Modern Management of Irritable Bowel Syndrome: More Than Motility

Gut Microbiota Manipulation in Irritable Bowel Syndrome

Increased knowledge suggests that disturbed gut microbiota, termed dysbiosis, might promote the development of irritable bowel syndrome (IBS) symptoms. Accordingly, gut microbiota manipulation has evolved in the last decade as a novel treatment strategy in order to improve IBS symptoms. In using different approaches, dietary management stands first in line, including dietary fiber supplements, prebiotics, and probiotics that are shown to change the composition of gut microbiota, fecal short-chain fatty acids and enteroendocrine cells densities and improve IBS symptoms. However, the exact mixture of beneficial bacteria for each individual remains to be identified. Prescribing nonabsorbable antibiotics still needs confirmation, although using rifaximin has been approved for diarrhea-predominant IBS. Fecal microbiota transplantation (FMT) has recently gained a lot of attention, and five out of seven placebo-controlled trials investigating FMT in IBS obtain promising results regarding symptom reduction and gut microbiota manipulation. However, more data, including larger cohorts and studying long-term effects, are needed before FMT can be regarded as a treatment for IBS in clinical practice.

Magnesium Oxide in Constipation

Magnesium oxide has been widely used as a laxative for many years in East Asia, yet its prescription has largely been based on empirical knowledge. In recent years, several new laxatives have been developed, which has led to a resurgence in interest and increased scientific evidence surrounding the use of magnesium oxide, which is convenient to administer, of low cost, and safe. Despite these advantages, emerging clinical evidence indicates that the use of magnesium oxide should take account of the most appropriate dose, the serum concentration, drug-drug interactions, and the potential for side effects, especially in the elderly and in patients with renal impairment. The aim of this review is to evaluate the evidence base for the clinical use of magnesium oxide for treating constipation and provide a pragmatic guide to its advantages and disadvantages.

Efficacy and Safety of Probiotics in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis

Background

Irritable bowel syndrome is a functional gastrointestinal disease. Evidence has suggested that probiotics may benefit IBS symptoms. However, clinical trials remain conflicting.

Aims

To implement a systematic review and meta-analysis of clinical trials regarding the efficacy and safety of probiotics for IBS patients.

Methods

We searched for relevant trials in Medline(1966 to Jan 2019), Embase(1974 to Jan 2019), the Cochrane Central Register of Controlled Trials(up to Jan 2019), the ClinicalTrials.gov trials register(up to Jan 2019), and Chinese Biomedical Literature Database(1978 to Jan 2019). Risk ratio (RR) and a 95% confidence interval (CI) were calculated for dichotomous outcomes. Standardized mean difference (SMD) and 95% CI were calculated for continuous outcomes.

Results

A total of 59 studies, including 6,761 patients, were obtained. The RR of the improvement or response with probiotics versus placebo was 1.52 (95% CI 1.32-1.76), with significant heterogeneity (I² = 71%, P < 0.001). The SMD of Probiotics in improving global IBS symptoms vs. Placebo was -1.8(95% CI -0.30 to -0.06), with significant heterogeneity (I² = 65%, P < 0.001). It was impossible to draw a determinate conclusion. However, there were differences in subgroup analyses of probiotics type, dose, treatment duration, and geographic position. Probiotics seem to be safe by the analysis of adverse events(RR = 1.07; 95% CI 0.92-1.24; I² = 0, P = 0.83).

Conclusion

Probiotics are effective and safe for IBS patients. Single probiotics with a higher dose (daily dose of probiotics ≥10¹⁰) and shorter duration (< 8 weeks) seem to be a better choice, but it still needs more trials to prove it.

Prevalence and impact of self-reported irritable bowel symptoms in the general population

Background and aims

The symptom-based diagnostic criteria for irritable bowel syndrome (IBS) have recently been revised in the Rome IV consensus. On the other hand, with rising public awareness of IBS, self-diagnosis and self-management is also increasing. We compared the prevalence and impact of Rome IV-based IBS vs self-diagnosed IBS in the general population.

Methods

An internet panel filled out an online survey on bowel symptoms and their impact on health care utilization and daily activities.

