Effects of the 5-HT3 antagonist cilansetron vs placebo on phasic sigmoid colonic motility in healthy man: a double-blind crossover trial

Treatment of irritable bowel syndrome with diarrhoea using titrated ondansetron (TRITON): study protocol for a randomised controlled trial

BACKGROUND

Irritable bowel syndrome with diarrhoea (IBS-D) affects up to 4% of the general population. Symptoms include frequent, loose, or watery stools with associated urgency, resulting in marked reduction of quality of life and loss of work productivity. Ondansetron, a 5HT3 receptor antagonist, has had an excellent safety record for over 20 years as an antiemetic, yet is not widely used in the treatment of IBS-D. It has, however, been shown to slow colonic transit and in a small randomised, placebo-controlled, cross-over pilot study, benefited patients with IBS-D.

METHODS

This trial is a phase III, parallel group, randomised, double-blind, multi-centre, placebo-controlled trial, with embedded mechanistic studies. Participants (n = 400) meeting Rome IV criteria for IBS-D will be recruited from outpatient and primary care clinics and by social media to receive either ondansetron (dose titrated up to 24 mg daily) or placebo for 12 weeks. Throughout the trial, participants will record their worst abdominal pain, worst urgency, stool frequency, and stool consistency on a daily basis. The primary endpoint is the proportion of "responders" in each group, using Food and Drug Administration (FDA) recommendations. Secondary endpoints include pain intensity, stool consistency, frequency, and urgency. Mood and quality of life will also be assessed. Mechanistic assessments will include whole gut transit, faecal tryptase and faecal bile acid concentrations at baseline and between weeks 8 and 11. A subgroup of participants will also undergo assessment of sensitivity (n = 80) using the barostat, and/or high-resolution colonic manometry (n = 40) to assess motor patterns in the left colon and the impact of ondansetron.

DISCUSSION

The TRITON trial aims to assess the effect of ondansetron across multiple centres. By defining ondansetron's mechanisms of action we hope to better identify patients with IBS-D who are likely to respond.

TRIAL REGISTRATION

ISRCTN, ISRCTN17508514 , Registered on 2 October 2017.

Effects of 5-hydroxytryptamine (serotonin) type 3 antagonists on symptom relief and constipation in nonconstipated irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

We performed a systematic review and meta-analyses to estimate treatment efficacy and constipation rate of 5-hydroxytryptamine (serotonin) (5-HT(3)) antagonists in patients with nonconstipated (NC) or diarrhea-predominant (D)-irritable bowel syndrome (IBS).

METHODS

Two reviewers independently searched MEDLINE, EMBASE, and Web of Science (January 1, 1966 to December 15, 2006) for randomized controlled trials of 5-HT(3) antagonists in IBS reporting clinical end points of the IBS symptom complex and safety parameters. Study characteristics, markers of methodologic quality, and outcomes for the intention-to-treat population for each randomized controlled trial were extracted independently.

RESULTS

We found 14 eligible randomized controlled trials of alosetron (n = 3024) or cilansetron (n = 1116) versus placebo (n = 3043) or mebeverine (n = 304). Random-effects meta-analyses found 5-HT(3) antagonists more effective than the comparators in achieving global improvement in IBS symptoms (pooled relative risk, 1.60; 95% confidence interval [CI], 1.49-1.72; I(2) = 0%) and relief of abdominal pain and discomfort (pooled relative risk, 1.30; 95% CI, 1.22-1.39; I(2) = 22%). Benefit was apparent for both agents, in patients of either sex. These agents were more likely to cause constipation (pooled relative risk, 4.28; 95% CI, 3.28-5.60, I(2) = 65%); there was less constipation with 5-HT(3) antagonists in D-IBS patients than in mixed populations (NC-IBS and D-IBS; relative risk ratio, 0.65; 95% CI, 0.41-0.99). Nine patients (0.2%) using 5-HT(3) antagonists had possible ischemic colitis versus none in control groups.

CONCLUSIONS

5-HT(3) antagonists significantly improve symptoms of NC-IBS or D-IBS in men and women. There is an increased risk of constipation with 5-HT(3) antagonists, although the risk is lower in those with D-IBS.

Serotonin pharmacology in the gastrointestinal tract: a review

Serotonin (5-hydroxytryptamine or 5-HT) plays a critical physiological role in the regulation of gastrointestinal (GI) function. 5-HT dysfunction may also be involved in the pathophysiology of a number of functional GI disorders, such as chronic constipation, irritable bowel syndrome and functional dyspepsia. This article describes the role of 5-HT in the enteric nervous system (ENS) of the mammalian GI tract and the receptors with which it interacts. Existing serotonergic therapies that have proven effective in the treatment of GI functional disorders and the potential of drugs currently in development are also highlighted. Advances in our understanding of the physiological and pathophysiological roles of 5-HT in the ENS and the identification of selective receptor ligands bodes well for the future development of more efficacious therapies for patients with functional GI disorders.

