Dendrimer-mediated drug delivery to the skin

Nanoparticles have been increasingly used as carriers for local and systemic drug delivery via the skin. Dendrimers are emerging as the new generation of nanocarriers in skin drug delivery mainly due to their small size, extreme molecular uniformity, and highly functional surfaces. Despite the abundance of investigations which demonstrate the dendrimer-mediated skin delivery enhancement both in vitro and in vivo, there are still controversies over the mechanisms of their action. Based on the critical analysis of currently available data in this field, it is found that the skin delivery enhancement by dendrimers depends on the drug-dendrimer-skin interactions and three potential mechanisms are proposed. Firstly, for some drugs, dendrimers may act as a drug release modifier and speed up the drug dissolution that is the rate-limiting step of percutaneous drug absorption. Secondly, via particle engineering the properties of dendrimers can be tailored to preferably penetrate the skin via the follicular route. Finally, certain low generation dendrimers may impair the stratum corneum barrier function, particularly in the presence of potent vehicles.