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

Factors That Predict Magnitude, Timing, and Persistence of Placebo-Like Response in Patients With Irritable Bowel Syndrome

BACKGROUND AND AIMS

Placebo response impedes the development of novel irritable bowel syndrome (IBS) therapies and the interpretability of randomized clinical trials. This study sought to characterize the magnitude, timing, and durability of IBS symptom relief in patients undergoing a non-drug placebo-like control.

METHODS

One hundred forty-five Rome III-diagnosed patients (80% F, M age = 42 years) were assigned to education/nondirective support delivered over a 10-week acute phase. Treatment response was based on the IBS version of the Clinical Global Improvement Scale completed 2 weeks after treatment ended. Candidate predictors were assessed at baseline (eg, emotion regulation, pain catastrophizing, distress, neuroticism, stress, somatization, gastrointestinal-specific anxiety) or clinically relevant points during treatment (patient-provider relationship, treatment expectancy/credibility).

RESULTS

Midtreatment response was associated with lower levels of stress and somatization at baseline and greater patient-provider agreement on treatment tasks (P < .001). Treatment response was associated with baseline gastroenterologist-rated IBS severity, anxiety, ability to reappraise emotions to reduce their impact [cognitive reappraisal], and agreement that provider and patient shared goals from provider perspective (P < .001). The day-to-day ability to reappraise emotions at baseline distinguished rapid from delayed placebo responders (P = .011).

CONCLUSION

Patient beliefs (eg, perceived stress, cognitive reappraisal) impacted the magnitude, timing, and persistence of placebo response measured at midway point of acute phase and 2 weeks after treatment discontinuation. Baseline beliefs that patients could alter the impact of stressful events by rethinking their unpleasantness distinguished rapid vs delayed placebo responders. Collaborative agreement between doctor and patient around shared tasks/goals from the clinician perspective predicted placebo response.

Assessing the post-treatment therapeutic effect of tongxie in irritable bowel syndrome: a randomized controlled trial

Diarrhea predominant irritable bowel syndrome (IBS) is a highly relapsing gastrointestinal disorder decreasing the quality of life. Existing studies indicated that the therapeutic effects maintained for a period of time after the treatments were discontinued (post-treatment therapeutic effects or PTTE). In this study, we aim to assess the PTTE of tongxie. We performed a multiple center, controlled, double blind study of patients with IBS randomized to tongxie (n=120) or placebo (n=120) for 4 weeks and followed up for 57 weeks. The primary outcomes were abdominal pains and stool consistency. The secondary outcomes were pain frequency and stool frequency. Tertiary outcomes were adverse effects and global overall symptom. The outcome data were collected at days 1, 2, 3, weeks 1 and 4 during the treatment and at days 1, 2, 3, until week 57 during the post-treatment. Significantly more patients receiving tongxie were clinical responders to the primary and secondary endpoints from day 1 until the end of the treatment. The positive effects of tongxie were maintained until 17 to 25 weeks after tongxie was discontinued. The relapse-free probabilities in the tongxie group were significantly higher than those in the placebo group (P <.001). Twenty-five weeks after the therapies were discontinued could be considered as IBS natural history. During this period, an average of 53.8% - 56.3% of patients (pool tongxie and placebo data together) had IBS symptoms (pain scale ≥ 3, stool consistency ≥ 5). In particular, at the end of this study (week 61), 145 (54.2%) patients had IBS symptoms. Our results provide clinical insights into efficient and cost-effective management of refractory IBS, and lend support to the IBS management that the selection of a therapy should consider both its effectiveness during treatment and its PTTE after the treatment. Clinicaltrials.gov no: NCT02330029.

Nonfood Prebiotic, Probiotic, and Synbiotic Use Has Increased in US Adults and Children From 1999 to 2018

BACKGROUND & AIMS

Public interest in pre-, pro-, and synbiotic products is increasing because of interactions between gut microbiota and human health. Our aim was to describe nonfood (from dietary supplements or medication) pre-, pro-, and synbiotic use by US adults and children and reported reasons.

METHODS

Using data from the National Health and Nutrition Examination Survey (NHANES), we text-mined dietary supplement and prescription medication labels and ingredients to identify pre-, pro-, and synbiotic products used in the past 30 days. We describe trends in use from 1999 to 2018 (n = 101,199) and prevalence in 2015-2016 and 2017-2018 (n = 19,215) by age groups, sex, ethnicity/race, education, income, self-reported diet and health quality, and prescription gastrointestinal medication use stratified by children (<19 years) and adults (19+ years).

RESULTS

Nonfood pre-, pro-, and synbiotic use increased up to 3-fold in recent cycles. Prevalence of use for all ages for prebiotics was 2.4% (95% confidence interval [CI], 2.0-2.9), for probiotics was 4.5% (95% CI, 3.5-5.6), and for synbiotics was 1.1% (95% CI, 0.8-1.5). Use was highest among older adults (8.8% [95% CI, 5.4-13.3] among those aged 60-69 years for probiotics), non-Hispanic Whites, those with higher educational attainment and income, those with more favorable self-reported diet or health quality, and those with concurrent prescription gastrointestinal medication use. The top reasons for use were for digestive health and to promote/maintain general health. Less than 30% reported using these products based on a health care provider's recommendation.

CONCLUSIONS

One in 20 US adults or children use nonfood pre-, pro-, or synbiotic products, and use has sharply increased in recent years. Most individuals voluntarily take these products for general digestive or overall health reasons.

Abdominal Massage Reduces Visceral Hypersensitivity via Regulating GDNF and PI3K/AKT Signal Pathway in a Rat Model of Irritable Bowel Syndrome

Changes in gut motility and visceral hypersensitivity are two major features of irritable bowel syndrome (IBS). Current drug treatments are often poorly efficacious, with many side effects for patients with IBS. Complementary therapies, such as acupuncture or abdominal massage, have received more attention in recent years. In this study, a rat model of IBS with diarrhea (IBS-D) was established by instillation of acetic acid from the colon. The effects of abdominal massage on changes in gut motility, visceral hypersensitivity, and the possible mechanism were investigated. Continuous abdominal massage could decrease the stool consistency score and increase the efflux time of glass beads compared with model groups, while also decreasing mast cell counts in IBS-D rats. The mRNA and protein expressions of neuronal nitric oxide synthase (nNOS), choline acetyl transferase (CHAT), and protein gene product 9.5 (PGP9.5) were significantly upregulated by continuous abdominal massage compared with model groups. Continuous abdominal massage also improved the ultrastructure of enteric glial cells (EGCs) by decreasing the number of mitochondria and increasing the level of the heterochromatin. Meanwhile, continuous abdominal massage could upregulate the expression of glial cell line-derived neurotrophic factor (GDNF) and P-Akt/Akt. Furthermore, it could reduce visceral hypersensitivity and improve the IBS-D symptoms by regulating the phosphoinositide 3-kinase (PI3K)-Akt pathway, which would provide a novel method for the treatment of IBS-D in the clinical setting.

Efficacy of the Combination of Pinaverium Bromide 100 mg Plus Simethicone 300 mg in Abdominal Pain and Bloating in Irritable Bowel Syndrome: A Randomized, Placebo-controlled Trial

GOALS

We aimed to evaluate the efficacy and safety of PB+S (pinaverium bromide 100 mg plus simethicone 300 mg) in patients with irritable bowel syndrome (IBS).

