Effect of linaclotide on severe abdominal symptoms in patients with irritable bowel syndrome with constipation

The gut microbiota participates in the effect of linaclotide in patients with irritable bowel syndrome with constipation (IBS-C): a multicenter, prospective, pre-post study

BACKGROUND

Interindividual variation characterizes the relief experienced by constipation-predominant irritable bowel syndrome (IBS-C) patients following linaclotide treatment. Complex bidirectional interactions occur between the gut microbiota and various clinical drugs. To date, no established evidence has elucidated the interactions between the gut microbiota and linaclotide. We aimed to explore the impact of linaclotide on the gut microbiota and identify critical bacterial genera that might participate in linaclotide efficacy.

METHODS

IBS-C patients were administered a daily linaclotide dose of 290 µg over six weeks, and their symptoms were then recorded during a four-week posttreatment observational period. Pre- and posttreatment fecal samples were collected for 16S rRNA sequencing to assess alterations in the gut microbiota composition. Additionally, targeted metabolomics analysis was performed for the measurement of short-chain fatty acid (SCFA) concentrations.

RESULTS

Approximately 43.3% of patients met the FDA responder endpoint after taking linaclotide for 6 weeks, and 85% of patients reported some relief from abdominal pain and constipation. Linaclotide considerably modified the gut microbiome and SCFA metabolism. Notably, the higher efficacy of linaclotide was associated with enrichment of the Blautia genus, and the abundance of Blautia after linaclotide treatment was higher than that in healthy volunteers. Intriguingly, a positive correlation was found for the Blautia abundance and SCFA concentrations with improvements in clinical symptoms among IBS-C patients.

CONCLUSION

The gut microbiota, especially the genus Blautia, may serve as a significant predictive microbe for symptom relief in IBS-C patients receiving linaclotide treatment.

TRIAL REGISTRATION

This trial was registered with the Chinese Clinical Trial Registry (Chictr.org.cn, ChiCTR1900027934).

Approach to Disorders of Gut-Brain Interaction

Disorders of gut-brain interaction, previously known as functional gastrointestinal disorders (eg, functional dyspepsia and irritable bowel syndrome), are commonly encountered in both the primary care and gastroenterology clinics. These disorders are often associated with high morbidity and poor patient quality of life and often lead to increased health care use. The management of these disorders can be challenging, as patients often present after having undergone an extensive workup without a definite etiology. In this review, we provide a practical five-step approach to the clinical assessment and management of disorders of gut-brain interaction. The five-step approach includes (1) excluding organic etiologies of the patient's symptoms and using Rome IV criteria for diagnosis, (2) empathizing with the patient to develop trust and a therapeutic relationship, (3) educating the patient about the pathophysiology of these gastrointestinal disorders, (4) expectation setting with a focus on improving function and quality of life, and (5) establishing a treatment plan with central and peripherally acting medications and nonpharmacological modalities. We discuss the pathophysiology of disorders of gut-brain interaction (eg, visceral hypersensitivity), initial assessment and risk stratification, as well as treatment for a variety of diseases with a focus on irritable bowel syndrome and functional dyspepsia.

Update on treatment of abdominal pain in irritable bowel syndrome: A narrative review

The objectives of this narrative review are to update readers on the current state-of-the-art regarding diverse approaches for the treatment of pain, global symptoms, or adequate relief in irritable bowel syndrome (IBS). The article appraises medications, dietary interventions including low fermentable oligosaccharides, disaccharides, and monosaccharides and polyols (FODMAP) diet, fecal microbial transplantation (FMT), electrical approaches, and behavioral therapies including cognitive behavioral therapy (CBT), gut-directed hypnotherapy (GDH), mindfulness, and open-label placebo. Current evidence demonstrates only modest benefit in global IBS symptoms and pain relief. A future approach that identifies pathophysiological mechanisms of IBS through validated biomarkers has the potential to individualize treatment of patients rather than sequential therapeutic trial and error approaches.

Randomised clinical trial: effects of MD-7246 on irritable bowel syndrome with diarrhoea

BACKGROUND

MD-7246, a delayed-release formulation of linaclotide, is designed to target the ileocaecal junction and caecum with the aim of relieving abdominal pain independently of bowel function.

AIMS

To evaluate the efficacy, safety and dose-response of MD-7246 in patients with irritable bowel syndrome with diarrhoea (IBS-D).

METHODS

A randomised, double-blind, phase 2 clinical trial enrolled adult patients with IBS-D (Rome IV criteria). Patients were randomised to placebo or once-daily oral MD-7246 300, 600 or 1200 μg for 12 weeks. Abdominal and bowel symptoms were assessed daily. Key efficacy endpoints were change from baseline in abdominal pain and responder rates for a 30% reduction in abdominal pain in 6/12 weeks. Additional abdominal pain responder and exploratory bowel function endpoints were also assessed.

RESULTS

Among the 388 randomised patients, there was no significant difference in mean change from baseline in abdominal pain between the MD-7246 300 μg, 600 μg and 1200 μg groups and placebo (-1.93, -1.58, -1.95 and - 2.01, respectively; p > 0.05 for each group vs placebo). The abdominal pain responder rates in the MD-7246 groups were similar to or lower than those in the placebo group. All doses of MD-7246 had a minimal effect on bowel function and were generally well tolerated.

CONCLUSIONS

MD-7246 at the doses studied did not improve abdominal pain relative to placebo in an IBS-D patient population. Similarly, most additional efficacy endpoints showed no improvement with MD-7246 relative to placebo.

Linaclotide for treating patients with irritable bowel syndrome with predominant constipation: a multicentre study of real-world data in China

INTRODUCTION

Linaclotide, a guanylate cyclase C agonist that improves the symptoms of irritable bowel syndrome with predominant constipation (IBS-C), has been recently approved for IBS-C treatment. This study aimed to report real-world data on linaclotide treatment in China.

METHODS

This was a prospective multicentre study of the effectiveness of linaclotide treatment in patients with IBS-C from 10 primary medical institutions. Changes in defecation, abdominal symptoms, the IBS symptom severity scale (IBS-SSS), IBS quality of life questionnaire (IBS-QOL), Zung Self-Rating Anxiety Scale and Self-Rating Depression Scale in patients were evaluated to determine the drug's clinical efficacy and safety.

