At the American College of Gastroenterology meetings this week, researchers reported that treatment of diarrhea-predominant irritable bowel syndrome with rifaximin was associated with significant symptomatic improvements.
Irritable bowel syndrome (IBS) is a disorder that affects the large intestine, or colon. Its symptoms include cramping, abdominal pain, bloating, constipation, and diarrhea. IBS is common, affecting up to 20 percent—one in five—of adults in the United States. More women suffer from IBS than men.
It's now believed that many patients with IBS have increased microbes in the small intestine, which suggested that antibiotic treatment may prove effective for the management of IBS. Rifaximin is a semisynthetic oral antibiotic that is poorly absorbed from the gastrointestinal tract and approved for the treatment of traveler’s diarrhea.
In a clinical trial known as TARGET 3 that included 2,579 patients, a total of 42% of patients responded to 2 weeks of treatment with rifaximin. When the patients relapsed following treatment they were randomized to a second 2-week course of treatment with rifaximin or placebo, and 33% of rifaximin treated patients responded to treatment.
After the second 2-week treatment course, those who again relapsed were re-randomized to the active treatment or placebo, and 37% of the rifaximin group responded compared with 29% of the placebo group the researchers reported.
In summary, rifaximin treatment was effective, well tolerated and did not need to be taken chronically but patients could be retreated. Rifaximin is currently approved for travelers' diarrhea, and an FDA ruling on approval for IBS is expected in February 2015.
Reference: Lembo et al. Efficacy and Safety of Repeat Treatment with Rifaximin for Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D): Results of the TARGET 3 Study. American College of Gastroenterology (ACG) 2014 Annual Scientific Meeting. Abstract 45. Philadelphia, PA, October 17-22.