Enhanced transdermal drug penetration by the simultaneous application of iontophoresis and sonophoresis

In this paper, the synergistic effect of the combination of iontophoresis and sonophoresis for transdermal penetration of a water-soluble model drug was investigated using a Franz-type cell and excised hairless mouse skin. By iontophoresis or sonophoresis only, there was not much enhancing effect; however, about 10 times the penetration enhancement was observed with their combination. Environmental scanning electron microscopic observation of the skin surface suggested that the application of ultrasound formed a submicron-level pit in the stratum corneum while the iontophoresis promoted the penetration of the drug through this passage in the skin.