ABSTRACT
Drug delivery from hydrogel based medical devices has been extensively researched over the past 70 years. The adaptable characteristics have been exploited for many applications and have proven successful in replicating or supporting the functions of natural body tissues. Use of mathematical models to provide theoretical understanding of the kinetics of drug release from hydrogels has been fundamental in the advancement of hydrogels as bioactive implants/medical devices. Additional considerations must be made when considering drug release in order to account for the swelling properties of the polymers. The mathematical models used to describe drug release include Fick’s laws of diffusion for reservoir or matrix systems, and consider variations to these models based on sample dimension, crosslinking, variable swelling, and/or erosion of the hydrogel platform. This chapter provides a concise overview of the mathematical models employed to describe drug release from hydrogel systems. More recent advances regarding SMART hydrogels in which release is modulated by environmental stimuli and also devices based on degradation of a chemically attached drug molecule are additionally described. It is highlighted that these models are in fact theoretical in nature and not conclusive to all release systems. However, correct application can ensure drug delivery from hydrogels is a more predictable process.
