Opioid-induced constipation: challenges and therapeutic opportunities

Strategies, Technologies, and Tips for Successful Cecal Intubation

Successful cecal intubation is crucial in ensuring a complete evaluation of the colonic mucosa. Although completion of colonoscopies should be successful in close to 100% of all examinations in the hands of experienced gastroenterologists, there are some patients with colons which can be difficult to navigate. Factors such as older age, presence of diverticular disease, as well as high or low body mass index can present challenges for endoscopists. Challenges can be divided into those that are left sided and are associated with severe angulations of the colon versus those that are right sided and present as redundant colons. Both require different strategies to achieve completion. This review will cover methods, technologies as well the evolution of colonoscope insertion tubes which can help in navigating colons, especially those that are challenging. There will also be a discussion about basic principles and techniques that should be employed in all colonoscopies.

Effects of opium tincture on gastrointestinal function and motility in healthy volunteers: A magnetic resonance imaging study

BACKGROUND

Opioids inhibit motility and secretion of the gut and have been used for antidiarrheal treatment for centuries. However, the underlying mechanisms of opium tincture are not evident.

AIM

To investigate the effects of opium tincture on gastrointestinal motility, intestinal volumes, and water content of different gut segments assessed by magnetic resonance imaging (MRI).

METHODS

Twenty healthy volunteers were included in a randomized, placebo-controlled, crossover study of 9 days of treatment with 30 drops of opium tincture per day. MRI was performed on day 1 (before treatment) and day 9 (during treatment). Measurements included assessments of gastric volume, gastric emptying, gastric motility, small bowel volume, small bowel water content, small bowel motility, colon volume, colon water content, and whole gut transit.

KEY RESULTS

Opium tincture delayed gastric emptying by a mean difference of 5.6 min [95% CI: 1.8-9.4], p = 0.004, and increased postprandial gastric meal volume (17-21%, p = 0.02). Small bowel endpoints did not change. Opium tincture delayed whole gut transit time (p = 0.027) and increased ascending colon volume by 59 mL [95% CI: 15-103], p = 0.004, and transverse colon volume by 48 mL [95% CI: 4-92], p = 0.027. T1-relaxation time of the descending colon chyme was decreased during opium treatment, indicating dryer feces (difference: -173 ms [95% CI: -336 -11], p = 0.03).

CONCLUSION AND INFERENCES

Opium tincture induced changes in the stomach and colon in healthy volunteers. An improved understanding of how opioids affect gut functions may lead to a better understanding and optimized management of diarrhea.

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.

Stercoral perforation of the sigmoid colon secondary to chronic heroin use: A case report and a review of the literature

INTRODUCTION

Stercoral perforation of the colon is a rare and life-threatening condition caused by pressure necrosis due to fecal impaction. It is commonly associated with chronic constipation, particularly in patients with neurogenic bowel disorders or prolonged opioid use. However, its occurrence in the context of chronic heroin use is rarely reported.

CASE PRESENTATION

We report the case of a 40-year-old male with a 5-year history of heroin abuse who presented with diffuse abdominal pain, vomiting, and cessation of gas and stool passage for 10 days. Physical examination revealed a distended abdomen with generalized tenderness, guarding, and a rectal examination confirmed fecal impaction. Computed tomography (CT) showed massive fecal impaction in the sigmoid colon with pneumoperitoneum, indicating perforation. The patient underwent urgent exploratory laparotomy, revealing two perforations in the sigmoid colon with extensive fecal peritonitis. A segmental resection of the sigmoid colon with colostomy was performed. Postoperatively, the patient required intensive care for septic shock but eventually recovered and was referred to an addiction treatment program.

DISCUSSION

This case highlights the serious gastrointestinal complications associated with chronic opioid use, particularly heroin. The pathophysiology involves opioid-induced inhibition of gastrointestinal motility, leading to chronic constipation, fecaloma formation, and subsequent perforation. Early recognition and prompt surgical intervention are crucial in managing stercoral perforation, which carries a high mortality rate if delayed.

CONCLUSION

This case underscores the importance of recognizing gastrointestinal risks in chronic opioid users, especially heroin, and the need for integrated care strategies to prevent severe complications like stercoral perforation.

Beyond the Surface: A Narrative Review Examining the Systemic Impacts of Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare genetic disease resulting from inadequate type VII collagen (C7). Although recurrent skin blisters and wounds are the most apparent disease features, the impact of C7 loss is not confined to the skin and mucous membranes. RDEB is a systemic disease marred by chronic inflammation, fibrotic changes, pain, itch, and anemia, significantly impacting QOL and survival. In this narrative review, we summarize these systemic features of RDEB and promising research avenues to address them.

Population Pharmacokinetics of Naloxegol in Pediatric Subjects Receiving Opioids

The pharmacokinetics (PK) of naloxegol were characterized in pediatric subjects, aged 6 months or older to less than 18 years who either have or are at risk of developing opioid-induced constipation following single dose administration. Subjects grouped as aged 12 years or older to less than 18 years, 6 months or older to less than 12 years, and 6 months or older to less than 6 years, received a single oral dose of naloxegol at doses that were estimated to achieve plasma exposures comparable to adult 12.5- or 25-mg doses. Intensive and sparse plasma naloxegol samples were collected to assess naloxegol concentrations. Data were combined with previously collected adult PK data and used to estimate PK parameters using population PK analyses. Naloxegol PK was described using a 2-compartment model with Weibull-type absorption. Neither age nor body weight was identified as a significant covariate indicating similar PK properties in adult and pediatric subjects. PK estimates in the youngest age group were approximately 80% less than those in adults (12.5-mg equivalent dose). Exposures in the other pediatric groups were similar to those in adult equivalent doses. The PK of naloxegol were characterized as linear over the dose range, with no clinically significant covariates and comparable PK characteristics in adults and pediatric subjects aged 6 months or older.

The effect of acupuncture on gastrointestinal recovery after abdominal surgery: a narrative review from clinical trials

Abdominal surgery is a critical surgery, with more and more attention being paid to postoperative life quality and associated complications in recent years. Among these complications, postoperative gastrointestinal dysfunction is the most common complication of abdominal surgery. Acupuncture therapy is a treatment approach based on the Traditional Chinese Medicine theory, and its feasibility in aiding gastrointestinal recovery after abdominal surgery is supported by both Traditional Chinese Medicine theory and animal experiments. A lot of clinical research has been conducted to evaluate its efficacy, albeit with limitations, and at preliminary stages. Moreover, intervention timing, acupoint selection, and patient benefits should also be considered in clinical practices. This article summarizes the progress of clinical research on acupuncture therapy in gastrointestinal recovery after abdominal surgery and discusses related issues and operations, with the aim to provide new insights and prospects for the incorporation of acupuncture into the Enhanced Recovery After Surgery protocol.

The safety and effectiveness of naldemedine for opioid-induced constipation in patients with advanced cancer in real-world palliative care settings: a multicenter prospective observational study

PURPOSE

In this study, we aimed to evaluate the safety and effectiveness of naldemedine for treating opioid-induced constipation (OIC) in patients with advanced cancer, who are receiving palliative care, and particularly explored its early effects.

METHODS

Palliative care teams and inpatient palliative care units across 14 institutions in Japan were included in this multicenter, prospective, observational study. Patients who were newly prescribed a daily oral dose of 0.2 mg naldemedine were enrolled. The spontaneous bowel movement (SBM) within 24 h after the first dose of naldemedine was considered the primary outcome, whereas, the secondary outcomes included weekly changes in SBM frequency and adverse events.

RESULTS

A total of 204 patients were enrolled and 184 completed the 7-day study. The average age of the participants (103 males, 101 females) was 63 ± 14 years. The primary cancer was detected in the lungs (23.5%), gastrointestinal tract (13.7%), and urological organs (9.3%). A considerable proportion of patients (34.8%) had ECOG performance status of 3-4. Most patients were undergoing active cancer treatment, however, 40.7% of the patients were receiving the best supportive care. Within 24 h of the first naldemedine dose, 146 patients (71.6%, 95% CI: 65.4-77.8%) experienced SBMs. The weekly SBM counts increased in 62.7% of the participants. The major adverse events included diarrhea and abdominal pain, detected in 17.6% and 5.4% of the patients, respectively. However, no serious adverse events were observed.

CONCLUSION

Conclusively, naldemedine is effective and safe for OIC treatments in real-world palliative care settings.

TRIAL REGISTRATION NUMBER

UMIN000031381, registered 20/02/2018.

