FDA OKs Xofluza, First New Flu Antiviral in Nearly 20 Years

Megan Brooks

October 24, 2018

The US Food and Drug Administration (FDA) has approved baloxavir marboxil tablets (Xofluza, Shionogi) for the treatment of acute uncomplicated influenza in people age 12 years and older who have been symptomatic for no more than 48 hours.

"This is the first new antiviral flu treatment with a novel mechanism of action approved by the FDA in nearly 20 years. With thousands of people getting the flu every year, and many people becoming seriously ill, having safe and effective treatment alternatives is critical. This novel drug provides an important, additional treatment option," FDA Commissioner Scott Gottlieb, MD, said in a news release.

Unlike neuraminidase inhibitors, such as oseltamivir (Tamiflu, Genentech), which inhibit the action of neuraminidase (an enzyme that frees viruses from the infected cells' surface), baloxavir marboxil prevents replication by inhibiting cap-dependent endonuclease activity of the viral polymerase.

As previously reported by Medscape Medical News, a single oral dose of baloxavir marboxil significantly reduced the duration of flu symptoms, duration of fever, length of time of viral shedding, and levels of virus in the nose and throat compared with placebo or oseltamivir among otherwise healthy people with the flu in two randomized controlled trials involving over 1800 patients. The most common adverse reactions in patients taking Xofluza included diarrhea and bronchitis.

The findings were published last month in the New England Journal of Medicine.

Xofluza was granted priority review by the FDA. Japan's health ministry approved baloxavir marboxil earlier this year. 

Gottlieb noted that although there are several FDA-approved antiviral drugs to treat flu, "they're not a substitute for yearly vaccination," which is the primary means of preventing and controlling flu outbreaks.

Seasonal flu activity often begins as early as October and November and can continue to occur as late as May. Flu activity most commonly peaks in the United States between December and February. The US Centers for Disease Control and Prevention recommends that everyone 6 months and older get vaccinated before the end of October.

Several patients including one child have already died from influenza this flu season, as reported by Medscape Medical News. A child in Florida became the first pediatric influenza fatality this season, according to the Florida Department of Health.  

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