Treating Traveler's Diarrhea: Rifaximin

Although there are many causes of infectious diarrhea that affects travelers, “traveler’s diarrhea” (TD) is generally considered to be caused predominately by the bacteria Escherichia coli (E. coli), as well as sometimes by Shigella species, Campylobacter jejuni, Salmonella species, and a few other bacteria. A number of antibiotics are prescribed to treat TD, with the most common being ciprofloxacin (Cipro).

In 2001 in the journal Clinical Infectious Diseases volume 33, pages 1807-1815, Dr. Herbert DuPont and his coauthors reported the results of a study that compared rifaximin (now marketed as Xifaxan) to ciprofloxacin for the treatment of TD. Paraphrasing the abstract that preceded the full study report, 187 adult subjects including students from the U.S. in Mexico or international tourists in Jamaica received (in a random fashion, so as not to bias the results) either rifaximin (400 mg by mouth twice a day) or ciprofloxacin (500 mg by mouth twice a day) for 3 days. The results indicated that the two antibiotics were equivalent in their effect with respect to clinical improvement within the first 24 hours, failure to respond to treatment, cure, and adverse events (which were low and similar in each group). The investigators reached the conclusion that rifaximin is a safe and effective alternative to ciprofloxacin for treatment of TD.

Rifaximin is a poorly-absorbed antibiotic, which means that the drug remains in the gastrointestinal (GI) tract of the person who consumes it, and has its beneficial effect by eradicating the bacteria within the GI tract that cause diarrhea without the antibiotic being absorbed to any significant degree into the bloodstream. According to Dr. Robert Steffen, this may be very important from a number of perspectives. First, the drug appears potent and well tolerated for treating TD. Since it is not absorbed, it would not be expected to be effective against other infections, such as urinary tract or respiratory, where absorption is important. Used selectively against TD, rifaximin might allow ciprofloxacin and other similar drugs of the fluoroquinolone class to be reserved for other infections and thus used with less frequency, which might lower the incidence of the development of bacteria resistant to this very important class of drugs. More work needs to be done to prove that a poorly-absorbed drug like rifaximin is safe in pregnant women and children, which would make therapy easier.

The manufacturer (Salix Pharmaceuticals, Inc.) expresses the following safety considerations: Rifaximin is indicated for the treatment of patients (greater than or equal to 12 years of age) with traveler’s diarrhea caused by noninvasive strains of Escherichia coli. It should not be used in patients with diarrhea complicated by fever or blood in the stool or diarrhea due to infectious agents other than E. coli. It should be discontinued if diarrhea symptoms worsen or persist for more than 24 to 48 hours, at which time alternative antibiotic therapy should be considered. The drug is not approved for use in pregnancy.