Branched-chain amino acids vs lactulose in the treatment of hepatic coma: a controlled study.

A controlled study was carried out in two groups of 20 patients with cirrhosis of the liver and deep coma in order to compare the efficacy of intravenous branched-chain amino acid solutions in 20% glucose (group A) vs lactulose plus glucose in isocaloric amount (group B). There were 3 drop-outs from each group. Plasma amino acids and ammonia were assayed at fixed intervals throughout the 10-day observation period. Routine tests were assayed daily. Complete mental recovery was obtained in 70% of patients in group A and in 47% in group B. The difference was not significant, likely due to the lack of placebo group. With the exception of free tryptophan/all competing amino acids ratio, the modifications in plasma amino acid levels showed no correlation with the clinical course under either treatment. Ammonia, like free tryptophan, decreased significantly upon mental recovery, paralleling the clinical course throughout the study. In conclusion, branched-chain amino acids are at least as effective as lactulose in deep hepatic coma. It is suggested that branched-chain amino acids may reverse coma either by competing with brain entry of the aromatic amino acid or by metabolically decreasing free tryptophan and ammonia.