Abstract
INTRODUCTION: The purpose of the present study was to investigate the traceability of adverse events (AEs) for branded and generic drugs with identical nonproprietary names and to consider potential implications for the traceability of AEs for branded and biosimilar biologics. METHODS: Adverse event reports in the Food and Drug Administration AE Reporting System (FAERS) were compared with those in a commercial insurance claims database (Truven Health MarketScan(®)) for 2 drugs (levetiracetam and enoxaparin sodium) with manufacturing or prescribing considerations potentially analogous to those of some biosimilars. Monthly rates of branded- and generic-attributed AEs were estimated pre- and post-generic entry. Post-entry branded-to-generic AE relative rate ratios were calculated. RESULTS: In FAERS, monthly AE rate ratios during the post-generic period showed a pattern in which AE rates for the branded products were greater than for the generic products. Differences in rates of brand- and generic-attributed AEs were statistically significant for both study drugs; the AE rate for the branded products peaked at approximately 10 times that of the generic levetiracetam products and approximately 4 times that of the generic enoxaparin sodium products. In contrast, monthly ratios for the MarketScan data were relatively constant over time. CONCLUSION: Use of the same nonproprietary name for generic and branded products may contribute to poor traceability of AEs reported in the FAERS database due to the significant misattribution of AEs to branded products (when those AEs were in fact associated with patient use of generic products). To ensure accurate and robust safety surveillance and traceability for biosimilar products in the United States, improved product identification mechanisms, such as related but distinguishable nonproprietary names for biosimilars and reference biologics, should be considered.