Pediatric Dosing Extrapolation Error
Issue: Agent Extrapolates Adult Weight-Based or Fixed Dosing Formulas to Pediatric Patients, Producing Unsafe Doses
Frequency: Common
Symptoms
- Pediatric dose calculated by naively scaling adult dose by body weight ratio, ignoring nonlinear pediatric pharmacokinetics
- Neonatal and infant dosing (which often requires different mg/kg/day schedules than older children) treated identically to general “pediatric” dosing
- Maximum single-dose or daily-dose caps from adult labeling applied incorrectly to children, or pediatric-specific caps missed entirely
- Liquid formulation concentration errors not caught when converting a weight-based dose to a volume to administer
Root Cause Pediatric pharmacokinetics differ nonlinearly from adults due to differences in body composition, organ maturation (renal/hepatic clearance), and developmental stage — a simple linear weight-based scaling of adult dosing is frequently incorrect and can be dangerously high or low depending on the drug. Many models default to generic “mg/kg” scaling learned from training data without applying drug-specific, age-band-specific pediatric dosing references (e.g., neonatal vs. infant vs. adolescent bands), and without flagging the formulation/concentration conversion step where calculation errors are common.
Example
Scenario: Pediatric agent dosing a renally-cleared antibiotic for a 6-month-old infant
Naive approach: Scale adult dose by weight ratio (e.g., 10kg/70kg * adult dose)
Correct approach: Use infant-specific mg/kg/dose and dosing-interval schedule from a pediatric reference (interval often differs from adult, not just dose magnitude)
Discrepancy: Linear adult-scaling under- or over-doses by a clinically significant margin depending on drug-specific pediatric PK
Impact: Subtherapeutic dosing risks treatment failure; supratherapeutic dosing risks toxicity in an immature renal/hepatic system
Key Statistics
- Pediatric medication dosing errors, particularly in neonates and infants, are reported at substantially higher rates than adult dosing errors in hospital medication-safety studies
- Weight-based linear extrapolation from adult dosing is a recognized root cause category in pediatric adverse drug event reviews
- Formulation/concentration conversion errors (mg-to-mL calculations) account for a notable share of pediatric dosing incidents independent of the dose-calculation itself
Mitigation Strategies
- Pediatric-Specific Dosing References: Always query a dedicated pediatric dosing reference (age-band-specific mg/kg/dose and interval), never linearly extrapolate from adult dosing
- Age-Band Stratification: Explicitly branch dosing logic by neonate/infant/child/adolescent age bands rather than a single “pediatric” bucket
- Independent Concentration-Conversion Check: Add a separate verification step for mg-to-mL/volume conversion, flagged for pharmacist double-check
- Maximum Dose Cap Enforcement: Encode pediatric-specific (not adult) maximum single and daily dose caps per drug
Metrics
- % of pediatric dose calculations using age-band-specific reference vs. linear adult extrapolation
- Dosing error rate stratified by age band (neonate/infant/child/adolescent)
- Concentration-conversion error rate
Alerts
- Pediatric dose calculated via linear adult-weight scaling without age-band reference → P1
- Calculated dose exceeds pediatric-specific maximum for age band → P1