Shionogi & Co. forecast that its experimental treatment peramivir will earn annual sales of about ¥5 billion in Japan on demand from hospitals for patients critically ill with influenza, including swine flu.

Shionogi plans to file data to the health ministry in November for approval to market the flu medication and expects to sell it as early as October next year, Takuko Y. Sawada, head of development at the Osaka-based company, said in an interview.

If approved, peramivir would compete with antiviral drugs such as Roche Holding AG's Tamiflu and GlaxoSmithKline PLC's Relenza. Sawada said peramivir, which has completed all three typically required trial stages, is administered directly into the bloodstream, allowing it to take effect more rapidly.

"It's a good drug for severely ill flu patients, for whom it's critical that antivirals are effective with a high degree of certainty," Sawada said in Osaka Tuesday. There is demand for intravenously administered drugs for such patients, she said.

Relenza is usually inhaled, while Tamiflu comes in pill form. Relenza administered in an unapproved intravenous form helped save a cancer patient with swine flu whose immune system was weakened by chemotherapy, the Lancet medical journal reported this month.

Shionogi agreed in March 2007 to pay as much as $35 million to Birmingham, Ala.-based BioCryst Pharmaceuticals Inc. for rights to develop and sell peramivir in Japan.

Sales at Shionogi, also the maker of the Crestor cholesterol pill, rose 6.2 percent to ¥228 billion in the year that ended March 31. Net income fell 38 percent to ¥16 billion on costs related to an acquisition.

The company is the first among three drugmakers to seek approval in Japan for flu treatments under development. Daiichi Sankyo Co. said in July it aims to submit data for laninamivir, a longer acting form of Relenza, by next March. Fujifilm Holdings Corp.'s Toyama Chemical Co. unit plans to apply for approval for its favipiravir treatment by March 2011.

Shionogi is considering making the active ingredient in peramivir itself in the future to ensure supplies, Sawada said. For now, the company will import the ingredient from a U.S. maker to produce courses for about 3 million people next year, she said, without identifying the supplier or providing a more specific time frame.