Traditional Laxatives Research Articles

Lactitol Alleviates Loperamide-Induced Constipation in Sprague Dawley Rats by Regulating Serotonin, Short-Chain Fatty Acids, and Gut Microbiota.

The objective of this study was to examine the impact of lactitol on constipation caused by loperamide in Sprague Dawley rats, with a particular emphasis on its underlying mechanisms and potential health advantages. The lactitol effectively improved fecal parameters, intestinal tissue structure, and the expression of constipation-related gene expression and proteins. Lactitol alleviated fecal weight and water content altered by loperamide and enhanced gastrointestinal transit. The administration also restored mucosal and muscular layer thickness. Mechanistically, lactitol upregulated the mRNA expression and/or protein levels of mucins (MUC2 and MUC4), occludin, claudin-1, and zonula occludens, indicating improved intestinal barrier function. Lactitol positively regulated the composition of cecal microbiota, leading to an increased relative abundance of Bifidobacterium, Lactobacillus, and Romboutsia. Conversely, lactitol decreased the relative abundance of Prevotella, Aerococcus, Muribaculum, Blautia, and Ruminococcus. This study demonstrated the potential of lactitol to relieve constipation by modulating the gut microbiota. These findings suggest that lactitol is an alternative to traditional laxatives and has potential as a health-promoting food sweetener.

Evaluating the Safety and Efficacy of Naloxegol in Critically Ill Opioid-Induced Constipation Patients.

Background Opioid-induced constipation (OIC) has become more common in the intensive care unit (ICU) due to increased opioid utilization. Traditional laxatives often prove ineffective against OIC, leading to the increased utilization of naloxegol. However, further research is needed to confirm naloxegol's effectiveness and safety in critical care. This study aimed to explore the safety and efficacy of this intervention in critically ill OIC patients. Methods A single-center retrospective study was conducted on 353 patients who received one or more doses of naloxegol from January 1, 2019, to June 30, 2020, for OIC at a tertiary care center. The primary endpoint of this study was to evaluate serious adverse events such as reduced analgesic effect, gastrointestinal perforation, seizure, acute myocardial infarction (AMI), or ventricular arrhythmias using Naranjo Scale in critically ill patients. The secondary goal was to assess the efficacy of naloxegol, measured by the time of the first bowel movement. Results The average duration of naloxegol use was three days, with the first bowel movement occurring at an average of 11.3 hours. Furthermore, 59.8% of individuals had their first bowel movement within 20 hours of receiving naloxegol. There was a low level of causality between naloxegol use and adverse events such as gastrointestinal perforation, seizures, AMI, cardiovascular mortality, stroke, and ventricular arrhythmia. Additionally, reduction in analgesia showed no strong relationship with naloxegol use indicated by the Naranjo Scale assessment. Conclusion Naloxegol showed promising safety and efficacy profiles in treating OIC amongst critically ill patients, though our findings require further validation through prospective studies. This research paves the way for further investigation into naloxegol's role in OIC management, emphasizing the necessity of personalized treatment strategies in critical care settings.

Current Management of Chronic Constipation in Japan.

Constipation is a complicated condition. Chronic constipation is diagnosed when constipation occurs for more than 3 months. Chronic constipation is classified using patient symptoms and the pathophysiology. New therapeutic agents to treat chronic constipation have recently been approved in Japan. However, treatments for constipation that is refractory to traditional laxatives have been approved, an algorithm for the treatment of chronic constipation has not yet been developed. The accumulation of knowledge and data is necessary to develop a new algorithm.

Effects of Prokinetics on the Digestive Tract

Functional gastrointestinal disorders account for at least a third of visits to gastroenterology clinics. Despite pathophysiological complexity, impaired gut motility may be frequently present in these disorders. Prokinetics are a class of drugs that promote gastrointestinal motility, accelerate transit, and potentially improve digestive symptoms. Several prokinetic agents with a great variety of mechanisms of action are available. The purpose of this paper is to update our current knowledge about the efficacy and safety of prokinetics. A literature search on efficacy and safety of prokinetics was carried out using the online databases of Pubmed, Medline, and Cochrane. Based on the action of different receptors, prokinetics mainly comprise dopamine antagonists, 5HT4 agonists, motilin agonists, ghrelin agonists, and cholinergic agonists. Prokinetics have the potential to improve motility function in all segments of the digestive tract, from the esophagus to the colon. In particular, drug international agencies have approved antidopaminergic metoclopramide for the treatment of gastroparesis and serotoninergic prucalopride for chronic constipation not responsive to traditional laxatives. Arrhythmias by QT prolongation and galactorrhea by prolactin stimulation are the more frequent side effects related to prokinetics use. Old and new prokinetics are effective in ameliorating digestive motility disorders and related symptoms and are widely prescribed. Special attention should be paid to the potential adverse events of these agents.