Cilansetron in the treatment of diarrhea-predominant irritable bowel syndrome?

Information on the 5-hydroxytryptamine type 3 receptor antagonist cilansetron is scarce and most studies have only been published in abstract form. Results from preclinical and two dose-finding studies have suggested that cilansetron could be effective in the treatment of patients with diarrhea-predominant irritable bowel syndrome. Two large efficacy and safety trials extending over 3 and 6 months revealed a superiority of cilansetron 2 mg orally three-times daily over placebo reflected by numbers needed to treat of 4.8 and 5.6, respectively, for the parameter proportion of patients reporting adequate symptom relief. Dose-ranging studies showed no dose-response relationship. Cilansetron tended to induce constipation but, apart from transient ischemic colitis in four out of 1484 cases, no serious adverse effects were observed. Further trials are underway to fully determine the role of cilansetron in the treatment of diarrhea-predominant irritable bowel syndrome.

Cilansetron: A New Selective Serotonin Type 3 (5-HT3)-Receptor Antagonist for the Treatment of Irritable Bowel Syndrome in Males and Females

Irritable Bowel Syndrome (IBS) is a significant problem that affects a large proportion of the US population. The past several years have seen advances in our understanding of the pathophysiology associated with IBS and the development of new therapies. Older therapies have few well-designed clinical studies to support their use. The older studies tended to evaluate the impact of therapy on only one symptom and were ineffective at improving the overall symptomology in this functional disorder. In addition, the older drugs tended to produce side effects that often led to discontinuation of the therapy. Newer therapies, such as the FDA approved serotonergic agents (eg, alosetron and tegaserod), target abnormalities in gut physiology seen in IBS and not just the symptomatic presentation of the disease. In women, these medications have shown to be effective treatments for IBS with diarrhea (IBS-D) and IBS with constipation (IBS-C). Pending FDA approval, cilansetron represents the second 5-HT3 antagonist for the treatment of IBS-D. It has shown promising results in both men and women, which is an improvement over alosetron, since it is only approved for use in females. Similar to alosetron, the most common side effect seen with cilansetron therapy is constipation. Few cases of ischemic colitis, like those seen during alosetron therapy, have been reported in the cilansetron clinical trials and all have resolved without complication. A thorough review of the available data regarding cilansetron will be discussed in this article.

Cilansetron: a new serotonergic agent for the irritable bowel syndrome with diarrhoea

Cilansetron is a novel serotonin type-3 (5-hydroxytryptamine; 5-HT) receptor subtype 3 (5-HT(3)) receptor antagonist currently being evaluated for the treatment of female and male patients with irritable bowel syndrome with diarrhoea predominance (IBS-D). 5-HT(3) receptor antagonists such as cilansetron have been shown to affect gastrointestinal motility. Whether cilansetron affects visceral sensation independent of effects on visceral compliance remains controversial. Results from two large, randomised, double-blind, placebo-controlled, parallel-group Phase III clinical trials of cilansetron in patients with IBS-D have recently been presented in abstract form. These studies found that cilansetron was more effective than placebo at improving overall, as well as individual symptoms, including abdominal pain and diarrhoea in female and male IBS-D patients. The most commonly reported side effect with cilansetron has been constipation and, in general, the drug has been well tolerated in clinical trials. Although rare, the most concerning side effect observed with cilansetron has been suspected ischaemic colitis. The event rate for suspected ischaemic colitis associated with cilansetron from clinical trials is 3.77 per 1000 person years of exposure. This rate appears to be greater than that expected in the IBS population and similar to that observed with alosetron, another 5--HT(3) receptor antagonist. All of the cases of suspected ischaemic colitis reported with cilansetron have resolved without serious sequelae. How issues surrounding the safety of cilansetron will affect the approval process in various countries remains to be determined. However, the risk-benefit of cilansetron is likely to be most favourable in patients with IBS-D who have failed to respond to conventional medical therapies. A detailed risk management plan and post-marketing surveillance programme will be required should this drug become available for the treatment of patients with IBS-D.

