Nanoemulsions for Targeted Brain Drug Delivery via the Olfactory Pathway: Recent Advances and Perspectives

Abstract: Nanoemulsions, characterized by their sub-micron droplet sizes ranging from 50 to 1000 nm, are emerging as an effective drug delivery system for targeting the brain. Their ability to overcome the Blood-Brain Barrier (BBB) and enhance drug bioavailability makes them a promising tool for managing Central Nervous System (CNS) conditions. This review highlights the advancements in nanoemulsion technology for brain-targeted delivery, particularly through non-invasive intranasal administration. Nanoemulsions exhibit stability, improved solubility of lipophilic drugs, and controlled drug release, which are essential for treating conditions like Alzheimer’s, Parkinson’s, epilepsy, and brain tumors. Intranasal delivery bypasses the hepatic first-pass metabolism and leverages direct pathways, such as the olfactory and trigeminal nerves, to facilitate efficient drug transport to brain tissues. Key studies have demonstrated the efficacy of nanoemulsions in increasing drug residence time, reducing systemic toxicity, and enhancing therapeutic outcomes. Examples include chitosan-coated nanoemulsions for neuroblastoma, antioxidant-loaded formulations for ischemia, and mucoadhesive nanoemulsions for epilepsy and depression. Additionally, nanoemulsions hold potential for treating brain infections and migraines, offering enhanced penetration and sustained release. The findings underscore the versatility and efficacy of nanoemulsions in addressing the challenges of brain-targeted drug delivery. However, further research is needed to optimize their formulation, scalability, and clinical applicability. This review provides a comprehensive overview of current trends and future perspectives for leveraging nanoemulsions to treat neurological conditions.