Paediatric Dosage Adjustment Guidelines

Safe prescribing in children requires careful adjustment of medication based on **weight, age, organ maturity, renal/hepatic function, clinical severity, and drug toxicity**. This guide provides simple ED-friendly rules to ensure safe dosing.

General Principles

Always use weight in kilograms. Never estimate unless absolutely necessary.
Drug doses should be mg/kg or micrograms/kg.
Infants metabolise drugs differently. Neonates especially have immature organs.
Never exceed the recommended adult dose.
Re-check calculations twice for high-risk drugs (opiates, sedatives, electrolytes, adrenaline).

Broselow Tape Rule: If weight is unknown: weight (kg) ≈ (age in years + 4) × 2.

Renal Function & Dose Adjustment

Children do not use Cockcroft-Gault. Instead, use:

Schwartz Formula (Paediatrics):
eGFR (mL/min/1.73m²) = 0.413 × height (cm) / serum creatinine (mg/dL)

Renally cleared drugs requiring adjustment in children include:

Aminoglycosides (gentamicin, amikacin)
Vancomycin
Cefepime, ceftriaxone (severe impairment only)
Oseltamivir
Apixaban/rivaroxaban (age dependent)

HIGH RISK: Gentamicin dose errors are a common cause of paediatric adverse events. Always confirm dose & frequency with a calculator/pharmacist.

Hepatic Impairment in Children

The **Child-Pugh score is NOT used for paediatrics**. Instead, dosing is based on clinical staging and specialist guidance.

Avoid or reduce paracetamol in moderate–severe hepatic disease.
Avoid benzodiazepines if hepatic encephalopathy suspected.
Consider dose reduction for morphine, codeine, and anticonvulsants.

General rule: If the child has jaundice, coagulopathy, ascites, or hepatomegaly, assume impaired metabolism → reduce dose and give longer intervals.

Practical ED Dosing Tips

Concentrations matter — check the vial strength before calculating.
Round volumes sensibly, not doses (e.g., to nearest 0.1–0.2 mL for small volumes).
Use oral syringes for liquid meds; never use teaspoons.
Document mg/kg, total mg, and final mL for clarity.
Monitor high-risk drugs (opiates, insulin, electrolytes, sedatives).

RED FLAG: Any paediatric drug dose > adult dose is almost always wrong.

When to Ask for Help

Always consult a paediatric pharmacist, paediatrician, or senior ED doctor when prescribing:

Infant < 3 months
Renal or liver disease
IV sedation or opiates
Electrolyte replacements
Anticonvulsants
Toxic ingestion or overdose