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# Antimicrobial Drug Duration of Use Guidance
- URL: https://www.fdaweb.com/antimicrobial-drug-duration-of-use-guidance/
- Published: 2026-02-12T12:00:00.000Z
- Updated: 2026-09-14T13:33:44.000Z
- Author: David McFarland
- Tags: FDA Policy/General, #legacy-id-D5160657

FDA has published a guidance, *Defining Durations of Use for Approved Medically Important Antimicrobial Drugs Fed to Food-Producing Animals*, to facilitate voluntary changes to have all medically important antimicrobial new animal drugs administered in alignment with the principles of judicious use. The [document](https://www.fda.gov/media/191092/download?ref=fdaweb.com) says the affected drugs are: **(1)** important to human medicine, **(2)** for use in or on the medicated feed of food-producing animals, and **(3)** currently approved with one or more indications that have an undefined duration of use.

“Establishing appropriately defined durations of use to mitigate the development of antimicrobial resistance is consistent with previous and ongoing efforts by FDA to protect public health by promoting the judicious use of medically important antimicrobial drugs in animals,” the guidance says. “This guidance provides specific recommendations on how sponsors may facilitate changes to the approved conditions of use of affected products in support of ongoing efforts to mitigate the development of antimicrobial resistance.”

The guidance contains an Introduction, Background, Scope, Objectives, Voluntary Adoption of Judicious Use Principles, Timelines for Implementing Changes, Supplemental NADAs (Pioneer Drugs), Supplemental ANADAs (Generic Drugs), Voluntary Withdrawal of Approval of a Regimen or an Indication with an Undefined Duration of Use from an NADA or Voluntary Withdrawal of the Entire (A)NADA, and Glossary.