QoL and adherence to opioid therapy. Overall, 55-77% of physicians regularly evaluated intestinal function or OIC symptoms in patients receiving opioid therapy, with one-third of respondents implementing it in the past year. Even though the most common method for assessment was still patient diary, the use of specific scales underwent a small but significant increase compared to the previous year, with major implementation in the use of Rome IV criteria. As regards first-line treatment, most respondents (49%) preferred macrogol prophylaxis followed by macrogol plus another laxative. For second-line treatment, we revealed a growth in the prescription of peripherally acting mu-opioid receptor antagonists (PAMORAs), with 46% of all the respondents having increased their use during the past year.

CONCLUSIONS

Despite some limitations, our study demonstrated a slow but important step closer to standardization of diagnosis and treatment of OIC. Further educational and training efforts should be put in place to favor best evidence-based clinical practice.

Antinociceptive activities and mechanism of action of Cepharanthine

Cepharanthine is an alkaloid that isolated from Stephania cepharantha Hayata, however，its analgesic properties are unclear and the molecular targets that mediating Cepharanthine-induced analgesia are not explored yet. In the current study, mice pain models including hot plate, acetic acid-induced writhing and formalin tests were conducted to evaluate the antinociceptive actions of Cepharanthine. [³H]-ligand competitive binding assay was applied to determine the binding affinity and selectivity of Cepharanthine at κ, μ and δ opioid receptors. Cepharanthine-induced constipation was investigated using the small intestinal transit test. The results showed that intraperitoneal injection of Cepharanthine produced potent antinociception with an ED₅₀ value of 24.5 mg/kg in the acetic acid-induced writhing test. In the formalin test, Cepharanthine produced moderate antinociception with the maximum analgesic activity of 42.6 ± 11.3% in phase I and 60.1 ± 7.7% in phase Ⅱ, respectively. Cepharanthine had no effects in the hot plate test. In vitro radioligand binding assay, Cepharanthine exhibited a high affinity for μ opioid receptors with a Ki value of 80 nM, without binding to κ and δ opioid receptors. Correspondingly, Cepharanthine-mediated antinociceptive effects were antagonized by pretreatment with opioid receptor antagonist naloxone. Cepharanthine also decreased the small intestine propulsion rates in the small intestinal transit test. Together, this study firstly demonstrates that Cepharanthine produces potent antinociception in acetic acid-induced visceral pain and moderate antinociception in formalin-induced inflammatory pain, and its mechanism of action may be through activation of μ opioid receptors.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 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).

Rational Design, Chemical Syntheses, and Biological Evaluations of Peripherally Selective Mu Opioid Receptor Ligands as Potential Opioid Induced Constipation Treatment

Opioid-induced constipation (OIC) is a common adverse effect of opioid analgesics. Peripherally acting μ opioid receptor antagonists (PAMORAs) can be applied in the treatment of OIC without compromising the analgesic effects. NAP, a 6β-N-4-pyridyl-substituted naltrexamine derivative, was previously identified as a potent and selective MOR antagonist mainly acting peripherally but with some CNS effects. Herein, we introduced a highly polar aromatic moiety, for example, a pyrazolyl or imidazolyl ring to decrease CNS MPO scores in order to reduce passive BBB permeability. Four compounds 2, 5, 17, and 19, when administered orally, were able to increase intestinal motility during morphine-induced constipation in the carmine red dye assays. Among them, compound 19 (p.o.) improved GI tract motility by 75% while orally administered NAP and methylnaltrexone showed no significant effects at the same dose. Thus, this compound seemed a promising agent to be further developed as an oral treatment for OIC.

A Prospective, Real-World, Multinational Study of Naloxegol for Patients with Cancer Pain Diagnosed with Opioid-Induced Constipation-The NACASY Study

The Naloxegol Cancer Study (NACASY) was a multinational European study aimed to evaluate the 4-week safety and efficacy of naloxegol in a real-world setting in patients with cancer pain diagnosed with opioid-induced constipation. The primary safety endpoint was the incidence of adverse events leading to study discontinuation. We recruited 170 patients who received at least one dose of naloxegol (i.e., safety population). Out of 170 patients, 20 (11.8%, 95%CI 6.9-16.6) discontinued the study due to adverse events, and, of them, 12 (7.1%, 95%CI 3.2-10.9%) were study discontinuations due to naloxegol-related adverse events. From 76 patients subjects who had completed both 4 weeks of treatment and 28 days of the diary, 55 patients (72.4%, 95% CI 62.3-82.4%) were regarded as responders (i.e., showed ≥3 bowel-movements per week and an increase of ≥1 bowel-movement over baseline) to naloxegol treatment. The Patient Assessment of Constipation-Quality of Life Questionnaire total score and all its subscales improved from baseline to 4 weeks of follow up. Our findings support and provide new evidence about the beneficial effect of naloxegol in terms of improvement of constipation and quality-of-life in patients with cancer-related pain and opioid-induced constipation and show a safety profile consistent with previous pivotal and real-world studies.

