Application of ionic liquids to intranasal formulation targeting the brain

In developing drugs to treat intractable central nervous system（CNS）diseases, the incidences of which are increasing, there is an urgent need to develop technologies to deliver therapeutic drugs to the brain. The blood-brain barrier（BBB）protects and prevents most orally or intravenously administered drugs from reaching the brain, making it challenging to treat CNS diseases with these drugs. Recently, intranasal administration has attracted attention as a method for delivering therapeutic drugs directly to the brain by bypassing the BBB, as a direct route from the nose to the brain exists. However, mucociliary clearance and nasal mucosal tissue prevent drug absorption from the nasal cavity via this route；therefore, overcoming these issues is essential for efficient drug delivery from the nose to the brain. This article introduces the application of ionic liquids, which have recently attracted attention as materials of drug delivery system in nose-to-brain delivery.