ABSTRACT
Direct drug brain delivery with minimal systemic exposure attracted great interest and became one of the most challenging research areas with regard to the treatment of central nervous system (CNS)-related diseases. Traditionally, the management of neurological disorders is predominantly performed through peripheral administration of medicines via the oral or intravenous route. While the precise mechanisms governing direct intranasal drug delivery to the CNS are still not completely understood, an accumulating body of evidence has demonstrated that pathways involving nerves connecting the nasal passages to the brain play an important role. The neuronal connection between the nasal cavity and the brain has been extensively investigated on the hypothesis for CNS targeting of drugs. Albeit the numerous examples that support the success and potential of intranasal administration to rapidly deliver a great diversity of neurotherapeutics into the brain, direct transport following intranasal dosing is not always consistently demonstrated.
