Is 8ml of 12mg/ml oseltamivir suspension twice daily the correct dose for an 8kg infant?

Dosing Calculation Error: 8ml Twice Daily is Incorrect for an 8kg Infant

No, 8ml of 12mg/ml oseltamivir suspension twice daily is NOT the correct dose for an 8kg infant. This would deliver 96mg per dose (192mg daily), which is dangerously excessive and approximately 3 times higher than the recommended dose.

Correct Dosing for an 8kg Infant

For an 8-month-old term infant weighing 8kg, the appropriate oseltamivir dose is 3 mg/kg per dose twice daily 1. This calculates to:

• 24mg per dose (8kg × 3mg/kg = 24mg)
• Given twice daily for 5 days

Volume Calculation Based on Suspension Concentration

Critical Error in Your Question

You mentioned a "12mg/ml" concentration, but the standard commercially available oseltamivir suspension is 6mg/ml, not 12mg/ml 1. The 12mg/ml concentration was phased out years ago to reduce frothing when shaken 1.

If Using Standard 6mg/ml Suspension:

• 4ml twice daily delivers the correct 24mg dose 1

If You Actually Have 12mg/ml Suspension (Old Stock):

• 2ml twice daily would deliver 24mg 1

Why 8ml is Dangerous

If you gave 8ml of a 12mg/ml suspension:

• 8ml × 12mg/ml = 96mg per dose
• This is 4 times the recommended dose for this infant
• Risk of significant overdose and adverse effects including gastrointestinal toxicity 2, 3

Age-Specific Dosing Algorithm for Infants

For term infants 0-8 months old:

• Dose: 3 mg/kg per dose twice daily 1
• Duration: 5 days for treatment

For infants 9-11 months old:

• Dose: 3.5 mg/kg per dose twice daily 1

For children ≥12 months:

• Weight-based unit dosing applies 1:
  • ≤15 kg: 30mg twice daily (5ml of 6mg/ml suspension)

  • 15-23 kg: 45mg twice daily (7.5ml of 6mg/ml suspension)

  • 23-40 kg: 60mg twice daily (10ml of 6mg/ml suspension)

  • 40 kg: 75mg twice daily (12.5ml of 6mg/ml suspension)

Practical Administration Guidance

• Use an appropriate measuring device such as a 3-ml or 5-ml oral syringe for infants under 1 year, not the syringe supplied with the medication 1
• Administration with meals may improve gastrointestinal tolerability 1, 2
• Confirm the concentration on your bottle label before calculating the volume 1

Common Pitfall to Avoid

The most common dosing error is confusing the dose in mg with the volume in ml. Always perform a two-step calculation:

1. Calculate the dose in mg based on weight (3 mg/kg for this infant = 24mg)
2. Calculate the volume needed based on suspension concentration (24mg ÷ 6mg/ml = 4ml)