Shares of BioCryst ( BCRX) gained more than 40% Friday after the company said its intravenous flu drug saw "positive results" in phase-three studies.

In a test conducted during the 2008-2009 flu season, BioCryst and co-sponsor Shionogi, a Japanese pharmaceuticals firm, compared 300 milligram and 600 milligram doses of the drug, called peramivir, with small doses of Tamiflu. The median so-called "time to alleviation of symptoms" was three hours less for the 300 milligram version (and almost an hour less for the 600) compared with Tamiflu, or 78, 81 and 81.8 hours, respectively.

Though that sounds like modest success, investors have been eager to get into BioCryst stock - and shares of other pharma firms with possible influenza drugs, for that matter -- ever since the swine flu first broke out this past spring.

Indeed, the company is seeking government approval of intravenous permavir for pre-emergency use authorization, which is bureaucratese for shipping its flu drug to the Center for Disease Control for use in an outbreak or epidemic.

The positive report also comes only a few months after BioCryst, in early May, said an oral version of peramivir failed in a clinical trial, prompting a sell-off in the stock.

BioCryst shares closed Friday at $5.93, up 41%, or $1.71, on volume of 8.3 million shares. Average daily volume is 1.8 million.

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