Effect of a tricyclic antidepressant on small intestinal motility in health and diarrhea-predominant irritable bowel syndrome

Amitriptyline at Low-Dose and Titrated for Irritable Bowel Syndrome as Second-Line Treatment in primary care (ATLANTIS): a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Most patients with irritable bowel syndrome (IBS) are managed in primary care. When first-line therapies for IBS are ineffective, the UK National Institute for Health and Care Excellence guideline suggests considering low- dose tricyclic antidepressants as second-line treatment, but their effectiveness in primary care is unknown, and they are infrequently prescribed in this setting.

METHODS

This randomised, double-blind, placebo-controlled trial (Amitriptyline at Low-Dose and Titrated for Irritable Bowel Syndrome as Second-Line Treatment [ATLANTIS]) was conducted at 55 general practices in England. Eligible participants were aged 18 years or older, with Rome IV IBS of any subtype, and ongoing symptoms (IBS Severity Scoring System [IBS-SSS] score ≥75 points) despite dietary changes and first-line therapies, a normal full blood count and C-reactive protein, negative coeliac serology, and no evidence of suicidal ideation. Participants were randomly assigned (1:1) to low-dose oral amitriptyline (10 mg once daily) or placebo for 6 months, with dose titration over 3 weeks (up to 30 mg once daily), according to symptoms and tolerability. Participants, their general practitioners, investigators, and the analysis team were all masked to allocation throughout the trial. The primary outcome was the IBS-SSS score at 6 months. Effectiveness analyses were according to intention-to-treat; safety analyses were on all participants who took at least one dose of the trial medication. This trial is registered with the ISRCTN Registry (ISRCTN48075063) and is closed to new participants.

FINDINGS

Between Oct 18, 2019, and April 11, 2022, 463 participants (mean age 48·5 years [SD 16·1], 315 [68%] female to 148 [32%] male) were randomly allocated to receive low-dose amitriptyline (232) or placebo (231). Intention-to-treat analysis of the primary outcome showed a significant difference in favour of low-dose amitriptyline in IBS-SSS score between groups at 6 months (-27·0, 95% CI -46·9 to -7·10; p=0·0079). 46 (20%) participants discontinued low-dose amitriptyline (30 [13%] due to adverse events), and 59 (26%) discontinued placebo (20 [9%] due to adverse events) before 6 months. There were five serious adverse reactions (two in the amitriptyline group and three in the placebo group), and five serious adverse events unrelated to trial medication.

INTERPRETATION

To our knowledge, this is the largest trial of a tricyclic antidepressant in IBS ever conducted. Titrated low-dose amitriptyline was superior to placebo as a second-line treatment for IBS in primary care across multiple outcomes, and was safe and well tolerated. General practitioners should offer low-dose amitriptyline to patients with IBS whose symptoms do not improve with first-line therapies, with appropriate support to guide patient-led dose titration, such as the self-titration document developed for this trial.

FUNDING

National Institute for Health and Care Research Health Technology Assessment Programme (grant reference 16/162/01).

Irritable bowel syndrome and mental health comorbidity - approach to multidisciplinary management

Irritable bowel syndrome (IBS) affects 5-10% of the global population. Up to one-third of people with IBS also experience anxiety or depression. Gastrointestinal and psychological symptoms both drive health-care use in people with IBS, but psychological comorbidity seems to be more important for long-term quality of life. An integrated care approach that addresses gastrointestinal symptoms with nutrition and brain-gut behaviour therapies is considered the gold standard. However, best practice for the treatment of individuals with IBS who have a comorbid psychological condition is unclear. Given the rising prevalence of mental health disorders, discussion of the challenges of implementing therapy for people with IBS and anxiety and depression is critical. In this Review, we draw upon our expertise in gastroenterology, nutrition science and psychology to highlight common challenges that arise when managing patients with IBS and co-occurring anxiety and depression, and provide recommendations for tailoring clinical assessment and treatment. We provide best practice recommendations, including dietary and behavioural interventions that could be applied by non-specialists and clinicians working outside an integrated care model.

Non-pharmacological strategies to treat irritable bowel syndrome: 2022 update

Irritable bowel syndrome (IBS) is a chronic functional disorder characterized by abdominal pain associated with changes in stool frequency or form, in absence of organic disease. The treatment of IBS is often challenging and should be individually adjusted according to the prevalent symptomatology. Pharmacological treatment for IBS with diarrhea includes peripheral opioid agonists, bile acid sequestrants and antibiotics, while IBS with constipation can be treated with soluble fibers, osmotic agents or prokinetics. In case of abdominal pain, the available pharmacological options are antispasmodics, peripheral opioid agonists or antidepressants. Along with pharmacotherapy, non-pharmacological interventions should be considered as they can play an important role in symptom control. The first-line approach includes lifestyle modifications and dietary advice. Microbiota manipulation through probiotics, prebiotics and symbiotics is a widely used strategy, although the evidence upon the most effective among these in specific IBS subtypes is still unclear. Fecal microbiota transplantation is still in experimental phase for IBS, but it is giving promising results. Psychological therapies may be effective in patients with IBS, despite their application can be limited by long duration, high costs and poor patient's acceptance. Alternative medicine approaches, such as acupuncture, body relaxation techniques, dietary supplements or Chinese herbs, have been proposed; however, the evidence upon their efficacy and safety is still controversial.

Amitriptyline at low-dose and titrated for irritable bowel syndrome as second-line treatment (The ATLANTIS trial): protocol for a randomised double-blind placebo-controlled trial in primary care

Background

Irritable bowel syndrome (IBS) is a common functional bowel disorder that has a considerable impact on patient quality of life and substantial societal and health care resource costs. Current treatments are often ineffective. Tricyclic antidepressants have shown promise in secondary care populations but their effectiveness in a primary care setting remains unclear.

Methods

ATLANTIS is a randomised, multi-centre, parallel-group, two-arm, double-blind, placebo-controlled trial of low-dose amitriptyline as a second-line treatment for IBS in primary care. Participants will be invited by letter, or recruited opportunistically, from general practices in three regions of England (West Yorkshire, Wessex, and West of England) and screened for eligibility. A total of 518 adult patients with IBS, who are symptomatic despite first-line therapies, will be randomised 1:1 to amitriptyline or identical placebo for 6 months. Treatment will commence at a dose of 10 mg (or one placebo tablet) daily at night, with dose titration up to a maximum of 30 mg at night, depending on side effects and response to treatment. Participant-reported assessments will be conducted at baseline and 3, 6, and 12 months post-randomisation. The primary objective is to determine the effectiveness of amitriptyline, compared with placebo, in improving participant-reported global symptoms of IBS at 6 months (using the IBS Severity Scoring System). Secondary outcomes include relief of IBS symptoms, effect on IBS-associated somatic symptoms (Patient Health Questionnaire-12), anxiety and depression (Hospital Anxiety and Depression Scale), ability to work and participate in other activities (Work and Social Adjustment Scale), acceptability and tolerability of treatment, self-reported health care use, health-related quality of life (EQ-5D-3L), and cost-effectiveness. A nested, qualitative study will explore patient and general practitioner experiences of treatments and trial participation, including acceptability, adherence, unanticipated effects, and implications for wider use of amitriptyline for IBS in primary care.

Discussion

Determining the clinical and cost-effectiveness of low-dose amitriptyline as a second-line treatment for IBS in primary care will provide robust evidence to inform management decisions.

Trial registration

ISRCTN ISRCTN48075063 . Registered on 7th June 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06492-6.

Inhibition of TRPC4 channel activity in colonic myocytes by tricyclic antidepressants disrupts colonic motility causing constipation

Tricyclic antidepressants (TCAs) have been used to treat depression and were recently approved for treating irritable bowel syndrome (IBS) patients with severe or refractory IBS symptoms. However, the molecular mechanism of TCA action in the gastrointestinal (GI) tract remains poorly understood. Transient receptor potential channel canonical type 4 (TRPC4), which is a Ca²⁺‐permeable nonselective cation channel, is a critical regulator of GI excitability. Herein, we investigated whether TCA modulates TRPC4 channel activity and which mechanism in colonic myocytes consequently causes constipation. To prove the clinical benefit in patients with diarrhoea caused by TCA treatment, we performed mechanical tension recording of repetitive motor pattern (RMP) in segment, electric field stimulation (EFS)‐induced and spontaneous contractions in isolated muscle strips. From these recordings, we observed that all TCA compounds significantly inhibited contractions of colonic motility in human. To determine the contribution of TRPC4 to colonic motility, we measured the electrical activity of heterologous or endogenous TRPC4 by TCAs using the patch clamp technique in HEK293 cells and murine colonic myocytes. In TRPC4‐overexpressed HEK cells, we observed TCA‐evoked direct inhibition of TRPC4. Compared with TRPC4‐knockout mice, we identified that muscarinic cationic current (mI_cat) was suppressed through TRPC4 inhibition by TCA in isolated murine colonic myocytes. Collectively, we suggest that TCA action is responsible for the inhibition of TRPC4 channels in colonic myocytes, ultimately causing constipation. These findings provide clinical insights into abnormal intestinal motility and medical interventions aimed at IBS therapy.

