In-Vitro Photoxicity Assessment

We work in partnership with our clients to provide a flexible approach to phototoxicity assessment in concordance with current regulatory guidelines (EMEA; FDA). Phototoxicity may be an issue for compounds that absorb UV and/or visible radiation and are applied topically, or accumulate in the skin following administration by other routes (eg. systemic route).

Our specialist laboratory services include:

• Spectral analysis and photostability studies
  
  
• Action spectra and wavelength dependence
  
  
• Phototoxicity assessment: The ‘workhorse’ assay for in-vitro photoxicity assessment is the neutral red uptake phototoxicity assay. Spectratox can also offer supplementary assays including the photo-micronucleus assay, photo-comet assay and investigation of protein expression. Compounds can be tested in different model systems including simple monolayers; 3D co-cultures and spheroid cultures; skin equivalent models.
  
  
• Assessment of DNA reactivity: This can be an important issue for compounds that are altered by light (or their photoproducts). Model systems range from plasmid DNA to the photo-comet and micronucleus assays. Base modifications and crosslinks are identified indirectly via enzyme activity and immunofluorescence staining.

Conversely, our approach can be used in the investigation of the efficacy and ‘dark’ safety of photoactivated therapeutics under development.

in vitro phototoxicity is the ability of a compound to exhibit phototoxic properties in experimental models - usually human cell cultures.