Peramivir (trade name Rapivab) is an antiviral drug developed by BioCryst Pharmaceuticals for the treatment of influenza. Peramivir is a neuraminidase inhibitor, acting as a transition-state analogue inhibitor of influenza neuraminidase and thereby preventing new viruses from emerging from infected cells. It is approved for intravenous administration. In October 2009, the U.S. Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for the use of peramivir based on safety data from Phase 1, Phase 2, and limited Phase 3 trial data. The emergency use authorization for peramivir expired in June 2010. On 19 December 2014, the FDA approved peramivir to treat influenza infection in adults. Peramivir has also been approved in Japan and South Korea and is available in Japan as Rapiacta and in South Korea as Peramiflu. As of 2015, it is the only intravenous option for treating swine flu.