Targeting the Gut Microbiota to Relieve the Symptoms of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common, chronic, functional disorder with a large impact on world population. Its pathophysiology is not completely revealed; however, it is certain that dysregulation of the bidirectional communications between the central nervous system (CNS) and the gut leads to motility disturbances, visceral hypersensitivity, and altered CNS processing characterized by differences in brain structure, connectivity and functional responsiveness. Emerging evidence suggests that gut microbiota exerts a marked influence on the host during health and disease. Gut microbiome disturbances can be also important for development of IBS symptoms and its modulation efficiently contributes to the therapy. In this work, we review the current knowledge about the IBS therapy, the role of gut microbiota in pathogenesis of IBS, and we discuss that its targeting may have significant impact on the effectiveness of IBS therapy.

Medical Therapies for Diarrhea-Predominant Irritable Bowel Syndrome

Diarrhea-predominant irritable bowel syndrome is a common functional gastrointestinal disorder that manifests with abdominal pain and diarrheal bowel patterns, without structural explanation. Diarrhea-predominant irritable bowel syndrome is a heterogeneous condition resulting from diverse pathophysiologic processes. Treatment strategies with varied mechanisms of action are beneficial in its management. The clinician must become familiar with a multi-dimensional approach to irritable bowel syndrome. The 3 approved medications are central to disease management. Effective treatment uses off-label medications and emerging therapies and a growing number of over-the-counter and supplemental agents to optimize symptom improvement for the patient with diarrhea-predominant irritable bowel syndrome.

Gastrointestinal symptoms following treatment for anorexia nervosa: A systematic literature review

OBJECTIVE

Gastrointestinal (GI) disturbances are a frequent and burdensome experience for patients with anorexia nervosa (AN). How GI symptoms respond to current interventions is not well characterized, yet is critical to facilitate treatment success, and to inform the development of new treatments for AN. Therefore, the aim of this systematic review was to identify which treatments are effective in improving GI symptoms in patients with AN.

METHOD

A systematic search for studies of AN treatments measuring GI symptoms pre- and post-treatment was conducted in May 2020 (PROSPERO ID: CRD42020181328). After removal of duplicates, title and abstracts of 3,370 studies were screened. Methodological quality was assessed using National Institute of Health Quality Assessment Tool.

RESULTS

Following full-text screening, 13 studies (12 observational studies and 1 randomized double-blind placebo-controlled trial) with 401 participants met eligibility criteria and were included. All observational studies included a component of nutritional rehabilitation, with half (n = 6) involving concurrent psychological treatment. The randomized controlled trial reported a drug therapy. Eleven studies reported an improvement in all (n = 6) or at least one (n = 5) patient-reported GI symptom following treatment. Two studies reported no change. Methodological quality was fair or poor across all studies.

DISCUSSION

This is the first systematic review to synthesize available evidence on the trajectory of patient-reported GI symptoms from commencement to end of treatment for AN. The results suggest that most studies showed improvement in one or more GI symptom in response to current treatments. Future therapeutic approaches should consider GI symptoms within their design for optimal treatment adherence and outcomes.

Common mental disorders in irritable bowel syndrome: pathophysiology, management, and considerations for future randomised controlled trials

The frequent co-occurrence of irritable bowel syndrome and the common mental disorders of anxiety and depression is well established. A range of biological and psychosocial disease mechanisms are common to both disorders, many of which contribute to a dysregulated gut-brain axis. Clinical and subthreshold psychological comorbidity adds to the functional impairment and disease burden in individuals with irritable bowel syndrome. Progress is being made with regard to understanding irritable bowel syndrome in the clinical setting from a biopsychosocial perspective. However, until now, most trials of irritable bowel syndrome treatment still consider the disease as a gut disorder in isolation, which leaves major gaps in knowledge about disease-disease interactions and treatment outcomes in irritable bowel syndrome. In this Viewpoint, we review the epidemiology, pathophysiology, and management of anxiety and depression in individuals with irritable bowel syndrome. We also provide methodological recommendations for future randomised controlled trials and outline guidance for research that better incorporates psychiatric comorbidity into its design, with a view to improve treatment outcomes for individuals with irritable bowel syndrome.

Systematic review and network meta-analysis: efficacy of drugs for functional dyspepsia

BACKGROUND

Functional dyspepsia (FD) is a relapsing and remitting condition affecting between 5% and 10% of people. Efficacious therapies are available, but their relative efficacy is unknown.

AIM

To perform a systematic review with network meta-analysis to resolve this uncertainty.

METHODS

We searched the medical literature through July 2020 for randomised controlled trials (RCTs) assessing efficacy of drugs for adults with FD, compared with each other, or placebo. Trials reported a dichotomous assessment of symptom status after completion of therapy. We pooled data using a random effects model. Efficacy was reported as a pooled relative risk (RR) of remaining symptomatic with a 95% confidence interval (CI) to summarise efficacy of each comparison tested. Relative ranking was assessed with surface under the cumulative ranking curve (SUCRA) probabilities.

RESULTS

We identified 71 eligible RCTs (19 243 participants). Tricyclic antidepressants (TCAs) were ranked second for efficacy (RR of remaining symptomatic = 0.71; 95% CI 0.58-0.87, SUCRA 0.87), and first when only low risk of bias trials were included. Most RCTs that used TCAs recruited patients who were refractory to other drugs included in the network. Although sulpiride or levosulpiride were ranked first for efficacy (RR = 0.49; 95% CI 0.36-0.69, SUCRA 0.99), trial quality was low and only 86 patients received active therapy. TCAs were more likely to cause adverse events than placebo.

CONCLUSIONS

TCAs, histamine-₂ receptor antagonists, standard- and low-dose proton pump inhibitors, sulpiride or levosulpiride, itopride and acotiamide were all more efficacious than placebo for FD.

Irritable bowel syndrome

Irritable bowel syndrome is a functional gastrointestinal disorder with symptoms including abdominal pain associated with a change in stool form or frequency. The condition affects between 5% and 10% of otherwise healthy individuals at any one point in time and, in most people, runs a relapsing and remitting course. The best described risk factor is acute enteric infection, but irritable bowel syndrome is also more common in people with psychological comorbidity and in young adult women than in the rest of the general population. The pathophysiology of irritable bowel syndrome is incompletely understood, but it is well established that there is disordered communication between the gut and the brain, leading to motility disturbances, visceral hypersensitivity, and altered CNS processing. Other less reproducible mechanisms might include genetic associations, alterations in gastrointestinal microbiota, and disturbances in mucosal and immune function. In most people, diagnosis can be made on the basis of clinical history with limited and judicious use of investigations, unless alarm symptoms such as weight loss or rectal bleeding are present, or there is a family history of inflammatory bowel disease or coeliac disease. Once the diagnosis is made, an empathetic approach is key and can improve quality of life and symptoms, and reduce health-care expenditure. The mainstays of treatment include patient education about the condition, dietary changes, soluble fibre, and antispasmodic drugs. Other treatments tend to be reserved for people with severe symptoms and include central neuromodulators, intestinal secretagogues, drugs acting on opioid or 5-HT receptors, or minimally absorbed antibiotics (all of which are selected according to predominant bowel habit), as well as psychological therapies. Increased understanding of the pathophysiology of irritable bowel syndrome in the past 10 years has led to a healthy pipeline of novel drugs in development.

Depression and Structural Factors Are Associated With Symptoms in Patients of Irritable Bowel Syndrome With Diarrhea

Background/Aims

A strong correlation between depression and irritable bowel syndrome with diarrhea (IBS-D) has been identified. The aim of this study is to identify the correlations among depression, structural factors, gastrointestinal (GI) and extra-GI symptoms, and efficacy of neuromodulators in patients with IBS-D.

Methods

Patients meeting the Rome III Diagnostic Criteria for IBS-D were enrolled. The intestinal symptoms and psychological states were evaluated using IBS-specific symptom questionnaires and Hamilton Depression Rating Scale.

