Robert Levy, MD Jason Corbo, PharmD, BCPS Shailendra Prasad, MBBS, MPH North Memorial Family Medicine Residency, University of Minnesota, Minneapolis (Drs. Levy and Prasad); Family Medicine Residency Program, UPMC St. Margaret, Pittsburgh, Pa (Dr. Corbo)
PURLs EDITOR Bernard Ewigman, MD, MSPH Department of Family Medicine, The University of Chicago
Patients whose diarrhea was more severe at baseline didn’t respond as well to ondansetron as did those whose diarrhea was less severe. The only frequent adverse effect was constipation, which occurred in 9% of patients receiving ondansetron and 2% of those on placebo.
WHAT’S NEW: Another option for IBS patients with diarrhea
A prior, smaller study of ondansetron that used a lower dosage (12 mg/d) suggested benefit in IBS-D.14 In that study, ondansetron decreased diarrhea and functional dyspepsia. The study by Garsed et al1 is the first large RCT to show significantly improved stool consistency, less frequent defecation, and less urgency and bloating from using ondansetron to treat IBS-D.
CAVEATS: Ondansetron doesn’t appear to reduce pain
In Garsed et al,1 patients who received ondansetron did not experience relief from pain, which is one of the main complaints of IBS. However, this study did find slight improvement in formed stools, symptom relief that approached—but did not quite reach—clinical significance, fewer days with urgency and bloating, and less frequent defecation. This study did not evaluate the long-term effects of ondansetron use. However, ondansetron has been used for other indications for more than 25 years and has been reported to have a low risk of adverse effects.15
CHALLENGES TO IMPLEMENTATION: Remember ondansetron is not for IBS patients with constipation
Proper use of this drug among patients with IBS is key. The primary benefits of ondansetron are limited to IBS patients who suffer from diarrhea, and not constipation. Ondansetron should not be prescribed to IBS patients who experience constipation, or those with mixed symptoms.
ACKNOWLEDGEMENT The PURLs Surveillance System was supported in part by Grant Number UL1RR024999 from the National Center For Research Resources, a Clinical Translational Science Award to the University of Chicago. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Center For Research Resources or the National Institutes of Health.