Are Nanostructured Lipid Carriers (NLC) better than Solid Lipid Nanoparticles (SLN) for delivering abiraterone acetate through the gastrointestinal tract?

Abiraterone acetate (AbA) is a progesterone derivative indicated for the treatment of metastatic prostate cancer. This BCS (Biopharmaceutics Classification System) Class IV molecule has an extremely poor oral bioavailability (<10 %), notably due to its very low water solubility and intestinal permeability. Among the few existing galenic strategies to improve AbA's oral bioavailability, lipid nanoparticles such as Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) are relevant nanovectors. The objective of this study is to develop and compare SLN and NLC for oral delivery of abiraterone acetate. Both SLN and NLC are biocompatible, biodegradable and produced by high pressure homogenization (HPH), an ecological-friendly manufacturing process, organic solvent-free and easily scalable. The HPH process allowed the formation of AbA-loaded SLN and NLC with particle size lower than 160 nm and high encapsulation efficiencies. The addition of a liquid lipid significantly reduced the mean diameter of the nanoparticles, reflecting the greater benefit of the NLC formulation compared to SLN. Both SLN and NLC formulations offered an important protection of AbA in intestinal media, with a better stability for NLC. When encapsulated in SLN or NLC, the AbA is strongly retained by the nanoparticles, whatever the dissolution medium, which means that both formulas are able to protect and retain the drug in the intestinal tract, right up to its delivery to the enterocytes surface. High concentrations of nanoparticles were administered without cytotoxicity, especially for the NLC, which provides a real added value in terms of biocompatibility with Caco-2 cells. Finally, the nanoparticles were able to penetrate into enterocytes by the transcellular route, demonstrating an intense cellular internalization.