Controlled release of sulfosalicylic acid from poly(vinyl alcohol) hydrogel by electrical stimulation

Abstract

This study evaluated and characterized the use of poly (vinyl alcohol) (PVA) hydrogels as the matrix/carriers for a drug in the Electrically Controlled Drug Delivery System. The drug-loaded PVA hydrogels were prepared by solution-casting using sulfosalicylic acid as the model drug and glutaraldehyde as the crosslinking agent. The average molecular weight between crosslinks, crosslinking density, and mesh size of the PVA hydrogels were determined using the Equilibrium Swelling Theory developed by Peppas and Merril, as well as by scanning electron microscopy (SEM). The release mechanisms and the diffusion coefficients of the hydrogels were studied using a modified Franz-Diffusion cell in an acetate buffer at pH 5.5 and at a temperature of 37 C for 48 hours, in order to determine the effects of crosslinking ratio, electric field strength and electrode polarity. The amount of released drug was analyzed by UV-Visible spectrophotometry. The plots of the amount of drug released as a function of square root of time showed a linear relationship. The diffusion coefficients of drug in PVA hydrogels decreased with increasing crosslinking ratio. Moreover, the diffusion coefficients of drug in the PVA hydrogels depended critically on the electric field strength between 0-5 V and the electrode polarity.