RESULTS

We enrolled 97 patients (mean age: 52.39 ± 13.99 years), 55 of whom were women (56.7%). In terms of efficacy, the number of the patients' defecation per week and Bristol stool form scale scores significantly increased at week 4 and week 12 compared with the values at the baseline. The baseline average IBS-SSS score was 211.01 ± 81.23. Of the patients, 24 had severe IBS-C, and their IBS-SSS scores at week 4 (51.81 ± 54.42) and week 12 (9.3 ± 30.39) significantly decreased and showed a pronounced improvement. The IBS-QOL total scores at week 4 and week 12 gradually decreased compared with that at the baseline and the QOL significantly improved. Treatment satisfaction rate was 79.3% in week 4 and 100% in week 12, showing a gradually increased satisfaction and significant differences. However, 11 cases (11.3%) had diarrhoea.

CONCLUSION

Linaclotide has proved to be a safe and effective drug to improve IBS-C symptoms and severity.

Review article: current and future treatment approaches for IBS with constipation

BACKGROUND

Multiple efficacious therapies are currently available for treating irritable bowel syndrome with constipation (IBS-C). IBS-C specific survey tools that assess symptom relief, treatment satisfaction, and quality of life are important for gauging real-world effectiveness.

AIMS/METHODS

This article reviews clinical trial efficacy data as well as survey data on adequate relief and quality of life from pivotal trials for lubiprostone, linaclotide, plecanatide, tenapanor, and tegaserod. A brief discussion of agents in development with novel mechanisms of action is also provided.

RESULTS/CONCLUSIONS

Quality of life and symptom metrics should be standardized and continue to be represented in future IBS-C trials. The choice of agent should be tailored to probability of improving symptoms, safety, tolerability, and cost.

Efficacy of Linaclotide in Reducing Abdominal Symptoms of Bloating, Discomfort, and Pain: A Phase 3B Trial Using a Novel Abdominal Scoring System

INTRODUCTION

Linaclotide improves abdominal pain and constipation in patients with constipation-predominant irritable bowel syndrome (IBS-C). Patients report additional bothersome abdominal symptoms of bloating and discomfort. The intention of this study was to evaluate linaclotide's efficacy in relieving IBS-C-related abdominal symptoms (bloating, discomfort, and pain) using a novel multi-item Abdominal Score (AS).

METHODS

Patients with IBS-C with abdominal pain ≥3 (0-10 scale) were randomized to linaclotide 290 μg or placebo daily for 12 weeks. The AS, derived from the Diary for IBS Symptoms-Constipation, is the average of abdominal bloating, discomfort, and pain at their worst (0 = none, 10 = worst possible). The primary end point was overall change from baseline (CFB) in AS. Secondary end points included CFB in 12-week AS evaluated using cumulative distribution function and 6-week/12-week AS responder (AS improvement ≥2 points for ≥6-week/12-week).

RESULTS

Overall, 614 patients (mean age 46.7 years; 81% female) were randomized. All prespecified end points showed significant benefit of linaclotide vs placebo. The mean overall CFB AS reduction for linaclotide was -1.9 vs -1.2 for placebo (P < 0.0001); the 6-week/12-week AS responder rate was 40.5% for linaclotide vs 23.4% for placebo (odds ratio = 2.2 [95% confidence interval, 1.55-3.12; P < 0.0001]). Diarrhea was the most common treatment-emergent adverse event (linaclotide = 4.6%, placebo = 1.6%).

DISCUSSION

Linaclotide significantly reduced multiple abdominal symptoms important to patients with IBS-C (bloating, discomfort, and pain) compared with placebo, as measured by a novel multi-item AS. The AS, derived from the Diary for IBS Symptoms-Constipation, should be considered for use in future IBS-C clinical studies to measure clinically meaningful improvements beyond traditional end points.

Systematic review and network meta-analysis: efficacy of licensed drugs for abdominal bloating in irritable bowel syndrome with constipation

BACKGROUND

Although bloating is a highly prevalent and troublesome symptom in irritable bowel syndrome with constipation (IBS-C), treatment is empirical with no specific guidelines for its management.

AIM

To conduct a pairwise and network meta-analysis, using a frequentist approach, of Food and Drug Administration-licensed drugs for IBS-C comparing their efficacy for abdominal bloating as a specific endpoint.

METHODS

We searched the medical literature through December 2020 to identify randomised controlled trials (RCTs) in IBS-C, with abdominal bloating reported as a dichotomous assessment. Efficacy of each drug was reported as a pooled relative risk (RR) with 95% confidence intervals (CIs) to summarise effect of each comparison tested. Treatments were ranked according to their P-score.

RESULTS

We identified 13 eligible RCTs, containing 10 091 patients. Linaclotide 290 µg o.d., lubiprostone 8 µg b.d., tenapanor 50 mg b.d. and tegaserod 6 mg b.d. were all superior to placebo for abdominal bloating in patients with IBS-C, in both pairwise and the network meta-analyses. Linaclotide demonstrated the greatest improvement in abdominal bloating in both pairwise and network meta-analysis (RR of failure to achieve an improvement in abdominal bloating = 0.78; 95% CI 0.74-0.83, number needed to treat = 7, P-score 0.97). Indirect comparison revealed no significant differences between individual drugs.

CONCLUSIONS

We found all licensed drugs for IBS-C to be superior to placebo for abdominal bloating. Linaclotide appeared to be the most efficacious at relieving abdominal bloating. Further research is needed to assess long-term efficacy of these agents and to better understand the precise mechanism of improving bloating.

