Advances in Microneedle Technology for Targeted Therapy in Alzheimer’sand Parkinson’s Disease

INTRODUCTION: The fourth major cause of death worldwide is Neurodegenerative Diseases (NDs), including Alzheimer's and Parkinson's disease. The existing therapies have only a small effect on alleviating symptoms, mainly because the therapeutic agents are difficult to cross the bloodbrain barrier. The purpose of the review is to discuss the potential of microneedle-based transdermal delivery systems to improve the delivery of drugs to the central nervous system and thereby manage neurodegenerative diseases effectively. METHODS: The article summarizes and synthesizes the available literature that targets the strategies of microneedle-mediated drug delivery. The literature on the design, composition, pharmacokinetics, and mechanistic benefits of different microneedle platforms for surmounting central nervous system barriers was identified and thematically synthesized. RESULTS: Microneedle systems have emerged as non-invasive delivery systems with the potential for localized and sustained drug delivery, overcoming the stratum corneum and the blood-brain barrier. Micro-needles can be used to deliver small molecules, peptides, and nanoparticles to the brain, thereby avoiding systemic side effects and enhancing drug bioavailability. Some of those designs include dissolving, coated, hollow, hydrogel-forming, and stimuli-responsive microneedles, which have been shown to target the brain and exhibit higher therapeutic efficiency in preclinical models. DISCUSSION: Although technological advances have improved, the clinical translation of microneedlebased strategies remains limited. The future directions could include using microneedles with stem cell-based therapies, CRISPR/Cas9 gene editing, artificial intelligence-based delivery systems, and responsive release technology to facilitate customized treatment. CONCLUSION: The Microneedle-based drug delivery systems are promising in overcoming the current limitations in the treatment of neurodegenerative diseases. Nonetheless, a large-scale clinical validation is necessary to guarantee safety, efficacy, and scalability to be applied to real-life scenarios.