Performance and characteristics evaluation of a sodium hyaluronate-based microneedle patch for a transcutaneous drug delivery system

The MicroHyala(®) microneedle (MN) patch was developed to provide a simple, safe, and effective drug delivery system. In this study, we examined the performance and characteristics of our fabricated MN patch to identify potential quality issues with future commercial application. Mechanical failure force analysis identified that the strength of the MN patch was affected by environmental humidity, because higher moisture levels weakened the strength of the MN. Incorporation of all-trans retinoic acid (ATRA) or ovalbumin (OVA) into the MN patch decreased the mechanical failure force by almost 50% of the strength of placebo (without drug) patches. ATRA-loaded MN patches displayed good stability after storage at 4 °C, with more than 90% and 85% of the drug remaining in the patch after 8 and 24 weeks of storage, respectively. Tetanus toxoid- and diphtheria toxoid-loaded MN patches stored for 12 months induced robust antigen-specific immune responses similar to the responses by freshly prepared MN patches. Fluorescence imaging findings suggested that prolonged antigen deposition was induced by MN-mediated fluorescein isothiocyanate-labeled (FITC)-OVA vaccination. Overall, although the strength of MN requires improvement, our developed MN patch appears to be an effective pharmaceutical product providing a simple, safe, and relatively painless approach.