Treatment of irritable bowel syndrome

Irritable bowel syndrome is characterised by diverse symptoms including abdominal pain, altered bowel function (increased bowel frequency, constipation), bloating, abdominal distension, the sensation of incomplete evacuation, and the increased passage of mucus. No unifying hypothesis explains all these symptoms, and no single agent will alleviate all components of the symptom complex. The currently favoured model to explain the symptoms includes central and end organ components. These may be combined into an integrated hypothesis that incorporates psychological factors (stress, distress, affective disorder) and dysfunction of the gut (disorders of motility, visceral hypersensitivity). Current standard drug treatment generally entails a symptom directed approach with drugs aimed at pain, constipation, and diarrhoea. Development of new drugs has focused mainly on agents that modify the effects of 5-hydroxytryptamine (5-HT) in the gut. Alternatives to this single receptor approach exist, although not all patients respond to educational and psychological interventions, and treatment with drugs will remain an option for non-responders.