The FDA has approved Viberzi (eluxadoline) and Xifaxan (rifaximin), two new treatments, manufactured by two different companies, for irritable bowel syndrome with diarrhea (IBS-D) in adult men and women. Studies estimate that IBS affects 10 to 15 percent of adults in the United States.
According to the National Institutes of Health, patients with irritable bowel syndrome (IBS) experience a number of signs and symptoms, including pain or discomfort in the abdomen and changes in bowel movement patterns. IBS-D is a subtype characterized mainly by loose or watery stools at least 25 percent of the time.
“For some people, IBS can be quite disabling, and no one medication works for all patients suffering from this gastrointestinal disorder,” said Julie Beitz, M.D., director of the Office of Drug Evaluation III in the FDA’s Center for Drug Evaluation and Research. “The approval of two new therapies underscores the FDA’s commitment to providing additional treatment options for IBS patients and their doctors.”
Viberzi, which contains a new active ingredient, is taken orally twice daily with food. Viberzi activates receptors in the nervous system that can lessen bowel contractions. Viberzi is intended to treat adults with IBS-D.
Xifaxan can be taken orally three times a day for 14 days, for the treatment of abdominal pain and diarrhea in patients with IBS-D. Patients who experience a recurrence of symptoms can be retreated with a 14 day treatment course, up to two times. Xifaxan, an antibiotic derived from rifampin, was previously approved as treatment for travelers’ diarrhea caused by E. coli and for reduction of the risk in adult patients of recurring overt hepatic encephalopathy, the changes in brain function that occur when the liver is unable to remove toxins from the blood. The exact mechanism of action of Xifaxan for treatment of IBS-D is not known, but is thought to be related to changes in the bacterial content in the gastrointestinal tract.
The most common side effects in patients treated with Viberzi include constipation, nausea, and abdominal pain. The most serious known risk associated with Viberzi is the risk of spasm in the sphincter of Oddi, the smooth muscle that surrounds the end portion of the common bile and pancreatic ducts, which can result in pancreatitis. Viberzi should not be used in patients with a history of bile duct obstruction, pancreatitis, severe liver impairment, or severe constipation, and in patients who drink more than three alcoholic beverages per day.
The most common side effects in patients treated with Xifaxan for IBS-D include nausea and an increase in alanine aminotransferase (ALT), a liver enzyme measured in blood. If diarrhea does not improve or worsens after treatment with Xifaxan, then evaluation for development of a severe infectious diarrhea, C. difficile enterocolitis, should be performed. Caution should be used when using Xifaxan in patients with severe liver impairment or when combined with certain other drugs.
See the FDA Announcement
See also Medical Law Perspectives, May 2013 Report: Drugs, Dosage, and Damage: Physician Liability for Prescribing or Administering Medication
See also Medical Law Perspectives, July 2012 Report: Foodborne Illness: When Grabbing a Bite Can Be Deadly