PHILADELPHIA, October 17, 2006 – A new study found that patients reported greater global improvements in irritable bowel syndrome (IBS) symptoms and less bloating after taking rifaximin than patients taking placebo. The randomized, double-blind study is the first to demonstrate a sustained benefit of an antibiotic for IBS symptoms after treatment is stopped.
The study, "The Effect of a Nonabsorbed Oral Antibiotic (Rifaximin) on the Symptoms of the Irritable Bowl Syndrome," is published in the October 17, 2006, issue of Annals of Internal Medicine. The entire article is available to the public on October 17, 2006, at http://www.annals.org/cgi/content/full/145/8/557.
IBS is one of the most common chronic medical conditions – affecting about 15 to 20 percent of the population. Its cause is unknown but some IBS patients exhibit an overabundance of bacteria in the small bowel of the colon.
"This is the first possible treatment for the potential causative factors of IBS," said Mark Pimentel, MD, FRCP(C), Director, GI Motility Program, Cedars-Sinai Medical Center, the study's lead author. "Patients can take the antibiotic for a brief period of time and experience benefit for ten weeks."
In the study, 87 patients with IBS between the ages of 18 and 65 received 1200 mg of rifaximin (an antibiotic that works in the gut without being absorbed into the blood stream) a day or a placebo for 10 days. Patients reported their symptoms for the next 10 weeks.
More than 50 percent improvement in symptoms was reported by more patients who took rifaximin (37.2 percent) than by those who took placebo (15 percent). However, the researchers did not detect a difference in symptoms of diarrhea or constipation. Rifaximin is FDA approved for the treatment of travelers' diarrhea.
The nonabsorbed antibiotic seems to cause few side effects, another benefit for patients.
"Rifaximin doesn't get into the blood stream and interact with other medications," Dr. Pimentel said.
The drug helped patient Cynthia Greenspan get her life back.
"After the first five days of taking the medication, I started feeling better," said Greenspan. "After 10 days, I couldn't believe how much better I felt."
The researchers caution that while the study demonstrates improvement for a relatively small group of IBS patients, side effects may be difficult to assess in such a small study when considering the potentially large patient population with IBS. A larger and longer study is necessary to evaluate the effects of treatment for other symptoms, such as constipation.
In a separate editorial, Douglas A. Drossman, M.D., wrote, "Demonstrating benefit from a short course of an antibiotic for a sustained period of time in unselected patients with IBS is certainly novel and important."
Annals of Internal Medicine is one of the most widely cited peer-reviewed medical journals in the world. The journal has been published for 79 years and accepts only 7 percent of the original research studies submitted for publication. Annals of Internal Medicine is published by the American College of Physicians, the nation's largest medical specialty society.
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