Rifaximin, a minimally absorbed antibiotic that stays in the gut has been found to provide long-lasting relief for patients with irritable bowel syndrome (IBS), researchers have revealed in NEJM (New England Journal of Medicine). IBS patients experienced relief long after they had stopped taking the drug.

The authors report that patients reported relief from IBS symptoms for up to 10 weeks after completing rifaximin treatment. They specifically reported considerable reductions in abdominal pain, bloating, and better stool consistency.

The authors explain that the idea that bacteria play a major role in IBS has been disputed over the last ten years. These latest findings confirm that intestinal bacteria, also known as the gut microbiome, are closely involved in IBS symptoms.

Irritable bowel syndrome, also known as spastic colitis, nervous colon syndrome, or IBS is a chronic (long-term) gastrointestinal disorder that causes bloating, mucous in stools, irregular bowel habits (diarrhea and constipation), and abdominal pain. In the majority of cases patients have periods during their lives when the symptoms wax and wane. Although IBS can be extremely unpleasant, it does not usually lead to serious complications. However, it can cause absenteeism (from work), serious fatigue and make the patient's life a misery. Fortunately, the majority of patients do not have severe symptoms.

Approximately 30 million Americans are known to be affected by IBS. This latest therapy was developed at Cedars-Sinai Medical Center.

Lead author, Mark Pimentel, M.D., GI Motility Program director and principal investigator of the clinical trials at Cedars-Sinai, said that their findings demostrate that targeted antibiotics are both safe and effective for long-lasting IBS relief.

William D. Chey, M.D., professor in the Department of Internal Medicine at the University of Michigan, said:

"This represents a big change in the way we think about and treat IBS."

Chey added that currently available treatments, such as fiber supplements or dietary changes do not provide satisfactory relief for a significant number of patients - as soon as treatment stops, symptoms tend to come rushing back. With this new treatment, however, even when they have stopped taking the meidcation, patients continue feeling better.

The study involved 660 patients in two double-blind trials. All the IBS participants with mild to moderate diarrhea and bloating were randomly selected to receive a three times daily dose of 550milligrams of rifaximin or a placebo (dummy drug) for a period of two weeks. They were then monitored for a further ten weeks.

40% of patients on rifaximin experienced relief immediately from abdominal pain, loose/watery stools and bloating. The majority of them had symptom relief that continued for several weeks after completing their antibiotic treatment.

Because IBS causes have been unclear, doctors have tended to focus on treatments which either slow down or speed up the digestive process, depending on whether their IBS provokes more diarrhea or constipation.

A previous study had found an association between bloating and bacterial fermentation in the intestine related to small intestine bacterial overgrowth (SIBO). Other studies have suggested that the bacteria which exist within the small and large intestines of individuals with IBS are not the same as those within the intestines of other people.

Rifaximin, which is marketed by Salix Pharmaceuticals Inc., is currently approved by the FDA to treat hepatic encephalopathy and traveler's diarrhea.

"Rifaximin Therapy for Patients with Irritable Bowel Syndrome without Constipation"
Mark Pimentel, M.D., Anthony Lembo, M.D., William D. Chey, M.D., Salam Zakko, M.D., Yehuda Ringel, M.D., Jing Yu, Ph.D., Shadreck M. Mareya, Ph.D., Audrey L. Shaw, Ph.D., Enoch Bortey, Ph.D., and William P. Forbes, Pharm.D. for the TARGET Study Group
N Engl J Med 2011; 364:22-32January 6, 2011

Written by Christian Nordqvist