Johnson & Johnson’s Cordis subsidiary has said it will appeal a federal court ruling that upheld a jury verdict last year that its Cypher drug-eluting stent infringes the intellectual property of rival medical device maker Boston Scientific.

In the latest development, Judge Sue Robinson of the US District Court in Delaware denied J&J's motion to overturn the earlier judgment, which found Cypher (sirolimus) infringed Boston Scientific's so-called ‘Ding’ patent covering drug-coated stents that are used to prevent coronary arteries re-blocking after being cleared using angioplasty procedures.

Last month Robinson ruled that both Cordis and Boston Scientific were guilty of infringing each other's patents covering coated and non-coated cardiovascular stents, leaving the two firms at an impasse.

In the latest round the two companies also shared the legal spoils – with two judgments apiece in their favour – but the most significant commercially is the one relating to the drug-eluting stents. Cordis said it would appeal the latest ruling.

Boston Scientific has been desperate to slow the encroachment of Cypher into its Taxus market share. Between them, the two products dominate the $5.5 billion coated stent market, with roughly a half-share apiece, although both are facing competition for the first time from other coated stents, including Xience V from Abbott (formerly Guidant), which is due to reach the European market in the third quarter of this year.

Meanwhile, Medtronic has launched its own drug-eluting stent, Endeavour (zotarolimus), in Europe and other parts of the world and is scheduled to introduce it in the USA next year. And Canadian firm Conor MedSystems earlier this year won European approval to sell its own paclitaxel-eluting stent, CoStar, in competition to Taxus. Conor is suing Boston Scientific to try to invalidate the patent protection on Taxus' paclitaxel coating.