A Study to Evaluate the Effect of ASP0456 in Patients With Constipation Predominant Irritable Bowel Syndrome

This study is a multicenter, double-blind, placebo-controlled, parallel-group, comparative study to investigate dose-responses of efficacy, safety, and pharmacokinetics of ASP0456 in patients with constipation-predominant irritable bowel syndrome (IBS-C) according to the Rome III Diagnostic Criteria (2006 revised edition, established by the Rome III Committee) after oral administration of ASP0456.

Inclusion criteria

• Patients who had abdominal pain or discomfort repeatedly for at least 3 days per month during the 3 months before screening examination associated with at least 2 out of the following 3 conditions: (1) Improvement with defecation; (2) Onset associated with a change in frequency of stool; and (3) Onset associated with a change in form (appearance) of stool, and had the above symptom (IBS symptom) 6 months or more before the screening examination period.
• Patients with ≥25% of stools hard or lumpy (with each bowel movement occurring without antidiarrheal, laxative, suppository or enema) and <25% of them loose (mushy) or watery during the 3 months before the screening examination.
• Patients who had pancolonoscopy or contrast enema (or sigmoidoscopy) after the onset of IBS symptom and had no organic changes.

Exclusion criteria

• Patients with a history of surgical resection of the stomach, gallbladder, small intestine or large intestine
• Patients with other concurrent diseases that may affect the digestive tract passage or large intestinal function
• Patients with other concurrent diseases that may affect the assessment of abdominal pain/discomfort
• Patients with blood pressure, pulse rate, clinical laboratory test, or 12-lead ECG at the time of screening examination that was rated as Grade 2 or greater on the "Severity Criteria for Drug Adverse Reaction" and judged to be clinically significant