Two months after the U.S. Food and Drug Administration (FDA) put out a voluntary plan intended to mollify both sides in the debate over administering antibiotics to livestock that are not clinically ill, a federal judge’s ruling eventually could force the agency to launch formal hearings on the issue.

In a June 1 opinion, U.S. Magistrate Judge Theodore H. Katz of the Southern District of New York found that the FDA had in November 2011 unlawfully denied two citizen-led petitions that asked the agency to launch withdrawal proceedings for non-therapeutic uses of medically important antibiotics in livestock. The petitioners, a coalition of environmental and public health advocacy groups, defined “non-therapeutic” to include growth promotion as well as many common disease prevention uses. 

Basic biology indicates that low doses of antibiotics generate antibiotic-resistant microbes, but the risk these pathogens pose to human health has not been well quantified. 

Katz found that the FDA’s decision to dismiss the petitions, filed in 1999 and 2005, was “arbitrary and capricious” because the FDA did not provide evidence of the safety of the antibiotic practices the petitioners sought to stop. The ruling does not directly compel the agency to launch withdrawal hearings, but it does force a reconsideration of the petitions.

The June 1 ruling reinforces a related decision issued on March 22 by Katz, in which he ordered the FDA to restart withdrawal hearings initiated in 1977 to evaluate the safety of using penicillins and tetracyclines to fatten livestock. The FDA filed an appeal of that decision May 21.

The FDA plan, issued in April, would phase out the growth promotion label for classes of antibiotics that are used in human medicine. It also would require veterinary oversight of all uses of antibiotics in livestock. Currently, livestock producers can buy antibiotic-supplemented feed to promote growth or prevent disease in their herds and flocks without contacting a veterinarian.

The FDA currently labels livestock antibiotics for four uses: disease treatment, disease control, disease prevention and growth promotion.

While the FDA plan is voluntary, pharmaceutical companies have indicated that they plan to comply with the drug-labeling changes the agency recommends.

It is unclear how the FDA’s proposed veterinary oversight provisions will change antibiotic use practices on U.S. farms. Public health and environmental groups argue that the rules would have little effect because drug companies will be able to apply to have antibiotics now sold for growth promotion relabeled for disease prevention. The FDA plan states that the agency would facilitate such relabeling, and the Animal Health Institute (AHI), a coalition of pharmaceutical companies, indicates on its website that it believes antibiotics currently sold for growth promotion uses would qualify for a disease prevention label: “Both experience and the progression of science since these growth claims were first introduced strongly indicate that doses lower than treatment doses do prevent disease in animals.”  

After Katz’s ruling, AHI issued a statement saying the decision “adds confusion to FDA’s efforts to phase in veterinary oversight of antibiotics used in food animals while eliminating growth promotion uses.”

The prevalence of growth promotion and disease prevention uses of antibiotics is unclear because the federal government does not collect data on the quantities of antibiotics sold for those purposes versus for the control and treatment of disease. Livestock veterinarians say that modern livestock operations are, as a rule, substantially more dependent on disease prevention uses of antibiotics than on growth promotion uses. Disease prevention antibiotics include such products as Tylosin, a macrolide widely fed to beef cattle to prevent liver abscesses associated with grain-heavy feedlot diets.

The FDA contended that its voluntary plan would be a more efficient way to achieve a result similar to what the citizen petitions seek. Katz rejected that argument on several counts. He found that the existence of the voluntary plan did not excuse the agency from giving due consideration to the petitions and, if necessary, launching drug withdrawal proceedings. Further, he found that the FDA had not adequately addressed the petitioners’ concerns about the safety of antibiotics used for disease prevention:

“The agency did not respond to the petitioner's claims that the use of the indicated antibiotics for general disease prevention was not shown to be safe and did not provide any explanation for its decision to allow the continued use of these drugs for that purpose. This failure to explain the agency's decision-making is arbitrary and capricious.”

The FDA may appeal Katz’s latest decision. A court timeline has not been set for the agency’s appeal of his March 22 ruling.