MATHEMATICAL-MODELING OF DRUG-RELEASE FROM HYDROGEL MATRICES VIA A DIFFUSION COUPLED WITH DESORPTION MECHANISM

Model calculations have been performed to account for the kinetics of drug release from polymeric matrices where both diffusion and desorption mechanisms control the overall release rate. The model incorporates both a desorption term, based on Langmuir kinetics, and a transient Fickian diffusion term and is solved for infinite sink boundary conditions. Solutions by both finite difference and finite element techniques indicate the effects of binding interaction strength, binding capacity, amount of drug loaded and rate of desorption on the release kinetics of drugs adsorbed to polymer matrices. Simulation results indicate that it is possible to modulate the net release rates of drugs over a wide range by altering the binding parameters enumerated above as well as drug diffusivities in the matrix.