Systematic review: the management of chronic diarrhoea due to bile acid malabsorption

Advances in the pathophysiology, diagnosis and management of chronic diarrhoea from bile acid malabsorption: a systematic review

Bile acid malabsorption (BAM) is an important disorder of digestive pathophysiology as it generates chronic diarrhoea. This condition originates from intricate pathways involving bile acid synthesis and metabolism in the liver and gut, the composition of gut microbiota, enterohepatic circulation and key receptors as farnesoid X receptor (FXR), fibroblast growth factor receptor 4 (FGFR4), and the G-protein bile acid receptor-1 (GPBAR-1). Although symptoms can resemble those related to disorders of gut brain interaction, accurate diagnosis of BAM may greatly benefit the patient. The empiric diagnosis of BAM is primarily based on the clinical response to bile acid sequestrants. Specific tests including the 48-hour fecal bile acid test, serum levels of 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19), and the 75Selenium HomotauroCholic Acid Test (SeHCAT) are not widely available. Nevertheless, lack of diagnostic standardization of BAM may account for poor recognition and delayed management. Beyond bile acid sequestrants, therapeutic approaches include the use of FXR agonists, FGF19 analogues, glucagon-like peptide-1 (GLP-1) receptor agonists, and microbiota modulation. These novel agents can best make their foray into the therapeutic armamentarium if BAM does not remain a diagnosis of exclusion. Ignoring BAM as a specific condition may continue to contribute to increased healthcare costs and reduced quality of life. Here, we aim to provide a comprehensive review of the pathophysiology, diagnosis, and management of BAM.

Review article: A practical approach to persistent gastrointestinal symptoms in inflammatory bowel disease in remission

BACKGROUND

Persistent gastrointestinal symptoms are prevalent in adult patients with inflammatory bowel disease (IBD), even when endoscopic remission is reached. These symptoms can have profound negative effects on the quality of life of affected patients and can be difficult to treat. They may be caused by IBD-related complications or comorbid disorders, but they can also be explained by irritable bowel syndrome (IBS)-like symptoms.

AIMS

To provide a practical step-by-step guide to diagnose and treat persistent gastrointestinal symptoms in patients with IBD in remission via a personalised approach.

METHODS

We scrutinised relevant literature on causes, diagnostics and treatment of persistent gastrointestinal symptoms (abdominal pain or discomfort, bloating, abdominal distension, diarrhoea, constipation and faecal incontinence) in patients with IBD in remission.

RESULTS

A graphical practical guide for several steps in diagnosing, identifying potential triggers and adequate treatment of persistent gastrointestinal symptoms in IBD in remission is provided based on supporting literature. The first part of this review focuses on the diagnostic and treatment approaches for potential IBD-related complications and comorbidities. The second part describes the approach to IBS-like symptoms in IBD in remission.

CONCLUSIONS

Persistent gastrointestinal symptoms in IBD in remission can be traced back to potential pathophysiological mechanisms in individual patients and can be treated adequately. For both IBD-related complications and comorbidities and IBS-like symptoms in IBD in remission, pharmacological, dietary, lifestyle or psychological treatments can be effective. A systematic and personalised approach is required to reduce the burden for patients, healthcare systems, and society.

Bile Acid Diarrhea Is Associated With an Increased Incidence of Gastrointestinal Cancers

INTRODUCTION

Bile acid diarrhea (BAD) is an underrecognized and socially debilitating disease caused by high concentrations of bile acids in the colon. Bile acids directly and indirectly promote carcinogenesis. In this article, we investigated whether individuals with BAD have an increased risk of gastrointestinal (GI) cancers.

METHODS

By using the Danish health registries, adult individuals with BAD were identified by International Classification of Diseases 10th revision code K90.8 or referral to the diagnostic ⁷⁵selenium-homotaurocholic acid test followed by prescription of a bile acid sequestrant within 365 days (n = 5,245). Age- and sex-matched individuals without BAD were included for comparison (n = 52,450). We analyzed the cumulative incidence of GI cancers after BAD diagnosis and the odds ratios (ORs) of GI cancer 8 and 15 years before BAD diagnosis/matching.

RESULTS

Cumulative incidence of GI cancer 6 years after BAD diagnosis/matching was 1.6% in the BAD group and 1.1% in controls ( P = 0.01). The ORs of total GI cancer 8 and 15 years before BAD diagnosis were 6.16 (5.08-7.48) and 5.19 (4.28-6.29), respectively. Furthermore, 47 individuals with BAD (0.9%) and 250 (0.5%) controls died of GI cancer.

DISCUSSION

This nationwide cohort study indicates an association between BAD and GI cancers. We found both a higher incidence of GI cancer after BAD diagnosis compared with controls and increased OR of GI cancer before BAD diagnosis. Bearing in mind the underdiagnosis of BAD, the delay of BAD diagnosis, and the carcinogenic effect of bile acids, these findings warrant further investigations of the risk of GI cancer in individuals with BAD.

Comparison between SeHCAT test and clinical response to cholestyramine in patients with chronic diarrhea and high suspicion of bile acid malabsorption: A single-center prospective study

OBJECTIVES

We aimed to evaluate the clinical response to cholestyramine in patients with functional chronic diarrhea and a high clinical suspicion of bile-acid diarrhea (BAD) investigated with 75-selenium homocholic acid taurine (SeHCAT) test.

METHODS

Adult patients attending our outpatient clinic between January and December 2021 for chronic diarrhea with suspicion of BAD were proposed SeHCAT testing and a therapeutic trial of cholestyramine 4-8 g daily. Clinical response to cholestyramine was evaluated at 1, 3, 6, and 12 months. Clinical and demographic data were analyzed according to SeHCAT test results.

RESULTS

Among the 50 patients with chronic diarrhea and clinical suspicion of BAD, 13 (26.0%) refused either SeHCAT testing or cholestyramine therapy. Finally, 37 patients (31 females, age 44 ± 14 years) agreed to undergo SeHCAT and were started on cholestyramine (median follow-up 14 months [interquartile range 6-16 months]). Initial response to cholestyramine was similar in patients with positive and negative SeHCAT test results, but improved over time in those with a positive test result. Long-term response (100% vs 65.2%, P = 0.02) and necessity of maintenance therapy for symptom control were more common in those with positive SeHCAT test result (71.4% vs 26.1%, P = 0.02). However, response to cholestyramine was also frequent in patients with a negative test result.

CONCLUSIONS

The SeHCAT test accurately identifies patients with BAD who benefit from long-term cholestyramine treatment. Nevertheless, cholestyramine may be also effective in patients with chronic diarrhea but negative SeHCAT test result.

[Bile Acid Diarrhea]

Diarrhea is a very common gastrointestinal symptom, and the presence of higher concentrations of bile acid in the colon leads to bile acid diarrhea (BAD). In BAD patients, a portion of bile from the small intestine that is normally controlled by enterohepatic circulation is present at a high concentration in the lumen of the large intestine, resulting in increased motility and secretion of the large intestine. The prevalence of BAD is estimated to be 1-2% of the general population, and it comprises one-third of the instances of diarrhea-predominant irritable bowel syndrome. The clinical symptoms of BAD include chronic diarrhea, increased frequency of defecation, urgency to defecate, fecal incontinence, and cramping abdominal pain. The pathophysiology of BAD has not yet been fully elucidated. However, recent studies have reported increased intestinal permeability, shortened intestinal transit time, and changes in the intestinal microbial community to be the possible causes of BAD. Although fecal and serum bile acid tests are widely used for diagnosis, new test methods that are non-invasive, inexpensive, and have high sensitivity and specificity are needed at various institutions to facilitate the diagnosis. The selenium homo-tauro-cholic acid (SeHCAT) test is the gold standard for BAD diagnosis and severity assessment. The validation of several other serum markers, such as 7-hydroxy-4-cholesten-3-one (serum 7αC4) and the fibroblast growth factor 19 (FGF19) for use in clinical practice is ongoing. Although bile acid sequestrants are the mainstay of treatment, the development of drugs that are more effective and have better compliance is required. Farnesoid X receptor (FXR) agonists are showing promising results.

