Study to Assess the Efficacy and Safety of Rifaximin Administered BID in the Treatment of Patients With Diarrhea-Associated Irritable Bowel Syndrome
Study to Assess the Efficacy and Safety of Rifaximin Administered BID in the Treatment of Patients With Diarrhea-Associated Irritable Bowel Syndrome
This is placebo-controlled study of three rifaximin doses in patients with DIBS. Subjects
 will be randomized to receive daily doses of placebo BID, rifaximin 275 mg BID, rifaximin 550
 mg BID, or 1100 mg BID for 14 days. These four groups will subsequently receive an additional
 two weeks of placebo for a total of 4 weeks of treatment. A fifth group of subjects will
 receive rifaximin 550 mg BID for a period of 28 days. Subjects who successfully respond to
 treatment at the end of the 28-day Treatment Phase will be followed in a Post-treatment Phase
 that includes study visits during Weeks 6, 8, 12 and 16. Subjects who relapse during the
 Post-treatment Phase will be discontinued from the study.
While IBS is one of the most common chronic medical conditions the etiology of IBS is
 unknown. Although not a life-threatening illness, IBS is considered to be a serious condition
 that has a substantial impact on a subject's day-to-day function. IBS is characterized by
 abdominal pain and altered bowel habits, including diarrhea, constipation, or alternating
 diarrhea and constipation. Symptoms are typically intermittent but may be continuous.
Inclusion Criteria:

 1. Male or female subject 18 years of age or older.

 2. Irritable bowel syndrome confirmed by the Rome II Criteria

 3. Lower endoscopic examination that demonstrates normal colonic anatomy

 Exclusion Criteria:

 1. Subject has exclusively constipation-predominant IBS (CIBS) that is characterized by <
 3 bowel movements/week or hard and lumpy stools.

 2. Subject has alternating IBS, but is currently presenting with constipation associated
 IBS symptoms.

 3. Subject has had adequate control of their DIBS and their symptom of bloating the week
 preceding the screening visit or at the time of randomization. Bloating includes the
 following symptoms: abdominal fullness, bloating, gas, or swelling.

 4. Subjects has a positive stool culture for O & P (ovum and parasite) and/or Clostridium
 difficile

 5. Subject has failed to record 2 negative weekly global assessments during the past 10
 days prior to randomization.