BACKGROUND

IBS is a multifactorial disorder; thus, combination therapy with different mechanisms of action is expected to be useful. PB+S has shown effectiveness in an open-label clinical study in IBS. However, there are no placebo-controlled trials.

MATERIALS AND METHODS

IBS-Rome III patients with abdominal pain/discomfort for at least 2 days within the week prior to baseline assessment were included in this 12-week, randomized, double-blind, placebo-controlled study of PB+S versus placebo, bid. The primary endpoint was overall symptom improvement, evaluated weekly by the patient (Likert Scale). Secondary endpoints included the weekly improvement in the severity of abdominal pain and bloating assessed both by patients (10-cm Visual Analogue Scale) and investigators (Likert Scale); frequency of Bristol Scale stool types (consistency) evaluated by patients and the IBS Quality of Life scores.

RESULTS

A total of 285 patients (female: 83%; 36.5±8.9 y old) received at least 1 dose of PB+S (n=140) or placebo (n=145). No difference was observed in overall symptom improvement between the groups (P=0.13). However, PB+S was superior in abdominal pain (effect size: 31%, P=0.038) and bloating (33%, P=0.019). Patients with IBS-C and IBS-M showed the best improvement in the frequency of stool types with PB+S. No differences were observed in IBS Quality of Life scores and adverse events.

CONCLUSIONS

PB+S was superior to placebo in improving abdominal pain and bloating in patients with active IBS. The effect on the frequency of stool consistency was particularly significant in IBS-C and IBS-M.

Defining Optimal Care for Functional Gut Disorders - Multi-Disciplinary Versus Standard Care: A Randomized Controlled Trial Protocol

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are the commonest reason for gastroenterological consultation, with patients usually seen by a specialist working in isolation. There is a wealth of evidence testifying to the benefit provided by dieticians, behavioral therapists, hypnotherapists and psychotherapists in treating these conditions, yet they rarely form a part of the therapeutic team, and these treatment modalities are rarely offered as part of the therapeutic management. There has been little examination of different models of care for FGIDs. We hypothesize that multi-disciplinary integrated care is superior to standard specialist-based care in the treatment of functional gut disorders.

METHODS

The "MANTRA" (Multidisciplinary Treatment for Functional Gut Disorders) study compares comprehensive multi-disciplinary outpatient care with standard hospital outpatient care. Consecutive new referrals to the gastroenterology and colorectal outpatient clinics of a single secondary and tertiary care hospital of patients with an FGID, defined by the Rome IV criteria, will be included. Patients will be prospectively randomized 2:1 to multi-disciplinary (gastroenterologist, gut-hypnotherapist, psychiatrist, behavioral therapist ('biofeedback') and dietician) or standard care (gastroenterologist or colorectal surgeon). Patients are assessed up to 12 months after completing treatment. The primary outcome is an improvement on a global assessment scale at the end of treatment. Symptoms, quality of life, psychological well-being, and healthcare costs are secondary outcome measures.

DISCUSSION

There have been few studies examining how best to deliver care for functional gut disorders. The MANTRA study will define the clinical and cost benefits of two different models of care for these highly prevalent disorders.

TRIAL REGISTRATION NUMBER

Clinicaltrials.govNCT03078634 Registered on Clinicaltrials.gov, completed recruitment, registered on March 13th 2017. Ethics and Dissemination: Ethical approval has been received by the St Vincent's Hospital Melbourne human research ethics committee (HREC-A 138/16). The results will be disseminated in peer-reviewed journals and presented at international conferences. Protocol version 1.2.

Cognitive behavioral therapy with interoceptive exposure and complementary video materials for irritable bowel syndrome (IBS): protocol for a multicenter randomized controlled trial in Japan

Background

There is growing evidence of the treatment efficacy of cognitive behavioral therapy (CBT) for irritable bowel syndrome (IBS). CBT is recommended by several practice guidelines for patients with IBS if lifestyle advice or pharmacotherapy has been ineffective. Manual-based CBT using interoceptive exposure (IE), which focuses on the anxiety response to abdominal symptoms, has been reported to be more effective than other types of CBT. One flaw of CBT use in general practice is that it is time and effort consuming for therapists. Therefore, we developed a set of complementary video materials that include psycho-education and homework instructions for CBT patients, reducing time spent in face-to-face sessions while maintaining treatment effects. The purpose of this study is to examine the effects of CBT-IE with complementary video materials (CBT-IE-w/vid) in a multicenter randomized controlled trial (RCT).

Methods

This study will be a multicenter, parallel-design RCT. Participants diagnosed with IBS according to the Rome IV diagnostic criteria will be randomized to either the treatment as usual (TAU) group or the CBT-IE-w/vid + TAU group. CBT-IE-w/vid consists of 10 sessions (approximately 30 min face-to-face therapy + viewing a video prior to each session). Patients in the CBT-IE-w/vid group will be instructed to pre- view 3- to 13-min videos at home prior to each face-to-face therapy visit at a hospital. The primary outcome is the severity of IBS symptoms. All participants will be assessed at baseline, mid-treatment, post-treatment, and follow-up (3 months after post assessment). The sample will include 60 participants in each group.

Discussion

To our knowledge, this study will be the first RCT of manual-based CBT for IBS in Japan. By using psycho-educational video materials, the time and cost of therapy will be reduced. Manual based CBTs for IBS have not been widely adopted in Japan to date. If our CBT-IE-w/vid program is confirmed to be more effective than TAU, it will facilitate dissemination of cost-effective manual-based CBT in clinical settings.

Trial registration

The trial was registered to the University Hospital Medical Information Network Clinical Trial Registry: UMIN, No. UMIN000030620 (Date of registration: December 28, 2017).

Enkephalinase inhibitors, potential therapeutics for the future treatment of diarrhea predominant functional gastrointestinal disorders

The endogenous opioid system (EOS) is considered being a crucial element involved in the pathophysiology of irritable bowel syndrome (IBS) as it regulates gastrointestinal (GI) homeostasis through modulation of motility and water and ion secretion/absorption. Along with opioid receptors (ORs), the following components of EOS can be distinguished: 1. endogenous opioid peptides (EOPs), namely enkephalins, endorphins, endomorphins and dynorphins, and 2. peptidases, which regulate the metabolism (synthesis and degradation) of EOPs. Enkephalins, which are δ-opioid receptors agonists, induce significant effects in the GI tract as they act as potent pro-absorptive neurotransmitters. The action of enkephalins and other EOPs is limited, since EOPs are easily and rapidly inactivated by a natural metalloendopeptidase (enkephalinase/neprilysin) and aminopeptidase N. Studies show that the activity of EOPs can be enhanced by inhibition of these enzymes. In this review, we discuss the antidiarrheal and antinociceptive potential of enkephalinase inhibitors. Furthermore, our review is to answer the question whether enkephalinase inhibitors may be helpful in the future treatment of diarrhea predominant functional GI disorders.

