What is the recommended dose of naproxen (Nonsteroidal Anti-Inflammatory Drug) according to the British National Formulary for Children (BNFC) for a 14-year-old girl?

Naproxen Dosing for a 14-Year-Old Girl According to BNFC

The recommended dose of naproxen for a 14-year-old girl according to the British National Formulary for Children (BNFC) is 5 to 7.5 mg/kg every 12 hours. 1

Dosing Calculation and Administration

• For a 14-year-old girl (who would typically weigh more than 40 kg), the appropriate naproxen dosage would be calculated based on her weight 1
• If the patient weighs more than 40 kg, the maximum dose would be 500 mg twice daily 2
• For juvenile arthritis specifically, the recommended total daily dose is approximately 10 mg/kg given in 2 divided doses (i.e., 5 mg/kg given twice a day) 2
• Naproxen suspension is recommended for more precise weight-based dosing in pediatric patients 2

Indications and Administration Considerations

• Naproxen can be used for management of pain, inflammatory conditions, and primary dysmenorrhea in adolescents 2
• The medication can be administered orally using a convenient once or twice daily regimen 3
• Absorption is rapid and complete when given orally 4
• Naproxen tablets and suspension appear to be bioequivalent in fasting children ages 8 to 14 years 5

Pharmacokinetic Considerations

• The area under the plasma concentration-time curve (AUC) of naproxen is linearly proportional to doses up to 500 mg 4
• At doses greater than 500 mg, there is an increase in the unbound fraction of drug, leading to increased renal clearance 4
• Elimination of naproxen may be more rapid in children compared to adults 5

Safety Considerations and Monitoring

• Common adverse effects include gastrointestinal discomfort, dyspepsia, and abdominal pain 1
• Consider combining with a proton pump inhibitor or histamine H2 blocker if GI symptoms occur 1
• Naproxen should be used with caution in patients with renal impairment 2
• Monitor for signs of GI bleeding, especially if there is a history of NSAID-associated upper GI tract bleeding 1
• Avoid use in patients with severe hepatic impairment 1

Special Dosing Situations

• For acute pain management, an initial dose of 500 mg followed by 250 mg every 6-8 hours as required may be appropriate, with total daily dose not exceeding 1250 mg initially and 1000 mg thereafter 2
• For primary dysmenorrhea, the same dosing approach as for acute pain management is recommended 2

Practical Administration Tips

• Naproxen can be taken with food to reduce gastrointestinal side effects 3
• The morning and evening doses do not have to be equal in size 2
• Administration more frequently than twice daily is generally not necessary for sustained therapeutic effect 2