Implications of In-Use Photostability: Proposed Guidance for Photostability Testing and Labeling to Support the Administration of Photosensitive Pharmaceutical Products, Part 3. Oral Drug Products.

The ICH Q1B guidance and additional clarifying manuscripts provide the essential information needed to conduct photostability testing for pharmaceutical drug products in the context of manufacturing, packaging, and storage. As the previous 2 papers in this series highlight for drug products administered by injection (part 1) and drug products administered via topical application (part 2), there remains a paucity of guidance and methodological approaches to conducting photostability testing to ensure effective product administration. Part 3 in the series is presented here to provide a similar approach and commentary for photostability testing for oral drug products. The approach taken, as was done previously, is to examine "worst case" photoexposure scenarios in combination with ICH-defined light sources to derive a set of practical experimental approaches to support the safe and effective administration of photosensitive oral drug products.