Transdermal Drug Delivery System: Current Status and Clinical Application of Microneedles

As a new type of transdermal drug delivery system (TDDS), microneedles have garnered significant attention for their noninvasiveness, portability, controllable drug administration, and wide-ranging loading capacity. While initially designed for transdermal administration via the stratum corneum for minimizing adverse reactions associated with systemic administration and enhancing patient compliance, microneedles have recently found applications in a multitude of medical contexts. Hence, their potential in medical applications transcends mere drug delivery. Recent reviews on microneedles have extensively covered various aspects, including needle types, materials, and manufacturing methods, as well as their applications in treating skin diseases. This review aims to provide a comprehensive overview of the diverse designs and applications of microneedles from different new perspectives, which encompass traditional integrated microneedles as well as more intelligent and structurally optimized ones in nowadays. Additionally, this review offers a comprehensive analysis of the material properties utilized in microneedles for different applications, including nondegradable materials and degradable materials. Furthermore, the review presents the wide-ranging applications of these microneedles in different medical scenarios such as regeneration and repair, disease treatment, monitoring, and prevention. Moreover, the discussion of the article highlights the future clinical applications of microneedles and the necessary efforts required to achieve their widespread adoption. This review serves as a valuable reference for bridging the gap between the laboratory setting and the clinical practice in terms of using microneedles in medical scenarios.