Rifaximin could be treatment course for IBS

January 21, 2011

A 2-week course of rifaximin (Xifaxan, Salix Pharmaceuticals) relieved bloating and other symptoms of irritable bowel syndrome for more than 2 months after treatment ended, according to research published January 6 in the New England Journal of Medicine. Rifaximin is the first treatment that targets the underlying cause of IBS, rather than just treating the symptoms, researchers said.

A 2-week course of rifaximin (Xifaxan, Salix Pharmaceuticals) relieved bloating and other symptoms of irritable bowel syndrome (IBS) for more than 2 months after treatment ended, according to research published January 6 in the New England Journal of Medicine. Rifaximin is the first treatment that targets the underlying cause of IBS, rather than just treating the symptoms, researchers said.

Two identically designed, phase-3, double-blind, placebo-controlled trials involved 1,260 individuals diagnosed with IBS but no constipation. They took either 550 mg of rifaximin or a placebo 3 times daily for 2 weeks and were followed for an additional 10 weeks. In the 4 weeks after treatment, nearly 41% of those who received rifaximin in the 2 trials reported adequate relief of IBS symptoms, compared with about 32% of the placebo group. About 40% in the rifaximin group said they found relief from bloating, compared with about 30% in the placebo group for both trials.

“This research shows that antibiotics work for patients with IBS, suggesting the intestinal microbiota has a role in causing this condition,” said Yehuda Ringel, MD, a gastroenterologist and associate professor of medicine at the University of North Carolina and a co-author of the study. “The effect lasted for 10 weeks after discontinuation of the medication, suggesting we are changing something in the underlying abnormality.”

Raleigh, N.C.-based Salix Pharmaceuticals funded the research. FDA is reviewing the company’s supplemental New Drug Application for rifaximin 550-mg tablets for the proposed indication of the treatment of IBS without constipation. The drug currently is approved for treating traveler’s diarrhea and hepatic encephalopathy, a brain disorder caused by liver disease.