Table 3.

Skin models used in IVPT and IVRT studies.

NO.	Skin Models	Examples	Advantages	Disadvantages
1	Human skin models	Full-thickness human skin, dermatomed human skin, the epidermis.	Anatomically identical to human in vivo skin	Ethical considerations, Inconsistency between skin donors
2	Animal skin models	Rats skin, snakeskin, porcine skin, macaque skin.	Histologically similar to human skin	More permeable than ex vivo skin
3	Reconstructed human skin equivalents	Reconstructed full-thickness skin, the reconstructed epidermis (EpiSkin®, SkinEthic®, EpiDerm®).	Structurally close to human skin	More permeable than ex vivo skin
4	Synthetic membranes	Strat-M™, parallel artificial membrane permeability assay [54], phospholipid vesicle-based permeation assay [55].	Reproducible and consistent results	Differences in lipid compositions to the human skin