Review article: new receptor targets for medical therapy in irritable bowel syndrome.
BACKGROUND
Despite setbacks to the approval of new medications for the treatment of irritable bowel syndrome, interim guidelines on endpoints for irritable bowel syndrome (IBS) trials have enhanced interest as new targets for medical therapy are proposed based on novel mechanisms or chemical entities.


OBJECTIVE
To review the approved lubiprostone, two targets that are not meeting expectations (tachykinins and corticotrophin-releasing hormone), the efficacy and safety of new 5-HT(4) agonists, intestinal secretagogues (chloride channel activators, and guanylate cyclase-C agonists), bile acid modulation, anti-inflammatory agents and visceral analgesics.


METHODS
Review of selected articles based on PubMed search and clinically relevant information on mechanism of action, safety, pharmacodynamics and efficacy.


RESULTS
The spectrum of peripheral targets of medical therapy addresses chiefly the bowel dysfunction of IBS and these effects are associated with pain relief. The pivotal mechanisms responsible for the abdominal pain or visceral sensation in IBS are unknown. The new 5-HT(4) agonists are more specific than older agents and show cardiovascular safety to date. Secretory agents have high specificity, low bioavailability and high efficacy. The potential risks of agents 'borrowed' from other indications (such as hyperlipidaemia, inflammatory bowel disease or somatic pain) deserve further study.


CONCLUSIONS
There is reason for optimism in medical treatment of IBS with a spectrum of agents to treat bowel dysfunction. However, visceral analgesic treatments are still suboptimal.
Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), College of Medicine, Mayo Clinic, Rochester, MN 55905, USA. camilleri.michael@mayo.edu
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D000527:Alprostadil / Q000031:analogs & derivatives* / Q000627:therapeutic use; D001646:Bile / Q000187:drug effects* / Q000378:metabolism; D005769:Gastrointestinal Motility / Q000187:drug effects*; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000188:drug therapy*; D000068238:Lubiprostone; D011788:Quality of Life; D044406:Receptors, Serotonin, 5-HT3 / Q000627:therapeutic use*; D017366:Serotonin Receptor Agonists / Q000627:therapeutic use*; D016896:Treatment Outcome
D044406:Receptors, Serotonin, 5-HT3; D017366:Serotonin Receptor Agonists; D000068238:Lubiprostone; D000527:Alprostadil