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Monday 14th November, 2005
The study findings support the theory that irritable bowel syndrome
(IBS) is caused by bacterial overgrowth in the gut.
LOS ANGELES ? Researchers at Cedars-Sinai Medical Center have
found that a nonabsorbable antibiotic ? one that stays in the gut ?
may be an effective long-term treatment for irritable bowel syndrome
(IBS), a disease affecting more than an estimated 20 percent of
Americans. The findings, which showed that participants benefited
from the antibiotic use even after the course of treatment ended,
support previously published research identifying small intestine
bacterial overgrowth (SIBO) as a possible cause of the disease.
The research was presented at the recent American College of
Gastroenterology's annual meeting in Honolulu, HI.
"This study is important as it is the first to show that the use
of targeted antibiotics results in a more significant and
long-lasting improvement in IBS symptoms," said Mark Pimentel, M.D.,
first author on the study and director of the GI Motility Program at
Cedars-Sinai. "These results clearly show that antibiotics offer a
new treatment approach ? and a new hope ? for people with IBS."
The randomized, double blind study involved 87 patients. Those on
the rifaximin experienced a 37 percent overall improvement of their
IBS symptoms as compared to 23 percent on the placebo. Among study
subjects whose primary symptom was diarrhea, those on the antibiotic
showed more than twice the improvement of those on the placebo (49
percent vs. 23 percent). Patients received the drug (or placebo) for
10 days and were then followed for a total of 10 weeks. Participants
kept a stool diary, took a questionnaire and were given methane
breath tests. The positive effects of the drug were shown to
continue throughout most of the 10-week study, not just during the
actual antibiotic course.
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Because the cause of IBS has been elusive, treatments for the
disease have historically focused on reducing its symptoms ?
diarrhea and constipation ? by giving medications that either slow
or speed up the digestive process. In 2000, Pimentel linked
bloating, the most common symptom of IBS, to bacterial fermentation,
showing that small intestine bacteria overgrowth (SIBO) may be the
causative factor in IBS (The American Journal of Gastroenterology,
To show evidence of small intestine bacterial overgrowth,
participants in both studies were given a lactulose breath test,
which monitors the level of hydrogen and methane (the gases emitted
by fermented bacteria) on the breath. In the first study, an
abnormal breath methane profile was shown to be 100 percent
predictive of constipation-predominant IBS. In the current study,
the correlation between the amount of methane and the amount of
constipation was confirmed, another key finding.
"We were pleased ? but not surprised ? with the results of this
study," said Pimentel. "The next step is to start larger,
multi-centered studies to confirm the positive results of this
study, which suggest that people can benefit from targeted
antibiotic treatment for their IBS."
Irritable Bowel Syndrome is an intestinal disorder that causes
abdominal pain or discomfort, cramping or bloating and diarrhea and
constipation. It is a long-term condition that usually begins in
adolescence or in early adult life. Episodes may be mild or severe
and may be exacerbated by stress. It is one of the top ten most
frequently diagnosed conditions among U.S. physicians and affects
women more often than men.
Other authors from Cedars-Sinai include Sandy Park, B.A., Yuthana
Kong M.P.H. and Robert Wade. Sunanda V. Kane from the University of
Chicago also participated in the study.
Rifaximin is made by Salix Pharmaceuticals, Inc. Funding for the
study was provided by Salix Pharmaceuticals, Inc.
One of only five hospitals in California whose nurses have been
honored with the prestigious Magnet designation, Cedars-Sinai
Medical Center is one of the largest nonprofit academic medical
centers in the Western United States. For 17 consecutive years, it
has been named Los Angeles' most preferred hospital for all health
needs in an independent survey of area residents. Cedars-Sinai is
internationally renowned for its diagnostic and treatment
capabilities and its broad spectrum of programs and services, as
well as breakthroughs in biomedical research and superlative medical
education. It ranks among the top 10 non-university hospitals in the
nation for its research activities and was recently fully accredited
by the Association for the Accreditation of Human Research
Protection Programs, Inc. (AAHRPP).