Prevalence and Risk Factors of Constipation Symptoms among Patients Undergoing Colonoscopy: A Single-Center Cross-Sectional Study

INTRODUCTION

Constipation is one of the most common gastrointestinal symptoms. It may compromise quality of life and social functioning and result in increased healthcare use and costs. We aimed to evaluate the prevalence and risk factors of constipation symptoms, as well as those of refractory constipation symptoms among patients who underwent colonoscopy.

METHODS

Over 4.5 years, patients who underwent colonoscopy and completed questionnaires were analyzed. Patients' symptoms were evaluated using the Gastrointestinal Symptoms Rating Scale.

RESULTS

Among 8,621 eligible patients, the prevalence of constipation symptoms was 33.3%. Multivariate analysis revealed female sex (odds ratio [OR] 1.7, p < 0.001), older age (OR 1.3, p < 0.001), cerebral stroke with paralysis (OR 1.7, p = 0.009), chronic renal failure (OR 2.6, p < 0.001), ischemic heart disease (OR 1.3, p = 0.008), diabetes (OR 1.4, p < 0.001), chronic obstructive pulmonary disease (OR 1.5, p = 0.002), benzodiazepine use (OR 1.7, p < 0.001), antiparkinsonian medications use (OR 1.9, p = 0.030), and opioid use (OR 2.1, p = 0.002) as independent risk factors for constipation symptoms. The number of patients taking any medication for constipation was 1,134 (13.2%); however, refractory symptoms of constipation were still present in 61.4% of these patients. Diabetes (OR 1.5, p = 0.028) and irritable bowel syndrome (OR 3.1, p < 0.001) were identified as predictors for refractory constipation symptoms.

CONCLUSIONS

Constipation occurred in one-third of patients, and more than half of patients still exhibited refractory symptoms of constipation despite taking laxatives. Multiple medications and concurrent diseases seem to be associated with constipation symptoms.

The μ-opioid receptor-mediated Gi/o protein and β-arrestin2 signaling pathways both contribute to morphine-induced side effects

The μ-opioid receptor-biased agonist theory holds that Gio protein signaling mediates the analgesic effect of opioids and the related side effects via the β-arrestin2 signaling pathway. A series of μ-opioid-biased agonists have been developed in accordance with this theory, and the FDA has approved TRV130 (as a representative of biased agonists) for marketing. However, several reports have raised the issue of opioid side effects associated with the use of agonists. In this study, five permeable peptides were designed to emulate 11 S/T phosphorylation sites at the μ-opioid receptor (MOR) carboxyl-terminal. In vitro experiments were performed to detect the activation level of G proteins from the cAMP inhibition assay and the β-arrestin2 recruitment by the BRET assay. Designed peptides might effectively interfere with the activation of the Gio and β-arrestin2 pathways when combined with morphine. The resulting morphine-induced tolerance, respiratory inhibition, and constipation in mice showed that the β-arrestin2 pathway was responsible for morphine tolerance while the Gio signaling pathway was involved with respiratory depression and constipation and that these side effects were significantly related to phosphorylation sites S363 and T370. This study may provide new directions for the development of safer and more effective opioid analgesics, and the designed peptides may be an effective tool for exploring the mechanism by which μ-opioid receptors function, with the potential of reducing the side effects that are associated with clinical opioid treatment.

Total postoperative opioid dose is an independent risk factor for prolonged postoperative ileus after laparoscopic colorectal surgery: a case-control study

BACKGROUND

Prolonged postoperative ileus (PPOI) is a major complication of colorectal surgery. Increased opioid consumption has been proposed to increase the risk of PPOI. This study aimed to test the hypothesis that an increased total postoperative opioid dose (TPOD) is associated with the increased incidence of PPOI.

METHODS

For this matched case-control study, patients who underwent elective laparoscopic colorectal procedures at the Peking University People's Hospital between January 2018 and June 2020 were retrospectively reviewed. Patients with PPOI were assigned to the ileus group, while patients without PPOI (control group) were matched at a 1:1 ratio to the ileus group according to age, American Society of Anesthesiologists physical status score, and type of surgical procedure. The primary outcome was the TPOD between the ileus and control groups. The secondary outcome was risk factors of PPOI.

RESULTS

A total of 267 participants were included in the final analysis. No differences in baseline or operative factors were found between the two groups. The TPOD, intravenous sufentanil dose on postoperative day 1 (POD1), and the use of patient-controlled analgesia with basal infusion were associated with PPOI (P < 0.05). Multivariate logistic regression analysis revealed that an increased TPOD was an independent risk factor for developing PPOI after laparoscopic colorectal procedures (Odd ratio: 1.67, 95% CI [1.03, 2.71], P = 0.04).

CONCLUSIONS

The TPOD is an independent risk factor for PPOI after laparoscopic colorectal surgery. We need to explore new strategies of postoperative analgesia to reduce the dosage of TPOD.

Opioid trail: Tracking contributions to opioid use disorder from host genetics to the gut microbiome

Opioid use disorder (OUD) is a worldwide public health crisis with few effective treatment options. Traditional genetics and neuroscience approaches have provided knowledge about biological mechanisms that contribute to OUD-related phenotypes, but the complexity and magnitude of effects in the brain and body remain poorly understood. The gut-brain axis has emerged as a promising target for future therapeutics for several psychiatric conditions, so characterizing the relationship between host genetics and the gut microbiome in the context of OUD will be essential for development of novel treatments. In this review, we describe evidence that interactions between host genetics, the gut microbiome, and immune signaling likely play a key role in mediating opioid-related phenotypes. Studies in humans and model organisms consistently demonstrated that genetic background is a major determinant of gut microbiome composition. Furthermore, the gut microbiome is susceptible to environmental influences such as opioid exposure. Additional work focused on gene by microbiome interactions will be necessary to gain improved understanding of their effects on OUD-related behaviors.

A Novel Bifunctional μOR Agonist and σ1R Antagonist with Potent Analgesic Responses and Reduced Adverse Effects

Bifunctional ligands possessing both μOR agonism and σ1R antagonism have shown promise in producing strong analgesic effects with reduced opioid-related side effects. However, the μOR agonism activity of most dual ligands diminishes compared with classical opioids, raising concern about their effectiveness in managing nociceptive pain. In this study, a new class of dual μOR agonist/σ1R antagonist was reported. Through structure-activity relationship analyses, we identified the optimal compound, 4x, which displayed picomolar μOR agonism activity (EC50: 0.6 ± 0.2 nM) and good σ1R inhibitory activity (Ki: 363.7 ± 5.6 nM) with excellent selectivity. Compound 4x exhibited robust analgesic effects in various pain models, with significantly reduced side effects. Importantly, compound 4x also possessed good safety profiles and no abnormalities were observed in biological parameters even under a high dosage. Our findings suggest that 4x may be a promising lead compound for developing safer opioids and warrants further in-depth studies.

Insights into the Current and Possible Future Use of Opioid Antagonists in Relation to Opioid-Induced Constipation and Dysbiosis

Opioid receptor agonists, particularly those that activate µ-opioid receptors (MORs), are essential analgesic agents for acute or chronic mild to severe pain treatment. However, their use has raised concerns including, among others, intestinal dysbiosis. In addition, growing data on constipation-evoked intestinal dysbiosis have been reported. Opioid-induced constipation (OIC) creates an obstacle to continuing treatment with opioid analgesics. When non-opioid therapies fail to overcome the OIC, opioid antagonists with peripheral, fast first-pass metabolism, and gastrointestinal localized effects remain the drug of choice for OIC, which are discussed here. At first glance, their use seems to only be restricted to constipation, however, recent data on OIC-related dysbiosis and its contribution to the appearance of several opioid side effects has garnered a great of attention from researchers. Peripheral MORs have also been considered as a future target for opioid analgesics with limited central side effects. The properties of MOR antagonists counteracting OIC, and with limited influence on central and possibly peripheral MOR-mediated antinociception, will be highlighted. A new concept is also proposed for developing gut-selective MOR antagonists to treat or restore OIC while keeping peripheral antinociception unaffected. The impact of opioid antagonists on OIC in relation to changes in the gut microbiome is included.