Prevalence of drug-induced constipation and severity of associated biopsychosocial effects in patients with nonmalignant pain: a cross-sectional review of depersonalized data from the German Pain e-Registry

BACKGROUND

Drug-induced constipation (DIC) is a well-known comorbidity of cancer pain, however, data on its prevalence in nonmalignant pain (NMP) and its biopsychosocial effects are few.

OBJECTIVE

To assess the prevalence and impact of DIC in patients with NMP.

METHODS

Exploratory noninterventional, retrospective, cross-sectional analysis of depersonalized routine data of the German Pain e-Registry on 150,488 NMP patients (EUPAS identifier: 42286).

RESULTS

DIC affects 33.5% of NMP patients. The most prevalent risk factors were the use of strong opioid analgesics and analgesic polymedication. Patients with DIC presented with significantly worse biopsychosocial scores as well as significantly higher percentages of individuals with severe deterioration of pain, daily life activities, physical and mental quality of life, mood, and overall wellbeing. Among patients with DIC, those who reported constipation as a clinical symptom and who documented bowel-function index (BFI) scores above the reference range were significantly more affected compared to those who either reported only constipation as an adverse event or elevated BFI scores. 55.9% of patients with DIC reported the use of laxatives, mostly over-the-counter preparations (43.6%), whereas prescription laxatives were taken by only 29.3%.

CONCLUSIONS

DIC is a frequent comorbidity of pain management and affects around one-third of patients with NMP. It interferes significantly with pain-related biopsychosocial effects and has to be addressed specifically to improve the overall burden in affected patients. However, the use of laxatives was significantly less frequent than recommended indicating significant room for improvement.

Impact and Consequences of Opioid-Induced Constipation: A Survey of Patients

INTRODUCTION

Opioids are a valuable tool to help achieve control of pain. However, opioid-induced constipation (OIC) is an important limitation of treatment with this class of drugs.

METHODS

To better understand the impact of OIC on patient-reported outcomes, we carried out a survey involving patients being treated with opioids. Both ad hoc questions and the PROMIS and PAC-SYM and PAC-QOL scores were used.

RESULTS

Of the 597 participants, 150 (25%) had cancer-related pain, and 447 (75%) had non-cancer pain; 66% experienced OIC. PROMIS pain interference questions indicated that pain is more likely to interfere with a patient's life when they have OIC. PAC-QOL and PAC-SYM revealed that 58% of patients with non-cancer pain and OIC reported at least one "severe" or "very severe" constipation symptom, compared to 83% with cancer-related pain. Younger age and less time on opioids were associated with greater impact of OIC on quality of life. Only 41% of patients were satisfied with how their constipation was managed. Over 50% of those with non-cancer pain said that they modified their opioid regimen due to constipation, vs. 6% of those with cancer pain. Constipation had been discussed with the healthcare provider (HCP) in 48% of non-cancer patients and in 73% of cancer patients. In those with chronic pain and OIC, 24% expressed varying degrees of dissatisfaction with the healthcare system, vs. 37% in those with cancer pain and OIC.

CONCLUSION

Our results provide additional evidence that management of OIC is inadequate in many cases. Moreover, they indicate that there is a definite need for better education about OIC among HCPs.

Advances in Oncoanaesthesia and Cancer Pain

INTRODUCTION

The growing interest on how peri-‑operative interventions, especially regional anesthesia, during cancer surgery can alter oncological outcome increasing disease free survival is probably responsible for the birth of the new subspecialty called onco-anesthesia. A paradigm shift in the concept of anesthetic management has occurred recently owing to the innumerable diverse revelations from the ongoing research in this field.

DISCUSSION

Long lasting but reversible epigenetic changes can occur due to surgical stress and perioperative anesthetic medications. The exact relationship between these factors and tumor biology is being studied further. A popular topic under research now is the influence of regional anesthesia on cancer recurrence. Combining nerve blocks with total intravenous anesthesia (TIVA) brings down the requirement of opioids and volatile anesthetic agents implicated in cancer recurrence. The study of mechanism of pain at the molecular level has led to the discovery of novel modes of prevention of chronic post-surgical pain. Newer combination aggressive treatment therapies -intraoperative chemotherapy and radiotherapy, isolated limb perfusion, photodynamic therapy and robotic surgery require specialized anesthetic management. The COVID pandemic introduced new guidelines for safe management of oncosurgical patients .Use of genomic mapping to personalize pain management will be the breakthrough of the decade.

