What is the dosing frequency and volume of oseltamivir (Tamiflu) for an infant when a 30mg capsule is opened and mixed with a liquid?

Oseltamivir (Tamiflu) Dosing for Infants Using 30mg Capsules

For an infant, a 30mg oseltamivir capsule should be opened and mixed with a sweetened liquid, with dosing of 3mg/kg given twice daily for treatment or once daily for prophylaxis. 1

Dosing Based on Age

For Treatment (5 days duration)

• 0-3 months: 3mg/kg twice daily 1
  • If weight unknown: 12mg (2mL of 6mg/mL suspension) twice daily 1
• 4-5 months: 3mg/kg twice daily 1
  • If weight unknown: 17mg (2.8mL of 6mg/mL suspension) twice daily 1
• 6-11 months: 3mg/kg twice daily 1
  • If weight unknown: 24mg (4mL of 6mg/mL suspension) twice daily 1

For Prophylaxis (10 days duration)

• 3-11 months: 3mg/kg once daily 1
• 0-3 months: Not recommended unless situation judged critical 1

Preparation Instructions

1. Open the 30mg capsule and mix contents with a sweetened liquid to mask the bitter taste 1
2. Use an appropriate measuring device such as a 3mL or 5mL oral syringe for accurate dosing 1
3. Calculate the exact volume needed based on the child's weight (3mg/kg) 1
4. Administer twice daily for treatment or once daily for prophylaxis 1

Special Considerations

• Weight-based dosing is preferred over age-based dosing whenever possible 1
• Preterm infants require lower doses due to immature renal function 1, 2
  • <38 weeks postmenstrual age: 1mg/kg twice daily 1, 2
  • 38-40 weeks postmenstrual age: 1.5mg/kg twice daily 1, 2

  • 40 weeks postmenstrual age: 3mg/kg twice daily 1, 2

Administration Tips

• Give with food to improve gastrointestinal tolerability 2, 3
• For infants younger than 1 year, use an appropriate measuring device such as a 3mL or 5mL oral syringe 1
• Ensure the entire dose is consumed 3
• Treatment should be initiated as soon as possible after symptom onset, ideally within 48 hours 2

Common Side Effects

• Vomiting (more common in children) 4
• Nausea 4
• Diarrhea 2

Important Cautions

• The FDA-approved unit dose of 30mg for children 12-23 months may result in suboptimal exposure in some children 5
• Pharmacokinetic studies show that infants as young as 1 year can metabolize and excrete oseltamivir efficiently, but clearance is faster in younger children 6, 7
• For infants with renal impairment, dose adjustment is necessary 2, 3

The dosing recommendations are based on the most recent guidelines from the American Academy of Pediatrics and FDA labeling, which prioritize appropriate therapeutic exposure while minimizing adverse effects to improve outcomes in infants with influenza.