Swelling controlled release of drug from polymetric delivery devices: A local similarity solution

This paper presents a numerically integrated solution of moving boundary pr oblems involving mass diffusion in polymer-penetrant system with a swelling controlled release of drug. Dividing the diffusion process into a finite n umber of fixed boundary problems, we have assumed the local similarity assu mption to valid during the short period. Unlike the existing parameter expa nsion methods, the present solution is expected to he valid over a large ra nge of control parameter representing the difference between solvent concen tration at interface and the equilibrium value within the polymer. At small times, our numerical result shows that a larger values of the control para meter leads to a shorter interval for zero order drug release providing a h igher release rate.