Big headlines regarding IBS last week as major news outlets picked up the story of a new study on Xifaxan as a treatment for IBS. Although the study results were positive, (hooray!), to me the headlines were misleading in that they implied that IBS can now be cured with a two week trial of this particular antibiotic. Let's look at the background behind the study and the details of the study itself:
Xifaxan (rifaximin) is an antibiotic that has been used by researchers who have looked at small intestine bacteria overgrowth (SIBO) as a possible contributing cause for IBS. Xifaxan is not absorbed in the stomach and thus is thought to be available to act upon bacteria in the large and small intestine. Because of promising results in terms of testing the SIBO theory, the medication is now undergoing clinical trials for FDA approval as a treatment for IBS without constipation. This new study was undertaken and sponsored by the pharmaceutical manufacturer as part of the FDA approval process.
As for the current study, the number of participants was sizable, with 1260 patients enrolled and a total of 90 percent completing the entire study. All patients suffered IBS without constipation. Patients were randomly assigned to receive 550 mg of Xifaxan three times a day or a placebo for a total of two weeks. Data was collected regarding IBS symptoms for an additional ten weeks.
The results showed that Xifaxan was significantly more likely than placebo to result in patient report of "adequate relief" of IBS symptoms, bloating, and abdominal pain. This symptom alleviation was seen to have held through the ten weeks following the administration of the meds. Side effects were minimal and similar for both the treatment group and the placebo group.
Now for the problem with the headlines. A close look at the numbers shows that the numbers of individuals who experienced symptom relief with the medication were not all that much higher than those who recieved a placebo. Forgive my rounding of the numbers, but the percentage of individuals who benefited from Xifaxan was about 40 to 50 percent for all assessed symptoms, while about 30 percent of placebo patients experienced symptom relief for all assessed symptoms. As you can see, Xifaxan does offer a viable treatment for some patients - just not all patients!
Please know that I am glad to hear that Xifaxan can help some patients - we all know that such help is sorely needed. I just worry about hopelessness kicking in for those who do not experience the miraculous results implied by the news media. IBS appears to have many causes, therefore for many people, a variety of treatment strategies will be needed.
In case you are interested, I have been blogging about the approval process for Xifaxan:
- Clinical Trial for IBS-D (Thursday July 10, 2008)
- Digestive Disease Week 2010 (Monday May 10, 2010)
- FDA Approval Sought for Rifaximin (Saturday June 12, 2010)
- Xifaxan for Non Constipation IBS
- Gut Bacteria and IBS
- Small Intestine Bacterial Overgrowth
- Book Review: "A New IBS Solution"
Pimental, M., et.al. "Rifaximin Therapy for Patients with Irritable Bowel Syndrome without Constipation" New England Journal of Medicine 2011 364:22-32.
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