Shares in AstraZeneca rose sharply in London Wednesday after the drug company won a U.S. court ruling to protect a patent for its blockbuster cholesterol drug, Crestor.
The U.S. District Court in Delaware ruled on Tuesday that a key patent for Crestor was valid, the company said.
AstraZeneca sold $4.5 billion worth of Crestor, its third-largest seller, in 2009.
As the London Stock Exchange opened, AstraZeneca shares were up 8.7 percent at 257 pence ($3.87).
The shares rose 9 percent to close at $48.74 Tuesday on the New York Stock Exchange.
The case began in 2007 when nine generic drug manufacturers challenged AstraZeneca's patent on rosuvastatin calcium, the active ingredient in Crestor. The patent expires in 2016.
AstraZeneca and Shionogi, the owner of the patent, then filed patent infringement suits against eight manufacturers or subsidiaries: Apotex, Aurobindo, Cobalt, Mylan, Par, Sandoz, Sun and Teva.
The ruling prevents any of the companies from securing their abbreviated new drug applications until 2016, AstraZeneca said.
"We believe that this removes a significant overhang from the AstraZeneca investment case given its recent growth," said Brian White, analyst at Shore Capital in London.
"Crestor remains AstraZeneca's main growth driver ...and we forecast the franchise should generate revenues of $7.2 billion in the fiscal year 2012, rising up to $8.6 billion in 2014," said Tom Kemp, analyst at Panmure Gordon.
Kemp said Crestor sales in the U.S. would represent 12.2 percent of the group's revenues in the fiscal year 2012, about 18 percent of profits.
Both analysts rated the shares as "buy," but Emmanuel Papadakis at Collins Stewart saw trouble ahead and listed the shares as "sell."
"The patent cliff has started," Papadakis said.
"Pfizer's Lipitor, which has a 50 percent share of the statin market, loses protection 2011.We find it hard to see how Crestor will grow significantly in a dramatically genericizing therapeutic class," he added.
Apotex, based in Toronto, announced in May that it had launched a generic version of Lipitor in Canada.
At the same time, the Israeli company Teva Pharmaceutical Industries Ltd. also won permission to sell its generic version of Lipitor in Canada.