New FDA Rules For Animal Drugs

Faced with growing concern about antibiotics in livestock, the Food and Drug Administration recommended a three-step process Thursday to help make sure drugs proposed for use on animals won't create dangerous drug-resistant germs.

Companies proposing new antimicrobial drugs for animal use could apply the guidelines in their applications for approval, the agency said.

In addition, officials said the FDA 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.

Antimicrobial drugs, a group which includes antibiotics, are often given to livestock to prevent illness and to encourage rapid growth. In recent years, however, worry has increased about the possibility that such routine use could encourage development of bacteria that are resistant to the drugs and those germs could then infect people.

Fast-food giant McDonald's in June urged its suppliers to phase out the use of such drugs, and in August the World Health Organization called on livestock producers to reduce drug use.

"Antibiotics have led to a transformation in the health of the population and that is why preventing antimicrobial resistance is so important," FDA Commissioner Mark B. McClellan said Thursday in announcing the guidance.

The agency said that its action is not a regulation, but noted that providing data to answer the three-step evaluation process will be a factor in considering new drug applications.

Karen Florini, a senior attorney with the interest group Environmental Defense, said the guidelines are "conceptually sound" but fail to address problems with drugs already in use.

While the FDA said it would review current drugs, there is no timetable, she noted. It could take the agency a half-century to complete the review of drugs already in use that clearly should not be allowed under the new guidelines, Florini charged. "That's just way too long to wait," she said.

Deputy FDA Commissioner Lester M. Crawford said the three parts of the evaluation of drugs 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.

Answers to those questions can be developed in the process of testing drugs before they are approved, FDA said.

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