Rifaximin Treatment in Bloating Predominant Functional Bowel Disorders

NCT07522255 | Not Yet Recruiting Phase 3

• 1 other identifier: Si 917/2025
• Study Type: interventional
• Target: 78
• Locations: 1 country
• Sites: 1

Brief Summary

This randomized, double-blind, placebo-controlled trial will evaluate whether a 14-day course of rifaximin improves bloating in adult patients with Rome IV functional bowel disorders in whom bloating is the predominant symptom. Eligible participants with irritable bowel syndrome, functional constipation, or functional abdominal bloating/distension and bothersome bloating despite adequate bowel movement management will be assigned in a 1:1 ratio to rifaximin 550 mg three times daily or matching placebo for 2 weeks. The primary endpoint is the proportion of participants with bloating response, defined as at least a 1-point reduction from baseline in a 7-point Likert bloating score at the end of treatment.

Conditions

Bloating; Rifaximin; Functional Bowel Disorder; Constipation; Irritable Bowel Syndrome

Keywords

Rifaximin; Bloating; Functional bowel disorder

Outcome Measures

Primary Outcomes (1)

• Bloating responder rate

  Bloating responder is defined as at least a 1-point reduction from baseline to week 2 in bloating symptom severity measured using a 7-point Likert scale for bothersomeness of bloating (range 0 to 6; higher scores indicate worse symptoms). Score categories are 0 = not at all, 1 = hardly, 2 = somewhat, 3 = moderately, 4 = a good deal, 5 = a great deal, and 6 = a very great deal.

  From enrollment to the end of treatment at 2 weeks

Secondary Outcomes (18)

• Abdominal pain response rate

  From enrollment to the end of treatment at 2 weeks

• Change in Global IBS Symptoms (IBS patients)

  From enrollment to the end of treatment at 2 weeks

• Change in global constipation symptoms (constipation patients)

  From enrollment to the end of treatment at 2 weeks

• Treatment satisfaction

  End of treatment at 2 weeks

• Change in Psychological Symptoms

  From enrollment to the end of treatment at 2 weeks

Study Arms (2)

Rifaximin

EXPERIMENTAL

Participants randomized to this arm receive rifaximin 550 mg orally three times daily for 2 weeks.

Drug: Rifaximin (drug)

Placebo

PLACEBO COMPARATOR

Participants randomized to this arm receive an identical placebo orally three times daily for 2 weeks.

Drug: Placebo

Interventions

Rifaximin (drug) DRUG

Participants randomized to this arm receive rifaximin 550 mg orally three times daily for 2 weeks. Allocation is randomized and double-blinded.

Rifaximin

Placebo DRUG

Matching placebo administered orally three times daily for 14 days.

Placebo

Eligibility Criteria

• Age: 18 Years - 80 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adults aged 18 to 80 years.
• Rome IV diagnosis of irritable bowel syndrome, functional constipation, or functional abdominal bloating/distension.
• Bothersome bloating with baseline severity of at least 3 on a 7-point Likert scale after adequate constipation treatment, defined as stool frequency from at least 3 times/week to 3 times/day and Bristol Stool Form Scale type 3-5.
• Colonoscopy, CT colonography, or barium enema performed if clinically indicated as part of standard evaluation for bowel symptoms.

You may not qualify if:

• History of major gastrointestinal surgery, except appendectomy or laparoscopic cholecystectomy.
• Inflammatory bowel disease or other inflammatory gastrointestinal conditions.
• Current use of, or inability to discontinue, medications that may affect intestinal microbiota or gas measurements, including antibiotics, proton pump inhibitors, probiotics, lactulose, NSAIDs, or metformin.
• Current use of, or inability to discontinue, medications that may affect bloating symptoms, including simethicone, simethicone-containing antispasmodics, or antidiarrheal medications.
• Underlying conditions known to affect intestinal microbiota composition, including cirrhosis, uncontrolled diabetes mellitus, end-stage renal disease, obesity, malignancy, or psychiatric disorders.
• Opioid-induced constipation.
• Known allergy to rifaximin.

