Iontophoretic drug delivery systems electrodes

In addition to solute structure, a number of factors affecting iontophoretic transport need to be gained for the development of useful optimal iontophoretic drug delivery systems. These include the behavior of solute ions in solution during iontophoresis, mechanisms of solute ion transport through the skin, the effect of different power sources, the choice of electrodes, the composition of vehicles, and the influence of other ions present in the process of drug delivery. 

Fig. 3 Exploded view of an iontophoretic drug delivery system showing major components top housing, printed circuit board assembly, a bottom housing containing reservoirs for placement of electrodes and hydrogels, and an adhesive laminate. (Diagram from International Patent Publication Number WO 96/39222.)...

Srinivasan et al. [17] have described a four-electrode potentiostat system which is suited to maintaining a constant voltage drop across a membrane in a two-chamber diffusion cell. This system was evaluated in connection with trans-dermal iontophoretic drug delivery of polypeptides. 

As indicated in Fig. 1, a transdermal iontophoretic system requires that two electrode assemblies contact the patient s skin. The donor electrode (also known as the delivery or active electrode) contacts the drug reservoir. The counter electrode (also known as the return or receptor electrode) contacts the counter reservoir and completes the electrical circuit by providing a path for the current. The two reservoirs are separated from each other and contact skin over a fixed area. The electrodes apply an electric field across the skin by converting electric current supplied by the battery into ionic current moving in the skin and body. In doing so, a Faradaic reaction takes place at the electrode/ electrolyte interface. As described previously in this chapter, there is generally a linear dependence of the rate of drug delivery on this current. 

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