Approaches for the delivery of anti-parkinsonian therapeutic agents via the intranasal route

Parkinson’s disease (PD) is a progressive neurodegenerative disorder primarily associated with dopaminergic neuron loss and dopamine depletion in the brain. Despite the availability of several pharmacological treatments, effective management remains challenging due to the limited ability of most therapeutic agents to cross the blood–brain barrier (BBB). Intranasal drug delivery (INDD) has emerged as a promising, non-invasive strategy to bypass the BBB and deliver drugs directly to the central nervous system through the olfactory and trigeminal pathways. This review summarizes and critically evaluates the various formulation-based approaches that have been explored for intranasal delivery of therapeutic agents in PD, including nanoemulsions, polymeric and lipid nanoparticles, liposomes, niosomes, nanomicelles, and in situ gels. Special emphasis is placed on their mechanisms of brain targeting, pharmacokinetic advantages, and therapeutic outcomes in preclinical and clinical studies. The potential of delivering both dopaminergic drugs and neuroprotective biomolecules—such as peptides, growth factors, insulin, and GLP-1 receptor agonists- via the intranasal route is also discussed. Overall, the review highlights INDD as a versatile and effective platform for enhancing brain delivery of PD therapeutics and paving the way for improved patient outcomes.