Irritable Bowel Syndrome Remains a Difficult Condition to Manage

Nicholas J. Talley, MD, PhD

In This Article

Antidiarrheal Drugs

Opioid agonists reduce intestinal secretion and increase fluid and electrolyte absorption, in part because of prolongation of intestinal transit time. The only primarily antidiarrheal drug that has been studied in IBS is loperamide. In 4 randomized controlled trials comparing active drug versus placebo, while diarrhea convincingly improved, abdominal pain or bloating did not.[3,23,24,25,26] The quality of the 3 trials considered by the ACG Task Force was intermediate ( Table 3 ).[3] Overall, there is reasonably good evidence that loperamide does improve IBS-associated diarrhea but not other symptoms. Hence, this drug needs to be used in combination with other therapy to control the IBS symptom complex adequately in many cases.

Diphenoxylate, a derivative of pethidine, also has opioid activity and is available in combination with atropine.[1,2] There are no randomized controlled trials of this agent in IBS with diarrhea, although anecdotally it appears to be useful. Codeine phosphate is also an antidiarrheal drug with analgesic properties, but its use should be avoided because of the high risk of dependence.[1,2] For a small subset of patients with IBS who may have bile-salt malabsorption, a bile-salt–sequestering agent, such as cholestyramine, seems to be clinically useful.[1] However, no randomized controlled trials of the use of bile-salt–sequestering agents in IBS are available.


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