ABSTRACT
I. INTRODUCTION There is an increasing demand for data describing the rate, degree, and route of penetration of compounds across human skin. First, there is a requirement to optimize the delivery of dermatological drugs into various skin strata for maximum therapeutic effect. Second, the transdermal and topical routes have become popular alternatives to more traditional methods of drug delivery. A third stimulus has been the toxicological and risk assessment implications of the everyday use of a wide range of potentially harmful materials in the agrochemical, chemical, cosmetic, household, and pharmaceutical sectors. This has been driven largely by regulatory and safety bodies and a perceived need for improved data on the permeability of the skin to xenobiotics. For example, the U.S. Environmental Protection Agency (EPA) is currently addressing the issue of the dermal absorption testing of 80 compounds designated by the Occupational Safety and Health Administration (OHSA) and the Interagency Testing Committee (ITC) as worthy of particular interest (1,2).
