Duloxetine in the treatment of irritable bowel syndrome: an open-label pilot study.

To assess the efficacy of duloxetine for irritable bowel syndrome (IBS). We conducted an open-label 12-week trial of duloxetine 60 mg daily in 15 patients with IBS without concurrent major depressive disorder. The primary outcome measure was average abdominal pain. Secondary measures included IBS symptoms, Clinical Global Impression-Severity, Hamilton Anxiety Rating Scale, IBS Quality-of-Life Scale, and Sheehan Disability Scale. We analyzed changes using random regression and one-sample t-tests. Fourteen patients completed at least one post-baseline evaluation; eight completed the study. Duloxetine was associated with significant improvement (p < 0.05) in pain, severity of illness, quality of life, loose stool, work and family disability, and anxiety. However, duloxetine did not improve hard stool. Although we found no evidence of serious duloxetine toxicity, seven participants withdrew over the course of the study because of adverse drug events. In this small, open-label study, duloxetine appeared to be effective for many features of IBS, but its adverse effects, most notably constipation, limited its use. Since our study excluded individuals with concurrent major depression, it appears that duloxetine may benefit IBS independently of its antidepressant effects. These encouraging but preliminary open-label findings support further investigation of duloxetine treatment in placebo-controlled trials of IBS.