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The U.S. Food and Drug Administration (FDA) approved baloxavir marboxil, an oral tablet to be marketed as Xofluza, for treatment of early acute uncomplicated influenza in adolescents and adults.
FDA Commissioner Scott Gottlieb said in a news release,
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."
Xofluza differs from oseltamivir (marketed as Tamiflu, also available generic) in its mechanism of action. Oseltamivir inhibits the action of the viral enzyme neuraminidase (which lets viruses bud and spread from the infected cell). Baloxavir, by contrast, inhibits viral polymerase acidic endonuclease, an enzyme essential for viral replication.
In two randomized trials enrolling more than 1,800 patients, one oral dose of baloxavir significantly reduced the duration of flu symptoms, as well as infectivity / contagiousness (i.e., duration of viral shedding), and viral levels in the upper airway. This was compared to either placebo or oseltamivir.
In patients with influenza type B, Xofluza was found to be particularly more effective than oseltamivir, reducing the time to improvement of symptoms (median 75 hours compared to 102 hours).
Like oseltamivir, Xofluza is to be given in the first 48 hours of flu symptoms.
Diarrhea and bronchitis were the most common adverse reactions to Xofluza, with many other less common adverse reactions.
Xofluza will wholesale for $150 for the single dose, compared to $100 wholesale for a course of generic oseltamivir, Forbes reported. Generic oseltamivir can be found advertised for as low as $50 online, according to GoodRx. Baloxavir marboxil's single dosing, rather than 5 days of twice-daily dosing will provide a significant advantage over oseltamivir, as would its higher observed efficacy.