Regular article AATEX 2(4):183-191
Photohemolysis testing of red blood cells (RBC), a phenomenon based on photodynamic reaction of the cell membrane, was validated as a possible alternative method to predict phototoxicity of chemicals after optimization of various factors. The data from phototoxicity test results in guinea pigs for 24 chemicals (8 fragrances, 5 UV absorbers, 4 drugs, 4 antimicrobials and 3 dyes) were compared. The sensitivity, specificity, positive predictive value, negative predictive value and equivalence of the in vitro test were 67%, 73%, 60%, 79% and 73%, respectively. Four chemicals were identified as false positive compounds, and two psoralens, of which the phototoxic mechanism is different from cell membrane damage, were identified as false negative compounds in the photohemolysis test. This in vitro method is expected to be useful as a prescreening tool for evaluating phototoxic potential of chemicals, and should be an effective means of reducing the number of animals required for phototoxicity testing.
Key words: in vitro test, photohemolysis, phototoxicity.