What is the recommended dose of ibuprofen (Nonsteroidal Anti-Inflammatory Drug (NSAID)) for a patient weighing 39 kilograms (kg)?

Ibuprofen Dosing for a 39 kg Patient

For a 39 kg patient, the recommended ibuprofen dose is 400 mg orally every 6 hours, with a maximum daily dose of 2400 mg for anti-inflammatory effects or 1200 mg for mild-moderate pain. 1

Weight-Based Dosing Calculation

• Standard pediatric dosing for ibuprofen is 5-10 mg/kg per dose 1
• For a 39 kg patient, this translates to:
  • Minimum dose: 195 mg (5 mg/kg × 39 kg) 1
  • Maximum dose: 390 mg (10 mg/kg × 39 kg) 1
• In practice, round to the nearest available formulation: 400 mg per dose 1

Dosing Frequency and Maximum Daily Limits

• Administer every 6 hours as needed for pain or fever 1
• Maximum daily dose: 2400 mg/day for anti-inflammatory conditions 2
• For acute mild-moderate pain (headache, dental pain, dysmenorrhea): limit to 1200 mg/day for ≤10 days 2
• Avoid exceeding 2400 mg per day regardless of indication 1

Route of Administration Considerations

Oral Administration (Preferred)

• 400 mg orally every 6 hours is the standard approach 1
• Absorption is enhanced with certain formulations (lysine, arginine, potassium salts) 3
• Taking with food may improve gastrointestinal tolerability 1

Intravenous Administration (Hospital Settings Only)

• If IV route is necessary: 400-800 mg IV every 6 hours 4
• Maximum IV dose: 800 mg per dose, 3200 mg/day 4
• Standard infusion time is 30 minutes, though 5-10 minute infusions are well-tolerated 5
• IV ibuprofen 800 mg every 6 hours reduces opioid requirements by 22% in postoperative pain 4

Clinical Efficacy Evidence

• Ibuprofen 400 mg provides analgesia for at least 6 hours, superior to 200 mg (4-6 hours) or paracetamol 3
• Ibuprofen 400 mg is as effective as aspirin 600-900 mg/day for moderate pain 3
• The smallest clinically useful dose is 200 mg, but 400 mg is more appropriate for a 39 kg patient 3

Safety Considerations and Contraindications

Absolute Contraindications

• Active peptic ulcer disease or gastrointestinal bleeding 1
• Aspirin/NSAID-induced asthma 1
• Perioperative period in coronary artery bypass graft surgery 5
• Pregnancy (third trimester) 1

Relative Contraindications and Cautions

• Use with caution in patients with cardiovascular disease, hypertension, or renal impairment 6
• Avoid in patients with hepatic dysfunction 6
• Concomitant anticoagulant use increases bleeding risk 3-6 fold 6

Common Pitfalls in Dosing

• Parents frequently misdose antipyretics: 62% give inaccurate acetaminophen doses, 26% give inaccurate ibuprofen doses 7
• Infants <1 year are at highest risk for misdosing (RR 1.40) 7
• Weight-based dosing reduces misdosing errors (RR 0.71) 7
• Always calculate dose based on actual body weight, not age alone 7

Monitoring Requirements

• For chronic use (>10 days): monitor blood pressure, renal function (BUN, creatinine), liver function, CBC, and fecal occult blood every 3 months 6
• Discontinue if BUN or creatinine doubles 6
• Discontinue if liver function tests increase to 3× upper limit of normal 6

Alternative Considerations

• If two NSAIDs fail in succession, switch to opioid analgesics or non-pharmacologic interventions rather than trialing additional NSAIDs 6
• Ibuprofen has lower GI toxicity than aspirin and similar GI effects to paracetamol at OTC doses 2