Testing frequency drug product stability

For long-term studies, frequency of testing should be sufficient to establish the stability profile of the drug product. For products with a proposed shelf life of at least 12 months, the frequency of testing at the long-term storage condition should normally be every 3 months over the first year, every 6 months over the second year, and annually thereafter through the proposed shelf life. 

The FDA Draft Stability Guidance, which predates the ICH Draft Revised Guidance, sdoes not provide testing frequency for intermediate studies or accelerated studies for API. It indicated a minimum of four test stations (e.g., 0,2,4, and 6 months) for accelerated studies for drug products. 

Specifications and Test Methods Storage Conditions Testing Frequency Stability Commitments Data Evaluation DRUG PRODUCT... 

The frequency of testing of an intermediate s stability is related to the length of the holding time. Where practical, testing should be done at a minimum of three time points after the initial testing of an intermediate. At a minimum, all critical parameters should be evaluated at release of an intermediate and immediately before its use in the manufacture of the finished drug product. 

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