IBS Study

Cedars-Sinai researchers have found that a nonabsorbable antibiotic -- one that stays in the gut -- can be an effective long-term treatment for Irritable Bowel Syndrome (IBS), a disease affecting more than 20 percent of Americans.

The study, appearing this week in the October 17 issue of the Annals of Internal Medicine, is the first to demonstrate benefits from antibiotic use even after the course of treatment has ended, supporting previously published research that identified small intestine bacterial overgrowth as a cause of the disease.

The randomized, double-blind, placebo-controlled study involved 87 participants, all of whom met specific multinational guidelines for diagnosis of IBS. They received 400 mg of the antibiotic rifaximin three times a day for 10 days or a placebo.

Researchers found that the rifaximin not only led to significant improvement in global IBS symptoms during the 10 days it was administered, but also that the benefit continued for the 10 weeks of follow up when no antibiotic was given, showing sustained benefit.

"The fact that the benefit of the targeted antibiotic continued even after it was stopped provides evidence that the antibiotic was acting on a source of the problem: excess bacteria in the gut," said Mark Pimentel, M.D., director of the GI Motility Program at Cedars-Sinai and the study's principal investigator. "This finding offers a new treatment approach -- and a new hope -- for people with IBS."

Rifaximin, an antibiotic that is FDA-approved for travelers' diarrhea in this country, is made by Salix Pharmaceuticals, Inc., which also provided funding for the study. The discovery related to the use of rifaximin for IBS was made at Cedars-Sinai by Pimentel. Cedars-Sinai holds patent rights to this discovery and has licensed rights to the invention to Salix.

Other authors from Cedars-Sinai include Sandy Park, James Mirocha and Yuthana Kong. Sunanda V. Kane from the University of Chicago also participated in the study.