Journal of Clinical Gastroenterology Lectureship Dubai 2022 : Management of Irritable Bowel Syndrome With Diarrhea

Irritable bowel syndrome (IBS) with diarrhea (IBS-D) affects ~1% of the general population and is characterized by abdominal pain associated with diarrhea. IBS-D symptoms significantly impact the quality of life of patients. Major uncertainties remain regarding the optimal management of these patients. Several therapies have been investigated over the years for the treatment of IBS-D. In the initial management, commonly prescribed approaches with an effect on global IBS symptoms include a low Fermentable Oligo-, Di-, Mono-Saccharides and Polyols diet and probiotics, while antispasmodics are used for targeting abdominal pain and loperamide for diarrhea only. Additional therapeutic options for the relief of global IBS symptoms include rifaximin, 5-HT 3 antagonists, gut-directed psychological therapies, and eluxadoline, while tricyclic antidepressants can target abdominal pain and bile acid sequestrants diarrhea. Promising evidence exists for the use of mesalazine and fecal microbiota transplantation in IBS-D, although further evidence is needed for definitive conclusions regarding their efficacy.

The Epidemiology of Bile Acid Diarrhea in Denmark

OBJECTIVE

Bile acid diarrhea (BAD) is a socially debilitating disease with frequent bowel movements, urgency, and fecal incontinence as the main symptoms. It is caused by excessive bile acid levels in the colon and is most commonly treated with bile acid sequestrants. It is estimated that 1-2% of the population suffers from the disease, but only a fraction of these are properly diagnosed with the gold standard ⁷⁵selenium-homotaurocholic acid (SeHCAT) test. Here, we use nationwide registries to describe the demographic characteristics of individuals suffering from BAD in Denmark.

METHODS

Since the International Classification of Diseases diagnosis code for BAD was not used until 2021, we identified the BAD population by referral to SeHCAT testing followed by a prescription of a bile acid sequestrant (colestyramine, colestipol or colesevelam) within 365 days. The study period was from 2003 to 2021.

RESULTS

During the study period, a total of 5264 individuals with BAD were identified with large differences between the five regions in Denmark. The number of prescriptions of colestyramine and colesevelam, the number of SeHCAT tests, and the number of individuals diagnosed with BAD increased during the study period. The BAD population had more co-morbidities and more health care contacts as well as lower levels of education and income compared with age- and sex-matched controls from the general population.

CONCLUSION

Using the Danish registries, we identified a BAD population, which seems to be inferior in health care and socio-economic parameters compared with the Danish general population.

Diagnosis and treatment of post-cholecystectomy diarrhoea

The incidence of cholecystitis is relatively high in developed countries and may usually be attributed to gallstones, the treatment for which involves complete surgical removal of the gallbladder (cholecystectomy). Bile acids produced following cholecystectomy continue to flow into the duodenum but are poorly absorbed by the colon. Excessive bile acids in the colon stimulate mucosal secretion of water and electrolytes leading, in severe cases, to diarrhoea. Bile acid diarrhoea (BAD) is difficult to diagnose, requiring a comprehensive medical history and physical examination in combination with laboratory evaluation. The current work reviews the diagnosis and treatment of BAD following cholecystectomy.

Serum lipidome unravels a diagnostic potential in bile acid diarrhoea

OBJECTIVE

Bile acid diarrhoea (BAD) is debilitating yet treatable, but it remains underdiagnosed due to challenging diagnostics. We developed a blood test-based method to guide BAD diagnosis.

DESIGN

We included serum from 50 treatment-naive patients with BAD diagnosed by gold standard 75selenium homotaurocholic acid test, 56 feature-matched controls and 37 patients with non-alcoholic fatty liver disease (NAFLD). Metabolomes were generated using mass spectrometry covering 1295 metabolites and compared between groups. Machine learning was used to develop a BAD Diagnostic Score (BDS).

RESULTS

Metabolomes of patients with BAD significantly differed from controls and NAFLD. We detected 70 metabolites with a discriminatory performance in the discovery set with an area under receiver-operating curve metric above 0.80. Logistic regression modelling using concentrations of decanoylcarnitine, cholesterol ester (22:5), eicosatrienoic acid, L-alpha-lysophosphatidylinositol (18:0) and phosphatidylethanolamine (O-16:0/18:1) distinguished BAD from controls with a sensitivity of 0.78 (95% CI 0.64 to 0.89) and a specificity of 0.93 (95% CI 0.83 to 0.98). The model was independent of covariates (age, sex, body mass index) and distinguished BAD from NAFLD irrespective of fibrosis stage. BDS outperformed other blood test-based tests (7-alpha-hydroxy-4-cholesten-3-one and fibroblast growth factor 19) currently under development.

CONCLUSIONS

BDS derived from serum metabolites in a single-blood sample showed robust identification of patients with BAD with superior specificity and sensitivity compared with current blood test-based diagnostics.

Emerging uses of glucagon-like peptide 1 (GLP-1) receptor agonists following ileal resection: literature review and case examples

Following ileal resection, the combination of severe bile acid (BA) malabsorption, rapid small bowel transit and unrestricted upper gastrointestinal (GI) secretion results in severe diarrhoea that can prove refractory to pharmacological therapies. While established therapies, including BA sequestrants and antidiarrhoeal drugs seek to ameliorate symptoms, they do not target the underlying pathophysiological mechanisms in this patient group. Their use can also be limited by both intolerance and adverse effects. The novel use of glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) in these patients may allow restoration of the physiological negative feedback mechanisms lost in ileal resection and reduce diarrhoea by prolonging small bowel transit time, limiting upper GI secretions and perhaps by inhibiting hepatic BA synthesis. While recent evidence supports the use of GLP-1 RAs as a safe and effective therapy for bile acid diarrhoea (BAD), it remains uncertain whether those with severe BAD and subsequent short bowel syndrome secondary to extensive ileal resection will benefit. Here, we present three cases of severe diarrhoea secondary to extensive ileal resection in which the use of the GLP-1 RA, liraglutide, was well tolerated and resulted in an objective improvement in diarrhoeal symptoms. We further provide a narrative review of the emerging evidence base supporting the use of GLP therapies in this challenging condition.

Bile Acid Sequestrants Based on Natural and Synthetic Gels

Bile acid sequestrants (BASs) are non-systemic therapeutic agents used for the management of hypercholesterolemia. They are generally safe and not associated with serious systemic adverse effects. Usually, BASs are cationic polymeric gels that have the ability to bind bile salts in the small intestine and eliminate them by excretion of the non-absorbable polymer-bile salt complex. This review gives a general presentation of bile acids and the characteristics and mechanisms of action of BASs. The chemical structures and methods of synthesis are shown for commercial BASs of first- (cholestyramine, colextran, and colestipol) and second-generation (colesevelam and colestilan) and potential BASs. The latter are based on either synthetic polymers such as poly((meth)acrylates/acrylamides), poly(alkylamines), poly(allylamines) and vinyl benzyl amino polymers or biopolymers, such as cellulose, dextran, pullulan, methylan, and poly(cyclodextrins). A separate section is dedicated to molecular imprinting polymers (MIPs) because of their great selectivity and affinity for the template molecules used in the imprinting technique. Focus is given to the understanding of the relationships between the chemical structure of these cross-linked polymers and their potential to bind bile salts. The synthetic pathways used in obtaining BASs and their in vitro and in vivo hypolipidemic activities are also introduced.

Safety, tolerability, and efficacy of maralixibat in adults with primary sclerosing cholangitis: Open-label pilot study

BACKGROUND

Primary sclerosing cholangitis (PSC) is frequently associated with pruritus, which significantly impairs quality of life. Maralixibat is a selective ileal bile acid transporter (IBAT) inhibitor that lowers circulating bile acid (BA) levels and reduces pruritus in cholestatic liver diseases. This is the first proof-of-concept study of IBAT inhibition in PSC.

