Iontophoretic Transport of Model Compounds from a Gel Matrix Across a Cellophane Membrane

Abstract

Drug release rates from hydrogels through cellophane membranes were determined using custom-built diffusion cells which were modified to allow the application of current across the membranes. In the absence of a current the results obtained using different concentrations of drug and of the gel indicate the release to be matrix-controlled with a linear relationship between the quantities of drug released and the square root of release time. When a range of direct currents was applied enhanced transport was observed and as the current was increased the release curves became linear with time. The rate of release was also found to increase linearly with the current strength. These results show that an electrical current may be used to increase the rate of drug transport and to alter its release profile under conditions when the unassisted release is matrix rather than membrane controlled.