Validity and Reliability of the Malay Versions of Bloating Severity (BSQ-M) and Quality of Life (BLQoL-M) Questionnaires

Abdominal bloating (AB) is a prevalent and bothersome symptom, but there are no specific measures for severity and quality of life (QoL) other than the Bloating Severity Questionnaire (BSQ) and Bloating Quality of Life (BLQoL). We aimed to translate the BSQ and BLQoL into the Malay language and to validate them using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) approaches. The 12-item BSQ has two components, seven-item severity in general (SevGen) and five-item severity in the past 24 h (Sev24), and BLQOL has five items. Translation to the Malay language (BSQ-M and BLQoL-M) was performed using standard forward and backward processes. EFA followed by CFA were performed in participants with AB due to functional bowel disorders, with the purpose of examining the validity and reliability of the questionnaires translated into Malay. After EFA with 152 participants, all the items of BSQ-M remained in the model. Total variance extracted was 53.26% for BSQ-M and 58.79% for BLQoL-M. The internal consistency based on Cronbach's alpha values was 0.52 for SevGen, 0.86 for Sev24, and 0.81 for BLQoL-M. After performing CFA with another 323 participants, the final measurement model for BSQ-M and BLQoL-M fit the data well in terms of several fit indices (BSQ-M: root mean square error of approximation (RMSEA) = 0.050, Comparative Fit Index (CFI) = 0.966, Tucker-Lewis Fit Index (TLI) = 0.956, and standardized root mean squared residual (SRMR) = 0.051; BLQoL-M: RMSEA = 0.071, CFI = 0.985, TLI = 0.962, SRMR = 0.021). The composite reliability for BSQ-M and BLQoL-M were satisfactory (SevGen = 0.83, Sev24 = 0.89, BLQoL = 0.80). The intraclass correlation (ICC) results showed excellent stability for BSQ-M and BLQoL-M, ranging from 0.74 to 0.93. The Malay language versions of BSQ-M and BLQoL-M are valid and reliable instruments for measuring the severity and QoL of AB for the Asian population with functional bowel disorders.

Efficacy and Safety of 5-HT4 Receptor Agonist Minesapride for Irritable Bowel Syndrome with Constipation in a Randomized Controlled Trial

BACKGROUND & AIMS

Treatment options for irritable bowel syndrome with constipation (IBS-C) are limited-new prokinetic drugs are needed. We evaluated the efficacy and safety of minesapride (DSP-6952), a partial agonist with high affinity for 5-HT4 receptors, in patients with IBS-C in Japan.

METHODS

We performed a double-blind phase 2 study of 171 patients with Rome III-defined IBS-C at 33 centers in Japan, from December 2012 through August 2013. Patients were randomly assigned to groups given minesapride (1, 4, 12, or 40 mg) or placebo once daily for 4 weeks. The primary outcome was efficacy, defined as improvement in the weekly frequency of complete spontaneous bowel movements (CSBMs), abdominal symptoms, and IBS-C symptoms (according to the Japanese version of the IBS severity index score). For evaluation of safety, adverse events (AEs) were recorded.

RESULTS

The least squares mean change from baseline in the weekly frequency of CSBMs was greater in all minesapride groups than in the placebo group at week 4 (40 mg vs placebo, P = .040). The abdominal symptoms score improved in minesapride 40 mg group. The overall IBS severity index score decreased from baseline to week 4 in all treatment groups-especially in the 12 mg and 40 mg groups (P = .048 and <.001 vs placebo, respectively). The proportions of patients with treatment-emergent AEs in the pooled minesapride and placebo groups were 55.0% and 60.0%, respectively. The most common treatment-emergent AE was diarrhea (in 42.9% and 37.1% of patients in the pooled minesapride and placebo groups, respectively).

CONCLUSIONS

In a phase 2 trial of patients with IBS-C in Japan, minesapride increased stool frequency (measured by CSBMs), reduced abdominal and overall IBS-C symptoms, and was well tolerated. Japan Pharmaceutical Information Center trial no: JapicCTI-122041.

Pharmacotherapy patterns in patients with chronic idiopathic constipation beginning treatment with linaclotide or lubiprostone in the United States

BACKGROUND

Chronic idiopathic constipation (CIC) is a common gastrointestinal disorder in community settings. Limited information exists on its treatment with the prosecretory agents linaclotide and lubiprostone. This retrospective cohort study investigated real-world pharmacotherapy patterns of linaclotide and lubiprostone.

METHODS

Patients (≥18 years) with CIC who received linaclotide or lubiprostone between January 2013 and December 2015 were identified in a United States health insurance claims database. Follow-up was from the date of the earliest claim for either drug to the end of continuous enrolment or switch to the alternative agent. Patterns of pharmacotherapy, evidence of irritable bowel syndrome (IBS), and concomitant use of selective serotonin reuptake inhibitors were examined using the International Classification of Diseases, Ninth or Tenth Revision, Clinical Modification codes and National Drug Codes.

RESULTS

In total, 43,164 and 17,743 patients with CIC received linaclotide and lubiprostone, respectively (~80% women, mean age ~47 years). Approximately 40% of subjects (linaclotide: 40.1%; lubiprostone: 37.6%) had evidence of IBS. Over a mean follow-up of 17 months, mean (standard deviation) treatment duration in patients without IBS was 6.6 (7.9) months for linaclotide and 4.5 (6.5) months for lubiprostone. Treatment episodes >180 days were more common with linaclotide (36.1%) than with lubiprostone (23.2%). At 12 months, Kaplan-Meier estimates of switching from lubiprostone to linaclotide and from linaclotide to lubiprostone were 13.4 and 5.6%, respectively. The number of patients receiving serotonin reuptake inhibitors was unchanged with treatment (~22%).

CONCLUSIONS

Most patients with CIC receive linaclotide or lubiprostone for <6 months; few remain on therapy for >1 year. Additional research is warranted to understand the potential reason(s) for early discontinuation.

Randomised clinical trial: linaclotide vs placebo-a study of bi-directional gut and brain axis

BACKGROUND

Linaclotide, a guanylate cyclase C agonist relieves irritable bowel syndrome with predominant constipation (IBS-C) symptoms, but how it improves pain in humans is unknown.

AIMS

To investigate the effects of linaclotide and placebo on the afferent and efferent gut-brain-gut signalling in IBS-C patients, in a randomised clinical trial.

