(T1130-09-49) Bioanalytical Considerations in ANDAs with Analyte(s) as Endogenous Compounds Based on Commonly Observed Deficiencies

Purpose: This project is to underscore challenges and appropriate approaches in the analyses of in vivo levels of drugs that also exist endogenously in the pharmacokinetic (PK) studies of Abbreviated New Drug Application (ANDA) submissions for generic drug products.

Methods: In order to collect and summarize common deficiencies identified in assessments on the bioanalytical part of the ANDA submissions of ten drugs that also exist endogenously. Bioequivalence (BE) assessments of all the in-house ANDAs received for such drug products from 2006 to 2021 were collected and deficiencies related to general bioanalytical approach were evaluated; specifically, those associated with bioanalysis of drug moiety were sorted.

Results: The results show that approximately 50% of all the bioanalytical deficiencies identified during ANDA assessments were specifically due to the target analytes being endogenous. In BE assessments of ANDAs collected, the predominant deficiencies were related to the inappropriate preparation of calibration standard (CS) and quality control (QC) samples followed by lack of parallelism studies when surrogate matrix is employed. For accurate measurement of such analytes in human matrices, strategies are required not only to account for endogenous levels but also to prepare relevant CS and QC samples. The most common challenges seen in BE assessments are of having analyte free matrix (plasma stripping may not be consistent) or selection of appropriate surrogate matrix for preparation of CSs with comparable matrix effect to original matrix (parallelism), reliable estimation of baseline levels and choice of QC concentrations, particularly LQC due to baseline level adjustment when endogenous levels are high. Out of all the bioanalytical deficiencies, 28% were regarding general bioanalytical issues related to evaluation of cross analyte interference, inconsistent recovery, long term stability studies in relevant matrix, run rejections etc. While the remaining of the deficiencies were identified such as incomplete documentation, i.e., missing analytical method specific standard test procedures. Deficiencies collected were further evaluated to propose the critical steps to be considered during bioanalysis.

Conclusion: This project summarizes bioanalytical deficiencies with ANDA submissions received by the Agency for endogenous drugs and identifies commonly used approaches for accurate measurement of in vivo levels for such drugs in BE studies such as charcoal stripping of matrix, use of surrogate/diluted matrix, or depleting the endogenous analyte by light exposure in case of photosensitive analyte and associated bioanalytical considerations for each approach. The outcome of this project emphasizes consideration of important aspects of bioanalytical method during validation including, but not limited to, use of appropriate matrices, screening of pooled matrix having low endogenous levels, method of CSs and QCs preparation, pre-dose drug level measurement, parallelism studies etc. Overall, this project should provide industry with further guidance as to avoid unnecessary bio-analytical deficiencies for such drug products, improving the overall quality of ANDA submissions, and thus avoiding the multiple cycles of review. This will greatly benefit the American public as it will lead to early availability of the generic drug products.