Precision of tristimulus chromameter results from corticosteroid-induced skin blanching

Smith, E.W. and Haigh, J.M. (1998) Precision of tristimulus chromameter results from corticosteroid-induced skin blanching. In: Proceedings of the 2nd World Meeting on Pharmaceutics, Biopharmaceutics and Pharmaceutical Technology. APGI, Châtenay-Malabry, France, pp. 817-818.




The human skin blanching (vasoconstriction) assay has been in use for 3 decades as a tool for the assessment of the release of corticosteroids from topical dosage forms. Application of corticosteroids produces a whitening (blanching) of the skin, the intensity of which is directly related to the clinical efficacyof the formulation. Assessment of the intensity of the induced blanching has classically been, and continues to be, pe1fonned by visual grading, a method which has been criticised because of the subjectivenature of the assessment Recently there has been considerablediscussion in the literature regarding the use of the chromameter as an objective instrumental method of monitoring corticosteroid induced skin blanching for bioequivalence assessment purposes. The FDA has released a Guidance document recommending the use of the chromameter for this purpose. The chromameter measures colour in teims of three indices: the L-scale (light-dark), the a-scale (red-green) and the b-scale (yellow-blue).Any colour can be expressedabsolutelyin terms of these three values.The Guidance protocol suggests the use of only the a-scale values in quantifying the blanching response after correction of the data which includes subtraction of baseline and unmedicated site values. One of the unresolved issues in the FDA Guidance document is this method of data manipulation suggested since the instrument should be capable of assigning an absolute colour value to each site during the vasoconstriction period. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriatenessof these suggested procedures.

Item Type:Book Section
Uncontrolled Keywords:skin-blanching; corticosteroids; tristimulus chromameter results
Subjects:Y Unknown > Subjects to be assigned
Divisions:Faculty > Faculty of Pharmacy
ID Code:634
Deposited By: Prof John Haigh
Deposited On:31 May 2007
Last Modified:06 Jan 2012 16:18
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