Review of Rifaximin: Latest Treatment Frontier for Irritable Bowel Syndrome Mechanism of Action and Clinical Profile

Background: Irritable bowel syndrome is classified as a functional gastrointestinal disorder with the primary symptom of abdominal pain in conjunction with bloating and bowel movement disorder. It affects up to 15% of the world’s population. Among its subtypes, the most common is diarrhoea predominant. However, the current treatment options for diarrhoea-predominant irritable bowel syndrome have had not very promising results; most, such as antispasmodics, only provide partial symptomatic relief. Treatment with antidepressants and alosetron (a 5HT3 antagonist) has shown the most promise to date. The latest drug to be approved for the treatment of irritable bowel syndrome-diarrhoea is rifaximin, which was approved in May 2015. It is a minimally absorbed antibiotic that is used to change the gut microbiota. Small intestinal bacterial overgrowth is one of the causes suggested for irritable bowel syndrome, particularly for the diarrhoea-predominant type. There are various methods for detecting bacterial overgrowth, the simplest of which is breath tests. Rifaximin has been shown to be of benefit to these patients. Purpose: The purpose of the study is to discuss the potential mechanism of action of rifaximin, a minimally absorbed antibiotic. In addition, we evaluate the various clinical trials undertaken to study the efficacy and safety profile of rifaximin.

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Mechanism of action and therapeutic benefit of rifaximin in patients with irritable bowel syndrome: a narrative review

Therapeutic Advances in Gastroenterology ◽

10.1177/1756284819897531 ◽

2020 ◽

Vol 13 ◽

pp. 175628481989753 ◽

Cited By ~ 2

Author(s):

William D. Chey ◽

Eric D. Shah ◽

Herbert L. DuPont

Keyword(s):

Irritable Bowel Syndrome ◽

Gut Microbiota ◽

Mechanism Of Action ◽

Bacterial Overgrowth ◽

Gastrointestinal Disorder ◽

Small Intestinal Bacterial Overgrowth ◽

The United States ◽

Clinical Effects ◽

Healthy Individuals ◽

Irritable Bowel

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with a multifactorial pathophysiology. The gut microbiota differs between patients with IBS and healthy individuals. After a bout of acute gastroenteritis, postinfection IBS may result in up to approximately 10% of those affected. Small intestinal bacterial overgrowth (SIBO) is more common in patients with IBS than in healthy individuals, and eradication of SIBO with systemic antibiotics has decreased symptoms of IBS in some patients with IBS and SIBO. The nonsystemic (i.e. low oral bioavailability) antibiotic rifaximin is indicated in the United States and Canada for the treatment of adults with IBS with diarrhea (IBS-D). The efficacy and safety of 2-week single and repeat courses of rifaximin have been demonstrated in randomized, placebo-controlled studies of adults with IBS. Rifaximin is widely thought to exert its beneficial clinical effects in IBS-D through manipulation of the gut microbiota. However, current studies indicate that rifaximin induces only modest effects on the gut microbiota of patients with IBS-D, suggesting that the efficacy of rifaximin may involve other mechanisms. Indeed, preclinical data reveal a potential role for rifaximin in the modulation of inflammatory cytokines and intestinal permeability, but these two findings have not yet been examined in the context of clinical studies. The mechanism of action of rifaximin in IBS is likely multifactorial, and further study is needed.

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Rational investigations in irritable bowel syndrome

Frontline Gastroenterology ◽

10.1136/flgastro-2019-101211 ◽

2019 ◽

Vol 11 (2) ◽

pp. 140-147 ◽

Cited By ~ 3

Author(s):

Christopher J Black ◽

Alexander C Ford

Keyword(s):

Irritable Bowel Syndrome ◽

Bacterial Overgrowth ◽

Gastrointestinal Disorder ◽

Small Intestinal Bacterial Overgrowth ◽

Routine Practice ◽

Faecal Calprotectin ◽

Lactose Malabsorption ◽

Alarm Features ◽

Irritable Bowel ◽

Hydrogen Breath Tests

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder which accounts for a substantial proportion of a gastroenterologist’s time in the outpatient clinic. However, there is variability in approaches to diagnosis and investigation between physicians, dependent on expertise. Many patients express disappointment over the lack of a patient-centred approach. Consequently, there have been calls for the care of patients with IBS to be standardised, a process which aims to promote high-quality and high-value care. Making an early diagnosis, based on a clinical assessment of symptoms, while limiting use of investigations, are key tenets of this process. Exhaustive investigation to exclude all organic pathology is unnecessary, and may be counterproductive. Routine blood tests in suspected IBS have low yield, but are an acceptable part of routine practice. All patients should have coeliac serology tested, regardless of their predominant stool form. Patients with diarrhoea should have a faecal calprotectin measured, and should proceed to colonoscopy to exclude inflammatory bowel disease (IBD) if this is positive. Beyond this, the need for investigations should be made on a case-by-case basis, contingent on the reporting of known risk factors for organic pathology. Colonoscopy should be considered in any patient with alarm features for colorectal cancer, and in those whose clinical features are suggestive of microscopic colitis. A 23-seleno-25-homotaurocholic acid (SeHCAT) scan should be considered in patients with IBS-D, a third of whom may actually have bile acid diarrhoea. There is no role for routine hydrogen breath tests for lactose malabsorption or small intestinal bacterial overgrowth.

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Rifaximin Therapy of Irritable Bowel Syndrome

Clinical Medicine Insights Gastroenterology ◽

10.4137/cgast.s7382 ◽

2012 ◽

Vol 5 ◽

pp. CGast.S7382 ◽

Cited By ~ 3

Author(s):

Hoonmo L. Koo ◽

Saman Sabounchi ◽

David B. Huang ◽

Herbert L. Dupont

Keyword(s):

Irritable Bowel Syndrome ◽

Safety Data ◽

Bacterial Overgrowth ◽

Gastrointestinal Disorder ◽

Small Intestinal Bacterial Overgrowth ◽

In Vitro Susceptibility ◽

Intestinal Bacterial Overgrowth ◽

Small Intestinal ◽

Irritable Bowel

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder characterized by abdominal pain and altered bowel habits in the absence of specific organic pathology. Although the underlying pathogenesis of IBS is not well-understood, small intestinal bacterial overgrowth (SIBO) or other abnormalities in the gut flora is believed to contribute to the development of a subset of IBS cases. Rifaximin is a poorly absorbed antimicrobial with activity against enteric pathogens. A number of studies have shown a significant improvement in IBS symptoms with antibiotic therapy including rifaximin. In this review, we discuss the pharmacokinetics, in vitro susceptibility profile, and efficacy and safety data from clinical trials of rifaximin treatment of IBS.

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