METHODS

This open-label study evaluated the safety and tolerability of maralixibat ≤10 mg/d for 14 weeks in adults with PSC. Measures of pruritus, biomarkers of BA synthesis, cholestasis, and liver function were also assessed.

RESULTS

Of 27 enrolled participants, 85.2% completed treatment. Gastrointestinal treatment-emergent adverse events (TEAEs) occurred in 81.5%, with diarrhea in 51.9%. TEAEs were mostly mild or moderate (63.0%); 1 serious TEAE (cholangitis) was considered treatment related. Mean serum BA (sBA) levels decreased by 16.7% (-14.84 µmol/L; 95% CI, -27.25 to -2.43; p = 0.0043) by week 14/early termination (ET). In participants with baseline sBA levels above normal (n = 18), mean sBA decreased by 40.0% (-22.3 µmol/L, 95% CI, -40.38 to -4.3; p = 0.004) by week 14/ET. Liver enzyme elevations were not significant; however, increases of unknown clinical significance in conjugated bilirubin levels were observed. ItchRO weekly sum scores decreased from baseline to week 14/ET by 8.4% (p = 0.0495), by 12.6% (p = 0.0275) in 18 participants with pruritus at baseline, and by 70% (p = 0.0078) in 8 participants with ItchRO daily average score ≥3 at baseline.

CONCLUSIONS

Maralixibat was associated with reduced sBA levels in adults with PSC. In participants with more severe baseline pruritus, pruritus improved significantly from baseline. TEAEs were mostly gastrointestinal related. These results support further investigation of IBAT inhibitors for adults with PSC-associated pruritus. ClinicalTrials.gov: NCT02061540.

Bile acid diarrhea - as bad as it gets?

PURPOSE OF REVIEW

Bile acid diarrhea (BAD) is a common but under-recognized gastrointestinal condition that manifests with increased stool frequency and urgency, and a looser stool consistency. The aim of this review is to present recent advances in the pathophysiology, mechanisms, manifestations, diagnosis, and treatment of BAD.

RECENT FINDINGS

Patients with BAD have evidence of accelerated colonic transit, increased gut mucosal permeability, altered stool microbiome composition, and decreased quality of life. Single, random stool measurements of bile acids, alone or in combination with fasting serum 7-alpha-hydroxy-4-cholesten-3-one, have shown good sensitivity and specificity for the diagnosis of BAD. Novel therapeutic approaches include farnesoid X receptor agonists and glucagon-like peptide 1 agonists.

SUMMARY

Recent research has led to a better understanding of the pathophysiology and mechanisms of BAD, which might pave the way towards more targeted treatment strategies for BAD. Newer, more affordable, and easier diagnostic methods facilitate the diagnosis of BAD.

Chologene Diarrhö, Stiefkind der chronischen Diarrhö – Prävalenz, Diagnostik und Therapie

Die chologene Diarrhö ist eine der häufigsten nicht diagnostizierten Ursachen der chronischen Diarrhö, der zahlreiche verschiedene Pathophysiologien zugrunde liegen können. Auch nach Ausschlussdiagnostik der häufigeren Ursachen verbleiben bis zu 5% der Bevölkerung von einer ungeklärten chronischen Diarrhö betroffen. In diesem Kollektiv findet sich in bis zu 50% als Ursache eine chologene Diarrhö.

Effectiveness of diet, psychological, and exercise therapies for the management of bile acid diarrhoea in adults: A systematic review

BACKGROUND

Bile acid diarrhoea (BAD) causes chronic diarrhoea and is primarily treated pharmacologically. This systematic review aimed to evaluate the effectiveness of non-pharmacological therapies for evidence-based management of BAD in adults.

METHODS

A systematic review of the medical literature was performed from 1975 to 13 July 2021 to identify studies on diet, psychological, and exercise therapies that met diagnostic criteria for BAD in adults with diarrhoea. Effectiveness was judged by responder or improvement in diarrhoea at study endpoint according to each study's definition of diarrhoea. Therapeutic effect on abdominal pain and flatulence was also measured. Risk of bias was assessed using the Risk Of Bias In Non-Randomised Studies of Interventions tool. A narrative review was conducted using 'Synthesis Without Meta-analysis' guidance. Certainty of the evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation.

RESULTS

Eight prospective cohort studies were identified on diet therapies from 2 weeks to over 2 years involving 192 patients. No psychological or exercise therapies were found. Carbohydrate modification (one study, n = 2) in primary BAD, and dietary fat intake reductions (five studies, n = 181) and an exclusive elemental diet therapy (two studies, n = 9) in secondary BAD, showed beneficial directions of effect on diarrhoea, abdominal pain, and flatulence. Risks of bias for each study and across studies for each therapy type were serious. Certainty of the evidence was very low for all outcomes.

CONCLUSIONS

No conclusions could be drawn on the effectiveness of diet, psychological, or exercise therapies on diarrhoea, abdominal pain, and flatulence for the management of BAD in adults. High-quality randomised controlled trials are needed.

Chronic loose stools following right-sided hemicolectomy for colon cancer and the association with bile acid malabsorption and small intestinal bacterial overgrowth

AIM

Patients treated with right-sided hemicolectomy for colon cancer may suffer from long-term bowel dysfunction, including loose stools, urgency and faecal incontinence. The underlying causes are poorly understood. The aim of this case-control study was to investigate the aetiology of chronic loose stools among patients with right-sided hemicolectomy curatively operated for cancer.

METHOD

Cases with chronic loose stools (Bristol stool type 6-7) after right-sided hemicolectomy were compared with a control group of patients with right-sided hemicolectomy without loose stools. All patients underwent a selenium-75 homocholic acid taurine (SeHCAT) scan to diagnose bile acid malabsorption (BAM) and a glucose breath test to diagnose small intestinal bacterial overgrowth (SIBO). Gastrointestinal transit time (GITT) was assessed with radiopaque markers. In a subgroup of patients, fibroblast growth factor 19 (FGF19) was measured in fasting blood. SIBO was treated with antibiotics and BAM was treated with bile acid sequestrants.

RESULTS

We included 45 cases and 19 controls. In the case group, 82% (n = 36) had BAM compared with 37% (n = 7) in the control group, p < 0.001. SIBO was diagnosed in 73% (n = 33) of cases with chronic loose stools and in 74% (n = 14) of controls, p = 0.977. No association between BAM and SIBO was observed. GITT was similar in cases and controls. No difference in median FGF19 was observed between cases and controls (p = 0.894), and no correlation was seen between FGF19 and SeHCAT retention (r_s 0.20, p = 0.294). Bowel symptoms among cases were reduced after treatment.

CONCLUSION

BAM and SIBO are common in patients having undergone right-sided hemicolectomy for cancer. Chronic loose stools were associated with BAM but not with SIBO.

A dynamic multiple reaction monitoring strategy to develop and optimize targeted metabolomics methods: Analyzing bile acids in capecitabine-induced diarrhea

OBJECTIVE

We sought to develop and optimize a targeted bile acids (BAs) metabolomics method based on a dynamic multiple reaction monitoring (dMRM) strategy and explored the dynamic alterations of BAs in diarrhea induced by capecitabine in a mouse model.

METHOD

The targeted metabolomics method was developed using an Agilent 6460A triple quadrupole mass spectrometer, and 41 types of BAs were monitored in negative ionization mode. The mass spectrometer detection was optimized using dMRM to enhance the responses, separation, and peak shape and to shorten the analysis time. A mouse model of diarrhea was established by multiple administration of capecitabine, and plasma samples were collected at baseline and the end of drug administration for subsequent BAs analysis.

