Izhar Ahmed Syed

A new multi-layer tablet design has recently been proposed for constant drug release: It consists of a drug-free barrier layer on one or both bases of an active core (hydrophilic matrix). This partial coating modulates the core hydration process and reduces the surface area available for drug release. The consequence is an extended release that draws close to a linear release profile. These devices are primarily intended for soluble drugs, while an excessive reduction of the release rate may be obtained with drugs of low solubility. In these devices, time-dependent polymeric barrier is planned to control the release of soluble drugs. Oral Controlled release matrix tablets and layered matrix tablets can be formulated for highly water soluble drugs and sparingly soluble drugs by using polymers in the matrix core and as release retardant layers. This devices delivery the drugs to the colon. This review focuses on the application of the multilayered matrix tablets in the design of controlled released dosage forms employing various types of polymers and layered on the matrices core. Key words: Matrix core, multilayered matrix tablets, zero order release, release retardant layers