* GSK says considering appeal to a higher court
* Ruling in favour of Novartis NOVN.VX units Sandoz, Hexal
(Adds details, background, GSK shares)
LONDON, Jan 26 (Reuters) - GlaxoSmithKline (GSK.L) lost a Dutch patent case on Wednesday on its top-selling lung drug Advair, in the latest in a series of legal battles across Europe over the inhaled medicine.
Advair, or Seretide as it is known in most of Europe, is a key product for GSK, selling 5 billion pounds ($7.9 billion) last year and accounting for 18 percent of group revenue.
GSK said in a statement a court in The Hague had ruled in favour of joint claimants, Novartis NOVN.VX units Sandoz BV and Hexal AG, in deciding that the Dutch part of the European patent for Advair, as well as the supplementary protection certificate (SPC), was not valid.
“GSK is currently studying the judgment and will be considering the possibility of an appeal to a higher court,” the British drugmaker said.
Shares in GSK dipped slightly after the news, but were trading 1.5 percent higher on the day at 1255 GMT.
GSK has already suffered patent defeats on Advair in Britain, Ireland and Germany. [ID:nLDE64J0R0] (Reporting by Kate Kelland; Editing by Paul Sandle and David Holmes) ($1=.6324 Pound)