abstract

The quest for enhanced therapeutic outcomes and improved patient adherence continues to drive innovation in pharmaceutical formulation, with non-implantable drug delivery systems (NIDDS) at the forefront. Achieving precise control over drug release kinetics from NIDDS is paramount, a function predominantly orchestrated by their polymeric coatings. This paper presents a comprehensive mechanistic study aiming to elucidate the intricate interplay between diverse coating formulations and their impact on drug release profiles. We delve into the fundamental physicochemical mechanisms governing controlled release, including diffusion through polymer matrices, dissolution of the drug and/or coating, polymer swelling, and material erosion/degradation. For each mechanism, we critically analyze how specific characteristics of the polymeric coating – such as polymer type, molecular weight, cross-linking density, hydrophilicity, thickness, and porosity – mechanistically modulate drug transport. Furthermore, the paper provides a detailed review of widely applied mathematical models (e.g., Higuchi, Korsmeyer-Peppas, zero-order kinetics) and discusses how their parameters are influenced by coating design, offering insights into their utility for predicting release behavior. The role of auxiliary excipients, such as plasticizers and pore formers, in fine-tuning release characteristics is also systematically explored. By integrating principles from polymer science, transport phenomena, and pharmaceutical engineering, this study consolidates current understanding into a unified mechanistic framework, thereby facilitating the rational design and optimization of next-generation NIDDS for tailored therapeutic delivery.