Stratum corneum anatomical site

Variation in penetration at different anatomic sites Drug penetration is inversely related to thickness of the stratum corneum. Thus, permeability (and often toxicity) is greater in areas of thinner skin, such as the face or scrotum. 

Loffler, H., F. Dreher, and H.I. Maibach. 2004. Stratum corneum adhesive tape stripping Influence of anatomical site, application pressure, duration and removal. Br J Dermatol 151 746. 

The skin is a complex multilayered tissue with a large surface area exposed to the environment. Skin anatomy, physiology, and biochemistry vary among species, within species, and even between anatomic sites within an individual animal or human. Logically these biological factors alone can influence dermal absorption. What is consistent is that the outer layer, the stratum corneum (SC), can provide as much as 80% of the resistance to absorption to most ions as well as aqueous solutions. However, the skin is permeable to many toxicants, and dermal exposure to agricultural pesticides and industrial solvent can result in severe systemic toxicity. 

Black, D., Del Pozo, A., Lagarde, J.M., and Gall, Y. Seasonal variability in the biophysical properties of stratum corneum from different anatomical sites. Skin Res. Technol. 2000 6 70-76. 

Schwindt, D.A. Wilhelm, K.P. Maibach, H.I. Water diffusion characteristics of human stratum corneum at different anatomical sites in vivo. J. Invest. DermatoL 1998, 111, 385-389. 

Large regional variations in percutaneous absorption of compounds are determined by factors including hair follicle density, thickness of the stratum corneum, and vasculature of the region [13]. There is a distinct difference in the penetration of hydrocortisone in different anatomic sites. This suggests that for areas of higher penetrability, such as the face, scalp, scrotum, axilla, and the groin, smaller doses are required and occlusion is not needed [22]. 

---