IN VITRO TOXICOLOGY – PHOTOTOXICITY

The Biogalenys laboratory offers in-vitro phototoxicity testing in line with OCDE guideline n°432.

The in-vitro phototoxicity test 3T3 NRU relies on comparing a chemical substance’s cytotoxicity with and without exposure to a dose of non-cytotoxic simulated solar light. The test is based on measuring the cellular viability of BALB/c 3T3 cells, evaluated by reduced uptake of a vital dye, neutral red, by cells. Cell viability is measured 24 hours after exposure.

The test is based on the PIF model (Photo-irritancy Factor):

This model is based on the comparison of 2 obtained EC₅₀ values, for cytotoxicity (-UV) and phototoxicity (+UV) and makes it possible to quantify the photo-irritancy factor (PIF).

If it is not possible to quantify IC50, then the substance has no PIF.

Si PIF < 2: No phototoxicity.

Si 2 < PIF < 5: Probable phototoxicity.

Si PIF > 5: Proven phototoxicity.