METHODS

Patients with IBS-C (Rome III) and rectal hypersensitivity were randomised (2:1) to receive linaclotide (290 µg) or placebo for 10 weeks and undergo bi-directional gut and brain axis assessment using anorectal electrical stimulations and transcranial/transspinal-anorectal magnetic stimulations. Rectal sensations were examined by balloon distention. Assessments included abdominal pain, bowel symptoms and quality of life (QOL) scores. Primary outcomes were latencies of recto-cortical and cortico-rectal evoked potentials.

RESULTS

Thirty-nine patients participated; 26 received linaclotide and 13 received placebo. Rectal cortical evoked potentials latencies (milliseconds) were significantly prolonged with linaclotide compared to baseline (P1:Δ 19 ± 6, P < 0.005; N1:Δ 20 ± 7, P < 0.02) but not with placebo (P1:Δ 3 ± 5; N1:Δ 4.7 ± 5,P = 0.3) or between groups. The efferent cortico-anorectal and spino-anorectal latencies were unchanged. The maximum tolerable rectal volume (cc) increased significantly with linaclotide compared to baseline (P < 0.001) and placebo (Δ 29 ± 10 vs 4 ± 20, (P < 0.03). Abdominal pain decreased (P < 0.001) with linaclotide but not between groups. Complete spontaneous bowel movement frequency increased (P < 0.001), and IBS-QOL scores improved (P = 0.01) with linaclotide compared to baseline and placebo. There was no difference in overall responders between linaclotide and placebo (54% vs 23%, P = 0.13).

CONCLUSIONS

Linaclotide prolongs afferent gut-brain signalling from baseline but both afferent and efferent signalling were unaffected compared to placebo. Linaclotide significantly improves rectal hypersensitivity, IBS-C symptoms and QOL compared to placebo. These mechanisms may explain the effects of linaclotide on pain relief in IBS-C patients. ClinicalTrials.Gov: Registered at Clinical trials.gov no NCT02078323.

Efficacy and safety of linaclotide for opioid-induced constipation in patients with chronic noncancer pain syndromes from a phase 2 randomized study

Constipation is the most common adverse event (AE) of opioid therapy. This multicenter, phase 2 study evaluated the efficacy and safety of linaclotide in treating opioid-induced constipation (OIC) in patients with chronic noncancer pain syndromes (NCT02270983). Adults with OIC (<3 spontaneous bowel movements [SBMs]/week) related to chronic noncancer pain were randomized 1:1:1 to receive linaclotide 145 µg, linaclotide 290 µg, or placebo once daily for 8 weeks. The primary endpoint was change from baseline in 8-week SBM frequency rate (SBMs/week). Secondary efficacy endpoints included 6/8-week SBM 3 + 1 responders, time to first SBM, and changes from baseline in 8-week stool consistency, abdominal bloating, and straining. Additional endpoints included treatment satisfaction and adequate relief responders. In total, 254 patients were randomized: 87, 88, and 79 received linaclotide 145 µg, linaclotide 290 µg, and placebo, respectively. The mean changes from baseline in SBMs/week during the treatment period were 2.9 and 3.5 in the linaclotide 145 and 290 µg groups (P < 0.01 for both doses), respectively, vs 1.6 in the placebo group. Diarrhea, the most common AE, was generally mild, resulting in 1.1%, 5.7%, and 1.3% of patients discontinuing in the linaclotide 145 μg, linaclotide 290 μg, and placebo groups, respectively. No serious AEs related to diarrhea were reported in any treatment group. Compared with placebo, linaclotide-treated patients had significant improvements in stool consistency, straining, abdominal bloating, and treatment satisfaction scores (P < 0.05). Linaclotide significantly improved OIC symptoms and was well tolerated in patients with chronic noncancer pain.

A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation

Background/Aims

Magnesium oxide (MgO) has been frequently used as a treatment for chronic constipation (CC) since the 1980s in Japan. The aim of this study is to evaluate its therapeutic effects of MgO in Japanese CC patients.

Methods

We conducted a randomized, double-blind placebo-controlled study. Thirty-four female patients with mild to moderate constipation were randomly assigned to either placebo (n = 17) or MgO group (n = 17) 0.5 g × 3/day for 28 days. Primary endpoint was overall improvement over the 4-week study period. Secondary endpoints were changes from baseline in spontaneous bowel movement (SBM), response rates of complete spontaneous bowel movement (CSBM), stool form, colonic transit time (CTT), abdominal symptom, and quality of life.

Results

One patient failed to complete the medication regimen and was omitted from analysis: data from 16 placebo and 17 MgO patients were analyzed. The primary endpoint was met by 25.0% of placebo vs 70.6% of MgO group (P = 0.015). MgO significantly improved SBM changes compared to placebo (P = 0.002). However, MgO did not significantly improved response rates of CSBM compared to placebo (P = 0.76). In addition, MgO significantly improved Bristol stool form scale changes (P < 0.001) and significantly improved CTT compared to the placebo group (P < 0.001). MgO significantly improved the Japanese version of the patient assessment of constipation quality of life (P = 0.003).

Conclusion

Our placebo-controlled study demonstrated that MgO was effective treatment for improving defecation status and shortened CTT in Japanese CC patients with mild to moderate symptoms.

Clinical response to linaclotide at week 4 predicts sustained response in irritable bowel syndrome with constipation and improvements in digestive and extra-digestive symptoms

BACKGROUND

Linaclotide is approved for the treatment of moderate-to-severe irritable bowel syndrome (IBS) with constipation (IBS-C) in adults. This study aimed to assess factors predictive of a clinical response and improvements in non-IBS symptoms with linaclotide treatment in a Spanish patient population.

METHODS

In this open-label phase IIIb study, patients with moderate-to-severe IBS-C received linaclotide 290 μg once daily for 12 weeks. The primary endpoint was clinical response at week 12, defined as >30% reduction in IBS symptom severity score (IBS-SSS) or IBS-SSS <75 plus self-reported response of feeling 'better' or 'much better' versus the baseline. Digestive nonintestinal and extra-digestive symptom scores were assessed. Baseline characteristics and week 4 clinical response were assessed as predictors of week 12 clinical response.

