APPARENT NON-FICKIAN RELEASE FROM A SCLEROGLUCAN GEL MATRIX

Hydrogels, and particularly biopolymeric hydrogels, have recently rece ived tremendous interest as controlled release systems for their pecul iar features such as high biocompatibility, biodegradability, bioadhes ivity, chemical and thermal resistance and good mechanical properties. Among biopolymers, the exocellular microbial polysaccharide scleroglu can appears to be particularly well suited for the formulation of mono lithic hydrogel matrices for controlled drug release. In this work we studied the macroscopic factors influencing the kinetics of a model dr ug release (theophylline) from a scleroglucan hydrogel matrix (2%w/w) and modeled the relevant experimental results. The evidences for the r elease experiments indicate that the kinetics of the processes follow an apparently non-Fickian behavior under different active drug concent ration, temperature and stirring speed. However, by considering the pe culiar nature of the hydrogel matrix and the geometrical features of t he experimental setup in the formulation of the appropriate initial an d boundary conditions, data can be satisfactorily modeled with the cla ssical Fick's law.