Randomized Placebo Controlled Efficacy And Safety Study Investigating GW876008 In Patients With Irritable Bowel Syndrome

• Changes in wkly adequate relief [ Time Frame: wks 1-6, period 1 & wks 9-15, period 2 ]
• Proportion of subjects with adequate relief of IBS pain & discomfort [ Time Frame: on all 4 of the last 4 wks of the treatment phase in period 1 & 2 ]
• IBS GIS: [ Time Frame: weekly ]
• IBSQoL: [ Time Frame: day 1,wks 6, 9, 15, 19 ]

• Proportion of subjects with adequate relief of IBS pain & discomfort on all 4 of the last 4 wks of the treatment phase in period 1 & 2
• Changes in wkly adequate relief wks 1-6, period 1 & wks 9-15, period 2
• IBS GIS:wkly
• IBSQoL:day 1,wks 6, 9, 15, 19

• IBS composite symptom score: [ Time Frame: weekly ]
• Changes in somatizer score (PHQ-15): [ Time Frame: day 1 and weeks 3, 6, 9, 12, 15 and 19 ]
• Changes in anxiety and/or depression: [ Time Frame: day 1 and weeks 3, 6, 9, 12, 15 and 19. ]

• IBS composite symptom score: weekly
• Changes in somatizer score (PHQ-15):day 1 and weeks 3, 6, 9, 12, 15 and 19
• Changes in anxiety and/or depression: day 1 and weeks 3, 6, 9, 12, 15 and 19.

This is a double-blind, placebo-controlled, randomised crossover study to investigate the efficacy and safety of GW876008

Inclusion Criteria:

• The subject has been diagnosed with IBS consistent with the Rome II Criteria as adapted in Appendix 3 of the protocol
• The subject has normal results from a flexible sigmoidoscopy, colonoscopy, or a flexible sigmoidoscopy plus barium enema, according to subject's age, within 5 years of randomization. Otherwise, the appropriate procedure(s) must be performed and normal results obtained during the 7-day procedure window (prior to randomization):

If the subject is < 50 years of age and has not had a colonic examination within 5 years of the Screening Visit, flexible sigmoidoscopy, or colonoscopy must be performed.

If the subject is = 50 years of age and has not had a colonic examination within 5 years of the Screening Visit, a colonoscopy or flexible sigmoidoscopy plus barium enema must be performed.

• Colonic procedure results must be known prior to randomization into the study and dispensing study medication
• During the two-week screening phase, the subject must have conducted self assessments on = 10 days of 14 day (with 80% compliance on daily IVRS calls) compliance assessment using the telephone data entry system

Exclusion Criteria:

• As a result of any of the medical interview, physical examination, evaluation of mental state and psychiatric history or screening investigations the physician
• Subject reported no stool for 7 consecutive days during the two-week screening phase responsible considers the subject unfit for the study
• The subject has a concurrent illness or disability that may affect the interpretation of clinical data, or otherwise contraindicates participation in this clinical study (e.g., an unstable cardiovascular, autoimmune, renal, hepatic, pulmonary, endocrine, metabolic, gastrointestinal, haematological, or neurological condition).