Emotional awareness and expression training improves irritable bowel syndrome: A randomized controlled trial

BACKGROUND

Current clinical guidelines identify several psychological treatments for irritable bowel syndrome (IBS). IBS patients, however, have elevated trauma, life stress, relationship conflicts, and emotional avoidance, which few therapies directly target. We tested the effects of emotional awareness and expression training (EAET) compared to an evidence-based comparison condition-relaxation training-and a waitlist control condition.

METHODS

Adults with IBS (N=106; 80% female, Mean age=36 years) were randomized to EAET, relaxation training, or waitlist control. Both EAET and relaxation training were administered in three, weekly, 50-minute, individual sessions. All patients completed the IBS Symptom Severity Scale (primary outcome), IBS Quality of Life, and Brief Symptom Inventory (anxiety, depressive, and hostility symptoms) at pretreatment and at 2 weeks posttreatment and 10 weeks follow-up (primary endpoint).

KEY RESULTS

Compared to waitlist controls, EAET, but not relaxation training, significantly reduced IBS symptom severity at 10-week follow-up. Both EAET and relaxation training improved quality of life at follow-up. Finally, EAET did not reduce psychological symptoms, whereas relaxation training reduced depressive symptoms at follow-up (and anxiety symptoms at posttreatment).

CONCLUSIONS & INFERENCES

Brief emotional awareness and expression training that targeted trauma and emotional conflicts reduced somatic symptoms and improved quality of life in patients with IBS. This emotion-focused approach may be considered an additional treatment option for IBS, although research should compare EAET to a full cognitive-behavioral protocol and determine which patients are best suited for each approach. Registered at clinicaltrials.gov (NCT01886027).

Bacillus coagulans MTCC 5856 supplementation in the management of diarrhea predominant Irritable Bowel Syndrome: a double blind randomized placebo controlled pilot clinical study

BACKGROUND

Bacillus coagulans MTCC 5856 has been marketed as a dietary ingredient, but its efficacy in diarrhea predominant irritable bowel syndrome (IBS) condition has not been clinically elucidated till date. Thus, a double blind placebo controlled multi-centered trial was planned to evaluate the safety and efficacy of B. coagulans MTCC 5856 in diarrhea predominant IBS patients.

METHODS

Thirty six newly diagnosed diarrhea predominant IBS patients were enrolled in three clinical centres. Along with standard care of treatment, 18 patients in group one received placebo while in group two 18 patients received B. coagulans MTCC 5856 tablet containing 2 × 10(9) cfu/day as active for 90 days. Clinical symptoms of IBS were considered as primary end point measures and were evaluated through questionnaires. The visual analog scale (VAS) was used for abdominal pain. Physician's global assessment and IBS quality of life were considered as secondary efficacy measures and were monitored through questionnaires.

RESULTS

Laboratory parameters, anthropometric and vital signs were within the normal clinical range during the 90 days of supplementation in placebo and B. coagulans MTCC 5856 group. There was a significant decrease in the clinical symptoms like bloating, vomiting, diarrhea, abdominal pain and stool frequency in a patient group receiving B. coagulans MTCC 5856 when compared to placebo group (p < 0.01). Similarly, disease severity also decreased and the quality of life increased in the patient group receiving B. coagulans MTCC 5856 when compared to placebo group.

CONCLUSIONS

The study concluded that the B. coagulans MTCC 5856 at a dose of 2 × 10(9) cfu/day along with standard care of treatment was found to be safe and effective in diarrhea predominant IBS patients for 90 days of supplementation. Hence, B. coagulans MTCC 5856 could be a potential agent in the management of diarrhea predominant IBS patients.

Colectomy for constipation: time trends and impact based on the US Nationwide Inpatient Sample, 1998-2011

BACKGROUND

Current guidelines include subtotal colectomy as treatment for refractory slow transit constipation.

AIM

To use the US Nationwide Inpatient Sample (NIS) (1998-2011) and longitudinal data from the State Inpatient Database (2005-2011), comparable to NIS, to examine colectomy rates, in-hospital morbidity and emergency department (ED) visits or readmissions among patients treated for constipation.

METHODS

Colectomies for any reason were identified based on the primary procedural code (ICD-9-CM 45.8x). Index hospitalisations were defined by the primary diagnosis of constipation (ICD-9-CM 564.x) associated with the primary procedural code for colectomy (ICD-9-CM45.8x) after exclusion of other diseases associated with colectomy. Demographic variables, comorbidities, complications and adverse events during the hospitalisation were captured, and ED visits and admissions were recorded for periods before and after colectomy.

RESULTS

Nationally, colectomies for constipation rose from 104 procedures in 1998 (1.2% of annual colectomies) to 311 in 2011 (2.4% of annual colectomies). While there were no perioperative deaths, perioperative complications occurred in 42.7% of patients during the index hospitalisation. Longitudinal data were analysed for 181 patients, with similar perioperative complications and a readmission rate of 28.9% within the first 30 days after the index hospitalisation. Resource utilisation was tracked for a median time of 630 (0-2386) before and 463 (0-2204) days after colectomy with unchanged ED visits (median: 2 vs. 2, P = 0.21), but increased hospitalisations (median: 1 vs. 2, P = 0.003).

CONCLUSIONS

Colectomy rates for constipation are rising, are associated with significant morbidity and do not decrease resource utilisation, raising questions about the true benefit of surgery for slow transit constipation.

Imaging brain mechanisms in chronic visceral pain

Chronic visceral pain syndromes are important clinical problems with largely unmet medical needs. Based on the common overlap with other chronic disorders of visceral or somatic pain, mood and affect, and their responsiveness to centrally targeted treatments, an important role of central nervous system in their pathophysiology is likely. A growing number of brain imaging studies in irritable bowel syndrome, functional dyspepsia, and bladder pain syndrome/interstitial cystitis has identified abnormalities in evoked brain responses, resting state activity, and connectivity, as well as in gray and white matter properties. Structural and functional alterations in brain regions of the salience, emotional arousal, and sensorimotor networks, as well as in prefrontal regions, are the most consistently reported findings. Some of these changes show moderate correlations with behavioral and clinical measures. Most recently, data-driven machine-learning approaches to larger data sets have been able to classify visceral pain syndromes from healthy control subjects. Future studies need to identify the mechanisms underlying the altered brain signatures of chronic visceral pain and identify targets for therapeutic interventions.

Pinaverium Reduces Symptoms of Irritable Bowel Syndrome in a Multicenter, Randomized, Controlled Trial

BACKGROUND & AIMS

Pinaverium bromide (pinaverium) is an antispasmodic commonly used to treat irritable bowel syndrome (IBS), but there has been no convincing evidence for its effectiveness and safety. We evaluated these in a prospective, double-blind, placebo-controlled trial.

METHODS

Patients with IBS, based on Rome III criteria, were assigned randomly to groups given pinaverium (50 mg, 3 times/day; n = 218) or placebo (3 times/day; n = 209) at 4 hospitals in China, from August 2012 through December 2013. The primary end points were reductions in abdominal pain and Bristol stool score. Secondary end points were reductions in pain and stool frequencies and abdominal discomfort and its frequency. We also evaluated changes in IBS global symptom scores and the number of adverse effects.