Constipation in Cancer Patients - an Update of Clinical Evidence.

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

Opioid-Induced Constipation in Advanced Cancer Patients.

The present study discusses opioid-induced constipation (OIC) in advanced cancer patients, focusing on the OIC definition, pathophysiology, and treatment. OIC is any change from baseline defecation patterns and bowel habits that developed after starting opioid therapy. The condition is characterized by bowel frequency reduction, worsening or development of straining, a sensation of incomplete defecation, or distress associated with bowel habits. OIC is common in advanced cancer patients, with a prevalence of approximately 51%-87% in patients taking opioids for pain management. Patients are likely to experience severe distress, work productivity reduction, poor quality of life, and increased healthcare utilization. OIC has a complex pathophysiology that involves propulsive and peristalsis impairment, intestinal mucosal secretion inhibition, intestinal fluid absorption enhancement, and anal sphincters function impairment. The Rome III criteria are used to assess and diagnose clinical OIC and can also be diagnosed through the Patient Assessment of Constipation (PAC) measures, including the symptom survey (PAC-SYM) and quality of life survey (PAC-QOL). Non-pharmacological treatment of OIC involves lifestyle habits and dietary adjustments, although these interventions might be insufficient to manage the condition. Pharmacological treatments involve the use of traditional laxatives and newer agents like peripherally acting mu-opioid receptor agonists (PAMORAs), including naldemedine, naloxegol, and methylnaltrexone. More novel treatments for OIC that target the pathophysiology are still needed and should be studied carefully for safety and efficacy.

The role of naldemedine in the treatment of patients with opioid-induced constipation

Opioid-induced bowel dysfunction (OIBD) and opioid-induced constipation (OIC) significantly decrease patients’ quality of life (QoL), lead to complications and opioid non-compliance resulting in pain exacerbation. Traditional laxatives are first-line preventive and therapeutic measures, although they display limited efficacy and several adverse effects (AE). Non-pharmacology measures, prokinetics, opioid switch, all have little evidence and do not target OIBD and OIC pathophysiology both associated with activation of predominantly μ-opioid receptors mostly peripherally in the gastrointestinal (GI) tract. A combination of prolonged-release (PR) oxycodone with PR naloxone in one tablet with a ratio of 2:1 is available, although limitations include maximal daily dose of 160 mg/80 mg, respectively, and normal liver function. Peripherally acting μ-opioid receptor antagonists (PAMORA) block opioid receptors in the GI tract without compromising analgesia as they do not cross the blood–brain barrier. Currently three drugs are available: methylnaltrexone, naloxegol and naldemedine. Naldemedine has proven efficacy superior to placebo in the treatment of OIC in both cancer and non-cancer patients while improving patient-reported constipation symptoms and patients’ QoL. It is well tolerated with mostly mild to moderate intensity GI adverse effects such as abdominal, pain, nausea, and diarrhea, without compromising analgesia. Naldemedine dosing is convenient as it is administered once daily by an oral route. Moreover, naldemedine may be safely used in patients with renal failure and mild to moderate hepatic impairment. Effective prevention and treatment of OIC is of paramount importance in patients receiving long-term opioid therapy. Palliat Med Pract 2019; 13, 3: 113–128

Update on Pharmacotherapy for Irritable Bowel Syndrome.

