BACKGROUND AND AIMS:
Few treatments have demonstrated efficacy and safety for diarrhea-predominant irritable bowel syndrome (IBS-D). A phase 3, randomized, double-blind, placebo-controlled trial was performed to evaluate the safety and efficacy of repeat treatment with the nonsystemic antibiotic rifaximin.
The trial included adults with IBS-D, mean abdominal pain and bloating scores of 3 or more, and loose stool, located at 270 centers in the United States and Europe from February 2012 through June 2014. Those responding to a 2 week course of open-label rifaximin 550 mg 3 times daily who then relapsed during an observation phase (up to 18 weeks) were randomly assigned to groups given repeat treatments of rifaximin 550 mg or placebo, 3 times daily for 2 weeks. The primary endpoint was percentage of responders after first repeat treatment, defined as a decrease in abdominal pain of 30% or more from baseline and a decrease in frequency of loose stools of 50% or more from baseline, for 2 or more weeks during a 4-week posttreatment period.
Of 1074 patients (44.1%) who responded to open-label rifaximin, 382 (35.6%) did not relapse, whereas 692 (64.4%) did; of these, 636 were randomly assigned to receive repeat treatment with rifaximin (n=328) or placebo (n=308). The percentage of responders was significantly greater with rifaximin than placebo (38.1% vs 31.5%, P=.03). The percentage of responders for abdominal pain (50.6% vs 42.2%, P=.018) was significantly greater with rifaximin than placebo, but not stool consistency (51.8% vs 50.0%, P=.42). Significant improvements were also noted for prevention of recurrence, durable response, and bowel movement urgency. Adverse event rates were low and similar between groups.
In a phase 3 study of patients with relapsing symptoms of IBS-D, repeat rifaximin treatment was efficacious and well tolerated.
Copyright © 2016 AGA Institute. Published by Elsevier Inc. All rights reserved.