title: Plasma theophylline and caffeine and plasma clearance of theophylline during theophylline treatment in the first year of life.
abstract: Plasma concentrations of caffeine and theophylline were simultaneously determined in 17 preterm infants after oral administration of aminophylline for treatment of apnoea. The ratio of caffeine/theophylline concentration in plasma increased during the first 2 weeks of treatment, owing to the longer time required for caffeine than for theophylline to reach steady state. The caffeine/theophylline ratio at steady state was 0.57 +/- 0.03 (mean +/- SE). Thus, caffeine contributed significantly to the total methylxanthine load in the infants. The plasma clearance of theophylline was calculated from the plasma steady state concentrations. In 3 preterm infants treated with oral aminophylline, repeated sampling showed an approximately linear increase in clearance with time from 16.8 +/- 0.4 (mean +/- SE) at a postnatal age of 6-11 days to 30.9 +/- 2.5 ml/kg/h at 64-69 days. In 1 full-term infant treated with oral theophylline from 3.5 to 11.5 months of age, the plasma clearance of theophylline increased in a roughly linear manner, reaching a plateau of about 100 ml/kg/h at 6-7 months of age. This corresponds to the clearance found in 1-4 year old infants.
mesh_terms: D001049:Apnea / Q000097:blood / Q000188:drug therapy*; D002110:Caffeine / Q000097:blood*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007235:Infant, Premature, Diseases / Q000097:blood* / Q000188:drug therapy; D013806:Theophylline / Q000097:blood* / Q000627:therapeutic use; D014970:Xanthines / Q000097:blood
chemical_list: D014970:Xanthines; D002110:Caffeine; D013806:Theophylline