ABSTRACT
An introduction to iontophoresis was presented in Chapter 1. In this chapter, details on iontophoretic delivery such as pathways, mechanism, theory, factors affecting delivery, and some examples will be presented. Other examples for delivery of proteins are presented in Chapter 8, and some case studies are discussed in Chapter 7. Several iontophoretic devices are on the market, and these are discussed in Chapter 10, Section 10.6, which provides a detailed discussion of the commercial development of iontophoresis and other skin enhancement technologies, including some of the studies conducted in human subjects. It is important to understand some of the very basic terminology used in the •eld. The electronic current from a power source is delivered to a solution where it is converted to a šow of ions taking place through the solutions and skin. The terminals leading the current into and out of the solution are electrodes, the positive pole being the anode and the negative pole being the cathode. The electrode may be smaller than the drug reservoir that is in contact with the skin. The current density is de•ned as the current intensity per unit cross-sectional area. In general, the current density will vary from point to point in any system, and the value calculated from the amperes divided by the surface area is just an average value at the treatment surface.
