title: Glucose partition coefficient and diffusivity in the lower skin layers.
abstract: OBJECTIVE
  This work aims to estimate the diffusivity and partitioning of glucose in the dermis and the viable epidermis of human skin.
  
  
  METHODS
  The partition coefficient of glucose between phosphate-buffered saline and dermis, tape-stripped epidermis (TSE), stratum corneum (SC), and split-thickness skin, was measured in vitro using human cadaver skin. Glucose permeability across dermis and tape-stripped split-thickness skin (TSS) was measured using side-by-side diffusion cells. Glucose desorption from TSE and human epidermal membrane (HEM) was measured. All measurements were conducted at 32 degrees C.
  
  
  RESULTS
  The partition coefficient for glucose [mean +/- SD (no. of samples)] was 0.65 +/- 0.09 (n = 25) for dermis, 0.81 +/- 0.06 (n = 10) for TSE, and 0.53 +/- 0.12 (n = 9) for SC. Glucose diffusivity in dermis was calculated to be 2.64 +/- 0.42 x 10(-6) cm2/s (n = 14). Glucose diffusivities in the viable epidermis estimated from TSS permeation, TSE desorption, and HEM desorption were 0.075 +/- 0.050 x 10(-6) cm2/s (n = 5), 0.037 +/- 0.018 x 10(-6) cm2/s (n = 4), and 1.0 +/- 0.6 x 10(-6) cm2/s (n = 4), respectively.
  
  
  CONCLUSIONS
  The tissue/buffer partition coefficient of glucose in all skin layers was found to be less than unity, suggestive of excluded volumes in each layer. Glucose diffusivity in human dermis was found to be one third of its value in water, indicative of hindered diffusion related to the structural components of the tissue. A substantially lower value for glucose diffusivity in viable epidermis is suggested.
authors.affiliation: Faculty of Pharmacy, The University of Jordan, Amman, 11942, Jordan. ekayoub@ju.edu.jo
authors.forename: Enam
authors.initials: E
authors.lastname: Khalil
authors.forename: Kosmas
authors.initials: K
authors.lastname: Kretsos
authors.forename: Gerald B
authors.initials: GB
authors.lastname: Kasting
mesh_terms: D002021:Buffers; D002250:Carbon Radioisotopes; D002463:Cell Membrane Permeability; D020405:Dermis / Q000033:anatomy & histology / Q000378:metabolism*; D004058:Diffusion; D015194:Diffusion Chambers, Culture; D004817:Epidermis / Q000033:anatomy & histology / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D012869:Skin Absorption; D013997:Time Factors
chemical_list: D002021:Buffers; D002250:Carbon Radioisotopes; D005947:Glucose