Swelling Controlled Release of Drug from Polymetric Delivery Devices: A Local Similarity Solution

This paper presents a numerically integrated solution of moving boundary problems involving mass diffusion in polymer-penetrant system with a swelling controlled release of drug. Dividing the diffusion process into a finite number of fixed boundary problems, we have assumed the local similarity assumption to valid during the short period. Unlike the existing parameter expansion methods, the present solution is expected to be valid over a large range of control parameter representing the difference between solvent concentration at interface and the equilibrium value within the polymer. At small times, our numerical result shows that a larger values of the control parameter leads to a shorter interval for zero order drug release providing a higher release rate.