In vivo evaluation of a theophylline oral controlled-release unit dosage form.

A 200 mg controlled-release unit dosage form which was designed and developed showed desired in vitro release characteristics. This dosage form was subjected to in vivo studies (single and multiple p.o. dosing) in Beagle dogs with the aim of insuring the desired controlled-release performance in a biologic system. Using a parallel study design (intravenous, p.o. solution, p.o. controlled-release standard and p.o. controlled-release test dosage form), the dosage form index (DI), the fraction of drug absorbed (absolute bioavailability) (f) and the extent of (relative) bioavailability (EBA) of the experimental dosage form were determined.