Iatrogenic Side Effects of Pain Therapies

Pain regimens, particularly for chronic cancer and noncancer pain, must balance the important analgesic benefits against potential risks. Many effective and frequently used pain control regimens are associated with iatrogenic adverse events. Interventional procedures can be associated with nerve injuries, vascular injuries, trauma to the spinal cord, and epidural abscesses. Although rare, these adverse events are potentially catastrophic. Pharmacologic remedies for pain must also consider potential side effects that can occur even at therapeutic doses of over-the-counter remedies such as paracetamol (acetaminophen) or nonsteroidal anti-inflammatory drugs. Opioids are effective pain relievers but are associated with many side effects, some of which can be treatment limiting. A prevalent and distressing side effect of opioid therapy is constipation. Opioid-induced constipation is caused by binding to opioid receptors in the gastrointestinal system, making conventional laxatives ineffective. Peripherally acting mu-opioid receptor antagonists are a new drug class that offers the benefits of preserving opioid analgesia without side effects in the gastrointestinal system. An important safety concern, particularly among geriatric patients is the increasingly prevalent condition of polypharmacy. Many senior patients take five or more medications, including some that may be contraindicated in geriatric patients, duplicative of other drugs, have potential pharmacokinetic drug-drug interactions, or may not be the optimal choice for the patient's age and condition. Careful assessment of medications in the elderly, including possibly deprescribing with tapering of certain drugs, may be warranted but should be done systematically and under clinical supervision.

Efficacy and Safety of Naloxegol in Patients with Chronic Non-Cancer Pain Who Experience Opioid-Induced Constipation: A Pooled Analysis of Two Global, Randomized Controlled Studies

Objective

This study evaluates the onset, magnitude, and consistency of improvement of opioid-induced constipation (OIC) symptoms with naloxegol treatment.

Methods

This was a pooled analysis of two Phase 3, double-blind, randomized, placebo-controlled studies (KODIAC-04/05, NCT01309841/NCT01323790) in patients with chronic non-cancer pain and OIC treated with naloxegol 25mg or 12.5mg daily. This analysis assessed improvements in response rates, frequency of spontaneous bowel movement (SBM) and complete SBMs (CSBM), OIC constipation symptoms (straining, stool consistency), time to first post-dose SBM and CSBM, and onset of adverse events over the 12-week period.

Subjects

The population of 1337 subjects had a mean age of 52 years and mean duration of opioid use of 3.6 years at baseline. Mean SBM frequency was 1.4/week.

Results

Naloxegol 25mg and 12.5mg demonstrated significantly higher response rates vs placebo (PBO) [41.9% (P < 0.001), 37.8% (P = 0.008), 29.4% respectively]. Rapid (within 1 week) and sustained (over 12 weeks) symptom improvement was significantly greater for naloxegol vs PBO (P < 0.05). Both doses showed statistically significant and clinically meaningful improvements in straining, stool consistency, number of SBMs and CSBMs/wk. Significantly shorter times to first post-dose SBM and CSBM were observed with naloxegol vs PBO (SBM HR: 25mg = 1.90, 12.5mg= 1.60; CSBM HR: 25mg = 1.42, 12.5mg = 1.36; P < 0.001 for each regimen). Adverse events occurred more frequently in the naloxegol 25mg group and were most frequently reported during the first week.

Conclusion

In patients with chronic non-cancer pain, naloxegol 25mg and 12.5mg demonstrated significantly higher response rates and rapid and sustained improvements in OIC symptoms compared with PBO.

Morphine use induces gastric microbial dysbiosis driving gastric inflammation through TLR2 signalling which is attenuated by proton pump inhibition

BACKGROUND AND PURPOSE

Opioids are the standard drug for pain management; however, their effects on gastric dysfunction are relatively understudied. Opioid users have a higher incidence of gastric pathology leading to increased hospitalization. Herein, we investigated the consequences of morphine use on gastric pathology and the underlying mechanisms. We further investigated the therapeutic benefit of proton pump inhibition to overcome morphine-mediated gastric inflammation.

EXPERIMENTAL APPROACH

Mice were implanted with 25 mg slow-release morphine and placebo pellets. Gastric microbiome analyses were performed. Gastric damage was assayed. Gastric pH was measured. Germ-free and TLR2KO mice were used to investigate the mechanisms. Gastroprotective studies were performed with the proton pump inhibitor (PPI) omeprazole.

KEY RESULTS

Chronic morphine treatment alters gastric microbial composition and induces preferential expansion of pathogenic bacterial communities such as Streptococcus and Pseudomonas. Morphine causes disruption of the gastric mucosal layer, increases apoptosis, and elevates inflammatory cytokines. Moreover, morphine-mediated gastric pathology was significantly attenuated in germ-free mice, and reconstitution of morphine gastric microbiome in germ-free mice resulted gastric inflammation. In addition, morphine-mediated gastric inflammation was attenuated in TLR2KO mice. Morphine causes a decrease in gastric pH, which contributes to gastric dysbiosis leads to gastric inflammation. Omeprazole treatment inhibits gastric acidity, rescuing morphine-induced gastric dysbiosis and preventing inflammation.

CONCLUSION AND IMPLICATIONS

This study attributes morphine-induced gastric acidity as a driver of gastric dysbiosis and pathology and proposes the therapeutic use of PPI as an inexpensive approach for the clinical management of morphine-associated pathophysiology.

Effects of Electroacupuncture for Opioid-Induced Constipation in Patients With Cancer in China: A Randomized Clinical Trial

IMPORTANCE

Opioid-induced constipation (OIC) is prevalent among patients treated with opioids for cancer pain. Safe and effective therapies for OIC in patients with cancer remain an unmet need.

OBJECTIVE

To determine the efficacy of electroacupuncture (EA) for OIC in patients with cancer.

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial was conducted at 6 tertiary hospitals in China among 100 adult patients with cancer who were screened for OIC and enrolled between May 1, 2019, and December 11, 2021.

INTERVENTIONS

Patients were randomized to receive 24 sessions of EA or sham electroacupuncture (SA) over 8 weeks and then were followed up for 8 weeks after treatment.

MAIN OUTCOMES AND MEASURES

The primary outcome was the proportion of overall responders, defined as patients who had at least 3 spontaneous bowel movements (SBMs) per week and an increase of at least 1 SBM from baseline in the same week for at least 6 of the 8 weeks of the treatment period. All statistical analyses were based on the intention-to-treat principle.

RESULTS

A total of 100 patients (mean [SD] age, 64.4 [10.5] years; 56 men [56.0%]) underwent randomization; 50 were randomly assigned to each group. Among them, 44 of 50 patients (88.0%) in the EA group and 42 of 50 patients (84.0%) in the SA group received at least 20 (≥83.3%) sessions of treatment. The proportion of overall responders at week 8 was 40.1% (95% CI, 26.1%-54.1%) in the EA group and 9.0% (95% CI, 0.5%-17.4%) in the SA group (difference between groups, 31.1 percentage points [95% CI, 14.8-47.6 percentage points]; P < .001). Compared with SA, EA provided greater relief for most OIC symptoms and improved quality of life among patients with OIC. Electroacupuncture had no effects on cancer pain and its opioid treatment dosage. Electroacupuncture-related adverse events were rare, and, if any, all were mild and transient.

CONCLUSIONS AND RELEVANCE

This randomized clinical trial found that 8-week EA treatment could increase weekly SBMs with a good safety profile and improve quality of life for the treatment of OIC. Electroacupuncture thus provided an alternative option for OIC in adult patients with cancer.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03797586.

A Retrospective Observational Study of Factors Affecting the Efficacy of Concurrent Prescription of Naldemedine for Opioid-Induced Constipation Caused by Oxycodone Tablets

Naldemedine is indicated for the treatment of opioid-induced constipation (OIC), but reports on its efficacy in preventing OIC are few. Therefore, we retrospectively investigated factors affecting the efficacy of concurrent prescription of naldemedine on OIC. Outpatients with cancer who were started on oxycodone 10 mg/d were included in the study. The eligible patients were classified by their physicians into the following three groups: Group A used regular laxatives before the introduction of oxycodone and initiated naldemedine treatment simultaneously with oxycodone administration, Group B did not take laxatives before the introduction of oxycodone and started naldemedine simultaneously with oxycodone administration, and Group C had been administering regular laxatives before the introduction of oxycodone and were not prescribed naldemedine simultaneously with oxycodone treatment. The Support Team Assessment Schedule Japanese edition score for constipation, frequency of defecation, Bristol Stool Form Scale, sense of incomplete rectal evacuation, and development or worsening of straining to pass bowel movements were compared among the three groups before and after oxycodone administration. In Group B, there was significant worsening of the four parameters except for the sense of incomplete rectal evacuation, whereas Groups A and C did not present any changes. In logistic regression analysis, body weight ≥51.8 kg was a factor significantly decreasing the preventive effect of naldemedine on OIC, and regular use of laxatives was a factor significantly increasing the preventive effect of naldemedine on OIC. Thus, the initiation of naldemedine should be considered depending on the body weight and regular laxative use.

