Iontophoresis, magnetophoresis, and electroporation

Abstract

Three distinct types of physical enhancement strategies (iontophoresis, magnetophoresis, and electroporation) for transdermal drug delivery are examined in this chapter. Iontophoresis is the use of a mild electric current for the delivery of charged drug molecules across the skin. In the presence of an electric potential difference, ions diffuse through the epidermis and the dermis, ultimately reaching systemic circulation. An advantage of iontophoresis is that it can be controlled because drug delivery is proportional to electric current, which can be easily modified. The major mechanisms involved in transdermal iontophoretic transport are electromigration, electroosmosis, and passive diffusion. In electromigration, the anode repels positively charged cations and the cathode repels negatively charged anions. Transdermal electroosmosis is the convective flow of a solvent across the skin under the influence of an electric field. The second phenomenon discussed in this chapter is magnetophoresis. Magnetophoresis refers to the utilization of a magnetic field (5–300 mT) for enhanced drug penetration across the skin. In this instance, diamagnetic medications such as lidocaine are repelled from the magnetic field into the skin. The main mechanisms driving magnetophoresis are magnetokinesis and magnetohydrokinesis. Magnetokinesis refers to forced movement of drug molecules under an applied magnetic field. Magnetohydrokinesis-assisted drug permeation is caused by water flux across a membrane due to an external magnetic field. The chapter also focuses on electroporation (applying high-voltage electric pulses to the skin to facilitate drug delivery). Specific examples illustrating the use of these techniques are also described in the chapter.