RESULTS

The targeted BA metabolomics method achieved shorter chromatographic separation time (10 min) for 41 BAs, with good peak shapes and response increases of 3- to 10-fold after application of dMRM. The mouse model of capecitabine-induced diarrhea was established, and the three BAs 23-norcholic acid, isolithocholic acid, and isodeoxycholic acid in the baseline samples contributed the most to differentiating mice with diarrhea from those without diarrhea. For mice that ultimately developed diarrhea, apocholic acid, isodeoxycholic acid, and 7-ketodeoxycholic acid exhibited the largest change in concentrations compared with their baseline concentrations.

CONCLUSION

The dMRM strategy has obvious advantages compared with common MRM. The results in model mice showed that a differentiated profile of BAs in the baseline may indicate biomarkers of diarrhea induced by capecitabine, and disturbed homeostasis may explain the metabolomic mechanism of diarrhea occurrence.

Advances in the Comprehensive Management of Postoperative Crohn's Disease

Patients with postoperative Crohn's disease are difficult to manage because of their risk of experiencing a more severe course, multiple symptom confounders, and poor sensitivity of symptomatic remission to rule out intestinal inflammation. In this group, data are lacking on biologic therapeutic efficacy, and recommendations are lacking for those with multiple medication failures. Novel noninvasive testing can simultaneously exclude alternate causes of symptoms (serum C4, fecal fat, small intestinal bowel overgrowth breath testing) and assess intestinal inflammation (fecal calprotectin, endoscopic healing index). In addition, endoscopy-based disease activity assessment and management are required. Endoscopy should be performed within 6 months of surgery, and aggressive disease activity monitoring can be considered with colonoscopy every 1-2 years subsequently to ensure late recurrence is detected. Patients with multiple resections should be screened for short bowel syndrome. Predictive biomarkers are needed to guide medication selection in this high-risk population. Postoperative prophylactic biologic therapy is prudent for patients with preoperative biologic failure. However, there are no high-quality data to guide which agent should be selected. Selecting biologics with an alternative mechanism of action in those who had failed a biologic with adequate drug concentrations and selection of different agents in those with previous intolerance are reasonable. Significantly more study is required to assess the efficacy of therapies in this setting.

Functional bowel disorders with diarrhoea: Clinical guidelines of the United European Gastroenterology and European Society for Neurogastroenterology and Motility

Irritable bowel syndrome with diarrhoea (IBS‐D) and functional diarrhoea (FDr) are the two major functional bowel disorders characterized by diarrhoea. In spite of their high prevalence, IBS‐D and FDr are associated with major uncertainties, especially regarding their optimal diagnostic work‐up and management. A Delphi consensus was performed with experts from 10 European countries who conducted a literature summary and voting process on 31 statements. Quality of evidence was evaluated using the grading of recommendations, assessment, development, and evaluation criteria. Consensus (defined as >80% agreement) was reached for all the statements. The panel agreed with the potential overlapping of IBS‐D and FDr. In terms of diagnosis, the consensus supports a symptom‐based approach also with the exclusion of alarm symptoms, recommending the evaluation of full blood count, C‐reactive protein, serology for coeliac disease, and faecal calprotectin, and consideration of diagnosing bile acid diarrhoea. Colonoscopy with random biopsies in both the right and left colon is recommended in patients older than 50 years and in presence of alarm features. Regarding treatment, a strong consensus was achieved for the use of a diet low fermentable oligo‐, di‐, monosaccharides and polyols, gut‐directed psychological therapies, rifaximin, loperamide, and eluxadoline. A weak or conditional recommendation was achieved for antispasmodics, probiotics, tryciclic antidepressants, bile acid sequestrants, 5‐hydroxytryptamine‐3 antagonists (i.e. alosetron, ondansetron, or ramosetron). A multinational group of European experts summarized the current state of consensus on the definition, diagnosis, and management of IBS‐D and FDr.

Bile Acid Diarrhea in Adults and Adolescents

BACKGROUND

Bile acids are central to enterohepatic signaling pathways activated through natural receptors, farnesoid X receptor [FXR mediates synthesis of fibroblast growth factor-19 (FGF-19)], and G protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5). Although bile acid diarrhea (BAD) is more commonly encountered in ileal resection or disease, there is evidence documenting "idiopathic" BAD in about 20% of adolescents and 30% of adults presenting with chronic, non-bloody diarrhea often attributed to irritable bowel syndrome. Mechanism(s) leading to increased hepatic synthesis and colonic bile acid levels in "idiopathic" BAD include reduced synthesis of FGF-19 by the ileal mucosa, or genetic variation in hepatocyte proteins klotho β and FGF receptor 4 (FGFR4) that mediate negative feedback of bile acid synthesis.

PURPOSE

The objective of this review is to summarize the diagnosis of BAD in adults and adolescents. In addition to ⁷⁵ SeHCAT retention for diagnosis of BAD, studies have validated fasting serum 7αC4 and FGF-19, respectively, by-product and inhibitor of hepatic bile acid synthesis, as well as fecal bile acid measurements. These assays are widely available through reference laboratories, and they are being simplified (eg, measurement of primary fecal bile acids in a random stool sample). BAD has also been identified as a co-factor contributing to persistent diarrhea in other diseases in remission including inflammatory bowel disease, microscopic colitis, celiac disease, and neuroendocrine tumors. In summary, advances in diagnosis of BAD provide opportunities for generalists and pediatric and adult gastroenterologists to provide targeted treatment for BAD presenting as chronic non-bloody diarrhea.

Enterohepatic, Gluco-metabolic, and Gut Microbial Characterization of Individuals With Bile Acid Malabsorption

Background and Aims

Bile acid malabsorption (BAM) is a debilitating disease characterized by loose stools and high stool frequency. The pathophysiology of BAM is not well-understood. We investigated postprandial enterohepatic and gluco-metabolic physiology, as well as gut microbiome composition and fecal bile acid content in patients with BAM.

Methods

Twelve participants with selenium-75 homocholic acid taurine test-verified BAM and 12 healthy controls, individually matched on sex, age, and body mass index, were included. Each participant underwent 2 mixed meal tests (with and without administration of the bile acid sequestrant colesevelam) with blood sampling and evaluation of gallbladder motility; bile acid content and microbiota composition were evaluated in fecal specimens.

Results

Patients with BAM were characterized by increased bile acid synthesis as assessed by circulating 7-alpha-hydroxy-4-cholesten-3-one, fecal bile acid content, and postprandial concentrations of glucose, insulin, C-peptide, and glucagon. The McAuley index of insulin sensitivity was lower in patients with BAM than that in healthy controls. In patients with BAM, colesevelam co-administered with the meal reduced postprandial concentrations of bile acids and fibroblast growth factor 19 and increased 7-alpha-hydroxy-4-cholesten-3-one concentrations but did not affect postprandial glucagon-like peptide 1 responses or other gluco-metabolic parameters. Patients with BAM were characterized by a gut microbiome with low relative abundance of bifidobacteria and high relative abundance of Blautia, Streptococcus, Ruminococcus gnavus, and Akkermansia muciniphila.

Conclusion

Patients with BAM are characterized by an overproduction of bile acids, greater fecal bile acid content, and a gluco-metabolic profile indicative of a dysmetabolic prediabetic-like state, with changes in their gut microbiome composition potentially linking their enterohepatic pathophysiology and their dysmetabolic phenotype. ClinicalTrials.gov number NCT03009916.