RESULTS

Based on an intention-to-treat analysis, a significantly larger proportion of patients receiving pinaverium met either of the primary end points (50.0% met an end point at week 2, and 77.5% met an end point at week 4), compared with placebo (P < .001). Pinaverium reduced at least 1 secondary end point in significantly more patients receiving pinaverium (76.1% had a reduction at week 2, and 91.7% had a reduction at week 4) than placebo (P < .001). Based on symptom scores, significantly higher percentages of patients receiving pinaverium believed that their IBS symptoms improved (60%) than in the placebo group (34%; P < .001); 29% of patients in the pinaverium group believed that their IBS symptoms stayed the same (29%) and 11% said they worsened. Pinaverium was not associated with severe adverse effects; common side effects included nausea (3.7%), dizziness (3.2%), increased blood pressure (2.3%), and abdominal discomfort (2.3%).

CONCLUSIONS

Based on a controlled trial, pinaverium reduces symptoms of IBS. It can be considered a first-line treatment for IBS.

TRIAL REGISTRATION

NCT01641224 (www.ClinicalTrials.gov).

Evidence-based clinical practice guidelines for irritable bowel syndrome

New strategies for the care of irritable bowel syndrome (IBS) are developing and several novel treatments have been globally produced. New methods of care should be customized geographically because each country has a specific medical system, life style, eating habit, gut microbiota, genes and so on. Several clinical guidelines for IBS have been proposed and the Japanese Society of Gastroenterology (JSGE) subsequently developed evidence-based clinical practice guidelines for IBS. Sixty-two clinical questions (CQs) comprising 1 definition, 6 epidemiology, 6 pathophysiology, 10 diagnosis, 30 treatment, 4 prognosis, and 5 complications were proposed and statements were made to answer to CQs. A diagnosis algorithm and a three-step treatment was provided for patients with chronic abdominal pain or abdominal discomfort and/or abnormal bowel movement. If more than one alarm symptom/sign, risk factor and/or routine examination is positive, colonoscopy is indicated. If all of them, or the subsequent colonoscopy, are/is negative, Rome III or compatible criteria is applied. After IBS diagnosis, step 1 therapy consisting of diet therapy, behavioral modification and gut-targeted pharmacotherapy is indicated for four weeks. Non-responders to step 1 therapy proceed to the second step that includes psychopharmacological agents and simple psychotherapy for four weeks. In the third step, for patients non-responsive to step 2 therapy, a combination of gut-targeted pharmacotherapy, psychopharmacological treatments and/or specific psychotherapy is/are indicated. Clinical guidelines and consensus for IBS treatment in Japan are well suited for Japanese IBS patients; as such, they may provide useful insight for IBS treatment in other countries around the world.

Prokinetic effects of mirtazapine on gastrointestinal transit

Mirtazapine is a noradrenergic and specific serotonergic antidepressant. The aim of this study was to investigate the effects of mirtazapine on gastrointestinal motility in dogs, including solid gastric emptying, antral and small intestinal contractions, and small intestinal and colonic transit. Six dogs were implanted with two cannulas located at the duodenum and the ascending colon; another six dogs were implanted with gastric cannula 6 cm proximal to the pylorus. Mirtazapine 45 mg was administered orally 90 min before the study. We found that 1) Mirtazapine accelerated gastric emptying during the entire 3 h in normal dogs (P < 0.04) and accelerated delayed gastric emptying induced by rectal distention (P < 0.04). 2) Mirtazapine restored impaired gastric tone and accommodation induced by rectal distention (P < 0.05). 3) No significant changes were noted in small intestinal contractions or transit with mirtazapine (P > 0.1). 4) Mirtazapine accelerated colonic transit at 2 and 4 h but not 6 h. The geometric center was increased from 1.9 ± 0.6 to 3.0 ± 0.5 and 3.9 ± 0.5 to 4.7 ± 0.1 at 2 and 4 h respectively (P = 0.04 vs. corresponding control). In conclusion, mirtazapine improves gastric emptying in healthy dogs and normalizes rectal distention-induced delay in gastric emptying and accelerates colon but not small intestinal transit in healthy dogs. Clinical studies are warranted to assess the effects of mirtazapine on gastrointestinal motility and sensory functions in patients with functional gastrointestinal diseases.

Polar vectors as a method for evaluating the effectiveness of irritable bowel syndrome treatments: an analysis with pinaverium bromide 100mg plus simethicone 300mg po bid

BACKGROUND

Irritable Bowel Syndrome (IBS) is a disorder characterized by abdominal pain or discomfort associated with changes in bowel habit. Currently there are no objective outcome measures for evaluating the effectiveness of treatments for this disorder.

AIMS

To determine the usefulness of a method of analysis that employs polar vectors to evaluate the effectiveness of IBS treatments.

METHODS

Data from a Phase IV clinical study with 1677 active IBS-Rome III patients who received 100mg of pinaverium bromide+300mg of simethicone (PB+S) po bid for a period of four weeks were used for the analysis. Using the Bristol Stool Scale as a reference, the consistency and frequency of each type of bowel movement were recorded weekly in a Bristol Matrix (BM) and the data were expressed as polar vectors.

RESULTS

The analysis showed a differential response to the PB+S treatment among the IBS subtypes: in reference to the IBS with constipation subtype, the magnitude of the vector increased from 10.2 to 12.5, reaching maximum improvement at two weeks of treatment (p<0.05, Scheffé). In the IBS with diarrhea and mixed IBS subtypes, the magnitude of the vector decreased from 19 to 14 (p<0.05) and from 16.5 to 13 (p<0.05), respectively, with continuous improvement for a period of four weeks. There was no definable vectorial pattern in the unsubtyped IBS group.

CONCLUSIONS

Analysis with polar vectors enables treatment response to be measured in different IBS subtypes. All the groups showed improvement with PB+S, but each one had its own characteristic response in relation to vector magnitude and direction. The proposed method can be implemented in clinical studies to evaluate the efficacy of IBS treatments.

The rising tide of cholecystectomy for biliary dyskinesia

BACKGROUND

Expert consensus defines biliary dyskinesia as a rare disorder of the gall-bladder characterised by pain and impaired gall-bladder function.

AIM

To determine trends in cholecystectomy rates for biliary dyskinesia in the United States.

METHODS

As biliary dyskinesia does not have a distinct diagnosis code, the narrative diagnoses for patients were reviewed and abstracted for 200 patients treated for the most commonly used diagnosis codes for biliary dyskinesia (validation sample). Time trends in cholecystectomies and hospitalisations for biliary diseases were assessed using the Nationwide Inpatient Sample (Agency for Healthcare Research and Quality) based on codes for cholecystectomy and diagnosis codes for different biliary disorders.

RESULTS

In the validation sample, biliary dyskinesia accounted for 81% of the patients with ICD-9 code 575.8 (gall-bladder disease not elsewhere specified). Between 1997 and 2010, admissions for acute cholecystitis and complications of gallstone disease decreased slightly, whereas admissions with the primary diagnosis code ICD-9 575.8 tripled. This rise was most pronounced in the paediatric population (700% increase), with biliary dyskinesia accounting for more than 10% of cholecystectomies. Compared with acute biliary diseases, significantly more of the elective hospitalisations were covered by private insurances.

CONCLUSIONS

Practice patterns differ from expert opinion, with biliary dyskinesia accounting for an increasing fraction of cholecystectomies. The rise in these elective interventions is associated with a shift to a younger, low risk and predominantly privately insured population. Considering the benign nature of biliary dyskinesia, it is time to reassess the need for operative interventions, which have never been compared with active conservative therapy.

