A Review on Formulation and Evaluation of Sustained-Release Matrix Tablets

Sustained Release (SR) matrix tablets are advanced oral drug-delivery systems designed to maintain a steady therapeutic concentration of drug over an extended period, thereby reducing dosing frequency and enhancing patient compliance. These systems are classified based on the type and role of the matrix-forming polymer into hydrophilic, hydrophobic, lipid-based, biodegradable, and mineral matrices. Matrix tablets are commonly prepared by direct compression, wet granulation, melt granulation, and hot-melt extrusion, depending on drug characteristics and polymer properties. The release of drug from a matrix system usually follows mechanisms such as diffusion, erosion, swelling, or a combination of diffusion–erosion, controlled by the physio-chemical nature of the drug and polymer. To ensure optimal functionality, the formulation undergoes systematic evaluation, including pre-compression tests (flow properties and compressibility), post-compression quality assessments (weight variation, hardness, thickness, friability, and drug content), and in vitro dissolution studies using suitable release media and mathematical kinetic modeling to determine the drug-release pattern. Overall, sustained-release matrix tablets provide a simple, cost-effective, and efficient approach to controlled drug delivery, making them highly suitable for drugs requiring prolonged therapeutic action.