The problem of drug delivery into the skin or underlying tissues contrived and devoid of any scientific and practical sense to attempt to deliver a substance to the specific department of our body or to treat or improve over the natural state of the tissues. The enthusiasts of transdermal skin delivery were referring to skin as an inert barrier possessing physical resistance.
In that case, SC was selected as the main ‘enemy’ which must be ‘combated’ either by micro abrasion or superficial peeling or microniddles. In reality, the "delivery enhancing" means have a real wounding impact on skin that trigger the regenerative process, similar to debridement in the chronic wounds treatment - swelling and increased tissue density rising skin impermeability.
Nevertheless, it so happened that in the last few years I have been working in the field of delivery of substances into the skin with the purpose of its rejuvenation. And the idea of my technology emerged after reading an article about possible ways of delivery, stating that delivery through the follicles and sweat channels is impossible because of their total surface area is less than 0.1% of the total surface of the skin. I felt a slight discrepancy in this statement. The one needle syringe injection has far lower ratio than 0.1%, but provides an instantaneous 100% penetration. If we could use these small pore channels leading into the interior of skin to a sub-dermis depth, the delivery of liquid drugs by this way could also be carried out immediately and without any damage to the skin – because the pore inlets are located on the surface of the SC! It only remains to find a way to deliver drugs into the pores!
Pores are a unique part of the skin which provides two most important functions - protection and temperature regulation. Penetration of the pores is extremely difficult because of their miniature structure. Diffusion through the pores is practically impossible, so only a barbaric way is left - injecting liquid formulations directly in each pore orifice.
Since the pore inlet openings are very small, diameter of jet must be smaller than the pore diameter, otherwise pressure will affect the skin area around pores orifice that would lead to pores closing. It follows that the size of the jets must be less than the pore size. Technically, the diameter of the jet is about 50 microns, which can infuse the fluid flow into at least 80% of total number of pores with sizes between 2µm to 400µm. Keep in mind that 50 microns is a diameter of the human hair shaft and it can be potentially blocked by various micro-particles. The rest was easy. A plastic dispenser for infusion of pure solutions provided with two micro-nozzles and vacuum system to set the treated skin area and apparatus were designed. A study was conducted to investigate the delivery of colored aqueous solution in vitro into the skin. The Histology revealed the presence of colored areas in the follicles up to sub-dermis depth. The entire inner surface of the pores bordering with dermis was dye by solutions penetrated into the pores interior, providing a surface of contact was 6 times larger than the outer skin surface.
Many interesting facts regarding the role of different formulations delivered for rejuvenation and restoration of skin lesions were discovered. All this was done without any damage to the protective functions of the SC and other skin compartments.
Intrafollicular infusion confuses the immune system by creating an image of wounding when chemicals reside deep inside. As a result, the immune system generates strong response. But having no wounds.
It was a brief introduction to Affinity, the intra-skin appendages infusion system.