LOS ANGELES — A combination of rifaximin and loperamide, taken at the first sign of traveler's diarrhea, is the optimal way to treat an illness that affects 10 million American tourists a year, Dr. Herbert L. DuPont said at the annual Digestive Disease Week.
Rifaximin, a gut-selective antibiotic, and loperamide, an antimotility agent, were tested alone and in combination in a randomized trial of 315 U.S. college students who developed acute diarrhea and at least one symptom of an enteric infection while studying in Mexico.
“The Imodium [loperamide] immediately stopped the diarrhea and the antibiotic cured the disease,” Dr. DuPont said in an interview during the meeting.
“If they took Imodium alone, they got immediate improvement, but then they continued to be sick. Rifaximin by itself was slow to get going, but it cured the disease after 24–30 hours,” he said.
“The combination zapped the thing rapidly and cured it, so we think it's probably the optimal way to manage traveler's diarrhea,” said Dr. DuPont, professor of medicine and epidemiology at the University of Texas, Houston, and chief of internal medicine at St. Luke's Episcopal Hospital, also in Houston.
The participants were assigned to receive either 200 mg of rifaximin three times daily for 3 days; 4 mg of loperamide initially, followed by 2 mg after each unformed stool, not to exceed 8 mg/day for 48 hours; or both of these regimens simultaneously.
During the 5-day study period, more than 75% of the students receiving rifaximin or the drug combination achieved a clinical cure, compared with 58% of those receiving loperamide alone.
The time from initiation of treatment to the passage of the last unformed stool was also shorter in patients taking the drug combination (27.3 hours) or rifaximin alone (32.5 hours) than with loperamide alone (69 hours), he reported.
Loperamide and the drug combination resulted in significantly fewer stools passed in the first 24 hours, but in the case of loperamide alone, the effect was transient.
Abdominal cramps were less frequent in patients taking the rifaximin-loperamide combination.
Finally, the participants' assessment of “complete wellness” was higher with rifaximin and the rifaximin-loperamide combination. All of the treatments were well tolerated.
In the poster presentation, Dr. DuPont concluded that the drug combination “provides clinically relevant benefits vs. either agent alone, providing more rapid symptom relief and clinical cure… [possibly representing] a new standard of care.”
Loperamide is available over the counter, and rifaximin is FDA approved for traveler's diarrhea. Salix Pharmaceuticals Inc., maker of rifaximin, provided funding for the study.