- Males and non-pregnant, non-breastfeeding females with established diagnosis of IBS-D by modified Rome III criteria (Abdominal Pain Intensity: weekly average of worst daily score of >3.0 on a 0 to 10 point scale and Stool Consistency: at least one stool with a consistency of Type 5, 6 or 7 Bristol stool score on at least 2 days per week)