Application of the Food and Drug Administration (FDA) bioequivalent guidance of topical dermatological corticosteroid in yellow-skinned Japanese population: validation study using a chromameter.

Abstract

The American Food and Drug Administration (FDA) bioequivalent guidance of topical dermatological corticosteroids in 1995 (the Guidance) requires measurement of the skin blanching response with a chromameter for evaluation of cutaneously applied corticosteroid formulations. The Japanese government decided to apply the same guidelines in 2003, despite there having been no reported trial for the yellow-skinned races. The purpose of this study was to obtain basic data of corticosteroid-induced skin blanching response measured with a chromameter on yellow-skinned races. Four studies were performed according to the Japanese version of the Guidance for Industry using a chromameter on the forearms of healthy Japanese volunteers. This involved: (i) a validation study of proper duration of treatment exposure (dose duration); (ii) a comparison study of two dermatological corticosteroid products that represented different potency classes; (iii) inspection of reproducibility using right and left forearms; and (iv) study of seasonal difference. We showed that: (i) the same medication can give different values of ED(50) (the dose duration required to achieve 50% of the fitted areas under the effect curves [AUEC](max) value) under different dose durations; (ii) ED(50) do not always represent the potency of the corticosteroid; (iii) the results of AUEC at maximum duration were similar, but AUEC at an approximate ED(50) duration time varied widely; and (iv) the results of AUEC were different according to season. In conclusion the dose duration relationships, determination of the AUEC(max), and the ED(50) could be obtained on yellow-skinned races using the FDA method. However, negligible differences were found in our study regarding dose duration, reproducibility and seasonal change.