Ondansetron for the Treatment of IBS With Diarrhoea (IBS-D)

Irritable bowel syndrome is a common condition affecting 1 in 10 of the population. About a third of these suffer from diarrhoea, which severely impairs their quality of life. Previous studies in Nottingham have suggested that some patients with diarrhoea may have an excess of a chemical called serotonin in their gut. Serotonin stimulates secretion and propulsion in the gut and contributes to diarrhoea. We are interested to see whether a drug, Ondansetron, which blocks the effect of serotonin, would improve symptoms in patients with IBS and diarrhoea. We think the drug may work better in people with a specific gene type so your genetic makeup may be of influence and we would like to test this. Because IBS symptoms fluctuate, one way to determine whether Ondansetron is effective is to perform a randomised placebo controlled trial in which neither the patient nor the doctor knows which medication is being taken in each part of the study.