Bile Acid Malabsorption as a Consequence of Cancer Treatment: Prevalence and Management in the National Leading Centre

The aim was to establish prevalence of bile acid malabsorption (BAM) and management in patients who underwent treatment for malignancy. Retrospective evaluation of data in patients seen within six months (August 2019-January 2020) was carried out. Demographic, nuclear medicine (Selenium Homocholic Acid Taurine (SeHCAT) scan result), clinical (previous malignancy, type of intervention (medication, diet), response to intervention) and laboratory (vitamin D, vitamin B12 serum levels) data were searched. In total, 265 consecutive patients were reviewed. Out of those, 87/265 (33%) patients (57 females, 66%) were diagnosed with BAM. Mean age was 59 +/- 12 years. The largest group were females with gynaecological cancer (35), followed by haematology group (15), colorectal/anal (13), prostate (9), upper gastrointestinal cancer (6), another previous malignancy (9). Severe BAM was most common in haematology (10/15; 67%) and gynaecological group (21/35; 60%). Medication and low-fat diet were commenced in 65/87 (75%), medication in 10/87 (11%), diet in 6/87 (7%). Colesevelam was used in 71/75 (95%). Symptoms improved in 74/87 (85%) patients. Vitamin D insufficiency/deficiency was diagnosed in 62/87 (71%), vitamin B12 deficiency in 39/87 (45%). BAM is a common condition in this cohort however treatments are highly effective.

Enterosorption in the Treatment of Heavy Metal Poisoning

Enterosorption is a cost-effective and efficient approach to reducing the impact of chronic exposure to heavy metals and radionuclides. As an auxiliary method to medical treatment, it can protect population chronically exposed to the intake of heavy metals or radioactivity due to industrial activities or in the aftermath of technogenic or natural accidents. This paper assesses the current state of the art in the treatment of acute and chronic heavy metal poisoning.

Review Article: Current and future treatment approaches for IBS with diarrhoea (IBS-D) and IBS mixed pattern (IBS-M)

BACKGROUND

Irritable bowel syndrome-diarrhoea (IBS-D) and IBS-mixed stool pattern (IBS-M) are disorders of gut-brain interaction characterised by abdominal pain associated with diarrhoea or both diarrhoea and constipation respectively. The pathophysiology of IBS-D/M is multifactorial and not completely understood; thus, treatment is aimed at multiple mechanisms such as altering gut microbiota, visceral hypersensitivity, intestinal permeability, gut-brain interaction and psychological strategies.

AIM

The goal of this article was to provide an up-to-date review of the current evidence for both non-pharmacological and pharmacological treatment options in IBS-D and IBS-M. Future treatments for IBS-D and IBS-M will also be discussed.

METHODS

Medline and Embase database searches (through April 30 2021) to identify clinical studies in subjects with IBS-D in which dietary modification, alternative treatments (probiotics, acupuncture, exercise) as well as FDA-approved medications were used.

RESULTS

Dietary modification is often the first line of therapy. Furthermore, lifestyle treatments include complementary alternative medications (CAM), probiotics and peppermint oil are useful adjuncts but have not specifically been described in IBS-D/M. Evidence strongly supports psychotherapy in the treatment of IBS. Beyond over-the counter anti-diarrhoeals, anti-spasmodics and anti-depressants, pharmacological treatment now includes treating for bile acid malabsorption and the FDA-approved medications rifaximin, eluxadoline and alosetron.

CONCLUSIONS

The treatment of IBS-D/M ideally involves a multidisciplinary approach of primary care, gastroenterologist and psychologist. Treatment often involves both non-pharmacological and pharmacological therapies. Future therapies may include faecal microbial transplant, Crofelemer and serotonin antagonists, but further studies are needed.

Markers of Bile Acid Metabolism in Pediatric Diarrhea Predominant Irritable Bowel Syndrome and Healthy Controls

OBJECTIVES

Excessive fecal bile acids in adults have been associated with diarrhea-predominant irritable bowel syndrome (IBS-D), but their role in pediatric IBS-D is unknown. Serum markers including 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor-19 (FGF-19) were validated in adults to detect bile acid diarrhea (BAD) compared to 48-hour fecal bile acid collection (48FBA). Our aims were to assess fasting serum C4 and FGF-19 and 48FBA in a pediatric population, to compare measurements in IBS-D patients and healthy controls (HC), and to determine the prevalence of BAD among children with IBS-D.

METHODS

Using a cross-sectional design, 26 patients with IBS-D and 56 HC were recruited in two pediatric tertiary care centers. Fasting serum C4 and FGF-19 and 48FBA were obtained. Participants completed a 7-day bowel diary coinciding with stool collection. Associations were analyzed using Spearman correlations.

RESULTS

Mean age was 14.7 ± 2.5 years (42.3% female) in IBS-D and 12.6 ± 2.4 years (39.3% female) in HC. There was a significant correlation of C4 with 48FBA (r = 0.48, P < 0.05) and an inverse association with FGF-19 (r = -0.43, P < 0.05). No significant differences were noted in C4 (P = 0.32), FGF-19 (P = 0.1), or 48FBA (P = 0.5) between IBS-D and HC groups; however, 20% of IBS-D patients had elevated C4 and 28% had low FGF-19 values.Fecal primary BA was significantly correlated with stool frequency (r = 0.45, P < 0.002).

CONCLUSIONS

Correlations of C4 with 48FBA and FGF-19 are confirmed in a pediatric population. Twenty percent of pediatric patients with IBS-D had abnormal fasting serum C4. This serum test could be applied to identify BAD in pediatric IBS-D.

[Bile acid diarrhea, stepchild of chronic diarrhea - prevalence, diagnosis and treatment. Update 2021]

Bile acid diarrhea is one of the most frequently undiagnosed causes of chronic diarrhea. A variety of different pathophysiologic causes can underlie chronic diarrhea. Even after exclusion of the more frequent causes, up to 5 % of the population remains affected by unexplained chronic diarrhea. In up to 50 % within this cohort, bile acid diarrhea is the underlying cause.The various pathophysiologies leading to bile acid diarrhea are well characterized. In this way, bile acid diarrhea can be divided into primary, secondary and tertiary subtypes. Common to all causes is the increased amount of bile acids in the colon and in the faeces and the resulting secretory-osmotic diarrhea, in more severe forms in combination with steatorrhea. The diagnosis of bile acid diarrhea follows a clear algorithm which, in addition to the search for the cause and possibly a therapeutic trial, recognizes the 75SeHCAT test as the reference method for the detection of an increased loss of bile acids. In view of the chronic nature of the symptoms and the need for permanent, lifelong therapy, the use of a one-time, reliable diagnostic test is justified, though the test is currently only available at a few centers. In addition to the treatment of identifiable underlying diseases, the current treatment includes the use of drugs that bind bile acids, with additional nutritional recommendations and vitamin substitutions.The present review article summarizes the pathophysiology and importance of bile acid diarrhea and discusses the current approach towards diagnosis and treatment.

Physiology and Physical Chemistry of Bile Acids

Bile acids (BAs) are facial amphiphiles synthesized in the body of all vertebrates. They undergo the enterohepatic circulation: they are produced in the liver, stored in the gallbladder, released in the intestine, taken into the bloodstream and lastly re-absorbed in the liver. During this pathway, BAs are modified in their molecular structure by the action of enzymes and bacteria. Such transformations allow them to acquire the chemical-physical properties needed for fulling several activities including metabolic regulation, antimicrobial functions and solubilization of lipids in digestion. The versatility of BAs in the physiological functions has inspired their use in many bio-applications, making them important tools for active molecule delivery, metabolic disease treatments and emulsification processes in food and drug industries. Moreover, moving over the borders of the biological field, BAs have been largely investigated as building blocks for the construction of supramolecular aggregates having peculiar structural, mechanical, chemical and optical properties. The review starts with a biological analysis of the BAs functions before progressively switching to a general overview of BAs in pharmacology and medicine applications. Lastly the focus moves to the BAs use in material science.

Protocol for a randomised, double-blinded, placebo-controlled, double-dummy 6-week clinical trial comparing the treatment effects of the glucagon-like peptide 1 receptor agonist liraglutide versus the bile acid sequestrant colesevelam on bile acid malabsorption

INTRODUCTION

Bile acid malabsorption (BAM) is a socially debilitating disease characterised by high stool frequency and urgency caused by a spillover of bile acids into the colon. Bile acid sequestrants (BASs) have limited therapeutic effect but represent the only available treatment option. Cases reporting total remission of BAM-related symptoms after treatment with liraglutide, a glucagon-like peptide 1 analogue, prompted us to design a clinical trial investigating the therapeutic effect of this compound in patients with BAM.

