title: Caffeine metabolism in the newborn.
abstract: The concentrations of caffeine and metabolites in urine have been examined as a function of age to explore the remarkably slow elimination of caffeine by human infants. Urine samples were obtained from 3 adults and 10 infants aged 8 days to 8 months during therapeutic treatment with caffeine. A high-performance liquid chromatographic (HPLC) procedure involving reversed-phase partition chromatography was developed to separate caffeine and 13 of its metabolites. During the first month of life, caffeine accounted for more than 85% of the identifiable products in urine. Caffeine remained the predominant component for the first 3 months, but its percentage decreased gradually to the adult value of less than 2% by the age of 7 to 9 months. This change reflected increasing metabolite production, not decreasing urinary caffeine concentration. The adult metabolite pattern of partially demethylated xanthines and urates was attained by 7 to 9 months. The data indicate that the 4-day plasma t1/2 of caffeine characteristic of the newborn depends in large part on slow urinary excretion of unchanged drug since there is little or no metabolism. Subsequent decrease in the t1/2 to about 4 hr by the age of 8 months correlates closely with the rise in metabolite production.
mesh_terms: D000328:Adult; D000375:Aging; D001711:Biotransformation; D002110:Caffeine / Q000378:metabolism* / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D013997:Time Factors; D014527:Uric Acid / Q000652:urine; D014970:Xanthines / Q000652:urine
chemical_list: D014970:Xanthines; D014527:Uric Acid; D002110:Caffeine