[Analysis of the theophylline pharmacokinetics of sustained-release theophylline (Theodur) dry syrup in children].

Sustained-release theophylline (Theodur) drysyrup was administered to 23 children aged 3-8 years and its pharmacokinetics were analyzed. Blood was drawn 9 times during 24 hours for serum theophylline concentrations after reaching to the steady state. Results were as follows: (1) All of 9 serum theophylline concentrations were between 5-15 micrograms/ml among 20 children. (2) Serum theophylline concentrations were higher than 15 micrograms/ml in three children. Two of them showed decreased clearance and body weight of the other was significantly heavier than the average weight for her height. (3) VdTD and theophylline clearance each showed 0.77-0.88 L/kg and 0.070-0.091 L/kg/hr. (4) Tmax was 2.9-3.5 hours and T1/2 was 7.1-8.8 hours. (5) There were no significant differences in pharmacokinetics paramaters between each age group. Therefore, sustained-release theophylline (Theodur) drysyrup 16 mg/kg/day seems to be reasonable dose for 3-8 years but monitoring of serum theophylline concentrations is advisable if possible.