Study of RNIB21 Combining Rifaximin and N-Acetylcysteine to Treat Adults With Irritable Bowel Syndrome With Diarrhea

What this Trial Is About

Researchers are evaluating the combination of rifaximin and N-acetyl-L-cysteine NAC to treat patients with irritable bowel syndrome with diarrhea IBS-D. This phase 2b, multi-center, randomized, double-blind, placebo-controlled study aims to see if this combination reduces IBS-D symptoms better than rifaximin alone. Rifaximin is an FDA-approved antibiotic for IBS-D, while NAC is a dietary supplement used for other conditions and is not yet approved for IBS-D treatment in combination with rifaximin. Participants will be randomly assigned to one of three groups rifaximin 66 mg plus NAC 560 mg three times daily, rifaximin 132 mg plus NAC 560 mg three times daily, or a placebo taken three times daily. The study includes a screening phase, a 14-day treatment phase with visits at the start, week 1, and week 2, followed by a 14-week follow-up phase with an end-of-study visit. A subset of patients will provide blood samples to study how the drugs are processed in the body. Participants will report their abdominal pain daily using a pain scale and record stool consistency using the Bristol Stool Scale through a smartphone app and questionnaires. The main outcome is the proportion of patients who experience relief in both abdominal pain and stool consistency during the 4 weeks after treatment. Researchers will monitor safety and symptom changes throughout the study, which lasts approximately 14 weeks for each participant.

Efficacy of Rifaximin With NAC in IBS-D