Our genetics service has been consulted several times recently about whether or not nitrogen scavenging agents typically used in urea cycle disorders would be useful in individuals with hepatic encephalopathy (HE) due to liver failure, i.e. from cirrhosis. Our a priori reasoning was that these scavenging agents may not be as effective in HE because they rely on alternative functioning pathways of the liver. However, Rockey et al, (Hepatology 2013, Jul 11) recently published a randomized, double-blind, placebo-controlled phase 2 trial showing the potential benefits of glycerol phenylbutyrate (GPB) in 178 patients with cirrhosis. They found that glycerol phenylbutyrate reduced hepatic encephalopathy events as well as ammonia in patients with cirrhosis with a good safety profile. This article provides evidence to consider using these nitrogen scavenging agents in hyperammonemia due to causes other than urea cycle defects.
Hilary Vernon, MD PhD