MAUI, HAWAII – , according to IBS expert Lin Chang, MD, a professor and vice chief of the division of digestive diseases at the University of California, Los Angeles.
Dr. Lin Chang
Rifaximin is an antibiotic that works in the intestines but is not absorbed by the body, and is approved for irritable bowel syndrome with diarrhea (IBS-D). It’s a second-line option for moderate illness when diet, OTC medications, and other easier options don’t do the trick. Endpoints were met by about 10% more patients on rifaximin than placebo in randomized trials, perhaps by resetting gut microbiota.
“It was a small therapeutic gain, but it was statistically significant,” Dr. Chang said at the Gastroenterology Updates, IBD, Liver Disease Conference. In her own practice, she said it sometimes helps even with bloating and abdominal distension, two of the most vexing problems in IBS-D.
However, symptoms come back after 3-6 months, and prices approach $2,000 for the 2-week IBS-D course. Insurance doesn’t always fully cover it, and the Food and Drug Administration has capped treatments at three.
That’s left providers wondering what to do when people ask for rifaximin after seeing it advertised and eager for some way to predict if it will work or not. Some clinicians have turned to a breath test for small-intestinal bacterial overgrowth (SIBO) before prescribing rifaximin because there is evidence that SIBO contributes to IBS-D, but others have not. It’s a contentious issue in IBS medicine, Dr. Chang said.
A recent open-label study funded by rifaximin maker Salix Pharmaceuticals made a case for testing. Among 93 IBS-D patients, 60% with a positive breath test at baseline had reduced pain, diarrhea, and other symptoms after 550 mg three times daily for 2 weeks, versus 26% with a negative test (Am J Gastroenterol. 2019 Dec;114[12]:1886-93).
Even so, when asked after her IBS presentation, Dr. Chang said she doesn’t breath test because it doesn’t make sense. Even with positive results, “you don’t really know if they have SIBO or not. Sometimes healthy controls have a positive test, and some people with IBS who end up responding to rifaximin have a negative breath test. It’s up to you, [but] it doesn’t correlate” with outcomes, she said.
Indeed, a letter in response to the study made a strong case that nine of the subjects should have been counted as having a negative, not positive, breath test, and if they had, the difference in outcome would have disappeared (Am J Gastroenterol. 2020 Mar 2. doi: 10.14309/ajg.0000000000000569).
Dr. Chang has opted for an empiric approach. “I just treat patients who meet the criteria used in the clinical trials,” such as moderate abdominal pain and bloating, she said (for example, N Engl J Med. 2011 Jan 6;364[1]:22-32).
And she doesn’t push if people can’t afford rifaximin. Some turn to other antibiotics, like metronidazole (Flagyl) or ciprofloxacin (Cipro), which are absorbed in the GI tract, but Dr. Chang said symptoms will recur after a few months regardless of the antibiotic. “You don’t want all these young women to be given antibiotics over and over again. Their symptoms are just going to come back, and you are going to have to learn how to treat them anyway,” she said.
Instead, she moves on to other options when patients are at the point where they need prescription pharmaceuticals. One of her top choices is the tricyclic antidepressant amitriptyline. It helps with the pain; the anticholinergic effects counter the diarrhea; and the sedative effects help patients who have a hard time sleeping. Sleep problems make IBS-D symptoms worse, Dr. Chang said.