ABSTRACT
Percutaneous absorption is a complex biological process. The skin is a multilayered biomembrane that has certain absorption characteristics. If the skin were a simple membrane, absorption parameters could easily be measured, and these would be fairly constant provided there was no change in the chemistry of the membrane. However, skin is a dynamic tissue and as such its absorption parameters are susceptible to constant change. Many factors and skin conditions can rapidly change the absorption parameters. Additionally, skin is a living tissue and it will change through its own growth patterns, and this change will also be influenced by many factors. This chapter reviews some of the principles and technologies of percutaneous absorption for developers and users of cosmetics.
