Swedish authorities have approved a copycat version of GlaxoSmithKline's top-selling lung drug Advair in a move that also clears the way for its launch in several other European markets, including Germany and Italy.

The green light for the product from Greek firm Elpen given by Sweden's Medical Products Agency underscores the looming challenges to GSK's blockbuster inhaled medicine, which had worldwide sales of 5.14 billion pounds ($8.44 billion) in 2010.

Other generic drugmakers, including Novartis unit Sandoz, are also working to win approval for copies of GSK's medicine in Europe.

The Swedish agency issued its decision on Elpen's drug last month, but the decision was not publicised by the companies involved. Elpen's regulatory filing was handled by consultancy firm Pharos.

Sofia Grypaiou, a regulatory affairs official at Pharos, told Reuters that Elpen was now evaluating its launch plans. She declined to comment on how much the drug would cost or whether Elpen would bring in a partner to sell it outside Greece.

Because Sweden was acting as the reference state under Europe's decentralised approval procedure, the move also means the drug has the go-ahead in Germany, Italy, Portugal, Hungary, and the Czech and Slovak republics, subject to final clearance from local authorities.

Elpen's medicine contains the same two active ingredients as Advair -- also known as Seretide and as Viani in Germany -- but it comes in a very different inhaler device, requiring patients to load a double blister strip before use. The strip contains the drugs fluticasone and salmeterol.

The product has been available under the brand name Rolenium since November 2009 in Greece, where it has a market share of 9 percent against 43 percent for GSK's drug, and 36 percent for AstraZeneca's rival and different medicine Symbicort, according to figures from Elpen.

GSK said it did not believe Elpen's drug would be easily switched for its own popular product.

"GSK's Seretide is available in a dry powder inhaler formulation in the Accuhaler/Diskus device which has unique characteristics and patient handling properties, and is substantially different from the Elpen device," a spokesman for GSK said.

"GSK therefore believes the products would not be substitutable," he added.  - Reuters