A Phase 2, Multi-center Study to Evaluate the Efficacy and Safety of ONO-2952 in Female Subjects With Diarrhea-Predominant Irritable Bowel Syndrome (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:

1. Improvement with defecation

2. Onset associated with a change in frequency of stool/defecation

3. 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 Crohn'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