Perceived Provision of Perioperative Information and Care by Patients Who Have Undergone Surgery for Colorectal Cancer: A Cross-Sectional Study

BACKGROUND

Active patient participation in preparation and recovery from colorectal cancer surgery can be facilitated by timely information and care and may improve patient wellbeing and reduce hospitalizations; Methods: We aimed to identify gaps in perioperative information and care by asking colorectal cancer surgical patients to retrospectively report on their perceptions of care via a cross-sectional survey; Results: Overall, 179 (64% consent rate) patients completed one of two 64-item surveys exploring their views of 'optimal care' or their experiences of 'actual care'. In total, 41 (64%) aspects of care were endorsed as optimal. Of these, almost three-quarters (73%) were received by most patients (80% or more). Gaps in care were identified from discrepancies in the endorsement of optimal versus actual survey items. Of the 41 items identified as representing 'optimal care', 11 items were received by fewer than 80% of patients, including the provision of information about the impact of surgical wait-times on cancer cure (69%); pre-habilitation behaviors to improve health (75%); the type of questions to ask the health care team (74%); impact of pain medications on bowel movements (73%); how to obtain medical supplies for self-care at home (67%); dietary or exercise advice after discharge (25-31%); and emotional advice after discharge (44%).

CONCLUSIONS

These gaps represent patient-centered priorities and targets for supportive interventions.

Bisacodyl overcomes morphine-induced constipation by decreasing colonic Aquaporin-3 and Aquaporin-4 expression

Introduction: Morphine is an opioid prescribed to treat aches and pains. However, morphine often causes opioid-induced constipation (OIC). Aquaporin (AQP) transporters, especially AQP3 and AQP4, play an essential role in mediating constipation. Bisacodyl is a common laxative used to treat constipation. To date, the effects of bisacodyl on AQP3 and AQP4 expression and the role this interaction plays in constipation are unclear. This study aimed to determine the effects of bisacodyl on AQP3 and AQP4 expression in mice after induction of constipation with morphine.

Materials and methods: The laxative effects of bisacodyl on both acute and chronic morphine-induced constipation were determined. Fecal water content, colonic bead expulsion, and colonic mRNA levels for AQP3 and AQP4 mRNA were measured.

Results and discussion: The administration of morphine to mice resulted in decreased fecal water content, longer bead expulsion times, and increased AQP3 and AQP4 mRNA levels in the colon. Meanwhile, bisacodyl administration prevented the morphine-induced changes in fecal water content, bead expulsion time, and AQP3 and AQP4 mRNA levels in the colons of mice.

Conclusion: This study suggests that bisacodyl may prevent morphine-induced constipation by preventing morphine-induced increases in AQP3 and AQP4 expression in the colon.

Graphical abstract:

Mu-opioid antagonists for opioid-induced bowel dysfunction in people with cancer and people receiving palliative care

BACKGROUND

Opioid-induced bowel dysfunction (OIBD) is characterised by constipation, incomplete evacuation, bloating, and gastric reflux. It is one of the major adverse events (AEs) of treatment for pain in cancer and palliative care, resulting in increased morbidity and reduced quality of life. This review is a partial update of a 2008 review, and critiques as previous update (2018) trials only for people with cancer and people receiving palliative care.

OBJECTIVES

To assess for OIBD in people with cancer and people receiving palliative care the effectiveness and safety of mu-opioid antagonists (MOAs) versus different doses of MOAs, alternative pharmacological/non-pharmacological interventions, placebo, or no treatment.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and Web of Science (December 2021), clinical trial registries and regulatory websites. We sought contact with MOA manufacturers for further data.

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing the effectiveness and safety of MOAs for OIBD in people with cancer and people at a palliative stage irrespective of the type of terminal disease.

DATA COLLECTION AND ANALYSIS

Two review authors assessed risk of bias and extracted data. The appropriateness of combining data from the trials depended upon sufficient homogeneity across trials. Our primary outcomes were laxation response, effect on analgesia, and AEs. We assessed the certainty of evidence using GRADE and created summary of findings tables.

MAIN RESULTS

We included 10 studies (two new trials) randomising in-total 1343 adults with cancer irrespective of stage, or at palliative care stage of any disease. The MOAs were oral naldemedine and naloxone (alone or in combination with oxycodone), and subcutaneous methylnaltrexone. The trials compared MOAs with placebo, MOAs at different doses, or in combination with other drugs. Two trials of naldemedine and three of naloxone with oxycodone were in people with cancer irrespective of disease stage. The trial on naloxone alone was in people with advanced cancer. Four trials on methylnaltrexone were in palliative care where most participants had advanced cancer. All trials were vulnerable to biases; most commonly, blinding of the outcome assessor was not reported.  Oral naldemedine versus placebo Risk (i.e. chance) of spontaneous laxations in the medium term (over two weeks) for naldemedine was over threefold greater risk ratio (RR) 2.00, 95% confidence interval (CI) 1.59 to 2.52, 2 trials, 418 participants, I² = 0%. Number needed to treat for an additional beneficial outcome (NNTB) 3, 95% CI 3 to 4; moderate-certainty evidence). Earlier risk of spontaneous laxations and patient assessment of bowel change was not reported. Very low-certainty evidence showed naldemedine had little to no effect on opioid withdrawal symptoms. There was little to no difference in the risk of serious (non-fatal) AEs (RR 3.34, 95% CI 0.85 to 13.15: low-certainty evidence). Over double the risk of AEs (non-serious) reported with naldemedine (moderate-certainty evidence). Low-dose oral naldemedine versus higher dose Risk of spontaneous laxations was lower for the lower dose (medium term, 0.1 mg versus 0.4 mg: RR 0.69, 95% CI 0.53 to 0.89, 1 trial, 111 participants (low-certainty evidence)). Earlier risk of spontaneous laxations and patient assessment of bowel change not reported. Low-certainty evidence showed little to no difference on opioid withdrawal symptoms (0.1 mg versus 0.4 mg mean difference (MD) -0.30, 95% CI -0.85 to 0.25), and occurrences of serious AEs (0.1 mg versus 0.4 mg RR 0.25, 95% CI 0.03 to 2.17). Low-certainty evidence showed little to no difference on non-serious AEs. Oral naloxone versus placebo Risk of spontaneous laxations and AEs not reported. Little to no difference in pain intensity (very low-certainty evidence). Full data not given. The trial reported that no serious AEs occurred. Oral naloxone + oxycodone versus oxycodone Risk of spontaneous laxations within 24 hours and in the medium term not reported. Low-certainty evidence showed naloxone with oxycodone reduced the risk of opioid withdrawal symptoms. There was little to no difference in the risk of serious (non-fatal) AEs (RR 0.68, 95% CI 0.44 to 1.06), 3 trials, 362 participants, I² = 55%: very low-certainty evidence). There was little to no difference in risk of AEs (low-certainty evidence).  Subcutaneous methylnaltrexone versus placebo Risk of spontaneous laxations within 24 hours with methylnaltrexone was fourfold greater than placebo (RR 2.97, 95% CI 2.13 to 4.13. 2 trials, 287 participants, I² = 31%. NNTB 3, 95% CI 2 to 3; low-certainty evidence). Risk of spontaneous laxations in the medium term was over tenfold greater with methylnaltrexone (RR 8.15, 95% CI 4.76 to 13.95, 2 trials, 305 participants, I² = 47%. NNTB 2, 95% CI 2 to 2; moderate-certainty evidence). Low-certainty evidence showed methylnaltrexone reduced the risk of opioid withdrawal symptoms, and did not increase risk of a serious AE (RR 0.59, 95% CI 0.38 to 0.93. I² = 0%; 2 trials, 364 participants). The risk of AEs was higher for methylnaltrexone (low-certainty evidence). Lower-dose subcutaneous methylnaltrexone versus higher dose There was little to no difference in risk of spontaneous laxations in the medium-term (1 mg versus 5 mg or greater: RR 2.91, 95% CI 0.82 to 10.39; 1 trial, 26 participants very low-certainty evidence), or in patient assessment of improvement in bowel status (RR 0.98, 95% CI 0.71 to 1.35, 1 trial, 102 participants; low-certainty evidence). Medium-term assessment of spontaneous laxations and serious AEs not reported. There was little to no difference in symptoms of opioid withdrawal (MD -0.25, 95% CI -0.84 to 0.34, 1 trial, 102 participants) or occurrence of AEs (low-certainty evidence).