Results

In total, 410 patients with IBS-D were enrolled, 28.8% (118/410) had comorbid depression. Patients with depression did not readily experience improvement in abdominal pain/discomfort after defecation, and had a higher prevalence of passing mucus, overlapping functional dyspepsia, and extra-GI symptoms. The structural factor “mental disorders” significantly correlated with main bowel symptom score and degree of pre-defecation abdominal pain/discomfort. No structural factor significantly correlated with bowel movements or stool form. Patients who had passing mucus, overlapping functional dyspepsia and extra-GI painful symptoms have higher score of “anxiety/somatization.” Patients with sexual dysfunction have higher score of “retardation symptoms.” In total, 28.3% of patients with IBS-D were prescribed neuromodulators. Baseline scores of “anxiety/somatization” and “retardation symptoms” positively correlated with improvement of diarrhea after paroxetine, and “sleep disturbances” positively correlated with improvement of abdominal pain/discomfort and diarrhea after mirtazapine.

Conclusions

Comorbid depression and higher scores of structural factors might aggravate GI and extra-GI symptoms other than bowel movements and stool form. Structural factors of Hamilton Depression Rating Scale correlated with efficacy of paroxetine and mirtazapine in patients with IBS-D.

Knowledge and practices of primary care physicians or general practitioners treating post-infectious Irritable Bowel Syndrome

Background

Post-infectious Irritable Bowel Syndrome (PI-IBS) is a functional bowel disorder which has significant impacts to a patient’s quality of life. No IBS-specific biomarker or treatment regimen for PI-IBS currently exists, therefore understanding practice patterns and variance is of interest.

Methods

This online survey of primary care physicians and general practitioners in the USA aimed to understand the knowledge and treatment of PI-IBS within the physician’s current practice. Summary statistics are provided with a commentary on implications for practices and treatment of PI-IBS.

Results

Most physician survey respondents (n = 50) were aware of PI-IBS, but less than half discussed this condition as a possible outcome in their patients with a recent gastrointestinal infection. Most physicians indicated that they would treat the patients themselves with a focus on managing IBS through different treatment modalities based on severity. Treatment for PI-IBS followed IBS recommendations, but most physicians also prescribed a probiotic for therapy. Physicians estimated that 4 out of 10 patients who develop PI-IBS will have life-long symptoms and described significant impacts to their patient’s quality of life. Additionally, physicians estimated a significant financial burden for PI-IBS patients, ranging from $100–1000 (USD) over the course of their illness. Most physicians agreed that they would use a risk score to predict the probability of their patients developing PI-IBS, if available.

Conclusions

While this survey is limited due to sample size, physician knowledge and treatment of PI-IBS was consistent across respondents. Overall, the physicians identified significant impacts to patient’s quality of life due to PI-IBS.

Antidepressants in inflammatory bowel disease

Gut-brain dysregulation has been recognized by the scientific community as being crucial to the understanding of chronic gastrointestinal conditions, and this has translated into the practice of a newly established discipline, psychogastroenterology. Along with psychotherapy, antidepressants (a subtype of central neuromodulators) have been proposed as treatments for gut-brain disorders that might benefit both psychological and gastrointestinal health. Antidepressants have been found to be effective for the treatment of comorbid anxiety and depression, pain and impaired sleep. Although the efficacy of antidepressants is well established in disorders of gut-brain interaction (DGBI), evidence is only now emerging in IBD. This Perspective discusses the use of antidepressants in DGBI and IBD, focusing on how what we have learnt about the role of antidepressants in DGBI could be applied to help optimize the management of IBD.

Effect of Antidepressants and Psychological Therapies in Irritable Bowel Syndrome: An Updated Systematic Review and Meta-Analysis

OBJECTIVES

Irritable bowel syndrome (IBS) is a chronic functional bowel disorder that is thought to be due to a disorder of brain-gut function. Drugs acting centrally, such as antidepressants, and psychological therapies may, therefore, be effective.

METHODS

We updated a previous systematic review and meta-analysis of randomized controlled trials (RCTs). MEDLINE, EMBASE, PsychINFO, and the Cochrane Controlled Trials Register were searched (up to July 2017). Trials recruiting adults with IBS, which compared antidepressants versus placebo, or psychological therapies versus control therapy or "usual management" were eligible. Dichotomous symptom data were pooled to obtain a relative risk (RR) of remaining symptomatic after therapy, with a 95% confidence interval (CI).

RESULTS

The search strategy identified 5316 citations. Fifty-three RCTs, reported in 51 separate articles, were eligible for inclusion: 17 compared antidepressants with placebo, 35 compared psychological therapies with control therapy or "usual management", and one compared both psychological therapy and antidepressants with placebo. Four of the trials of psychological therapies, and one of the RCTs of antidepressants, were identified since our previous meta-analysis. The RR of IBS symptoms not improving with antidepressants versus placebo was 0.66 (95% CI 0.57-0.76), with similar treatment effects for both tricyclic antidepressants and SSRIs, although with heterogeneity between RCTs of the latter (I(2) = 49%, P = 0.07). The RR of symptoms not improving with psychological therapies was 0.69 (95% CI 0.62-0.76). Cognitive behavioral therapy, relaxation therapy, multi-component psychological therapy, hypnotherapy, and dynamic psychotherapy were all beneficial when data from two or more RCTs were pooled. There was significant heterogeneity between studies (I(2) = 69%, P < 0.001) and significant funnel plot asymmetry. There were also issues regarding trial design, including lack of blinding.

CONCLUSIONS

Antidepressants are efficacious in reducing symptoms in IBS patients. Psychological therapies also appear to be effective treatments for IBS, although there are limitations in the quality of the evidence, and treatment effects may be overestimated as a result.

Neuromodulators for Functional Gastrointestinal Disorders (Disorders of Gut-Brain Interaction): A Rome Foundation Working Team Report

BACKGROUND & AIMS

Central neuromodulators (antidepressants, antipsychotics, and other central nervous system-targeted medications) are increasingly used for treatment of functional gastrointestinal disorders (FGIDs), now recognized as disorders of gut-brain interaction. However, the available evidence and guidance for the use of central neuromodulators in these conditions is scanty and incomplete. In this Rome Foundation Working Team report, a multidisciplinary team summarized available research evidence and clinical experience to provide guidance and treatment recommendations.

METHODS

The working team summarized the literature on the pharmacology of central neuromodulators and their effects on gastrointestinal sensorimotor function and conducted an evidence-based review on their use for treating FGID syndromes. Because of the paucity of data for FGIDs, we included data for non-gastrointestinal painful disorders and specific symptoms of pain, nausea, and vomiting. This information was combined into a final document comprising a synthesis of available evidence and recommendations for clinical use guided by the research and clinical experience of the experts on the committee.

RESULTS

The evidence-based review on neuromodulators in FGID, restricted by the limited available controlled trials, was integrated with open-label studies and case series, along with the experience of experts to create recommendations using a consensus (Delphi) approach. Due to the diversity of conditions and complexity of treatment options, specific recommendations were generated for different FGIDs. However, some general recommendations include: (1) low to modest dosages of tricyclic antidepressants provide the most convincing evidence of benefit for treating chronic gastrointestinal pain and painful FGIDs and serotonin noradrenergic reuptake inhibitors can also be recommended, though further studies are needed; (2) augmentation, that is, adding a second treatment (adding quetiapine, aripiprazole, buspirone α2δ ligand agents) is recommended when a single medication is unsuccessful or produces side effects at higher dosages; (3) treatment should be continued for 6-12 months to potentially prevent relapse; and (4) implementation of successful treatment requires effective communication skills to improve patient acceptance and adherence, and to optimize the patient-provider relationship.

CONCLUSIONS

Based on systematic and selectively focused review and the consensus of a multidisciplinary panel, we have provided summary information and guidelines for the use of central neuromodulators in the treatment of chronic gastrointestinal symptoms and FGIDs. Further studies are needed to confirm and refine these recommendations.

