Use of Reflectance Spectrophotometry in the Human Corticosteroid Skin Blanching Assay

A reflectance spectrophotometric method for evaluation of the skin blanching response to topical corticosteroids was evaluated. This blanching response is used, for drug development and regulatory purposes, to assess potency and bioequivalence of topical corticosteroid products. The common method involves the use of a human rater to measure blanching response in the skin. This study evaluated an instrumental alternative to the human rater and used this method to measure the differences between a number of brand name and generic topical corticosteroid products (six creams and six ointments). Products were applied to the forearms of normal volunteers and the blanching responses were assessed after 6 and 16 hours in both occluded and non-occluded skin sites. Only the fluocinolone acetonide generic and brand name preparations were different from each other. The spectrophotometric method proved to be equivalent but not superior to the standard human observer method.