Irritable bowel syndrome (IBS) is a functional GI disorder that affects a large percentage of the population and presents a significant socio-economic burden on the society. In this article, we reviewed the evidence supporting various pharmacological treatment options for IBS. Rifaximin, eluxadoline, and alosetron have demonstrated that they reduce symptom severity improving quality of life in patients with IBS-diarrhea. Ramosetron is a promising agent in development. Peppermint oil has also demonstrated a positive impact on some symptoms of IBS. For IBS with constipation, traditional laxatives have failed to demonstrate significant benefit. However, lubiprostone, linaclotide, and plecanatide have demonstrated improvement of IBS with constipation in large, placebo-controlled trials. Tenapanor, a sodium/hydrogen exchanger 3 inhibitor, appears to be a promising treatment option in the pipeline. There are multiple pharmacologic agents with a variety of mechanisms that have demonstrated efficacy in IBS with diarrhea and constipation. There are no established pharmacologic agents for IBS with a mixed bowel pattern. There is a promising pipeline for additional novel therapies for IBS.

Methylnaltrexone: Peripherally Acting μ-Opioid Receptor Antagonist

Opioid-induced constipation (OIC) is a common adverse effect associated with opioid therapy, with many patients never developing tolerance to this effect. There are many traditional laxatives available to help patients combat this symptom, yet OIC may not reliably respond to conventional treatment. Peripherally acting µ-opioid receptor antagonists (PAMORAs) have a place in the treatment of refractory OIC, when traditional laxatives have not resulted in effective laxation. There are a number of PAMORAs now available, and methylnaltrexone is the only PAMORA indicated for the treatment of OIC in adults with advanced illness, as well as for patients with chronic noncancer pain, including patients with chronic pain related to prior cancer treatment who do not require frequent opioid escalation. Advanced practitioners need to have an understanding of how and when to best use these medications for the different indications in patients with advanced illness or chronic noncancer-related pain.

Mechanisms underlying effects of kiwifruit on intestinal function shown by MRI in healthy volunteers.

SummaryBackgroundChronic constipation affects approximately 17% of the population worldwide and remains an important unmet need since patients are often dissatisfied with treatment. Kiwifruit may offer an alternative to traditional laxatives and have been shown to increase stool volume, frequency and improve consistency.AimsUsing non‐invasive MRI techniques, we assessed the effect of ingestion of kiwifruit on fluid distribution in the intestines and bowel function.MethodsTwo period crossover trial of kiwifruit vs control in healthy adults. Intervention: two kiwifruits twice daily vs isocaloric control (maltodextrin) twice daily, consumed for a total of 3 days. Subjects underwent MRI scanning fasted and at hourly intervals for 7 hours on the third day. Primary outcome: T1 relaxation time of ascending colon (T1AC) using MRI. Secondary outcomes: Small bowel water content (SBWC), colonic volume, gut transit time, T1 of descending colon, stool frequency and form.ResultsFourteen volunteers completed the study. T1AC was higher after kiwifruit ingestion (P = 0.029) during the second half of the day (when meal residue would be expected to reach the AC, AUC T1 T240‐420 minutes; mean (SD) 137 (39) s*minute with kiwifruit versus 108 (40) s*minute with control. SBWC (P < 0.001), colon volumes (P = 0.004), as well as stool frequency (1.46 ± 0.66 with kiwifruit vs 1.14 ± 0.46 stools per day with control; P = 0.034) and stool form score (Bristol Stool Chart score 4.1 (0.9) with kiwifruit versus 3.4 (0.7) with control; P = 0.011) were markedly increased in participants consuming kiwifruit compared to control.ConclusionConsumption of kiwifruit in healthy volunteers increases water retention in the small bowel and ascending colon and increases total colonic volume. The data may explain the observed increase in stool frequency and looser stool consistencies, suggesting that kiwifruit could be used as a dietary alternative to laxatives in mild constipation.

The role of oxycodone/naloxone in the management of patients with pain and opioid-induced constipation

ABSTRACTIntroduction: Common opioid adverse effects (AE) of the gastrointestinal tract include opioid-induced constipation (OIC) and opioid-induced bowel dysfunction (OIBD) with traditional laxatives being of limited efficacy, having AEs and not addressing the pathophysiology of OIC or OIBD. Targeted treatment comprises of PAMORA (peripherally acting mu-opioid receptor antagonists) and a combination of an opioid receptor agonist with its antagonist, namely prolonged-release oxycodone with prolonged-release naloxone (OXN) tablets at a fixed ratio of 2:1. Oxycodone provides analgesia, whereas naloxone prevents binding or displaces it from opioid receptors located in the gut wall.Areas covered: The authors review the role of OXN in the management of patients with pain and OIC. A literature search was performed using the search terms ‘oxycodone/naloxone’ and ‘opioid-induced constipation’ using the PubMed database up to October 2018.Expert opinion: OXN delivers analgesia comparable (or superior versus placebo and in observational studies) to oxycodone alone and other opioids with a limited or decreased disturbing effect on bowel function. OXN in daily doses of up to 160 mg/80 mg provides effective analgesia with little negative impact on bowel function. OXN may be successfully used in patients with chronic pain, to prevent or treat symptoms of OIC and OIBD.

