Background Dissolving microneedle (DMN) is a transdermal drug delivery system that creates pore in the skin and directly deliver drug through the pore channel. DMN is considered as one of the promising system alternatives to injection because it is minimally invasive and free from needle-related issues. However, traditional DMN patch system has limitations of incomplete insertion and need of complex external devices. Here, we designed film-trigger applicator (FTA) system that successfully delivered DMN inside the skin layers using fracture energy of carboxymethyl cellulose (CMC) film via micropillars. We highlighted advantages of FTA system in DMN delivery compared with DMN patch, including that the film itself can act as DMN applicator. Methods FTA system consists of DMNs fabricated on the CMC film, DMN array holder having holes aligned to DMN array, and micropillars prepared using general purpose polystyrene. We analyzed punching force on the film by micropillars until the film puncture point at different CMC film concentrations and micropillar diameters. We also compared drug delivery efficiency using rhodamine B fluorescence diffusion and skin penetration using optical coherence tomography (OCT) of FTA with those of conventional DMN patch. In vivo experiments were conducted to evaluate DMN delivery efficiency using C57BL/6 mice and insulin as a model drug. Results FTA system showed enhanced delivery efficiency compared with that of the existing DMN patch system. We concluded CMC film as a successful DMN applicator as it showed enhanced DMN penetration in OCT and rhodamine B diffusion studies. Further, we applied FTA on shaved mouse dorsal skin and observed successful skin penetration. The FTA group showed higher level of plasma insulin in vivo than that of the DMN patch group. Conclusions FTA system consisting of simple polymer film and micropillars showed enhanced DMN delivery than that of the existing DMN patch system. Because FTA works with simple finger force without sticky patch and external devices, FTA is a novel and promising platform to overcome the limitations of conventional microneedle patch delivery system; we suggest FTA as a next generation applicator for microneedle application in the future.

Dissolving microneedle (DMN) is an attractive alternative to parenteral and enteral drug administration owing to its painless self‐administration and safety due to non‐generation of medical waste. For reproducible and efficient DMN administration, various DMN application methods, such as weights, springs, and electromagnetic devices, have been studied. However, these applicators have complex structures that are complicated to use and high production costs. In this study, a latch applicator that consists of only simple plastic parts and operates via thumb force without any external complex device is developed. Protrusion‐shaped latches and impact distances are designed to accumulate thumb force energy through elastic deformation and to control impact velocity. The optimized latch applicator with a pressing force of 25 N and an impact velocity of 5.9 m s−1 fully inserts the drug‐loaded tip of the two‐layered DMN into the skin. In an ovalbumin immunization test, DMN with the latch applicator shows a significantly higher IgG antibody production rate than that of intramuscular injection. The latch applicator, which provides effective DMN insertion and a competitive price compared with conventional syringes, has great potential to improve delivery of drugs, including vaccines.

Dissolving microneedles (DMNs) have been used as an alternative drug delivery system to deliver therapeutics across the skin barrier in a painless manner. In this study, we propose a novel heat-melting method for the fabrication of hydrophobic poly(lactic-co-glycolic acid) (PLGA) DMNs, without the use of potentially harmful organic solvents. The drug-loaded PLGA mixture, which consisted of a middle layer of the DMN, was optimized and successfully implanted into ex vivo porcine skin. Implanted HMP-DMNs separated from the patch within 10 min, enhancing user compliance, and the encapsulated molecules were released for nearly 4 weeks thereafter. In conclusion, the geometry of HMP-DMNs was successfully optimized for safe and effective transdermal sustained drug delivery without the use of organic solvents. This study provides a strategy for the innovative utilization of PLGA as a material for transdermal drug delivery systems.

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Finasteride, the most widely used oral alopecia drug, shows several side effects such as hypoactive sexual dysfunction or depression, whereas the topical drug minoxidil demonstrates unsatisfactory efficacy. Thus, there is an increasing need for new alopecia drugs and alternative delivery systems for future alopecia treatment. Researchers have developed dissolving microneedle (DMN), a transdermal drug delivery system, which can be used with minimal invasion. However, DMN has limited application for the alopecia treatment owing to its unsuccessful implantation on the hairy scalp. Here, it is suggested that TOP-M119 (M119), a novel drug acting as a vasodilator in the scalp, and M119-loaded DMN with a specially designed shape can be used for the alopecia treatment. This M119-loaded DMN system is delivered using a newly designed applicator that supports patchless scalp implantation of DMN by microsized pillars designed to prevent accidental skin insertion. Enhanced hair follicle targeting drug delivery and superior alopecia treatment efficacy of specially designed shaped DMN and M119 has been demonstrated through in vitro and ex vivo studies. Moreover, M119-loaded DMN system shows enhanced in vivo efficacy in mouse skin and through expression markers related to hair growth, such as 𝜷-catenin, proliferating cell nuclear antigen, MECA 32, and versican.