Conjugation and excretion of the amino and acetamido benzoic acids.

Abstract

The conjugation of the aminobenzoic acids with glycine and glucuronic acid has been measured in the rabbit and the dog. In both species the total conjugation is greatest with the ortho isomer, least with the para. In the rabbit, the amount of hippurate formed is greater than the amount of glucuronide formed, and in each case, greatest with the ortho isomer and least with the para. These relations are determined by the comparative first-order reaction rates, the comparative zero-order reaction rates, the concentration of the aminobenzoic acid in the body at which the reaction changes from first-order to zero-order, and the dose. In the dog, the meta aminobenzoic acid forms more hippurate than glucuronide, as in the rabbit, but for the ortho and para isomers the formation of hippurate is much less than that of glucuronide. The meta and para acetamidobenzoates are conjugated to a smaller extent than are the aminobenzoates. Slices of kidney and liver perform these conjugations to an extent agreeing with that in the whole animal, in some but not all cases. It appears that both species form the three hippurates in the kidney, but in the liver by the rabbit only. Both species form the three glucuronides, probably in both kidney and liver.