Theophylline metabolism during the first month of life and development

Abstract

The metabolic pathway of theophylline (T) was studied in 12 newborns, one young infant, six children, and three adult volunteers. T was injected IV, and blood and urine samples were assayed for T, caffeine (C), and their metabolites by a high-pressure liquid chromatography technique. We confirmed the methylation of T to C in newborn infants but not in older subjects. Demethylation of T to 3-methylxanthine was found in the young infant, in children, and in adults, but not in newborns. The major products excreted by neonates were T, 1-methyluric acid, and 1,3-dimethyluric acid. Children excreted a larger fraction of methyluric acids than adults. Renal and body clearance of T and C are reported and discussed in relation to the age.