Israeli generic drugmaker Teva Pharmaceutical Industries has filed a patent challenge against AstraZeneca by filing for approval to market a generic version of the latter’s schizophrenia treatment Seroquel (quetiapine) in the USA.

Seroquel is AstraZeneca's second biggest-selling drug, bringing in revenues of $1.3 billion dollars in the first six months of 2005, up 37% year-on-year. Last year, the drug accounted for a tenth of AstraZeneca’s total sales, and its importance to the Anglo-Swedish firm has been reinforced by recent product disappointments, including the failure of its anticoagulant, Exanta (ximelagatran), to secure approval in the crucial US market [[13/09/04a]] and the failure of its lung cancer drug Iressa (gefitinib) to show a survival benefit in a key trial [[20/12/04b]].

AstraZeneca said it would vigorously defend its patent estate for the product, which extends out to 2012. It expects to file a patent infringement lawsuit against Teva within the next 45 days, which will have the effect of staying any FDA approval of the generic for up to 30 months, putting the launch date for Teva’s drug back to at least 2008 - unless of course a court judgement goes against AstraZeneca.

Teva’s Abbreviated New Drug Application is for 25mg quetiapine fumarate tablets, and its challenge related to US Patent No 4,879,288, which describes the active pharmaceutical ingredient in AstraZeneca’s product.