AUTHORS' CONCLUSIONS

This update's findings for naldemedine and naloxone with oxycodone have been strengthened with two new trials, but conclusions have not changed. Moderate-certainty evidence for oral naldemedine on risk of spontaneous laxations and non-serious AEs suggests in people with cancer that naldemedine may improve bowel function over two weeks and increase the risk of AEs. There was low-certainty evidence on serious AEs. Moderate-certainty evidence for methylnaltrexone on spontaneous laxations over two weeks suggests subcutaneous methylnaltrexone may improve bowel function in people receiving palliative care, but certainty of evidence for AEs was low. More trials are needed, more evaluation of AEs, outcomes patients rate as important, and in children.

Opioid Use in Murine Model Results in Severe Gastric Pathology that May Be Attenuated by Proton Pump Inhibition

Opioids are the gold standard for chronic and acute pain management; however, their consequence on gastric function is relatively understudied. Opioid users have a higher incidence of gastric dysfunction, worse quality of life, increased hospitalizations, and increased use of antiemetic and pain modulator medications. The current study shows that morphine treatment in the murine model results in greater disruption of gastric epithelial cell morphology, increased gastric cell apoptosis, elevated inflammatory cytokines, and matrix metallopeptidase-9 secretion. Morphine treatment also increases gastric acid secretion and causes delays in gastric emptying. Moreover, morphine treatment causes an increase in systemic IL-6 level, which plays an important role in morphine-induced delayed gastric emptying and gastric damage. IL-6 knockout mice show a significant level of reduction in morphine-induced gastric delaying, acid retention, and gastric damage. Thus, morphine-mediated gastric damage is a consequence of the accumulation of acid in the stomach due to increased gastric acid secretion and delayed gastric emptying. Treatment with a proton pump inhibitor resulted in a significant reduction in morphine-induced gastric inflammation, gastric delaying, and improved morphine tolerance. Hence, these studies attribute morphine-mediated induction in gastric acidity and inflammatory cytokines as drivers for morphine-associated gastric pathology and show the therapeutic use of proton pump inhibitors as an inexpensive approach for clinical management of morphine-associated pathophysiology and analgesic tolerance.

Effects of Electroacupuncture on Opioid-Induced Constipation in Patients With Cancer: Study Protocol for a Multicenter Randomized Controlled Trial

Background

Opioid-induced constipation (OIC) is one of the most prevalent adverse events associated with cancer patients who receive opioid analgesics for moderate to severe pain. Acupuncture may be an effective treatment for OIC. We designed this trial to assess the efficacy and safety of electroacupuncture for OIC in cancer patients.

Methods

This is a multicenter, sham-controlled, parallel-group, subject- and assessor-blinded randomized trial. A total of 100 cancer patients with OIC will be randomly assigned to either the electroacupuncture group or the sham electroacupuncture group at a ratio of 1:1. Patients in each group will receive a total of 24-session treatment over 8 weeks, three sessions a week and 30 min each session. Thereafter, patients will be followed up for another 8 weeks. The primary outcome will be the proportion of responders, defined as a patient who has ≥3 spontaneous bowel movements (SBMs)/wk and ≥ increase of 1 SBM from baseline simultaneously for at least 6 out of 8 weeks of the treatment period. The secondary outcomes will include the mean weekly SBMs and complete spontaneous bowel movements, the mean Bristol Stool Form Scale score for stool consistency, the mean score for straining of SBM, the total and subscale scores of Patient Assessment of Constipation-Symptom questionnaires, and the total and subscale scores of Patient Assessment of Constipation-Quality of Life questionnaire. Patients' global assessment of treatment effectiveness, patients' expectation toward the effectiveness of acupuncture and safety of acupuncture will also be assessed. All efficacy analyses will be performed in the intention-to-treat population.

Discussion

To improve the adherence to intervention protocols, the majority of the participants will be recruited from an inpatient setting. The results will help to determine the clinical effects and safety of electroacupuncture for the treatment of OIC among patients with cancer.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier: NCT03797586, registered on 4 January 2019, https://clinicaltrials.gov/ct2/show/NCT03797586.

Effectiveness of Naldemedine Compared with Magnesium Oxide in Preventing Opioid-Induced Constipation: A Randomized Controlled Trial

Simple Summary

Opioids are used in cancer pain management, however, their continuous use may not be tolerable owing to adverse effects such as constipation, sleepiness, nausea, and respiratory depression. Opioid-induced constipation reduces the quality of life of patients, and osmotic laxatives are conventionally recommended for preventing opioid-induced constipation. Recently, naldemedine, a peripherally acting μ-opioid receptor antagonist, can be used to safely and effectively treat opioid-induced constipation based on its etiological mechanism, without affecting central analgesia. In this study, we compared the effectiveness of magnesium oxide with that of naldemedine in preventing opioid-induced constipation. Naldemedine significantly prevented deterioration in the quality of defecation (the Japanese Patient Assessment of Constipation Quality of Life and complete spontaneous bowel movement) and reduced gastrointestinal adverse effects, mainly nausea, compared with magnesium oxide during 12-week administration.

Abstract

Opioid-induced constipation (OIC) may occur in patients receiving opioid treatment, decreasing their quality of life (QOL). We compared the effectiveness of magnesium oxide (MgO) with that of naldemedine (NAL) in preventing OIC. This proof-of-concept, randomized controlled trial (registration number UMIN000031891) involved 120 patients with cancer scheduled to receive opioid therapy. The patients were randomly assigned and stratified by age and sex to receive MgO (500 mg, thrice daily) or NAL (0.2 mg, once daily) for 12 weeks. The change in the average Japanese version of Patient Assessment of Constipation QOL (JPAC-QOL) from baseline to 2 weeks was assessed as the primary endpoint. The other endpoints were spontaneous bowel movements (SBMs) and complete SBMs (CSBMs). Deterioration in the mean JPAC-QOL was significantly lower in the NAL group than in the MgO group after 2 weeks. There were fewer adverse events in the NAL group than in the MgO group. Neither significant differences in the change in SBMs between the groups nor serious adverse events/deaths were observed. The CSBM rate was higher in the NAL group than in the MgO group at 2 and 12 weeks. In conclusion, NAL significantly prevented deterioration in constipation-specific QOL and CSBM rate compared with MgO.

The Relationship Between Opioid Use and Healthcare Utilization in Patients With Inflammatory Bowel Disease: A Systematic Review and Meta-Analysis

BACKGROUND

Pain is commonly experienced by patients with inflammatory bowel disease (IBD). Unfortunately, pain management is a challenge in IBD care, as currently available analgesics are associated with adverse events. Our understanding of the impact of opioid use on healthcare utilization among IBD patients remains limited.

METHODS

A systematic search was completed using PubMed, Embase, the Cochrane Library, and Scopus through May of 2020. The exposure of interest was any opioid medication prescribed by a healthcare provider. Outcomes included readmissions rate, hospitalization, hospital length of stay, healthcare costs, emergency department visits, outpatient visits, IBD-related surgeries, and IBD-related medication utilization. Meta-analysis was conducted on study outcomes reported in at least 4 studies using random-effects models to estimate pooled relative risk (RR) and 95% confidence interval (CI).

RESULTS

We identified 1969 articles, of which 30 met inclusion criteria. Meta-analysis showed an association between opioid use and longer length of stay (mean difference, 2.25 days; 95% CI, 1.29-3.22), higher likelihood of prior IBD-related surgery (RR, 1.72; 95% CI, 1.32-2.25), and higher rates of biologic use (RR, 1.38; 95% CI, 1.13-1.68) but no difference in 30-day readmissions (RR, 1.17; 95% CI, 0.86-1.61), immunomodulator use (RR, 1.13; 95% CI, 0.89-1.44), or corticosteroid use (RR, 1.36; 95% CI, 0.88-2.10) in patients with IBD. On systematic review, opioid use was associated with increased hospitalizations, healthcare costs, emergency department visits, outpatient visits, and polypharmacy.

DISCUSSION

Opioids use among patients with IBD is associated with increased healthcare utilization. Nonopioid alternatives are needed to reduce burden on the healthcare system and improve patient outcomes.

Effects of codeine on esophageal peristalsis in humans using high resolution manometry

BACKGROUND AND AIM

Opioid receptors agonists have been demonstrated to impair lower esophageal sphincter (LES) relaxation and induce spastic esophageal dysmotility, but little was known for their impact on distension-induced secondary peristalsis. The aim of the study was to investigate the hypothesis whether acute administration of codeine can influence physiological characteristics of primary and secondary peristalsis in healthy adults.

