Background <p>Donepezil, a prevalent anti-Alzheimer’s agent, has the deficiency of low brain bioavailability on oral administration owing to systemic metabolism and restricted blood-brain barrier permeability. The purpose of this study was to utilize a targeted intranasal delivery system based on lactoferrin (LF)-modified PEGylated nanostructured lipid carriers (NLCs) for nose-to-brain transport of donepezil. Methods: A QbD-driven framework was used for a systematic formulation development and optimization. Modeling of molecular interactions guided rational excipient selection was perfomed. The optimized formulation was characterized thoroughly for their physicochemical properties such as particle size, zeta potential and morphology. An analytical-QbD-guided spectrofluorimetric procedure was developed and validated for the sensitive quantification of donepezil in biological matrices. The in-vitro drug release, ex-vivo nasal diffusion studies and in vivo pharmacokinetic and bio-distribution studies were performed on Wistar rats.</p> Results <p>The optimized NLCs were shown to have a particle size consistently under 200&#xa0;nm, high encapsulation efficiency and sustained release profile. The validated spectrofluorimetric method proved to be very sensitive, accurate, and robust for donepezil estimation. In vivo studies demonstrated significantly improved brain targeting after intranasal administration, with a 7.45-fold increase of the AUC in the brain versus the drug suspension and a large brain-to-blood ratio (15.31). The formulation delivered 5744 ng•h/mL in brain AUC indicating effective nose-to-brain delivery. Conclusion: The LF-functionalized PEGylated NLC system developed for the potential delivery of donepezil by intranasal route with improved brain bioavailability and controlled drug release. This strategy promises to improve the therapeutic efficacy in Alzheimer’s disease.</p> Graphical Abstract <p></p>