Sponsors & Collaborators

• Mahidol University: lead

Study Sites (1)

Faculty of Medicine Siriraj Hospital, Mahidol University

Bangkok Noi, Bangkok, 10700, Thailand

Location

Related Publications (6)

• Mearin F, Lacy BE, Chang L, Chey WD, Lembo AJ, Simren M, Spiller R. Bowel Disorders. Gastroenterology. 2016 Feb 18:S0016-5085(16)00222-5. doi: 10.1053/j.gastro.2016.02.031. Online ahead of print.

  PMID: 27144627 BACKGROUND

• Lacy BE, Chang L, Rao SSC, Heimanson Z, Sayuk GS. Rifaximin Treatment for Individual and Multiple Symptoms of Irritable Bowel Syndrome With Diarrhea: An Analysis Using New End Points. Clin Ther. 2023 Mar;45(3):198-209. doi: 10.1016/j.clinthera.2023.01.010. Epub 2023 Mar 14.

  PMID: 36922331 BACKGROUND

• Chey WD, Shah ED, DuPont HL. Mechanism of action and therapeutic benefit of rifaximin in patients with irritable bowel syndrome: a narrative review. Ther Adv Gastroenterol. 2020 Jan 23;13:1756284819897531. doi: 10.1177/1756284819897531. eCollection 2020.

  PMID: 32047534 BACKGROUND

• Melchior C, Hammer H, Bor S, Barba E, Horvat IB, Celebi A, Drug V, Dumitrascu D, Kalkan IH, Hauser G, Lionis C, Livovsky D, Mari A, Mulak A, Surdea-Blaga T, Tack J, Vanuytsel T, Savarino EV, Zarate-Lopez N, Hammer J, Dickman R. European Consensus on Functional Bloating and Abdominal Distension-An ESNM/UEG Recommendations for Clinical Management. United European Gastroenterol J. 2025 Nov;13(9):1613-1651. doi: 10.1002/ueg2.70098. Epub 2025 Aug 22.

  PMID: 40844856 BACKGROUND

• Moshiree B, Drossman D, Shaukat A. AGA Clinical Practice Update on Evaluation and Management of Belching, Abdominal Bloating, and Distention: Expert Review. Gastroenterology. 2023 Sep;165(3):791-800.e3. doi: 10.1053/j.gastro.2023.04.039. Epub 2023 Jul 13.

  PMID: 37452811 BACKGROUND

• Arora U, Sachdeva K, Garg P, Baitha U, Kedia S, Kalaivani M, Ahuja V, Kumar A, Ranjan P, Vikram NK, Sinha S, Biswas A, Wig N. Efficacy of Rifaximin in Patients With Abdominal Bloating or Distension: A Systematic Review and Meta-analysis. J Clin Gastroenterol. 2024 Apr 1;58(4):360-369. doi: 10.1097/MCG.0000000000001872.

  PMID: 37310270 BACKGROUND

MeSH Terms

Conditions

Irritable Bowel Syndrome; Constipation

Interventions

Rifaximin; Pharmaceutical Preparations

Condition Hierarchy (Ancestors)

Colonic Diseases, Functional; Colonic Diseases; Intestinal Diseases; Gastrointestinal Diseases; Digestive System Diseases; Signs and Symptoms, Digestive; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Rifamycins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Lactams, Macrocyclic; Macrocyclic Compounds; Polycyclic Compounds

Study Officials

• Monthira Maneerattanaporn, M.D.

  Mahidol University

  PRINCIPAL INVESTIGATOR

• Pubet Weeranawin, M.D.

  Mahidol University

  STUDY CHAIR

• Somchai Leelakusolvong, M.D.

  Mahidol University

  STUDY CHAIR

• Tanawat Geeratragool, M.D.

  Mahidol University

  STUDY CHAIR

Central Study Contacts

Monthira Maneerattanaporn, M.D.

CONTACT

+66 24197281; monthira.man@mahidol.ac.th

Pubet Weeranawin, M.D.

CONTACT

+66 832958042; pubet.w@gmail.com

Study Design

• Study Type: interventional
• Phase: phase 3
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: March 23, 2026
• First Posted: April 13, 2026
• Study Start: April 1, 2026
• Primary Completion (Estimated): October 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: April 13, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

TH (1)