Comparison of [14C] Phenacetin and Amino[14C]pyrine Breath Tests after Acute and Chronic Liver Injury in the Rat

Abstract

The elimination of both [14C]phenacetin and amino[14C]pyrine as judged by production of 14CO2 in the breath showed a linear response relationship to the degree of hepatic necrosis. There was a differential sensitivity of the elimination of these test compounds to acute and chronic liver injury, suggesting a variable susceptibility of the enzymes responsible for their metabolism. Elimination rate constant is more important than half-life when comparing the effect of liver injury on drug metabolism. Breath tests will reflect the extent of hepatic damage and may also be used to examine the effect of liver disease on various routes of drug metabolism.