Rifaximin plus N-acetylcysteine (NAC) for diarrhea-predominant IBS

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This phase 2b, randomized, double-blind, placebo-controlled trial compares two doses of rifaximin combined with NAC versus placebo given three times daily for 14 days in adults with IBS-D. Patients are randomized 1:1:1 and followed through 14 weeks, with the primary evaluation period covering the 28 days after completing therapy. Daily patient-reported outcomes on abdominal pain and stool consistency are collected via REDCap, and a blinded pharmacokinetics subset of 24 patients will provide serial blood samples to characterize rifaximin and NAC levels. The primary endpoint is the proportion of patients who meet responder criteria for both abdominal pain and stool consistency during the 4-week primary evaluation period, per FDA guidance.

Why it matters

Who can join: the full rules

Inclusion Criteria:

1. Male or non-pregnant, non-lactating female patients ≥ 18 years of age
2. Diagnosed with IBS confirmed by the Rome IV criteria, with associated symptoms of diarrhea as noted below in 4(b).
3. Do not have adequate relief of IBS symptoms of abdominal pain, stool consistency or stool frequency
4. Have daily IBS symptom scores during screening as below:

   1. Weekly average score of worst daily abdominal pain \>3.0 on a 0-10 point scale
   2. At least one stool with a consistency of Type 6 or 7 on the Bristol

Exclusion Criteria:

1. Present with the following symptoms of IBS with constipation:

   1. Less than 3 bowel movements a week,
   2. Hard or lumpy stools, and
   3. Excessive straining during a bowel movement.
2. History of inflammatory bowel disease, celiac disease, GI surgery (except cholecystectomy and/or appendectomy)
3. Evidence of active duodenal ulcer, gastric ulcer, diverticulitis, or active infectious gastroenteritis
4. Current diagnosis of asthma
5. Current user of NAC and/or rifaximin
6. Systemic antibiotic use in the last month
7. Not currently on a prokinetic drug
8. A significant medical condition including but not limited to hepatic, uncontrolled diabetes, renal, cardiovascular, pulmonary, uncontrolled thyroid disease. or psychiatric disease, which in the opinion of investigator precludes study participation

Where it's running

• Cedars-Sinai Medical Center
  Los Angeles, California, United States Recruiting

Study contacts

• Study coordinator: Mark Pimentel, MD
• Email: mastprogrram@cshs.org
• Phone: 310.423.0617

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.