CONCLUSION

The discovery that anesthetic strategy could have significant oncological sequel is a quantum leap forward. Avoiding some anesthetic medications may decrease cancer recurrence. Comprehensive cancer care and translational research will pave the way to uncover safe anesthetic practices.

The effect of opioids on gastrointestinal function in the ICU

Gastrointestinal (GI) dysfunction is common in the critical care setting and is highly associated with clinical outcomes. Opioids increase the risk for GI dysfunction and are frequently prescribed to reduce pain in critically ill patients. However, the role of opioids in GI function remains uncertain in the ICU. This review aims to describe the effect of opioids on GI motility, their potential risk of increasing infection and the treatment of GI dysmotility with opioid antagonists in the ICU setting.

Opioid-Induced Constipation and Acupuncture: A Case Discussion

BACKGROUND

Use of acupuncture for treatment of functional constipation is well studied; however, studies examining use of acupuncture for opioid-induced constipation are limited.

CASE DESCRIPTION

A 70-year-old woman with newly diagnosed multiple myeloma discovered after presentation to the emergency room with severe back pain. Pain management required use of opioids, escalating to effect. Hospital course was complicated by opioid-induced constipation causing abdominal pain, nausea, and ileus despite aggressive titration of stimulant and osmotic laxatives as well as administration of suppositories and enemas on multiple occasions. Prior to nasogastric tube placement for the ileus, the patient requested acupuncture treatment in attempt to relieve constipation. Shortly after acupuncture session, patient passed multiple stools with improvement in abdominal pain and nausea and avoidance of nasogastric tube.

CONCLUSION

Acupuncture for opioid-induced constipation may provide symptom relief through use of nonpharmacologic interventions; however, further studies are needed to determine the optimal therapeutic approach.

Pain in sickle cell disease: current and potential translational therapies

Pain is a major comorbidity of sickle cell disease (SCD). Patients with SCD may suffer from both acute and chronic pain. Acute pain is caused by recurrent and unpredictable episodes of vaso-occlusive crises (VOC), whereas the exact etiology of chronic pain is still unknown. Opioids are the mainstay for pain treatment, but the opioid epidemic has significantly altered access to prescription opioids and has brought concerns over their long-term use into the forefront, which have negatively impacted the treatment of sickle pain. Opioids remain potent analgesics but growing opioid-phobia has led to the realization of an unmet need to develop nonopioid therapies that can provide relief for severe sickle pain. This realization has contributed to the approval of 3 different drugs by the Food and Drug Administration (FDA) for the treatment of SCD, particularly to reduce VOC and/or have an impact on the pathobiology of SCD. In this review, we outline the challenges and need for validation of side-effects of opioids and provide an update on the development of mechanism-based translational therapies, specifically targeting pain in SCD.

Common Clinical Practice for Opioid-Induced Constipation: A Physician Survey

Background

Opioid-induced constipation (OIC) remains an important clinical obstacle despite the availability of several guidelines and pharmacological options for its management. Here, we surveyed common practices and perceptions about OIC among physicians who prescribe opioids in Italy.

Methods

The online survey included 26 questions about OIC. Responses were analyzed descriptively and aggregated by physician specialty.

Results

A total of 501 physicians completed the survey. Most respondents (67%) did not feel adequately educated about OIC despite general consensus regarding interest in the topic. Overall, 62–75% of physicians regularly evaluated intestinal function or OIC symptoms in patients receiving opioid therapy. The most common method for assessment was patient diary; few physicians used a validated instrument such as the Rome IV criteria. Psychiatrists and addiction specialists showed the lowest interest and poorest practices. Most respondents (78%) preferred macrogol prophylaxis followed by macrogol plus another laxative for first-line treatment of OIC symptoms. Peripheral-acting mu opioid receptor antagonists (PAMORAs) were not widely used among physicians; 61% had never prescribed a PAMORA for OIC.

Conclusion

Our findings reveal important differences in clinical practice for OIC across physician specialties. Additional formative efforts are necessary to improve awareness about best practices in OIC.

Opioid-induced Constipation: A Review of Health-related Quality of Life, Patient Burden, Practical Clinical Considerations, and the Impact of Peripherally Acting μ-Opioid Receptor Antagonists

Objective:

The objective of this study was to provide an overview of opioid-induced constipation (OIC) and its influence on disease burden and quality of life (QOL).

