Plasma theophylline concentrations and airway function in asthmatic children receiving standard and modified RTC...

The effects of three different dosage schedules for sustained-release theophylline (Theolong) were investigated in children with asthma. With regimen II (unequal doses at 0800 h and 2000 h), the maximum plasma theophylline concentration following the evening dose was significantly higher than that following the morning dose, and also was larger than that following the evening dose with regimen I (equal doses at 0800 and 2000 h). With regimen III (equal doses at 0600 h and 2100 h), the mean theophylline concentration-time curve showed a single large peak at 1100 h, whereas with regimen I, there were two peaks at 2300 and at 1400 h. Knowledge that a change of the dosage schedule can affect the pharmacokinetics of theophylline in this way should aid physicians in its safe and effective use.