Management of hepatic encephalopathy: focus on antibiotic therapy.

Hepatic encephalopathy (HE) is a major neuropsychiatric complication of both acute and chronic liver failure. Symptoms of HE include attention deficits, alterations of sleep patterns and muscular incoordination progressing to stupor and coma. The pathogenesis of HE is still unknown, although ammonia-induced alterations of cerebral neurotransmitter balance, especially at the astrocyte-neurone interface, may play a major role. Treatment of HE is therefore directed at reducing the production and absorption of gut-derived neurotoxic substances, especially ammonia. The non-absorbable disaccharides lactulose and lactitol were long considered as a first-line pharmacological treatment of HE, but a recent systematic review questioned their efficacy, pointing out that there is insufficient high-quality evidence to support their use. Oral antibiotics are regarded as a suitable therapeutic alternative. However, the prolonged use of antimicrobials is precluded by the possible occurrence of adverse events. Rifaximin, a synthetic antibiotic structurally related to rifamycin, displays a wide spectrum of antibacterial activity against Gram-negative and Gram-positive bacteria, both aerobic and anaerobic, and a very low rate of systemic absorption. Available evidence suggests that rifaximin - thanks to its efficacy and remarkable safety - has the highest benefit-risk ratio in the overall treatment of HE.