Dendrimer as a platform for drug delivery in the skin

Dendrimers are defined as globular, repeatedly branched, macromolecular structures presenting high density of surface functional groups. They have been exploited as targeted drug delivery systems due to their well-defined size and structure. Drugs can be encapsulated in the dendrimer core or complexed to the surface functional groups by electrostatic interactions or covalent conjugations. Dendrimers can improve the absorption of poorly permeable molecules such as hydrophilic compounds and also provide controlled drug release. Their low polydispersity contributes to reducing the experimental and biological variability, providing a more reproducible pharmacokinetic behavior. Interestingly, dendrimers can be tailored to preferably penetrate the skin via the follicular route and a systemic effect should be achieved. The physicochemical and biological properties of dendrimers depend on their surface functional groups, charge, size, and generation which impacts the interaction type of the drug with the skin. Cationic dendrimers, for example, are characterized by enhanced interaction with the skin due to the fact that most proteins are negatively charged. Given that various transport mechanisms may be found according to the type of dendrimer, this chapter will focus on the correlation among their physicochemical and drug absorption properties through the skin. The advantages of combining physical permeation enhancement techniques and dendrimers are also presented.