Last week I wrote about skin penetration and the difficulty of both creating a product that works and the problems associated with cosmetic products that claim to penetrate.
Today, I stumbled on this interesting article about research out of Japan in which scientists have developed a skin cream that was able to deliver significant amounts of insulin through the skin. Clearly demonstrating that penetration does happen. It’s pretty interesting technology.
Of course, to make the insulin delivering lotion they first surroneding the insulin in proteins, then coated the proteins with a hydrophobic surfactant, then added oligo-arginine peptides as protein transduction domains, then finally dispersed the complex in isopropyl myristate to enhance skin penetration. This is much more advanced and complicated than your standard skin lotion. It also qualifies as a drug, if it can be demonstrated to work on human skin.
Penetration through skin can happen, it just doesn’t happen that easily and if a cosmetic could do it and interacted with skin cell metabolism, it then becomes classified as a drug (at least in the US).