The risk of ischaemic colitis in irritable bowel syndrome patients treated with serotonergic therapies.

Ischaemic colitis (IC) is the most common form of ischaemic injury to the gastrointestinal (GI) tract. IC typically presents with the sudden onset of lower abdominal pain, cramping and rectal bleeding, and is usually self-limited with low morbidity, although it may cause gangrenous or fulminant colitis, especially when the right colon is involved. Multiple medical conditions, as well as several pharmacological agents, are associated with IC, including irritable bowel syndrome (IBS) and drugs used for its treatment that act on gut serotonin 5-HT receptors. These include the selective 5-HT3 receptor antagonist alosetron, currently approved for the treatment of severe diarrhoea-predominant IBS in women who fail to respond to conventional treatment, and cilansetron, another 5-HT3 receptor antagonist that is no longer in clinical development. In addition, the 5-HT4 receptor partial agonist tegaserod, which was approved for the treatment of constipation-predominant IBS in women, was associated with IC in the postmarketing setting, as was renzapride, a 5-HT4 agonist/5-HT3 antagonist.