Shawnee ? The Bayer Corp., facing new calls for bans on its animal version of the anthrax-fighting drug Cipro, plans to take the case to an administrative law judge later this year.

Doctors turned to Cipro when terrorists sent out anthrax-laced letters that sickened 13 people and killed five last year. Bayer also makes Baytril, the animal version of Cipro, at its animal health facility in Shawnee, a suburb of Kansas City.

Baytril is used to treat respiratory problems in poultry.

The Bayer Corp., the U.S. subsidiary of the German pharmaceutical maker Bayer AG, has been battling an attempt by the Food and Drug Administration to ban the use of fluoroquinolones, which include Baytril, for poultry.

The FDA says that since 1995, when Baytril was approved for poultry, there has been a dramatic increase in the percentage of cases in which people developed food-borne illnesses that resisted treatment by Cipro and other human forms of those drugs.

FDA officials agreed with Bayer that there is no scientific foundation for saying that Baytril’s use in chickens will make Cipro less effective in treating anthrax.

“The debate as to the use of antibiotics in food-producing animals has been going on since the 1970s. Only in the past five years have we had good data that shows human health is impacted,” said Linda Tollefson, a veterinarian and deputy director of the FDA’s Center for Veterinary Medicine, which is seeking the ban.

Some congressmen and medical and consumer groups, which support banning the drug, are pressuring Bayer to pull Baytril. They point to the potential of future bioterrorism attacks in their arguments.

Sen. Harry Reid of Nevada recently sent Bayer a letter saying that if the company does not voluntarily withdraw the drug, he will introduce legislation to phase out Baytril’s use in poultry.

“Like all Americans, the recent anthrax attacks (have) made me more keenly aware of the importance of ensuring the viability of drugs like Cipro for treating anthrax and other numerous diseases,” Reid said in his letter to Bayer Chief Executive Helge Wehmeier.

“Although no evidence yet indicates that Baytril use in poultry threatens our ability to treat anthrax, FDA has concluded that such use is already making Cipro less effective in treating other disease-causing bacteria, such as those that cause severe food poisoning.”