What is the appropriate dose of ibuprofen (Motrin) in nanograms for a 102‑lb (46‑kg) person?

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Ibuprofen Dosing for a 102-lb Patient

For a patient weighing 102 lbs (46 kg), administer 400–500 mg of ibuprofen per dose, given every 8 hours, with a maximum of 3 doses in 24 hours. 1

Weight-Based Calculation

  • The standard pediatric dose is 10 mg/kg per dose, which equals 460 mg for this 46-kg patient 1, 2
  • Since this patient weighs more than 40 kg (88 lbs), adult dosing guidelines apply 2, 3
  • Round the calculated 460 mg to a practical tablet strength of 400–500 mg per dose 1

Dosing Schedule and Maximum Limits

  • Administer every 8 hours (three times daily) with a maximum of 3 doses in 24 hours 1, 2
  • The maximum daily dose is 40 mg/kg/day, which equals approximately 1,840 mg/day for this patient 1
  • For patients in this weight range, the single-dose ceiling is typically 600 mg; the calculated 460 mg dose is safely below this threshold 1
  • The FDA-approved maximum total daily dose for adults is 3,200 mg, though most patients respond adequately to lower doses 3

Route of Administration

  • Oral administration is the preferred route for routine outpatient care 1
  • Administer with meals or milk if gastrointestinal complaints occur 3

Critical Safety Considerations

  • Monitor for gastrointestinal upset, dizziness, and rash 2
  • Use with caution in patients with peptic ulcer disease, renal impairment, cardiovascular disease, or bleeding disorders 2
  • Avoid combining with other NSAIDs (such as ketorolac/Toradol) due to additive toxicity risks without additional analgesic benefit 4
  • Be aware of "hidden sources" of NSAIDs in combination over-the-counter medications 2

Common Pitfalls to Avoid

  • Do not exceed the maximum daily dose of 40 mg/kg/day (approximately 1,840 mg for this patient) 1
  • Avoid concurrent use with other NSAIDs or acetaminophen-containing products without dose adjustment 2
  • Ensure adequate hydration, as short-term ibuprofen use is safe when special attention is given to patient hydration 5

Duration of Action

  • Ibuprofen 400 mg provides analgesia for at least 6 hours, which supports the every-8-hour dosing interval 6
  • Maximum temperature reduction occurs 3–4 hours after administration 7

References

Guideline

Ibuprofen Dosing Guidelines for Pediatric Patients

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Guideline

Ibuprofen Dosing Guidelines for Adolescents

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Safe Use of Toradol After Ibuprofen

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Research

Review of the analgesic efficacy of ibuprofen.

International journal of clinical practice. Supplement, 2003

Research

A general overview of the use of ibuprofen in paediatrics.

International journal of clinical practice. Supplement, 2003

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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