Emerging nanoformulations for drug targeting to brain through intranasal delivery: A comprehensive review

The blood-brain barrier (BBB) has a very significant role in drug delivery to the brain, which allows passes of only a few molecules. Conventional drug delivery systems have very limited access for the drug delivery to the brain. Several drugs have been developed and approved by FDA for the treatment of various CNS disorders, but most of them cannot cross the BBB to obtain anticipated drug concentration in brain. Hence, usually, most drugs are prescribed in higher doses to get therapeutic effects in the brain, but the several undesired adverse effects have been observed. These systemic side effects reduce the patient's incompliance and finally lead to the nonefficient management of diseases. Further, drug delivery to CNS manifeste several limitation such as solubility, low bioavailability and diminished effectiveness due to BBB. New finding with nanotechnology based approchases have ability to overcome these limitations in brain targeting. With the above context, drug delivery through intranasal route have been arisen as an alternative route over oral and parenteral routes for brain drug targetting. Drugs directly delivered to the brain through olfactory pathway to brain by bypassing BBB. So bioavailability of drug enhanced in brain and drug degradation reduces with minimum wastage of drugs by systemic clearance. Several drug delivery systems have been investigated to enhance the bioavailability with improved drug concentration at the desired site of action to minimize the unwanted systemic side effects. The objectives of the present review article were to summarize different nanocarrier-based strategies for brain drug targeting.