Which skin region has a higher penetration ratio due to a thinner stratum corneum?

Which skin region has a higher penetration ratio due to a thinner stratum corneum?

• A. Scrotum (thinner stratum corneum)
• B. Heel (thicker stratum corneum)
• C. Palm of hand
• D. Back of forearm

Answer: (A)

Penetration through the skin is largely governed by the stratum corneum, the outermost barrier. A thinner stratum corneum offers less resistance to diffusion, so more of the drug can pass per unit area. Among common skin sites, the scrotum has a very thin stratum corneum, making it significantly more permeable. The heel has a thick stratum corneum, providing strong resistance to penetration; the palm is also thick and keratinized, and the back of the forearm is of intermediate thickness. Because of its notably thinner barrier, the scrotum shows a higher penetration ratio.

Penetration through the skin is largely governed by the stratum corneum, the outermost barrier. A thinner stratum corneum offers less resistance to diffusion, so more of the drug can pass per unit area. Among common skin sites, the scrotum has a very thin stratum corneum, making it significantly more permeable. The heel has a thick stratum corneum, providing strong resistance to penetration; the palm is also thick and keratinized, and the back of the forearm is of intermediate thickness. Because of its notably thinner barrier, the scrotum shows a higher penetration ratio.