Solid Lipid Nanoparticles and Nanostructured Lipid Carriers: A Review on Their Role in Targeted Drug Delivery Systems

This review is an overview of the Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs) as the advanced lipid-based drug delivery systems with emphasis on the preclinical animal studies. Their physicochemical properties and formulation strategies and therapeutic uses are explored with a particular focus on how they can be used to enhance drug stability, controlled release and bioavailability. The stable lipid matrix of SLNs can be used to deliver drugs slowly, whereas the partially disordered lipid phase of NLCs offers more space to load drugs, less expulsion of drugs and improved in vivo properties. Comparative studies have shown that NLCs are normally more effective than SLNs in therapeutic efficacy especially in poorly water-soluble or targeted drugs. The review also addresses the existing limitations, such as complexities of formulation and storage stability, and determines the gaps in research, in toxicity evaluation, pharmacokinetics and scalability, and offers directions to guide future preclinical and translation research.