Considerations and perspectives on the practice of incurred sample reanalysis assessment for chiral drugs

Given the inherent complexities of bioanalysis, the role of incurred sample reanalysis (ISR) is increasingly appreciated in regulatory bioanalysis. Incurred sample reanalysis has evolved as an integral part of an assay to ensure method reproducibility. The current regulatory ISR guidelines do not provide clarity regarding ISR assessment for chiral drugs comprising enantiomers. Because chiral assays evaluate two enantiomers, there are additional complexities associated with the ISR data generation and interpretation. Based on the current literature, the practices for conducting ISR in chiral methods were reviewed and assessed. While ISR was conducted in chiral methods for both enantiomers using the acceptance criteria prescribed for non-chiral methods, there may be a need to streamline the nuances of ISR data interpretation and define the ISR requirements for chiral methods. The article provides perspectives on the ISR of enantiomeric drugs, including strategy development, by providing various hypothetical scenarios and possible considerations for defining ISR evaluation for chiral assays.