Drug reference

baloxavir marboxil

Cap-dependent endonuclease inhibitor (prodrug) · Antiviral (Anti-influenza)

Cap-dependent endonuclease inhibitor (prodrug)Antiviral (Anti-influenza)ATC J05AX25

CDSCO approvedATC J05AX25

EXCRETION

—

not curated

INTERACTIONS

—

none in our sources

PREGNANCY

—

not curated

Mechanism

Baloxavir marboxil is an orally administered prodrug that undergoes near complete hydrolysis to form active baloxavir acid. Baloxavir acid is a selective inhibitor of influenza cap-dependent endonuclease, blocking influenza proliferation by inhibiting the initiation of mRNA synthesis.

Indications

treatment of acute uncomplicated influenza in patients 12 years of age and older who have been symptomatic for up to 2 daystreatment of acute uncomplicated influenza in patients at high risk of developing influenza-related complicationspostexposure prophylaxis of influenza in patients 12 years of age or older following contact with an individual who has influenzatreatment of acute uncomplicated flu within 2 days of illness onset in otherwise healthy people 12 years and older or those at high risk of developing flu-related complicationspostexposure prevention of influenza for people ≥12 years old after contact with an infected personProphylaxis or treatment of uncomplicated influenza within 2 days of onset of illnessActivity against influenza A and B

Dosing

Adult: 40 mg (for individuals weighing 40 to less than 80 kg); 80 mg (for individuals weighing 80 kg or more)
Pediatric: 40 mg (for individuals weighing 40 to less than 80 kg) (12 years of age and older); 80 mg (for individuals weighing 80 kg or more) (12 years of age and older)

Pharmacokinetics

Half-life

~80 h (terminal t1/2); tmax occurs around 4 h

Bioavailability

Decreased by food (Cmax by 48%, AUC by 36%)

Metabolism

Rapidly and completely metabolized to baloxavir acid by hydrolysis (mainly by arylacetamide deacetylase (AADAC)); baloxavir acid primarily metabolized by UGT1A3 with minor contribution from CYP3A4

Excretion

Primarily eliminated by biliary excretion

Contraindications

coadministration with dairy products
coadministration with calcium-fortified beverages
coadministration with polyvalent cation-containing laxatives
coadministration with antacids
coadministration with oral supplements containing calcium
coadministration with oral supplements containing iron
coadministration with oral supplements containing magnesium
coadministration with oral supplements containing selenium
coadministration with oral supplements containing zinc
Pregnant women (CDC does not recommend due to lack of information)
Breastfeeding mothers (CDC does not recommend due to lack of information)
Outpatients with complicated or progressive illness (CDC does not recommend due to lack of information)
Severely immunosuppressed people (CDC does not recommend due to lack of information)
Hospitalized patients (CDC does not recommend due to lack of information)

Side effects

Common

diarrhea

Drug interactions

Dairy Products

Moderate

Textbook

Decreased plasma exposure and curtailed efficacy of baloxavir.

Avoid coadministration with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (e.g., calcium, iron, magnesium, selenium, zinc).

Source: G&G 14e

11 additional low-confidence interactions hidden — those rows lack a documented mechanism or management plan in our sources.

Related guidelines

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ICMR · Oncology · 2021

Infective endocarditis prevention

NICE · Cardiology / Dentistry · 2008

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AHA · Cardiology / Dentistry · 2007

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MOHFW · Endocrinology · 2021

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AHA · Neurology · 2021

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Sources: Goodman & Gilman 14e, Harrison 22e·Verified: 2026-05-10 · House clinical team