Methods:

This is a narrative review.

Results:

For many patients, opioid-related side effects, the most common being OIC, have the potential to significantly impair patients’ QOL. Patients with OIC often experience substantial overall burden (ie, increases in anxiety and depression, impairments in activities of daily living, low self-esteem, feelings of embarrassment) and economic burden (ie, higher health care costs, more frequent doctor visits, increased out-of-pocket medication costs), which often causes patients to modify or discontinue opioid treatment despite the analgesic benefits. OIC occurs when opioids bind to peripheral μ-opioid receptors in the gastrointestinal tract. Currently, 4 Food and Drug Administration (FDA)-approved medications are available for OIC, 3 of which are peripherally acting µ-opioid receptor antagonists (PAMORAs). PAMORAs block µ-opioid receptors in the gastrointestinal tract without affecting the central analgesic effects of the opioid and thus provide a targeted approach to OIC management. Two PAMORAs, naldemedine and methylnaltrexone, have shown significant improvements in QOL based on the Patient Assessment of Constipation Symptoms questionnaire relative to placebo. Along with pharmacologic management for OIC, health care providers should institute comprehensive communication strategies with patients to ensure OIC is effectively recognized and managed.

Discussion:

OIC has both physical and psychological impacts on patients. PAMORAs provide effective relief of OIC while also improving QOL. To augment the pharmacologic management of OIC, proactive counseling approaches between physicians and patients may help relieve some of the patient burden associated with OIC and lead to improved outcomes.

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.

Pharmacological characterization of naloxegol: In vitro and in vivo studies

Opioid-induced constipation is the most prevalent adverse effect of opioid drugs. Peripherally acting mu opioid receptor antagonists (PAMORAs), including naloxegol, are indicated for the treatment of opioid-induced constipation. The aim of this study was the in vitro and in vivo pharmacological characterization of naloxegol in comparison with naloxone. In vitro experiments were performed to measure calcium mobilization in cells coexpressing opioid receptors and chimeric G proteins and mu receptor interaction with G protein and β-arrestin 2 using bioluminescence resonance energy transfer. In vivo experiments were performed in mice to measure pain threshold using the tail withdrawal assay and colonic transit using the bead expulsion assay. In vitro, naloxegol behaved as a selective and competitive mu receptor antagonist similarly to naloxone, being 3-10-fold less potent. In vivo, naloxone was effective in blocking fentanyl actions when given subcutaneously (sc), but not per os (po). In contrast, naloxegol elicited very similar effects with sc or po administration counteracting in a dose dependent manner the constipating effects of fentanyl without interfering with the fentanyl mediated analgesia. Thus, a useful PAMORA action could be obtained with naloxegol both after po and sc administration.

Personalizing Cancer Pain Therapy: Insights from the Rational Use of Analgesics (RUA) Group

Introduction

A previous Delphi survey from the Rational Use of Analgesics (RUA) project involving Italian palliative care specialists revealed some discrepancies between current guidelines and clinical practice with a lack of consensus on items regarding the use of strong opioids in treating cancer pain. Those results represented the basis for a new Delphi study addressing a better approach to pain treatment in patients with cancer.

Methods

The study consisted of a two-round multidisciplinary Delphi study. Specialists rated their agreement with a set of 17 statements using a 5-point Likert scale (0 = totally disagree and 4 = totally agree). Consensus on a statement was achieved if the median consensus score (MCS) (expressed as value at which at least 50% of participants agreed) was at least 4 and the interquartile range (IQR) was 3–4.

Results

This survey included input from 186 palliative care specialists representing all Italian territory. Consensus was reached on seven statements. More than 70% of participants agreed with the use of low dose of strong opioids in moderate pain treatment and valued transdermal route as an effective option when the oral route is not available. There was strong consensus on the importance of knowing opioid pharmacokinetics for therapy personalization and on identifying immediate-release opioids as key for tailoring therapy to patients’ needs. Limited agreement was reached on items regarding breakthrough pain and the management of opioid-induced bowel dysfunction.

Conclusion

These findings may assist clinicians in applying clinical evidence to routine care settings and call for a reappraisal of current pain treatment recommendations with the final aim of optimizing the clinical use of strong opioids in patients with cancer.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40122-021-00248-x.

