A Study of 3 Doses of Dextofisopam in Females With Irritable Bowel Syndrome

This is a double-blind, randomized , placebo-controlled Phase 2b study of the safety, tolerability, and efficacy of 100, 200 and 300 mg BID dextofisopam in female patients suffering from diarrhea-predominant or alternating-Irritable Bowel Syndrome. (d-IBS or a-IBS.) Approximately 120 patients will be enrolled in each of the 4 arms of the study which will be conducted in up to 70 clinical sites in the USA. The patients will; be stratified by diagnosis. Outpatient females, 18 to 65 years old will be enrolled in the study if diagnosed with d-IBS or a-IBS after having been screened during up to 17 days prior to enrollment (including colonoscopy if not done within the last 5 years) and found to have no organic disease that might have caused their complaints of abdominal pain or discomfort which when started was associated with a change in stool frequency or form and/or improves with defecation. Patients will be instructed to take 3 capsules of the blinded study drug twice a day by mouth and to record by an interactive voice response system (IVRS ) any change in their symptoms. Patients who meet all the Inclusion and Exclusion criteria will be evaluated at baseline (one day prior to taking study drug ) including laboratory determinations including a pregnancy test for women of childbearing potential, vital signs, electrocardiogram ( ECG), recording of adverse events(AE's) and filling out the IBS Quality of Life Questionnaire( IBSQOL ), the Work Productivity and Activity Impairment Questionnaire-IBS Version ( WPAI:IBS )and the Hospital l Anxiety and Depression Questionnaire ( HAD). Enrolled patients will have 12 weeks of double-blind treatment followed by a 28 day post treatment period. Symptoms will be recorded daily . Patients will visit the investigating site at weeks 4, 8 and 12 after the baseline visit and the procedures performed at baseline will be repeated A post treatment visit will occur 28 days after discontinuing study drug. Vital signs, AE's, concomitant medications and daily and weekly symptom assessment via IVRS will be recorded.