Recent Advances in Nanoformulation-Based Intranasal Delivery of Bioactive Compounds and Biologics for Neurodegenerative Disorders (NDDs)

As a result of the catastrophic rise in the incidence and transmission of neurodegenerative disorders (CNS), around 24.3% of the world's population was predicted to have Alzheimer's disease (AD), or Parkinson's disease (PD) in 2015. A wide range of drugs have been created over the last three to four decades to address different neurological conditions. Many of the drugs listed for treating cerebral diseases cannot reach the brain because of the blood–brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB), which are biological barriers to the brain. As a result, their effectiveness in treating cerebral disorders is reduced. Phytopharmaceuticals are generally preferred over chemically generated medicines because to their slightly greater patient compliance and lower negative effects. However, special administration techniques that have the ability to drastically change the ADME properties of these potential drugs are required for them to reach their maximum therapeutic index. The intranasal medication delivery channel via an olfactory neural pathway has successfully demonstrated the high efficacy and minimal side effects of the direct targeting technique for the delivery of drugs in the brain in neurological disorders. There are numerous natural compounds that have been studied for the treatment of neuronal disorders and their effective delivery to the targeted site of the brain, including crude extracts of Curcuma longa, Centella Asiatica, Gingko Biloba, Theobroma cacao, Withania somnifera, Bacopa monnieri, etc. and pure substances like—Bilobalide, Quercetin, (-)-Epigal. In comparison to their conventional forms, the therapeutic efficacy, stability, and release kinetics of these extracts/phytocompounds’ nanoformulations are produced and evaluated. And in mouse models of AD produced by commercial medicines, the results of these nanoformulations showed considerably greater neuroprotective efficacy. This shows that the formulations based on natural compounds have the potential to improve the pathological condition of AD and may be pursued as a prospective candidate for clinical research to determine its effectiveness in humans.