Riluzole-loaded lipid nanoparticles for brain delivery: Preparation, optimization and characterization

Abstract

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, with a median survival of only 2 to 4 years. Riluzole, a drug commonly used in the management of ALS, has a low aqueous solubility and limited bioavailability. ALS treatment is also hindered by the presence of the blood–brain barrier (BBB) that preserves the delicate homeostasis of the cerebral milieu, isolating it and making brain drug delivery exceptionally hard. To overcome these issues, the use of lipid nanocarriers, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), is a promising strategy. In this study, SLN and NLC were prepared and optimized to facilitate riluzole uptake into the brain for ALS therapy. The lipid nanoparticles were characterized through different techniques, with respect to their physicochemical properties (size, zeta potential (ZP), polydispersity index (PDI)), as well as encapsulation efficiency, morphology, stability, in vitro release, crystallinity, and biocompatibility. Riluzole-loaded nanocarriers exhibited characteristics suitable for brain delivery, including mean diameters between 147.2 and 203.1 nm, low PDI (<0.3), and negative ZP between −22.5 and −27.5 mV. Additionally, they were physically stable over 3 months under storage conditions (5 ℃ and 25 ℃), promoting a slow and sustained release of the drug, which was shown to be inside the core of the lipid matrix. Cytotoxicity assays demonstrated that both SLN and NLC did not significantly affect the viability of an hCMEC/D3 cell monolayer at a riluzole concentration up to 10 μM. The results suggest that the developed nanocarriers could be a viable platform to target riluzole to the central nervous system (CNS). Nevertheless, further in vitro and in vivo studies are needed to validate their therapeutic efficacy and safety.