Nose-to-brain drug delivery for the treatment of Alzheimer’s disease: current advancements and challenges

The irreversible destruction of neurons, progressive loss of memory and cognitive behavior, high cost of therapy, and impact on society, desire a better, effective, and affordable treatment of AD. The nose-to-brain delivery approach holds great potential to access the brain without any hindrance of BBB and results in higher bioavailability and thus better therapeutic efficacy of anti-AD drugs.The present review article highlights the current facts and worldwide statistics of AD and its detailed etiology. This is followed by barriers to brain delivery, nose-to-brain delivery, their limitations, and amalgamation with various novel carrier systems. We have emphasized recent advancements in nose-to-brain delivery using mucoadhesive, stimuli-responsive carriers, polymeric nanoparticles, lipid nanoparticles, and protein/peptide delivery for treatment of AD.The available therapies are symptomatic and mitigate the symptoms of AD at the initial stages. In lieu of this, nose-to-brain delivery has the ability to overcome these limitations and increase drug bioavailability in the brain. Various novel strategies including stimuli-responsive systems, nanoparticles, etc. enhance the nasal permeation, protect the drug, and enhance its therapeutic potency. However, successful preclinical data do not assure the clinical success of the therapy, and hence exhaustive clinical investigations are needed to make the therapy available for patients.