Drug release characteristics of phase separation pHEMA sponge materials

A number of phase separation pHEMA sponge hydrogels have been prepared based on variations in monomer contents, concentration of cross-linking agent, solvent mixture and temperature of polymerization. The loading levels and release profiles of the anti-inflammatory drug prednisolone were examined for each of the pHEMA sponge materials. An effective diffusion coefficient determined by an optimization approach based on the experimental data was used to measure their release characteristics. The effect of morphological variations, revealed by the environmental scanning electron microscopy, and polymer/solvent volume fractions on these properties were discussed.