This study will evaluate the safety and effectiveness of the investigational drug DDP733 in treating female patients with IBS-c. A placebo control will be utilized.

Inclusion Criteria:

• Female from 18 to 65 years of age, inclusive

• Patient experiences recurrent abdominal pain or discomfort at least 3 days per month for the last 3 months with symptom onset at least 6 months prior to diagnosis. The patient's symptoms must be associated with 1 or more of the following:

  • Improvement with defecation
  • Onset associated with a change in frequency of stool
  • Onset associated with a change in form (appearance) of stool

• Negative serum and urine pregnancy tests

• Completion of at least six days of daily diary assessments using a phone-in information system prior to randomization

Exclusion Criteria:

• Serious underlying diseases, including psychiatric disorders
• Current history of conditions affecting bowel transit
• Recent history of biochemical or structural abnormalities of the gastrointestinal tract, gastrointestinal surgery, or gastrointestinal infection
• Clinically significant abnormal examination findings or laboratory tests
• Inability to stop taking certain medications, or a planned change in medications (including herbal remedies) which could interfere with study assessments
• Use of drugs and or ethanol which may interfere with compliance of study procedures or influence study outcome
• Presence of a medical condition which could interfere with the interpretation of study data
• Significant use of nicotine or caffeine