Microwaves as a Skin Permeation Enhancement Method

Abstract

Living systems are exposed to electromagnetic sources, including microwaves, from different sources such as sun, wireless communication technology, household microwave oven, etc. Microwaves are nonionizing but can affect biological systems through their thermal and non-thermal effects. These effects are presented at all levels of organism from subcellular structures to tissues, organs, and biological membranes, including the skin barrier that is the subject of the present chapter. The skin provides a natural barrier against permeation of chemicals, and, therefore, many drugs cannot be delivered transdermally in therapeutic amounts. To overcome this problem, many enhancement strategies have been employed. These enhancement methods are classified as physical methods and chemical penetration enhancers. This chapter introduces the use of microwaves as a novel physical percutaneous penetration enhancement method. It has been shown that microwaves are able to increase permeation of drugs through the skin in an intensity and time-dependent manner. These effects are due to both thermal and non-thermal effects of microwaves on the skin barrier. Skin permeation studies and mechanistic investigation of interaction of microwaves with skin material by Fourier transform infrared spectroscopy (FTIR) show that microwaves might induce their effects through disruption of intercellular lipids of the stratum corneum.