[Adaptation of the oral dosage of theophylline to the asthmatic child. Value of a kinetic test by the intravenous route]

Abstract

The authors propose a practical method for determining chronic oral theophylline dosage in children from slow intravenous theophylline infusion (45 minutes). Calculated clearances and half lifes provided a basis for daily oral theophylline doses and dosing intervals. Pharmacokinetic characteristics (mean +/- SD) in 34 asthmatic children (age range 2-14 years) averaged 0.082 +/- 0.028 l/kg/h for Cl; 0.436 +/- 0.087 l/kg for Vd; 4.07 +/- 1.43 h for t 1/2. Calculated daily dosages necessary to maintain mean serum theophylline concentration of 12.5 mg/l ranged from 9.6 to 40.9 mg/kg/d (average 24.5 mg/kg/d). The validity of proposed dosage schedules is studied in 11 children (among the 34 patients) undergoing a chronic theophylline treatment either with rapid absorption products, or sustained-release form. The difference between predicted and effective serum concentrations was within +/- 1.8 mg/l in all cases.