Modeling the drug release from ionic and covalent co-cross-linked chitosan hydrogels

We propose a model for drug release from co-cross-linked chitosan hydrogels undergoing by surface erosion. The matrix degradation is modeled as an empirical nth. order reaction, and the drug release occurs due to diffusion combined with surface erosion. The erosion is described by a moving front represented by a coordinate transformation method. The model reformulated after scaling is fitted to experimental data using the least squares criterion where the Dynamic Optimization problem enclosing the model is solved applying a sequential algorithm. In this study we consider the diffusion of cisplatin in co-cross-linked chitosan hydrogels where the cross-linkers are glycerol phosphate disodium salt and genipin. The release medium is phosphate-buffered saline (PBS) with lysozyme in concentrations similar to those available in human serum. The increase of cross-linker load reduces the diffusion rate, and increases the amount of drug retained in the matrix.