Evaluation of intranasal delivery route of drug administration for brain targeting

Abstract

The acute or chronic drug treatments for different neurodegenerative and psychiatric disorders are challengingfrom several aspects. The low bioavailability and limited brain exposure of oral drugs, the rapid metabolism,elimination, the unwanted side effects and also the high dose to be added mean both inconvenience for thepatients and high costs for the patients, their family and the society. The reason of low brain penetration of thecompounds is that they have to overcome the blood-brain barrier which protects the brain against xenobiotics.Intranasal drug administration is one of the promising options to bypass blood-brain barrier, to reduce thesystemic adverse effects of the drugs and to lower the doses to be administered. Furthermore, the drugs ad-ministered using nasal route have usually higher bioavailability, less side effects and result in higher brainexposure at similar dosage than the oral drugs. In this review the focus is on giving an overview on the ana-tomical and cellular structure of nasal cavity and absorption surface. It presents some possibilities to enhance thedrug penetration through the nasal barrier and summarizes somein vitro,ex vivoandin vivotechnologies to testthe drug delivery across the nasal epithelium into the brain. Finally, the authors give a critical evaluation of thenasal route of administration showing its main advantages and limitations of this delivery route for CNS drugtargeting