Bayer has suffered a blow with the news that patent protection in Europe on its big-selling Yasmin range of oral contraceptives has been overturned.

The board of appeal at the European Patent Office has revoked the German group's formulation patent for the Yaz/Yasmin/Yasminelle (drospirenone and ethinyl estradiol) contraceptive franchise. This follows an appeal by Novartis generics unit Hexal against a 2006 decision that had confirmed the patent which would have run to 2020 in Europe.

Bayer says that "a decision on possible next steps will be taken by the company after studying the reasons of the decision". Flemming Ornskov, head of strategic marketing general medicine, stated that "we are disappointed by the decision that the EPO didn’t concur with our legal opinion”.

However, in spite of the decision, he added that "we remain confident that we can maintain our European leadership position in women’s healthcare with innovative product launches". Bayer's late-stage pipeline includes a new hormonal intrauterine contraceptive and a contraceptive patch.

Analysts expect generic competition in Europe in the second half of 2011, but feel the fact that the pills already face patent protection in the USA, where the products are priced higher, is more of a concern to Bayer. First-quarter sales of the franchise slumped 18.3% to 242 million euros, hurt by generic competition to Yaz in the USA.