A European patent covering technology used in Boston Scientific’s Taxus coronary stent has been invalidated in a UK court, raising the threat of competition to the product.

The court invalidated the UK designation of the patent, held by Angiotech Pharmaceuticals which covers intellectual property relating to the paclitaxel coating used on Taxus. The companies pointed out that only the UK market is affected, and Angiotech said it intends to appeal the ruling.

The patent-busting suit was brought by Canadian firm Conor MedSystems, which last week won European approval to sell its own paclitaxel-eluting stent, CoStar, in competition to Taxus.

Conor said it had already started shipping its stent, which is scheduled to be submitted for approval in the USA next year, pending the completion of pivotal studies. Other lawsuits with Angiotech are ongoing in the USA, the Netherlands and elsewhere, according to the firm.

At the moment, the market for cardiovascular drug-eluting stents is split between Boston Scientific and arch-rival Johnson & Johnson, which sells a product called Cypher (sirolimus). J&J is claiming a majority share of the world market for this type of product, although Boston Scientific insists Taxus is still ahead in the USA, with 54% of the market.

Another upcoming entrant is Guidant - due to be acquired by Boston Scientific later this year - which is planning to launch its Xience V (everolimus) drug-eluting stent in the second quarter of this year.