Controlled transdermal iontophoresis of sulfosalicylic acid from polypyrrole/Poly(acrylic acid) hydrogel

Abstract

Transdermal drug delivery system is a system that delivers a drug into a body at a desired site and rate. The conductive polymer-hydrogel blend between polypyrrole (PPy) doped with an anionic drug and poly (acrylic acid) (PAA) were developed as a matrix/carrier for the transdermal drug delivery in which the characteristic releases depend on the electrical field applied. The PAA films and their blend films were prepared by solution casting using ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. A mechanical blending of PPy particles and PAA matrix was then carried out. The thermal properties were investigated by means of the thermogravimetric analysis and differential scanning calorimeter analysis. Moreover, an electrical conductivity of the polypyrrole and drug-loaded polypyrrole was measured by using a two-point probe meter. The drug diffusions of blended PPy/PAA hydrogels and the non- blended ones were determined by using a modified Franz-diffusion cell with an acetate buffer, pH 5.5, at 37 °c, for a period of 48 hours in order to investigate the effects of crosslinking ratio and electric field strength. Amounts of the released drug were measured by UV-Visible spectrophotometry. The diffusion coefficient of the drug was calculated through the Higuchi equation, with and without an electric field and at various crosslinking ratios. The diffusion coefficient decreases with the crosslinking ratio with and without the conductive polymer. The diffusion coefficients are greater at the applied electric field of 1.0 V by an order of magnitude relative to those without electric field.