GSK shares hit as Advair generics edge closer in U.S.

LONDON (Reuters) – The threat of generic copies of GlaxoSmithKline's best-selling lung drug Advair finally making it to market in the United States hit confidence in the drug maker on Tuesday, sending the stock down more than 3 percent. Fears of cheaper versions of the $8 billion-a-year seller being launched in the world's biggest market were fuelled by a draft guidance document from the Food and Drug Administration setting out the requirements for generic versions of the inhaled drug. …