The purpose of the study is to investigate whether renzapride will help alleviate the symptoms associated with constipation predominant irritable bowel syndrome in female patients.

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder characterized by recurrent symptoms of abdominal pain/discomfort accompanied by disturbed bowel function.

In this study female patients with constipation predominant IBS will receive one of two dosing regimens of renzapride or placebo for 12 weeks. Patients will record the severity of their symptoms throughout the study. The results will be analysed to see if those patients who received renzapride had greater relief of their symptoms than did the patients who received placebo.

Inclusion Criteria:

• Females with constipation predominant IBS as defined by the Rome II criteria
• Colonoscopy or sigmoidoscopy in previous 5 years showed no significant disease

Exclusion Criteria:

• Patients who have diarrhoea predominant or alternating symptom IBS
• Other gastrointestinal diseases that affect bowel transit