Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: A Review

Solid lipid nanoparticles (SLN) were developed at the beginning of the 1990s as an alternative carrier system to emulsions, liposomes and polymeric nanoparticles. SLN are defined as aqueous colloidal carrier systems in the size range of 50-1000nm made up of solid lipid matrix. SLN combine advantages of the traditional systems but avoid some of their major disadvantages. They exhibit major advantages such as modulated release, improved bioavailability, protection of chemically labile molecules, cost effective excipients, improved drug incorporation and wide application spectrum. As a novel type of lipid nanoparticles with solid matrix, the nanostructured lipid carriers (NLC) are presented which overcomes the problems associated with SLN such as expulsion of drug from the matrix over the period of time. This paper presents an overview about the selection of the ingredients, different ways of production, drug incorporation and release, characterization of quality and structure, sterilization, storage, stability and applications of SLN & NLC dispersions.