Oseltamivir Dosing for 7-Month-Old Infant Weighing 5.89 kg
For a 7-month-old infant weighing 5.89 kg, the recommended dose of oseltamivir (Fluvir) is 3 mg/kg per dose twice daily for treatment (5 days) or 3 mg/kg per dose once daily for prophylaxis (10 days), which calculates to approximately 18 mg (3 mL of 6 mg/mL oral suspension) per dose. 1, 2
Weight-Based Dosing Calculation
- Treatment dose: 3 mg/kg × 5.89 kg = 17.67 mg per dose, administered twice daily 1
- Prophylaxis dose: 3 mg/kg × 5.89 kg = 17.67 mg per dose, administered once daily 1
- Volume using 6 mg/mL suspension: 17.67 mg ÷ 6 mg/mL = approximately 3 mL per dose 2
Age-Specific Considerations
- This infant falls into the 3-11 months age category, for which the FDA-approved dosing is 3 mg/kg per dose 1, 2
- Oseltamivir is FDA-approved for treatment in children as young as 2 weeks of age 1, 2
- The 3 mg/kg dosing applies to term infants aged 0-8 months 1
Formulation and Administration
- Use the oral suspension formulation with a concentration of 6 mg/mL 1, 2
- Administer with or without food, though tolerability may be enhanced when taken with food 2
- Use an appropriate dosing device that can accurately measure small volumes (3 mL) 2
Treatment Duration
- Treatment course: 5 days of twice-daily dosing 1, 2
- Prophylaxis duration: 10 days of once-daily dosing for post-exposure prophylaxis 1, 2
- Initiate treatment within 48 hours of symptom onset for optimal efficacy 2
Common Pitfalls to Avoid
- Do not use the older weight-based categories (≤15 kg = 30 mg) that apply only to children ≥12 months of age 1
- Do not round to fixed doses for infants under 12 months; always calculate based on actual weight using 3 mg/kg 1
- Ensure proper measurement using a calibrated oral dosing device that accurately measures 3 mL 2
- This is NOT a preterm infant dosing scenario (which would require 1.0-1.5 mg/kg depending on postmenstrual age) 1