Stability testing during drug product development

Only one batch of drug substance or drug product needs to be tested during the development phase, and then the photostability characteristics (i.e., either photostable or photolabile) should be confirmed on a single final batch. This batch should be one of the three final batches used for regulatory submission. Batch selection should be based on the criteria outlined in the parent guideline for selection of batches placed on definitive stability (32). 

Whereas the other separation methods have been demonstrated to also provide the requisite performance for release and stability testing for select drug substances and drug products, more typically the techniques are applied as supportive methods for HPLC during early-phase development and in niche areas during late-phase development. Because each separation method provides a different mechanism of separation to HPLC, utilization in early-phase development can be used to confirm specificity of HPLC methods. In later phases, both SFC and CE have shown applicability to chiral separations, and GC remains as the unique technique for the determination of residual solvents. 

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