Effect of rifaximin and paromomycin in the treatment of portal-systemic encephalopathy

Abstract

Portal-systemic encephalopathy, a condition caused by liver failure, often complicates hepatic cirrhosis. Its pathogenesis is unknown, although hyperammonemia is thought to play an important role. Non-absorbable antibiotics have been used to treat hepatic encephalopathy because of their ability to reduce intestinal flora and thereby decrease the intestinal production of ammonia. We compared the effectiveness of rifaximin, a new non-absorbable antibiotic, with that of paromomycin. Thirty cirrhotic patients (20 men and 10 women, aged 39 to 75 years) suffering from portal-systemic encephalopathy with hyperammonemia were selected by Conn's grading. Fifteen patients were randomly assigned to treatment with paromomycin (1,500 mg/day), and the other 15 received rifaximin (1,200 mg/day) for 10 days. Before, after 5 days, and after 10 days of treatment, we evaluated blood ammonia levels and each patient's signs and symptoms according to Conn's grading. Baseline ammonia levels and the degree of hepatic encephalopathy were positively correlated ( r = .65; P < 0.001). A significant decrease in blood ammonia levels ( P < 0.001) and in the signs and symptoms of hepatic encephalopathy ( P < 0.05) was observed in both groups after 5 and 10 days of therapy. The highly significant positive correlation between ammonia levels and degree of hepatic encephalopathy suggests the usefulness of non-absorbable antibiotic therapy in lowering blood ammonia levels. Rifaximin proved to be as effective as paromomycin even though baseline ammonia levels were higher in the rifaximin group. Because of its minimal absorption and a wide antibacterial activity, rifaximin should be considered the non-absorbable antibiotic of choice in the treatment of portal-systemic encephalopathy.