Randomized double‐blind placebo‐controlled study to evaluate the effect of long‐acting mesalamine on postinfectious irritable bowel syndrome with diarrhea.

Background: A subset of patients with irritable bowel syndrome (IBS) develop their symptoms after gastroenteritis, referred to as postinfectious IBS (PI‐IBS). PI‐IBS is associated with low‐grade intestinal inflammation. Previous studies have evaluated mesalamine, an anti‐inflammatory drug, in patients with IBS. We evaluated the efficacy of long‐acting mesalamine in patients with PI‐IBS. Methods: Sixty‐one patients who developed diarrhea‐predominant IBS (IBS‐D) after gastroenteritis were randomized to receive either 2.4 g of long‐acting mesalamine or placebo daily for 8‐weeks. The symptoms assessed were abdominal pain, bloating, stool frequency, stool consistency, severity of diarrhea and constipation, satisfaction with bowel habits, and IBS affecting or interfering with life. Quality‐of‐life (QOL) was assessed using the IBS‐QOL questionnaire. The prespecified primary outcome variable was the overall bowel symptom score (BSS) after 8‐weeks of treatment. Effect sizes were expressed as standardized mean differences (Cohen's d). Results: Fifty‐four patients completed the 8‐week treatment (n = 28 mesalamine, n = 26 placebo), 49 (91%) were male, and age range 23–71 years (mean ± SD 43 ± 13). Mesalamine demonstrated superior efficacy compared to placebo on the primary outcome variable, overall BSS (Cohen's d = 0.57, p = 0.042). Mesalamine was also superior for the secondary outcome of how much IBS affects your life in general (d = 0.72, p = 0.01). For the secondary outcomes of IBS symptoms, 7 of the 7 symptoms had trends of mesalamine superiority. For the secondary outcomes of IBS‐QOL subscales, 8 of 9 had trends of mesalamine superiority. Conclusion: In patients with PI‐IBS, long‐acting mesalamine demonstrated to be effective in reducing IBS symptoms and improving QOL. [ABSTRACT FROM AUTHOR]