Mefenamic Acid Dosing for a 9-Year-Old Child Weighing 37 kg
For a 9-year-old child weighing 37 kg, the recommended dose of mefenamic acid is 6 mg/kg per dose, which equals approximately 222 mg (can be rounded to 200-250 mg depending on available formulations), given every 6-8 hours as needed for pain or fever. 1
Weight-Based Dosing Calculation
- The standard pediatric dose of mefenamic acid is 6 mg/kg per dose 1
- For a 37 kg child: 37 kg × 6 mg/kg = 222 mg per dose
- This dose can be administered every 6-8 hours as needed 1
- The maximum daily dose should not exceed 1000 mg in children 2
Clinical Context and Evidence
The 6 mg/kg dosing is supported by a recent randomized controlled trial that demonstrated mefenamic acid at this dose has equivalent antipyretic efficacy to high-dose paracetamol (20 mg/kg) and superior efficacy to standard-dose paracetamol (15 mg/kg) 1. The study showed that mefenamic acid achieved fever reduction in approximately 85 minutes with minimal adverse effects 1.
An older study using 4 mg/kg dosing showed adequate antipyretic effect, but the more recent evidence supports 6 mg/kg as the optimal dose for both antipyretic and analgesic effects 2, 1.
Practical Administration Guidelines
- Round to available formulations: If mefenamic acid is available as 250 mg capsules, administering one capsule (250 mg) would be appropriate and safe for this child 1
- Frequency: Administer every 6-8 hours as needed, not to exceed 4 doses in 24 hours 1
- Take with food to minimize gastrointestinal side effects 1
Important Clinical Considerations
- Reserve for appropriate indications: Mefenamic acid should be used for pain management or when anti-inflammatory effects are needed, rather than as a first-line antipyretic 1
- Duration: Limit use to 7 days or less for acute pain management 3
- Monitor for adverse effects: Watch for gastrointestinal symptoms, though these were negligible in clinical trials at this dose 1
- Contraindications: Avoid in children with known NSAID hypersensitivity, active peptic ulcer disease, or significant renal impairment 3
Common Pitfalls to Avoid
- Do not underdose: Using the older 4 mg/kg recommendation (148 mg for this child) may provide suboptimal pain relief 2
- Do not exceed maximum daily dose: Four doses of 250 mg (1000 mg total) should not be exceeded in 24 hours 1
- Do not use as routine antipyretic: Consider paracetamol or ibuprofen first for simple fever; reserve mefenamic acid for pain or inflammatory conditions 1