FDA: The U.S. Food and Drug Administration today 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. 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. Studies estimate that IBS affects 10 to 15
percent of adults in the United States. 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
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 safety and effectiveness of Viberzi for treatment of IBS-D were
established in two double-blind, placebo-controlled clinical trials in
which 2,425 patients were randomly assigned to receive Viberzi or
placebo. Results showed Viberzi was more effective in simultaneously
reducing abdominal pain and improving stool consistency than placebo
over 26 weeks of treatment.
The safety and effectiveness of Xifaxan for treatment of IBS-D were
established in three double-blind, placebo-controlled trials. In the
first two trials, 1,258 patients were randomly assigned to receive
Xifaxan or placebo for 14 days, and then followed for a 10-week
treatment-free period. More Xifaxan-treated patients reported
improvements in abdominal pain and stool consistency than those on
placebo. A third trial evaluated repeat courses of Xifaxan, because
patients with IBS-D can develop recurrent signs and symptoms after a
single treatment course of Xifaxan. A total of 636 patients with
recurrence were randomized to receive either Xifaxan or placebo for two
additional 14-day courses separated by 10 weeks. More patients treated
with Xifaxan than placebo were responders in abdominal pain and stool
consistency in this phase of the study.
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.
Viberzi is manufactured by Patheon Pharmaceuticals, Inc. based in
Cincinnati, Ohio and distributed by Forest Pharmaceuticals, Inc. a
subsidiary of Forest Laboratories, LLC, based in Cincinnati, Ohio.
Xifaxan is marketed by Salix Pharmaceuticals, Inc. based in Raleigh, North Carolina.