Randomised clinical trials: linaclotide phase 3 studies in IBS-C - a prespecified further analysis based on European Medicines Agency-specified endpoints

BACKGROUND

Treatment options that improve overall symptoms of irritable bowel syndrome with constipation (IBS-C) are lacking.

AIM

A prespecified further analysis to evaluate the efficacy and safety of linaclotide, a guanylate cyclase C agonist, in patients with IBS-C, based on efficacy parameters prespecified for European Medicines Agency (EMA) submission.

METHODS

Two randomised, double-blind, multicentre Phase 3 trials investigated once-daily linaclotide (290 μg) for 12 weeks (Trial 31) or 26 weeks (Trial 302) in patients with IBS-C. Prespecified primary endpoints were the EMA-recommended co-primary endpoints: (i) 12-week abdominal pain/discomfort responders [≥30% reduction in mean abdominal pain and/or discomfort score (11-point scales), with neither worsening from baseline, for ≥6 weeks] and (ii) 12-week IBS degree-of-relief responders (symptoms 'considerably' or 'completely' relieved for ≥6 weeks).

RESULTS

Overall, 803 (Trial 31) and 805 patients (Trial 302) were randomised. A significantly greater proportion of linaclotide-treated vs. placebo-treated patients were 12-week abdominal pain/discomfort responders (Trial 31: 54.8% vs. 41.8%; Trial 302: 54.1% vs. 38.5%; P < 0.001) and IBS degree-of-relief responders (Trial 31: 37.0% vs. 18.5%; Trial 302: 39.4% vs. 16.6%; P < 0.0001). Similarly, significantly more linaclotide- vs. placebo-treated patients were responders for ≥13 weeks in Trial 302 (abdominal pain/discomfort: 53.6% vs. 36.0%; IBS degree-of-relief: 37.2% vs. 16.9%; P < 0.0001). The proportion of sustained responders (co-primary endpoint responders plus responders for ≥2 of the last 4 weeks of treatment) was also significantly greater with linaclotide vs. placebo in both trials (P < 0.001).

CONCLUSION

Linaclotide treatment significantly improved abdominal pain/discomfort and degree-of-relief of IBS-C symptoms compared with placebo over 12 and 26 weeks.

TRIAL REGISTRATION

ClinicalTrials.gov (identifiers: NCT00948818 and NCT00938717).

The Irritable Bowel Syndrome Outcome Study (IBSOS): rationale and design of a randomized, placebo-controlled trial with 12 month follow up of self- versus clinician-administered CBT for moderate to severe irritable bowel syndrome

Irritable bowel syndrome is a common, oftentimes disabling, gastrointestinal disorder whose full range of symptoms has no satisfactory medical or dietary treatment. One of the few empirically validated treatments includes a specific psychological therapy called cognitive behavior therapy which, if available, is typically administered over several months by trained practitioners in tertiary care settings. There is an urgent need to develop more efficient versions of CBT that require minimal professional assistance but retain the efficacy profile of clinic based CBT. The Irritable Bowel Syndrome Outcome Study (IBSOS) is a multicenter, placebo-controlled randomized trial to evaluate whether a self-administered version of CBT is, at least as efficacious as standard CBT and more efficacious than an attention control in reducing core GI symptoms of IBS and its burden (e.g. distress, quality of life impairment, etc.) in moderately to severely affected IBS patients. Additional goals are to assess, at quarterly intervals, the durability of treatment response over a 12 month period; to identify clinically useful patient characteristics associated with outcome as a way of gaining an understanding of subgroups of participants for whom CBT is most beneficial; to identify theory-based change mechanisms (active ingredients) that explain how and why CBT works; and evaluate the economic costs and benefits of CBT. Between August 2010 when IBSOS began recruiting subjects and February 2012, the IBSOS randomized 171 of 480 patients. Findings have the potential to improve the health of IBS patients, reduce its social and economic costs, conserve scarce health care resources, and inform evidence-based practice guidelines.

Clinical trial: Lactobacillus plantarum 299v (DSM 9843) improves symptoms of irritable bowel syndrome

AIM: To assess the symptomatic efficacy of Lactobacillus plantarum 299v (L. plantarum 299v) (DSM 9843) for the relief of abdominal symptoms in a large subset of irritable bowel syndrome (IBS) patients fulfilling the Rome III criteria.

METHODS: In this double blind, placebo-controlled, parallel-designed study, subjects were randomized to daily receive either one capsule of L. plantarum 299v (DSM 9843) or placebo for 4 wk. Frequency and intensity of abdominal pain, bloating and feeling of incomplete rectal emptying were assessed weekly on a visual analogue scale while stool frequency was calculated.

RESULTS: Two hundred and fourteen IBS patients were recruited. After 4 wk, both pain severity (0.68 + 0.53 vs 0.92 + 0.57, P < 0.05) and daily frequency (1.01 + 0.77 vs 1.71 + 0.93, P < 0.05) were lower with L. plantarum 299v (DSM 9843) than with placebo. Similar results were obtained for bloating. At week 4, 78.1 % of the patients scored the L. plantarum 299v (DSM 9843) symptomatic effect as excellent or good vs only 8.1 % for placebo (P < 0.01).

CONCLUSION: A 4-wk treatment with L. plantarum 299v (DSM 9843) provided effective symptom relief, particularly of abdominal pain and bloating, in IBS patients fulfilling the Rome III criteria.

Irritable bowel syndrome: methods, mechanisms, and pathophysiology. Genetic epidemiology and pharmacogenetics in irritable bowel syndrome

The objectives of this review are twofold. Our first objective is to evaluate the evidence supporting a role for genetics in irritable bowel syndrome (IBS). Specific examples of the associations of genetic variation and symptoms, syndromes, and intermediate phenotypes, including neurotransmitter (serotonergic, α(2)-adrenergic, and cannabinoid) mechanisms, inflammatory pathways (IL-10, TNFα, GNβ3, and susceptibility loci involved in Crohn's disease), and bile acid metabolism, are explored. The second objective is to review pharmacogenetics in IBS, with the focus on cytochrome P-450 metabolism of drugs used in IBS, modulation of motor and sensory responses to serotonergic agents based on the 5-hydroxytryptamine (5-HT) transporter-linked polymorphic region (5-HTTLPR) and 5-HT(3) genetic variants, responses to a nonselective cannabinoid agonist (dronabinol) based on cannabinoid receptor (CNR1) and fatty acid amide hydrolase (FAAH) variation, and responses to a bile acid (sodium chenodeoxycholate) and bile acid binding (colesevelam) based on klothoβ (KLB) and fibroblast growth factor receptor 4 (FGFR4) variation. Overall, there is limited evidence of a genetic association with IBS; the most frequently studied association is with 5-HTTLPR, and the most replicated association is with TNF superfamily member 15. Most of the pharmacogenetic associations are reported with intermediate phenotypes in relatively small trials, and confirmation in large clinical trials using validated clinical end points is still required. No published genome-wide association studies in functional gastrointestinal or motility disorders have been published.

