Bayer and GlaxoSmithKline are eyeing a $1 billion-plus (€899 million) sales opportunity after winning US approval for anti-impotence pill Levitra, the first rival to Viagra in the world's top market.
The green light from the Food and Drug Administration, received late on Tuesday, was vital for Bayer whose sub-scale pharmaceuticals business is trying to recover from the disastrous withdrawal of cholesterol drug Baycol two years ago.
Pfizer, which succeeded in turning Viagra into a household name, said it was not concerned about the challenge from Levitra.
"Viagra remains the gold standard," said Mr Daniel Watts, a Pfizer spokesman. "It's a name that's trusted, and we're very confident that Viagra will retain its pre-eminent status."
Shares of the German chemicals conglomerate were among leading blue-chip gainers in Europe yesterday, rising 2.4 per cent to €19.90. GlaxoSmithKline shares, however, were little changed.
Analysts said Levitra's approval had been widely expected and the fact it had been developed by Bayer researchers did little to underpin confidence in GSK's science.
GSK has acknowledged its pipeline of experimental drugs in late-stage development is thin but hopes to prove it still has what it takes to find blockbusters when it hosts a keenly awaited R&D day in December.
Levitra is expected to be available in the United States in September, ahead of another challenger to Pfizer's Viagra, called Cialis, from Lilly-Icos.
Lehman Brothers estimates the new pill will achieve peak annual sales of $1.2 billion. GSK and Bayer hope to lure the millions of men suffering erectile dysfunction who have not sought treatment. All three drugs are already competing in Europe.
