Paroxetine to Treat Irritable Bowel Syndrome Not Responding to High-Fiber Diet: A Double-Blind, Placebo-Controlled Trial

OBJECTIVES The purpose of the trial was to determine whether a high-fiber diet (HFD) alone or in combination with paroxetine or placebo was effective treatment for patients with irritable bowel syndrome (IBS). METHODS Design: Trial of HFD alone (Group 1) followed by a randomized, double-blind trial of HFD with paroxetine or placebo (Group 2). Setting: Gastroenterology office in a 524-bed university-affiliated community hospital in Pittsburgh. Patients: Men and women, aged 18–65 yr, previously diagnosed with IBS but otherwise healthy. Intervention: Institution of HFD in 98 participants consuming low- or average-fiber diets. Allocation of paroxetine to 38 and placebo to 43 symptomatic participants consuming HFDs. Measurements: Overall well-being, abdominal pain, and abdominal bloating (Groups 1 and 2); food avoidance, work functioning, and social functioning (Group 2). RESULTS In Group 1, overall well-being improved in 26% patients, and abdominal pain and bloating decreased in 22% and 26% patients, respectively, with an HFD. In Group 2, overall well-being improved more with paroxetine than with placebo (63.3%vs 26.3%; p = 0.01), but abdominal pain, bloating, and social functioning did not. With paroxetine, food avoidance decreased (p = 0.03) and work functioning was marginally better (p = 0.08). Before unblinding, more paroxetine recipients than placebo recipients wanted to continue their study medication (84%vs 37%; p < 0.001). CONCLUSIONS The difference in overall well-being found in our paroxetine/placebo trial is greater than that found in previously published drug/placebo trials for IBS. Moreover, the difference in well-being applied to nondepressed recipients of paroxetine.