What are the guidelines for pediatric therapeutic dosing?

Pediatric Therapeutic Dosing Guidelines

Pediatric drug dosing must be calculated based on weight (mg/kg) for most medications, with specific age-based adjustments for neonates and infants under 3 months due to immature organ function, and doses should never simply be scaled down from adult doses. 1, 2

General Dosing Principles by Age Group

Neonates and Infants <3 Months

• Maximum amoxicillin dose is 30 mg/kg/day divided every 12 hours due to incompletely developed renal function affecting drug elimination 3
• Glucuronidation pathways are immature in this age group, making certain medications unsafe (e.g., ambrisentan should be avoided in neonates and infants) 4
• For acetaminophen in infants under 3 months, use 15 mg/kg per dose if weight is less than 10 kg 5
• Oseltamivir dosing for term infants 0-8 months: 3 mg/kg/dose twice daily for 5 days 1

Infants 3-12 Months

• Oseltamivir for infants 9-11 months: 3.5 mg/kg/dose twice daily 1
• Most antibiotics can be dosed by weight, but therapeutic drug monitoring is recommended for narrow therapeutic index drugs 4, 2

Children >12 Months and <40 kg

• Weight-based dosing (mg/kg) is the standard approach for most medications 3, 2
• Amoxicillin for mild/moderate infections: 25 mg/kg/day divided every 12 hours or 20 mg/kg/day divided every 8 hours 3
• Amoxicillin for severe infections: 45 mg/kg/day divided every 12 hours or 40 mg/kg/day divided every 8 hours 3
• Acetaminophen: 10-15 mg/kg per dose every 4-6 hours, maximum 60 mg/kg/day 5
• Ibuprofen: 10 mg/kg per dose every 6-8 hours (not recommended for infants <6 months) 5

Children ≥40 kg

• Transition to adult dosing protocols for most medications 6, 3
• Body surface area (BSA) normalization becomes more appropriate after maturation is complete 2

Specific Drug Classes and Dosing

Antibiotics for Community-Acquired Pneumonia

For Streptococcus pneumoniae (fully susceptible):

• Parenteral: Penicillin G 200,000-250,000 units/kg/day divided every 4-6 hours, or ampicillin 150-200 mg/kg/day divided every 6 hours 4
• Oral: Amoxicillin 90 mg/kg/day divided twice daily (maximum 4 g/day) 4

For Methicillin-Resistant Staphylococcus aureus (MRSA):

• Parenteral: Vancomycin 40-60 mg/kg/day divided every 6-8 hours (or dosed to achieve AUC/MIC ratio >400) 4
• Oral: Clindamycin 30-40 mg/kg/day in 3-4 doses, or linezolid 30 mg/kg/day in 3 doses for children <12 years and 20 mg/kg/day in 2 doses for children ≥12 years 4

For Mycoplasma pneumoniae:

• Parenteral: Azithromycin 10 mg/kg on days 1-2, then transition to oral 4
• Oral: Azithromycin 10 mg/kg on day 1, then 5 mg/kg/day once daily on days 2-5 4

Tuberculosis Treatment

• Rifampin: 10-20 mg/kg daily (maximum 600 mg) 4
• Pyrazinamide: 15-30 mg/kg daily (maximum 2 g) 4
• Ethambutol: 15-20 mg/kg daily (maximum 1 g) 4

Pulmonary Hypertension Medications

• Epoprostenol: Starting dose 1-2 ng/kg/min IV, stable dose usually 50-80 ng/kg/min 4
• Treprostinil: Starting dose 2 ng/kg/min IV or SC, stable dose usually 50-80 ng/kg/min 4
• Sildenafil: Use in children <5 years is unstudied; avoid in neonates/infants 4

Emergency Medications

• Epinephrine for anaphylaxis: 0.01 mg/kg (0.01 mL/kg of 1:1000 solution) IM, maximum 0.3 mg per dose, repeat every 5 minutes as needed 1
• Glucose for hypoglycemia: 0.5-1.0 g/kg as D10W (2-4 mL/kg of D25W or 1-2 mL/kg of D50W) 4
• Lorazepam for seizures: 0.05-0.15 mg/kg IV/IM, maximum single dose 5 mg 4

Dose Rounding and Safety Considerations

Rounding Tolerance

• Narrow therapeutic index drugs should be rounded only to the nearest 0.1 mL or not rounded at all 1
• Standard medications can tolerate wider rounding percentages (up to 10% for some drugs like metoclopramide) after expert consensus 1
• Dose-dependent toxicity drugs should be rounded down to easily administered doses while respecting maximum dose guidelines 1

Common Pitfalls to Avoid

• Never exceed acetaminophen maximum of 60 mg/kg/day or 5 doses in 24 hours to prevent hepatotoxicity 5
• Do not use 875 mg amoxicillin dose in patients with GFR <30 mL/min 3
• Avoid ibuprofen in infants <6 months due to immature renal function 5
• Rectal acetaminophen has erratic absorption; oral syrup is preferred for consistent response 5

Treatment Duration and Monitoring

Standard Treatment Courses

• Most infections require minimum 48-72 hours of therapy beyond symptom resolution 3
• Streptococcus pyogenes infections require at least 10 days of treatment to prevent acute rheumatic fever 3
• Community-acquired pneumonia: 10-day courses are best studied, though shorter courses may be effective for mild disease 4
• CA-MRSA infections may require longer treatment than S. pneumoniae infections 4

Clinical Response Assessment

• Assess clinical and laboratory improvement within 48-72 hours of starting therapy 4, 6
• If no improvement or clinical deterioration occurs within 48-72 hours, perform further investigation 4, 6

Renal Impairment Adjustments

For amoxicillin in patients with severe renal impairment:

• GFR 10-30 mL/min: 500 mg or 250 mg every 12 hours 3
• GFR <10 mL/min: 500 mg or 250 mg every 24 hours 3
• Hemodialysis: 500 mg or 250 mg every 24 hours, with additional dose during and at end of dialysis 3