Computational and Experimental Analysis of Drug-Coated Microneedle Skin Insertion: The Mode of Administration Matters

Abstract

Due to an incomplete understanding of the biomechanics of microneedle skin insertion for therapeutic delivery, translating microneedle device performance to clinical use remains challenging. For drug-coated microneedles, it is hypothesized that the mode of skin insertion plays a significant role in how efficiently the drug is released and diffuses. By modeling application pressure magnitude and duration, both computationally and experimentally, the influence of both factors on drug delivery is evaluated. Building on the previously described computational modeling approaches, the development of a Franz Diffusion Cell assay customized with 3D-printed components for use with microneedle patches with adjustable boundary conditions that capture strain-dependent drug diffusion in porcine skin is described. Findings demonstrate that the modified Franz Diffusion Cells accurately simulate microneedle-skin interactions under load, correlating with computational trends. Specifically, leaving microneedle patches in situ for 10 h reduced drug diffusion by ≈14%, compared to removal after 6 h. Prolonged application pressure may negatively impact on diffusion of the drug from the coated patch due to localized strain on surrounding skin tissue. These findings enhance understanding of how microneedle application mode influences drug delivery and the reliability of ex vivo transdermal testing, enabling more effective predictive pre-clinical assessment of microneedle performance.