ABSTRACT
INTRODUCTION The structure of human skin is a formidable barrier to determining the efficacy of topically applied compounds. Much emphasis is placed on the efficacy of topically applied therapeutic agents and developing appropriate formulations (pharmaceuticals) to facilitate their delivery. Because the structure of the skin, especially the stratum corneum, in relation to its role in percutaneous absorption has been discussed in Chapter 1 in the companion volume (1), this aspect is not being considered here. The emphasis in this chapter is on introducing key concepts in dermatological and cosmetic development, which are dealt with in greater detail in the other chapters of this book.
