Diclofenac Dosing in Children
For children aged 1-12 years, the recommended dose of diclofenac is 1 mg/kg orally, 0.5 mg/kg rectally, or 0.3 mg/kg intravenously, based on pharmacokinetic modeling that achieves equivalent drug exposure to adult dosing. 1
Route-Specific Dosing Recommendations
Oral Administration
- 1 mg/kg per dose is the recommended oral dose for children aged 1-12 years 1
- This dose can be administered every 8 hours, which is the most commonly used dosing interval in clinical practice 2
- Maximum daily dose should not exceed 150 mg/day in children under 10 years 2
Rectal Administration
- 0.5 mg/kg per dose is recommended for rectal suppositories 1
- Rectal bioavailability is approximately 63%, significantly higher than oral suspension (36%) 1
- This route is commonly used intraoperatively and postoperatively 2
Intravenous Administration
- 0.3 mg/kg per dose for intravenous administration 1
- This lower dose accounts for 100% bioavailability compared to oral routes 1
Age and Weight Considerations
Minimum Age
- Diclofenac is licensed for use in children over 1 year of age for juvenile rheumatoid arthritis 2
- Despite licensing restrictions, 86% of pediatric anesthesiologists report using NSAIDs in infants, though this represents off-label use 2
Dosing Intervals
- Every 8 hours is the most commonly employed dosing schedule (used by 53% of practitioners) 2
- This interval balances efficacy with safety considerations
Pharmacokinetic Rationale
The recommended doses are based on a comprehensive pharmacokinetic meta-analysis of 111 children that demonstrated:
- Clearance of 16.5 L/h/70 kg 1
- These weight-adjusted doses achieve an area under the curve (AUC) equivalent to a 50-mg adult dose 1
- A three-compartment model best describes diclofenac disposition in children 1
Combination Therapy
When combined with acetaminophen:
- Diclofenac 1 mg/kg with acetaminophen 15 mg/kg achieves equivalent analgesia to acetaminophen 30 mg/kg alone 3
- Drug effects are additive, not synergistic 3
- Combination therapy allows lower doses of both medications while maintaining analgesic efficacy 3
Special Populations
Renal and Hepatic Impairment
- Dosage adjustments may not be required for children with various disease states, as conjugate accumulation has not been demonstrated to be clinically significant 4
- However, caution is warranted as excretion of conjugates is related to renal function 4
Elderly Considerations (Not Applicable to Pediatrics)
- No specific pediatric age-related dose reductions are recommended beyond the weight-based dosing 4
Clinical Context and Safety
Common Pitfalls
- Avoid extrapolating adult dosing directly - the 1 mg/kg oral dose in children is specifically derived from pediatric pharmacokinetic data, not adult studies 1
- Do not exceed maximum daily doses - particularly important in younger children where 150 mg/day ceiling applies 2
- Consider bioavailability differences - rectal and oral routes have significantly different absorption profiles requiring different doses 1