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

Multicenter, Randomized, Double-Blind, Placebo-Controlled Study to Assess The Efficacy and Safety of Three Different Doses (275, 550 AND 1100 MG) of Rifaximin Administered BID For Either Two or Four Weeks in The Treatment of Patients With Diarrhea-Associated Irritable Bowel Syndrome