Current View on Nanosized Solid Lipid Carriers for Drug Delivery to the Skin

Drug delivery into the skin is problematic because, as a natural barrier, it has a very low permeation rate. Several approaches have been made to increase the latter. Current advances in materials science and nanotechnology promise the development of new generations of drug carriers for therapeutic, diagnostic and protective purposes. We have reviewed various lipid drug delivery systems to the skin, with the main focus on solid lipid nanoparticles (SLNs). Further the article concerns possible variants in formulation of SLNs, the selection of lipid compounds and safe stabilizers, and the influence of the physicochemical properties of the drugs on distribution after loading into SLNs. In the last part the advantages of delivery into keratinocytes by SLNs over that of the free drug is addressed, focusing on decreased cytotoxicity of the incorporated drug in SLNs and controlled drug delivery to the subcellular compartments. This knowledge is important in the design and production of advanced solid lipid drug carriers. Additionally, the need for novel approaches or devices to improving permeation is also discussed in the context of moving the nanocarriers to targets deeper in the skin.