Bayer AG said it will "resolutely" fight several legal claims that have emerged in the US against the validity of its patent on anti-anthrax drug Cipro.
In a statement, Bayer said that its patent on Cipro "is not in question" until it runs out in 2003.
The company admitted that back in 1998 it made an out-of-court settlement with the US firm Barr Laboratories, which brought an infringement case against Bayer's patent on Cipro.
Bayer said it had made the settlement due to the uncertainty of such a case, as well as related costs, even though it was convinced of its patent's validity.
Competitors who are now bringing forward legal complaints against Bayer's Cipro patent in the US in the midst of the current anthrax scare are now citing the settlement with Barr, Bayer said.
"Bayer will defend itself resolutely against these procedures," it said.
It said even after the Barr settlement, the US authorities had confirmed the validity of the Cipro patent and did so once more at the beginning of this year.
Cipro, the trade name for ciprofloxacin, has been approved in the US to treat respiratory anthrax, the most lethal form of the disease.
A grouping of US consumer associations yesterday filed suits against Bayer saying it illegally conspired with other pharmaceutical companies to keep cheaper generic versions Cipro off the US market.