NCT06727422 Efficacy of Rifaximin With NAC in IBS-D
| NCT ID | NCT06727422 |
| Status | Recruiting |
| Phase | Phase 2 |
| Sponsor | Mark Pimentel, MD |
| Condition | IBS (Irritable Bowel Syndrome) |
| Study Type | INTERVENTIONAL |
| Enrollment | 225 participants |
| Start Date | 2026-02-04 |
| Primary Completion | 2026-08-01 |
Eligibility & Interventions
Eligibility Fast-Check
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What to Expect as a Participant
You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.
In Phase 2, researchers evaluate early signs of effectiveness. You may be randomized to receive the active treatment or a comparator. Monitoring continues closely.
This trial targets 225 participants in total. It began in 2026-02-04 with a primary completion date of 2026-08-01.
⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.
Brief Summary
The purpose of this study is to examine the effectiveness of using a combination of a drug, rifaximin and a dietary supplement, N-acetyl-L-cysteine (NAC), to treat patients with irritable bowel syndrome with diarrhea (IBS-D). Rifaximin is one of the standard treatments for IBS-D and is FDA approved. While rifaximin is safe and effective for treating symptoms in patients with IBS-D, many patients find that their symptoms may not completely resolve, or may come back after a period of time. This research study is designed to test the investigational use of a combination of rifaximin and NAC. The combination of rifaximin and NAC is not approved by the U.S. Food and Drug Administration (FDA) for the treatment of IBS-D, and the effects of taking both medications together are unknown. However, the two medications are approved for use separately, as detailed below. Rifaximin is the only antibiotic approved by the FDA for the treatment of IBS-D. Rifaximin (at a dose of 550 mg by mouth three times daily for 14 days) is approved by the FDA for the treatment of IBS-D. Rifaximin (at a dose of 200 mg per mouth three times daily for 3 days) is FDA approved for the treatment of traveler's diarrhea. Rifaximin at a dose of 200 mg per mouth three times daily is not approved by the FDA for the treatment of IBS-D. NAC is approved by the FDA to treat acetaminophen overdose (72-hour oral and 21-hour intravenous (IV) regimens), and for use in breaking up mucus in the lungs in patients with chronic obstructive pulmonary disease (COPD) and other lung conditions such as bronchitis. NAC is also available over-the-counter in 600 mg and 900 mg capsules as a dietary supplement, although over-the-counter use is not regulated by the FDA. This study will utilize the 600 mg dietary supplement capsules. The Investigators want to know if using a combination of rifaximin and NAC will give better results in decreasing IBS-D symptoms than using rifaximin alone. As NAC is used to break up mucus in the lungs, and the Investigators want to see if this can also break up the mucus layer in the small intestine, and therefore potentially increase the effectiveness of rifaximin. The Investigators will be testing 2 doses to determine which dose is most effective. participants are being asked to take part in this research study because participants were diagnosed with IBS-D.
Eligibility Criteria
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
Contact & Investigator
Frequently Asked Questions
Who can join the NCT06727422 clinical trial?
This trial is open to participants of all sexes, aged 18 Years or older, studying IBS (Irritable Bowel Syndrome). Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.
What phase is the NCT06727422 trial and what does that mean for participants?
Phase 2 trials evaluate whether the treatment shows signs of effectiveness while continuing to monitor safety. More participants are enrolled than in Phase 1 to help refine the treatment protocol.
Is NCT06727422 currently recruiting?
Yes, NCT06727422 is actively recruiting participants. Contact the research team at mastprogrram@cshs.org for enrollment information.
Where is the NCT06727422 trial being conducted?
This trial is being conducted at Los Angeles, United States.
Who is sponsoring the NCT06727422 clinical trial?
NCT06727422 is sponsored by Mark Pimentel, MD. The trial plans to enroll 225 participants.