Oral Sustained Delivery of Theophylline Floating Matrix Tablets- Formulation and In-vitro Evaluation

The aim of the study was to develop and physicochemicaly characterize single unit controlled delivery system of Theophylline and was formulated as floating matrix tablet by direct compression method using gas generating agent (sodium bicarbonate) and various viscosity grades of hydrophilic polymers (HPMC K15M, K4M; HPC and Carbapol 934P). Formulation was optimized on the basis of buoyancy and in vitro drug release profile. Also tablets were tested for various tests like hardness, thickness, weight variation, friability, swelling index and erosion index. The tablets swelled and eroded upon contact with release medium (0.1 N HCl) at 37 C. The release rate could efficiently be modified by varying the matrix forming polymer, the use of polymer blends and the addition of water soluble or water insoluble fillers (such as dicalcium phosphate, lactose or mannitol). Fitting the in-vitro drug release data to Korsmeyer equation indicated that diffusion along with erosion could be the mechanism of drug release.