How to Use Anti-influenza Drugs: Baloxavir Marboxil

Baloxavir marboxil (hereafter referred to as baloxavir), the prodrug of baloxavir acid, is a novel inhibitor of the cap-dependent endonuclease in the polymerase PA subunit of the influenza virus. Taken orally as a single dose, baloxavir was first approved in Japan for the treatment of influenza in 2018. Baloxavir has activity against influenza A and B viruses including neuraminidase inhibitors (NAIs) resistant viruses. Baloxavir showed efficacy in alleviating influenza symptoms compared to placebo both in otherwise healthy adolescents and adults, and in those at higher risk of influenza complications in randomized, double-blind, placebo- and oseltamivir-controlled phase III trials without evident safety concerns. The baloxavir effectiveness in otherwise healthy pediatric patients was also shown in a single arm, non-controlled phase III trial, compared with outcomes of previous placebo-controlled pediatric studies for NAIs. Furthermore, baloxavir showed efficacy in ameliorating influenza symptoms against influenza B, more rapid reduction in influenza viral load, less frequent influenza-related complications compared to placebo or oseltamivir. The emergence of reduced susceptibility viruses to baloxavir following exposure to the drug warrants further investigation. However, currently available evidence suggests that baloxavir, with the benefits of a single dose oral regimen, provides a new and convenient therapeutic option for the treatment of influenza patients.