In vitro evaluation of idebenone-loaded solid lipid nanoparticles for drug delivery to the brain

Context: Solid lipid nanoparticles (SLN) are regarded as interesting drug delivery systems and their preparation techniques have gained a great deal of attention. Objective: To evaluate the feasibility of preparing idebenone (IDE) loaded SLN from O/W microemulsions by the phase-inversion temperature (PIT) method. Since SLN have been proposed to improve drug delivery to the brain, IDE was chosen as model drug due to its activity in the treatment of neurodegenerative diseases. Materials and Methods: Cetyl palmitate was used as solid lipid to prepare SLN containing two surfactant/cosurfactant mixtures, isoceteth-20/glyceryl oleate (SLN A) and ceteth-20/glyceryl oleate (SLN B) by the PIT method. Results and discussion: All the formulations tested showed a mean particle diameter ranging from 30 to 95 nm and a single peak in size distribution. Stability tests showed that SLN B were more stable than SLN A. IDE release was dependent both on the type of primary surfactant used and the amount of loaded drug. IDE-loaded SLN were effective in inhibiting 2,2'-azobis-(2-amidinopropane)dihydrochloride (APPH)-induced lactic dehydrogenase (LDH) release and reactive oxygen species (ROS) production in primary cultures of astrocytes obtained from rat cerebral cortex. It is noteworthy that SLN B2 (containing ceteth-20 as primary surfactant and 0.7% w/w IDE) were able to prevent entirely both the LDH release and ROS production induced by APPH. Conclusion: The PIT method provided SLN with good technological properties. The tested SLN could be regarded as interesting carriers to overcome the blood brain barrier and increase the efficacy of the loaded drug.