Effect of Aging on Passive Drug Diffusion Through Human Skin

In the present work, a comparative study of the passive diffusion of a drug through the intercellular (ICR) and sweat duct (SDR) routes of human skin has been performed. We have tested trans-cinnamic acid and caffeine as drugs, as those are the most commonly available compounds. The effect of aging on transdermal drug diffusion has been considered by performing the above analysis for young age (< 40 years) and old age (> 60 years). A mathematical model based on Fick’s law is adopted to understand drug diffusion through various layers. Each of the routes is described by a compartment model along with the donor and receiver compartments at the top and bottom, respectively. Code is validated by comparing present results with the published experimental findings. For both tested drugs, it is found that the intercellular route provides a faster route of drug delivery as compared to the sweat duct route. It is also found that the amount of drug diffusion increases upon the aging of human skin.