What is the recommended dose and duration of diclofenac (Nonsteroidal Anti-Inflammatory Drug (NSAID)) for an 11-year-old child, weighing 30-50 kilograms (kg), with no significant medical history, such as gastrointestinal (GI) bleeding or impaired renal function, following musculoskeletal trauma?

Diclofenac Dosing for an 11-Year-Old Child Following Musculoskeletal Trauma

For an 11-year-old child (30-50 kg) with musculoskeletal trauma, administer diclofenac 1 mg/kg orally every 8 hours for 3-5 days, not exceeding 75 mg per day.

Dosing Recommendations

Optimal Dose and Frequency

• Administer 1 mg/kg per dose orally every 8 hours 1, 2
• For a child weighing 30-50 kg, this translates to 30-50 mg per dose 2
• Maximum daily dose: 75 mg (three doses of 25 mg or adjusted based on weight) 3
• The 8-hourly dosing interval is the most commonly employed schedule in pediatric practice, used by 53% of pediatric anesthesiologists 1

Duration of Treatment

• Limit treatment to 3-5 days for acute musculoskeletal trauma 3
• A maximum treatment duration of 5 days for pain is recommended for non-prescription use, which should guide acute trauma management 3
• Avoid prolonged use beyond this timeframe to minimize gastrointestinal and renal risks 4

Route of Administration

Preferred Route

• Oral administration is preferred (used by 81% of practitioners) for conscious, cooperative children following trauma 1
• Oral diclofenac has a bioavailability of approximately 0.36 for suspension formulations 2
• Rectal administration (bioavailability 0.63) can be considered if oral route is not feasible, though it is less commonly used 1, 2

Pharmacokinetic Considerations

Onset and Duration

• Peak plasma concentration occurs within 30 minutes of oral administration 3
• Duration of action: 4-6 hours, supporting the 8-hourly dosing schedule 3
• Terminal half-life is 1-2 hours, limiting drug accumulation risk 3

Absorption and Metabolism

• Absorption is rapid and complete when given orally 5
• Diclofenac undergoes extensive hepatic biotransformation to glucuronide and sulfate conjugates 5
• No dosage adjustment is required for children based on age alone in the 1-12 year range 5, 2

Safety Considerations

Common Pitfalls to Avoid

• Do not exceed 75 mg total daily dose in this age group to prevent increased risk of gastrointestinal and renal adverse effects 3
• Avoid administration with aspirin, as it can lead to significant drug interactions 5
• Monitor for gastrointestinal symptoms, though diclofenac rarely produces serious gastrointestinal ulceration compared to other NSAIDs 4
• Ensure adequate hydration during treatment, as NSAIDs can affect renal function in dehydrated states 4

Contraindications

• Do not use in children with active gastrointestinal bleeding or peptic ulcer disease 4
• Avoid in children with significant renal impairment (though conjugate accumulation primarily occurs in end-stage renal disease) 5
• Exercise caution in children taking lithium, digoxin, methotrexate, or cyclosporin due to documented drug interactions 5

Clinical Efficacy

Evidence for Acute Pain

• Diclofenac is an effective, opioid-sparing analgesic for acute pain in children 2
• It has a fast onset and long duration of action as an analgesic 4
• Single doses of 25 mg (two 12.5 mg tablets) are at least as effective as ibuprofen 400 mg in comparable acute pain conditions 3

Practical Implementation

• Administer with meals to improve gastrointestinal tolerability, though this is not mandatory 2
• Diclofenac is available as tablets and oral suspension (6 mg/mL concentration) 2
• For a 40 kg child: administer 40 mg (approximately 6.7 mL of suspension or one 50 mg tablet adjusted) every 8 hours 2