Patent protection of the world’s biggest selling drug, Pfizer’s $12-billion a year cholesterol-buster Lipitor, has taken a hit in Norway, after a court ruled in favour of challenger Ranbaxy Laboratories in its fight to sell a copycat version.

The Oslo City Court decided that Ranbaxy’s generic version of Lipitor (atorvastatin) does not infringe on two of the branded drug’s patents, which follows a similar ruling on a third patent earlier this year.

But towards the end of 2005, the court ruled that a fourth patent was being infringed upon, thereby preventing the Indian drugmaker from launching its product until this expires in February 2009. Therefore, this latest ruling has “no practical effect” on Lipitor’s current protection in Norway, Pfizer said in a statement, adding that in other European markets, the drug is protected until 2011.

Ranbaxy is fighting hard to sell its generic version of Lipitor around the globe. Earlier this month, a US court backed the validity of the main patent protecting the drug, although it ruled a second patent invalid on technical grounds. This basically means that Ranbaxy can launch a copycat in the US in 2010 rather than 2011.

Ranbaxy is among those generic companies that adopt a high-risk, high-reward strategy in the sector, spending on litigation in the hope of winning first-to-market advantage for its generic products. But its hopes of winning an early entry into the atorvastatin market must be receding, given Pfizer’s recent victories in the UK, Finland, Spain, Norway, Romania, Peru, and the USA.