Sommer A, Veraart J, Neumann M, Kessels A
Department of Dermatology, University of Maastricht, The Netherlands.
Acta Derm Venereol. 1998 Jan;78(1):15-8. doi: 10.1080/00015559850135751.
Corticosteroids are one of the most frequently prescribed local therapeutic treatments. Their potency and bioavailability are tested with different methods. One of the most accepted methods is the skin-blanching test designed by McKenzie. In this study we investigated whether the skin-blanching test designed by McKenzie for screening topically active corticosteroids, producing vasoconstriction, is sufficiently detectable by a laser-Doppler-perfusion-imager (LDPI). Eight sites in two rows on the right forearm of 10 healthy volunteers were treated with a topical glucocorticosteroid (clobetasol-17-propionate 0.05% (Dermovate), and the bloodflow at each site was measured by the LDPI at different timesteps. Four sites per row were chosen to evaluate the dependency of bioavailability according to anatomical differences due to skin changes within the forearm. Furthermore, half of the sites were occluded to demonstrate the difference between occluded and non-occluded sites in bioavailability. The results show that the LDPI can easily detect changes in bloodflow due to the vasoconstriction caused by topical corticosteroid. The results showed significant changes during the different measurements, with a maximum reaction 30 h after the application of the corticosteroid. The sites under occlusion showed a slower decrease of laser values than those without occlusion, so that it can be pointed out that occlusion prolongs the bioavailability of corticosteroids but does not influence the speed of onset. So far we conclude that this technique is a simple and non-traumatic method for assessing steroid potency. Blanching, as a result of vasoconstriction, can be quantified by LDPI measurement. However, LDPI measurements have to be compared with other techniques, such as the non-traumatic 133Xe washout technique, to find out if the two technologies respond in a similar way.
皮质类固醇是最常用的局部治疗药物之一。其效力和生物利用度通过不同方法进行测试。最被认可的方法之一是麦肯齐设计的皮肤变白试验。在本研究中，我们调查了麦肯齐设计的用于筛选产生血管收缩作用的局部活性皮质类固醇的皮肤变白试验，是否能被激光多普勒灌注成像仪（LDPI）充分检测到。对10名健康志愿者右前臂两排共8个部位外用糖皮质激素（丙酸氯倍他索0.05%（得肤宝）），并在不同时间点用LDPI测量每个部位的血流。每行选择4个部位，以评估由于前臂皮肤变化导致的解剖差异对生物利用度的影响。此外，一半的部位进行封包，以证明封包部位和未封包部位在生物利用度上的差异。结果表明，LDPI能够轻松检测到局部皮质类固醇引起的血管收缩导致的血流变化。不同测量期间结果显示出显著变化，在应用皮质类固醇后30小时出现最大反应。封包部位的激光值下降速度比未封包部位慢，因此可以指出封包可延长皮质类固醇的生物利用度，但不影响起效速度。到目前为止，我们得出结论，该技术是一种评估类固醇效力的简单且无创的方法。血管收缩导致的皮肤变白可通过LDPI测量进行量化。然而，LDPI测量必须与其他技术（如无创的133Xe洗脱技术）进行比较，以确定这两种技术的反应是否相似。
