Earlier this week, on May 27, 2015, the U.S. Food and Drug Administration approved two new medications, eluxadoline (to be known by the brand name Viberzi) and rifaximin (known by the brand name Xifaxan) for use in treating irritable bowel syndrome with diarrhea in adults, 18 and older, both men and women. Both medications have met the FDA’s safety and effectiveness standards and reduced symptoms of IBS-D for subsets of study volunteers in multiple large, double-blind, placebo controlled clinical trials. Neither Viberzi nor Xifaxan is approved for use in children, and there is no known information at this time regarding potential future availability in countries other than the United States.
Viberzi is an oral medication to be taken with food twice daily. It is a mixed opiod receptor agonist designed to lessen bowel contractions. There are several reported possible side effects and it is not appropriate for those with a history of bile duct obstruction, pancreatitis, severe liver impairment, severe constipation or those who consume more than three alcoholic drinks daily. As Virberzi is a narcotic, the FDA expects it to be classified as a controlled substance. It is manufactured by Panteon Pharmaceuticals and is to be distributed by Forest Laboratories. It is projected to be available for doctors to prescribe to patients by early 2016.
Xifaxan is an antibiotic that is not absorbed in the gut and is believed to change the bacterial composition of the gastrointestinal tract. It is meant to be taken by mouth three times daily for 14 days at a time. There are some risks of side effects, but it is generally considered safe, although it also should not be used by those with severe liver impairments or along with certain other medications. In addition, research shows an eventual relapse rate of almost two-thirds among volunteers in the most recent Xifaxan clinical trials. In those individuals for whom IBS-D symptoms return after use of Xifaxan, the FDA has deemed up to two 14 day periods of re-treatment appropriate.
This was second application for approval of Xifaxan for IBS-D. In 2011, the FDA denied the first request, citing concerns about the high relapse rate and requesting more studies. Xifaxan is currently available in the United States for other conditions, and has been prescribed “off label” for use in IBS-D by some physicians. While this practice is legal, this week’s official approval for use in IBS-D will allow Salix Pharmaceuticals to market the medication specifically for irritable bowel syndrome with diarrhea, thereby presumably increasing availability and awareness among physicians and people with IBS-D. Further details on this approval can be found at the reputable links below.
The original FDA press release about Virberzi and Xifaxan.
International Foundation for Functional Gastrointestinal Disorders (IFFGD) summary on Viberzi
IFFGD summary on Xifaxan
Lengthy, detailed article with sources, “New Meds OK’d for Hard-to-Treat IBS With Diarrhea” by Kathleen Doheny, WebMD Health News, May 28, 2015
As many in the IBS community are aware, FDA-approved prescription medications specifically for irritable bowel syndrome of any subtype are extremely limited, and no single treatment, whether it is medication, diet, psychological interventions, or others, proves appropriate or effective for every individual with IBS, even those with similar symptom patterns. The only prescription drug specifically for IBS with diarrhea, alosetron (Lotronex), was approved for use only in women with IBS-D in 2000 but was quickly withdrawn from the market within months due to reports of serious side effects including several deaths. According to The New York Times at the time, in 2002, after advocacy from the IBS community, Lotronex was reintroduced only under significant restrictions for use in those women with very severe IBS-D for whom no other treatments are effective. IBS Impact is pleased that those with diarrhea-predominant IBS will soon have two safer and more widely available options in Viberzi and Xifaxan, and hopes that research on these two medications and others in development will continue.
We urge those who are considering either Viberzi or Xifaxan to read the available information, to familiarize themselves with the benefits and risks and to consult their own doctors as to if either medication is worth trying in their specific situations. IBS Impact focuses on awareness and advocacy and does not endorse particular treatments, but does encourage accurate and up to date information from reputable sources so that individuals with IBS and their families can make the most informed choices for their own needs and desires.