Pediatric Syrup Dosing for Acetaminophen and Ibuprofen
Acetaminophen (Tylenol) Dosing
For acetaminophen, use 15 mg/kg per dose every 4-6 hours, with a maximum of 5 doses in 24 hours, as the standard 10 mg/kg dose fails to achieve therapeutic plasma concentrations needed for effective antipyresis. 1, 2
Weight-Based Dosing Strategy
- Single dose: 15 mg/kg every 4-6 hours 1
- Maximum daily dose: 75 mg/kg/day (not to exceed adult maximum) 1
- Pharmacokinetic modeling demonstrates that 10 mg/kg doses produce peak plasma concentrations of only 6.38-8.55 μg/mL, which falls below the therapeutic range of 10-20 μg/mL required for antipyresis 2
- The 15 mg/kg dose achieves plasma concentrations of 9.57-12.8 μg/mL, which approaches therapeutic levels 2
Critical Dosing Pitfall
- Age-based dosing leads to underdosing in up to 30% of children 2
- Weight-based calculations are essential, as children differ from adults only in size (once past 2 years of age), not in drug metabolism 3
- Manufacturer age-based recommendations (e.g., 160 mg for ages 2-3 years) are only effective for children at the lower end of the weight range (10.9 kg) and inadequate for heavier children in that age bracket 2
Ibuprofen (Advil) Dosing
For ibuprofen, administer 10 mg/kg per dose every 6-8 hours for pain and fever, with a maximum single dose of 400 mg and maximum daily dose of 40 mg/kg (not exceeding 1200 mg/day for over-the-counter use). 4
Dosing Parameters
- Single dose: 10 mg/kg every 6-8 hours 4
- Maximum single dose: 400 mg 4
- Maximum daily dose: 40 mg/kg/day or 1200 mg/day (whichever is less) for non-prescription use 4
- For prescription use in chronic conditions, doses up to 3200 mg/day may be used in adults, but pediatric dosing should remain weight-based 4
Administration Considerations
- Administer with food or milk if gastrointestinal complaints occur 4
- In controlled trials, doses greater than 400 mg were no more effective than 400 mg for acute pain 4
- For dysmenorrhea in adolescents: 400 mg every 4 hours as needed 4
Key Principles for All Pediatric Syrup Dosing
Size and Maturation Factors
- Children ≥2 years are pharmacokinetically mature and differ from adults only in size 3
- Neonates and infants (<2 years) have immature drug elimination pathways and require different dosing considerations 3
- Simple weight-based scaling (mg/kg) from adult doses results in doses that are too small for children because drug elimination does not change in direct proportion to weight 3
Common Dosing Errors to Avoid
- Never use age-based dosing alone—always calculate based on current weight 1, 2
- Avoid underdosing by using the lower end of recommended ranges (e.g., 10 mg/kg acetaminophen) 2
- Do not assume pediatric formulations automatically provide correct dosing—verify the concentration and calculate the volume needed 5
- Absence of pediatric-specific dosage forms increases potential for serious dosing errors 5