India’s Ranbaxy Laboratories was jubilant yesterday after the Austrian Patent Office invalidated a patent covering Pfizer’s biggest selling drug, the $11 billion dollar-a-year cholesterol-lowerer, Lipitor (atorvastatin).

The Austrian panel of five judges agreed that the specific patent claims were invalid and that the patent in question lacked an inventive step. The ruling only applies to the Austrian market, where the product is sold under the brand name, Sortis, but Ranbaxy has challenged the patent in other markets around the world, including the all-important USA.

Pfizer said that it would appeal the decision, and says it is confident that it will be able to make a “compelling argument” in support of its patent. It said that the appeals process would take about a year. In addition, the firm noted that Lipitor is protected by a separate “composition-of-matter” patent in Europe, which is not set top expire until 2011. Ranbaxy has also challenged this patent in Austria, but no hearing has been scheduled.

- Meanwhile, there was a piece of good news for the world’s largest pharmaceutical company after it obtained a preliminary injunction against Teva and Ranbaxy, which halts sales of a generic version of the former’s high blood pressure medicine, Accupril (quinapril).

Teva launched its version of the drug back in December last year under its own label as part of an agreement with Ranbaxy. However, a US district court held that Pfizer was likely to prevail in an ongoing patent infringement lawsuit filed in January this year, and ordered the injunction to prevent further sales of the Teva-marketed product while Pfizer seeks a permanent injunction.

Pfizer says it will be seeking damages resulting from lost sales, while Ranbaxy said that although it would comply with the ruling it would be appealing, saying it was “confident that it will, on appeal, be able to make a compelling argument in support of its non-infringement position.”