The authors compare the effect of lactulose, neomycin, and an association of these two drugs on fasting arterial blood ammonia levels and the arterial blood ammonia level induced by oral ammonium acetate in nine bed-rested patients with chronic portal systemic encephalopathy. Lactulose and neomycin brought about a similar decrease in blood ammonia level or improvement in ammonia tolerance, but the combination of lactulose and neomycin produced a result significantly greater than either drug alone. The enhanced effectiveness of this association may presumably be explained by addition of the respective effects of lactulose and of neomycin on the intracolic concentration of diffusible ammonia (NH₃), the depletion of which lowers the basal arterial ammonemia and reduces the ammonia load peak value by enhancing diffusion of blood ammonia to the colonic lumen.

No abstract