FDA Expands Approval of Influenza Treatment to Post-Exposure Prevention

The U.S. Food and Drug Administration (FDA) expanded the approved indication for Xofluza (baloxavir marboxil) to include post-exposure prevention of influenza (flu) for patients 12 years of age and older after contact with an individual who has the flu. Xofluza, previously available only in tablet form, is also now available as granules for mixing in water. Xofluza was originally approved in 2018 for treating uncomplicated flu in patients 12 years of age and older who have been symptomatic for no more than 48 hours.

"This expanded indication for Xofluza will provide an important option to help prevent influenza just in time for a flu season that is anticipated to be unlike any other because it will coincide with the coronavirus pandemic," said Debra Birnkrant, M.D., director of the Division of Antiviral Products in the FDA's Center for Drug Evaluation and Research. "Americans will have to be more vigilant than ever as these viruses spread concurrently."

Flu is a contagious respiratory illness caused by influenza viruses. Treating flu patients with antiviral drugs within 48 hours of their becoming sick can reduce symptoms and duration of the illness. An annual seasonal flu vaccine is the best way to protect against the flu.

Xofluza's safety and efficacy for post-flu exposure prevention is supported by one randomized, double-blind, controlled trial in which 607 subjects, 12 years of age and older who were exposed to a person with influenza in their household, received either a single dose of Xofluza or a single dose of a placebo. Of these 607 subjects, 303 received Xofluza and 304 received the placebo. The trial's primary endpoint was the proportion of subjects who were infected with influenza virus and presented with fever and at least one respiratory symptom from day 1 to day 10. Of those who received Xofluza, 1% of subjects met these criteria, compared to 13% of subjects who received a placebo for the clinical trial.

The most common side effects of Xofluza include diarrhea, bronchitis, nausea, sinusitis and headache.

Hypersensitivity, including anaphylaxis (allergic reaction), can occur in patients taking Xofluza. Patients should not take Xofluza if they have had a known hypersensitivity reaction to Xofluza. Xofluza should not be co-administered with dairy products, calcium-fortified beverages, or laxatives, antacids, or oral supplements containing calcium, iron, magnesium, selenium, aluminum or zinc.

The FDA granted the approval of Xofluza to Genentech USA.