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Baloxavir Marboxil

Generic name: baloxavir marboxil systemic

Brand names: Xofluza

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet Therapy Pack, Oral:

Xofluza: 2 x 20 MG (2 ea); 2 x 40 MG (2 ea)


Mechanism of Action

Baloxavir marboxil is an oral prodrug that is converted to baloxavir, an inhibitor of the endonuclease activity of a selective polymerase acidic (PA) protein, which is required for viral gene transcription, resulting in inhibition of influenza virus replication. Baloxavir has demonstrated antiviral activity against influenza A and B viruses, including strains resistant to standard current antiviral agents (Hayden 2018).



Vd: 1,180 L


Baloxavir marboxil is a prodrug; completely converted via UGT1A3 (major) and CYP3A4 (minor) to the active metabolite (baloxavir)


Feces (80.1%); Urine (14.7%; 3.3% as baloxavir)

Time to Peak

4 hours

Half-Life Elimination

79.1 hour

Protein Binding

~93% to 94%

Use in Specific Populations

Special Populations Note

Body weight: As weight increases, exposure to baloxavir decreases.

Use: Labeled Indications

Influenza, seasonal, treatment: Treatment of acute uncomplicated influenza (A or B) infection in patients ≥12 years of age who have been symptomatic for no more than 48 hours and who are otherwise healthy or at high risk of developing influenza-related complications.

Limitations of use: Influenza viruses change over time, and factors such as the virus type or subtype, emergence of resistance, or changes in viral virulence may diminish the clinical benefit of antiviral drugs. Consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use baloxavir marboxil.


Hypersensitivity (eg, anaphylaxis, angioedema, urticaria, erythema multiforme) to baloxavir marboxil or any component of the formulation.

Dosage and Administration

Dosing: Adult

Influenza, seasonal, treatment: Oral:

40 to <80 kg: 40 mg as a single dose within 48 hours of onset of influenza symptoms.

≥80 kg: 80 mg as a single dose within 48 hours of onset of influenza symptoms.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Influenza, treatment: Note: Treatment should ideally begin within 48 hours of symptom onset.

Children ≥12 years and Adolescents: Oral:

40 to <80 kg: 40 mg once as a single dose.

≥80 kg: 80 mg once as a single dose.


Oral: Initiate within 48 hours of influenza symptom onset. Administer a single dose with or without food. Avoid administration with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (eg, calcium, iron, magnesium, selenium, zinc).


Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F). Store in original blister package.

Drug Interactions

Influenza Virus Vaccine (Live/Attenuated): Antiviral Agents (Influenza A and B) may diminish the therapeutic effect of Influenza Virus Vaccine (Live/Attenuated). Management: Avoid anti-influenza antivirals during the period beginning 48 hours prior to and ending 2 weeks after live influenza virus vaccine administration. Consider therapy modification

Polyvalent Cation Containing Products: May decrease the serum concentration of Baloxavir Marboxil. Avoid combination

Adverse Reactions

1% to 10%: Gastrointestinal: Diarrhea (2% [Hayden 2018])

Postmarketing: Abnormal behavior, anaphylactic shock, anaphylaxis, angioedema, bloody diarrhea, colitis, delirium, erythema multiforme, eyelid edema, facial swelling, hallucination, hypersensitivity reaction, melena, nonimmune anaphylaxis, skin rash, swollen tongue, urticaria, voice disorder, vomiting


Concerns related to adverse effects:

  • Bacterial infection: There is no evidence of efficacy of baloxavir marboxil in illnesses (eg, bacterial infections) caused by pathogens other than influenza viruses. Serious bacterial infections may begin with influenza-like symptoms, may coexist with, or occur as an influenza complication. Baloxavir marboxil has not been shown to prevent such complications. Monitor for potential secondary bacterial infections and manage appropriately.
  • Hypersensitivity: Hypersensitivity reactions, including anaphylaxis, angioedema, urticaria, and erythema multiforme have been reported; evaluate and treat accordingly.

Concurrent drug therapy issues:

  • Drug-drug/drug-food interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Monitoring Parameters

Monitor for potential secondary bacterial infections.


Pregnancy Considerations

Adverse events were not observed in animal reproduction studies.

Untreated influenza infection is associated with an increased risk of adverse events to the fetus and an increased risk of complications or death to the mother. Other agents are currently recommended for the treatment of influenza in pregnant females and females up to 2 weeks postpartum (ACOG 2018; CDC [Fiore] 2011).

Patient Education

What is this drug used for?

  • It is used to treat the flu.

Frequently reported side effects of this drug

  • Diarrhea
  • Common cold symptoms
  • Nose irritation
  • Throat irritation
  • Headache
  • Nausea

Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:

  • Dizziness
  • Passing out
  • A significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Source: Wolters Kluwer Health. Last updated January 27, 2020.