A Study of the Safety and Effectiveness of DDP733 in Treating IBS With Constipation in Females

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