The present invention provides a new simple polymeric matrix tablet that delivers highly soluble drugs over long periods of time and is easy to manufacture. More specifically, the drug is first granulated with or encapsulated in a swellable polymer, such as a gum, to form a granule. This granule is disposed in a matrix of a more swellable, erodible polymer, such as HPMC or Polyethyleneoxide, and optionally includes pectin. The more swellable erodible polymer has a diffusion rate coefficient which is greater than the diffusion rate coefficient of the relatively less swellable polymer. It is this difference in diffusion rate coefficients between the first and second polymers which controls the rate of drug release and allows the system to approach zero order drug delivery over the drug release period. Other advantages which the present invention holds over existing systems including ease of manufacturing and reproducibility of release profiles under well defined hydrodynamic conditions. The delivery system of the present invention has a potential to maximally release its drug content in a controlled manner over a long time period while achieving complete dissolution.