From nanoemulsions to nanostructured lipid carriers: A relevant development in dermal delivery of drugs and cosmetics

Recent advances in nanotechnology have led to the development of nano-scale drugs and delivery systems to improve drug therapeutic effectiveness. Between the end of ′50 and the beginning of ′60, the first colloidal systems in the nano-metric range were achieved by chance. Several research highlighted the usefulness of these nano-carriers as drug delivery systems to overcome biological barriers later on. Since few drugs are effective after their topical application, due to the barrier function of the skin, colloidal systems have being widely explored as carriers to improve drug skin permeation. In particular, a great deal of attention has been paid to delivery systems based on highly biocompatible and biodegradable components such as lipids and phospholipids. As a result, different types of nano-carriers such as liposomes, microemulsions, solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) have been developed. This review will focus on the nano-carriers arising from the first colloidal systems consisting of water, lipids and surfactants, i.e. microemulsions and their consequent improvement through the development of SLN and NLC. The properties of these nano-carriers will be discussed along with their applications as skin delivery systems both in pharmaceutical and cosmetic fields