Therapeutic approach to the patient with irritable bowel syndrome

This article reviews briefly the evidence to support current therapies in irritable bowel syndrome (IBS) and the novel therapeutic approaches on the threshold of clinical application. Fiber is indicated at a dose of at least 12 grams per day in patients with constipation-predominant IBS. Loperamide (and probably other opioid agonists) are of proven benefit in diarrhea-predominant IBS; loperamide may also aid continence by enhancing resting anal tone, but there is no evidence that it results in pain relief. In general, smooth muscle relaxants are best used sparingly, on an as-needed basis, because their overall efficacy is unclear. The 5-HT3 antagonist, alosetron, results in adequate relief of pain and improvements in bowel function in female nonconstipated patients with IBS. Psychotropic agents are important in relieving depression and are of proven benefit for pain and diarrhea in patients with depression associated with IBS. Further trials with selective serotonin reuptake inhibitors are awaited. Psychological treatments including hypnotherapy are less widely available but may play an important role in the relief of pain. In summary, current therapies targeted on the predominant symptoms in IBS are moderately successful. As the bowel sensorimotor and limbic system disturbances of IBS are more clearly understood, we should anticipate other pharmacologic approaches in the near future, including alpha-adrenergic agonists and 5-HT4 agonists. New therapies directed at treatment of the syndrome, rather than relief of symptoms, are needed.