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By Michael Smith ,
North American Correspondent,
MedPage TodayPublished: November 01, 2010Reviewed by Zalman S. Agus, MD; Emeritus Professor University of Pennsylvania School of Medicine andDorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
BOSTON -- In patients with minimal hepatic encephalopathy, an antibiotic appears to reverse difficulties in driving a car associated with the condition, a researcher said here.Rifaximin (Xifaxan) is most commonly used to treat travelers' diarrhea, but it is also approved for minimal hepatic encephalopathy, according to Jasmohan Bajaj, MD, of Virginia Commonwealth University Medical Center in Richmond, Va.In a randomized, placebo-controlled, double-blind trial, patients taking the drug did better on simulated driving tasks than those given placebo, Bajaj reported at the annual meeting of the American Association for the Study of Liver Diseases
Minimal encephalopathy does not lead to overt cognitive dysfunction, but can be shown to exist with neuropsychological tests. It impairs quality of life and has been shown to increase the risk of traffic accidents.
The importance of the study, Bajaj said, is that "it's the first time a cognitive change has resulted in a real-life outcome."
He and his colleagues enrolled 41 patients -- all current drivers -- with minimal hepatic encephalopathy confirmed by a battery of five cognitive tests.
At baseline, the patients were tested using a simulator for driving and navigation skills, with the outcomes being such things as collisions, speeding tickets, and illegal turns, Bajaj said. At the same time, they were given cognitive tests, quality of life was measured using the Sickness Impact Profile, venous ammonia levels were measured, and they were graded on the Model for End-Stage Liver Disease (MELD) score.
The patients were randomly assigned to get rifaximin (at 550 mg a day) or placebo for 30 days, at the end of which time they returned for adherence testing and were given another 30 days of study drug, Bajaj said.
At the end of the eight-week study period, the baseline tests were repeated, including those in the simulator. The primary outcomes were improvements in the driving measures -- speeding, illegal turns, and collisions. Changes in cognition and quality of life were secondary outcomes.
The researchers found:
76% of those getting the drug had fewer total driving errors, compared with 33% of those on placebo (P=0.013)
81% of those on the drug had fewer speeding tickets, compared with 33% of those on placebo (P=0.005)
62% of those on rifaximin had fewer illegal turns, compared with 19% of those on placebo (P=0.012)
There was no significant difference in the number of collisions
Participants on rifaximin also had a significantly better increase in cognition and on the psychosocial elements of the Sickness Impact Profile, Bajaj reported.
He said the goal was to increase insight into driving errors, which was best measured by such subtle factors as illegal turns and speeding tickets. In the simulator, he said, a collision stopped the game, with a loud crash, which allowed patients in both groups to gain the same insight.
"Tickets and illegal turns do not come with anything, so the patients have to themselves realize they've gone off," he said.
The findings are important because they appear to demonstrate that some of the cognitive effects of minimal hepatic encephalopathy can be turned back by medication, according to Kevin Mullen, MD, of MetroHealth Medical Center in Cleveland, who moderated the session at which the data were presented.
"Up to now, no one had ever shown reversibility of those driving problems," he told MedPage Today.
Other papers presented at the session, he noted, suggested that the drug could improve survival and slow progression of the disease. But those effects -- as well as the possible cognitive benefits -- are "still up in the air" and need more study.
The study was supported by the NIH and Salix.
Bajaj reported financial links with Salix and Ocera Therapeutics.
Mullen reported financial links with Salix, Ocera, Hyperion, Hoffman LaRoche, and CLDG.
Primary source: American Association for the Study of Liver DiseasesSource reference:Bajaj JS, et al "Rifaximin improves driving simulator performance in minimal hepatic encephalopathy: A double - blind, placebo - controlled, prospective randomized trial"
AASLD 2010; Abstract 22.
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