Implications of Photostability on the Manufacturing , Packaging , Storage , and Testing of Formulated Pharmaceutical Products

The authors evaluate the implications of product photosensitivity and how it influences various aspects of product development. They discuss a product photosensitivity classification system and present a photosensitive pharmaceutical product case study. hotostability testing in the pharmaceutical industry has evolved rapidly, particularly since the May 1997 publication of the ICH Q1B guidance “Photostability Testing of New Drug Substances and Products” in the Code of Federal Regulations (hereafter referred to in this article as Q1B) (1). Although some notable criticisms have been leveled against the document for its perceived shortcomings (2–4), Q1B has provided much-needed input to pharmaceutical applicants about regulatory requirements for photostability testing. Significantly, Q1B alleviates much of the ambiguity around spectral range and irradiance-level requirements, harmonizes global pharmaceutical laboratory practice, and provides a sequential approach to follow when examining protective packaging requirements for photosensitive pharmaceutical products. Thatcher et al. have recently published a two-part article that provides a practical interpretation of the guideline and offers important insights into satisfying Q1B requirements (5, 6). Although Q1B identifies the need for forced-degradation photostability studies to help define method selectivity, its primary focus is to outline the confirmatory photostability testing required for drug substances and finished pharmaceutical products. Q1B is somewhat vague, however, about the experimental design and data interpretation of photostability studies, especially as they pertain to protecting photosensitive products during manufacturing, packaging, shelf storage, testing, and administration. Despite the significant lack of direction in the Q1B, the appropriate conduct of such supporting photostability studies and implementation of necessary protective measures remain an important responsibility of pharmaceutical applicants. This article summarizes important practical considerations for acquiring and using photostability data to address the effect of product photosensitivity in each critical area of product development.