dermatology - DermaAmin

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Basics of Metal Skin Penetration:
Scope and Limitations
Jurij J. Hosty´nek and Howard I. Maibach
Department of Dermatology, University of California at San Francisco
School of Medicine, San Francisco, California, U.S.A.
INTRODUCTION
The skin as target organ presents imponderable and wide margins of variability.
In vivo, permeability is subject to homeostasis regulating the overall
organism; in vitro, the sections of skin used for diffusion experiments are
likely to present artifacts. To further complicate the matter, diffusion of
metals appears to defy laws empirically derived for passive diffusion across
biological membranes. Endeavors to define rules governing skin penetration
by metals toward derivation of predictive quantitative structure–diffusion
relationships for risk assessment, thus, have been unsuccessful, and penetration
of the skin still needs to be determined separately for each metal compound,
by in vitro or in vivo assays. Because diffusion through biological membranes
is highly metal specific, and, in addition, metal ions’ valence is mutable during
the process of diffusion, molecular physicochemical parameters alone do not
suffice to model migration of electrolytes into and through the strata of the
skin. Certain factors are closely interrelated, and their combined effects are
neither entirely understood nor predictable. For example, unless the dynamics
This chapter, in part, was reprinted from Hosty´nek JJ, Maibach HI. Skin penetration by metal
compounds with special reference to copper. Tox Mech Meth 2006; 16:245–265, with permission
of Informa Healthcare.
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