Development of the Pulsed Direct Current Iontophoresis and Its Clinical Application

Abstract

The skin is a primary area of body contact with the environment and is the route by which many chemicals enter the body. The delivery of drugs into and through the skin has been an important area of research for many years. Iontophoresis can be deflned as the process of increasing the rate of penetration of ions into or through a tissue by the application of an external electric fleld across the tissue. Impedance spectroscopy was used to investigate the electrical response of skin to difierent ions, applied currents and flelds. The stratum corneum shows two important electrical features. First, it tends to become polarized as an electrical fleld is applied continuously. Second, its impedance changes with the frequency of the applied electrical fleld. To avoid the counterproductive polarization, the current should be applied in a periodic manner, which is called pulsed direct current. The pulsed direct current generating iontophoretic delivery system was developed. In the state of on, charged molecules are delivered by the iontophoretic difiusion process into the skin. A non-parenteral method for the delivery of macromolecules was developed by using a pulse direct current mode iontophoretic technique.