Solid lipid nanoparticles (SLN) were developed at the beginning of the 1990s as an alternative carrier system to
emulsions, liposomes and polymeric nanoparticles. The paper reviews advantages—also potential limitations—of SLN for
the use in topical cosmetic and pharmaceutical formulations. Features discussed include stabilisation of incorporated
compounds, controlled release, occlusivity, film formation on skin including in vivo effects on the skin. As a novel type of
lipid nanoparticles with solid matrix, the nanostructured lipid carriers (NLC) are presented, the structural specialities
described and improvements discussed, for example, increase in loading capacity, physical and chemical long-term stability,
triggered release and potentially supersaturated topical formulations. For both SLN and NLC, the technologies to produce the
final topical formulation are described, especially the production of highly concentrated lipid nanoparticle dispersions
.30–80% lipid content. Production issues also include clinical batch production, large scale production and regulatory
aspects (e. g. status of excipients or proof of physical stability).