METHODS

Eighteen healthy volunteers (13 men, mean age 27.5 years, aged 20-43 years) underwent high resolution manometry (HRM) with a catheter containing an injection port in mid-esophagus. Secondary peristalsis was performed with 10 and 20 mL rapid air injections. Two different sessions including acute administration of codeine (60 mg) or the placebo were randomly performed.

RESULTS

Codeine significantly increased 4-s integrated relaxation pressure (IRP-4s) (P = 0.003) and shortened distal latency (DL) (P = 0.003) of primary peristalsis. The IRP-4s of secondary peristalsis was also significantly higher after codeine than the placebo during air injections with 10 mL (P = 0.048) and 20 mL (P = 0.047). Codeine significantly increased the frequency of secondary peristalsis during air injections with 10 mL than the placebo (P = 0.007), but not for air injection with 20 mL (P = 0.305).

CONCLUSIONS

In addition to impair LES relaxation and reduce distal latency of primary peristalsis, codeine impairs LES relaxation of secondary peristalsis and increases secondary peristaltic frequency. Our study supports the notion in human esophagus that the impact of opioids on peristaltic physiology appears to be present in both primary and secondary peristalsis.

Opioid Analgesia and Opioid-Induced Adverse Effects: A Review

Opioids are widely used as therapeutic agents against moderate to severe acute and chronic pain. Still, these classes of analgesic drugs have many potential limitations as they induce analgesic tolerance, addiction and numerous behavioural adverse effects that often result in patient non-compliance. As opium and opioids have been traditionally used as painkillers, the exact mechanisms of their adverse reactions over repeated use are multifactorial and not fully understood. Older adults suffer from cancer and non-cancer chronic pain more than younger adults, due to the physiological changes related to ageing and their reduced metabolic capabilities and thus show an increased number of adverse reactions to opioid drugs. All clinically used opioids are μ-opioid receptor agonists, and the major adverse effects are directly or potentially connected to this receptor. Multifunctional opioid ligands or peripherally restricted opioids may elicit fewer adverse effects, as shown in preclinical studies, but these results need reproducibility from further extensive clinical trials. The current review aims to overview various mechanisms involved in the adverse effects induced by opioids, to provide a better understanding of the underlying pathophysiology and, ultimately, to help develop an effective therapeutic strategy to better manage pain.

Interaction of Opioids with TLR4-Mechanisms and Ramifications

Simple Summary

Recent evidence indicates that opioids can be active at a receptor that is abundantly expressed on innate immune cells as well as cancer cells: the receptor is termed toll-like receptor 4 (TLR4). TLR4 is increasingly recognised as playing key roles in tumour biology and anticancer defences. However, the issue of whether TLR4 mediates some of the effects of opioids on tumour growth and metastasis is entirely unknown. We review existing evidence, mechanisms, and functional consequences of the action of opioids at TLR4. This opens new avenues of research on the role of opioids in cancer.

Abstract

The innate immune receptor toll-like receptor 4 (TLR4) is known as a sensor for the gram-negative bacterial cell wall component lipopolysaccharide (LPS). TLR4 activation leads to a strong pro-inflammatory response in macrophages; however, it is also recognised to play a key role in cancer. Recent studies of the opioid receptor (OR)-independent actions of opioids have identified that TLR4 can respond to opioids. Opioids are reported to weakly activate TLR4, but to significantly inhibit LPS-induced TLR4 activation. The action of opioids at TLR4 is suggested to be non-stereoselective, this is because OR-inactive (+)-isomers of opioids have been shown to activate or to inhibit TLR4 signalling, although there is some controversy in the literature. While some opioids can bind to the lipopolysaccharide (LPS)-binding cleft of the Myeloid Differentiation factor 2 (MD-2) co-receptor, pharmacological characterisation of the inhibition of opioids on LPS activation of TLR4 indicates a noncompetitive mechanism. In addition to a direct interaction at the receptor, opioids affect NF-κB activation downstream of both TLR4 and opioid receptors and modulate TLR4 expression, leading to a range of in vivo outcomes. Here, we review the literature reporting the activity of opioids at TLR4, its proposed mechanism(s), and the complex functional consequences of this interaction.

Opioid-Related Side Effects and Management

The following areas will be discussed in relation to opioid-related side effects and approaches to their management in the cancer patient.

The Guts of the Opioid Crisis

Bidirectional interactions of the gut epithelium with commensal bacteria are critical for maintaining homeostasis within the gut. Chronic opioid exposure perturbs gut homeostasis through a multitude of neuro-immune-epithelial mechanisms, resulting in the development of analgesic tolerance, a major underpinning of the current opioid crisis. Differences in molecular mechanisms of opioid tolerance between the enteric and central pain pathways pose a significant challenge for managing chronic pain without untoward gastrointestinal effects.

Experimental considerations for the assessment of in vivo and in vitro opioid pharmacology

Morphine and other mu-opioid receptor (MOR) agonists remain the mainstay treatment of acute and prolonged pain states worldwide. The major limiting factor for continued use of these current opioids is the high incidence of side effects that result in loss of life and loss of quality of life. The development of novel opioids bereft, or much less potent, at inducing these side effects remains an intensive area of research, with multiple pharmacological strategies being explored. However, as with many G protein-coupled receptors (GPCRs), translation of promising candidates from in vitro characterisation to successful clinical candidates still represents a major challenge and attrition point. This review summarises the preclinical animal models used to evaluate the key opioid-induced behaviours of antinociception, respiratory depression, constipation and opioid-induced hyperalgesia and tolerance. We highlight the influence of distinct variables in the experimental protocols, as well as the potential implications for differences in receptor reserve in each system. Finally, we discuss how methods to assess opioid action in vivo and in vitro relate to each other in the context of bridging the translational gap in opioid drug discovery.

Topical Fixed-Dose Combinations: A Way of Progress for Pain Management?

Pain, a severe public health problem, can affect patient quality of life when inadequately controlled. Considering that pain pathophysiological mechanisms are complex, combining active pharmaceutical ingredients (APIs) with multiple and synergistic mechanisms of action represents a potentially more effective therapeutic approach than conventional monotherapy treatments. In turn, topical drug delivery has clear advantages over other routes of administration, such as high levels of efficacy, better safety profile and great patient compliance. In this context, the combination of two or more APIs in a single dosage form - fixed-dose combination product (FDC) - for topical administration may represent a promising therapeutic option in the field of pain management. Considering the above mentioned, the purpose of this manuscript is to address an overview of some general aspects regarding pain management and FDCs, as well as the regulatory environment that has to be taken into consideration during their development. Special emphasis will be given to fixed-dose combinations for topical administration with analgesic and/or anti-inflammatory activity. Market drivers of the topical FDC currently approved are ultimately pointed out, and new opportunities in pain management highlighted.

An opioid receptor-independent mechanism underlies motility dysfunction and visceral hyperalgesia in opioid-induced bowel dysfunction

Constipation and abdominal pain are commonly encountered in opioid-induced bowel dysfunction (OBD). The underlying mechanisms are incompletely understood, and treatments are not satisfactory. As patients with OBD often have fecal retention, we aimed to determine whether fecal retention plays a pathogenic role in the development of constipation and abdominal pain in OBD, and if so to investigate the mechanisms. A rodent model of OBD was established by daily morphine treatment at 10 mg/kg for 7 days. Bowel movements, colonic muscle contractility, visceromotor response to colorectal distention, and cell excitability of colon-projecting dorsal root ganglion neurons were determined in rats fed with normal pellet food, or with clear liquid diet. Morphine treatment (Mor) reduced fecal outputs starting on day 1, and caused fecal retention afterward. Compared with controls, Mor rats demonstrated suppressed muscle contractility, increased neuronal excitability, and visceral hypersensitivity. Expression of cyclooxygenase-2 (COX-2) and nerve growth factor (NGF) was upregulated in the smooth muscle of the distended colon in Mor rats. However, prevention of fecal retention by feeding rats with clear liquid diet blocked upregulation of COX-2 and NGF, restored muscle contractility, and attenuated visceral hypersensitivity in Mor rats. Moreover, inhibition of COX-2 improved smooth muscle function and fecal outputs, whereas anti-NGF antibody administration attenuated visceral hypersensitivity in Mor rats. Morphine-induced fecal retention is an independent pathogenic factor for motility dysfunction and visceral hypersensitivity in rats with OBD. Liquid diet may have therapeutic potential for OBD by preventing fecal retention-induced mechanotranscription of COX-2 and NGF.NEW & NOTEWORTHY Our preclinical study shows that fecal retention is a pathogenic factor in opioid-induced bowel dysfunction, as prevention of fecal retention with liquid diet improved motility and attenuated visceral hyperalgesia in morphine-treated animals by blocking expression of cyclooxygenase-2 and nerve growth factor in the colon.

