What is Phototoxicity
Phototoxicity - A toxic response from a substance applied to the skin which is either elicited or increased after subsequent exposure to light, or is induced by skin irradiation after system administration of a chemical.
Background - 3T3 NRU PT
The 3T3 Neutral Red Uptake Phototoxicity Assay (3T3 NRU PT) was developed and validated in a joint EU/COLIPA project from 1992-1997. In 1996, the 3T3 NRU PT was recommended by OECD as an in vitro approach for the assessment of chemicals phototoxicity potential.
In April 2004, the 3T3 NRU PT protocol was finalized and adopted as the OECD 432 protocol, In Vitro 3T3 NRU phototoxicity test.
The phototoxic potential of pharmaceutical, chemical, cosmetic and consumer products is a growing concern as the environment changes and the increased risk of sun damaged skin heightens.
Phototoxic drugs includes several common antibiotics such as tetracyclines, quinolones, and sulfonamides; tranquilizers; nonsteroidal anti- inflammatory drugs (NSAIDs); diuretics; oral diabetes medication; and cancer drugs.
Some suncreens and fragrances have also been known to have photoallergic reactions, such as Salicylates, Para-aminobenzoic acid (PABA), Musk ambrette and 6-Methylcoumarin.