Sustained release drug delivery systems represent a significant advancement in pharmaceutical technology, offering controlled drug release over extended periods to maintain therapeutic plasma concentrations while minimizing dosing frequency and adverse effects. This review comprehensively examines the formulation strategies, evaluation parameters, and clinical applications of sustained release systems. The discussion encompasses various polymeric matrices, coating technologies, and novel approaches including osmotic systems and floating tablets. Key evaluation methods including dissolution testing, pharmacokinetic studies, and stability assessments are critically analyzed. The review highlights recent innovations in biodegradable polymers, nanotechnology applications, and personalized medicine approaches in sustained release formulations.