METHODS AND ANALYSIS

Fifty adult individuals with moderate or severe BAM as assessed by the ⁷⁵selenium-homotaurocholic acid test (SeHCAT) will, after a run-in period of 10 days with no BAM treatment, be randomised to either treatment with the BAS colesevelam or liraglutide (double blinded) for 6 weeks. Daily symptom diaries and questionnaires will be filled in. Blood and faecal samples will be collected and SeHCAT will be performed at baseline, after week 3 and at end of trial. The primary endpoint is change in daily stool frequency. Secondary endpoints include changes from baseline in questionnaires, biochemistry, SeHCAT and faecal bile acid content and microbial composition.

ETHICS AND DISSEMINATION

The study complies with Danish and European Union legislation and is approved by the Danish Medicines Agency, the Regional Scientific Ethics Committee of the Capital Region of Denmark and the Danish Data Protection Agency. The study is monitored by the Capital Region of Denmark's good clinical practice unit. All results, positive, negative and inconclusive, will be disseminated at national and/or international scientific meetings and in peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

EudraCA: 2018-003575-34; Pre-results.

Prevalence and clinical features of bile acid diarrhea in patients with chronic diarrhea

OBJECTIVE

Bile acid diarrhea is a form of chronic diarrhea caused by excessive bile reaching the colon. Conditions involving the terminal ileum and cholecystectomy are predisposing factors but an idiopathic form of bile acid diarrhea has also been described. In this study we aimed to evaluate the prevalence of bile acid diarrhea in patients consecutively evaluated for chronic diarrhea in an Outpatient Gastroenterology Clinic.

METHODS

Medical records of all patients admitted for chronic diarrhea (>4 weeks) between June 2018 and April 2019 were retrospectively reviewed. Bile acid diarrhea was suspected in patients with ileal disease, cholecystectomy or post-prandial diarrhea. Patients' age at diagnosis, sex, presenting symptoms, results of main test and examinations, final diagnoses and date of last follow-up visit were also collected. Exclusion of chronic diarrhea of other causes and a 6-month clinical improvement with cholestyramine treatment confirmed the diagnosis of bile acid diarrhea.

RESULTS

In total, 139 patients aged 46 ± 20 years (76 women and 63 men) were included. Diarrhea due to an organic cause was diagnosed in 16 patients. A clinical response to cholestyramine persisting for more than 6 months led to a diagnosis of bile acid diarrhea in 39 (aged 52 ± 19 years) out of the remaining 123 patients with functional forms of diarrhea. Therefore, the prevalence of bile acid diarrhea was 28.1% (95% confidence interval 19.9%-38.4%) in patients with chronic diarrhea.

CONCLUSIONS

Bile acid diarrhea is a very common, yet under-recognized cause of chronic functional diarrhea. A therapeutic trial of cholestyramine is a valid diagnostic strategy.

Long-term gastrointestinal sequelae in colon cancer survivors: prospective pilot study on identification, the need for clinical evaluation and effects of treatment

AIM

The aim of the present pilot study was to describe the type and frequency of long-term gastrointestinal symptoms within a well-defined cohort of colon cancer survivors, their wish for clinical evaluation and treatment outcomes.

METHOD

A screening survey was sent to colon cancer survivors 12, 24 and 36 months after surgery. Based on their main symptoms, patients who wished to have a consultation were referred to the gastroenterological or surgical unit of our late cancer sequelae clinic. Treatment effect was monitored by questionnaires on bowel symptoms and the EuroQol five-dimensional (EQ-5D) quality-of-life score.

RESULTS

Overall, 953 patients who had survived colon cancer received the screening survey and 767 replied (response rate 80.5%). Of these, 76 (9.9%; 95% CI 7.9%-12.2%) were referred for algorithm-based clinical evaluation and treatment of bowel dysfunction. The majority were women (69.7%) who had undergone a right-sided colonic resection (65.8%). Patients reported various symptoms, mainly including urgency, fragmented defaecation, loose stools and incontinence for liquid stools. Patients with emptying difficulties and low anterior resection syndrome-like symptoms were referred to the surgical unit and patients with diarrhoea were referred to the gastroenterological unit for clinical work-up. Our main endpoint, mean EQ-5D index after treatment, was improved compared with baseline (baseline 0.809, after treatment 0.846; p = 0.049). After treatment, self-rated bowel function and several bowel symptoms were improved as well.

CONCLUSION

This study highlights the importance of identifying colon cancer survivors in need of treatment of late gastrointestinal sequelae and clinical management in a multidisciplinary team setting.

Biochemical Diagnosis of Bile Acid Diarrhea: Prospective Comparison With the 75Seleno-Taurohomocholic Acid Test

INTRODUCTION

The diagnosis of bile acid diarrhea is often missed because the availability of the seleno-taurohomocholic acid (SeHCAT) test is limited. We aimed to compare the biomarkers 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19) with the SeHCAT test.

METHODS

Patients with chronic diarrhea without intestinal resection referred for SeHCAT were prospectively recruited for this diagnostic accuracy study. Blood was sampled at fasting and after a stimulation meal with chenodeoxycholic acid. SeHCAT retention ≤10% defined bile acid diarrhea and >10% defined miscellaneous diarrhea. Receiver operating characteristics (ROC) were analyzed with SeHCAT as the gold standard. www.clinicaltrials.gov (NCT03059537).

RESULTS

Patients with bile acid diarrhea (n = 26) had mean C4 of 30 ng/mL (95% confidence interval: 19-46) vs 8 (7-11; P < 0.001) in the miscellaneous diarrhea group (n = 45). Area under the ROC curve (ROCAUC) for C4 was 0.83 (0.72-0.93). C4 < 15 ng/mL had 85% (74%-96%) negative predictive value; C4 > 48 ng/mL had 82% (59%-100%) positive predictive value. Twenty patients had C4 values 15-48 ng/mL, of whom 11/20 had SeHCAT ≤10%. Median fasting FGF19 was 72 pg/mL (interquartile range: 53-146) vs 119 (84-240) (P = 0.004); ROCAUC was 0.71 (0.58-0.83). Stimulated FGF19 responses did not differ (P = 0.54).

DISCUSSION

We identified C4 thresholds with clinically useful predictive values for the diagnosis of and screening for bile acid diarrhea in patients with chronic watery diarrhea. Further validation of the cutoff values with the placebo-controlled effect of sequestrant therapy is warranted (see Visual Abstract, Supplementary Digital Content 2, http://links.lww.com/AJG/B603).

Bile acid diarrhoea: Current and potential methods of diagnosis

Chronic diarrhoea is common and mostly due to diarrhoea predominant irritable bowel syndrome. Diarrhoea predominant irritable bowel syndrome affects about 11% of the population; however, up to a third of these patients actually have bile acid diarrhoea. There are, therefore, more than one million sufferers of bile acid diarrhoea in the UK. Bile acid diarrhoea is caused by small bowel malabsorption of bile acids and the increased bile acids in the large intestine cause diarrhoea. Once diagnosed, the treatment of bile acid diarrhoea is simple and effective. Bile acid diarrhoea , however, is often not diagnosed because of a lack of easily available and reliable diagnostic methods. In the United Kingdom, the radiolabelled 23-seleno-25-homotaurocholic acid test is the gold-standard method of diagnosis. 23-seleno-25-homotaurocholic acid test, however, is expensive, inconvenient to the patient, involves radiation exposure and has limited availability. As such, a laboratory biomarker is desirable. This review briefly discusses the pathophysiology and management of bile acid diarrhoea and critically evaluates methods for its diagnosis, including serum 7α-hydroxy-4-cholesten-3-one, faecal bile acid measurement, serum fibroblast growth factor 19, urine-2-propanol, and the ¹⁴C-glycocholate breath and stool test.

