Since their introduction in the early 1990s, solid lipid nanoparticles (SLNs) have received tremendous attention in drug delivery because of their ability to carry and solubilize lipophilic drugs and their small particle size, resulting in increased cellular uptake and absorption. SLNs are composed of physiological lipids, which reduce the risk of acute and chronic toxicity. However, SLNs are prone to instabilities because of their complex crystallization behavior due to the occurrence of polymorphic transitions. This chapter summarizes various aspects of SLNs such as components and production of SLNs, drug loading, drug release, stability, and application of SLNs in drug delivery. This chapter also provides a summary of SLNs as a potential carrier of anticancer drugs, one of the most aggressively expanding areas of research. A special emphasis is placed on the stability and toxicity issues associated with SLNs and their diagnostic applications.
