Rockville, Md.-The Food and Drug Administration's (FDA) plan to curb antibiotic resistance through greater controls on veterinary
drugs is being met with some opposition from industry groups.
Dr. Linda Tollefson
At presstime, the American Veterinary Medical Association (AVMA), the Animal Health Institute (AHI) and various agriculture
groups were formulating formal positions that will be submitted to FDA's Center for Veterinary Medicine (CVM) on Nov. 27.
The positions are in response to new risk assessment guidelines that will be considered when approving a new, or existing,
antibiotic for use in agriculture. Consumer groups plan to formulate opinions on the subject too, and contend the agency is
not going far enough to control antibiotic use in agriculture.
The guidelines are the agency's attempt to add a new safeguard to combat antibiotic resistance.
The document outlines a detailed risk assessment methodology used on antibiotics prior to FDA approval for use in agriculture.
The agency also plans to apply this risk assessment to already approved veterinary antibiotics, Dr. Linda Tollefson, deputy
director of FDA's Center for Veterinary Medicine, tells DVM Newsmagazine.
The draft guideline summarizes the issue this way: "The FDA believes that human exposure through the ingestion of resistant
bacteria from animal-derived foods represents the most significant pathway for human exposure to resistant determinants (or
resistant bacteria) that have emerged as a consequence of antimicrobial drug use in animals."
Dr. Lyle Vogel
The long-term impact of this guidance is unclear, officials say. Uncertainty breeds fear. A shift from approving antibiotics
over-the-counter to a prescription or veterinary feed directive classification is most likely imminent for new and possibly
One risk management strategy identified by FDA is to possibly prohibit extra-label use of veterinary drugs in certain circumstances,
which is of great concern to the AVMA.
And while this guidance document is squarely focused on food animals, every veterinary practitioner from companion animal
to equine, should take notice, says Dr. Lyle Vogel, director of scientific activities for the AVMA.
"Looking at scientific reports it is becoming evident that there is a potential there that resistant bacteria are being transferred
between companion animals and humans, and possibly in both directions. The public health authorities and regulators are going
to start looking at that if it appears to be a significant risk."
Risk assessment is needed
FDA says that adding a risk assessment strategy is needed to help safeguard human health and keep these drugs effective for
"Minimizing the risk of antimicrobial resistance is in the best interest of everyone," Tollefson says.
She explains this risk assessment process is necessary to keep new products coming to market. She adds that the likely outcome
of having a formal process in place to assess the risks of resistant pathogens impacting humans through the use of antibiotics
for agriculture will actually help spur approvals by adding new safeguards to the system.
Industry couldn't disagree more.
Dr. Tom Burkgren, executive director of the American Association of Swine Veterinarians, fears that products will be lost
to veterinarians and producers as a result. Vogel also thinks agriculture will lose some antibiotics.
Burkgren explains: "Overall, there is such a high degree of subjectivity built into the guidance document, the devil is really
going to be in the details. How they apply this guidance is key. They could be very flexible in their application of this,
or they could take a more draconian method and apply it very restrictively. The result could be they stop approving drugs,
and we could have current drugs approval removed or labels changed. That is our fear," he says.
Even more ominous could be the response from manufacturers, which could impact all areas of the veterinary profession.
"I think there are going to be products that will not be defended," Burkgren says. "I think the higher volume, low margin
products will not be defended. And all we will be left with are the high margin, low volume products," he adds.
What classes of antibiotics are at greatest risk to agriculture? Fluoroquinolones, growth promotants and any antibiotic used
in feed or water for more than six days in duration are all at risk for FDA intervention, he adds. There is already FDA action
to remove Baytril from the poultry market, as reported in DVM Newsmagazine, but manufacturer Bayer is contesting the move
Tollefson adds that FDA is committed to the protection of animal health too, and did most recently approve an entirely new
antibiotic compound, danofloxacin mesylate, for Pfizer for treatment of bovine respiratory disease in beef.
But for swine practitioners, removing the ability to medicate from a population-based (metaphylaxis) method is very significant
to modern agriculture.
Air it in public
At presstime, FDA convened a public meeting to gather input on the proposed draft guidance for industry entitled, "Evaluating
the Safety of Antimicrobial New Animal Drugs with Regard to their Microbiological Effects on Bacteria of Human Health Concern."
About 150 people were in attendance, CVM reports.
Tollefson says that the agency will take all this information into consideration and a final guidance will be issued tentatively
slated for the spring of 2003.
FDA says: "Risk: FDA's overriding concern is that the effectiveness of antimicrobial drugs is decreased or lost in humans
as a consequence of human exposure to resistant bacteria (or resistant determinants) resulting from the use of antimicrobial
drugs in food-producing animals."
The new guidelines outline a risk analysis methodology as a "process for evaluating antimicrobial resistance concerns as part
of the pre-approval safety evaluation of a new animal drug. These guidelines also allow the agency to review existing antibiotics
on the market to re-evaluate the potential for causing antimicrobial resistance.