AstraZeneca is celebrating a major legal victory over Teva Pharmaceutical Industries in the patent battle the firms have been waging in the USA over the Anglo-Swedish drugmaker’s blockbuster schizophrenia drug Seroquel.

The US District Court for New Jersey has granted summary judgment in AstraZeneca's favour in the case the latter brought against Teva and Novartis’ Sandoz unit. AstraZeneca had sued the two companies after they filed Abbreviated New Drug Applications seeking approval to market generic versions of Seroquel (quetiapine fumarate) in the US before its patent expires in 2011.

As a result of the New Jersey court’s decision, and given the fact that Teva and Sandoz had already conceded infringement and the validity of AstraZeneca's Seroquel patents, a trial (which had been set for August 11) is now unnecessary.

AstraZeneca chief executive David Brennan applauded the court’s decision to “uphold our valid intellectual property”, and noted that Seroquel “remains an important part of our company's portfolio”. First-quarter sales increased 10% to $1.05 billion and it is the firm’s second-best-selling product.

Last month AstraZeneca received a fresh approval from the US Food and Drug Administration to market Seroquel for the maintenance treatment of patients with bipolar I disorder, as an adjunct to lithium or divalproex. It is looking to extend the franchise through extended-release versions of the antipsychotic, called Seroquel XR and is hoping the latter will be approved by the FDA as a treatment for depression and for both manic and depressive episodes associated with bipolar disorder.

This may not be the end of the story, however, as Teva says it plans to appeal the court’s ruling. Nevertheless, investors feel the New Jersey ruling is important and by 9.20 this morning, AstraZeneca shares had already climbed 6.1% to £22.60.