Results

A representative internet panel of 1012 individuals completed the online survey. Bowel symptoms were present in 68.6% of the population. Of these, 21% consulted a physician for these symptoms in the last year and 42% earlier. Rome IV IBS criteria were fulfilled by 5.5%, and these were younger and more likely to be female. In this subset, 37% had consulted a physician for IBS symptoms in the preceding year and 29% had done so earlier. A colonoscopy had been performed in 22%. Based on a brief description, 17.6% of the population self-identified as suffering from IBS (p < 0.001 compared to Rome IV IBS prevalence), and these were more likely to be female. Concordance with the Rome IV criteria was only 25%, but except for a lower reporting of pain, the symptom pattern, severity, impact on daily life, inability to work and health care utilization were similar to the Rome IV group. A total of 134 days of absence from work were attributed to bowel symptoms in those self-reporting with IBS.

Conclusion

In the general population, bowel symptoms are highly prevalent, and the self-reported "IBS" is three times more prevalent than according to Rome IV criteria. Self-reported IBS is associated with a similar impact on health care utilization and quality of life but a higher impact on absence from work.

Linaclotide increases cecal pH, accelerates colonic transit, and increases colonic motility in irritable bowel syndrome with constipation

BACKGROUND

Linaclotide is efficacious in the management of irritable bowel syndrome with constipation (IBS-C), yet relatively little is known regarding its effect on human gastrointestinal physiology. The primary aim of the study was to examine the effect of linaclotide on change in pH across the ileocecal junction (ICJ), a proposed measure of cecal fermentation, and its relationship to symptoms and quality of life (QoL) in IBS-C.

METHODS

A total of 13 participants with Rome III IBS-C underwent a standardized wireless motility capsule (WMC). Stool consistency was measured using the Bristol stool form scale (BSFS) and frequency with spontaneous bowel movements (SBM). Gastrointestinal symptoms and QoL were assessed using validated questionnaires. The WMC and questionnaires were repeated after 28 days of linaclotide 290 g po od.

KEY RESULTS

Linaclotide reduced the change in pH across the ICJ (-2.4 ± 0.2 vs -2.1 ± 0.4, P = 0.01) as a function of a relative alkalinization of the cecum (5.2 ± 0.2 vs 5.5 ± 0.3, P = 0.02). Linaclotide accelerated colonic transit time (2650 minutes (2171-4038) vs. 1757 (112-3011), P = 0.02), increased colonic log motility index (15 ± 1.8 vs. 16.5 ± 1.8, P = 0.004) but had no effect of gastric emptying or small bowel transit. Change in pH across the ICJ correlated with improvement in symptom intensity, unpleasantness, and visceral sensitivity index (r = 0.62, P = 0.03, r = 0.63, P = 0.02, r = 0.62, P = 0.02) and with increases in BSFS type and SBM (r = 0.9, P < 0.0001, r = 0.6, P = 0.02).

CONCLUSIONS & INFERENCES

Linaclotide's effects are confined to the colon where it increases cecal pH, potentially representing a reduction in cecal fermentation and accelerates colonic motility.

Long-term impact of the low-FODMAP diet on gastrointestinal symptoms, dietary intake, patient acceptability, and healthcare utilization in irritable bowel syndrome

BACKGROUND

The low-FODMAP diet is a frequently used treatment for irritable bowel syndrome (IBS). Most research has focused on short-term FODMAP restriction; however, guidelines recommend that high-FODMAP foods are reintroduced to individual tolerance. This study aimed to assess the long-term effectiveness of the low-FODMAP diet following FODMAP reintroduction in IBS patients.

METHODS

Patients with IBS were prospectively recruited to a questionnaire study following completion of dietitian-led low-FODMAP education. At baseline and following FODMAP restriction (short term) only, gastrointestinal symptoms were measured as part of routine clinical care. Following FODMAP reintroduction, (long term), symptoms, dietary intake, acceptability, food-related quality of life (QOL), and healthcare utilization were assessed. Data were reported for patients who continued long-term FODMAP restriction (adapted FODMAP) and/or returned to a habitual diet (habitual).

KEY RESULTS

Of 103 patients, satisfactory relief of symptoms was reported in 12% at baseline, 61% at short-term follow-up, and 57% at long-term follow-up. At long-term follow-up, 84 (82%) patients continued an 'adapted FODMAP' diet (total FODMAP intake mean 20.6, SD 14.9 g/d) compared with 19 (18%) of patients following a 'habitual' diet (29.4, SD 22.9 g/d, P=.039). Nutritional adequacy was not compromised for either group. The 'adapted FODMAP' group reported the diet cost significantly more than the 'habitual' group (P<.001) and affected social eating (P<.01) but there was no effect on food-related QOL. Healthcare utilization was similar between both groups.

