UPDATE 2-BioCryst's influenza drug shows promise in study

* Study shows intravenous peramivir not inferior to Tamiflu

* Study was sponsored by its Japanese partner

* Shares up as much as 50 pct

(Adds details, stock movement)

July 17 (Reuters) - BioCryst Pharmaceuticals (BCRX.O) said a late-stage study testing the intravenous form of its experimental influenza drug peramivir showed the drug was not inferior to another flu drug, Tamiflu, sending its shares up 50 percent in premarket trade.

The study, sponsored by BioCryst's partner Shionogi & Co Ltd (4507.T) of Japan, compared the efficacy and safety of a single dose of peramivir -- either 300 mg or 600 mg -- with oral 75 mg of Tamiflu.

Both the 300 mg and 600 mg single dose peramivir groups demonstrated non-inferiority to Tamiflu.

A total of 1,099 patients were enrolled at 146 centers, the company said.

BioCryst said it is currently finalizing its plans for late-stage studies of peramivir intended to support U.S. regulatory approval, and also continuing to support the pre-emergency use authorization review of peramivir by the regulators.

In May, BioCryst said government agencies were considering the future option of providing intravenous peramivir through an emergency use authorization in the event of a severe influenza outbreak with significant hospitalizations. [ID:nBNG251032]

Shares of the company were up 50 percent at $6.30 in premarket trade. They closed at $4.22 Thursday on Nasdaq. (Reporting by Shailesh Kuber and Esha Dey in Bangalore; Editing by Aradhana Aravindan)