Nano-carrier enabled drug delivery systems for nose to brain targeting for the treatment of neurodegenerative disorders

Abstract A major hurdle for the treatment of neurodegenerative disorders is the inability of drug molecules to cross the blood-brain barrier (BBB). Many anti-Parkinson and anti-Alzheimer drugs lack brain targeting; this impedes their ability to reach maximum effective concentrations in the brain. Many of these drugs possess dose-limiting systemic side-effects which, along with difficult dosage regimens, hinder patient compliance and result in discontinuation of treatment. A number of drug delivery and drug targeting systems have been investigated to increase drug bioavailability and the fraction of the drug accumulated in the targeted area, in order to minimize drug degradation and loss, as well as to reduce harmful side effects. Intranasal delivery has come to the forefront as a method that can bypass the BBB and target drugs directly to the brain as an alternative to invasive methods. However, intranasal delivery presents several barriers such as low permeability of the nasal epithelium, as well as physical or chemical removal of the formulation by mucociliary clearance and enzymatic degradation. Recent advances in nanotechnology offer the potential to overcome these problems. This review compiles recent work that uses nanocarriers to improve the treatment outcomes of neurodegenerative disorders such as Parkinson's (PD) and Alzheimer's disease (AD) through nose to brain targeting.