RESULTS

A total of 96 patients were eligible; 91 were female and the mean age was 47.4 years. Mean (SD) baseline IBS-SSS was 371 (72.5). In the intention-to-treat and per-protocol populations, 22.9% and 31.7% were clinical responders at week 4, respectively, and 25.0% and 36.7% were clinical responders at week 12. Digestive nonintestinal and extra-digestive symptom scores were significantly improved at weeks 4 and 12. Baseline characteristic was not associated with week 12 clinical response; however, clinical response at week 4 was predictive of response at week 12 (OR: 6.5; 95%IC: 2.1-19.8). The most common adverse event was diarrhea inclusive of loose or watery stools (35.4%).

CONCLUSIONS

Linaclotide improves IBS-C symptoms, including digestive nonintestinal and extra-digestive symptoms. A clinical response at week 4 may predict response at week 12.

Engineering of an Anti-Inflammatory Peptide Based on the Disulfide-Rich Linaclotide Scaffold

Inflammatory bowel diseases are a set of complex and debilitating diseases, for which there is no satisfactory treatment. Peptides as small as three amino acids have been shown to have anti-inflammatory activity in mouse models of colitis, but they are likely to be unstable, limiting their development as drug leads. Here, we have grafted a tripeptide from the annexin A1 protein into linaclotide, a 14-amino-acid peptide with three disulfide bonds, which is currently in clinical use for patients with chronic constipation or irritable bowel syndrome. This engineered disulfide-rich peptide maintained the overall fold of the original synthetic guanylate cyclase C agonist peptide, and reduced inflammation in a mouse model of acute colitis. This is the first study to show that this disulfide-rich peptide can be used as a scaffold to confer a new bioactivity.

UK clinical experience up to 52 weeks with linaclotide for irritable bowel syndrome with constipation

BACKGROUND

Linaclotide, a guanylate cyclase C agonist, has been shown in clinical trials to improve symptoms of irritable bowel syndrome with constipation (IBS-C). Here we report data from a real-world study of linaclotide in the UK.

METHODS

This 1-year, multicentre, prospective, observational study in the UK enrolled patients aged 18 years and over initiating linaclotide for IBS-C. The primary assessment was change from baseline in IBS Symptom Severity Scale (IBS-SSS) score at 12 weeks, assessed in patients with paired baseline and 12-week data. Change from baseline in IBS-SSS score at 52 weeks was a secondary assessment. Adverse events were recorded.

RESULTS

In total, 202 patients were enrolled: 185 (91.6%) were female, median age was 44.9 years (range 18.1-77.2) and 84 (41.6%) reported baseline laxative use. Mean (standard deviation) baseline IBS-SSS score was 339 (92), with most patients (n = 129; 66.8%) classified as having severe disease (score ⩾300). In patients with paired data, there was a significant mean (95% confidence interval) decrease in IBS-SSS score from baseline to 12 weeks [-77.0 (-96.3, -57.7); p < 0.001; n = 124] and baseline to 52 weeks [-70.7 (-95.0, -46.5); p < 0.001; n = 76]. Overall, 174 adverse events were reported in 77 (38.1%) patients, most commonly diarrhoea (n = 54; 26.7%), abdominal pain (n = 21; 10.4%) and abdominal distension (n = 13; 6.4%).

CONCLUSION

Linaclotide significantly improved IBS-SSS score at 12 and 52 weeks. These results provide insights into outcomes with linaclotide treatment over 1 year in patients with IBS-C in real-world clinical practice.

Clinical utility of plecanatide in the treatment of chronic idiopathic constipation

Constipation is an important health burden that reduces the quality of life for countless millions of people. Symptom-centric therapeutics are often used to treat constipation due to unknown etiology, but in many cases, these drugs are either inadequate or have significant side effects. More recently, synthetic peptide agonists for epithelial guanylyl cyclase C (GC-C) have been developed which are effective at treating constipation in a sub-population of adult constipation patients. The first to market was linaclotide that is structurally related to the diarrheagenic enterotoxin, but this was followed by plecanatide, which more closely resembles endogenous uroguanylin. Both the drugs exhibit almost identical clinical efficacy in about 20% of patients, with diarrhea being a common side effect. Despite the potential for reduced side effects with plecanatide, detailed analysis suggests that clinically, they are very similar. Ongoing clinical and preclinical studies with these drugs suggest that treating constipation might be the tip of the iceberg in terms of clinical utility. The expression of cGMP signaling components could be diagnostic for functional bowel disorders, and increasing cGMP using GC-C agonists or phosphodiesterase inhibitors has huge potential for treating enteric pain, ulcerative colitis, and for the chemoprevention of colorectal cancer.

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.

[Bloating]

Bloating is one of the most common and troublesome problems in a large proportion of patients with gastrointestinal disorders but the mechanism is not completely understood. Several factors, including gas-producing intestinal microbiota, disturbed handling of intestinal gas, visceral hypersensitivity, abnormal viscero-somatic responses, fermentable diet, and psychological factors, have been suggested as mechanisms. For an assessment, thorough medical history-taking and physical examination are the first steps. On the other hand, organic disorders should always be considered first for a differential diagnosis. The therapeutic options available are considered challenging and still limited in clinical practice. The treatment strategy may include diet modification, pharmacologic approach, psychiatric approach, biofeedback, etc. Further studies will be needed to explore the variable mechanism of bloating and develop an efficient treatment.

New therapeutic perspectives in irritable bowel syndrome: Targeting low-grade inflammation, immuno-neuroendocrine axis, motility, secretion and beyond

Irritable bowel syndrome (IBS) is a chronic, recurring, and remitting functional disorder of the gastrointestinal tract characterized by abdominal pain, distention, and changes in bowel habits. Although there are several drugs for IBS, effective and approved treatments for one or more of the symptoms for various IBS subtypes are needed. Improved understanding of pathophysiological mechanisms such as the role of impaired bile acid metabolism, neurohormonal regulation, immune dysfunction, the epithelial barrier and the secretory properties of the gut has led to advancements in the treatment of IBS. With regards to therapies for restoring intestinal permeability, multiple studies with prebiotics and probiotics are ongoing, even if to date their efficacy has been limited. In parallel, much progress has been made in targeting low-grade inflammation, especially through the introduction of drugs such as mesalazine and rifaximin, even if a better knowledge of the mechanisms underlying the low-grade inflammation in IBS may allow the design of clinical trials that test the efficacy and safety of such drugs. This literature review aims to summarize the findings related to new and investigational therapeutic agents for IBS, most recently developed in preclinical as well as Phase 1 and Phase 2 clinical studies.

