The ICH Q1B Guideline was finalized in November 1996. This guidance details the principles required to evaluate the light sensitivity and stability of new drug substances and products. Q1B has been adopted/published/implemented by noteworthy institutions including EC (Europe), MHLW/PMDA (Japan), FDA (US), Health Canada (Canada) and Swissmedic (Switzerland). This guideline primarily addresses the generation of photostability information for submission in Registration Applications for new molecular entities and associated drug products. In the guideline, a systematic approach to photostability testing is recommended as well as light sources and procedures. A suggested decision flowchart for photostability testing is shown below.
The recommended testing for drug substances and drug products were both provided in the Q1B Guideline, including preparation of samples, analysis of samples and methods for evaluating results. For drug substances, photostability testing should consist of forced degradation testing and confirmatory testing. For drug products, studies should be carried out in a sequential manner starting with testing the fully exposed product then progressing as necessary to the product in the immediate pack and then in the marketing package.
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