FDA seeks comment on approach for defining durations of use for certain antimicrobial drugs for food animals

By David Fairfield, Senior Vice President, Feed

The U.S. Food and Drug Administration (FDA) on Jan. 8 published a concept paper to obtain input from stakeholders on a potential framework for how animal drug sponsors could voluntarily make changes to the approved conditions of use for certain medically important animal antimicrobial drugs to establish a defined duration of use for those indications that currently lack a defined duration of use.

The concept paper focuses on medically important animal antimicrobial drugs – drugs important in human medicine – administered through the medicated feed of food-producing animals. In accordance with FDA’s Veterinary Feed Directive (VFD) regulations, these drugs legally only may be used under the order and supervision of a licensed veterinarian. Currently, a limited number of medically important antimicrobials administered through animal feed include approved uses that lack a defined duration of use. Lacking a defined duration of use means that labeling for an identified product indication includes no information regarding the duration of administration or otherwise does not provide a targeted duration of use. The concept paper is limited to feed-use drugs because FDA has determined that all approved uses of medically important antimicrobial drugs in dosage forms, other than feed, already have appropriately defined durations of use. 

Currently, there are 89 approved animal drug applications for medically important antimicrobials that have one or more indications without a defined duration of use. According to FDA, these drugs comprise approximately 28 percent of all medically important antimicrobials approved for administration through animal feed. FDA states that defining durations of use for those uses of medically important antimicrobials in medicated feed that currently lack them will allow for the effective use of these products while minimizing the extent of antimicrobial drug exposure. 

The concept paper outlines a potential voluntary process that would involve drug sponsors working with FDA to make changes to the approved labeling for affected products to establish appropriately defined durations of use. FDA states that if the potential framework outlined in the concept paper later was issued as final agency guidance, implementation of that guidance would help ensure that all medically important antimicrobial animal drugs are administered in a manner consistent with ongoing efforts by the agency to limit the development of antimicrobial resistance by ensuring the judicious use of medically important antimicrobial drugs in animals.

The concept paper is intended to facilitate public comment on a potential voluntary approach to define durations of use. FDA states it will consider all information and comments received on the concept paper before issuing draft guidance for additional public comment. FDA also published a notice in the Federal Register that invites public comment on specific questions regarding the concept paper by April 12.  NGFA will be submitting such comments with input from its Feed Legislative and Regulatory Affairs and Feed Manufacturing and Technology Committees.