posted by admin on 22/03/06
WASHINGTON -- Federal regulators, in another sign of the growing concern over a possible avian-flu pandemic, moved to ban the poultry industry from using two major groups of human antiviral drugs to treat their flocks, for fear that may reduce their effectiveness in treating humans.
The Food and Drug Administration said beginning this summer, it is proposing to prohibit veterinarians from prescribing off-label, nonhuman uses of Roche Holding AG's Tamiflu and GlaxoSmithKline PLC's Relenza; amantadine (used in generics such as Symmetrel by Endo Pharmaceuticals Holdings Inc.) and rimantadine (used in Flumadine, by Forest Laboratories Inc.). The government has been stockpiling some drugs to prepare for a possible avian-flu outbreak in humans.
Not one of those drugs is approved for use in animals, but under a 1994 law, the FDA allows veterinarians to prescribe them as such. But the law gives the FDA the right to ban them if they cause public-health concerns. Yesterday's announcement marked the first time that the FDA has banned human antiviral drugs for animal use.
The FDA and the U.S. poultry industry say these drugs haven't been used in poultry here yet. They are often more expensive than the cost of the birds they would treat. But last year, China used one of the drugs to treat flocks; this action caused resistance to the drug by an avian-influenza strain, said Stephen Sundlof, director of the FDA's Center for Veterinary Medicine. International agencies, such as the World Health Organization and the Food and Agriculture Organization, have called for the ban to prevent the development of resistant strains.
Dr. Sundlof called the move a precautionary measure. "This is just to put everybody in notice that that particular practice is prohibited by law." He expects the proposal, which is open to public comment until May 22, will become a final rule June 30.
The announcement follows the agency's decision last year to ban, for the first time, an antibiotic used in chickens and turkeys. At that time, the FDA cited evidence that use of the antibiotic might lead to pathogens that could withstand drugs used to fight human illness. The agency's reasoning for yesterday's move on antiviral drugs sprang from similar concerns about resistant strains. Because influenza viruses mutate frequently, resistance to antiviral drugs can leave doctors with fewer choices for treatment.
The FDA ban is part of a broad campaign by the Bush administration to convince the U.S. public that it is preparing for the appearance of the deadly Asian strain of H5N1, which several officials have said could arrive in Asian birds migrating to Alaska as early as this spring. Finding the Asian strain of H5N1 in wild U.S. birds is "increasingly likely," said Interior Secretary Gale A. Norton.
At a briefing by three cabinet secretaries, the administration heralded an "early warning system" it has set up to test up to 100,000 wild birds this year in Alaska and the Pacific Coast flyway, believed to be where the avian flu might show up in the U.S. first, given migratory patterns. The government plans to collect about 50,000 samples of water and bird feces from waterfowl habitats.
The Agriculture Department allows the poultry industry to use vaccine to treat some viral-respiratory diseases, but the poultry industry generally kills the infected flocks to prevent diseases from spreading. The chicken industry has vowed to test all flocks for avian flu before sending them to the market, and destroy those infected with some strains, said Richard Lobb, spokesman for the National Chicken Council, a Washington trade group.
Margaret Mellon, director of the Food and Environment Program at the Union of Concerned Scientists in Washington, applauded the FDA's decision. "The industry might be tempted to use these drugs until the agency simply acts early and preventively to prevent this from happening," she said.
Terence Hurley, spokesman for Roche, says the company has heard of isolated cases of Tamiflu being used in cats and dogs, but not in poultry. "Roche fully support FDA's decision," he said. Tamiflu is approved for use in people, not animals."
Michael Fleming, a spokesman for GlaxoSmithKline, says the company hasn't studied the impact of Relenza, an inhaled product, on animals, and it supports the FDA decision.
Forest Laboratories and Endo Pharmaceuticals Holdings declined to comment.