DESIGN, OPTIMIZATION AND IN VITRO EVALUATION OF CANNABIDIOL-LOADED NANOSTRUCTURED LIPID CARRIERS FOR THE MANAGEMENT OF REFRACTORY EPILEPSY

Abstract

Background: Refractory epilepsy remains a significant clinical challenge because nearly one-third of patients continue to experience seizures despite treatment with conventional antiepileptic drugs. Cannabidiol (CBD) has emerged as a promising therapeutic agent owing to its anticonvulsant, antioxidant, and neuroprotective properties; however, its clinical application is limited by poor aqueous solubility, extensive first-pass metabolism, and low oral bioavailability. The present study aimed to develop and optimize cannabidiol-loaded nanostructured lipid carriers (CBD-NLCs) to enhance oral delivery and improve in vitro neuroprotective efficacy. Methods: CBD-NLCs were prepared by hot homogenization followed by probe ultrasonication and optimized using a three-factor, three-level Box–Behnken experimental design. The optimized formulation was characterized for particle size, polydispersity index, zeta potential, entrapment efficiency, drug loading, morphology, thermal behavior, crystallinity, in vitro drug release, release kinetics, and storage stability. Neuroprotective efficacy was evaluated in SH-SY5Y neuronal cells using MTT cytocompatibility, glutamate-induced excitotoxicity, intracellular reactive oxygen species (ROS), cellular uptake, and antioxidant assays. Results: The optimized formulation exhibited a particle size of 124.8 ± 3.6 nm, polydispersity index of 0.162 ± 0.009, zeta potential of −31.8 ± 1.7 mV, entrapment efficiency of 94.2 ± 0.8%, and drug loading of 9.7 ± 0.4%. TEM analysis confirmed spherical nanoparticles with uniform morphology, while FTIR, DSC, and PXRD demonstrated successful drug encapsulation and reduced crystallinity. The optimized formulation achieved 93.4 ± 1.5% cumulative drug release over 24 h and followed the Korsmeyer–Peppas kinetic model. Stability studies demonstrated minimal changes in physicochemical properties over three months. In vitro studies showed significantly improved neuronal cell viability (86.8 ± 2.6%), enhanced protection against glutamate-induced excitotoxicity (88.7 ± 2.5% cell viability), marked reduction in intracellular ROS (121.8 ± 5.6% relative fluorescence intensity), approximately 2.9-fold higher cellular uptake, and superior antioxidant activity compared with free cannabidiol. Conclusion: Cannabidiol-loaded nanostructured lipid carriers successfully improved the physicochemical characteristics and in vitro neuroprotective performance of cannabidiol. The optimized formulation demonstrated sustained drug release, excellent stability, enhanced neuronal uptake, and superior antioxidant and neuroprotective activity, highlighting its potential as a promising oral nanocarrier system for the management of refractory epilepsy.