Modified Corneosurfametry as a new accelerated high-throughput ex vivo methodology for predicting cleanser effects...

Corneosurfametry (CSM) was originally developed as a tool to predict irritation potential of cleansers. In this method, surface skin stripped using cyanoacrylate is contacted with surfactants/products, rinsed and stained with toluidine blue and basic fuschin dyes. The intensity of staining increases with increases in irritation potential of surfactant. Our objective was to modify the CSM technique to achieve better control of the tape stripping process. Another objective was to correlate the modified CSM (MCSM) with a traditional in-vivo forearm controlled application test (FCAT) for mildness and to explore its utility to assess the state of corneum after a clinical test.

Surface skin cells were tape stripped from forearms of volunteers with D-Squame Adhesive Discs. Discs were treated with a 10% solution of the product in a 96-plate well for 10 min, rinsed, dried and treated with basic fuschin-toluidine blue dye solution, rinsed and dried again. Forearm Controlled Application Test (FCAT) was based on a published protocol. Tape strips obtained after product treatment were also analyzed by the MCSM procedure without additional product treatment.

Mildness/barrier damage assessed from in-vivo FCAT showed a similar ranking to the MCSM results. MCSM, TEWL and Erythema analysis of between-treatment differences showed a good correlation indicating that barrier damage seen in in-vivo studies can be predicted from ex-vivo MCSM studies. MCSM analysis of tape strips after the FCAT study showed that the damage decreased with increase in tape strip number. A moisturizing body wash (MBW) with mild surfactants showed the least damage in all layers. In contrast, harsh dish washing liquid showed significantly higher damage down to several layers. Another MBW with petrolatum in a harsher base showed damage almost similar to that of the harsh dish washing liquid in the surface layers. Thus, the MCSM was able to show underlying damage which would have been normally masked by the deposited petrolatum.

The MCSM assay was shown to be a valuable tool for accelerated high throughput evaluation of mildness of surfactants and fully formulated products. MCSM can also be used to assess the state of the corneum after a product treatment.