Evaluation of the effects of topical clobetasol propionate by visual score, electrical impedance and laser Doppler flowmetry

Background/purpose: The intensity of steroid-induced skin blanching is usually evaluated subjectively by a trained observer using a visual score although a few methods have been described for doing this objectively. In this study we wished to establish whether the effects of topical steroids can be detected by measuring the electrical impedance of the skin. Methods: Ten healthy volunteers were treated with three concentrations of clobetasol propionate (0.005, 0.05, and 0.5 mg/mL) on the forearm covered by a dressing overnight. On the following morning, we assessed dermal blanching using a visual score, laser Doppler flowmetry and electrical impedance. Results: Using the visual score, we found dose-response blanching at all concentrations of clobetasol propionate. The laser Doppler flow values declined significantly after the application of clobetasol propionate (0.005 mg/mL (P < 0.01) and 0.5 mg/mL (P < 0.05)), as compared with the test site treated with the vehicle alone. Electrical impedance showed a significant increase in phase index after the application of 0.05 mg (P < 0.01) and 0.5 mg (P < 0.01) of clobetasol propionate, and a significant reduction in real part index after of 0.05 mg/mL (P < 0.05) and 0.5 mg/mL (P < 0.05) compared with the test site treated with the vehicle alone. The magnitude index and imaginary part index were not affected by this steroid. Conclusions: Our findings indicate that the dermal blanching induced by topical corticosteroids can be evaluated with a skin impedance spectrometer.