Rifaximin is a semisynthetic, rifamycin-based non-systematic antibiotic, meaning that the drug will not pass the gastrointestinal wall into the circulation as is common for other types of orally administered antibiotics. It is primarily used to treat diarrhea caused by E. coli, but recent studies published in the American Journal of Gastroenterology suggest its efficacy in relieving chronic functional symptoms of bloating and flatulence that are common in gastrointestinal disorders, such as Irritable Bowel Syndrome.

It is currently sold under the brand name Xifaxan® by Salix Pharmaceuticals.

References

• Sharara A, Aoun E, Abdul-Baki H, Mounzer R, Sidani S, ElHajj I. A Randomized Double-Blind Placebo-Controlled Trial of Rifaximin in Patients with Abdominal Bloating and Flatulence. The American Journal of Gastroenterology, 101(2):326 — February 2006.
• Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. National Committee for Clinical Laboratory Standards, Sixth Edition, Wayne PA. — January 2003
• Micromedex information on rifaximin
• FDA label approved for Xifaxan (PDF warning)