Cilansetron: KC 9946

Cilansetron [KC 9946] is a serotonin-3 receptor (5-HT(3)) antagonist under development with Solvay Pharmaceuticals for the treatment of irritable bowel syndrome with diarrhoea predominance (IBS-D), in both men and women.5-HT(3) antagonists inhibit the 5-HT(3) receptors, resulting in decreased GI motility, secretion and sensation, thereby improving symptoms of IBS-D. Current 5-HT(3) therapy indicated for IBS-D is approved for women only.IBS is one of the most common functional gastrointestinal disorders, affecting an estimated 10-20% of the population in developed countries. Approximately twice as many women as men are diagnosed with IBS; however, this discrepancy may be due to more women seeking medical care. IBS is a chronic and bothersome disorder, and its symptoms, although not life-threatening, have a negative impact on quality of life (QOL), interfering with social activities, relationships and work. The degree to which IBS reduces quality of life appears to be directly related to symptom severity and intensity. In July 2001, Solvay signed an agreement with Quintiles (CRO) in order to optimise clinical research for cilansetron. In April 2004, Solvay Pharmaceuticals submitted a new drug application (NDA) for cilansetron in the UK (for the European Union) for the treatment of irritable bowel syndrome with diarrhoea predominance, in both men and women. In April 2005, Solvay Pharmaceuticals received a 'not-approvable' action letter from the US FDA on its NDA for cilansetron for the treatment of irritable bowel syndrome with diarrhoea predominance (IBS-D), in both men and women. The letter requested additional clinical trials, and Solvay is currently examining its options and will discuss future steps with the FDA. Solvay submitted the NDA for cilansetron in the US in June 2004 and included an extensive Appropriate Use Plan as part of its submission. The NDA submission was based on efficacy and safety studies in around 4000 patients worldwide with IBS-D. The FDA accepted for filing and granted priority review status for this NDA application in September 2004. According to Solvay's first half 2004 results, cilansetron is due to begin phase II clinical trials in Japan for the treatment of irritable bowel syndrome with diarrhoea predominance.

Bowel habit subtypes and temporal patterns in irritable bowel syndrome: systematic review

Irritable bowel syndrome (IBS) is a heterogeneous condition characterized by the presence of abdominal discomfort or pain and bowel habit alterations: constipation (C-IBS), diarrhea (D-IBS), or alternating C and D (A-IBS). Its clinical course is poorly known.

OBJECTIVES

(i) To compare bowel habit subtypes distribution in IBS according to sample origin and diagnosis criteria; (ii) To evaluate IBS temporal patterns based on follow-up studies.

METHODS

A literature search (1966-2003) was conducted in the MEDLINE and EMBASE databases. A total of 72 studies were found and 22 were finally selected.

RESULTS

Population-based studies from the United States (Manning) found similar distribution among C-IBS, D-IBS, and A-IBS, while European studies (Rome I, Rome II, or self-reporting) showed either C-IBS or A-IBS as the most prevalent subtypes. Primary care office-based studies (Rome I or Rome II) showed A-IBS as the most prevalent group. Gastroenterology specialized office-based studies found either C-IBS or D-IBS as the most frequently reported subtype. Prospective follow-up investigations showed that the most frequent IBS temporal pattern profile consists of mild to moderate symptoms appearing in cluster in an intermittent way, about once a week, and lasting 2-5 days on average.

CONCLUSION

IBS clinical subtypes distribution differs depending on the population evaluated, the geographical location, and the criteria employed to define IBS and bowel habit subtypes. In most cases, clinical course is characterized by the presence of mild-to-moderate symptoms appearing sequentially. Prospective studies, using clear and stable diagnostic criteria and subtype definitions, and based on daily data collection should further characterize IBS clinical course.

Meta-analysis: The treatment of irritable bowel syndrome

To evaluate therapies available for the treatment of irritable bowel syndrome, and provide consensus recommendations for their use, a total of 51 double-blind clinical trials using bulking agents, prokinetics, antispasmodics, alosetron, tegaserod and antidepressants were selected. The quality of studies was assessed using 5-point scale. Meta-analyses were performed on all studies, and on 'high-quality studies'. The efficacy of fibre in the global irritable bowel syndrome symptoms relief (OR: 1.9; 95% CI:1.5-2.4) was lost after exclusion of low-quality trials (OR: 1.4; 95% CI: 1.0-2.0, P = 0.06). When excluding the low-quality trials, an improvement of global irritable bowel syndrome symptoms with all antispasmodics (OR: 2.1; 95% CI:1.8-2.9) was maintained only for octylonium bromide, but on the basis of only two studies. Antidepressants were effective (OR: 2.6, 95% CI: 1.9-3.5), even after exclusion of low-quality studies (OR: 1.9, 95% CI: 1.3-2.7). Alosetron (OR: 2.2; 95% CI: 1.9-2.6) and tegaserod (OR: 1.4; 95% CI: 1.2-1.5) showed a significant effect in women. We recommend the use of tegaserod for women with irritable bowel syndrome with constipation and alosetron for women with severe irritable bowel syndrome with diarrhoea. Antidepressants can be beneficial for irritable bowel syndrome with diarrhoea patients with severe symptoms. Loperamide can be recommended in painless diarrhoea. Evidence is weak to recommend the use of bulking agents in the treatment of irritable bowel syndrome with constipation.