A medication used to treat the flu.


A polymerase acidic endonuclease inhibitor used to treat uncomplicated influenza.


Baloxavir marboxil is an antiviral drug developed by Shionogi Co., a Japanese pharmaceutical company and Roche for the treatment of influenza A and influenza B infections. The drug was initially approved for use in Japan in February 2018 and approved by the FDA on October 24, 2018 [10], [2] for the treatment of acute uncomplicated influenza in patients 12 years of age and older who have been symptomatic for no more than 48 hours [FDA label]. Baloxavir marboxil, a cap-endonuclease inhibitor, has a unique mechanism of action when compared to the currently existing neuraminidase inhibitor drug class used to treat influenza infections [1].



For the treatment of influenza A and B virus infection [4, Read more


Baloxavir marboxil is a selective inhibitor of influenza cap-dependent endonuclease which prevents polymerase function and therefore influenza virus mRNA replication [ Read more

Mechanism of action

This drug is a CAP endonuclease inhibitor [4]. The influenza endonuclease is an essential subdomain of the viral RNA polymerase enzyme. CAP endonuc... Read more


Tmax: 4h [FDA label]

Protein binding

92.9 - 93.9 % [FDA label]

Volume of distribution

1180 (V/F, L) [FDA label].


10.3 L/h [FDA label]

Half life

Terminal elimination half-life: 79.1 h [FDA label].

Route of elimination

14.7 % of a single dose is excreted in the urine, and 80.1% excreted in the feces [FDA label]


Ld50 (oral, rats): >2000 mg/kg [MSDS]

**Pregnancy Risk**

There are no available data on the use of this drug in pregnant women to predict or inform a drug-associated risk of adverse developmental outcomes. However, there are known risks to the mother and fetus associated with influenza virus i... Read more

Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Diahrrea US
  • Kind: control
    • Percent: 3
  • Bronchitis US
  • Kind: control
    • Percent: 2%
  • Nausea US
  • Kind: control
    • Percent: 1
  • Nasopharyngitis US
  • Kind: control
    • Percent: 1
  • Headache US
  • Kind: control
    • Percent: 1
  • Nausea US
  • Kind: control
    • Percent: 1
  • Contraindications

    • Route:
      • Oral
    • Hypersensitivity:
      • true
    • Regions: US

    Food Interactions

    Avoid antacids.

    Avoid multivalent ions. Multivalent ions such as magnesium, calcium, and aluminum can form a chelate with baloxavir, which can reduce the absorption of baloxavir.

    Take with or without food.