Warnings About Cattle Antibiotic Overruled

FDA Rules Override Warnings About Drug
Cattle Antibiotic Moves Forward Despite Fears of Human Risk

By Rick Weiss
Washington Post Staff Writer
Sunday, March 4, 2007; Page A01

The government is on track to approve a new antibiotic to treat a pneumonia-like disease in cattle, despite warnings from health groups and a majority of the agency's own expert advisers that the decision will be dangerous for people.

The drug, called cefquinome, belongs to a class of highly potent antibiotics that are among medicine's last defenses against several serious human infections. No drug from that class has been approved in the United States for use in animals.


The American Medical Association and about a dozen other health groups warned the Food and Drug Administration that giving cefquinome to animals would probably speed the emergence of microbes resistant to that important class of antibiotics, as has happened with other drugs. Those super-microbes could then spread to people.

Echoing those concerns, the FDA's advisory board last fall voted to reject the request by InterVet Inc. of Millsboro, Del., to market the drug for cattle.

Yet by all indications, the FDA will approve cefquinome this spring. That outcome is all but required, officials said, by a recently implemented "guidance document" that codifies how to weigh the threats to human health posed by proposed new animal drugs.

The wording of "Guidance for Industry #152" was crafted within the FDA after a long struggle. In the end, the agency adopted language that, for drugs like cefquinome, is more deferential to pharmaceutical companies than is recommended by the World Health Organization.

Cefquinome's seemingly inexorable march to market shows how a few words in an obscure regulatory document can sway the government's approach to protecting public health.

Industry representatives say they trust Guidance #152's calculation that cefquinome should be approved. "There is reasonable certainty of no harm to public health," Carl Johnson, InterVet's director of product development, told the FDA last fall.

Others say Guidance #152 makes it too difficult for the FDA to say no to some drugs.

"The industry says that 'until you show us a direct link to human mortality from the use of these drugs in animals, we don't think you should preclude their use,' " said Edward Belongia, an epidemiologist at the Marshfield Clinic Research Foundation in Wisconsin. "But do we really want to drive more resistance genes into the human population? It's easy to open the barn door, but it's hard to close the door once it's open."

The FDA knows how hard it can be to close that door. In the mid-1990s, overriding the objections of public health experts from the Centers for Disease Control and Prevention (CDC), the drug agency approved the marketing of two drugs, Baytril and SaraFlox, for use in poultry. Both are fluoroquinolones, a class of drugs important for their ability to fight the bioterror bacterium that causes anthrax and a food-borne bacterium called campylobacter, which causes a serious diarrheal disease in people.

Before long, doctors began finding fluoroquinolone-resistant strains of campylobacter in patients hospitalized with severe diarrhea. When studies showed a link to poultry, the FDA sought a ban. But while Abbott Laboratories, which made SaraFlox, pulled its product, Baytril's manufacturer, Bayer Corp., pushed back.