Discovery of Roblitinib (FGF401) as a Reversible-Covalent Inhibitor of the Kinase Activity of Fibroblast Growth Factor Receptor 4

FGF19 signaling through the FGFR4/β-klotho receptor complex has been shown to be a key driver of growth and survival in a subset of hepatocellular carcinomas, making selective FGFR4 inhibition an attractive treatment opportunity. A kinome-wide sequence alignment highlighted a poorly conserved cysteine residue within the FGFR4 ATP-binding site at position 552, two positions beyond the gate-keeper residue. Several strategies for targeting this cysteine to identify FGFR4 selective inhibitor starting points are summarized which made use of both rational and unbiased screening approaches. The optimization of a 2-formylquinoline amide hit series is described in which the aldehyde makes a hemithioacetal reversible-covalent interaction with cysteine 552. Key challenges addressed during the optimization are improving the FGFR4 potency, metabolic stability, and solubility leading ultimately to the highly selective first-in-class clinical candidate roblitinib.

The Role of Bile Acids in Chronic Diarrhea

Bile acids (BAs) are the central signals in enterohepatic communication, and they also integrate microbiota-derived signals into enterohepatic signaling. The tissue distribution and signaling pathways activated by BAs through natural receptors, farsenoid X receptor and G protein-coupled BA receptor 1 (GPBAR1, also known as Takeda G-coupled receptor 5), have led to a greater understanding of the mechanisms and potential therapeutic agents. BA diarrhea is most commonly encountered in ileal resection or disease, in idiopathic disorders (with presentation similar to functional diarrhea or irritable bowel syndrome with diarrhea), and in association with malabsorption such as chronic pancreatitis or celiac disease. Diagnosis of BA diarrhea is based on Se-homocholic acid taurine retention, 48-hour fecal BA excretion, or serum 7αC4; the latter being a marker of hepatic BA synthesis. BA diarrhea tends to be associated with higher body mass index, increased stool weight and stool fat, and acceleration of colonic transit. Biochemical markers of increased BA synthesis or excretion are available through reference laboratories. Current treatment of BA diarrhea is based on BA sequestrants, and, in the future, it is anticipated that farsenoid X receptor agonists may also be effective. The optimal conditions for an empiric trial with BA sequestrants as a diagnostic test are still unclear. However, such therapeutic trials are widely used in clinical practice. Some national guidelines recommend definitive diagnosis of BA diarrhea over empirical trial.

Randomised clinical trial: significant biochemical and colonic transit effects of the farnesoid X receptor agonist tropifexor in patients with primary bile acid diarrhoea

BACKGROUND

In primary bile acid diarrhoea, feedback by farnesoid X receptor (FXR) and fibroblast growth hormone 19 (FGF19) on hepatic bile acid production is impaired.

AIMS

To evaluate the safety, mechanisms and efficacy of negative feedback by FXR activation with tropifexor, a non-bile acid FXR agonist, in patients with primary bile acid diarrhoea.

METHODS

In this double-blind, multicentre, randomised, cross-over study, patients received tropifexor 60 µg or placebo once daily for 14 days in each of two treatment periods. Primary objectives included tropifexor safety and tolerability, and on stool frequency and form. Other assessments included pharmacokinetic and pharmacodynamic measures, biochemical markers and gastrointestinal transit.

RESULTS

Twenty patients (tropifexor 60 µg/placebo [N = 10]; placebo/tropifexor 60 µg [N = 10]) were enrolled. Adverse event rates were lower with tropifexor vs placebo (52.9% vs 73.7%). No patient had pruritus during tropifexor intake. There were no significant differences in stool frequency, stool form or loperamide use between treatments. Tropifexor increased FGF19 and decreased 7α-hydroxy-4-cholesten-3-one (C4) levels for up to 8 h. Plasma tropifexor concentrations peaked at 5 hours post-dose on days 1 and 12. At day 12, tropifexor caused reduction in peak total bile acid concentration (33%, P = 0.032) and exposure (36%, P = 0.005). Moreover, tropifexor showed a significant increase in ascending colon half-emptying time (P = 0.036).

CONCLUSIONS

Tropifexor 60 µg once daily had acceptable safety and tolerability. Changes in FGF19 and C4 showed effective target engagement; however, higher doses may be required to observe stool frequency changes. Slowing of ascending colon emptying suggests therapeutic potential of tropifexor in patients with primary bile acid diarrhoea. ClinicalTrials.gov number: NCT02713243.

Bile acid malabsorption in patients with chronic diarrhea and Crohn's disease

INTRODUCTION AND AIM

Crohn's disease (CD) is a form of inflammatory bowel disease and is mainly characterized by diarrhea and abdominal pain. The aim of our study was to analyze the usefulness of performing a 75SeHCAT scan in CD patients with chronic diarrhea and suspected bile acid malabsorption (BAM). In addition, we aimed to determine whether there was a relationship with the clinical features of the disease and a previous bowel resection.

PATIENTS AND METHODS

this was an observational cross-sectional study of 39 patients with a diagnosis of CD and chronic diarrhea. All cases underwent a 75SeHCAT scan for BAM diagnosis, after discarding disease activity.

RESULTS

the study cohort included 19 females and 20 males. The median age was 44 years and the majority of patients were A2 L1 B1 according to the Montreal classification; 84.6% of patients had undergone a previous bowel resection. BAM was present in 97.4% of patients (100% and 83.3% of patients with and without previous surgery, respectively), which was severe in 92.1% of cases. Treatment with bile acid sequestrants was initiated and a favorable response was obtained in 72.2% of patients. The relationship between BAM degree (moderate or severe), bowel surgery and the response to bile acid sequestrant treatment was also analyzed but not statistically significant.

CONCLUSION

BAM is a frequent cause of diarrhea in CD patients in endoscopic or radiological remission. This condition was present in all patients with a history of a bowel resection. A response to bile acid sequestrants treatment was observed in 73% of patients.

Bile acid receptors FXR and TGR5 signaling in fatty liver diseases and therapy

Bile acid synthesis is the most significant pathway for catabolism of cholesterol and for maintenance of whole body cholesterol homeostasis. Bile acids are physiological detergents that absorb, distribute, metabolize, and excrete nutrients, drugs, and xenobiotics. Bile acids also are signal molecules and metabolic integrators that activate nuclear farnesoid X receptor (FXR) and membrane Takeda G protein-coupled receptor 5 (TGR5; i.e., G protein-coupled bile acid receptor 1) to regulate glucose, lipid, and energy metabolism. The gut-to-liver axis plays a critical role in the transformation of primary bile acids to secondary bile acids, in the regulation of bile acid synthesis to maintain composition within the bile acid pool, and in the regulation of metabolic homeostasis to prevent hyperglycemia, dyslipidemia, obesity, and diabetes. High-fat and high-calorie diets, dysbiosis, alcohol, drugs, and disruption of sleep and circadian rhythms cause metabolic diseases, including alcoholic and nonalcoholic fatty liver diseases, obesity, diabetes, and cardiovascular disease. Bile acid-based drugs that target bile acid receptors are being developed for the treatment of metabolic diseases of the liver.

