The demand for Cipro has shot up all over the world
Canada announced on Thursday that it was ordering almost a million doses of a cheaper alternative in response to the massive worldwide demand for the drug.
Eight anthrax cases have now been confirmed in the United States, but thousands more people are taking Cipro as a precaution.
But the German company Bayer, which has a monopoly on Cipro, says it can easily meet the demand for the drug in Canada, and is concerned about the implications of ordering a cheap alternative.
Canadian competitor
The Canadian Government has ordered anti-anthrax pills from Apotex Inc, Canada's largest pharmaceutical company.
"It sets a dangerous precedent to have a government bypass legislative framework and request Apotex, who to date has been prevented by court order from producing ciprofloxacin, to fill an order for 900,000 tablets," Bayer's legal counsel, Neil Belmore, told Reuters news agency.
Bayer already plans to triple production of Cipro - also known as Ciproxin outside the US and Canada - to meet the increased demand.
But Apotex promises to provide ciprofloxacin - the generic name for Cipro - at 63 Canadian cents cheaper per tablet than the C$2 that each of Bayer's pills cost.
"It's not a matter of dollar and cents but the matter of availability in case of an outbreak of anthrax - do we let people die because of a patent?" Apotex chief executive Jack Kay said.
He said that if Apotex was found to be infringing on Bayer's patent then it would reimburse the German company on this order.
US considers alternatives
The US Government is also considering relaxing its patent laws to allow it to buy in cheaper alternatives to Cipro.
And drug companies are already lining up to provide this service.
Deepak Chatterraj, the head of the US arm of India's Ranbaxy Laboratories, told the BBC's World Business Report that he was ready to start shipping in December at an "attractive" but unspecified price.
Mr Chatterraj said that he and other firms had been approached by a US Senator, Jack Schumer, to ask about their readiness to supply anti-anthrax drugs if necessary.
But he denied that he had been approached directly by the US Government.
The shares of many biotechnology companies have risen sharply over the past week in response to the growing fear of bioterrorism in the United States.