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Role of 3D Printing in the Development of Biodegradable Implants for Central Nervous System Drug Delivery.

Increased life expectancy has led to a rise in age-related disorders including neurological diseases such as Alzheimer's disease and Parkinson's disease. Limited progress has been made in the development of clinically translatable therapies for these central nervous system (CNS) diseases. Challenges including the blood-brain barrier, brain complexity, and comorbidities in the elderly population are some of the contributing factors toward lower success rates. Various invasive and noninvasive ways are being employed to deliver small and large molecules across the brain. Biodegradable, implantable drug-delivery systems have gained lot of interest due to advantages such as sustained and targeted delivery, lower side effects, and higher patient compliance. 3D printing is a novel additive manufacturing technique where various materials and printing techniques can be used to fabricate implants with the desired complexity in terms of mechanical properties, shapes, or release profiles. This review discusses an overview of various types of 3D-printing techniques and illustrative examples of the existing literature on 3D-printed systems for CNS drug delivery. Currently, there are various technical and regulatory impediments that need to be addressed for successful translation from the bench to the clinical stage. Overall, 3D printing is a transformative technology with great potential in advancing customizable drug treatment in a high-throughput manner.