* FDA confirms 5-year exclusivity for hyperactivity drug
* Shire shares rise 2.4 percent
(Adds detail on Actavis, sales forecast, shares, analysts)
LONDON, Oct 26 (Reuters) - Shire Plc's (SHP.L) attention-deficit hyperactivity drug business received a boost on Monday as the U.S. Food and Drug Administration confirmed its new medicine was entitled to five years of exclusivity.
Following an administrative review, the FDA found that the previously awarded exclusivity period running to Feb. 23, 2012, had been properly granted, the company said in a statement.
Shares in Shire rose 2.4 percent by 1105 GMT on the news, which prevents the FDA from accepting generic filings for Vyvanse and effectively sees off an early threat from Icelandic generics company Actavis.
Actavis had sued the FDA to overturn the exclusivity because Vyvanse is a metabolically converted drug and its active ingredient, dextroamphetamine, is the same as the older drug Adderall.
Vyvanse is an important driver for future sales at Shire, and the drug is expected to have a 13 percent share of the hyperactivity market by the end of 2009, according to analysts at Citigroup.
Thomson Pharma consensus forecasts point to Vyvanse sales of $504 million this year, rising to $1.06 billion in 2013.
GlaxoSmithKline (GSK.L) has a deal to co-promote Vyvanse for adults in the United States that was initiated in May, doubling the sales force behind the product to around 1,300 representatives. (Reporting by Ben Hirschler; Editing by Will Waterman)