Microneedles: An Innovative and Increasingly Promising Method for Transdermal Drug Delivery Systems

The most commonly used methods for transdermal drug administration include hypodermic needles, topical creams, and transdermal patches. However, the effectiveness of many therapeutic agents is often limited by the stratum corneum, the outermost skin layer, which acts as a barrier, preventing most molecules from reaching their target sites. A new drug delivery system, known as microneedles, offers a promising solution by enhancing drug penetration through this barrier and addressing the limitations of traditional formulations. The core principle behind microneedles is their ability to disrupt the skin, creating micron-sized channels that allow drugs to reach the epidermis or upper dermis, from where they can enter systemic circulation directly. This review explores the various potentials and applications of microneedles, which can be fabricated in forms such as solid, dissolving, hydrogel, coated, and hollow types. The choice of fabrication method depends on the microneedle material and type. Microneedles have found increasing applications in fields such as oligonucleotide delivery, vaccine administration, insulin delivery, and cosmetics. Although several microneedle products are already entering the market, further research is needed to address the challenges that must be overcome before microneedles can achieve widespread commercial success.