What is the recommended dose of Xofluza (baloxavir marboxil) for a patient 12 years or older with impaired renal function or other underlying medical conditions?

Xofluza (Baloxavir Marboxil) Dosing

For patients 12 years or older, Xofluza is dosed as a single oral dose based on body weight: 40 mg for patients weighing 40-80 kg, and 80 mg for patients weighing ≥80 kg, regardless of renal function or underlying medical conditions. 1

Standard Dosing Regimen

Weight-based single dose administration:

• 40-80 kg: 40 mg orally as a single dose 1
• ≥80 kg: 80 mg orally as a single dose 1

The medication must be administered within 48 hours of symptom onset for maximum effectiveness 2, 3, 4

Renal Impairment Considerations

No dose adjustment is required for patients with impaired renal function. 1 This represents a significant advantage over oseltamivir, which requires dose reduction when creatinine clearance falls below 30 mL/min 1, 5. The lack of renal dose adjustment makes baloxavir particularly practical for elderly patients and those with chronic kidney disease 1.

Patients with Underlying Medical Conditions

The same weight-based dosing applies to high-risk patients with underlying medical conditions including:

• Age >65 years 6
• Chronic pulmonary disease 1
• Cardiovascular disease 1
• Diabetes 1
• Immunodeficiency 1

The CAPSTONE-2 trial specifically demonstrated efficacy in high-risk outpatients, with median time to symptom improvement of 73.2 hours with baloxavir versus 102.3 hours with placebo (difference 29.1 hours, p<0.0001) 6.

Administration Guidelines

Critical administration considerations:

• Do NOT administer with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements (calcium, iron, magnesium, selenium, zinc) 1
• Can be administered orally or via feeding tube 1
• Single dose eliminates adherence concerns compared to 5-day oseltamivir regimens 2, 3

Special Populations

Pregnancy and breastfeeding: Baloxavir is not recommended for pregnant or breastfeeding women 1

Severely immunocompromised patients: Baloxavir is not recommended as monotherapy due to concerns about resistance emergence 1. In the phase 3 trial, polymerase acidic protein variants with reduced susceptibility emerged in 9.7% of baloxavir recipients 4.

Prophylaxis Dosing

For post-exposure prophylaxis in patients ≥12 years:

• 40-80 kg: 40 mg orally as a single dose 1
• ≥80 kg: 80 mg orally as a single dose 1

Common Pitfalls to Avoid

• Do not delay treatment beyond 48 hours of symptom onset, as efficacy decreases significantly 2, 3
• Do not co-administer with polyvalent cations (dairy, supplements, antacids), which can reduce absorption 1
• Do not use as monotherapy in severely immunocompromised patients due to resistance concerns 1
• Do not assume renal dose adjustment is needed—unlike oseltamivir, baloxavir requires no modification for renal impairment 1

Clinical Efficacy

Baloxavir demonstrates superior viral load reduction compared to oseltamivir at 1 day post-treatment, though time to symptom alleviation is similar between the two agents 6, 4. The single-dose regimen offers practical advantages for adherence while maintaining comparable clinical efficacy to the 5-day oseltamivir course 2, 3.