Eluxadoline is manufactured by Patheon Pharmaceuticals Inc., Cincinnati, Ohio, and distributed by Forest Pharmaceuticals Inc., a subsidiary of Forest Laboratories, LLC, Cincinnati. Rifaximin is marketed by Salix Pharmaceuticals, Inc., Raleigh, N.C.
Studies estimate that IBS affects up to 15 percent of adults in the United States. IBS-D is known as a subtype with diarrhea occurring a quarter of time or more.
“For some people, IBS can be quite disabling, and no one medication works for all patients suffering from this gastrointestinal disorder,” said Julie Beitz, MD, 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.”
Eluxadoline is an oral agent with a new active ingredient. Patients should be instructed to take the medicine twice daily with food. Eluxadoline activates receptors in the nervous system that can lessen bowel contractions.
Rifaximin, another oral medication, can be taken three times a day for 14 days, for the treatment of abdominal pain and diarrhea in individuals with IBS-D. Patients who experience recurrent symptoms can be retreated with a 14-day treatment course, up to two times.
An antibiotic derived from rifampin, rifaximin 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 exact mechanism of action of rifaximin 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 eluxadoline for treatment of IBS-D were established in two double-blind, placebo-controlled clinical trials in which more than 2,400 patients were randomly assigned to receive eluxadoline or placebo. Results showed eluxadoline was more effective in simultaneously reducing abdominal pain and improving stool consistency than placebo over 26 weeks of treatment.
The safety and effectiveness of rifaximin was established in three double-blind, placebo-controlled trials. In the first two trials, more than 1,250 patients were randomly assigned to receive rifaximin or placebo for 14 days, and then followed for a 10-week treatment-free period. More rifaximin-treated patients reported improvements in abdominal pain and stool consistency than those in the placebo group.
A third trial evaluated repeat courses of rifaximin, because patients with IBS-D can develop recurrent signs and symptoms after a single treatment course of rifaximin. A total of 636 patients with recurrent symptoms of IBS-D were randomized to receive either rifaximin or placebo for two additional 14-day courses separated by 10 weeks. More patients treated with rifaximin than placebo noted relief in abdominal pain and better stool consistency in this phase of the study.