Changes coming in antimicrobial use, availability

Most medically important antimicrobials used in livestock today to be affected
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When the types of antimicrobials important for human medicine are sold for use in farm animals, only a small portion require a veterinarian’s signature for purchase.

Little of the volume of such drugs sold now will be available over the counter two years from now, however.

Figures published in a report by the Food and Drug Administration show that only about 3 percent of the drugs that are both used to combat infections in humans and used in food-producing animals now require prescriptions or similar veterinary feed directives for sale. Out of 19.6 million pounds of such drugs approved for livestock use in 2012, more than 19 million pounds were shipped by pharmaceutical companies to be available over the counter.

But of that total of 19.6 million pounds, 18.4 million—or 94 percent—were distributed for use in livestock feed or water, and all uses of those antimicrobials will require veterinarian oversight or be prohibited within the next two years.

Agreements on drug use

The FDA is trying to reduce the public health threat of antimicrobial resistance by restricting livestock uses of antimicrobials that are in the same drug classes as those used in human medicine. The agency has reached agreements with 26 pharmaceutical companies to meet a December 2016 deadline to eliminate production uses—such as hastening animal weight gain—of those drugs and to remove over-the-counter access to any antimicrobials that are important for human medicine and are administered to livestock through their feed or water.

Those agreements followed agency statements in December 2013 that any pharmaceutical company that refused to make such changes could face regulatory action.

Dr. Craig Lewis, a veterinary medical officer in the FDA Center for Veterinary Medicine, said the agreement’s effects will be apparent in the FDA’s 2017 antimicrobial sales data. The FDA CVM has pushed for the changes to protect public health, and its agents are trying to minimize any negative effects on animal health, he said.

Antimicrobials administered through feed and water, shown in red, will require veterinarian oversight after 2016. Almost all antimicrobials deemed important for human medicine are currently distributed over the counter. Source: FDA 2012 summary report on antimicrobials

FDA officials also want to gather more information on antimicrobial use and antimicrobial resistance on farms, data that could be studied in combination with findings of the National Antimicrobial Resistance Monitoring System and the sales data collected from pharmaceutical companies. The agency is working with an array of federal partners to analyze impacts of changes in drug use and drug resistance, he said.

Dr. Lewis said he and others at the CVM are happy with current progress toward changing antimicrobial use, and more changes could follow.

“We really think that these represent big changes in the way that these products have been used in food-producing animals, really for decades and decades,” Dr. Lewis said. “But they probably don’t address all concerns related to the use of antibiotics in animals—in food-producing animals and animals more generally.”

Dr. Joni Scheftel, chair of the AVMA Steering Committee for FDA Policy on Veterinary Oversight of Antimicrobials, said the AVMA generally supports the changes the FDA is making, particularly regarding increased veterinarian oversight of antimicrobial use in food-producing animals.

“I think it’s fair to say that many veterinarians are looking forward to being more aware of how antimicrobials are used on their clients’ farms,” she said.

She and others on the steering committee recognize that requiring veterinary feed directives for more antimicrobial uses will be a big change for veterinarians who work with livestock. Veterinarians will face a steep learning curve, and the change also will require increased paperwork and, for some, licenses to practice in multiple states. But, she said, “AVMA members are generally supportive from all practice types.”

She also said AVMA and authorities from the FDA and Department of Agriculture plan to provide education as new regulations on veterinary feed directives are finalized.

She noted the AVMA has promoted veterinarian involvement in decisions as to whether to administer antimicrobials to animals. And she has no doubt that increased veterinarian oversight and supervision of such drug use will contribute to efforts to control the spread of antimicrobial resistance.

Dr. Scheftel thinks increased veterinarian supervision of antimicrobial use will help efforts to prevent the proliferation of antimicrobial resistance, and use will become more judicious as veterinarians become more involved, although she does not know whether overall use will decrease.

Data limitations

The FDA data do not include figures that would show the volume of antimicrobials that are important for human medicine sold for livestock production uses during 2012. As a result, the data do not indicate what volume of such drug uses will no longer be allowed, whether administered to livestock through feed, water, or other routes.

The FDA report also states that the data have limitations, most notably, that the figures show the weight of drug ingredients distributed by manufacturers rather than the weight or doses actually delivered to end users and that a “very small” but unspecified portion of the drugs distributed for use in food animals also are approved for use in pet medicine. The latter point indicates a small portion of drugs included in the report could be used in pets rather than in livestock.

In addition to the 19.6 million pounds of antimicrobials that are in drug classes important for human medicine, the FDA data show that pharmaceutical companies distributed another 12.6 million pounds of antimicrobials not considered important for human medicine, all of which are distributed for over-the-counter availability.

Related JAVMA content:

FDA restricting antimicrobial uses in livestock (Jan. 15, 2014)