CONCLUSION AND INFERENCES

Low-FODMAP education is effective for long-term IBS management, enables a nutritionally adequate diet, and is broadly acceptable to patients.

Targeting Small Bowel Receptors to Treat Constipation and Diarrhea

BACKGROUND

The options for the treatment of diarrhea and constipation are evolving as emerging therapies target small bowel receptors. The goal of this review is to discuss small bowel receptors involved in intestinal absorption, secretion, and motility. The review highlights therapies already approved or currently being studied for the modulation of these receptors.

METHODS

The articles cited in this review focus on the molecular level of pathways involved in diarrhea and constipation, and highlight the respective pharmacotherapies.

RESULTS

The majority of the studies in the current literature investigate the effects of both the small and large intestine receptors on diarrhea and constipation. There are fewer studies that isolate the effects of these receptors solely on the small bowel, and focusing more on the receptors found distinctly in the small intestine may be an area of interest for future studies as this can inspire more targeted therapies.

New insights into the pathogenesis and treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders (FGID), characterized by abdominal pain and a change in stool form that cannot be explained by structural abnormalities. Its prevalence ranges from 9 to 23% of the worldwide population. The pathophysiology of IBS is diverse and not well understood. Biopsychosocial concept assumes that the disease is a product of psychosocial factors and altered at multiple levels of gut physiology interactions. Some aetiological factors have been identified, yet. One of the most important is the disruption of brain-gut mutual communication that leads to visceral hypersensitivity. Also genetic and epigenetic factors are involved. Chronic stress may predispose to IBS as well as exacerbate its symptoms. Both quantitative and qualitative disorders of the gut microbiota are observed. There is also a relationship between the IBS symptoms and the intake of a specific type of food products. In the diarrhoea type of IBS the role of previous gastrointestinal infection is demonstrated. Recent studies have suggested that visceral hypersensitivity in patients with IBS may be secondary to the activation of the immune cells and low-grade inflammation. Clinical symptoms of IBS include abdominal pain and change in bowel habits as well as somatic and psychiatric comorbidities. IBS is diagnosed on the basis of Rome Diagnostic Criteria. Recently, their newest version (Rome IV) has been presented. The aim of this review is to summarize the past decade progress in IBS diagnosis, main pathophysiological aspects and therapeutic management strategy.

Pharmacological Approach for Managing Pain in Irritable Bowel Syndrome: A Review Article

Context

Visceral pain is a leading symptom for patients with irritable bowel syndrome (IBS) that affects 10% - 20 % of the world population. Conventional pharmacological treatments to manage IBS-related visceral pain is unsatisfactory. Recently, medications have emerged to treat IBS patients by targeting the gastrointestinal (GI) tract and peripheral nerves to alleviate visceral pain while avoiding adverse effects on the central nervous system (CNS). Several investigational drugs for IBS also target the periphery with minimal CNS effects.

Evidence of Acquisition

In this paper, reputable internet databases from 1960 - 2016 were searched including Pubmed and ClinicalTrials.org, and 97 original articles analyzed. Search was performed based on the following keywords and combinations: irritable bowel syndrome, clinical trial, pain, visceral pain, narcotics, opioid, chloride channel, neuropathy, primary afferent, intestine, microbiota, gut barrier, inflammation, diarrhea, constipation, serotonin, visceral hypersensitivity, nociceptor, sensitization, hyperalgesia.

Results

Certain conventional pain managing drugs do not effectively improve IBS symptoms, including NSAIDs, acetaminophen, aspirin, and various narcotics. Anxiolytic and antidepressant drugs (Benzodiazepines, TCAs, SSRI and SNRI) can attenuate pain in IBS patients with relevant comorbidities. Clonidine, gabapentin and pregabalin can moderately improve IBS symptoms. Lubiprostone relieves constipation predominant IBS (IBS-C) while loperamide improves diarrhea predominant IBS (IBS-D). Alosetron, granisetron and ondansetron can generally treat pain in IBS-D patients, of which alosetron needs to be used with caution due to cardiovascular toxicity. The optimal drugs for managing pain in IBS-D and IBS-C appear to be eluxadoline and linaclotide, respectively, both of which target peripheral GI tract.

Conclusions

Conventional pain managing drugs are in general not suitable for treating IBS pain. Medications that target the GI tract and peripheral nerves have better therapeutic profiles by limiting adverse CNS effects.