Inconsistent excipient listings in DailyMed: implications for drug safety

Excipients, or inactive ingredients, are a frequent cause of medication intolerance and allergy. Patients and clinicians concerned about medication allergies and sensitivities rely on the U.S. National Library of Medicine's DailyMed for accurate lists of excipients. Based on our anecdotal discovery of several examples of excipient omissions, we wished to examine the accuracy of DailyMed's listings more systematically in a sample of commonly prescribed medications. The objective of the study is to identify the frequency of inconsistency of excipient reporting within the DailyMed website. We performed a database audit of the Structured Product Labeling XML file provided by the drug manufacturer to the Food and Drug Administration and DailyMed for two randomly selected formulations of each of 50 commonly prescribed medications. For each of the 100 formulations, we compared the excipients listed in the "Description" to those in the "Ingredients and Appearance" sections in DailyMed. The Structured Product Labeling data file provided by the drug manufacturer contained internal inconsistencies of excipients in 39% of the formulations examined. Despite the use of Structured Product Labeling, the drug manufacturer's medication labels provided to the FDA and reported by DailyMed often contain conflicting information about inactive ingredients. Patients with allergies and excipient sensitivity should be aware of these discrepancies and consult multiple sections of the label to identify potential allergy-inducing inactive ingredients.