A COMPARISON STUDY OF FOUR IN VITRO PHOTOTOXICITY SYSTEMS.

• TR Number: 126
• Authors: Rachui, S.R., Robertson, W.D., Duke, M.A., Allen, R. Stephens & Associates, Inc.

Four in vitro phototoxicity systems were evaluated to determine how closely each method would reproduce the others. Eleven materials were used to evaluate these methods. All eleven materials were run in each system. Phototoxicity was evaluated using the Mattek EPI-100 dermal construct, the Advanced Tissues Sciences’ model 2K1300 dermal construct, and a monolayer of neonatal fibroblasts. The protocol used for these three systems was similar and used cytotoxicity as an endpoint for phototoxicity. The fourth system evaluated used yeast as an indicator of phototoxicity with and an endpoint being zones of inhibition which were generated in response to a phototoxic material. Each of these methods utilized UVA to stimulate phototoxic responses from the materials. Each of these systems have specific advantages and disadvantages. In general, it appears the three dimensional systems are more consistent predictors of phototoxicity. The monolayer system, on the other hand, may be the most sensitive of the models while the yeast method offers a rapid, inexpensive means of screening materials prior to proceeding to more expensive and time consuming testing.