Regulatory

U.S. FDA OKs drug for hepatic encephalopathy

Last Updated: 2010-03-24 19:59:00 -0400 (Reuters Health)

By Deena Beasley

LOS ANGELES (Reuters) - The U.S. Food and Drug Administration today approved the use of Salix Pharmaceuticals' antibiotic Xifaxan (rifaximin) antibiotic as a treatment for reducing the risk of recurrent hepatic encephalopathy in adults.

Rifaximin is already approved by the FDA for so-called travelers' diarrhea caused by certain strains of E. coli bacteria.

A pivotal trial of rifaximin, reported online today in the New England Journal of Medicine, showed that it cut the risk of recurrent hepatic encephalopathy by more than half. The article also said the drug reduced the risk of hospitalization.

Lead author Dr. Nathan M. Bass, from the University of California, San Francisco and colleagues, randomly assigned 299 patients who were in remission from recurrent hepatic encephalopathy to receive either rifaximin, 550 mg twice daily, or placebo for 6 months.

Rifaximin significantly reduced the risk of an episode of hepatic encephalopathy, as compared with placebo (hazard ratio, 0.42; p < 0.001). A breakthrough episode of encephalopathy occurred in 22.1% of the rifaximin group versus 45.9% of the placebo group. Hepatic encephalopathy required hospitalization in 13.6% of the patients in the rifaximin group and in 22.6% of patients in the placebo group (HR, 0.50; p = 0.01).

More than 90% of patients in the study also received lactulose therapy. The incidence of adverse events was similar in the two groups, as was the incidence of serious adverse events.

The U.S. Food and Drug Administration previously granted orphan status to rifaximin for treating hepatic encephalopathy. The designation comes with a seven-year marketing exclusivity period.

Salix expects 550 mg tablets of the drug to be available by the end of May.

Other antibiotics used to treat hepatic encephalopathy are not recommended for prolonged treatment -- even though they can also reduce the number of ammonia-producing bacteria in the gut -- because of possible side effects. Rifaximin tends to stay in the intestine and not be absorbed by the body.

N Engl J Med 2010; 362:1071-1081.