Naproxen Dosing for a 45 kg Child According to BNFC
For a child weighing 45 kg, the recommended naproxen dose according to the British National Formulary for Children (BNFC) is 500 mg twice daily for most indications.
Dosage Calculation
The appropriate naproxen dose for children is weight-based, with different considerations depending on the child's weight and the indication:
- For a 45 kg child, the dosing falls into the adult dosing category since the child weighs more than 40 kg 1
- The standard adult dose of 500 mg twice daily is appropriate for this weight 1
- The total daily dose should not exceed 1000 mg of naproxen for maintenance therapy 1
Indication-Specific Dosing
The naproxen dosage may vary slightly depending on the specific indication:
- Rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis: 500 mg twice daily 1
- Juvenile arthritis: Approximately 10 mg/kg/day given in 2 divided doses (450 mg total daily for a 45 kg child) 1
- Acute pain, primary dysmenorrhea: Initial 500 mg, followed by 500 mg every 12 hours or 250 mg every 6-8 hours as required 1
- Acute gout: Initial 750 mg, followed by 250 mg every 8 hours until attack subsides 1
Administration Considerations
- Naproxen should be taken with food to minimize gastrointestinal side effects
- The morning and evening doses do not have to be equal in size 1
- Use the lowest effective dose for the shortest duration consistent with treatment goals to minimize adverse effects 1
Important Precautions
- Monitor for gastrointestinal adverse effects, particularly in prolonged use
- Use caution in patients with renal or hepatic impairment
- Naproxen is not recommended for patients with moderate to severe renal impairment (creatinine clearance < 30 mL/min) 1
- For long-term administration, the dose may be adjusted up or down depending on clinical response 1
Formulation Considerations
- Different formulations (tablets, suspension) are not necessarily bioequivalent 1
- For a 45 kg child, tablets are appropriate rather than suspension, which is typically used for smaller children 1
The dosing recommendation aligns with the principle that children weighing more than 40 kg should be dosed as adults, which is consistent with standard pediatric dosing practices for many medications.