Phototoxicity & Photoallergy
Introduction to Photosafety
Compounds that absorb in the UV/visible light spectra and are applied or distribute to sun-exposed areas, like skin and eyes, are candidates for photosafety evaluation. These compounds may become more toxic or reactive after exposure to sunlight. Systemically administered compounds such as pharmaceuticals, and topically applied compounds such as cosmetics, fragrances, and personal care products...
UV-Vis Analysis
One of the first steps in a photosafety assessment is determination of the absorption spectrum of a test compound. A compound that absorbs sufficient light in the UV and visible light range will be a candidate for further photosafety testing. The amount of absorption is referred to as molar extinction coefficient (MEC). The MEC is...
3T3 Phototoxicity (OECD 432)
The 3T3 Neutral Red Uptake (NRU) Phototoxicity assay is a 96-well cytotoxicity-based assay that utilizes BALB/c 3T3 mouse fibroblasts to measure the concentration-dependent reduction in neutral red uptake by the cells after exposure to a test material in the presence and absence of UVA light. Duplicate 96-well plates containing a monolayer of 3T3 cells are...
In vitro Phototoxicity – Reconstructed Human Epidermis Phototoxicity test (OECD 498)
The 3-D Phototoxicity assay uses reconstructed human epidermal (RhE) tissue constructs to evaluate the dermal phototoxicity potential of a test material. Toxicity is determined by measuring cytotoxicity [based on the relative conversion of MTT (3-[4,5 – dimethylthiazol-2-yl] – 2,5 – diphenyltetrazolium bromide)] in cultures treated with the test material in the presence and absence of UVA...
Photo-Direct Peptide Reactivity Assay
The in chemico photo-DPRA incorporates a light exposure step into the standard DPRA protocol to determine if a compound becomes photoreactive in the presence of light. Peptide depletion is measured after exposure to a compound in the presence and absence of UVA/visible light. In addition, because the assay includes a standard 24 hour exposure without...
Photo-KeratinoSens
The ARE-Nrf2 Luciferase Keratinocyte Activation Test Method (OECD 442D) is used to evaluate induction of ARE-specific genes after exposure to a skin sensitizer. IIVS is examining a modified photo-KeratinoSens™ assay, which incorporates a light exposure step (5J/cm2), to evaluate the photoallergy potential of test materials. Twelve concentrations of a test material are evaluated in the...