Rifaximin helps improve symptoms of IBS with diarrhoea

Treatment with rifaximin appears to produce significant reductions in multiple, concurrent symptoms of irritable bowel syndrome (IBS) with diarrhoea, according to a study that uses a novel tri-symptom endpoint.

Researchers conducted post hoc analyses of two randomized, double-blind, placebo-controlled trials and the open-label phase of a randomized, double-blind, placebo-controlled trial. The trials involved adult participants with IBS-D who received a 2-week course of rifaximin 550 mg three times a day.

Endpoints included individual and composite responses for abdominal pain (mean weekly improvements from baseline of ≥30 percent, ≥40 percent, or ≥50 percent), bloating (mean weekly improvements from baseline of ≥1 or ≥2 points; or ≥30 percent, ≥40 percent, or ≥50 percent), stool consistency (mean weekly average stool consistency score <3 or <4), and urgency (improvement from baseline of ≥30 percent or ≥40 percent in percentage of days with urgency). These endpoints were evaluated for ≥2 of the first 4 weeks after treatment and then weekly for 12 weeks.

The total study population included 1,258 patients from the double-blind trials (rifaximin: n=624; placebo: n=634) and 2,438 from the open-label trial. Significantly more patients who received rifaximin vs placebo showed response for bloating or urgency (p≤0.03). The same was true for response for the composite abdominal pain and bloating (p<0.05).

The percentage of tri-symptom composite endpoint responders (abdominal pain, bloating, and faecal urgency) was also significantly greater in the rifaximin group than in the placebo group (p=0.001). Of note, significantly more rifaximin-treated participants significantly achieved response (≥30 percent composite tri-symptom threshold) as early as 1 week post-treatment, with significance maintained through ≥5 weeks after treatment.

Results for the open-label trial were consistent with those of the double-blind trials.