Chronic diarrhoea due to bile salt malabsorption: nurse-led assessment, medical treatment and dietary management

Bile salt malabsorption (BSM) occurs when bile salts, which are secreted in the small bowel to aid digestion of fats and vitamins, are not sufficiently re-absorbed in the terminal ileum. Consequently, an excess of bile salts enters the colon, causing chronic explosive diarrhoea, associated with abdominal cramps, flatulence and urgent, frequent and unpredictable bowel habits. BSM affects around 1% of the population, often occuring in ileal Crohn's disease or after ileal resection. Diagnosis begins with a nurse-led assessment, including blood and stool tests, to exclude other potential organic causes of chronic diarrhoea. BSM can then be confirmed and classified with a75Se-homocholic acid taurine (SeHCAT) scan. BSM can be treated medically with bile salt sequestrants, including colestyramine sachets, which are approved but have an unpleasant taste, and colesevelam tablets, which are more tolerable but more expensive and not yet approved. However, long-term sequestrant use can impact absorption of vitamins and other medications. BSM can also be managed with a low-fat diet, which is cost-effective and can reduce the amount of bile secreted. Nurses should provide patient education to ensure adherence and safe use.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

BACKGROUND & AIMS

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

METHODS

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator, and outcome questions were developed through an iterative process and were voted on by a group of specialists.

RESULTS

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy, or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea, and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review, and reinvestigation for patients whose symptoms persist despite BAST.

CONCLUSIONS

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Canadian Association of Gastroenterology Clinical Practice Guideline on the Management of Bile Acid Diarrhea

Background and Aims

Chronic diarrhea affects about 5% of the population overall. Altered bile acid metabolism is a common but frequently undiagnosed cause.

Methods

We performed a systematic search of publication databases for studies of assessment and management of bile acid diarrhea (BAD). The certainty (quality) of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Patient population, intervention, comparator and outcome questions were developed through an iterative process and were voted on by a group of specialists.

Results

The certainty of evidence was generally rated as very low. Therefore, 16 of 17 recommendations are conditional. In patients with chronic diarrhea, consideration of risk factors (terminal ileal resection, cholecystectomy or abdominal radiotherapy), but not additional symptoms, was recommended for identification of patients with possible BAD. The group suggested testing using ⁷⁵selenium homocholic acid taurine (where available) or 7α-hydroxy-4-cholesten-3-one, including patients with irritable bowel syndrome with diarrhea, functional diarrhea and Crohn's disease without inflammation. Testing was suggested over empiric bile acid sequestrant therapy (BAST). Once remediable causes are managed, the group suggested cholestyramine as initial therapy, with alternate BAST when tolerability is an issue. The group suggested against BAST for patients with extensive ileal Crohn's disease or resection and suggested alternative antidiarrheal agents if BAST is not tolerated. Maintenance BAST should be given at the lowest effective dose, with a trial of intermittent, on-demand administration, concurrent medication review and reinvestigation for patients whose symptoms persist despite BAST.

Conclusions

Based on a systematic review, BAD should be considered for patients with chronic diarrhea. For patients with positive results from tests for BAD, a trial of BAST, initially with cholestyramine, is suggested.

Methods for diagnosing bile acid malabsorption: a systematic review

BACKGROUND

Bile acid malabsorption (BAM) and bile acid-related diarrhea represent an under-recognized cause of chronic diarrhea mainly because of limited guidance on appropriate diagnostic and laboratory tests. We aimed to perform a systematic review of the literature in order to identify and compare the diagnostic accuracy of different diagnostic methods for patients with BAM, despite a proven gold standard test is still lacking.

METHODS

A PubMed literature review and a manual search were carried out. Relevant full papers, evaluating the diagnostic accuracy of different methods for BAM, were assessed. Available data were analyzed to estimate the sensitivity and specificity of each published test.

RESULTS

Overall, more than one test was considered in published papers on BAM. The search strategy retrieved 574 articles; of these, only 16 were full papers (with a total of 2.332 patients) included in the final review. Specifically, n = 8 studies used ⁷⁵Selenium-homotaurocholic-acid-test (⁷⁵SeHCAT) with a < 10% retention threshold; n = 8 studies evaluated fasting serum 7-α-hydroxy-4-cholesten-3-one (C4); n = 3 studies involved total fecal bile acid (BA) excretion over 48 h; n = 4 studies assessed fibroblast growth factor 19 (FGF19). ⁷⁵SeHCAT showed an average sensitivity and specificity of 87.32 and 93.2%, respectively, followed by serum C4 (85.2 and 71.1%) and total fecal BA (66.6 and 79.3%). Fasting serum FGF19 had the lowest sensitivity and specificity (63.8 and 72.3%). All the extracted data were associated with substantial heterogeneity.

CONCLUSIONS

Our systematic review indicates that ⁷⁵SeHCAT has the highest diagnostic accuracy for BAM, followed by serum C4 assay. The diagnostic yield of fecal BA and FGF19 assays is still under investigation. Our review reinforces the need for novel biomarkers aimed to an objective detection of BAM and therefore improving the management of this condition.

Block copolymers as bile salt sequestrants: intriguing structures formed in a mixture of an oppositely charged amphiphilic block copolymer and bile salt

To study the formation and characterize the structure of mixed complexes of oppositely charged block copolymers and surfactants are of great significance for practical applications, e.g., in drug carrier formulations that are based on electrostatically assisted assembly. In this context, biocompatible block copolymers and biosurfactants (like bile salts) are particularly interesting. In this work, we report on the co-assembly in dilute aqueous solution between a cationic poly(N-isopropyl acryl amide) (PNIPAM) diblock copolymer and the oppositely charged bile salt surfactant sodium deoxycholate at ambient temperature. The cryogenic transmission electron microscopy (cryo-TEM) experiments revealed the co-existence of two types of co-assembled complexes of radically different morphology and inner structure. They are formed mainly as a result of the electrostatic attraction between the positively charged copolymer blocks and bile salt anions and highlight the potential of using linear amphiphilic block copolymers as bile salt sequestrants in the treatment of bile acid malabsorption and hypercholesterolemia. The first complex of globular morphology has a coacervate core of deoxycholate anions and charged copolymer blocks surrounded by a PNIPAM corona. The second complex has an intriguing tape-like supramolecular morphology of several micrometer in length that is striped in the direction of the long axis. A model is presented in which the stretched cationic blocks of several block copolymers interact electrostatically with the bile salt molecules that are associated to form a zipper-like structure. The tape is covered on both sides by the PNIPAM chains that stabilize the overall complex in solution. In addition to cryo-TEM, the mixed system was investigated in a range of molar charge fractions at a constant copolymer concentration by static light scattering, small angle X-ray scattering, and electrophoretic mobility measurements.

Clinical evaluation and treatment of chronic bowel symptoms following cancer in the colon and pelvic organs

Background: Chronic gastrointestinal symptoms are common among patients surviving surgery and/or radio-/chemotherapy for cancer in the pelvic organs. However, little is known about the pathophysiology behind symptoms or the effect of treatment. The aim of the present study was to present the results of clinical evaluation and treatment of patients with chronic bowel symptoms after treatment for cancer in the colon or pelvic organs. Material and methods: All patients referred to our department of gastroenterology between May 2016 and June 2018 with chronic bowel symptoms after treatment for cancer in the colon or pelvic organs were prospectively evaluated. Results: In total, 60 patients had been referred. The patients were treated for cancer in the right colon (n = 31), sigmoid colon (n = 1), rectum (n = 14), anal canal (n = 4), cervix uteri (n = 5), corpus uteri (n = 2), ovary (n = 2), and prostate (n = 1). The median time from cancer treatment to referral was 5.5 (range 1-36) years. Symptoms mainly included frequent bowel movements (65%), loose stools (87%), urgency for defecation (57%), and fecal incontinence (50%). A specific cause of bowel dysfunction was found in 48 (80%) of the patients and 21 (35%) had more than one cause of bowel symptoms. Bile acid malabsorption was present in 35 patients and small intestinal bacterial overgrowth was detected in 32. Treatment included bile acid sequestrants (n = 36), antibiotics (n = 33), loperamide (n = 21), and dietary intervention (n = 20). Major improvement in bowel symptoms was reported by 23 (38%) patients, while another 27 (45%) reported some improvement. Conclusion: Most patients with chronic bowel symptoms following cancer in the colon or pelvic organs will benefit from expert clinical evaluation and targeted treatment.