Purpose. After its removal from the skin surface, chemical remaining within the skin can become systemically available. The fraction of chemical in the skin that eventually enters the body depends on the relative rates of percutaneous transport and epidermal turnover (i.e., stratum corneum desquamation). Indeed, some investigators have claimed that desquamation is an efficient mechanism for eliminating dermally absorbed chemical from the skin. Methods. The fate of chemical within the skin following chemical contact was examined using a mathematical model representing turnover of and absorption into the stratum corneum and viable epidermis. The effects of turnover rate, exposure duration, penetrant lipophilicity, and lag time for chemical diffusion were explored. Results. These calculations show that significant amounts of chemical can be removed from skin by desquamation if epidermal turnover is fast relative to chemical diffusion through the stratum corneum. However, except for highly lipophilic and/or high molecular weight (>350 Da) chemicals, the normal epidermal turnover rate is not fast enough and most of the chemical in the skin at the end of an exposure will enter the body. Conclusions. Epidermal turnover can significantly reduce subsequent chemical absorption into the systemic circulation only for highly lipophilic or high molecular weight chemicals.

Original languageEnglish
Article number229078
Pages (from-to)1414-1419
Number of pages6
JournalPharmaceutical Research
Issue number11
Publication statusPublished - 30 Nov 2000

Bibliographical note

Funding Information:
This work was supported in part by the U.S. Environmental Protection Agency (CR824053 and PR-DC-99-01933/ 2W9F09) and the U.S. Air Force Office of Scientific Research (F49620-98-1-0060). We acknowledge S. Selim for his assistance in developing the analytical solution to the one-membrane diffusion–convection problem. We thank D. Ma-calady, K.D. McCarley, M.M. Reddy, and L. Sun for their valuable suggestions.


  • Dermal absorption
  • Desquamation
  • Epidermal turnover
  • Mathematical model
  • Stratum corneum
  • Viable epidermis

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry
  • Pharmacology (medical)


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