Drugmakers should evaluate a product’s UV-visible absorption spectrum before starting clinical development, the ICH says in a new guideline that will standardize photosafety testing standards across the EU, Japan and U.S.
The initial test simply determines whether risk minimization measures are needed to prevent adverse, light-induced tissue reactions to a photoreactive chemical, and it can establish that there is no need for further photosafety evaluation, the International Conference on Harmonisation’s (ICH) S10 guideline states.
The final ICH S10 guideline, released Jan. 7, provides specific guidance on testing strategies for new active pharmaceutical ingredients, new formulations of excipients for dermal applications and photodynamic therapy products, including guidance on when testing is warranted.
Once an initial assessment determines a material needs further phototoxicity assessment, sponsors must develop their strategies for in vivo, in vitro or small clinical studies to further understand the photosafety of the drug before testing it on a larger number of patients in outpatient studies.
The guideline says the following characteristics are critical for demonstrating phototoxicity:
The material absorbs light within the range of natural sunlight;
The material becomes a reactive species following absorption of UV-visible light; and
The material distributes sufficiently to light-exposed tissues such as skin and eyes.
The EMA in 2012 adopted the draft ICH S10 guideline. The FDA last year followed suit with its own draft guidance, which states photostability testing alone is not enough to identify phototoxic starting materials.