The design of an controlled drug delivery system should be primarily aimed at achieving more predictable and increased bioavailability of drugs. Over the years, novel dosage forms have become increasingly sophisticated with major role being played by controlled release drug delivery systems. Such systems release drug at predetermined rate, as determined by drug pharmacokinetics and desired therapeutic concentration. It is evident from the recent scientific and patent literature that an increased interest in novel dosage forms that are retained in the body for a prolonged and predictable period of time exists today in academic and industrial research groups. One of the most feasible approaches for achieving a prolonged and predictable drug delivery profile in the GI tract is to control the gastric residence time (GRT). Dosage forms with a prolonged GRT, i.e. gastro-retentive dosage forms (GRDFs), provide new and important therapeutic options