What is the percutaneous absorption?
Percutaneous absorption is the absorption of molecules through the skin. The skin is used in thermoregulation and as an effective physical barrier designed to protect the organism from microorganisms, extensive loss of water, ultraviolet radiation and other deleterious agents. The skin is composed of three layers, the epidermis, the dermis and the hypodermis. The epidermis is composed of five layers which are the Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum and the Stratum Basale layer. These layers each have a crucial function with the top layer, Stratum Corneum, being composed of dead skin cells that provide a waterproof layer, which results directly from the two hydrophobic lipid tails pointing in opposite directions which increases the permeability of the skin. Beneath these layers lies the dermis, the location where absorption takes place. Lipid-soluble substances, lipophilic substances, and some hydrophilic substances will be absorbed by trans-epidermal absorption. This is where the substance will simply diffuse through the phospholipid membranes of the cells and into the capillaries in the dermal layer.