IBS Drugs With Fewest Side Effects

Irritable bowel syndrome meds causing least harm identified by scientists

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) As many as one in five people have irritable bowel syndrome, a chronic disorder that can bring about abdominal pain, gas and bloating. Some IBS drugs, however, cause adverse reactions.

Along with dietary changes and stress management, patients with IBS may take medications to improve their symptoms.

Scientists recently analyzed common drug treatments for IBS and pinpointed two prevalent therapies as the best options with the fewest side effects.

"Ask your doctor about the right IBS treatment."

Mark Pimentel, MD, director of Cedars-Sinai's Gastrointestinal Motility Program in Los Angeles, and his colleagues evaluated 26 clinical trials of drug interventions deemed of merit by the American College of Gastroenterology.

The team examined three treatments for diarrhea—tricylic antidepressants, alosetron (Lotronex), and rifaximin (Xifaxa). They also reviewed constipation therapies—lubiprostone (Amitiza) and antidepressants called serotonin reuptake inhibitors (SSRIs).

"We found that rifaximin and lubiprostone have the lowest level of harmful side effects of all the well-studied drug therapies for IBS," said Dr. Pimentel.

In reviewing the clinical trials, researchers discovered that for every 846 patients aided by rifaximin, only one had to discontinue the medication. Those taking lubiprostone and SSRIs exhibited a complete lack of adverse reactions.

By contrast, for every 2.3 patients who benefited from tricyclic antidepressants, one suffered harmful side effects and had to stop taking the medication. For every 2.6 patients helped by alosetron, one had to halt that treatment. These side effects included nausea, insomnia, heart palpitations and a decreased appetite.

“Tricyclic antidepressants and alosetron are associated with significant harm in treating irritable bowel syndrome with diarrhea,” concluded researchers, “and clinicians should expect to have one adverse event for every three patients who benefit from therapy. Clinicians should be aware of harm when using pharmacotherapy for irritable bowel syndrome.”

Low doses of tricyclic antidepressants are commonly prescribed to treat IBS-related diarrhea, according to the National Institutes of Health.

Alosetron is a drug shown to slow the movement of stool in the gut. Lubiprostone promotes gut secretion. Rifaximin is an antibiotic prescribed for traveler's diarrhea.

Of the 26 clinical trials, four were with SSRIs, three were with lubiprostone, six were with tricyclic antidepressants, eight with alosetron, and five with rifaximin.

"The results underscore the need for us to continue to monitor new therapies for this disease," said Dr. Pimentel. "While it is important to see benefit with drugs, harm is something we do not often assess well."

This study was published in the April edition of the American Journal of Medicine. Besides Cedars-Sinai, other centers participating in the research included the School of Medicine at Texas Tech University's Health Sciences Center; the UCLA Department of Medicine; Beth Israel Deaconess Medical Center; and Harvard Medical School. Funding for the study was provided by the Beatrice and Samuel A. Seaver Foundation.

Dr. Pimentel discovered the use of rifaximin for IBS. Cedars-Sinai holds patent rights to the discovery and has a licensing agreement with Salix Pharmaceuticals Inc., which markets the drug. Dr. Pimentel is a consultant to Salix and serves on its scientific advisory board.

None of the authors is affiliated with lubiprostone maker Takeda Pharmaceuticals or other drugs that were evaluated.

Reviewed by: 
Review Date: 
July 25, 2012
Last Updated:
May 16, 2013