ORLANDO, Fla.--(BUSINESS WIRE)--Salix Pharmaceuticals, Ltd. (NASDAQ:SLXP) today announced findings from two analyses of a Phase II clinical trial that demonstrate the utility of rifaximin, a non–absorbed, gut–selective antibiotic, in the treatment of patients with diarrhea–predominant irritable bowel syndrome (IBS). Data presented at the annual meeting of the American College of Gastroenterology (ACG) showed that patients treated with rifaximin demonstrated that the severity of baseline IBS symptoms of abdominal pain and bloating predicted clinical response to rifaximin and demonstrated statistically greater clinical improvement in quality of life compared with placebo.