Abstract
The objective of the present study was to develop and evaluate a pulsatile system of theophylline based on chronopharmaceutical considerations. The basic design consists of an impermeable capsule body, which contains the drug and is closed by an erodible tablet plug. The body portion of the hard gelatin capsules was cross-linked by the combined effect of formaldehyde and heat treatment. The formulation variables such as type of plug material, capsule content, different plug composition, plug weight and plug hardness was investigated to characterize the lag time (t10).The results indicated that drug release from the pulsatile capsule exhibited an initial lag period, followed by a stage of rapid drug release. For the complete and rapid drug release from the capsule body, 15% of effervescent agent had to be included in the capsule content. The lag time criterion of 5 hrs Was satisfied by the tablet plug containing 16%HPMC K100LV. A good correlation was observed between erodible tablet weight and lag time.