Irritable bowel syndrome - from etiopathogenesis to therapy

Irritable bowel syndrome (IBS) is a chronic and relapsing functional gastrointestinal disorder that affects 9-23% of the population across the world. Patients with IBS are often referred to gastroenterology, undergo various investigations, take various medicines, take time off work and have a poor quality of life. The pathophysiology of IBS is not yet completely understood and seems to be multifactorial. Many pathogenetic factors, in various combinations, and not all necessarily present in each patient, can play an important role. Discomfort or abdominal pain relieived by defacation, asociated with a change in stool form, is a typical clinical manifestation of IBS. Many factors, such as emotional stress and eating, may exacerbate the symptoms. A timely diagnosis of IBS is important so that treatment which will provide adequate symptomatic relief (diarrhoea, constipation, pain and boaring) can be introduced. The diagnosis of IBS is not confirmed by a specific test or structural abnormality. It is made using criteria based on clinical symptoms such as Rome criteria, unless the symptoms are thought to be atypical. Today the Rome Criteria IV is the current gold-standard for the diagnoses of IBS. Treatment of patients with IBS requires a multidisciplinary approach. Some patients respond well to non-pharmacological treatment, while others also require pharmacological treatment. This review will provide a summary of pathophysiology, diagnostic criteria and therapies for IBS.

Antidepressants for irritable bowel syndrome-A systematic review

BACKGROUND

According to the multifactorial etiology of Irritable bowel syndrome (IBS), psychological factors play an important role. It is possible that antidepressant therapy may be more effective for patients with IBS. The aim of this study was a systematic review of the best available antidepressant therapies for IBS.

METHODS

The databases Medline, PubMed, EMBASE, and the Cochrane Controlled Trials Register for randomized controlled trials were searched for studies published before September 2016. Meta-analyses, randomized controlled trials, controlled trials, uncontrolled trials, cohort studies, and open-label studies were analyzed.

RESULTS

Of 513 articles, 29 fulfilled the inclusion criteria: 6 meta-analyses, 18 randomized controlled trials, and 5 studies without randomization. In these studies, the efficacy of tricyclics, selective serotonin reuptake inhibitors or serotonin-noradrenaline reuptake inhibitors, were analyzed in IBS. Different interventions were used, though in most studies their effect on global symptom relief in IBS as a primary outcome was investigated. Generally, patients' tolerance of the therapies was good. Only severe adverse events were observed as a result of the nature of the drug.

CONCLUSIONS

Generally, antidepressants improved IBS symptoms. In comparison with placebo, tricyclic therapy for IBS was more effective than selective serotonin reuptake inhibitors. Antidepressants might be an alternative therapy for patients suffering from IBS, especially diarrhea-predominant IBS.

Empirically Supported Use of Psychiatric Medications in Adolescents and Adults with IBD

BACKGROUND

The use of psychotropic medications, particularly antidepressants, is common in patients with inflammatory bowel disease (IBD) in spite of a lack of their robust efficacy in this population. This review provides an overview of the use trends of different classes of antidepressant and anti-anxiety medication and their effects on mood, nervous system function, gastrointestinal physiology and immunity drawing from the literature available in the general population, other medical conditions, and when available, patients with IBD. It also covers the evidence base for the actions, efficacy, and potential complications of antidepressants organized by different classes.

METHODS

We conducted a PubMed search of articles relating the different drug classes probed to the terms above in different populations of interest. All types of articles were accepted including case reports and series, open and randomized trials, reviews, and expert opinion. We also examined the reference lists of the publications found.

RESULTS

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are the most commonly prescribed agents for anxiety and depression in patients with IBD, though their efficacy for these conditions in the general population are mild to moderate at best. SSRIs are generally well tolerated, though at higher doses, they, like most antidepressant classes, can be associated with activation, serotonergic syndrome, and increased suicidal ideation. TCAs have many more serious side effects but have some shown efficacy for functional GI symptoms. A newer class, the serotonin noradrenergic reuptake inhibitors (SNRIs), can be effective for refractory depression, anxiety and chronic pain syndromes with a side effect profile similar to both SSRIs and more mild manifestations of TCAs. Mirtazapine has moderate efficacy for depression if sedation and weight gain side effects are tolerated and some small support for use in nausea and vomiting. Bupropion targets dopamine and noradrenaline reuptake and has moderate efficacy for depression, and some small support for use in fatigue and smoking cessation. Buspirone has an indication for generalized anxiety disorder though studies show only a minimal benefit. It has some growing evidence for use in functional dyspepsia. Most of these agents have physiological effects on the brain, immune system, and gastrointestinal tract (with the exception of bupropion) hence their therapeutic and side effects manifested in these systems.

CONCLUSION

Antidepressant medications are frequently prescribed for depression, anxiety disorders, and chronic pain syndromes, but overall support for their efficacy is modest at best. Psychological interventions have growing support for having much more robust effects without the side effects of antidepressants and should be considered first-line treatment or at least an adjunct to psychotropic medications for these conditions.

Measurement of Gastrointestinal and Colonic Motor Functions in Humans and Animals

Accurately measuring the complex motor behaviors of the gastrointestinal tract has tremendous value for the understanding, diagnosis and treatment of digestive diseases. This review synthesizes the literature regarding current tests that are used in both humans and animals. There remains further opportunity to enhance such tests, especially when such tests are able to provide value in both the preclinical and the clinical settings.

Irritable bowel syndrome: Pathogenesis, diagnosis, treatment, and evidence-based medicine

Irritable bowel syndrome (IBS) is a chronic and debilitating functional gastrointestinal disorder that affects 9%-23% of the population across the world. The percentage of patients seeking health care related to IBS approaches 12% in primary care practices and is by far the largest subgroup seen in gastroenterology clinics. It has been well documented that these patients exhibit a poorer quality of life and utilize the health care system to a greater degree than patients without this diagnosis. The pathophysiology of IBS is not clear. Many theories have been put forward, but the exact cause of IBS is still uncertain. According to the updated ROME III criteria, IBS is a clinical diagnosis and presents as one of the three predominant subtypes: (1) IBS with constipation (IBS-C); (2) IBS with diarrhea (IBS-D); and (3) mixed IBS (IBS-M); former ROME definitions refer to IBS-M as alternating IBS (IBS-A). Across the IBS subtypes, the presentation of symptoms may vary among patients and change over time. Patients report the most distressing symptoms to be abdominal pain, straining, myalgias, urgency, bloating and feelings of serious illness. The complexity and diversity of IBS presentation makes treatment difficult. Although there are reviews and guidelines for treating IBS, they focus on the efficacy of medications for IBS symptoms using high-priority endpoints, leaving those of lower priority largely unreported. Therefore, the aim of this review is to provide a comprehensive evidence-based review of the diagnosis, pathogenesis and treatment to guide clinicians diagnosing and treating their patients.

Irritable bowel syndrome: a review and update

The understanding of irritable bowel syndrome (IBS) has undergone a rapid evolution with scientific advancement. IBS is a common functional bowel disorder that generates a significant health care burden and is the most commonly diagnosed gastrointestinal condition. There are well-established diagnostic criteria and algorithms for the initial evaluation of patients presenting with the symptoms of IBS. The symptoms can be targeted for therapy with a variety of pharmaceutical and nonpharmaceutical agents. Therapy should be individualized for the patient, and the cornerstone for any effective treatment strategy should be the solid patient-physician relationship.

Effects of Hypericum perforatum extract on rat irritable bowel syndrome

CONTEXT

In irritable bowel syndrome (IBS), disturbance of bowel motility is associated with infiltration of inflammatory mediators and cytokines into the intestine, such as neutrophils, myeloperoxidase (MPO), tumor necrosis factor alfa (TNF-α), and lipid peroxide.

AIMS

Regarding promising anti-inflammatory and anti-oxidative effects of Hypericum perforatum (HP) extract, besides its anti-depressant effect, this study was designed to evaluate the effects of HP in an experimental model of IBS.

SETTINGS AND DESIGN

IBS was induced by a 5-day restraint stress in rats. The HP extract was administered by gavage in doses of 150, 300, and 450 mg/kg for 26 days. Fluoxetine and loperamide were used as positive controls. Gastric emptying and small bowel and colon transit, besides the levels of TNF-α, MPO, lipid peroxidation, and antioxidant power, were determined in colon homogenates.

STATISTICAL ANALYSIS USED

Data were analyzed by one-way ANOVA followed by Tukey's post hoc test for multiple comparisons.

RESULTS

A significant reduction in small bowel and colonic transit (450 mg/kg), TNF-α, MPO, and lipid peroxidation and an increase in antioxidant power in all HP-treated groups (150, 300, and 450 mg/kg) were seen as compared with the control group. Gastric emptying did not alter significantly when compared with the control group. Treatment with loperamide (10 mg/kg) significantly inhibited gastric emptying and small bowel and colonic transit, while flouxetine (10 mg/kg) decreased gastric emptying, TNF-α, MPO, and lipid peroxidation and increased the antioxidant power of the samples in comparison with the control group.

