Modulation of drug release from hydrophilic matrices Literature searches indicate that a wide array of natural and synthetic polymers have been utilized as hydrophilic matrices in monolithic dosage forms

A hydrophilic matrix tablet is the simplest and most cost-effective method of fabricating an extended release (ER) solid oral dosage form. The majority of commercially available matrix formulations are in the form of tablets, and their method of manufacture is similar to conventional tablet formulations: granulation, blending, compression and coating. In its simplest form, a typical ER matrix formulation consists of a drug, one or more water-swellable hydrophilic polymers, excipients such as fillers or binders, a flow aid (glidant) and a lubricant. Other functional ingredients, such as buffering agents, stabilizers, solubilizers and surfactants, may also be included to improve or optimize the release and/or stability performance of the formulation system. Various water-soluble or water-swellable polymers with high molecular weight have been used in hydrophilic matrices, such as hypromellose (hydroxypropyl methylcellulose (HPMC)), hydroxypropylcellulose (HPC) and polyethylene oxide (PEO). HPMC is identified as the most popular polymer in matrix applications because of a number of key features and advantages: 1–5