ABSTRACT
Introduction .................................................................................................................................... 221 Mechanisms of Percutaneous Penetration Enhancement ............................................................. 222
Expansion of Preexisting Pathways ........................................................................................... 223 Creation of New Pathways......................................................................................................... 223 Thermal Effects Due to Electroporation .................................................................................... 224
Factors Influencing Percutaneous Penetration Enhancement by Electroporation ...................... 224 Electrical Parameters................................................................................................................... 224 Physicochemical Factors............................................................................................................. 226
Effects of Electroporation on Skin ................................................................................................. 228 Potential Applications..................................................................................................................... 232 Conclusions and Future Prospects................................................................................................. 234 Acknowledgment ........................................................................................................................... 234 References....................................................................................................................................... 235
The administration of drugs to skin is being practiced for centuries to treat local diseases, but this route is being used recently for systemic delivery of therapeutic agents. This route of administration is of special interest because of the advantages offered over other routes including avoidance of gastric degradation and first-pass metabolism in addition to superior patient compliance. However, the major limitation of this route of drug administration is that the skin is permeable to only small lipophilic drugs and is highly impermeable to hydrophilic and macromolecular drugs. This barrier property is mainly attributed to the largely lipophilic outermost layer of the skin, stratum corneum (SC) [1]. The successful transdermal or topical formulation of a drug depends on the permeation rate of the drug across the skin or into the skin to achieve therapeutic levels. As many of the drugs lack favorable physicochemical properties for percutaneous absorption,
percutaneous penetration enhancers are promising in the development of transdermal formulations. An ideal percutaneous penetration enhancer should promote the transport of drugs across or into the skin in a predictable way without any irreversible effects on the skin barrier properties. Several investigations delved into this aspect and studied different enhancement methods including chemical and physical methods to overcome the barrier properties of skin [2-5]. The present chapter focuses on electroporation, an electrical method to enhance the transport of drug molecules across or into the skin by overcoming the barrier of the SC.
