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Pediatric Dosage Calculation Methods

Jul 1, 2025

Overview

This lecture reviews how to use Fried's Rule, Young's Rule, and Clark's Rule to calculate pediatric medication dosages, using a sample problem.

Fried's Rule

  • Formula: Pediatric dose = (Age in months / 150) × Adult dose.
  • Given: Age = 24 months, Adult dose = 500 mg.
  • Calculation: (24 / 150) × 500 mg = 80 mg.

Young's Rule

  • Formula: Pediatric dose = [Age in years / (Age in years + 12)] × Adult dose.
  • Convert 24 months to 2 years.
  • Calculation: [2 / (2 + 12)] × 500 mg = 71 mg.

Clark's Rule

  • Formula: Pediatric dose = (Weight in pounds / 150) × Adult dose.
  • Convert 13 kg to pounds: 13 × 2.2 = 28.6 lb.
  • Calculation: (28.6 / 150) × 500 mg = 95 mg.

Comparing the Results

  • Fried's Rule result: 80 mg.
  • Young's Rule result: 71 mg.
  • Clark's Rule result: 95 mg.
  • Each rule uses different child specifics (age in months, age in years, weight in pounds) for dosage calculation.

Key Terms & Definitions

  • Fried's Rule — pediatric dose calculation for infants using age in months.
  • Young's Rule — pediatric dose calculation for children using age in years.
  • Clark's Rule — pediatric dose calculation based on child's weight in pounds.
  • Adult Dose — standard dosage prescribed for adults.

Action Items / Next Steps

  • Practice more pediatric dosage calculations using all three rules for different scenarios to build confidence.