CONCLUSIONS

HP diminished the recruitment of inflammatory cells and TNF-α following restraint stress not in a dose-dependent manner, possibly via inhibition of MPO activity and increasing colon antioxidant power, without any difference with fluoxetine. The HP extract inhibits small bowel and colonic transit acceleration like loperamide but has minimal effect on gastric emptying.

Methods for the assessment of small-bowel and colonic transit

Transit assessment of the small intestine and colon is relevant in the study of physiology, pathophysiology, and pharmacodynamics, and there is increasing use of small-bowel and colonic transit measurements in clinical practice as well. The main methods that are applied in clinical practice are substrate-hydrogen breath tests for small-bowel transit and radiopaque markers for colonic transit. Over the past 2-3 decades, scintigraphy has become the preferred standard in research studies, particularly for studies of pathophysiology and pharmacodynamics. New approaches include experimental stable isotope measurement of orocecal transit and the recently approved method using a wireless motility capsule that is validated as an accurate measurement of small-bowel and colonic transit.

Psychopharmacological treatment and psychological interventions in irritable bowel syndrome

Irritable bowel syndrome (IBS) accounts for 25% of gastroenterology output practice, making it one of the most common disorders in this practice. Psychological and social factors may affect the development of this chronic disorder. Furthermore, psychiatric symptoms and psychiatric diseases are highly prevalent in this condition, but the approach to treating these is not always straightforward. As emphasized in the biopsychosocial model of IBS, with regard to the modulatory role of stress-related brain-gut interactions and association of the disease with psychological factors and emotional state, it proves useful to encourage psychopharmacological treatments and psychosocial therapies, both aiming at reducing stress perception. The aim of this paper is to analyze the effectiveness of psychopharmacological treatment and psychological interventions on irritable bowel syndrome.

Bulking agents, antispasmodics and antidepressants for the treatment of irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder. The role of pharmacotherapy for IBS is limited and focused mainly on symptom control.

OBJECTIVES

The objective of this systematic review was to evaluate the efficacy of bulking agents, antispasmodics and antidepressants for the treatment of irritable bowel syndrome.

SEARCH STRATEGY

Computer assisted structured searches of MEDLINE, EMBASE, The Cochrane library, CINAHL and PsychInfo were conducted for the years 1966-2009. An updated search in April 2011 identified 10 studies which will be considered for inclusion in a future update of this review.

SELECTION CRITERIA

Randomized controlled trials comparing bulking agents, antispasmodics or antidepressants with a placebo treatment in patients with irritable bowel syndrome aged over 12 years were considered for inclusion. Only studies published as full papers were included. Studies were not excluded on the basis of language. The primary outcome had to include improvement of abdominal pain, global assessment or symptom score.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from the selected studies. Risk Ratios (RR) and Standardized Mean Differences (SMD) with 95% confidence intervals (CI) were calculated. A proof of practice analysis was conducted including sub-group analyses for different types of  bulking agents, spasmolytic agents or antidepressant medication. This was followed by a proof of principle analysis where only the studies with adequate allocation concealment were included.

MAIN RESULTS

A total of 56 studies (3725 patients) were included in this review. These included 12 studies of bulking agents (621 patients), 29 of antispasmodics (2333 patients), and 15 of antidepressants (922 patients). The risk of bias was low for most items. However, selection bias is unclear for many of the included studies because the methods used for randomization and allocation concealment were not described. No beneficial effect for bulking agents over placebo was found for improvement of abdominal pain (4 studies; 186 patients; SMD 0.03; 95% CI -0.34 to 0.40; P = 0.87), global assessment (11 studies; 565 patients; RR 1.10; 95% CI 0.91 to 1.33; P = 0.32) or symptom score (3 studies; 126 patients SMD -0.00; 95% CI -0.43 to 0.43; P = 1.00). Subgroup analyses for insoluble and soluble fibres also showed no statistically significant benefit. Separate analysis of the studies with adequate concealment of allocation did not change these results. There was a beneficial effect for antispasmodics over placebo for improvement of abdominal pain (58% of antispasmodic patients improved compared to 46% of placebo; 13 studies; 1392 patients; RR 1.32; 95% CI 1.12 to 1.55; P < 0.001; NNT = 7), global assessment (57% of antispasmodic patients improved compared to 39% of placebo; 22 studies; 1983 patients; RR 1.49; 95% CI 1.25 to 1.77; P < 0.0001; NNT = 5) and symptom score (37% of antispasmodic patients improved compared to 22% of placebo; 4 studies; 586 patients; RR 1.86; 95% CI 1.26 to 2.76; P < 0.01; NNT = 3). Subgroup analyses for different types of antispasmodics found statistically significant benefits for cimteropium/ dicyclomine, peppermint oil, pinaverium and trimebutine. Separate analysis of the studies with adequate allocation concealment found a significant benefit for improvement of abdominal pain. There was a beneficial effect for antidepressants over placebo for improvement of abdominal pain (54% of antidepressants patients improved compared to 37% of placebo; 8 studies; 517 patients; RR 1.49; 95% CI 1.05 to 2.12; P = 0.03; NNT = 5), global assessment (59% of antidepressants patients improved compared to 39% of placebo; 11 studies; 750 patients; RR 1.57; 95% CI 1.23 to 2.00; P < 0.001; NNT = 4) and symptom score (53% of antidepressants patients improved compared to 26% of placebo; 3 studies; 159 patients; RR 1.99; 95% CI 1.32 to 2.99; P = 0.001; NNT = 4). Subgroup analyses showed a statistically significant benefit for selective serotonin releasing inhibitors (SSRIs) for improvement of  global assessment and for tricyclic antidepressants (TCAs) for improvement of abdominal pain and symptom score. Separate analysis of studies with adequate allocation concealment found a significant benefit for improvement of symptom score and global assessment. Adverse events were not assessed as an outcome in this review.

AUTHORS' CONCLUSIONS

There is no evidence that bulking agents are effective for treating IBS.  There is evidence that antispasmodics are effective for the treatment of IBS. The individual subgroups which are effective include: cimetropium/dicyclomine, peppermint oil, pinaverium and trimebutine. There is good evidence that antidepressants are effective for the treatment of IBS. The subgroup analyses for SSRIs and TCAs are unequivocal and their effectiveness may depend on the individual patient. Future research should use rigorous methodology and valid outcome measures.

Effects of Hypericum perforatum extract on rat irritable bowel syndrome

CONTEXT

In irritable bowel syndrome (IBS), disturbance of bowel motility is associated with infiltration of inflammatory mediators and cytokines into the intestine, such as neutrophils, myeloperoxidase (MPO), tumor necrosis factor alfa (TNF-α), and lipid peroxide.

AIMS

Regarding promising anti-inflammatory and anti-oxidative effects of Hypericum perforatum (HP) extract, besides its anti-depressant effect, this study was designed to evaluate the effects of HP in an experimental model of IBS.

SETTINGS AND DESIGN

IBS was induced by a 5-day restraint stress in rats. The HP extract was administered by gavage in doses of 150, 300, and 450 mg/kg for 26 days. Fluoxetine and loperamide were used as positive controls. Gastric emptying and small bowel and colon transit, besides the levels of TNF-α, MPO, lipid peroxidation, and antioxidant power, were determined in colon homogenates.

STATISTICAL ANALYSIS USED

Data were analyzed by one-way ANOVA followed by Tukey's post hoc test for multiple comparisons.

RESULTS

A significant reduction in small bowel and colonic transit (450 mg/kg), TNF-α, MPO, and lipid peroxidation and an increase in antioxidant power in all HP-treated groups (150, 300, and 450 mg/kg) were seen as compared with the control group. Gastric emptying did not alter significantly when compared with the control group. Treatment with loperamide (10 mg/kg) significantly inhibited gastric emptying and small bowel and colonic transit, while flouxetine (10 mg/kg) decreased gastric emptying, TNF-α, MPO, and lipid peroxidation and increased the antioxidant power of the samples in comparison with the control group.

CONCLUSIONS

HP diminished the recruitment of inflammatory cells and TNF-α following restraint stress not in a dose-dependent manner, possibly via inhibition of MPO activity and increasing colon antioxidant power, without any difference with fluoxetine. The HP extract inhibits small bowel and colonic transit acceleration like loperamide but has minimal effect on gastric emptying.

