Pfizer has failed in a bid to defend one of the patent’s covering its top-selling drug, the cholesterol-lowerer Lipitor, in Austria, but said the ruling does not clear the way for the launch of generic copies of the brand.

A panel of Austrian judges upheld an earlier decision by the Austrian Patent Office that the patent in question was invalid, but Pfizer insisted that Lipitor (atorvastatin) is still protected in Austria by other intellectual property – including a basic patent on Lipitor that does not expire until 2011 - and the ruling has no bearing on any other jurisdiction.

Indian drugmaker Ranbaxy is trying to break Pfizer’s exclusivity on Lipitor – sales of which topped $13 billion in 2005 - by challenging the validity of patents in countries around the world. It said the ruling “validates our strategy to successfully commercialize atorvastatin in Austria, and potentially other healthcare markets in the future.”

But Ranbaxy will not be able to launch generic atorvastatin in Austria unless it can break Pfizer’s basic patent in a case due to deliver a verdict later this year.

The Indian company has already suffered defeats in the courts in attempts to invalidate Pfizer’s patent position in the USA, UK, Norway, Romania and Peru. A number of these decisions are being appealed by Ranbaxy.