Nose-to-Brain Drug Delivery Systems: Emerging Nanotechnology-Based Approaches for the Treatment of Neurological Disorders

Abstract

Nose-to-brain drug delivery has emerged as a promising non-invasive strategy for improving the delivery of therapeutic agents to the central nervous system by exploiting the anatomical connections between the nasal cavity and brain. Conventional systemic administration is frequently limited by the blood–brain barrier, which restricts the cerebral availability of many pharmacologically active compounds. This review examines emerging nanotechnology-based approaches designed to enhance nose-to-brain transport and their potential applications in the treatment of neurological disorders. Particular attention is given to olfactory and trigeminal pathways, nasal physiological barriers and the role of nanocarriers in improving drug solubility, stability, nasal residence time, controlled release and brain bioavailability. Major nanosystems, including liposomes, polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, nanogels and functionalised nanocarriers, are discussed. Their potential applications in Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, brain tumours and other neurological disorders are evaluated. The review also considers important translational challenges, including mucociliary clearance, limited olfactory surface area, formulation variability, nanoparticle safety, dose reproducibility, manufacturing scale-up and insufficient clinical evidence. Recent advances in multifunctional, targeted and gene-delivery nanocarriers indicate considerable potential for improving CNS therapeutics. However, greater standardisation of formulation development, pharmacokinetic assessment, delivery devices and clinical evaluation is required to establish the safety, reproducibility and therapeutic effectiveness of nose-to-brain nanomedicine.