The study was terminated due to slow accrual of subjects.

The objective is to evaluate whether ONO-2952 modulates visceral pain perception produced by rectal distention in female patients with IBS-D

Inclusion Criteria:

1. Female 18-65 years of age (inclusive)

2. Diagnosed with IBS based on the following criteria (Rome III criteria):

   • Symptom onset at least 6 months prior to diagnosis, and
   • Recurrent abdominal pain or discomfort at least 3 days per month for the past 3 months, and
   • Abdominal discomfort or pain associated with two or more of the following at least 25% of the time:
   • improvement with defecation
   • onset associated with a change in frequency of stool/defecation
   • onset associated with a change in form (appearance) of stool

3. Diagnosed with IBS-D, defined as loose/watery stools ≥ 25% and hard/lumpy stools ≤ 25% of defecations

Exclusion Criteria:

• Any structural abnormality of the gastrointestinal (GI) tract (other than esophagitis or gastritis)
• History of Chron's disease, ulcerative colitis, diabetes mellitus, lactose malabsorption, malabsorption syndromes, celiac sprue, or any upper GI symptoms that may impact the assessment of IBS symptoms