Bloating and Abdominal Distension: Old Misconceptions and Current Knowledge

Bloating, as a symptom and abdominal distension, as a sign, are both common functional-type complaints and challenging to manage effectively. Individual patients may weight differently the impact of bloating and distension on their well-being. Complaints may range from chronic highly distressing pain to simply annoying and unfashionable protrusion of the abdomen. To avoid mishaps, organic bloating, and distension should always be considered first and appropriated assessed. Functional bloating and distension often present in association with other manifestations of irritable bowel syndrome or functional dyspepsia and in that context patients tend to regard them as most troublesome. A mechanism-based management bloating and distension should be ideal but elucidating key operational mechanisms in individual patients is not always feasible. Some clues may be gathered through a detailed dietary history, by assessing bowel movement frequency and stool consistency and special imaging technique to measure abdominal shape during episodes of distension. In severe, protracted cases it may be appropriate to refer the patient to a specialized center where motility, visceral sensitivity, and abdominal muscle activity in response to intraluminal stimuli may be measured. Therapeutic resources focussed upon presumed or demonstrated pathogenetic mechanism include dietary modification, microbiome modulation, promoting gas evacuation, attenuating visceral perception, and controlling abdominal wall muscle activity via biofeedback.

Luminally Acting Agents for Constipation Treatment: A Review Based on Literatures and Patents

Constipation is one of the most frequently reported gastrointestinal (GI) disorders that negatively impacts quality of life and is associated with a significant economic burden to the patients and society. Traditional treatments including lifestyle modification and laxatives are often ineffective in the more severe forms of constipation and over the long term. New medications targeting at intestinal chloride channels and colonic serotonin receptors have been demonstrated effective in recent years. Emerging agents focusing on improving intestinal secretion and/or colonic motility have been shown effective in animal models and even in clinical trials. Recognization of the role of cystic fibrosis transmembrane regulator (CFTR) and calcium-activated chloride channels (CaCCs) in intestine fluid secretion and motility modulation makes CFTR and CaCCs promising molecule targets for anti-constipation therapy. Although there are multiple choices for constipation treatment, there is still a recognized need for new medications in anti-constipation therapy. The present review covers the discovery of luminally acting agents for constipation treatment described in both patents (2011–present) and scientific literatures.

Dietary and pharmacological treatment of abdominal pain in IBS

This review introduces the principles of visceral sensation and appraises the current approaches to management of visceral pain in functional GI diseases, principally IBS. These approaches include dietary measures including fibre supplementation, low fermentable oligosaccharides, disaccharides, monosaccharides and polyols diet, and pharmacological approaches such as antispasmodics, peppermint oil, antidepressants (tricyclic agents, selective serotonin reuptake inhibitors), 5-HT₃ receptor antagonists (alosetron, ondansetron, ramosetron), non-absorbed antibiotic (rifaximin), secretagogues (lubiprostone, linaclotide), μ-opioid receptor (OR) and κ-OR agonist, δ-OR antagonist (eluxadoline), histamine H1 receptor antagonist (ebastine), neurokinin-2 receptor antagonist (ibodutant) and GABAergic agents (gabapentin and pregabalin). Efficacy and safety are discussed based on pivotal trials or published systematic reviews and meta-analysis, expressing ORs or relative risks and their 95% CIs. Potential new approaches may be based on recent insights on mucosal expression of genes, and microRNA and epigenetic markers in human biopsies and in animal models of visceral hypersensitivity.The objectives of this review are to appraise the physiology and anatomy of gut sensation and the efficacy in the relief of visceral pain (typically in IBS) of several classes of therapies. These include fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) and different classes of medications (box 1). Box 1Classes of pharmacological agents for visceral painAntidepressants (tricyclic agents, selective serotonin reuptake inhibitors)Peppermint oil5-HT₃ receptor antagonists (alosetron, ondansetron, ramosetron)Non-absorbed antibiotic (rifaximin)Secretagogues (lubiprostone, linaclotide)μ-Opioid receptor (OR) and κ-OR agonist and δ-OR antagonist (eluxadoline)Histamine H1 receptor antagonist (ebastine)Neurokinin-2 receptor antagonist (ibodutant)GABAergic agents (gabapentin and pregabalin).

Electroacupuncture for Functional Constipation: A Multicenter, Randomized, Control Trial

Background and Aim. To investigate the efficacy and safety of electroacupuncture (EA) with different current intensities for functional constipation (FC) and to assess whether the effects of EA with different current intensities are superior to the mosapride. Methods. Patients with FC were randomly divided into low current intensity group (LCI), high current intensity group (HCI), and mosapride group (MC). The primary outcome was three or more spontaneous bowel movements (SBMs) per week and an increase of one or more SBMs from baseline during at least 3 of the 4 weeks. Results. The primary outcome was reached by 53.45%, 66.15%, and 52.24% of the patients who received LCI, HCI, and mosapride, respectively. EA can significantly improve the weekly SBMs and stool consistency and reduce straining severity (p < 0.0001, all). HCI improved the quality of life better than mosapride (p < 0.05) and reduced the proportion of severe constipation more than LCI and mosapride (p < 0.05, both). Conclusions. EA is effective and safe at both current intensities for FC; therapeutic effects of LCI and HCI are not superior to mosapride. EA is superior to mosapride in improving patients' life quality and satisfaction level of treatment; EA has fewer adverse events than mosapride.