Efficacy and safety profile of LCR35 complete freeze-dried culture in irritable bowel syndrome: A randomized, double-blind study

AIM: To assess the effects and safety of Lactobacillus casei rhamnosus LCR35 complete freeze-dried culture (LCR35) in patients suffering from irritable bowel syndrome (IBS).

METHODS: A randomized, double-blind pilot study was performed in 50 patients complaining of IBS symptoms complying with Rome III criteria. Patients were allocated to receive either LCR35 (n = 25) at a minimum daily dose of 6 × 10⁸ colony forming units or placebo (n = 25) for 4 wk. At inclusion, after treatment and 2 wk later, patients completed the IBS severity scale. Change from baseline in the IBS severity score at the end of treatment was the primary efficacy criterion. Changes were compared between groups in the whole population and in IBS subtypes (IBS with predominance of constipation, IBS with predominance of diarrhoea, mixed IBS, unsubtyped IBS). The presence of lactobacillus casei rhamnosus in stools was investigated at inclusion and at the end of treatment. The gastrointestinal quality of life questionnaire and the hospital anxiety and depression (HAD) scale were also completed.

RESULTS: Both groups were balanced for baseline characteristics. In 85% of patients, stool analyses showed that lactobacillus casei rhamnosus able to survive in the digestive tract. In the whole population, improvements in the IBS severity score did not differ significantly between treatments with a 25% decrease after 4-wk treatment, and a 15% decrease from baseline 2 wk later in both groups. In IBS subgroups, statistical analysis could not be performed due to small sample size, but a clinical response in favour of LCR35 was observed in IBS patients with predominance of diarrhoea: no change in the symptom severity score was seen with the placebo after 4 wk treatment, whereas a clinically relevant decrease occurred with LCR35 (-37% vs -3%). Furthermore, in spite of an increase in symptom intensity, the IBS severity score was maintained below the baseline value 2 wk later with LCR35 (-19% from baseline), whilst a slight 5% increase from baseline was observed with placebo. In the IBS subgroup with predominance of diarrhoea only, a clinically relevant decrease in abdominal pain severity score (-36%) was observed with LCR35, whereas no change occurred with placebo. In mixed IBS patients, the 20% and 30% decreases in the IBS severity score observed after treatment with LCR35 and placebo, respectively, were maintained 2 wk later in both groups. A clinical response slightly in favour of placebo was observed at the end of the treatment period in IBS patients with predominance of constipation (-41% vs -20%) and unsubtyped IBS patients (-47% vs -17%), with the same value maintained 2 wk later. In both groups, no clinically relevant changes were observed either for the gastrointestinal quality of life index or HAD score. Thus, these results suggest that sub-grouping of IBS patients may be important for optimizing treatment responses by the physician.

CONCLUSION: This pilot study suggests that LCR35 could have some efficacy in IBS patients complaining of diarrhoea. These preliminary results need to be confirmed in larger studies.

Review article: probiotics for the treatment of irritable bowel syndrome--focus on lactic acid bacteria

BACKGROUND

Irritable bowel syndrome (IBS) is a poorly understood, yet highly prevalent functional gastrointestinal disorder (FGID). The withdrawal, due to adverse events, of a number of pharmacological agents that were approved for the treatment of IBS has left a therapeutic vacuum for patients suffering from the disorder.

AIM

To review, summarise and critically evaluate current knowledge of lactic acid bacteria (LAB) used to treat IBS.

METHODS

We assessed a comprehensive range of relevant literature from Pubmed, Medline and online sources based on our definition of LAB which included both typical and atypical species, covering Lactobacilli, Bifidobacteria, Enterococci, Streptococci and Bacilli.

RESULTS

Of the 42 trials evaluated examining the efficacy of LAB in IBS, 34 reported beneficial effects in at least one of the endpoints or symptoms examined, albeit with tremendous variation in both the magnitude of effect and the choice of outcome under consideration. However, numerous concerns have been expressed over deficits of trial design and execution relating to strain selection, optimum dosage, mode of action, safety and long-term tolerability in a disorder that can persist throughout the lifetime of affected individuals.

CONCLUSIONS

Progress in the field will require an improved understanding of how the microbiota impacts on health and disease, adequately powered long-term multicentre trials and the embracing of bench to bedside approaches. Recent incremental advances suggest these areas are being addressed and that the future holds much promise for the use of lactic acid bacteria in the treatment of irritable bowel syndrome.

Rifaximin for the treatment of irritable bowel syndrome

INTRODUCTION

Few therapeutic options are available for irritable bowel syndrome (IBS). Lubiprostone is approved by the FDA for IBS with constipation, and alosetron in IBS with diarrhea (IBS-D). It has been proposed that alterations in the bowel microflora may play a role in the pathophysiology of IBS, and that modulation of the microflora holds therapeutic potential. Rifaximin is a nonsystemic antibiotic that has shown efficacy in IBS.

AREAS COVERED

This narrative review covers the treatment options available for IBS-D and focuses on rifaximin. Rifaximin pharmacodynamics, clinical pharmacology and results of clinical studies from proof of concept to the latest Phase III and retreatment studies in IBS are summarized. Challenges to rifaximin use, safety issues and regulatory data are also discussed.

EXPERT OPINION

The evidence supports rifaximin as an emerging treatment for IBS. Strategies for appropriate patient selection need to be further developed, and continued efficacy of rifaximin over repeated treatment courses needs to be better characterized.

LX-1031, a tryptophan 5-hydroxylase inhibitor, and its potential in chronic diarrhea associated with increased serotonin

LX-1031 is an oral, small molecule tryptophan 5-hydroxylase (TPH) inhibitor that reduces serotonin (5-HT) synthesis peripherally. It has potential for illnesses characterized by excess 5-HT, such as diarrhea-predominant irritable bowel syndrome (IBS-D) and carcinoid diarrhea. In vitro, inhibition of TPH1 occurred in 10(-8) -10(-7) mol L(-1) range. In vivo in rodents, LX-1031 has no effect on brain 5-HT while dose-dependently reducing 5-HT, particularly in the small bowel. After oral LX1031 in humans, systemic exposure is very low, plasma concentrations are linear in dose range 250-750 mg q.i.d.; the median T(1/2) for elimination is ∼ 20 h, and repeat administration for 14 days doubles C(max) . In ascending-single-dose and multiple-dose (14 days) trials in healthy volunteers, LX-1031, 2-4 g day(-1) significantly reduced urinary 5-hydroxyindoleacetic acid (5-HIAA) starting by Day 5, and persisting over the 14 day exposure. There are no dose-limiting toxicities in healthy subjects or remarkable adverse effects in clinical trials to date. Over a 28-day treatment period, LX-1031 was associated with improved weekly global scores (2/4 weeks) and improved stool consistency with lower urinary 5-HIAA excretion. LX-1031 appears promising for chronic diarrhea associated with increased 5-HT expression including IBS-D. Optimal doses, efficacy and safety in IBS clinical trials need to be fully elucidated; low systemic exposure, selectivity for TPH1 over TPH2, and lack of effect on brain 5-HT in several species suggest that LX-1031 is unlikely to cause affective disorders.

