Pharmacokinetics of delayed (DR) versus sustained release (SR) theophylline formulations following single (SD) and repetitive dosing (RD).

The present study compares the pharmacokinetic characteristics of equivalent theophylline doses of a delayed release formulation of oxtriphylline and a sustained release formulation given as single or six hourly repetitive dosings in six adult asthmatics. Both formulations maintained serum theophylline levels within therapeutic range for eight hours following six hourly repetitive dosings. The same dose of theophylline given as a single dose or after reaching steady states does not produce comparable serum levels. Effective and safe theophylline therapy in the management of chronic asthma not only requires frequent monitoring of serum theophylline levels but also requires clear understanding of the formulation used, the time and the clinical condition under which sampling is done.