Common Functional Gastroenterological Disorders Associated With Abdominal Pain

Although abdominal pain is a symptom of several structural gastrointestinal disorders (eg, peptic ulcer disease), this comprehensive review will focus on the 4 most common nonstructural, or functional, disorders associated with abdominal pain: functional dyspepsia, constipation-predominant and diarrhea-predominant irritable bowel syndrome, and functional abdominal pain syndrome. Together, these conditions affect approximately 1 in 4 people in the United States. They are associated with comorbid conditions (eg, fibromyalgia and depression), impaired quality of life, and increased health care utilization. Symptoms are explained by disordered gastrointestinal motility and sensation, which are implicated in various peripheral (eg, postinfectious inflammation and luminal irritants) and/or central (eg, stress and anxiety) factors. These disorders are defined and can generally be diagnosed by symptoms alone. Often prompted by alarm features, selected testing is useful to exclude structural disease. Identifying the specific diagnosis (eg, differentiating between functional abdominal pain and irritable bowel syndrome) and establishing an effective patient-physician relationship are the cornerstones of therapy. Many patients with mild symptoms can be effectively managed with limited tests, sensible dietary modifications, and over-the-counter medications tailored to symptoms. If these measures are not sufficient, pharmacotherapy should be considered for bowel symptoms (constipation or diarrhea) and/or abdominal pain; opioids should not be used. Behavioral and psychological approaches (eg, cognitive behavioral therapy) can be helpful, particularly in patients with chronic abdominal pain who require a multidisciplinary pain management program without opioids.

Novel pharmacological therapies for irritable bowel syndrome

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder, which represents a major cost to healthcare services. Current pharmacological treatment includes fibre supplements, antispasmodics, laxatives, loperamide and antidepressants. This article reviews the novel pharmacological treatments already or recently approved for patients with IBS-C (lubiprostone, linaclotide) and IBS-D (alosetron, ramosetron, rifaximin, eluxadoline). Furthermore, results for drugs in development (plecanatide, ibudutant and ebastine) or used in chronic constipation or for other indications, with potential application in IBS (prucalopride, elobixibat, mesalazine, ondansetron and colesevelam) are also reviewed.

New and emerging therapies for the treatment of irritable bowel syndrome: an update for gastroenterologists

Irritable bowel syndrome is a functional bowel disorder with gastrointestinal symptoms (e.g. abdominal pain, straining, urgency, incomplete evacuation, nausea, and bloating) that occur alongside bowel function alterations (i.e. constipation, diarrhea, or both). Patients with irritable bowel syndrome may also experience comorbid anxiety and depression. Irritable bowel syndrome is common, with a prevalence estimated between 3% and 28%, affecting patient health and quality of life. Patients with moderate or severe irritable bowel syndrome generally seek medical care, whereas those with milder symptoms may choose self-management. Most patients with irritable bowel syndrome receive outpatient care, but irritable bowel syndrome-related hospitalizations do occur. The pathophysiology of irritable bowel syndrome is multifactorial (i.e. genetics, immune components, changes in the gut microbiota, disturbances in physiologic stress response systems, and psychosocial factors). Management of irritable bowel syndrome can include lifestyle changes, dietary interventions, counseling, psychologic medication, and agents that affect gastrointestinal motility. A number of therapies have emerged in recent years with clinical trial data demonstrating efficacy and safety for patients with irritable bowel syndrome, including agents that target gastrointestinal motility (i.e. linaclotide), gastrointestinal opioid receptors (i.e. asimadoline, eluxadoline), and gut microbiota (i.e. rifaximin). Linaclotide has been shown to significantly improve stool frequency and abdominal pain compared with placebo in constipation-predominant irritable bowel syndrome (number needed to treat, 5.1). Asimadoline shows efficacy in patients with moderate-to-severe irritable bowel syndrome-related pain. Rifaximin provided adequate relief of global irritable bowel syndrome symptoms versus placebo for a significantly greater percentage of patients with diarrhea-predominant irritable bowel syndrome (p < 0.001). Management that encompasses all aspects of irritable bowel syndrome (gastrointestinal symptoms) and comorbid psychologic symptoms (e.g. anxiety or depression) is important for improving overall patient health and well-being.

New and Investigational Agents for Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) affects about 15 % of the US population and results in significant morbidity and health care costs. There remains a significant unmet need for effective treatments particularly for the pain component of IBS and other functional gastrointestinal disorders (FGIDs). Progress made in our understanding of pathophysiological mechanisms such as the role of altered bile acid metabolism, neurohormonal regulation, immune dysfunction, the epithelial barrier and secretory properties of the gut has led to advancements in therapeutic armamentarium for IBS. This review discusses the new drugs for constipation and diarrhea-predominant IBS subtypes that have been tested or have been under investigation over the last 3-4 years. Overall, there is a promising pipeline of investigational drugs for the future treatment of IBS and related FGIDs.

Chronic constipation in the elderly: a primer for the gastroenterologist

Constipation is a frequently reported bowel symptom in the elderly with considerable impact on quality of life and health expenses. Disease-related morbidity and even mortality have been reported in the affected frail elderly. Although constipation is not a physiologic consequence of normal aging, decreased mobility, medications, underlying diseases, and rectal sensory-motor dysfunction may all contribute to its increased prevalence in older adults. In the elderly there is usually more than one etiologic mechanism, requiring a multifactorial treatment approach. The majority of patients would respond to diet and lifestyle modifications reinforced by bowel training measures. In those not responding to conservative treatment, the approach needs to be tailored addressing all comorbid conditions. In the adult population, the management of constipation continues to evolve as well as the understanding of its complex etiology. However, the constipated elderly have been left behind while gastroenterology consultations for this common conditions are at a rise for the worldwide age increment. Aim of this review is to provide an update on epidemiology, quality of life burden, etiology, diagnosis, current approaches and limitations in the management of constipation in the older ones to ease the gastroenterologists’ clinic workload.

