FDA Backs Antibiotic as a Treatment for Inhaled Anthrax

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July 28, 2000 (Washington) -- Long regarded as a potential weapon for biological warfare and bioterrorism, the mere mention of anthrax usually strikes fear in the hearts of the public and military alike. But there is reason for hope: A panel of expert advisers to U.S. health officials confirmed Friday that an already widely used antibiotic may be an effective treatment for inhaled anthrax when given immediately following an attack.

Meeting at the urging of U.S. government officials, who already support the use of this antibiotic, the panel unanimously concluded that Bayer's antibiotic Cipro (ciprofloxacin) be approved as a treatment for inhaled anthrax. Should the FDA now follow its committee's recommendation, Cipro would become the first drug approved as a response to a biological attack.

Anthrax is a dangerous, infectious disease caused by the bacterium Bacillus anthracis. Most anthrax infections occur when the bacterium enters a cut from handling the hide, leather, or hair of an infected animal. But it also can be inhaled and spread by eating infected animals.

These infections usually are treatable with two other antibiotics, penicillin and vibramycin. However, the military believes that about 14 nations, including Iraq and North Korea, have developed several strains of airborne anthrax specifically resistant to these antibiotics for use as biological weapons. Left untreated, inhaled Anthrax results in death with one to two days.

Determining whether Cipro is an effective treatment for this potential threat was a problem, but given the potential need for an alternative to penicillin and vibramycin, there really was no other option than to support Cipro's approval for this use, committee members said.

The problem was that the committee had to make its decision based on the results of animal studies and Cipro's historical treatment profile. Human studies were not possible because of ethical concerns regarding the testing of deadly bacteria on people.

Cipro, first approved in 1987, is indicated for a number of different respiratory and urinary tract infections. Because the symptoms of inhaled anthrax resemble that of a common cold, it would be fair to assume that inhaled anthrax also might be susceptible to Cipro, argued Andrew Verderame, associate director of regulatory affairs at Bayer.

In animal studies, Cipro also provided an equal amount of protection to antibiotics already used to treat the natural form of anthrax, added Arthur Friedlander, MD, a U.S. army medical researcher. Extended treatment for a 30-day period resulted in about a 70 to 90% survival rate when tested on animals, he informed committee members.

Bayer already is supplying both the CDC and Department of Defense with Cipro, Lawrence Posner, MD, global head of regulatory affairs at Bayer, tells WebMD. Bayer also is capable of producing additional supplies on short notice should it prove necessary, he says.

"Yes, we do have ciprofloxacin," Steve Bice tells WebMD. Bice is the branch chief of the National Pharmaceutical Stockpile branch at the CDC. He emphasizes, however, that it is too soon to commit to any one particular drug in preparing for an anthrax attack. Stockpilers are still looking at other drugs as well. They are waiting for the FDA to make its official ruling on what will be the drugs of choice, then, Bice says the government will go to the drug manufacturers to increase supplies of drugs the FDA deems appropriate.