Older skin results in decreased percutaneous penetration?

• A. Decreased
• B. Increased
• C. No change
• D. Unpredictable

Answer: (A)

The main idea is that the skin’s barrier function is the gatekeeper for any substance trying to penetrate. As people age, the stratum corneum becomes drier and its lipid organization changes, making the barrier more resistant to diffusion. This reduced hydration and altered barrier properties slow the movement of compounds into the deeper skin layers. Additionally, aging brings decreased skin blood flow, which can limit how readily absorbed material is carried away after it gets through the barrier. Put together, these changes tend to lower percutaneous penetration in older individuals.

That’s why the decreased choice best fits. Increased penetration would require a looser, more hydrated barrier, which isn’t typical with aging. No change or unpredictability would ignore these general age-related shifts in skin barrier function.