Recent advances in understanding and managing chronic constipation.

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

Methylnaltrexone bromide for the treatment of opioid-induced constipation

ABSTRACTIntroduction: The extensive and alarming use of opioids for pain management in patients with chronic pain receiving palliative care is associated with non-tolerable gastrointestinal (GI) adverse effects. Opioid-induced constipation (OIC) is the most common adverse effect impairing patient quality of life (QOL). In addition, OIC is one of the treatment limiting consequences of opioid analgesics. Management of OIC is becoming a challenge since traditional laxatives have limited efficiency. Peripherally acting mu-opioid receptor antagonists (PAMORA) have been developed for the treatment of OIC with methylnaltrexone bromide being the first approved to treat OIC in adults with advanced illness undergoing palliative care.Areas covered: The authors systematically review the clinical evidence for methylnaltrexone bromide including a review of the pharmacokinetic and pharmacodynamic data along with clinical effectiveness and cost-effectiveness. Though there is a need for further long-term clinical investigation, there is a large body of evidence for both its efficacy and safety in the treatment of OIC.Expert opinion: Methylnaltrexone has both subcutaneous injection and oral dosage forms available in the market. The lack of more evidence in specific populations such as pregnant women, pediatrics and elderly still remains. The global consumption of methylnaltrexone shows a projection of increased use since its approval worldwide in 2008.

Chronic idiopathic constipation in adults: epidemiology, pathophysiology, diagnosis and clinical management.

Chronic idiopathic constipation (CIC) is one of the most common gastrointestinal disorders, with a global prevalence of 14%. It is commoner in women and its prevalence increases with age. There are three subtypes of CIC: dyssynergic defaecation, slow transit constipation and normal transit constipation, which is the most common subtype. Clinical assessment of the patient with constipation requires careful history taking, in order to identify any red flag symptoms that would necessitate further investigation with colonoscopy to exclude colorectal malignancy. Screening for hypercalcaemia, hypothyroidism and coeliac disease with appropriate blood tests should be considered. A digital rectal examination should be performed to assess for evidence of dyssynergic defaecation. If this is suspected, further investigation with high resolution anorectal manometry should be undertaken. Anorectal biofeedback can be offered to patients with dyssynergic defaecation as a means of correcting the associated impairment of pelvic floor, abdominal wall and rectal functioning. Lifestyle modifications, such as increasing dietary fibre, are the first step in managing other causes of CIC. If patients do not respond to these simple changes, then treatment with osmotic and stimulant laxatives should be trialled. Patients not responding to traditional laxatives should be offered treatment with prosecretory agents such as lubiprostone, linaclotide and plecanatide, or the 5-HT4 receptor agonist prucalopride, where available. If there is no response to pharmacological treatment, surgical intervention can be considered, but it is only suitable for a carefully selected subset of patients with proven slow transit constipation.