Evolution of clinical trials for irritable bowel syndrome: issues in end points and study design

Irritable bowel syndrome (IBS) involves a broad range of physiological and psychological alterations that may affect brain-gut dysregulation, gut function, visceral perception, and mucosal integrity and function. Despite advances in our understanding of basic neuroenteric mechanisms and the role of effectors and transmitters in the brain-gut axis, a reliable biologic marker of IBS has yet to be identified. IBS diagnosis and status depend entirely on an assessment of IBS signs and symptoms. This has made development of optimal end points and study design for evaluation of efficacy of IBS drugs a challenge. This article addresses three main topics: the evolution of primary end points for IBS clinical trials; a potential path forward for IBS end points in new clinical trials; and recommendations for the future development of patient-reported outcome (PRO) instruments for use in IBS clinical trials.

Postprandial changes in small bowel water content in healthy subjects and patients with irritable bowel syndrome

BACKGROUND & AIMS

Postprandial symptoms are common in patients with irritable bowel syndrome with diarrhea (IBS-D) and could be diet related. We studied postprandial changes in distribution of water in the upper gastrointestinal tract of healthy volunteers (HVs) and patients with IBS-D after contrasting meals.

METHODS

In study 1, 11 HVs consumed 350-mL test meals with 5% mannitol (unabsorbable) or 5% glucose (readily absorbed). In study 2, 17 HVs consumed a 331-kcal meal, with or without 15 g bran. In study 3, 26 patients with IBS-D consumed the study 2 diet with bran meal. All subjects underwent serial magnetic resonance imaging analysis.

RESULTS

In study 1, subjects' small bowel water content (SBWC) increased after the mannitol but not glucose meals, reaching 381 mL (interquartile range, 343-491 mL) and 47 mL (18-78 mL), respectively, 40 minutes after eating (P < .001). In study 2, SBWC initially decreased after both meal types and then increased, plateauing at 180-405 minutes and was greater after the bran meal (P = .02). In study 3, fasting and postprandial SBWC was lower in IBS-D than in HVs (P < .05 and P < .0001, respectively). Patients with IBS-D had faster orocecal transit times (135 minutes; 90-180 minutes) compared with HVs (225 minutes; 203-293 minutes; P < .0001) and reduced terminal ileum diameter (P < .003).

CONCLUSIONS

Postprandial SBWC initially decreases, because of rapid, nutrient-driven fluid absorption, and then increases after a mixed liquid/solid meal. Patients with IBS-D have reduced fasting and postprandial SBWC with faster transit, possibly indicating increased small intestinal tone.

Serotoninergic and non-serotoninergic effects of two tricyclic antidepressants on visceral nociception in a rat model

OBJECTIVE

Tricyclic antidepressants (TCAs) are well established in the treatment of patients with irritable bowel syndrome (IBS). The effects are believed to be linked to serotoninergic antinociceptive properties, but data on the antinociceptive effects of various TCAs with variable serotoninergic and non-serotoninergic properties have not been investigated. The aim of this study was to compare the antinociceptive effects of different TCAs.

MATERIAL AND METHODS

Colorectal distension (CRD) using a barostat device was carried out in rats and the visceromotor response (VMR) to CRD was quantified by abdominal wall electromyography. Prior to CRD, saline (control), amitriptyline (AM), desipramine (DES), reserpine (RES) or a combination of TCAs and RES (AM + RES or DES + RES) was applied intraperitoneally. Serum 5-HT levels were determined using high-performance liquid chromatography (HPLC). RES was used to antagonize the serotoninergic actions of TCAs in order to discriminate between these effects and others.

RESULTS

Both TCAs decreased the VMR compared to placebo. After RES application without TCAs, the VMR was increased compared to controls (6403 microV+/-1772 microV). Co-administration of AM and RES resulted in a modest decrease in VMR (5774 microV+/-1953 microV), while in rats treated with RES and DES the VMR again was significantly lower (3446 microV (+/-1347 microV; p <0.05)). 5-HT levels were higher in TCA pretreated rats than those in controls and significantly lower 5-HT levels were found in all rats pretreated with RES.

CONCLUSIONS

AM and DES have antinociceptive properties while RES is pro-nociceptive. The antinociceptive effects of DES are not abolished by RES pretreatment, while AM only attenuates the pro-nociceptive effects of RES. The non-serotoninergic properties of TCAs substantially contribute to the differences in the antinococeptive effects of various TCAs.

A randomized controlled trial of imipramine in patients with irritable bowel syndrome

AIM: To study the efficacy of low-dose imipramine in relieving symptoms associated with the irritable bowel syndrome (IBS).

METHODS: A randomized, double-blind trial of 25 mg imipramine vs matched placebo for 12 wk was performed. Doubling the dose was allowed once at week 2 in case of an unsatisfactory early response. Primary efficacy variables were subjective global symptom relief and quality of life (QoL) using SF-36 at week 12.

RESULTS: One hundred and seven patients were enrolled by advertisement or referral by general practitioners and 56 (31 imipramine: 25 placebo) completed the 16-wk study. Baseline characteristics were comparable. A high overall dropout rate was noted in the imipramine and placebo arms (47.5% vs 47.9%, P > 0.05), a mean of 25.0 and 37.4 d from enrollment, respectively (P < 0.05). At the end of 12 wk, there was a significant difference in global symptom relief with imipramine over placebo (per-protocol: 80.6% vs 48.0%, P = 0.01) and a trend on intent-to-treat (ITT) analysis (42.4% vs 25.0%, P = 0.06). This improvement was evident early and persisted to week 16 (P = 0.024 and 0.053 by per-protocol and ITT analyses, respectively). Mean cumulative and component-specific SF-36 scores improved in the imipramine group only (per-protocol, P < 0.01). Drug-related adverse events leading to patient dropout were more common in the imipramine group (25.4% vs 12.5%, P > 0.05).

CONCLUSION: Imipramine may be effective in the treatment of IBS patients and is associated with improved QoL. Careful patient selection, initiation of a low dose with gradual escalation and monitoring for side effects may result in an improved therapeutic response.

Challenges to the therapeutic pipeline for irritable bowel syndrome: end points and regulatory hurdles

Recent advances in our understanding of basic neuroenteric mechanisms and the role of effectors and transmitters in the brain-gut axis have provided opportunities to develop new therapeutic agents for irritable bowel syndrome (IBS). Furthermore, human pharmacodynamic studies utilizing transit, colonic, or rectal sensitivity and brain imaging have been useful in determining therapeutic efficacy (particularly for drugs that act on motor function). This review provides an overview of medications that have not yet been approved for treatment of patients with IBS yet have shown promise in phase IIB trials. These include drugs that act on the serotonin receptor and transporter system: antidepressants, norepinephrine reuptake inhibitors, opioids, cholecystokinin antagonists, neurokinin-antagonists, chloride channel activators, guanylate cyclase C agonists, atypical benzodiazepines, probiotics, and antibiotics. The changing landscape in the regulatory approval process has impacted the development of IBS drugs. Guidance documents from regulatory agencies in Europe and the United States have focused on patients' reported outcomes and associated quality of life. After a decade of experience with different end points that have generated some data on psychometric validation and unprecedented information about responsiveness of the binary or global end points to drug therapy, it is necessary to pursue further validation studies before or during pivotal phase IIB or III trials. The hope of providing relief to patients should galvanize all parties to achieve these goals.

The effect of short-term, low-dose tricyclic and tetracyclic antidepressant treatment on satiation, postnutrient load gastrointestinal symptoms and gastric emptying: a double-blind, randomized, placebo-controlled trial

Antidepressants are commonly prescribed for patients with functional dyspepsia. However, the effect of tricyclic antidepressants on satiation and gastric emptying remains unclear, and there are no data for tetracyclic compounds. To compare the effects of nortriptyline (maximum dose: 50 mg daily) and mirtazapine (30 mg daily) vs placebo on gastric emptying, gastric satiation and postprandial symptoms after a nutrient load in healthy volunteers. Randomized, double-blind, placebo-controlled study evaluated gastric function before and after 14 days of nortriptyline (n = 13), mirtazapine (n = 13), or placebo (n = 14) in healthy volunteers. Validated methods were used to study gastric emptying ((13)C-octanoate) and satiation postnutrient drink test. The three arms were comparable with regard to age, gender, body mass index and hospital anxiety/depression scale. There were no statistically significant effects of mirtazapine or nortriptyline on gastric emptying compared to placebo (P = 0.34). Maximum tolerated volume was similar on drug and placebo (P = 0.56). Aggregate symptom score 30 min postmaximum tolerated volume after nutrient drink challenge on placebo was 132 (+/-21), vs 165 (+/-21) on mirtazapine, and 126 (+/-21) on nortriptyline 50 mg respectively (P = 0.28). Tricyclic and tetracyclic antidepressant agents do not appear to have significant effects on gastric motor or satiation postnutrient challenge in healthy individuals at the doses tested.