The brain-gut axis in abdominal pain syndromes

The importance of bidirectional brain-gut interactions in gastrointestinal (GI) illness is increasingly recognized, most prominently in the area of functional GI syndromes such as irritable bowel syndrome (IBS), functional dyspepsia, and functional chest pain. The brain receives a constant stream of interoceptive input from the GI tract, integrates this information with other interoceptive information from the body and with contextual information from the environment, and sends an integrated response back to various target cells within the GI tract. This system is optimized to assure homeostasis of the GI tract during physiological perturbations and to adapt GI function to the overall state of the organism. In health, the great majority of interoceptive information reaching the brain is not consciously perceived but serves primarily as input to autonomic reflex pathways. In patients with functional abdominal pain syndromes, conscious perception of interoceptive information from the GI tract, or recall of interoceptive memories of such input, can occur in the form of constant or recurrent discomfort or pain. This is often associated with alterations in autonomic nervous system output and with emotional changes. A model is proposed that incorporates reported peripheral and central abnormalities in patients with IBS, extrapolates similar alterations in brain-gut interactions to patients with other chronic abdominal pain syndromes, and provides novel treatment targets.

Interplay between inflammation, immune system and neuronal pathways: Effect on gastrointestinal motility

Sepsis is a systemic inflammatory response representing the leading cause of death in critically ill patients, mostly due to multiple organ failure. The gastrointestinal tract plays a pivotal role in the pathogenesis of sepsis-induced multiple organ failure through intestinal barrier dysfunction, bacterial translocation and ileus. In this review we address the role of the gastrointestinal tract, the mediators, cell types and transduction pathways involved, based on experimental data obtained from models of inflammation-induced ileus and (preliminary) clinical data. The complex interplay within the gastrointestinal wall between mast cells, residential macrophages and glial cells on the one hand, and neurons and smooth muscle cells on the other hand, involves intracellular signaling pathways, Toll-like receptors and a plethora of neuroactive substances such as nitric oxide, prostaglandins, cytokines, chemokines, growth factors, tryptases and hormones. Multidirectional signaling between the different components in the gastrointestinal wall, the spinal cord and central nervous system impacts inflammation and its consequences. We propose that novel therapeutic strategies should target inflammation on the one hand and gastrointestinal motility, gastrointestinal sensitivity and even pain signaling on the other hand, for instance by impeding afferent neuronal signaling, by activation of the vagal anti-inflammatory pathway or by the use of pharmacological agents such as ghrelin and ghrelin agonists or drugs interfering with the endocannabinoid system.

Diagnosis and management of IBS

IBS is a common gastrointestinal condition characterized by chronic or recurrent abdominal pain associated with altered bowel habits. IBS is considered a functional bowel disorder (that is, not defined by structural or biochemical abnormalities) and is diagnosed using symptom-based criteria. Limited and judicious use of diagnostic testing is recommended, particularly in patients with typical symptoms of IBS without alarm signs and symptoms. Management of IBS is based on a multifactorial approach and includes establishment of an effective patient-provider relationship, education, reassurance, dietary alterations, pharmacotherapy, behavioral and psychological treatment. Patient-centered care is recommended, in which management is focused on the patient's most bothersome and impactful symptoms, their preferences and previous experiences with treatment, and addressing factors associated with the onset and exacerbation of symptoms. Pharmacotherapy is typically targeted against the predominant symptom. This Review discusses the current evidence-based recommendations for the diagnosis and management of IBS. An improved understanding of the recommended diagnostic and therapeutic approaches for IBS will lead to greater patient satisfaction, as well as reduced health-care costs.

Challenges and prospects for pharmacotherapy in functional gastrointestinal disorders

Functional gastrointestinal disorders, such as irritable bowel syndrome and functional dyspepsia, are complex conditions with multiple factors contributing to their pathophysiology. As a consequence they are difficult to treat and have posed significant challenges to the pharmaceutical industry when trying to develop new and effective treatments. This review provides an overview of these difficulties and how the industry is reshaping its drug developmental strategies. It describes some of the more significant and encouraging advances that have occurred, and discusses how future research might embrace the opportunities provided by advances in genetic and in particular, epigenetic research.

Serotonin signaling is altered in irritable bowel syndrome with diarrhea but not in functional dyspepsia in pediatric age patients

BACKGROUND & AIMS

In adults, irritable bowel syndrome (IBS) and functional dyspepsia (FD) are chronic conditions that often start during childhood. We investigated mucosal serotonin (5-HT) signaling in children with the idea that data from subjects with a shorter history may improve our understanding of underlying pathophysiological mechanisms.

METHODS

Ninety-eight children undergoing gastroscopy or colonoscopy were studied prospectively. Biopsy specimens were evaluated for inflammation, enterochromaffin cell numbers, 5-HT content, and messenger RNA (mRNA) levels for the synthetic enzyme, tryptophan hydroxylase 1, and the serotonin transporter (SERT) were assessed by quantitative real-time reverse-transcription polymerase chain reaction.

RESULTS

Data from 12 children with IBS and 17 with FD were compared with age-matched controls (12 with rectal biopsies and 12 with gastric biopsies) and with subjects with organic disorders. In patients with FD, a small number of immune cells were observed in the gastric mucosa in half of the patients, but no abnormalities with respect to the 5-HT pathway were identified. In patients with IBS, no differences were detected between patients and controls regarding intraepithelial lymphocytes and CD3+ cells in the lamina propria although all patients showed at least a slight inflammatory infiltrate. In the IBS samples, higher 5-HT content (P < .01) and lower SERT mRNA (P < .05) were detected as compared with controls. Severe inflammation in the colonic mucosa had a high impact on 5-HT signaling with a significant decrease in enterochromaffin cells (P < .01) and 5-HT content (P < .01) and a high SERT mRNA expression (P < .01).

CONCLUSIONS

These results confirm the role of 5-HT signaling in IBS in children and argue against such a role in FD.

Management of functional abdominal pain and irritable bowel syndrome in children and adolescents

Functional abdominal pain (FAP) and irritable bowel syndrome (IBS) are among the most commonly diagnosed medical problems in pediatrics. Symptom-based Rome III criteria for FAP and IBS have been validated and help the clinician in making a positive diagnosis. The majority of patients with mild complaints improve with reassurance and time. For a distinct subset of patients with more severe and disabling illness, finding effective treatment for these disorders remains a challenge. Over the years, a wide range of therapies have been proposed and studied. The lack of a single, proven intervention highlights the complex interplay of biopsychosocial factors probably involved in the development of childhood FAP and IBS, and the need for a multidisciplinary, integrated approach. This article reviews the current literature on the efficacy of pharmacologic, dietary and psychosocial interventions for FAP and IBS in children and adolescents.

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.

