Biotransformation and Pharmacokinetics of Salicylate in Newborn Animals

Abstract

SUMMARY Plasma half-lives and urinary metabolites were examined in pups, kids, pigs, and a foal after intravenous administration of sodium salicylate (44 mg./kg.). Each subject was studied at 1 day of age and periodically to 30 days. The plasma half-lives of salicylate decreased as a function of age. By 30 days, the plasma half-lives were similar to those in adults of the same species. Apparent specific volumes of distribution decreased during the same period. Unchanged salicylate, salicylurate, and salicyl glucuronide were observed in chromatograms of urine of kids and the foal. Salicylate, salicylurate, gentisate, salicyl glucuronide, and an unidentified metabolite (R f value of 0.12) were isolated from the urine of newborn pups and pigs. The percentage of urinary salicyl glucuronide increased with age; that of the unidentified metabolite (R f value of 0.12) decreased. The compound with R f value of 0.12 was believed to be the same salicyl metabolite which was isolated from the urine of adult cats in a previous study.