Irritable bowel syndrome (IBS) affects around 10% of the population and accounts for 1.8 million consultations/year in primary care in England and Wales (0.6 million patients). Around one third of patients meet the criteria for IBS with diarrhoea (IBS-D) and despite its high prevalence, there is no satisfactory treatment at present. Loperamide is currently used to reduce bowel frequency, however it does not improve symptoms such abdominal pain.~Other symptoms of IBS-D include frequent, loose, or watery stools with associated urgency, which can severely limit socialising, travelling, and eating out, resulting in a reduced quality of life and work productivity.~The primary aim of the study is to determine the effectiveness and safety of the use of ondansetron in patients with the symptoms of IBS-D including urgency, looseness of stool, frequency of defecation and abdominal discomfort. Ondansetron belongs to a class of drug known as 5HT3RA's and a recent meta-analysis shows that 5HT3RAs is an effective treatment for IBS-D, improving stool consistency and reducing frequency and urgency of defecation.~400 patients with IBS-D will be randomised on a 1:1 basis to receive either Ondansetron or Placebo. Both treatments will be administered in oral doses of between 4-24mg daily for 12 weeks. Dose titration will be undertaken in the first two weeks of the study to avoid constipation.~The primary outcome of response will be assessed at 12 weeks post randomisation using patient reported data on daily stool frequency and abdominal pain.~If ondansetron is effective in the trial, it could easily be widely adopted since it is an inexpensive, safe, and generic drug. By providing an effective treatment, it could not only reduce patient symptoms, but also reduce costs of repeated referral and investigation.
A placebo controlled study to determine the efficacy and mode of action of ondansetron in the treatment of irritable bowel syndrome with diarrhoea.