A Study to Evaluate Efficacy of YM060 on Diarrhea-predominant Irritable Bowel Syndrome (D-IBS) in Female Patients

Inclusion Criteria: * Patients meeting the Rome III Diagnostic Criteria * Loose (mushy) or watery stools within the last 3 months * Abdominal discomfort and/or pain during their non-menstrual period Exclusion Criteria: * Patients with a history of surgical resection of the stomach, small intestine or large intestine * Patients with a history or current diagnosis of inflammatory bowel disease (Crohn's disease or colitis ulcerative) * Patients with a history or current diagnosis of colitis ischemic * Patients with a current diagnosis of enteritis infectious * Patients with a current diagnosis of hyperthyroidism or hypothyroidism * Patients who are currently participating in another clinical trial (including a post-marketing clinical study) or those who participated in another clinical trial (including a post-marketing clinical study) within 12 weeks before the study * Patients with a history or current diagnosis of malignant tumor * Patients with a history of abuse of drugs or alcohol within 1 year or those who are currently abusing them