Consistency in the safety labeling of bioequivalent medications

Purpose Bioequivalent medications are required by the Food and Drug Administration to have identical warnings on their labels. This requirement has both clinical and legal importance, yet has never been validated. We sought to determine the real-world consistency of electronic labeling for bioequivalent drugs from different manufacturers. Methods Using natural language processing, we indexed the adverse drug reactions (ADRs) found in the Adverse Reactions and Post-Marketing sections of 9105 structured product labels. We calculated the standard deviation in ADR labeling for each bioequivalent drug and the percent deviation of each generic label from its corresponding brand. We also analyzed the performance of individual generic manufacturers. For the 25 drugs with the greatest discrepancy in labeled ADRs, we performed manual review to identify causes of inconsistency. Results 68% of multi-manufacturer drugs had discrepancies in ADR labeling. For a given drug, the mean deviation in number of labeled ADRs was 4.4, and the median was 0.8 (IQR 0 to 3.2). The mean range in number of labeled ADRs was 12 +/ 0.9, and the median was 2 (IQR 0 to 9). Overall, 77.9% of generic manufacturers produced labels differing from brand. Causes of inconsistency included missing tables, outdated post-marketing reports, and formatting issues. Conclusions Despite FDA mandate, bioequivalent drugs often differ in their safety labeling. Physicians should be aware of such differences and regulators should consider new strategies for harmonizing bioequivalent labels. Copyright (c) 2012 John Wiley & Sons, Ltd.