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New Guidance for Industry on Antimicrobial Drugs for Food Animals
Questions and Answers

What drugs are you talking about? What’s an antimicrobial? Can you give me examples?

This document would be used to evaluate drugs for use in food-producing animals that are used to treat infections caused by bacteria. Bacteria are living, single cell organisms. They should not be confused with viruses, which can also make humans and animals sick, but are not treated with antibiotics. Some common examples of antibiotics that are used for animals and humans are penicillin and oxytetracycline.

What is an antimicrobial? Is it different than an antibiotic?

An antimicrobial is a broader class of bacteria-killing or inhibiting products that includes antibiotics. The biggest difference between the two classes is that antibiotics are produced from living microorganisms like fungi Antimicrobial also include synthetic products that can also be used to kill or inhibit the growth of bacteria.

What involvement do FDA and CVM have with animal drugs?

FDA has responsibility for determining the safety of food as well as drugs. Drugs are frequently used for animals the same way they are used in people – to treat illness and improve the health of the animals. Drugs are used in animals that are used as human food, such as cows, pigs, chickens, fish, etc., and these drugs can affect the safety of the meat, milk, and eggs produced from those animals. Therefore, FDA has the responsibility to review drugs intended for use in food animals, and to be sure that the use of the drugs does not result in harmful residues in food or create resistant pathogens that can harm human health. Within FDA, the animal drug review duties have been assigned to one of the Agency’s operating units, the Center for Veterinary Medicine.

How does this guidance work?

The guidance is presented as a tool for animal drug sponsors to use to help provide information to FDA showing that an antimicrobial drug can be used to treat animals without fostering the development of resistant bacteria that create a threat to public health. The key to the guidance is a qualitative risk assessment. The drug sponsor uses data to determine, first, what is the probability of the antimicrobial drug fostering the development of resistant bacteria in the animals being treated; second, what is the possibility of human being ingesting the resistant bacteria;and, third, what is the possibility of the ingestion of the resistant bacteria will result in human health concerns.

You say FDA can deny the approval of an antimicrobial drug if the risk estimation is “high.” What’s high?

A “high” score means that the use of the particular antimicrobial would likely lead to adverse human health consequences.

The guidance document would assign each of the three steps listed above a score of low, medium, or high risk. If an antimicrobial drug was likely to foster the development of resistant bacteria in the treated animals, humans were likely to ingest the resistant bacteria, and the ingested bacteria were likely to cause an infection that would result in human health concerns, the drug would be given a high risk score, and FDA might take a range of risk management actions from denying the approval of the new animal drug application, to approving the application with various conditions of use that assure the safe use of the product.

If the risk assessment score turned out medium, FDA could place more limited risk management constriction on the use of the drug. And if the score was low, even fewer risk management conditions would be needed.

Why are you presenting this information to the animal drug industry? Doesn’t FDA test drugs to see whether they are safe?

FDA does not normally do the actually testing of safety and effectiveness of drugs. Typically, the company that wants to market the product does the required testing , and FDA audits and evaluates the results and then determines independently whether the demonstrated benefits of the drug outweigh the known risks for the intended uses of the product. With drugs intended to be used in food producing animals, the drug company must prove to FDA’s satisfaction with scientific data that the drug will not cause human health concerns in order for FDA to allow the product on the market.

Will FDA apply this risk assessment to all new animal drugs presented to it? Do you expect drug sponsors to conduct the risk estimation?

The Guidance is recommended only to evaluate antimicrobial products submitted for FDA review for use in food-producing animals. Again, the guidance is only one approach for evaluating the safety of antimicrobial new animal drugs. Alternative approaches may also be used by the drug sponsor.

Is this Guidance recommended to all types of animal drugs?

No, just antimicrobial drugs for use in animals that produce food.

What is a drug sponsor?

A drug sponsor is a company that has either developed a new drug product or acquired the rights to one and is seeking FDA approval to market the product in the United States. Typically, the drug sponsor is a pharmaceutical company, but it can be a marketing company or even an individual.

Can this guidance be used to evaluate subtherapeutic use of drugs? How about drugs used for growth promotion? What about for genetically engineered drugs?

This guidance can be used to evaluate all types and uses of antimicrobials, including what some refer to as subtherapeutic use. Although that term has not been defined by regulation, it describes the use of a product to boost an animal’s ability to grow and produce more food, instead of treating or preventing an infectious disease. So, yes, the guidance could be used to evaluate subtherapeutic use of antimicrobials. It could also be used to evaluate antimicrobials if they are used for growth promotion, and for antimicrobials that are products of genetic engineering.

What is a food-producing animal?

Animals that we use to produce food for human consumption, including cows (for beef and milk production), pigs, chickens, turkeys, fish, and sheep.

Who is a food-animal producer?

A food-animal producer is an individual or company that grows animals such as cows, pigs, and poultry, for use as food animals.

What do you mean when you say in the press release “livestock production purposes?”

That phrase applies to the use of antimicrobials to cause animals to increase production of food. Antimicrobials are used in feeds for some species, and the animals fed the antimicrobial feeds often grow faster while consuming less feed than animals not given antimicrobials in feed.

Why is this just a guidance? What happens if a drug company doesn’t follow the guidance?

This is a guidance because FDA is not requiring any specific action from drug sponsors. Rather, FDA is using this document to help drug sponsors understand the FDA’s present thinking on one way to meet the requirements of existing regulations.

The existing regulations say that FDA must be sure that a drug product is safe before the Agency can permit the drug to be marketed. In addition to determining whether the use of a drug would result in residues left in the meat, milk, or eggs, FDA must ensure that the use of antimicrobials in food-producing animals does not lead to the development of resistant bacteria that can become a public health concern. This document is one way that drug sponsors can submit information that address the issue of the microbial safety of antimicrobial new animal drugs. A sponsor is free to use other scientifically valid approaches to demonstrate the safety of their proposed product.

Why did it take so long to do this?

CVM first said in December 1999 that it would consider the question of the fostering of antimicrobial resistance when reviewing antimicrobials for use in animals. That announcement was followed a year later with what was called FDA’s “Framework Document,” which first described the FDA’s plan to use risk assessments of the development of antimicrobial resistance in determining the safety of antimicrobials for food-producing animals. The guidance document was first published as a draft in September 2002, to allow the scientific community to comment on the concept and on the science FDA used to develop the guidance document. Comments have been evaluated and used to finalize CVM’s guidance document.

Why do we allow antibiotics in food animals?

We allow the use of antimicrobials because they are a valuable tool that veterinarians can use to treat sick animals, and so livestock producers can use antimicrobials to produce meat, milk, and eggs more efficiently.

The science of determining risk from antimicrobials is constantly improving and expanding. As more information becomes available, FDA uses it to help make the appropriate public health decisions.

Now that the guidance is in place, will you use it to evaluate drugs already on the market, or will its use be limited to new drugs submitted for your approval?

We are evaluating drugs currently on the market for their potential to cause a human health concern because of antimicrobial resistant bacteria.

What will this guidance do about labeling on food products? Will food in the grocery store explain whether the animal was produced with or without the use of antimicrobials?

The guidance has nothing to do with food labeling. It contains no provision calling for labeling of meat (or other products from food producing animals) as to whether it was produced with antimicrobials.


Press Release
Guidance Document (PDF)
Antimicrobial Guidance Slides
Federal Register (PDF)

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