Study to Assess the Efficacy and Safety of Rifaximin Administered BID in the Treatment of Patients With Diarrhea-Associated Irritable Bowel Syndrome

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.