Pharmacokinetic aspects of caffeine in premature infants.

The pharmacokinetic profile of caffeine was studied in 15 premature infants. Five infants received a single intravenous dose of 10 mg/kg of caffeine citrate 100% at birth and on the 15th day of life. Ten neonates were studied during daily therapy with caffeine for prophylaxis of idiopathic apnea. The time course of plasma and urinary concentrations of caffeine and theophylline shows that caffeine is transformed to theophylline at birth, while total urinary xanthines decrease significantly (p less than 0.001) 72 h after the loading dose given on the 15th day of life. During the whole period of treatment, the decrease in total urinary xanthines and the constant urinary percentage elimination of theophylline are due to further metabolism of theophylline. We confirm that the intravenous loading dose of 10 mg/kg can rapidly obtain therapeutic blood levels of caffeine. We also confirm that the maintenance therapy can be carried out with a single daily dose.