Xofluza Dosing for Influenza
Xofluza (baloxavir marboxil) is administered as a single weight-based oral dose: 40 mg for patients weighing 20 to <80 kg, and 80 mg for patients weighing ≥80 kg, taken within 48 hours of symptom onset for treatment or after exposure for prophylaxis. 1
Approved Indications and Age Restrictions
- Xofluza is FDA-approved for treatment of acute uncomplicated influenza A and B in patients ≥12 years of age who have been symptomatic for ≤48 hours 2, 3, 4
- For prophylaxis, Xofluza is approved only for patients ≥12 years of age who weigh more than 40 kg 5
- The prophylaxis dosing is identical to the treatment dosing—the same single weight-based dose 5
Weight-Based Dosing (Tablets)
- Patients weighing 20 kg to <80 kg: One 40 mg tablet as a single dose 1
- Patients weighing ≥80 kg: One 80 mg tablet as a single dose 1
Oral Suspension Dosing
For patients unable to swallow tablets or requiring enteral administration, Xofluza is available as an oral suspension (2 mg/mL after constitution): 1
- Patients weighing <20 kg: 2 mg/kg as a single dose 1
- Patients weighing 20 kg to <80 kg: 40 mg (20 mL) as a single dose 1
- Patients weighing ≥80 kg: 80 mg (40 mL, requiring two bottles) as a single dose 1
Critical Administration Instructions
- Timing: Administer as soon as possible within 48 hours of symptom onset for treatment or following contact with an influenza-infected individual for prophylaxis 1
- Food interactions: Avoid coadministration with dairy products, calcium-fortified beverages, polyvalent cation-containing laxatives, antacids, or oral supplements containing calcium, iron, magnesium, selenium, or zinc, as these significantly reduce baloxavir absorption 1
- Oral suspension preparation: Must be used within 10 hours after constitution, as the product contains no preservative 1
Renal and Hepatic Impairment
- No dosage adjustment is needed in patients with mild-to-moderate hepatic or renal impairment 4
Clinical Efficacy Context
- Baloxavir demonstrates similar time to symptom alleviation compared to oseltamivir (median 53.7 hours vs 80.2 hours compared to placebo) 6
- Baloxavir achieves significantly greater viral load reduction at 1 day post-treatment compared to both oseltamivir and placebo 6, 7
- The single-dose regimen offers a major adherence advantage over the 5-day twice-daily oseltamivir regimen 2, 3
Important Safety Considerations
- Common adverse events include diarrhea, bronchitis, nausea, nasopharyngitis, and headache, occurring in approximately 20.7% of recipients 6, 4
- Resistance concern: Polymerase acidic protein variants with reduced susceptibility to baloxavir emerged in 9.7% of treated patients in phase 3 trials 6
- Despite resistance emergence, baloxavir remains well-tolerated with only mild adverse events reported 3