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09-06-2011 | Article

Drug product labeling carries ‘information overload’


Free abstract

MedWire News: The volume of adverse drug events (ADEs) included in product labelling has increased markedly in the past few decades and is particularly high for more commonly prescribed medications as well as for psychiatric and neurologic drugs, a study shows.

Furthermore, labels that are formatted in compliance with recent labeling guidelines actually have more ADEs than other medications.

"While a high number of labeled ADEs is not necessarily indicative of a drug's true toxicity, the presence of such excess data still may induce information overload and reduce physician comprehension of important safety warnings," Jon Duke (Regenstrief Institute, Indianapolis, Indiana, USA) and colleagues comment in the Archives of Internal Medicine.

In 2006, the US Food and Drug Administration (FDA) attempted to address the issue of "overwarning" with a set of labeling guidelines, specifically discouraging the inclusion of "exhaustive lists of every reported adverse event, no matter how infrequent or minor."

Yet, at present, there are no baseline data on overwarning, nor are there benchmarks against which the success of the FDA's interventions can be measured.

In the current study, Duke et al retrieved all drug labels available on the federal website DailyMed, which provides drug data in Structured Product Labeling (SPL) format for more than 85% of prescription drugs.

Extracting more than 530,000 ADEs from 5602 drug labels, the investigators found that the median number of unique ADEs had steadily increased from 43 events per label for drugs approved in the 1960s to 63 events per label for drugs approved within the past decade.

Furthermore, almost 600 drugs listed more than 150 ADEs, and 84 listed more than 300 ADEs.

In terms of prescribing frequency, labels for the 200 most commonly dispensed medications contained significantly more ADEs than other labels (median 79 vs 47, respectively).

Aggregating drugs by medical specialty, they found the number of ADEs to be highest in medications associated with neurology, psychiatry, and rheumatology.

Labels formatted in accordance with the 2006 labeling guidelines contained a greater number of ADEs than other labels (72 vs 47, respectively).

In an accompanying editorial, Christine Cheng and Joseph Guglielmo ( University of California, San Francisco, USA) noted that, since the 2006 guidelines are not legally binding, it is not known to what extent drug labels follow these recommendations.

"At the minimum, drug labels should present ADE information in a standardized format using common terminology and definitions so that healthcare providers can systematically process and manage the deluge of clinical data," they said.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Andrew Czyzewski