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Faced with growing concern about the use antibiotics in livestock, the Food and Drug Administration has released a guidance document recommending a three-step process to combat potential antimicrobial resistance in humans.

Animal health companies proposing new antimicrobial drugs for animal use could apply the guidelines in their applications for approval.

In addition, FDA officials will use the guidance to evaluate antimicrobials already in use, and could move to take them off the market if it determines there is a risk to humans.

"Antibiotics have led to a transformation in the health of the population and that is why preventing antimicrobial resistance is so important," says Mark B. McClellan, FDA commissioner.

The new guidance encourages drug sponsors to use a risk assessment process to demonstrate that an antimicrobial drug used to treat food-producing animals will not create a risk of antimicrobial resistant bacteria likely to lead to human health problems.

The document, Guidance for Industry #152 ("Evaluating the Safety of Antimicrobial New Animal Drugs with Regard to their Microbiological Effects on Bacteria of Human Health Concern"), is not a regulation. Instead it explains a science-based process drug sponsors may use when they seek approval of an antimicrobial for use in food-producing animals.

The three parts of the drug evaluation are:

  • A "release assessment," which determines the probability the use of an antimicrobial drug will result in development of resistant bacteria in an animal.
  • An "exposure estimate," which estimates the likelihood that, if such bacteria did develop, people would ingest them.
  • The "consequence assessment," which evaluates whether humans would be harmed if they were exposed to such bacteria.

Linda Tollefson, deputy director of the FDA's Center for Veterinary Medicine, says the agency gets about 10 applications for new animal antimicrobials per year, and receives many applications to allow new uses for current drugs.

More information is available online at www.fda.gov/oc/antimicrobial/questions.html.