Methylnaltrexone crosses the blood-brain barrier and attenuates centrally-mediated behavioral effects of morphine and oxycodone in mice

BACKGROUND

Antagonism of peripheral opioid receptors by methylnaltrexone (MNTX) was recently proposed as a potential mechanism to attenuate the development of opioid analgesic tolerance based on experiments conducted in mice. However, reports indicate that MNTX is demethylated to naltrexone (NTX) in mice, and NTX may subsequently cross the blood-brain barrier to antagonize centrally-mediated opioid effects. The goal of this study was to determine whether MNTX alters centrally-mediated behaviors elicited by the opioid analgesics, morphine and oxycodone, and to quantify concentrations of MNTX and NTX in blood and brain following their administration in mice.

METHODS

Combinations of MNTX and morphine were tested under acute and chronic conditions in thermal nociceptive assays. Effects of MNTX and NTX pretreatment were assessed in an oxycodone discrimination operant procedure. Blood and brain concentrations of these antagonists were quantified after their administration using liquid chromatography-mass spectrometry.

RESULTS

MNTX dose-dependently attenuated acute and chronic morphine antinociception. MNTX and NTX dose-dependently antagonized the discriminative stimulus effects of oxycodone. MNTX and NTX were detected in both blood and brain after administration of MNTX, confirming its demethylation and demonstrating that MNTX itself can cross the blood-brain barrier.

CONCLUSIONS

These results provide converging behavioral and analytical evidence that MNTX administration in mice attenuates centrally-mediated effects produced by opioid analgesics and results in functional concentrations of MNTX and NTX in blood and brain. Collectively, these findings indicate that MNTX cannot be administered systemically in mice for making inferences that its effects are peripherally restricted.

Gastrointestinal dysmotility in a patient with advanced lung cancer: paraneoplastic or drug-induced?

A 75-year-old man was hospitalised for bronchoscopy with biopsy due to a suspicious pulmonary mass at chest tomography. He had significant dyspnoea, constipation, nausea, vomiting, anorexia and a 33% loss of weight in the past 3 months. Biopsy revealed a pulmonary squamous cell carcinoma, which was inoperable. Tramadol used at home for 3 months was replaced by morphine on admission. The patient remained constipated despite prokinetics and laxatives, leading to the diagnostic hypothesis of paraneoplastic motility disorder and opioid-induced constipation. Abdominal tomography ruled out the possibility of mechanical obstruction. As complications, the patient presented superior vena cava syndrome and opioid (morphine) intoxication. The patient died a few days later. The management of this case highlights the importance of multidisciplinary care and the challenges of palliative oncology care. Paraneoplastic motility disorder must always be considered among the mechanisms of intestinal dysfunction in patients with advanced oncological disease.

What to Do and What Not to Do in the Management of Opioid-Induced Constipation: A Choosing Wisely Report

Introduction

Despite the essential utility of opioids for the clinical management of pain, opioid-induced constipation (OIC) remains an important obstacle in clinical practice. In patients, OIC hinders treatment compliance and has negative effects on quality of life. From a clinician perspective, the diagnosis and management of OIC are hampered by the absence of a clear, universal diagnostic definition across disciplines and a lack of standardization in OIC treatment and assessment.

Methods

A multidisciplinary panel of physician experts who treat OIC was assembled to identify a list of ten corrective actions—five “things to do” and five “things not to do”—for the diagnosis and management of OIC, utilizing the Choosing Wisely methodology.

Results

The final list of corrective actions to improve the diagnosis and clinical management of OIC emphasized a need for: (i) better physician and patient education regarding OIC; (ii) systematic use of diagnostically validated approaches to OIC diagnosis and assessment (i.e., Rome IV criteria and Bristol Stool Scale, respectively) across various medical contexts; and (iii) awareness about appropriate, evidence-based treatments for OIC including available peripheral mu-opioid receptor antagonists (PAMORAs).

Conclusions

Physicians who prescribe long-term opioids should be forthcoming with patients about the possibility of OIC and be adequately versed in the most recent guideline recommendations for its management.

Novel Analgesics with Peripheral Targets

A limited number of peripheral targets generate pain. Inflammatory mediators can sensitize these. The review addresses targets acting exclusively or predominantly on sensory neurons, mediators involved in inflammation targeting sensory neurons, and mediators involved in a more general inflammatory process, of which an analgesic effect secondary to an anti-inflammatory effect can be expected. Different approaches to address these systems are discussed, including scavenging proinflammatory mediators, applying anti-inflammatory mediators, and inhibiting proinflammatory or facilitating anti-inflammatory receptors. New approaches are contrasted to established ones; the current stage of progress is mentioned, in particular considering whether there is data from a molecular and cellular level, from animals, or from human trials, including an early stage after a market release. An overview of publication activity is presented, considering a IuPhar/BPS-curated list of targets with restriction to pain-related publications, which was also used to identify topics.