FDA Looks to Clarify Presentation, Formatting of Drug-Drug Interaction Labeling Information

Posted 17 July 2013 | By Alexander Gaffney, RAC 

An upcoming meeting sponsored by the US Food and Drug Administration (FDA) is looking to optimize how it presents information regarding drug-drug interactions (DDIs) to the public.


DDIs refer to - as the name implies - the interaction of two or more pharmaceutical substances which, on their own, would not cause a patient harm. However, when the two products are taken simultaneously, the patient is more likely to experience an adverse side effect.

"Drug-drug interactions can lead to changed systemic exposure, resulting in variations in drug response of the co-administered drugs," FDA explains on its website. "In addition to co-administration of other drugs, concomitant ingestion of dietary supplements or citrus fruit or fruit juice could also alter systemic exposure of drugs, thus leading to adverse drug reactions or loss of efficacy."

"Therefore, it is important to evaluate potential drug interactions prior to market approval as well as during the postmarketing period," the agency added.

FDA has released extensive amounts of information on the topic, including a lengthy guidance document in February 2012 that provides recommendations for sponsors of new drug applications (NDAs) and biologics license applications (BLAs) on the studies needed to satisfy FDA's concerns about DDIs and drug-therapeutic protein interactions (DTPIs).

Among the guidance document's main points:

  • DDIs should be defined during the drug development process and their potential determined.
  • Drug development should seek to identify how the drug is activated and the role of various enzymes and transporters in that process.
  • If the potential for a DDI is identified, further testing should be conducted to collect information to quantify its effect.

An Effort to Clarify?

But despite having issued extensive guidance and other documents, there's still more to be done, FDA says in a new Federal Register posting announcing an upcoming meeting on 25 September 2013.

That meeting is set to discuss "optimal strategies for the evaluation, interpretation, and communication of DDI" through a drug's label and labeling materials, such as package inserts.

FDA said it is particularly interested in five points:

  • How DDI information should be formatted. For example, should DDI be presented using text, tables, graphs or images?
  • How much study data should be presented on the drug labeling?
  • What wording should be used when FDA has empirical data to support the likelihood of a DDI versus when it has only a vague sense that it might occur in an unknown percentage of patients?
  • What criteria should determine whether DDI derived from literature is placed on a product label?
  • How is package insert information on DDIs used to communicate safety risks or make a decision?

Additional background materials are set to be released no later than two days before the meeting, FDA's notice says.

Federal Register Notice

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