Transdermal Drug Delivery Systems: From the Dawn and Early Stage to the Development and Maturity Stage, and the Future

This review describes the analytical methods for percutaneous absorption and skin permeation of chemical substances and the transdermal drug delivery system (TDDS) that I have been researching for about half a century. This period coincides with that of the dawn and early stage of TDDS through its development to the maturity stage. First, as an introduction, the skin structure, definitions of scientific terms such as percutaneous absorption, skin permeation, skin penetration, types of chemical substances that make contact with the skin, and the skin permeation pathway of chemical substances are outlined. Next, the experimental methods established for percutaneous absorption and skin permeation of chemical substances are described. Then, analytical methods for the percutaneous absorption rate are outlined: i.e., partition to skin barrier and diSusion in the stratum corneum of chemical substances, the meaning of the permeability coe

Automated summary

This article discusses the analytical methods for percutaneous absorption and skin permeation of chemical substances, as well as the transdermal drug delivery system (TDDS) that has been researched for about half a century. It first introduces the skin structure and definitions of scientific terms, then describes the experimental methods established for studying the percutaneous absorption and skin permeation of chemical substances, and finally outlines the analytical methods for the percutaneous absorption rate.