EVALUATION OF THE VASOCONSTRICTIVE EFFECTS OF TOPICAL STEROIDS BY LASER-DOPPLER-PERFUSION-IMAGING

Corticosteroids are one of the most frequently prescribed local therap eutic treatments. Their potency and bioavailability are tested with di fferent methods. One bf the most accepted methods is the skin-blanchin g test designed by McKenzie. In this study we investigated whether the skin-blanching test designed by McKenzie for screening topically acti ve corticosteroids, producing vasoconstriction, is sufficiently detect able by a laser-Doppler-perfusion-imager (LDPI).Eight sites in two row s on the right forearm of 10 healthy volunteers were treated with a to pical glucocorticosteroid (clobetasol-17-propionate 0.05% (Dermovate(R )), and the bloodflow at each site was measured by the LDPI at differe nt time-steps. Four sites per row were chosen to evaluate the dependen cy of bioavailability according to anatomical differences due to skin changes within the forearm. Furthermore, half of the sites mere occlud ed to demonstrate the difference between occluded and non-occluded sit es in bioavailability. The results show that the LDPI can easily detec t changes in bloodflow due to the vasoconstriction caused by topical c orticosteroid. The results showed significant changes during the diffe rent measurements, with a maximum reaction 30 h after the application of the corticosteroid. The sites under occlusion showed a slower decre ase of laser values than those without occlusion, so that it can be po inted out that occlusion prolongs the bioavailability of corticosteroi ds but does not influence the speed of onset. So far me conclude that this technique is a simple and nontraumatic method for assessing stero id potency. Blanching, as a result of vasoconstriction, can be quantif ied by LDPI measurement. However, LDPI measurements have to be compare d with other techniques, such as the non-traumatic Xe-133 washout tech nique, to find out if the two technologies respond in a similar way.