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Background: Since decades, histamin applications are routinely performed in skin prick tests using a lancet. However, this technique is associated with various drawbacks. Materials and Methods: In healthy human subjects, we investigated the effects of microneedle‐enhanced histamin delivery (wheal size, erythema size) in the skin microvasculature using polarized light spectroscopy imaging (Tissue Viability imaging, TiVi). Histamin was applied on microneedle‐pretreated skin or on ‐untreated skin, to assess the microvascular response in the local skin. Results: In our results, histamin was delivered more rapidly into the skin after microneedle pretreatment compared to passive diffusion, visible as wheal and erythema. Conclusion: The here presented technique might be useful for a personalized drug‐testing system in the future. [ABSTRACT FROM AUTHOR]

Background: The efficiency of transdermal drug delivery may be increased by pretreating the skin with microneedles, but distinct effects of microneedles and the microneedle‐enhanced delivery of vasoactive drugs on the skin microvasculature are still not well investigated. Materials and Methods: In eight healthy human subjects, we measured the microvascular response to microneedle‐induced microtraumas in the skin microvasculature using polarized light spectroscopy imaging (Tissue Viability imaging, TiVi). The microvascular response was assessed for up to 48 hours for three microneedle sizes (300 µm, 500 µm, and 750 µm) and for different pressures and application times. Results: In our results, microneedle application increased the local red blood cell (RBC) concentration for up to 24 hours dependent on the needle lengths, applied time, and force. Conclusion: Optimization of microneedles size, pressure, and application time should be taken into account for future protocols for drug delivery and experimental provocations. [ABSTRACT FROM AUTHOR]