Review Compares Drug Options for Irritable Bowel Syndrome

Significant number needed to harm for tricyclic antidepressants and alosetron versus rifaximin

TUESDAY, March 27 (HealthDay News) -- Tricyclic antidepressants and alosetron are associated with significant harm in treating irritable bowel syndrome (IBS) compared with rifaximin, and selective serotonin reuptake inhibitors (SSRIs) and lubiprostone appear to be safe, according to a meta-analysis published in the April issue of The American Journal of Medicine.

Eric Shah, M.B.A., of the Texas Tech University Health Sciences Center in Lubbock, and colleagues conducted a literature review (1950 to April 2011) to identify studies of IBS treatments. The number needed to harm was determined based on the relative risk of experiencing an adverse event requiring discontinuation of treatment, and the number and severity of adverse events were recorded.

The researchers identified 26 clinical trials, including eight with alosetron, six with tricyclic antidepressants, five with rifaximin, four with SSRIs, and three with lubiprostone. In one combined phase III trial, lubiprostone was found to be safe, with insignificant harm. There were not enough data on SSRIs for a reliable meta-analysis of harm, but they appeared to be safe. Based on more rigorous data, the numbers needed to harm for tricyclic antidepressants, alosetron, and rifaximin were 18.3, 19.4, and 8,971, respectively, and the numbers needed to treat were 8, 7.5, and 10.6, respectively. For every 2.3 and 2.6 patients who benefited from tricyclic antidepressants and alosetron, respectively, there was an adverse event resulting in discontinuation of the study drug, whereas the number for rifaximin was 846 patients.

"We found that rifaximin and lubiprostone have the lowest level of harmful side effects of all the well-studied drug therapies for IBS," a coauthor said in a statement. "This underscores the need for us to continue to monitor new therapies for this disease. While it is important to see benefit with drugs, harm is something we do not often assess well."

Two authors disclosed financial ties to pharmaceutical companies, many of which manufacture drugs used to treat IBS. Cedars-Sinai Medical Center, the affiliation for two of the authors, has a licensing agreement with Salix Pharmaceuticals, which manufactures rifaximin.

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