What is the recommended dose of naproxen (nonsteroidal anti-inflammatory drug (NSAID)) for pediatric patients of different age groups?

Naproxen Dosing in Pediatric Patients

For children aged 2 years and older with juvenile idiopathic arthritis, naproxen should be dosed at 10 mg/kg/day divided into two doses (5 mg/kg per dose twice daily), with a maximum total daily dose not exceeding 15 mg/kg/day. 1

Age-Specific Dosing Guidelines

Children Under 2 Years

• Naproxen is not recommended for children under 2 years of age, as safety and effectiveness have not been established in this age group 1

Children 2 Years and Older

For Juvenile Idiopathic Arthritis (FDA-approved indication):

• Dose: 10 mg/kg/day divided into 2 doses (5 mg/kg per dose given twice daily) 1
• Maximum daily dose: 15 mg/kg/day 1
• Administer as naproxen suspension for accurate weight-based dosing 1

For Other Pediatric Conditions (off-label):

• Single doses of 2.5 to 5 mg/kg are well tolerated 1
• Total daily dose should not exceed 15 mg/kg/day 1
• These recommendations are based on experience in juvenile arthritis and other pediatric use 1

Pharmacokinetic Considerations

Absorption and half-life in children aged 5-16 years are similar to adults:

• Peak plasma levels after a 5 mg/kg single dose in pediatric patients (ages 5-16) are comparable to those in adults receiving 500 mg 1
• Terminal half-life appears similar between pediatric and adult patients 1
• Naproxen is rapidly absorbed with peak levels at 2-4 hours and elimination half-life of 12-17 hours 1
• Steady-state levels are reached in 4-5 days 1

Clinical Evidence and Tolerability

Recent clinical trial data support safety in adolescents:

• A 6-month study of fixed-dose naproxen/esomeprazole in JIA patients aged 12-16 years demonstrated good tolerability, with 80.4% experiencing at least one treatment-emergent adverse event, though most were mild or moderate 2
• Only 8.7% discontinued due to adverse events 2
• ACR Pediatric-30 response was achieved in 47.1% of patients by month 6 2

Historical data confirm comparable pharmacokinetics:

• Studies in children (mean age 10.8 years) showed no significant difference in peak blood levels and half-life compared to adults, supporting twice-daily dosing 3

Important Safety Considerations

Renal function monitoring is critical:

• Naproxen is substantially excreted by the kidney (approximately 95% in urine) 1
• Not recommended in patients with moderate to severe renal impairment (creatinine clearance <30 mL/min) 1

Gastrointestinal protection:

• Consider concomitant proton pump inhibitor therapy to reduce risk of gastric ulcers, particularly with chronic use 2

Pregnancy and lactation:

• Avoid use during pregnancy, especially late pregnancy, due to risk of premature ductus arteriosus closure 1
• Naproxen is found in breast milk at approximately 1% of maximum maternal plasma concentration; use in nursing mothers should be avoided 1

Common Pitfalls to Avoid

• Do not use adult dosing in children - always calculate weight-based doses 1
• Do not exceed 15 mg/kg/day total daily dose in pediatric patients 1
• Do not use in children under 2 years - safety not established 1
• Do not assume all NSAIDs have the same pediatric dosing - naproxen's longer half-life allows twice-daily dosing unlike some other NSAIDs 1, 3