Lower functional gastrointestinal disorders: evidence of abnormal colonic transit in a 287 patient cohort

BACKGROUND Abnormalities of colonic motility were reported in relatively small studies of patients with lower functional gastrointestinal disorders (FGID) including irritable bowel syndrome (IBS). The influence of gender and body mass on the observed motor pathophysiology is unclear. We sought to compare colonic transit in patients within different lower FGID subgroups and healthy controls, controlling for gender and BMI, and to determine whether BMI independently influences colonic motility. METHODS We evaluated a scintigraphic gastrointestinal and colonic transit database of 287 lower FGID patients associated with constipation (IBS-C, or functional constipation, n = 118), diarrhoea (IBS-D or functional diarrhoea, n = 139) or mixed bowel function (IBS-M, n = 30) and 170 healthy controls. We measured colon filling at 6 h (CF 6 h), and overall colonic transit at 8, 24 and 48 h. KEY RESULTS Colon filling at 6 h did not differentiate health from FGID. Colonic transit was abnormal at 24 h (GC24 of <1.50 or >3.86) in 29.7% of all lower FGID patients. There was a significant overall association between colonic transit and subject group (healthy controls and FGID subgroups) at 8 (P = 0.01), 24 (P < 0.001) and 48 h (P < 0.001) in particular for those with diarrhoea or constipation at 24 and 48 h (P < 0.05), even after adjusting for age, gender and BMI. In addition, BMI was associated with colonic transit after adjusting for age, gender and subject group. CONCLUSIONS & INFERENCES Abnormal transit is documented non-invasively with scintigraphy in 30% of lower FGID patients; transit measurement may help document pathophysiology and inform selection of therapy in lower FGID.

Reproducibility and performance characteristics of colonic compliance, tone, and sensory tests in healthy humans

BACKGROUND

The performance characteristics of colonic sensation and motility measurements are unclear.

AIM

To compare left colon compliance, tone, and sensation in males and females and to evaluate inter and intra-individual coefficients of variation (COV) in these measurements.

METHODS

Data were acquired using standard barostat methods, by one technologist, in 72 human volunteers (38 males, 18-65 years). We measured compliance, fasting tone, and sensation during baseline and post-placebo; postprandial (PP) tone was measured only post-placebo. Compliance and thresholds for first sensation, gas, and pain were measured using ascending method of limits; sensory ratings (0-100 mm VAS) using random phasic distensions at 8-36 mmHg above baseline operating pressure. Change in PP tone was measured by barostat balloon volume for the first 30 min after a 1000-kcal meal. Inter-COV was calculated as 100 (SD/mean), and intra-COV as (100 x SD delta/overall mean).

RESULTS

There were no statistically significant associations with gender for most sensory or motor data at baseline. A modest association of fasting colonic tone and gender was observed. COV are lower (20-35%) for compliance, fasting tone, pain threshold, and sensation ratings than for PP tone and threshold for first or gas sensation (>45%). COV data are similar in males and females; sensation COVs appear smaller in females than in males.

CONCLUSIONS

Testing of compliance, tone and pain, and gas sensation in left colon performs adequately to assess these functions in humans. Lower COV for sensation tests among females is relevant to plan studies of drugs intended for functional GI disorders.

Cannabinoids and the gut: new developments and emerging concepts

Cannabis has been used to treat gastrointestinal (GI) conditions that range from enteric infections and inflammatory conditions to disorders of motility, emesis and abdominal pain. The mechanistic basis of these treatments emerged after the discovery of Delta(9)-tetrahydrocannabinol as the major constituent of Cannabis. Further progress was made when the receptors for Delta(9)-tetrahydrocannabinol were identified as part of an endocannabinoid system, that consists of specific cannabinoid receptors, endogenous ligands and their biosynthetic and degradative enzymes. Anatomical, physiological and pharmacological studies have shown that the endocannabinoid system is widely distributed throughout the gut, with regional variation and organ-specific actions. It is involved in the regulation of food intake, nausea and emesis, gastric secretion and gastroprotection, GI motility, ion transport, visceral sensation, intestinal inflammation and cell proliferation in the gut. Cellular targets have been defined that include the enteric nervous system, epithelial and immune cells. Molecular targets of the endocannabinoid system include, in addition to the cannabinoid receptors, transient receptor potential vanilloid 1 receptors, peroxisome proliferator-activated receptor alpha receptors and the orphan G-protein coupled receptors, GPR55 and GPR119. Pharmacological agents that act on these targets have been shown in preclinical models to have therapeutic potential. Here, we discuss cannabinoid receptors and their localization in the gut, the proteins involved in endocannabinoid synthesis and degradation and the presence of endocannabinoids in the gut in health and disease. We focus on the pharmacological actions of cannabinoids in relation to GI disorders, highlighting recent data on genetic mutations in the endocannabinoid system in GI disease.

Review article: new receptor targets for medical therapy in irritable bowel syndrome

BACKGROUND

Despite setbacks to the approval of new medications for the treatment of irritable bowel syndrome, interim guidelines on endpoints for irritable bowel syndrome (IBS) trials have enhanced interest as new targets for medical therapy are proposed based on novel mechanisms or chemical entities.

AIMS

To review the approved lubiprostone, two targets that are not meeting expectations (tachykinins and corticotrophin-releasing hormone), the efficacy and safety of new 5-HT(4) agonists, intestinal secretagogues (chloride channel activators, and guanylate cyclase-C agonists), bile acid modulation, anti-inflammatory agents and visceral analgesics.

METHODS

Review of selected articles based on PubMed search and clinically relevant information on mechanism of action, safety, pharmacodynamics and efficacy.

RESULTS

The spectrum of peripheral targets of medical therapy addresses chiefly the bowel dysfunction of IBS and these effects are associated with pain relief. The pivotal mechanisms responsible for the abdominal pain or visceral sensation in IBS are unknown. The new 5-HT(4) agonists are more specific than older agents and show cardiovascular safety to date. Secretory agents have high specificity, low bioavailability and high efficacy. The potential risks of agents 'borrowed' from other indications (such as hyperlipidaemia, inflammatory bowel disease or somatic pain) deserve further study.

CONCLUSIONS

There is reason for optimism in medical treatment of IBS with a spectrum of agents to treat bowel dysfunction. However, visceral analgesic treatments are still suboptimal.

Do the Symptom-Based, Rome Criteria of Irritable Bowel Syndrome Lead to Better Diagnosis and Treatment Outcomes? The Con Argument

Some claim that symptom-based Rome criteria are diagnostic and enhance clinical practice and choice of therapy for patients presenting with gastrointestinal symptoms. This overview focuses on lower gastrointestinal symptoms: constipation, diarrhea, pain and bloating. The main con arguments for using such criteria for diagnosis are: insufficient specificity, overlap of symptom-based categories or disorders, insufficient and therefore non-specific characterization of pain in the criteria, inability to differentiate the "mimics" of IBS-C and IBS-D, and inability to optimize treatment for IBS-M or bloating in the absence of objective measurements. While doctors may not land in trouble using "symptom diagnosis" of IBS, this should not deter them from optimizing diagnosis and treatment of diseases associated with gastrointestinal dysfunction.

Irritable bowel syndrome: towards biomarker identification

Irritable bowel syndrome (IBS), the most common functional gastrointestinal disorder referred to gastroenterologists, affects 7-10% of the general population worldwide. The lack of suitable disease-defining biological markers coupled with a poorly understood underlying pathophysiology complicates patient diagnosis and seriously hampers drug discovery efforts. Over the past few years, a number of potential biomarkers have emerged, and in this review we critically evaluate such candidates. In particular, we highlight the increasing number of studies supporting a low-grade immune activation in IBS and consider how the latest preclinical developments can contribute to the development of more robust and reliable biological markers of this disorder. The successful identification of biomarkers is critical to progressing our understanding of IBS and addressing the unmet therapeutic needs of this debilitating condition.