Insight into central nervous system targeted nanostructured lipid carriers via the nose to brain pathway

In nanomedicine, targeting the central nervous system (CNS) is one of the biggest challenges. The presence of the blood–brain barrier (BBB) leads to the failure of drugs to reach the brain; hence, CNS-related diseases are challenging to treat. Various invasive and noninvasive methods have been established to overcome the difficulty of passing through the BBB. Delivery of drugs by using nanoparticles through the nasal route is one of the noninvasive methods developed to treat CNS disorders. The nose to brain pathway allows direct transport to the brain without crossing the BBB. Among the nanocarriers designed to target the CNS, nanostructured lipid carriers (NLC) are the focus of this review. NLCs appeared as a newer generation of solid lipid nanoparticles (SLN) developed to get over SLN's limitations. They are novel pharmaceutical preparations made of lipids, surfactants and co-surfactants that are physiologic and biocompatible. Liquid lipids (oil) are added to the solid lipid to create a matrix which results in structural flaws in the solid lipids and creates a less ordered crystalline framework that prevents leakage of the drug and provides high drug loading. The imperfection in the internal arrangement of NLCs aids more drug accommodation. A systematic search was performed across the main databases like PubMed, Springer, Scopus, Taylor and Francis, Google Scholar and Wiley. The search applied terms and keywords related to nose to brain delivery, nanostructured lipid carriers and neurodegenerative diseases. This review discusses the anatomy of the nose, associated pathways, advantages and limitations of NLCs, and preparation techniques and recent developments of NLCs delivered via the nose to brain route. The reported records demonstrated the feasibility and potential of NLCs for innovative uses for treatment in the future via the nose to brain route.