AstraZeneca's Prilosec patent ruled as invalid

The US Federal Circuit Court has upheld a 2004 ruling by the District Court, which found that Anglo-Swedish drugmaker AstraZeneca's US patent number 6,013,281, which covers the manufacture of the antiulcerant Prilosec (omeprazole), was invalid as it infringed on a pre-existing patent held by Korea's Chong Kun Dan Corp, according to a report on the SeekingAlpha news service.

The case followed efforts by several generic drugmakers, including USA-based firms Andrx and Kudco, and India's Genpharma, to produce generic versions of the drug. At the time, the Federal Circuit Court found that Andrx' generic Prilosec infringed upon two of AstraZeneca's formulation patents, numbers 4,786,505 and 4,853,230.

In the most recent ruling, which was carried two votes to one, the Court found that a Korean patent held by CKD "inherently anticipated" claim one of AstraZeneca's patent which details a formulation method by "forming in situ a separating layer" between an active ingredient core and an enteric coating. AstraZeneca has not yet issued a response.