Title: L-carnitine in Hyperammonemia and Hepatic Encephalopathy
Abstract: L-carnitine is suggested as a potential therapeutic agent in metabolic encephalopathies, such as ammonia-precipitated hepatic encephalopathy (HE). In humans, ammonia is produced mainly by the metabolism of proteins and amino acids. Most of the ammonia is detoxified by the urea cycle which is located in the liver. Thus, disturbances of the urea cycle in the liver lead to higher ammonia levels in blood. In humans, hyperammonemia (HA) arises mainly from liver diseases and is in most cases associated with HE. There are currently only a few therapeutic strategies, and outcome expectations for patients with HE are poor. Lcarnitine and its acyl-derivates are suggested as potential and low-cost therapeutic agents. In animal models, L-carnitine has been shown to counteract neurotoxic effects of ammonia, increase energy metabolism and decrease mortality. A protective effect against ammoniaprecipitated HE has also been observed in cirrhotic patients. A review of the literature offers in vitro and in vivo studies, as well as human trials with promising results. This chapter provides a comprehensive summary and a summarized discussion of the literature data concerning the effects of L-carnitine, with special emphasis on hyperammonemic syndromes and HE.