391 First Reported Use of Methylnaltrexone to Treat Opioid-Induced Constipation in a Pediatric Burn Patient

Pain in critically ill pediatric burn patients is a complex and challenging issue whose adequate control is further complicated by anticipative fear and anxiety. Undertreated pain increases risk for post-burn PTSD and other psychosocial impairments, so it is aggressively managed with regimens often including high-dose opiates. This often results in Opioid-Induced Constipation (OIC) and first line laxative treatments have high recurrence rates due to the continuous, direct gastrointestinal effects of μ-opioid antagonism. Methylnaltrexone (MLTX), an FDA-approved injectable µ-opioid receptor antagonist, selectively acts on the myenteric plexus to reverse OIC without crossing the blood-brain-barrier to impair systemic analgesia. MLTX is safe and highly efficacious at treating OIC in adult and pediatric oncologic patients with recent data showing great effect in adult burn patients. Here we report the first case of the safe and efficacious reversal of OIC in a critically ill pediatric burn patient who failed standard laxative therapies. A retrospective case review was performed on a pediatric burn patient who was treated with MLTX for OIC in the setting of high-dose intravenous opiates. In our unit, MLTX is reserved for patients who remain without a bowel movement for 3 or more consecutive days on escalating regimens of traditional laxatives, particularly if they have worsening abdominal pain, distension, bladder pressures, or intolerance to enteral feeding. Following approval by a pediatric gastroenterologist and pharmacist, subcutaneous MLTX was administered at a dose of 0.15 mg/kg. Any complications related to drug administration (e.g. new abdominal pain, nausea, or bowel perforation) were tracked for risk analysis. Patient was an 11-year-old female with 18% TBSA partial and full thickness burns to face, trunk, and all four extremities with inhalation injury from a house fire. She was intubated prior to arrival, averaged 114 mg morphine equivalents per day, and stopped responding to first line laxation therapy after 12 days, subsequently going 4 days without laxation. She was given 8 mg MLTX with laxation 19 hours after administration. There were no adverse events associated with MLTX administration. MLTX administered as a single dose of 0.15 mg/kg subcutaneously was safely used to induce laxation in a critically ill pediatric burn patient with no observed adverse effects. To our knowledge, this is the first reported case of treating OIC with MLTX in a pediatric burn patient. Larger studies are indicated to further elucidate the safety and efficacy profile of MLTX in pediatric burn patients. MLTX may be a safe and efficacious treatment for OIC in pediatric burn patients requiring high-dose opiates.

Colonoscopy-Assisted Creation of Antegrade Continent Enema Tract in a Patient With Spina Bifida

Spina bifida is a neural tube defect that affects 33-52/100,000 live births. Bowel incontinence affects 60-70% of all patients, and is a source of significant limitation to social interactions. When first line treatment with traditional laxatives fail, an antegrade continence enema (ACE) tract can help improve quality of life. An 18-year-old woman with spina bifida and hydrocephalus was referred for neurogenic bowel characterized by severe constipation and daily fecal incontinence. She had tried several bowel regimens with inconsistent benefit. Her surgical history was complicated by hydrocephalus requiring 2 ventriculoperitoneal shunts, bladder rupture, and bladder augmentation. After discussion of possible options, she elected to undergo an ACE procedure and was referred to pediatric surgery. A plan was made to try a laparoscopic approach, with colonoscopy rescue procedure planned is this was unsuccessful. On the day of procedure, multiple attempts to gain laparoscopic access through the suprapubic and epigastric routes were unsuccessful due to thick adhesions from past surgeries. Both wounds were closed, and gastroenterology was called to proceed with a colonoscopy-assisted procedure. Colonoscopy was accomplished without difficulty with a cecal intubation time of 7 minutes. Attempts at transillumination in the cecum failed. A spot with good transillumination and good one-to-one colonic indentation was identified in mid-ascending colon. Three T-fasteners were deployed in a triangular fashion under endoscopic visualization to anchor the ascending colon to the abdominal wall. A small cruciate incision was made and a needle was passed into the ascending colon. A guidewire was placed through the needle, and the tract dilated to 11 F. A 10.2 F Chait percutaneous cecostomy catheter was deployed using an introducer over the guidewire and placed under visualization in the ascending colon, creating a tract through which antegrade enema could be administered. Procedure time from scope insertion to withdrawal was 27 minutes. The patient was discharged home the day after the procedure. On telephone follow up, she reported excellent bowel control since the procedure was completed. Our report indicates that colonoscopy-assisted creation of an ACE tract can be accomplished without difficulty when laparoscopy may be difficult due to adhesions, or where the appendix may not accessible for a traditional Mallone ACE procedure.Figure: Chait percutaneous cecostomy tube in colon.