Intestinal permeability and irritable bowel syndrome

Based on a systematic PubMed search, this short review addresses why intestinal permeability may be important in the pathobiology of irritable bowel syndrome (IBS), the evidence of abnormal permeability in patients with IBS, and the pros and cons of the different probe molecules available to assess intestinal permeability. While a subgroup of patients with IBS appears to have evidence of increased intestinal permeability, improvements in the methods and validation are key to further research in this field in order to better understand intestinal barrier functions in IBS.

Enterochromaffin cells of the human gut: sensors for spices and odorants

BACKGROUND & AIMS

Release of serotonin from mucosal enterochromaffin cells triggered by luminal substances is the key event in the regulation of gut motility and secretion. We were interested to know whether nasal olfactory receptors are also expressed in the human gut mucosa by enterochromaffin cells and whether their ligands and odorants present in spices, fragrances, detergents, and cosmetics cause serotonin release.

METHODS

Receptor expression was studied by the reverse-transcription polymerase chain reaction method in human mucosal enterochromaffin cells isolated by laser microdissection and in a cell line derived from human enterochromaffin cells. Activation of the cells by odorants was investigated by digital fluorescence imaging using the fluorescent Ca(2+) indicator Fluo-4. Serotonin release was measured in culture supernatants by a serotonin enzyme immunoassay and amperometry using carbon fiber microelectrodes placed on single cells.

RESULTS

We found expression of 4 olfactory receptors in microdissected human mucosal enterochromaffin cells and in a cell line derived from human enterochromaffin cells. Ca(2+) imaging studies revealed that odorant ligands of the identified olfactory receptors cause Ca(2+) influx, elevation of intracellular free Ca(2+) levels, and, consequently, serotonin release.

CONCLUSIONS

Our results show that odorants present in the luminal environment of the gut may stimulate serotonin release via olfactory receptors present in human enterochromaffin cells. Serotonin controls both gut motility and secretion and is implicated in pathologic conditions such as vomiting, diarrhea, and irritable bowel syndrome. Thus, olfactory receptors are potential novel targets for the treatment of gastrointestinal diseases and motility disorders.

Cultural adaptation and application of the IBS-QOL in China: a disease-specific quality-of-life questionnaire

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic and episodic illness characterized by altered bowel habits and associated abdominal pain. At present, IBS is one of the most common functional gastrointestinal and motility disorders affecting countries around the world. Surveys have found that patients with IBS have a significantly lower health-related quality of life.

OBJECTIVES

The aim of this study was to translate and examine the validity of the Irritable Bowel Syndrome-Quality of Life questionnaire (IBS-QOL) in patients suffering from IBS in China.

METHODS

A structured procedure was used for the translation and cultural adaptation of the original English IBS-QOL into Chinese. The questionnaire was administered to 73 clinical patients with IBS and 70 healthy individuals. Psychometric testing for reliability, validity and responsiveness followed standardized procedures. Test-retest reliability (10-20 hours) was assessed using the clinical patients. Follow-up (4 weeks) was collected for 61 clinical patients. All enrolled patients also completed the Short Form-36 Health Survey (SF-36) at the baseline visit. Responsiveness to treatment (Venlafaxine and traditional Chinese herbal medicine) was assessed by one-way ANOVA methods.

RESULTS

The average length of time required to complete the questionnaire was short (5.63 min for IBS patients and 5.54 min for healthy subjects by self-administration). Internal consistency (Cronbach's alpha) values ranged from 0.722 to 0.914 for the Chinese IBS-QOL subscales and test-retest reliability coefficients were higher than 0.920 on all subscales. The convergent and discriminate validity results comparing the Chinese translation of the IBS-QOL overall score and the SF-36 subscales confirmed our predicted hypotheses. The Chinese IBS-QOL scores are more highly correlated with social functioning, vitality and general health (SF-36) and show weaker associations with physical functioning, role physical, mental health, and bodily pain (SF-36). The Chinese translation of the IBS-QOL was responsive to treatment.

CONCLUSION

In general, the Chinese translation of the IBS-QOL, after cultural adaptation and revision, possesses good reliability, validity and responsiveness. It is a reliable and valid instrument to assess the quality of life in Chinese patients suffering from IBS and is an appropriate measure to use in further clinical trials or for related research projects in China.

Tricyclic antidepressants for chronic vomiting in diabetic patients

Chronic vomiting in diabetic patients often is unresponsive to prokinetic agents and poorly explained by delayed gastric emptying or neuropathy. This retrospective study examines clinical response to tricyclic antidepressants, a treatment of reported benefit in nondiabetic patients with unexplained vomiting syndromes. Outcomes were studied in 24 diabetic outpatients who had been treated with tricyclic antidepressants specifically for nausea and vomiting after an unsatisfactory response to prokinetic therapy. Symptom patterns and treatment response were determined from chart review and telephone interview. Ten patients (42%) had recurrent, stereotypical vomiting episodes with symptom-free intervals suggesting cyclic vomiting syndrome; 14 (58%) had persistent symptoms. By chart review, at least moderate symptom response to tricyclic antidepressant treatment (median dosage, 50 mg/day) occurred in 88% of subjects, with complete or nearly complete resolution of symptoms in one-third. At follow-up interview, 77% self-reported at least moderate symptom improvement during therapy and 68% rated tricyclic antidepressants the most effective treatment received. Duration of diabetes, presence of neuropathy, and psychiatric status were not predictive of treatment outcome in multivariate analysis, but a cyclical symptom pattern attenuated antidepressant response (P< 0.05). In this retrospective review, the majority of diabetic patients with chronic vomiting and incomplete response to prokinetic therapy benefited from tricyclic antidepressants in low-dose, open-label regimens and rated them the most effective treatment received. This therapeutic option should be further studied in diabetic patients considering the morbidity of chronic vomiting in this population.

Symptomatic overlap between irritable bowel syndrome and microscopic colitis

BACKGROUND

Microscopic colitis is diagnosed on the basis of histologic criteria, and irritable bowel syndrome (IBS) is diagnosed by symptom-based criteria. There has been little investigation into the symptomatic overlap between these conditions. Our aim was to assess the prevalence of symptoms of irritable bowel syndrome in a population-based cohort of patients with microscopic colitis.

METHODS

The Rochester Epidemiology Project (REP), a medical records linkage system providing all health care data for the defined population of Olmsted County, Minnesota, was used to identify all county residents with a diagnosis of microscopic colitis between 1985 and 2001. The medical records of these individuals were reviewed to ascertain symptoms consistent with Rome, Rome II, and Manning criteria for irritable bowel syndrome.

RESULTS

One hundred thirty-one cases of microscopic colitis were identified. Median age at diagnosis was 68 years (range, 24-95); 71% were women. Sixty-nine (53%) and 73 (56%) met Rome and Rome II criteria for irritable bowel syndrome, respectively. Fifty-four (41%) had three or more Manning criteria. Forty-three (33%) had previously been diagnosed with irritable bowel syndrome.

CONCLUSIONS

In this population-based cohort of histologically confirmed microscopic colitis, approximately one-half met symptom-based criteria for the diagnosis of irritable bowel syndrome. The clinical symptom-based criteria for irritable bowel syndrome are not specific enough to rule out the diagnosis of microscopic colitis. Therefore, patients with suspected diarrhea-predominant irritable bowel syndrome should undergo biopsies of the colon to investigate for possible microscopic colitis if symptoms are not well controlled by antidiarrheal therapy.

The patient with refractory diarrhoea

Persistent diarrhoea continues to present a management challenge to clinicians around the world. The investigation of persistent diarrhoea requires a logical hierarchical approach to ensure that resources are used appropriately and patients are not put at unnecessary risks during the investigative process. A 5-step process is described in which functional diarrhoea is excluded early in the workup, which might include a measurement of 24h faecal weight. Once infection, drugs and laxatives have been excluded more invasive tests such as endoscopy are sequentially introduced to exclude inflammatory disease and small bowel and pancreatic malabsorption. When the common causes have been excluded there remains a group of patients with high volume watery diarrhoea due to a variety of causes include the neuroendocrine diarrhoeas. A case of fictitious diarrhoea is described which illustrates the value of complete fluid balance studies, faecal osmolality and other biochemical faecal analyses. The management of some selected causes of refractory diarrhoea is discussed including functional diarrhoea, diabetic diarrhoea, diarrhoea dues to protozoal infections, microscopic colitis and antibiotic associated diarrhoea.

