Kelchen Megan N, Holdren Grant O, Farley Matthew J, Zimmerman M Bridget, Fairley Janet A, Brogden Nicole K
Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa College of Pharmacy, Iowa City, Iowa, USA.
Pharm Res. 2014 Dec;31(12):3478-86. doi: 10.1007/s11095-014-1435-y. Epub 2014 Jun 20.
The objective of this study was to optimize a reproducible impedance spectroscopy method in elderly subjects as a means to evaluate the effects of microneedles on aging skin.
Human volunteers were treated with microneedles at six sites on the upper arm. Repeated impedance measurements were taken pre- and post-microneedle insertion. Two electrode types were evaluated (dry vs. gel), using either light or direct pressure to maintain contact between the electrode and skin surface. Transepidermal water loss (TEWL) was measured as a complementary technique.
Five control subjects and nine elderly subjects completed the study. Microneedle insertion produced a significant decrease in impedance from baseline in all subjects (p < 0.05, regardless of electrode type or pressure application), confirming micropore formation. This was supported by a complementary significant increase in TEWL (p < 0.05). The gel*direct condition produced the lowest variability between measurements, as demonstrated by a coefficient of variation of 3.8% and 3.5% (control and elderly subjects, respectively). This was lower than variation between TEWL measurements at the same sites: 19.8% and 21.6% (control and elderly subjects, respectively).
Impedance spectroscopy reproducibly measures micropore formation in elderly subjects, which will be essential for future studies describing microneedle-assisted transdermal delivery in aging populations.
本研究的目的是优化一种适用于老年受试者的可重复阻抗光谱法，以此作为评估微针对老化皮肤影响的手段。
人类志愿者的上臂六个部位接受了微针治疗。在微针插入前后进行了重复的阻抗测量。评估了两种电极类型（干式与凝胶式），通过轻度或直接施压来保持电极与皮肤表面的接触。经表皮水分流失（TEWL）作为一项补充技术进行了测量。
五名对照受试者和九名老年受试者完成了研究。微针插入后，所有受试者的阻抗均较基线显著降低（p < 0.05，无论电极类型或施压方式如何），证实了微孔的形成。这得到了TEWL显著增加（p < 0.05）的补充支持。凝胶*直接施压条件下测量值之间的变异性最低，对照受试者和老年受试者的变异系数分别为3.8%和3.5%。这低于同一部位TEWL测量值之间的变异：对照受试者和老年受试者分别为19.8%和21.6%。
阻抗光谱法可重复测量老年受试者的微孔形成，这对于未来描述老年人群中微针辅助经皮给药的研究至关重要。
