In vitro release behavior of dextran-methacrylate hydrogels using doxorubicin and other model compounds

In vitro drug release behavior of doxorubicin, Alizarin Red S, FITC-dextran from photocross-linked dextran-methacrylate hydrogel was studied. The effects of pH of media, degree of substitution (DS) of dextran-methacrylate hydrogel, and molecular weight of model compounds on their release profiles were investigated. Each model compound was successfully incorporated into dextran-methacrylate hydrogel matrix through photopolymerization of the hydrogel precursor. Delayed release of model compounds was observed with these hydrogels having a higher DS. Doxorubicin and Alizarin Red S showed pH-dependent release behavior because of the presence of ionizable groups in their structure. Different types of ionization of doxorubicin and Alizarin Red S resulted in more release into an acidic or alkaline media. As molecular weights of drugs increased, the total amount of released drug at the end of 240 hrs decreased significantly and reached a minimum level as the MW of drugs reached about 10,000. Release of these three model compounds followed simple Fickian diffusion at an early stage of release, i.e., cumulative release of model compounds was proportional to the square root of time. Dextran-methacrylate hydrogel effectively delayed and controlled the release of anticancer antibiotics, doxorubicin.