Imipramine inhibits A-type delayed rectifier and ATP-sensitive K+ currents independent of G-protein and protein kinase C in murine proximal colonic myocytes

The effects of imipramine on A-type delayed rectifier K+ currents and ATP-sensitive K+ (KATP) currents were studied in isolated murine proximal colonic myocytes using the whole-cell patch-clamp technique. Depolarizing test pulses between -80 mV and +30 mV with 10 mV increments from the holding potential of -80 mV activated voltage-dependent outward K+ currents that peaked within 50 ms followed by slow decreasing sustained currents. Early peak currents were inhibited by the application of 4-aminopyridine, whereas sustained currents were inhibited by the application of TEA. The peak amplitude of A-type delayed rectifier K+ currents was reduced by external application of imipramine. The half-inactivation potential and the half-recovery time of A-type delayed rectifier K+ currents were not changed by imipramine. With 0.1 mM ATP and 140 mM K+ in the pipette and 90 mM K+ in the bath solution and a holding potential of -80 mV, pinacidil activated inward currents; this effect was blocked by glibenclamide. Imipramine also inhibited KATP currents. The inhibitory effects of imipramine in A-type delayed rectifier K+ currents and KATP currents were not changed by guanosine 5-O-(2-thiodiphosphate) (GDPbetaS) and chelerythrine, a protein kinase C inhibitor. These results suggest that imipramine inhibits A-type delayed rectifier K+ currents and KATP currents in a manner independent of G-protein and protein kinase C.

Review article: modulation of the brain-gut axis as a therapeutic approach in gastrointestinal disease

BACKGROUND

The importance of bi-directional brain-gut interactions in gastrointestinal illness is increasingly being recognized, most prominently in the area of functional gastrointestinal disorders. Numerous current and emerging therapies aimed at normalizing brain-gut interactions are a focus of interest, particularly for irritable bowel syndrome and functional dyspepsia.

METHODS

A literature search was completed for preclinical and clinical studies related to central modulation of gastrointestinal functions and published in English between 1980 and 2006.

RESULTS

Existing data, while sparse, support the use of different classes of antidepressant drugs, including tricyclics, and selective and non-selective serotonin reuptake inhibitors in irritable bowel syndrome. Serotonin receptor agonists and antagonists with peripheral and possibly central effects are effective in treating specific subtypes of irritable bowel syndrome. Based largely on theoretical and preclinical evidence, several novel compounds that selectively target receptors at multiple levels within the brain-gut axis such as neurokinin, somatostatin and corticotropin-releasing factor receptor antagonists are promising.

CONCLUSIONS

This review discusses the rationale for modulation of the brain-gut axis in the treatment of functional gastrointestinal disorders and highlights the most promising current and future therapeutic strategies.

Managing nonmalignant chronic abdominal pain and malignant bowel obstruction

Evaluation of abdominal pain requires an understanding of the possible causes(benign or malignant) and recognition of typical patterns and clinical presentation. Abdominal pain has multiple causes; associated signs and symptoms may aid in the diagnosis. Remember that some patients will not have a textbook presentation, and unusual causes for pain must be considered. Those with chronic pancreatitis with structural complications should be operated on early, whereas those with other types of chronic pancreatitis should receive medical therapy focusing on alleviating symptoms. Control of the most troublesome symptoms will provide the best management for IBS. Pharmacologic success in bowel obstruction depends on the level and degree of obstruction. Decision making is based on reasonable expectations of survival, treatment-related success, performance status, and goals of care. Quality of life will be enhanced by appropriate symptom management.

Functional diarrhea

Functional diarrhea occurs as part of the irritable bowel syndrome (IBS) and as an isolated symptom as functional (painless) diarrhea. Progress has been made in defining these disorders and in identifying new mechanisms involved in symptom production. A strong link exists between intestinal infection and IBS, as is the role of 5-hydroxytryptamine (5-HT). The importance of persistent subclinical inflammation is also emerging as a potential etiologic factor, particularly in post-infectious IBS. Although changes in the bacterial flora and bacterial overgrowth have been put forward as additional new contributors to symptom production, the case is not strong. These developments in pathogenesis have facilitated the introduction of new therapies. 5-HT(3) antagonists reduce bowel frequency and pain in women with diarrhea-predominant IBS, but their use is limited because of ischemic colitis. Prednisolone lacks efficacy, and early results with probiotics and herbal remedies are encouraging but require confirmation by larger trials.

Drugs affecting visceral sensitivity: ready for the prime time?

Visceral sensitivity has been recognized over the last decade as a frequent pathophysiological component of functional bowel disorders. Studies in animals and humans have identified numerous neurotransmitters involved in the processing of sensations from the gut to the brain. However, up to now none of them has actually been proven to have a marked clinical efficacy and the benefit comes rather from their action of bowel disturbances. Reproducible tests are lacking to detect visceral hypersensitivity in humans and distension tests are difficult to undertake in a clinical setting. Therefore, abnormal visceral sensitivity may not be regarded as a tool to select IBS patients as candidates for a given treatment.

Action of imipramine on activated ATP-sensitive K(+) channels in interstitial cells of Cajal from murine small intestine

Tricyclic antidepressants have been widely used for the treatment of depression and as a therapeutic agent for the altered gastrointestinal (GI) motility of irritable bowel syndrome (IBS). The aim of this study was to clarify whether antidepressants directly modulate pacemaker currents in cultured interstitial cells of Cajal (ICC). We used the whole-cell patch-clamp techniques at 30 degrees C in cultured ICC from the mouse small intestine. Treatment of pinacidil, an ATP-sensitive K(+) channel opener, in the ICC using the current clamping mode, produced hyperpolarization of the membrane potential and decreased the amplitude of the pacemaker potentials. With the voltage clamp mode, we observed a decrease in the frequency and amplitude of pacemaker currents and increases in the resting outward currents. These effects of pinacidil on pacemaker potentials and currents were completely suppressed by glibenclamide, an ATP-sensitive K(+) channel blocker. Also, with the current clamp mode, imipramine blocked the affect of pinacidil on the pacemaker potentials. Observations of the voltage clamp mode with imipramine, desipramine and amitryptyline suppressed the action of pinacidil in the ICC. Next, we examined whether protein kinase C (PKC) and the G protein are involved in the action of imipramine on pinacidil induced pacemaker current inhibition. We used chelerythrine, a potent PKC inhibitor and GDPbetaS, a nonhydrolyzable guanosine 5-diphosphate (GDP) analogue that permanently inactivates GTP-binding proteins. We found that pretreatment with chelerythrine and intracellular application of GDPbetaS had no influence on the blocking action of imipramine on inhibited pacemaker currents by pinacidil. We conclude that imipramine inhibited the activated ATP-sensitive K(+) channels in ICC. This action does not appear to be mediated through the G protein and protein kinase C. Furthermore, this study may suggest another possible mechanism for tricyclic antidepressants related modulation of GI motility.

Nerves, reflexes, and the enteric nervous system: pathogenesis of the irritable bowel syndrome

The bowel exhibits reflexes in the absence of CNS input. To do so, epithelial sensory transducers, such as enterochromaffin (EC) cells, activate the mucosal processes of intrinsic (IPANs) and extrinsic primary afferent (sensory) neurons. EC cells secrete serotonin (5-HT) in response to mucosal stimuli. Submucosal IPANs, which secrete acetylcholine and calcitonin gene-related peptide, initiate peristaltic and secretory reflexes and are activated via "5-HT1P" receptors. Release of neurotransmitters is enhanced by 5-HT4 receptors, which are presynaptic and strengthen neurotransmission in prokinetic pathways. 5-HT3 receptors mediate signaling to the CNS and thus ameliorate cancer chemotherapy-associated nausea and the visceral hypersensitivity of diarrhea-predominant irritable bowel syndrome (IBS-D); however, because 5-HT3 receptors also mediate fast ENS neurotransmission and activate myenteric IPANs, they may be constipating. 5-HT4 agonists are prokinetic and relieve discomfort and constipation in IBS-C and chronic constipation. 5-HT4 agonists do not initiate peristaltic and secretory reflexes but strengthen pathways that are naturally activated. Serotonergic signaling in the mucosa and the ENS is terminated by a transmembrane 5-HT transporter, SERT. Mucosal SERT and tryptophan hydroxylase-1 expression are decreased in experimental inflammation, IBS-C, IBS-D, and ulcerative colitis. Potentiation of 5-HT due to the SERT decrease could account for the discomfort and diarrhea of IBS-D, while receptor desensitization may cause constipation. Similar symptoms are seen in transgenic mice that lack SERT. The loss of mucosal SERT may thus contribute to IBS pathogenesis.