Neurogenic Bowel in Acute Rehabilitation Following Spinal Cord Injury: Impact of Laxatives and Opioids

Objective: To explore the association between bowel dysfunction and use of laxatives and opioids in an acute rehabilitation setting following spinal cord injury (SCI). Methods: Data was collected regarding individuals with acute traumatic/non-traumatic SCI over a two-year period (2012–2013) during both the week of admission and discharge of their inpatient stay. Results: An increase in frequency of bowel movement (BM) (p = 0.003) and a decrease in frequency of fecal incontinence (FI) per week (p < 0.001) between admission and discharge was found across all participants. There was a reduction in the number of individuals using laxatives (p = 0.004) as well as the number of unique laxatives taken (p < 0.001) between admission and discharge in our cohort. The number of individuals using opioids and the average dose of opioids in morphine milligram equivalents (MME) from admission to discharge were significantly reduced (p = 0.001 and p = 0.02, respectively). There was a positive correlation between the number of laxatives and frequency of FI at discharge (r = 0.194, p = 0.014), suggesting that an increase in laxative use results in an increased frequency of FI. Finally, there was a significant negative correlation between average dose of opioids (MME) and frequency of BM at discharge, confirming the constipating effect of opioids (r = −0.20, p = 0.009).

Antidiarrheal Effect of Zornia brasiliensis Vogel (Leguminosae) on Mice Involves Adrenergic Pathway Activation

Several secondary metabolites have been isolated from Zornia brasiliensis (Leguminosae), mainly flavonoids. These compounds are known for many pharmacological actions, such as antispasmodic and antidiarrheal. Therefore, we evaluated the antidiarrheal effect of the ethanolic extract obtained from Zornia brasiliensis aerial parts (ZB-EtOH_AP), as well as its underlying mechanisms. Castor-oil-induced diarrhea, fluid accumulation, and intestinal transit (normal and castor oil induced) were performed to assess the antidiarrheal, antisecretory, and antipropulsive activities of the extract. The involvement of opioid and adrenergic pathways was also investigated. ZB-EtOH_AP inhibited, in a dose-dependent manner, both total defecation frequency and the number of watery stools. The extract showed no effect on fluid accumulation or normal intestinal transit. On the other hand, when the animals were pretreated with castor oil, the extract decreased the distance traveled by the marker in the small intestine. Investigation of the involvement of opioid and adrenergic systems showed that the pharmacological potency of the extract did not change in the presence of naloxone, but it was reduced in the presence of yohimbine. The data indicate that Zornia brasiliensis has an antidiarrheal effect due to inhibition of the intestinal motility through adrenergic pathway activation.

Association between rectal douching and HIV acquisition: the mediating role of condom use and rectal bleeding in a national online sample of Chinese men who have sex with men

OBJECTIVES

Previous studies have demonstrated that rectal douching (RD) is associated with HIV acquisition among men who have sex with men (MSM). However, the precise mechanism underlying the association between RD and HIV remains unclear.

METHODS

We recruited participants over WeChat from October 2017 to October 2018. Respondents received mailed HIV self-testing kits, uploaded images of HIV self-test results and completed an online electronic questionnaire simultaneously. The questionnaire assessed sociodemographic characteristics, RD practices and sexual risk behaviours. HIV status was measured as the result of the HIV self-testing. The Baron and Kenny statistical method was used to assess the association between RD and HIV, controlling for condomless anal intercourse (CAI) and rectal bleeding.

RESULTS

Of 1365 participants, 39.93% (545/1365) reported RD in the past 6 months, 60.07% had multiple male sexual partners and 43.08% had CAI in the past 6 months. The prevalence of HIV, based on self-testing, was 3.37% (46/1365). Multivariable logistic analysis showed RD was significantly associated with bottom sexual role (adjusted OR (aOR) 14.0; 95% CI 9.8 to 20.2), having multiple male sexual partners (aOR 1.8; 95% CI 1.4 to 2.2), CAI (aOR 1.3; 95% CI 1.0 to 1.6), rectal bleeding (aOR 2.0; 95% CI 1.6 to 2.6) and HIV infection (aOR 1.9; 95% CI 1.0 to 3.4). Baron and Kenny analysis found both CAI (aOR 2.2; 95% CI 1.2 to 4.1) and rectal bleeding (aOR 1.9; 95% CI 1.0 to 3.4) play a mediating role in the association between RD and HIV.

CONCLUSIONS

Our study results confirmed the relationship between RD and HIV, and found CAI and rectal bleeding mediated HIV infection in Chinese MSM who douched. Strategies should be encouraged to strengthen health education and reduce high-risk sexual behaviour in order to reduce the risk of HIV in MSM who use enemas. Rectal microbicides may represent an efficient means of providing HIV prophylaxis among MSM.

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.

Analgesic effectiveness of Local Infiltrative Analgesia alone versus combined single dose adductor canal block with Local Infiltrative Analgesia: A single centre case control study

BACKGROUND

Both adductor canal block (ACB) and of Local Infiltrative Analgesia (LIA) have been shown to reduce pain after total knee arthroplasty (TKA). The efficacy of combining ACB and LIA remains controversial. The objective of this study is to analyse the effect of LIA + single dose ACB compared to LIA alone on early post-operative pain and mobilization in TKA.

METHODS

This Cohort Prospective study analyses the Visual Analogue Score (VAS) pain scores and rehabilitation milestones at 24 h between LIA alone and LIA + single dose ACB in unilateral TKA operated by a single surgeon between August 2014 and February 2019.

RESULTS

VAS at rest and on movement were significantly better in the combined LIA + ACB group (n = 151) compared to LIA (n = 120) alone at 24 h. All patients were able to achieve the desired milestones of sitting, standing by the bedside and walking with the help of a walker within 24 h of the surgery.

CONCLUSION

Though the VAS scores were statistically significant, the actual scores at rest and on movement in both groups were significantly better than preoperative scores with excellent pain relief. All patients in both groups were able to ambulate within 24 h. LIA alone significantly improved the pain scores and enabled early mobilization. Addition of single dose ACB to LIA did not significantly alter the milestones.

Can adequate analgesia be achieved in patients with cirrhosis without precipitating hepatic encephalopathy? A prospective study

Aim of the study

Analgesic use in patients with liver cirrhosis can be associated with increased morbidity and mortality and presents clinicians with a significant and challenging management issue. We evaluated the efficacy of opiate analgesia in patients with cirrhosis, while closely monitoring the side effect profile.

Material and methods

This prospective cohort pilot study compared inpatients with cirrhosis who required regular opiate analgesia to non-cirrhotic patients requiring opiates and patients with cirrhosis who did not require opiates. Participants completed daily surveys to assess for analgesic efficacy and encephalopathy.

Results

Fifty-two patients were initially recruited, of whom 50 patients were analysed in three groups (40 male, 10 female, median age 52 years). These included 13 cirrhotic patients (69% Child-Pugh B or C) requiring regular opiate analgesia, 18 cirrhotic patients (67% Child-Pugh B or C) not receiving regular opiate analgesia, and 19 non-cirrhotic controls. Two patients were excluded due to past stroke and acquired brain injury. All cirrhotic patients received regular lactulose. There was no statistical difference in the adequacy of analgesia between the three groups. The modified orientation log score for encephalopathy remained in the normal range in all but two cirrhotic patients receiving regular opiate analgesia.

Conclusions

Effective pain control is achievable with opiate analgesia in most patients with advanced liver disease without precipitating hepatic encephalopathy.

Blood-brain barrier: mechanisms governing permeability and interaction with peripherally acting μ-opioid receptor antagonists

The blood-brain barrier (BBB) describes the unique properties of endothelial cells (ECs) that line the central nervous system (CNS) microvasculature. The BBB supports CNS homeostasis via EC-associated transport of ions, nutrients, proteins and waste products between the brain and blood. These transport mechanisms also serve as physiological barriers to pathogens, toxins and xenobiotics to prevent them from contacting neural tissue. The mechanisms that govern BBB permeability pose a challenge to drug design for CNS disorders, including pain, but can be exploited to limit the effects of a drug to the periphery, as in the design of the peripherally acting μ-opioid receptor antagonists (PAMORAs) used to treat opioid-induced constipation. Here, we describe BBB physiology, drug properties that affect BBB penetrance and how data from randomized clinical trials of PAMORAs improve our understanding of BBB permeability.

