Purpose To validate the application value of Banna miniature pig inbred line skin (hereinafter referred to as “pig skin”) in the evaluation of analgesic transdermal absorption drugs, the comparison of the histomorphology of pig and human skin and conducting in vitro permeability testing of analgesic percutaneous absorption drugs were carried out.
Methods The structural morphology of two kinds of skin tissues were compared through HE staining, Masson staining, elastic fiber staining, and transmission electron microscope observation. Salicylic acid solution, diclofenac diethylamine cream and lidocaine gel patch were selected as model drugs, drug permeation experiments were carried out through Franz diffusion cell, and the drug mass concentration through skin was detected by microplate reader and high-performance liquid chromatography method.
Results The results of HE staining, Masson staining, and transmission electron microscope showed that the skin layers and cell composition of the pig skin were similar to those of human skin. But the epidermis of pig skin was extremely significantly thicker than the epidermis of human skin (P<0.01), and the dermis of human skin was extremely significantly thicker than the dermis of pig skin (P<0.01). The thickness of various parts in the pig skin from top to bottom in turn was shoulder, buttock, back, and abdomen. During the 0-24 hours of the permeability testing, on the most of the time points, there was no significant differences in the mass concentration of the three drugs between the human skin and the pig skin (P>0.05).
Conclusion The tissue morphology of the pig skin is similar with human skin, and the permeability of the three drugs between the two skins are also relatively similar. The pig skin can be used for in vitro permeability evaluation of analgesic transdermal absorption drugs.
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