Medicinal Chemistry and Pharmaceutical Technology Influence of formulation variables on drug release process from hydrophilic matrix systems

During the last two decades, hydrophilic swellable polymers have been widely used to control the release of a drug from matrix tablet formulations. The increasing need for suitable polymers to achieve the desired drug release profile conducted the pharmaceutical research to widely screening a large variety of both synthetic and natural polymers which show drug release retarding ability. Because of the cost of both synthesis of new polymeric materials and testing their safety, a new focus has been directed towards investigation of the use of polymer blends of pharmaceutically approved polymeric materials as matrix functional excipients to enhance single polymer performance. Swelling of hydrophilic polymeric matrices has been subject of significant research in the last years. In general, swelling-controlled-release systems consist of a drug, which is dispersed in a polymeric matrix. Designing such release systems with desired properties demands a fundamental understanding of molecular factors affecting the release profile. Modified release matrix tablet has been extensively used as one of the most successful oral drug delivery systems by the pharmaceutical industry. By selecting appropriate matrix polymers and using direct compression tableting process, it is possible to produce quality matrix tablets that possess satisfactory processing properties and reproducible drug release profiles.