FDA expands approval of baloxavir marboxil for post-exposure influenza prevention

The US Food and Drug Administration (FDA) has expanded the indicated use of baloxavir marboxil (Xofluza) to include post-exposure influenza prevention in patients Older than 12 years after they had come in contact with someone with the flu.

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.

The FDA has granted the approval of Xofluza to Genentech USA, Inc.

Baloxavir has a unique mechanism of action, however. Whereas other flu antivirals including oseltamivir target the flu virus's neuraminidase enzyme, baloxavir inhibits its cap-dependent endonuclease.

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.

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."