A Scalable Fabrication Method for High Drug-Loading Capacity Hollow Microneedles

Abstract Over the past decade, microneedles, a promising subset of transdermal drug delivery systems, have been extensively studied for their non-invasive, pain-free, delivery of therapeutics across the drug-impermeable stratum corneum. However, traditional microneedles’ drug-loading capacity is low, below clinical levels in many use cases, and thus requires more microneedles in a single array or more frequent application, increasing the chance for discomfort and scarring. In this study, we developed a simplified scalable fabrication process for self-forming, chemically crosslinked, hollow poly(vinyl-alcohol) (PVA)/poly(viny-pyrrolidone) (PVP) microneedles. The hollow microneedle design enables an easily quantifiable and higher loading capacity compared with solid or coated needles. Our process utilizes the material properties of PVA and PVP to reduce the lead time from design to device using a low-polymer fraction solution with low viscosity, capable of producing a batch of microneedles in 24 hours. As a proof of concept, we fabricated 10x10 and single-needle microneedle arrays. The arrays were loaded with Ibuprofen sodium into the hollow cavities without altering the drug. An insertion test was performed to verify that the hollow microneedles had sufficient strength to penetrate dermal tissue without breaking or buckling. The needle integrity after insertion was examined using a digital light microscope. A drug release test was performed to evaluate the capacity and release kinetics of the hollow microneedle system. Our results indicate a higher loading capacity of therapeutics per needle than previously reported in the literature. These results show how a simple fabrication protocol can create robust microneedles with a tunable delivery system compatible with any granulated drug and deliver clinically relevant doses.