Rifaximin Effective for Multiple Symptoms in Irritable Bowel Syndrome With Diarrhea

Researchers analyzed the efficacy of rifaximin for relieving IBS-D symptoms, specifically abdominal pain, bloating, and bowel movement urgency.

A 2-week course of rifaximin significantly improved multiple abdominal symptoms in patients with irritable bowel syndrome with diarrhea (IBS-D), according to study results presented at Digestive Disease Week (DDW), held from May 21 to 24, 2022, in San Diego, California, and virtually.

Researchers assessed the use of rifaximin for improving a trisymptom composite endpoint of bloating, abdominal pain or discomfort, and bowel movement (BM) urgency. Using a post hoc analysis, researchers pooled data from 2 identically designed, phase 3, randomized, double-blind trials.

Study participants were adult patients with IBS-D who received rifaximin 550 mg 3 times per day or placebo for 2 weeks, followed by 4 weeks without treatment. Abdominal pain or discomfort and bloating were rated separately with a daily scale, ranging from 0 (“not at all”) to 6 (“a very great deal”).

Researchers evaluated study participants’ BM urgency on a daily basis by asking the patients, “Have you felt or experienced a sense of urgency today?” Trisymptom composite responders were defined as study participants who simultaneously experienced a 30% or greater reduction from baseline in weekly mean abdominal pain or discomfort and bloating scores, as well as a 30% or greater reduction in the percentage of days with BM urgency for 2 or more of the first 4 weeks after treatment. The same analysis was conducted with an overall threshold of a 40% or greater decrease from baseline in all 3 symptoms.

A total of 1258 patients (mean age, 45.9±14.5 years; 72.3% women) were included in the study. Participants in the rifaximin (n=624) and placebo (n=634) groups had similar baseline scores for mean daily abdominal pain (3.2-3.3), bloating (3.3), and percentage of days with urgency (82%).

A greater percentage of patients who received rifaximin had adequate relief of global IBS symptoms by 2 or more of the first 4 weeks post-treatment compared with the placebo group (40.7% vs 31.7%; P <.001).

For the trisymptom composite endpoint using 30% or greater and 40% or greater, a significantly greater percentage of patients who were treated with rifaximin were responders compared with those who received placebo for 2 or more of the first 4 weeks post-treatment.

Significant differences were observed compared with placebo for rifaximin at the 30% or greater threshold as early as 1 week after treatment (P =.01; significant through ≥5 weeks post-treatment) and at the 40% or greater threshold as early as 2 weeks after treatment (P =.02; through 4 weeks post-treatment).

Disclosure: This research was supported by Salix Pharmaceuticals. Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Lacy BE, Sayuk GS, Karsan HA, Allen C, Heimanson Z, Brenner DM. A new trisymptom composite endpoint to evaluate the efficacy of rifaximin for the multiple symptoms of irritable bowel syndrome with diarrhea (IBS-D): a pooled analysis of two randomized, phase 3 trials. Presented at: DDW 2022; May 21-24, 2022; San Diego, CA. Abstract Mo1395.