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

Opioids are a mainstay in the treatment of chronic non-cancer pain syndromes, but their analgesic benefits come at a cost as opioid-related constipation occurs in 40-80% of individuals taking chronic opioids. Furthermore, as 10-20% of the population suffers from constipation at baseline, it should be expected that while a proportion of individuals will develop constipation as a direct consequence of opioids (OIC), others will experience it as an exacerbation of their baseline constipation (OEC). Herein, we review the evidence-based data for treatments directed at opioid-related constipation focusing on individuals with non-cancer pain syndromes and provide a template for the development of differentiated treatment algorithms for OIC and OEC. Historical and current treatment protocols recommend traditional laxatives, but these are ineffective in up to 50%, due in part to the heterogeneous pathogenesis of constipation. Therapeutic decisions must be tailored to account for this overlapping pathogenesis. OIC and OEC are distinct entities. As such, additional research and guidelines should address these as different patient populations.

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

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

Effective Constipation Treatment Changes More Than Bowel Frequency: A Systematic Review and Meta-Analysis

Background/AimsThe marketing of newer agents for treatment of constipation and irritable bowel syndrome with constipation (IBS-C) emphasize improvements in abdominal pain. However, it is not clear whether this observation reflects a unique visceral analgesic effect of these agents or is a general feature of effective laxation. We sought to determine the relationship between improvements in bowel frequency and decreases in abdominal pain in clinical trials of patients with constipation or IBS-C.MethodsWe searched “PubMed” and “Embase” databanks for clinical trials in patients with constipation or IBS-C, targeting publications that provided detailed data on bowel movement frequency and pain intensity before and after an intervention. We abstracted the results and performed meta-analytic and meta-regression analyses.ResultsTwenty-seven trials (16 constipation and 11 IBS) met entry criteria. Baseline weekly bowel movement frequency was low with 2.35 (2.07–2.64) with differences between constipation (2.00 [1.62–2.38]) and IBS-C (2.77 [2.40–3.14]; Q = 8.18; P = 0.002). Studies reported moderate pain levels (2.12 [1.81–2.42]) with comparable baseline levels in constipation (2.02 [1.63–2.42]) and IBS-C (2.35 [2.10–2.60]; Q = 1.92; P = 0.167). Treatments increased bowel frequency by 2.17 [1.88–2.47] and lowered pain ratings by 0.58 [0.49–0.68]. Meta-regression demonstrated a significant correlation between treatment-induced increases in bowel frequency and decreased pain ratings.ConclusionsOur analysis suggests that reduction of abdominal pain observed in clinical trials of constipation and IBS-C is associated with laxation, and may not require specific drug mechanisms, thus arguing against a unique advantage of newer agents over traditional laxatives in the treatment of constipation and IBS-C.

Emerging therapies for patients with symptoms of opioid-induced bowel dysfunction.

Opioid-induced bowel dysfunction (OIBD) comprises gastrointestinal (GI) symptoms, including dry mouth, nausea, vomiting, gastric stasis, bloating, abdominal pain, and opioid-induced constipation, which significantly impair patients’ quality of life and may lead to undertreatment of pain. Traditional laxatives are often prescribed for OIBD symptoms, although they display limited efficacy and exert adverse effects. Other strategies include prokinetics and change of opioids or their administration route. However, these approaches do not address underlying causes of OIBD associated with opioid effects on mostly peripheral opioid receptors located in the GI tract. Targeted management of OIBD comprises purely peripherally acting opioid receptor antagonists and a combination of opioid receptor agonist and antagonist. Methylnaltrexone induces laxation in 50%–60% of patients with advanced diseases and OIBD who do not respond to traditional oral laxatives without inducing opioid withdrawal symptoms with similar response (45%–50%) after an oral administration of naloxegol. A combination of prolonged-release oxycodone with prolonged-release naloxone (OXN) in one tablet (a ratio of 2:1) provides analgesia with limited negative effect on the bowel function, as oxycodone displays high oral bioavailability and naloxone demonstrates local antagonist effect on opioid receptors in the GI tract and is totally inactivated in the liver. OXN in daily doses of up to 80 mg/40 mg provides equally effective analgesia with improved bowel function compared to oxycodone administered alone in patients with chronic non-malignant and cancer-related pain. OIBD is a common complication of long-term opioid therapy and may lead to quality of life deterioration and undertreatment of pain. Thus, a complex assessment and management that addresses underlying causes and patomechanisms of OIBD is recommended. Newer strategies comprise methylnaltrexone or OXN administration in the management of OIBD, and OXN may be also considered as a preventive measure of OIBD development in patients who require opioid administration.