Comparing the effectiveness of magnesium oxide and naldemedine in preventing opioid-induced constipation: a proof of concept, single institutional, two arm, open-label, phase II, randomized controlled trial: the MAGNET study

Background

Patients taking opioids are known to develop opioid-induced constipation (OIC), which reduces their quality of life. The aim of this study is to compare magnesium oxide with naldemedine and determine which is more effective in preventing OIC.

Methods

This proof-of-concept, prospective, randomized controlled trial commenced in Japan in March 2018. Initially, a questionnaire-based survey will be conducted targeting adult patients with cancer who concomitantly commenced opioid treatment and OIC prevention treatment. Patients will then be randomly allocated to a magnesium oxide group (500 mg thrice daily) or a naldemedine group (0.2 mg once daily). Each drug will be orally administered for 12 weeks. The primary endpoint is defined as any improvement in scores on the Japanese version of Patient Assessment of Constipation Quality of Life questionnaire (JPAC-QOL) from baseline to 2 weeks of treatment.

Discussion

The primary endpoint is change in JPAC-QOL score from baseline to 2 weeks of intervention. The key secondary endpoint will be change in spontaneous bowel movements at 2 and 12 weeks of intervention. This study will determine whether magnesium oxide or naldemedine is more effective for the prevention of OIC.

Trial registration

University Hospital Medical Information Network (UMIN) Clinical Trials Registry, UMIN000031891. Registered March 25, 2018.

Comparative pharmacodynamic, pharmacokinetic and tissue distribution of Dahuang-Gancao decoction in normal and experimental constipation mice

Dahuang-Gancao decoction (DGD) is a classical formula, which is commonly used for reliving constipation in Chinese clinic. The aim of this study was to investigate the pharmacodynamic, pharmacokinetic and tissue distribution alternations of DGD in normal and constipation mice. DGD exhibited stronger purgative effect in constipation mice by the increased fecal excretion and reduced first defection time compared with normal mice. The C_max, AUC_0-t and MRT_0-t of rhein, aloe-emodin, rhein-8-O-β-D-glucoside, sennoside A, and glycyrrhizic acid as main bio-active components in DGD were markedly increased in constipation mice. The tissue distribution of the analytes in constipation mice were higher than those in normal mice with rhein > rhein-8-O-β-D-glucoside > aloe-emodin > glycyrrhizic acid > emodin in liver, and glycyrrhizic acid > rhein-8-O-β-D-glucoside > liquitin > sennoside A > rhein > aloe-emodin > emodin in colon. The kidney concentrations of the analytes showed a descending order of rhein > rhein-8-O-β-D-glucoside > sennoside A > glycyrrhizic acid > aloe-emodin > emodin, most of them were higher while rhein was lower in constipation mice than normal mice. The higher exposure of the anthraquinones in plasma, liver and colon may result in the stronger purgative effect in the constipation mice than normal mice. Rhein is mainly excreted through the kidney, the decreased level of rhein in constipation mice may explain the alleviated side effects. Accumulation of glycyrrhizic acid in colon may related with the moderate property of licorice. These results provided the experimental basis for understanding the therapeutic effects and metabolite profile of DGD.

Efficacy and safety of linaclotide for opioid-induced constipation in patients with chronic noncancer pain syndromes from a phase 2 randomized study

Constipation is the most common adverse event (AE) of opioid therapy. This multicenter, phase 2 study evaluated the efficacy and safety of linaclotide in treating opioid-induced constipation (OIC) in patients with chronic noncancer pain syndromes (NCT02270983). Adults with OIC (<3 spontaneous bowel movements [SBMs]/week) related to chronic noncancer pain were randomized 1:1:1 to receive linaclotide 145 µg, linaclotide 290 µg, or placebo once daily for 8 weeks. The primary endpoint was change from baseline in 8-week SBM frequency rate (SBMs/week). Secondary efficacy endpoints included 6/8-week SBM 3 + 1 responders, time to first SBM, and changes from baseline in 8-week stool consistency, abdominal bloating, and straining. Additional endpoints included treatment satisfaction and adequate relief responders. In total, 254 patients were randomized: 87, 88, and 79 received linaclotide 145 µg, linaclotide 290 µg, and placebo, respectively. The mean changes from baseline in SBMs/week during the treatment period were 2.9 and 3.5 in the linaclotide 145 and 290 µg groups (P < 0.01 for both doses), respectively, vs 1.6 in the placebo group. Diarrhea, the most common AE, was generally mild, resulting in 1.1%, 5.7%, and 1.3% of patients discontinuing in the linaclotide 145 μg, linaclotide 290 μg, and placebo groups, respectively. No serious AEs related to diarrhea were reported in any treatment group. Compared with placebo, linaclotide-treated patients had significant improvements in stool consistency, straining, abdominal bloating, and treatment satisfaction scores (P < 0.05). Linaclotide significantly improved OIC symptoms and was well tolerated in patients with chronic noncancer pain.

Prevalence and Risk Factors for Opioid-Induced Constipation in an Older National Veteran Cohort

Objectives

This research describes the prevalence and covariates associated with opioid-induced constipation (OIC) in an observational cohort study utilizing a national veteran cohort and integrated data from the Center for Medicare and Medicaid Services (CMS).

Methods

A cohort of 152,904 veterans with encounters between 1 January 2008 and 30 November 2010, an exposure to opioids of 30 days or more, and no exposure in the prior year was developed to establish existing conditions and medications at the start of the opioid exposure and determining outcomes through the end of exposure. OIC was identified through additions/changes in laxative prescriptions, all-cause constipation identification through diagnosis, or constipation related procedures in the presence of opioid exposure. The association of time to constipation with opioid use was analyzed using Cox proportional hazard regression adjusted for patient characteristics, concomitant medications, laboratory tests, and comorbidities.

Results

The prevalence of OIC was 12.6%. Twelve positively associated covariates were identified with the largest associations for prior constipation and prevalent laxative (any laxative that continued into the first day of opioid exposure). Among the 17 negatively associated covariates, the largest associations were for erythromycins, androgens/anabolics, and unknown race.

Conclusions

There were several novel covariates found that are seen in the all-cause chronic constipation literature but have not been reported for opioid-induced constipation. Some are modifiable covariates, particularly medication coadministration, which may assist clinicians and researchers in risk stratification efforts when initiating opioid medications. The integration of CMS data supports the robustness of the analysis and may be of interest in the elderly population warranting future examination.

Pharmacological and molecular docking assessment of cryptotanshinone as natural-derived analgesic compound

Medicinal plants from traditional chinese medicine are used increasingly worldwide for their benefits to health and quality of life for the relevant clinical symptoms related to pain. Among them, Salvia miltiorrhiza Bunge is traditionally used in asian countries as antioxidant, anticancer, anti-inflammatory and analgesic agent. In this context, several evidences support the hypothesis that some tanshinones, in particular cryptotanshinone (CRY), extracted from the roots (Danshen) of this plant exhibit analgesic actions. However, it is surprisingly noted that no pharmacological studies have been carried out to explore the possible analgesic action of this compound in terms of modulation of peripheral and/or central pain. Therefore, in the present study, by using peripheral and central pain models of nociception, such as tail flick and hot plate test, the analgesic effect of CRY in mice was evaluated. Successively, by the aim of a computational approach, we have evaluated the interaction mode of this diterpenoid on opioid and cannabinoid system. Finally, CRY was dosed in mice serum by an HPLC method validated according to European Medicines Agency guidelines validation rules. Here, we report that CRY displayed anti-nociceptive activity on both hot plate and tail flick test, with a prominent long-lasting peripheral analgesic effect. These evidences were indirectly confirmed after the daily administration of the tanshinone for 7 and 14 days. In addition, the analgesic effect of CRY was reverted by naloxone and cannabinoid antagonists and amplified by arginine administration. These findings were finally supported by HPLC and docking studies, that revealed a noteworthy presence of CRY on mice serum 1 h after its intraperitoneal administration and a possible interaction of tested compound on μ and k receptors. Taken together, these results provide a new line of evidences showing that CRY can produce analgesia against various phenotypes of nociception with a mechanism that seems to be related to an agonistic activity on opioid system.

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.