Pharmacokinetic aspects of theophylline in premature newborns

• Published in: The New England journal of medicine Vol. 295; no. 8; p. 413
• Main Authors: Aranda, J V, Sitar, D S, Parsons, W D, Loughnan, P M, Neims, A H
• Format: Journal Article
• Language: English
• Published: United States 19.08.1976
• Subjects: Adult; Apnea - drug therapy; Blood Proteins - metabolism; Child; Humans; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases - drug therapy; Protein Binding; Theophylline - administration & dosage; Theophylline - blood; Theophylline - therapeutic use; Time Factors
• ISSN: 0028-4793
• DOI: 10.1056/NEJM197608192950803

To characterize further the pharmacokinetics of theophylline in premature infants, its concentraion in blood was measured by high-pressure liquid chromatography after intravenous infusion given to six apneic premature newborns three to 15 days of age. Theophylline's apparent volume of distribution was 0.690 +/- 0.095 liters per kilogram (mean +/- S.E.), a value similar to that of children, but the half-life (30.2 +/- 6.5 hours) was nine times longer. Blood clearance rate (17.6 +/- 2.3 ml per kilogram per hour) was lower than plasma clearance rate (100 ml per kilogram per hour) of young children. At a total plasma concentration of 17 mg per liter, 56.4 +/- 3.8 and 36.4 +/- 3.8 per cent of the theophylline was bound to adult or full-term cord plasma proteins, respectively. Bilirubin and theophylline did not compete for plasma protein. Calculations suggest that a loading doses of 5.5 mg per kilogram and a maintenance dose rate of 1.1 mg per kilogram per eight hours would achieve and maintain a mean blood concentration of 8 mg per liter (about 10 mg per liter in plasma).