Maximum Rectal Dose of Diclofenac for a 3-Year-Old Child (22 kg)
For a 3-year-old child weighing 22 kg, the maximum single rectal dose of diclofenac is 22 mg (1 mg/kg), administered every 8 hours, with a maximum daily dose of 66 mg (3 mg/kg/day). 1
Dosing Algorithm
Single Dose Calculation
- Standard rectal dose: 1 mg/kg per dose 2, 1
- For this 22 kg child: 22 mg per dose
- This dose is based on pharmacokinetic modeling demonstrating that 0.5 mg/kg rectally yields equivalent drug exposure to standard adult dosing 1
Dosing Interval
- Administer every 8 hours 2
- Some practitioners use 8-hourly dosing (53% in clinical practice surveys), though the pharmacokinetic data supports this interval 2
Maximum Daily Dose
- Total daily maximum: 3 mg/kg/day (66 mg for this child) 1
- This translates to three doses maximum in 24 hours at the 1 mg/kg dosing
Important Clinical Caveats
Absorption Concerns with Rectal Route
- Rectal diclofenac has erratic and less reliable absorption compared to oral or intravenous routes 3, 1
- Bioavailability of rectal diclofenac is only 35% compared to other formulations 1
- This unpredictable absorption means some children may receive inadequate analgesia while others risk accumulation with repeated dosing 3
Hydration Status
- Ensure adequate hydration before administering diclofenac, as NSAIDs carry renal risks in dehydrated patients 3
- This is particularly critical in children aged 3-6 years who may have reduced fluid intake due to illness 3
Preferred Alternative
- Oral ibuprofen (10 mg/kg every 6-8 hours) is generally preferred over rectal diclofenac when the child can tolerate oral medications, due to more consistent absorption and established safety data 4, 3
- Rectal administration should be reserved for situations where oral intake is not possible (active vomiting, perioperative settings) 4
Practical Dosing Summary
For this specific 22 kg child:
- Single dose: 22 mg rectally
- Frequency: Every 8 hours
- Maximum daily: 66 mg (three doses)
- Duration: Short-term use only 3