Evaluation of Yucatan micropig skin for use as an in vitro model for skin permeation study

Skin permeation rates of five non-steroidal anti-inflammatory drugs, three of them lipophilic (ibuprofen, indomethacin and ketoprofen) and two hydrophilic (sodium diclofenac and antipyrine), through Yucatan hairless micropig (YMP) full-thickness skin were determined in vitro using Franz-type diffusion cells, and the usefulness of YMP skin as an animal model skin was investigated. Five-month-old YMP skin showed small variation with respect to drug permeation rates, if the region of skin site was the same. But skin from 6-month-old YMPs showed faster and varied permeation rates due to skin defects. In the case of hydrophilic drugs, no effects on permeation due to the region from which the skin was obtained were observed, although higher permeation rates were observed through the flank than through dorsal skin in the case of ibuprofen and ketoprofen. For YMP skin, the permeation coefficients of drugs were lower than those for hairless rat skin, especially for hydrophilic drugs. Compared with reported human data on permeation coefficients, the permeation coefficients of drugs through YMP skin were 1/2-1/8 of those through human skin, regardless of whether the drugs were hydrophilic or lipophilic. YMP skin could be used as an in vitro animal skin model because of the reproducibility of the permeation rate of drugs through this skin and its similarity to human skin.