020263 FDA Hearings on Animal Antibiotic Ban

Washington - The US Food and Drug Administration (FDA) is planning to hold an administrative hearing to consider the forced withdrawal of an animal antibiotic manufactured by the Bayer Corporation, because the agency says it poses a threat to human health.

Called Baytril, Bayer's antibiotic is from the fluoroquinolone class of antibiotics. It was the first fluoroquinolone specifically developed for animal use, and initially was approved by the FDA in 1989 for the treatment of certain bacterial infections in dogs.

As a fluoroquinolone, it would be equivalent to human antibiotics such as Bayer's anthrax treatment Cipro (ciprofloxacin).

If Bayer loses and the FDA commissioner subsequently decides to force the withdrawal, it would be the first such case of forced withdrawal of an animal antibiotic in the US due to the threat it may pose to human health.

In a notice issued late Wednesday, the FDA said the hearing would focus on an October 2000 proposal by its Center for Veterinary Medicine (CVM) to ban the use of all fluoroquinolones for the treatment of poultry.

"In its October 2000 proposal, CVM said the use of fluoroquinolones in poultry causes the development of fluoroquinolone-resistant Campylobacter bacteria in poultry, and that these fluoroquinolone-resistant Campylobacter bacteria are transferred to humans and cause the development of fluoroquinolone-resistant Campylobacter in humans," the FDA explained. "Further, CVM said, fluoroquinolone-resistant Campylobacter infections in humans are a health hazard."

Campylobacter is a type of bacteria believed to be the most common cause of human food poisoning.

Deputy Director of the FDA's Center for Veterinary Medicine Dr. Linda Tolefson said that the agency estimates about 10,000 cases of fluoroquinolone-resistant Campylobacter infections occur each year in the US based upon case reports, research and epidemiological studies.

Although fluoroquinolones are not considered the first treatment option for Campylobacter, Tolefson added that fluoroquinolones are often used as the first drug of choice because Campylobacter cannot be distinguished from Salmonella, another serious form of food-borne pathogen.

Officials from Bayer did not return requests for comments.

But in February 2001, Bayer filed a report with the FDA concluding that the CVM analysis was flawed.

"There is no evidence that withdrawal of the product would have a meaningful impact on resistant Campylobacter infections in humans," the company said.

Bayer added that the greater impact of banning the antibiotic would be on animal health, and the potential subsequent distribution of sick animals for human consumption. Tolefson said a good portion of the hearing is likely to focus on Bayer's claim that there is no serious outcome because other treatment options are available.

"But from the food safety perspective, having 10,000 cases of fluoroquinolone-resistant Campylobacter is 10,000 too many," she said.

Tolefson said the FDA is now also conducting a risk assessment to determine whether a similar ban should be applied on the use of virginiamycin, a Pfizer Inc. antibiotic used in swine and chicken feed. Tolefson said results of that risk assessment are expected this summer.

Virginiamycin is in the same class as Aventis Pharmaceuticals' Synercid, an antibiotic used to treat life- threatening infections in hospitals.

The FDA said a pre-hearing in the Bayer case would be held on April 8 at its headquarters to schedule the official hearing. The agency said its Administrative Law Judge Daniel J. Davidson would preside both over the pre-hearing and the hearing.

Unlike the US, the use of antibiotics is banned in Europe for growth promotion but the use of fluoroquinolones is still considered acceptable. Adding antibiotics to animal feed can cause them to grow larger more rapidly, cutting the time it takes to produce food.

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