In a child aged ≥10 years and weighing >30 kg, what are the recommended doses, dosing intervals, maximum daily limits for mefenamic acid and paracetamol, and how should the two drugs be timed when given together?

Pediatric Dosing of Mefenamic Acid and Paracetamol for Children ≥10 Years and >30 kg

For a child aged ≥10 years weighing >30 kg, administer mefenamic acid 6 mg/kg per dose (maximum 500 mg) every 8 hours and paracetamol 10-15 mg/kg per dose (maximum 1000 mg) every 4-6 hours, with both medications given separately at staggered intervals to optimize fever control while avoiding simultaneous administration unless breakthrough symptoms require combination therapy.

Mefenamic Acid Dosing

• Dose: 6 mg/kg per dose, typically 200-500 mg depending on weight 1, 2
• Frequency: Every 8 hours 1
• Maximum daily dose: 1500 mg/day (three doses) 1
• Route: Oral, preferably with food to minimize gastrointestinal side effects 1

Clinical Evidence for Mefenamic Acid

• Mefenamic acid at 6 mg/kg demonstrates superior antipyretic efficacy compared to standard-dose paracetamol (15 mg/kg), with faster temperature reduction and longer duration of action (8.82±3.83 hours vs 5.07±2.66 hours) 1
• The optimal antipyretic effect occurs at 4 mg/kg, showing 2.5 times the efficacy of paracetamol at equivalent doses 2
• For children >30 kg, a practical dose is 250-500 mg per dose, not exceeding 500 mg per dose 1

Paracetamol Dosing

• Dose: 10-15 mg/kg per dose 3, 4
• Frequency: Every 4-6 hours 3, 4
• Maximum daily dose: 60 mg/kg/day, not exceeding 4000 mg/day in adolescents 3, 4
• Route: Oral, can be given without regard to meals though food may improve tolerability 3

Weight-Based Paracetamol Dosing for Children >30 kg

• 30-40 kg: 300-600 mg per dose (10-15 mg/kg) 3
• >40 kg: 500-750 mg per dose, maximum 1000 mg per dose 3
• Maximum 4 doses in 24 hours 4

Timing Strategy When Using Both Medications

Staggered administration is recommended to maintain continuous fever control:

• Administer paracetamol first (e.g., at time 0)
• Give mefenamic acid 3-4 hours later 1
• Continue paracetamol every 4-6 hours
• Continue mefenamic acid every 8 hours
• This creates overlapping coverage without simultaneous peak drug levels

Rationale for Staggered Dosing

• High-dose paracetamol (20 mg/kg) and mefenamic acid (6 mg/kg) show equivalent antipyretic effects, with temperature reduction of 0.46°C vs 0.45°C at 60 minutes respectively 1
• Mefenamic acid provides longer duration of action (8.82 hours) compared to standard paracetamol (5.07 hours), allowing for less frequent dosing 1
• Staggered administration prevents medication errors and reduces risk of inadvertent overdose 3

Critical Safety Considerations

Paracetamol-Specific Warnings

• Never exceed 60 mg/kg/day or 4000 mg/day - chronic overdosing above 140 mg/kg/day for several days carries serious hepatotoxicity risk 4
• Counsel caregivers to avoid all other paracetamol-containing products, including over-the-counter cold remedies, as inadvertent overdose is common 3
• Single ingestions exceeding 150 mg/kg are potentially hepatotoxic and require immediate medical evaluation 4

Mefenamic Acid-Specific Warnings

• Reserve mefenamic acid for pain or when paracetamol alone is insufficient, as NSAIDs carry greater safety concerns than paracetamol 1
• Monitor for gastrointestinal side effects; administer with food 1
• Avoid in children with renal impairment, active peptic ulcer disease, or bleeding disorders 1
• Negligible adverse effects were reported at 6 mg/kg dosing in clinical trials 1

Practical Algorithm for Medication Selection

Step 1: Start with paracetamol 10-15 mg/kg every 4-6 hours for initial fever management 3, 4

Step 2: If fever persists or recurs within 4-5 hours, consider adding mefenamic acid 6 mg/kg at the 3-4 hour mark after paracetamol 1

Step 3: Continue both medications on staggered schedule if needed, with paracetamol every 4-6 hours and mefenamic acid every 8 hours 1

Step 4: Once fever controlled for 24 hours, discontinue mefenamic acid first and continue paracetamol as needed 1

When to Avoid Combination Therapy

• Mild fever (<38.5°C) without significant discomfort - use paracetamol alone 1
• Adequate response to paracetamol monotherapy - no need to add NSAID 1
• Presence of contraindications to NSAIDs (renal disease, bleeding disorders, gastritis) 1