What is the recommended dose of diclofenac (Nonsteroidal Anti-Inflammatory Drug (NSAID)) for a 4-6 year old, 22 kg child with no specified medical history, for rectal administration?

Rectal Diclofenac Dosing for a 4-6 Year Old Child (22 kg)

For rectal administration of diclofenac in a 22 kg child aged 4-6 years, give 12.5 mg (0.5 mg/kg) as a single dose, which can be repeated every 8 hours if needed, not exceeding 37.5 mg (1.5 mg/kg) per day. 1

Evidence-Based Dosing Recommendation

The most rigorous pharmacokinetic data comes from a 2011 meta-analysis that specifically evaluated diclofenac dosing across different routes in children aged 1-12 years 1. This study analyzed 111 children and established that:

• Rectal suppositories require 0.5 mg/kg per dose to achieve therapeutic drug exposure equivalent to standard adult dosing 1
• For your 22 kg child, this equals 11 mg per dose (round to nearest available suppository strength, typically 12.5 mg)
• The bioavailability of rectal diclofenac is 0.63, which is higher than oral suspension but requires appropriate dosing adjustment 1

Dosing Interval and Maximum Daily Dose

• Administer every 8 hours as needed for pain or fever 2
• Maximum daily dose: 1.5 mg/kg/day (approximately 33 mg for a 22 kg child, or three 12.5 mg doses) 1
• This dosing interval is supported by clinical practice patterns where 53% of pediatric anesthesiologists use 8-hourly dosing 2

Clinical Effectiveness Considerations

Rectal diclofenac demonstrates superior antipyretic efficacy compared to rectal acetaminophen in the first hour after administration 3:

• Temperature reduction with diclofenac: 1.73°C vs 0.65°C with acetaminophen at one hour 3
• This makes it particularly effective for acute fever management when oral administration is not feasible 3

Important Safety Caveats

• Diclofenac is licensed for children over 1 year of age, making it appropriate for your 4-6 year old patient 2
• Rectal administration is commonly used (80% of pediatric anesthesiologists use this route) and is appropriate when oral intake is restricted or the child is vomiting 2, 4
• Do not use in children with renal impairment, dehydration, or bleeding disorders as NSAIDs carry these contraindications 5
• Monitor for gastrointestinal side effects, though diclofenac has a favorable safety profile compared to other NSAIDs 5

Practical Administration

• Use commercially available 12.5 mg suppositories (closest to the calculated 11 mg dose)
• Rectal absorption is complete but may be slower than oral routes 1
• The drug has a relatively short elimination half-life, limiting accumulation risk 5
• No dosage adjustment needed based on age alone within the 1-12 year range 6