AstraZeneca loses UK patent appeal on Losec

The UK Court of Appeal has dismissed an appeal by AstraZeneca on two patents relating to its block-buster drug, Losec (US: Prilosec), the world's second-biggest selling medicine. In March, the High Court ruled that two formulation patents on the ulcer treatment were invalid.

The patent on the active substance in Losec, omeprazole, expired in the UK in April this year. AstraZeneca had also obtained patents covering the formulation, a so-called 'separating layer,' which would have extended its monopoly on the product for a further five years. However, the High Court found against AstraZeneca and ruled that the claimed invention was obvious.

This decision contrasts with a recent US District Court decision, in which corresponding US patents on AstraZeneca's formulation were found to be valid. A final judgment in this case is expected within the next few days.

Generic pharmaceutical manufacturers, including Merck KGaA affiliate Generics UK, had launched their own versions of omeprazole earlier in the year, following the High Court judgment. The Appeal Court ruling means that generic omeprazole will continue to be available to patients in the UK.