Heinkel, Jenny
Diffusion of Drugs Through Human Skin via Transdermal Patches
Manoranjan, Valipuram S.
The permeability of human skin has been studied for many years and yet it is still incompletely understood. The skin is a unique organ in that it acts as a shield to the body protecting it from environmental toxins. This shield, so to speak, is made up of three layers; the stratum corneum, or horny layer, the epidermis and the dermis. The upper most layer, the stratum corneum is the most impermeable of all the layers. It is suggested that once a drug can diffuse through the stratum corneum layer the drug will easily diffuse through the other two layers. Thus, the topic under study is that of diffusion through the stratum corneum.
Each drug has a different chemical structure to it. Some of these structures are more permeable than others. For example, drugs of high water and oil solubility tend to be more permeable to the skin than drugs with low water and oil solubility. The permeability of skin is also highly pH dependent. Due to these unique characteristics of the skin, diffusion of drugs through it has become a difficult process.
The diffusion model described in this research can, and has, been applied to several different types of drugs, such as nicotine, herbal supplements for weight loss and hormones for contraceptive purposes. The end result of this research project is to design a transdermal patch which releases insulin at the precise rates necessary.