NEW YORK (Reuters) - Pharmacists in New York have sold greater-than-normal amounts of antibiotics for treating anthrax, a highly contagious and potentially fatal disease, amid rising fear of biological warfare after the attacks on the World Trade Centre.

Though sales of antibiotics normally rise in September when children return to school and parents are concerned about their exposure to infections, pharmacists said the sale of Bayer AG's anti-microbial drug Cipro are much higher than usual.

Cipro, the German drug maker's best-selling drug, is used to treat a number of diseases and infections, including anthrax, a disease that can cause bleeding blisters, difficulty in breathing, shock and coma. Even with early treatment, the inhalation of anthrax spores is almost always fatal.

"We're hearing that Cipro is a front-line defence against anthrax and in the last couple of days I've sold about a month's worth," said Barry Reiter, chief operating officer of Brooklyn-based Remo Drug Corp., one of the largest independent pharmaceutical supply companies in America.

"Today we'll be out of stock and we've already reordered," Reiter said Tuesday.

The U.S. Federal Aviation Administration on Tuesday said crop-duster planes could fly again after they were grounded for two days because of rising fear of biological or chemical attack in the wake of the Sept. 11 hijacked jetliner attacks in New York and outside Washington.

Bayer said it sells worldwide about $1 billion a year of Cipro, a drug used to treat urinary tract and gastrointestinal infections, as well as pneumonia and bronchitis. The drug was approved by the U.S. Food and Drug Administration to treat exposure to anthrax in August 2000 and it is the only orally administered drug recommended for such use by the Centres for Disease Control and Prevention in Atlanta.

The dosage to treat anthrax is two pills a day for 60 days, while a patient suffering from a gastro-intestinal infection would take two of the Cipro pills a day for about a week.

CIPRO DEMAND SOARS

Sylvia Lifshitz, a pharmacist at independent Drug Mart on Manhattan's Upper East Side, normally prescribes about 300 Cipro tablets in a two- to three-week period.

Over the first weekend after the World Trade Centre attacks, however, Lifshitz dispensed about 1,000 Cipro tablets in three days.

"I've never done that before," Lifshitz said, adding that most of her customers have been "highly educated and highly neurotic."

Lifshitz ordered extra Cipro, which cost about $1 a tablet, after New York physicians began prescribing it for themselves and their families, and currently has a stock of about 1,200 pills in the store, even though she is uncertain of its efficacy against anthrax.

Robert Berman, co-owner of Kings Pharmacy, which has six stores in New York City, including one near the World Trade Centre, said he has also seen a large rise in requests for Cipro.

"I had one guy come in and buy a two-month supply for him and his wife," said Berman.

Chain drug store Rite Aid Corp., which has 30 stores in Manhattan, said more antibiotics normally are sold in September, though it had not noticed an unusual rise in the sale of Cipro.

Cipro is not the only antibiotic available for treatment of inhaled microbes. Generic doxycycline, usually prescribed to prevent traveller's diarrhoea, is another anti-microbial drug that normally sees a rise in sales in September.

"People are panicking, and we've had more than the usual number of inquiries about doxycycline, too," said pharmacist Gary Halpern at the Caligor Pharmacy on Manhattan's Upper East Side, most of whose business has come from selling vaccines.

NO SUPPLY SHORTAGE

David Siegrist, a research fellow and the director of studies for the Countering Biological Terrorism program at the Potomac Institute for Policy Studies in Arlington, Virginia, said there was a reason for doctors' choosing Cipro first.

"It's believed that terrorists could make their anthrax resistant to doxycyline, but Cipro is more complicated," Siegrist said. He said that Cipro is the anti-microbial drug of choice for the U.S. military, which bought doses for the troops that served in the Gulf War in 1991.

"It wouldn't hurt to have a little Cipro on hand now," Siegrist said.

Pharmacists need not fear of a supply shortage, said Bayer, which makes the drug in a plant in Westhaven, Connecticut, and in Europe.

"We've got no supply issues at this point and people should rest assured that we have been working with the CDC and the Department of Defence for over a year," said spokesman Rob Kloppenburg.