Diarrhea medicine may ease irritable bowel symptoms for some people

Monday, January 17, 2011; 7:25 PM


Antibiotic that treats diarrhea may ease gut symptoms for some people

THE QUESTION Diet and lifestyle changes, fiber supplements and psychotherapy have all been tried by people with irritable bowel syndrome, often with little success. Might an antibiotic that targets gut bacteria be a viable option to relieve the cramping, bloating and diarrhea that can be characteristic of this chronic gastrointestinal disorder?

THIS STUDY involved 1,260 adults, most in their mid-40s, who had irritable bowel syndrome without constipation. They were randomly assigned to take rifaximin (Xifaxan) or a placebo three times a day for two weeks. A month later, more people who had taken rifaximin, rather than the placebo, reported overall symptom relief: 41 percent vs. 32 percent. Relief from bloating, considered a difficult symptom to treat, was achieved by 40 percent of those who had taken the antibiotic, compared with 30 percent of the others. Participants reported symptom relief for up to 10 weeks after taking the drug. Adverse effects, such as headache, nausea and upper respiratory infections, were no more common in the antibiotic group than the placebo group.

WHO MAY BE AFFECTED? People with irritable bowel syndrome, estimated to affect 20 percent of adults in the United States, women more often than men. Precisely what causes irritable bowel is unknown. Some experts think it's the result of intestinal sensitivity to certain foods and stress. Others believe that intestinal bacteria, so-called "gut flora," trigger symptoms.

CAVEATS The study was a Phase 3 clinical trial designed to test the safety and effectiveness of rifaximin in treating irritable bowel; the drug currently has Food and Drug Administration approval for treating and preventing traveler's diarrhea. The study did not test people who had the type of irritable bowel syndrome that includes constipation. Data came from the participants' assessments of symptom relief. The study was funded by Salix Pharmaceuticals, which makes Xifaxan; five of the 10 authors had received fees from the company, and the others were its employees.

FIND THIS STUDY Jan. 6 issue of the New England Journal of Medicine (www.nejm.org).

LEARN MORE ABOUT irritable bowel syndrome at www.digestive.niddk.nih.gov and www.mayoclinic.com.

- Linda Searing

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.

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