Abstract: 
Intranasal administration has demonstrated the ability to cross the blood-brain barrier (BBB) and deliver medications to the central nervous system (CNS) more quickly and extensively than other common routes. Although the mechanism of drug transport from the nose to the brain is not entirely known, it is thought that numerous neural pathways including the olfactory and trigeminal, are involved. Comprehensive research is being done on intranasal nanoemulsion (NE) for brain targeting. Formulations from the area of nanomedicine include nanoemulsions. They are made up of emulsions, which are typically oil in water (sizes between 100 and 300 nm or less), stabilised by one or more surfactants, and subsequently co-surfactants, and delivered as small droplets with a large surface area. To slow down rapid nasal clearance, a mucoadhesive polymer, like chitosan, might be added to the formulation. Nasal nanoemulsions have the potential to be a reliable, non-invasive, and safe drug delivery method for the treatment of CNS diseases as they can target specific areas of the brain. The present developments of intranasal nanoemulsion are the main subject of this review, with a focus on the current difficulties that could serve to guide the direction of future research.

Keywords: Nanoemulsion, Blood Brain Barrier, Central Nervous System, Chitosan, Mucoadhesive.