MRP4 Modulation of the Guanylate Cyclase-C/cGMP Pathway: Effects on Linaclotide-Induced Electrolyte Secretion and cGMP Efflux

MRP4 mediates the efflux of cGMP and cAMP and acts as an important regulator of these secondary messengers, thereby affecting signaling events mediated by cGMP and cAMP. Immunofluorescence staining showed high MRP4 expression localized predominantly in the apical membrane of rat colonic epithelium. In vitro studies were performed using a rat colonic mucosal layer mounted in an Ussing chamber. Linaclotide activation of the guanylate cyclase-C (GC-C)/cGMP pathway induced a concentration-dependent increase in transepithelial ion current [short-circuit current (Isc)] across rat colonic mucosa (EC50: 9.2 nM). Pretreatment of colonic mucosa with the specific MRP4 inhibitor MK571 potentiated linaclotide-induced electrolyte secretion and augmented linaclotide-stimulated intracellular cGMP accumulation. Notably, pretreatment with the phosphodiesterase 5 inhibitor sildenafil increased basal Isc, but had no amplifying effect on linaclotide-induced Isc. MRP4 inhibition selectively affected the activation phase, but not the deactivation phase, of linaclotide. In contrast, incubation with a GC-C/Fc chimera binding to linaclotide abrogated linaclotide-induced Isc, returning to baseline. Furthermore, linaclotide activation of GC-C induced cGMP secretion from the apical and basolateral membranes of colonic epithelium. MRP4 inhibition blocked cGMP efflux from the apical membrane, but not the basolateral membrane. These data reveal a novel, previously unrecognized mechanism that functionally couples GC-C-induced luminal electrolyte transport and cGMP secretion to spatially restricted, compartmentalized regulation by MRP4 at the apical membrane of intestinal epithelium. These findings have important implications for gastrointestinal disorders with symptoms associated with dysregulated fluid homeostasis, such as irritable bowel syndrome with constipation, chronic idiopathic constipation, and secretory diarrhea.

A randomized trial of 5-hydroxytryptamine4-receptor agonist, YKP10811, on colonic transit and bowel function in functional constipation

BACKGROUND & AIMS

YKP10811, a selective agonist of the serotonin 5-hydroxytryptamine-4 receptor, increases gastrointestinal (GI) motility. We investigated the safety and effects of YKP10811 on GI and colonic transit and bowel movements (BMs) in patients with functional constipation in a randomized, double-blind, placebo-controlled study.

METHODS

Patients with functional constipation, based on the Rome III criteria, were assigned randomly to groups given YKP10811 10 mg (n = 15), 20 mg (n = 16), 30 mg (n = 15), or placebo (n = 11) daily for 8 days. Transit of solids was measured by validated scintigraphy at baseline and on days 7 to 9. Patients kept diaries on days 1 to 9, recording time to first BM, number of BMs/day, and stool consistency (based on the Bristol Stool Form Scale). To evaluate safety, we collected data on adverse events and clinical laboratory test and electrocardiograms results. The primary efficacy end points were determined from an intent-to-treat analysis assessing colonic transit at 24 hours and the half-time (t1/2) of gastric emptying, using analysis of covariance models. Secondary efficacy end points included measures of colonic transit (geometric center at 4 and 24 hours), small-bowel transit (based on colon filling at 6 hours), t1/2 of ascending colon emptying, and bowel functions. We used the Dunnett test to compare the effects of each dose with placebo. A per-protocol analysis (PPA) assessed the t1/2 of gastric emptying and time to first BM using proportional hazards models.

RESULTS

Fifty-five participants completed the study. YKP10811 was associated with a significant acceleration in colon filling at 6 hours (P < .05), t1/2 of ascending colon emptying, and colonic transit at 24 and 48 hours, as well as increased stool consistency over 8 days (based on intent-to-treat analysis). In general, the 10-mg and 20-mg doses were the most effective in accelerating colonic transit. No serious adverse events were observed.

CONCLUSIONS

YKP10811, a selective agonist of the serotonin receptor 5-hydroxytryptamine-4, accelerates GI and colonic transit and improves bowel functions in patients with functional constipation, compared with placebo. ClinicalTrial.Gov: NCT01523184.

Advances in the management of constipation-predominant irritable bowel syndrome: the role of linaclotide

Constipation-predominant irritable bowel syndrome (IBS-C) is a commonly prevalent and clinically challenging disorder to treat. Until recently, most therapeutic agents had limited ability to address the complexity of symptoms inherent to the syndrome. The development of linaclotide provides a physiologically sound approach to treatment of the multiple symptoms of IBS-C. Clinical trials demonstrate the efficacy of linaclotide, and a platform to better understand the symptomatology of IBS-C. Based on recent clinical evidence, linaclotide should be considered for patients with IBS-C because it improves abdominal pain and bowel symptoms. In phase III trials, linaclotide met the US Food and Drug Administration responder endpoint with a number needed to treat (NNT) of 5.1-7.9, and European Medicines Agency coprimary endpoints at 12 weeks with a NNT of 4.39-7.69, and at 26 weeks with a NNT of 4.93-5.68. It is safe and effective, with diarrhea reported as the most common adverse effect, which leads to discontinuation of the medication in approximately 5% of patients.

Treatment of abdominal pain in irritable bowel syndrome

Functional abdominal pain in the context of irritable bowel syndrome (IBS) is a challenging problem for primary care physicians, gastroenterologists and pain specialists. We review the evidence for the current and future non-pharmacological and pharmacological treatment options targeting the central nervous system and the gastrointestinal tract. Cognitive interventions such as cognitive behavioral therapy and hypnotherapy have demonstrated excellent results in IBS patients, but the limited availability and labor-intensive nature limit their routine use in daily practice. In patients who are refractory to first-line therapy, tricyclic antidepressants (TCA) and selective serotonin reuptake inhibitors are both effective to obtain symptomatic relief, but only TCAs have been shown to improve abdominal pain in meta-analyses. A diet low in fermentable carbohydrates and polyols (FODMAP) seems effective in subgroups of patients to reduce abdominal pain, bloating, and to improve the stool pattern. The evidence for fiber is limited and only isphagula may be somewhat beneficial. The efficacy of probiotics is difficult to interpret since several strains in different quantities have been used across studies. Antispasmodics, including peppermint oil, are still considered the first-line treatment for abdominal pain in IBS. Second-line therapies for diarrhea-predominant IBS include the non-absorbable antibiotic rifaximin and the 5HT3 antagonists alosetron and ramosetron, although the use of the former is restricted because of the rare risk of ischemic colitis. In laxative-resistant, constipation-predominant IBS, the chloride-secretion stimulating drugs lubiprostone and linaclotide, a guanylate cyclase C agonist that also has direct analgesic effects, reduce abdominal pain and improve the stool pattern.