COMPARISON STUDY ON USING PULSED CURRENT AND DIRECT CURRENT IONTOPHORETIC SYSTEMS IN THE ENHANCEMENT OF METHYLENE BLUE TRANSPORT THROUGH HAIRLESS RAT SKIN

摘要

Electric pulses and direct current iontophoresis to permeabilize rat stratum corneum were applied to demonstrate enhanced epidermal transport of methylene blue, a water-soluble cationic dye. Electrodes were placed on the outer surface of excised full-thickness rat skin, and methylene blue was applied to the skin beneath the active electrode (i.e positive electode). The pulsing square wave electric field used was 10 Volts, with 1, 2, 4, 8 or 16 k pulse/sec. The direct current electric field used was 6 Volts, with 0.2, 0.4, 0.8, 1.6 or 3.2 mA/cm2. An electric exposure dose lasted for 10 minutes. A comparative study was carried out between these two groups to determine the best iontophoresis conditions of delivering methylene blue in excised full-thickness rat skin. The amount of dye penetrated in a skin sample was determined from the absorbance spectra of dissolved punch skin biopsy sections. Penetration depth and concentration of the dye were measured with light and fluorescence microscopy of cryosections. The maximum absorption for MB is 8 k pulse/sec., and 0.2 mA/cm2 for direct current.