Pediatric Dosing of Penicillin V (Pen V)
For children 12 years and older, the standard dose of Penicillin V is 125-250 mg every 6-8 hours for mild to moderate streptococcal infections, or 250-500 mg every 6 hours for pneumococcal infections; for children under 12 years and under 60 lbs (27 kg), use 1 gram (1000 mg) as a single dose for endocarditis prophylaxis, or 500 mg 6 hours later. 1
Age-Based Dosing Framework
Children ≥12 Years and Adults
The FDA-approved dosing varies by indication 1:
- Streptococcal infections (mild to moderate): 125-250 mg (200,000-400,000 units) every 6-8 hours for 10 days 1
- Pneumococcal respiratory infections: 250-500 mg (400,000-800,000 units) every 6 hours until afebrile for at least 2 days 1
- Staphylococcal skin/soft tissue infections: 250-500 mg every 6-8 hours 1
- Vincent's infection: 250-500 mg every 6-8 hours 1
- Rheumatic fever prophylaxis: 125-250 mg twice daily on a continuing basis 1
Children Under 60 lbs (27 kg)
For bacterial endocarditis prophylaxis specifically: 1 gram (1000 mg) given 1 hour before the procedure, then 500 mg 6 hours later 1
Critical Dosing Considerations
Weight-Based Calculation Approach
When precise pediatric dosing is not specified in the FDA label, a practical weight-based approach can be applied 2:
- Children ≤30 kg: Calculate (weight × 2)% of the adult dose 2
- Children >30 kg: Calculate (weight + 30)% of the adult dose 2
This method follows body surface area curves more accurately than simple mg/kg dosing and reduces prescription errors 2.
Important Clinical Caveats
Always document the child's current weight in kilograms on the prescription to enable proper dose verification by the dispensing pharmacist 3. Without this information, pharmacists cannot adequately verify weight-based dosing accuracy in pediatric patients 3.
For children under 2 years of age, dosing should be individualized based on developmental pharmacokinetics, as absorption, distribution, metabolism, and excretion differ significantly from older children 4. Penicillin V is primarily renally excreted, and renal function maturation is incomplete in this age group 4.
Common Pitfalls to Avoid
- Do not assume standard adult dosing is appropriate for children under 12 years without weight-based adjustment 5
- Do not use outdated age-based dosing rules (like Clark's rule or Young's rule) as they are less accurate than weight-based or BSA-based calculations 2
- Ensure proper reconstitution of oral solution: add water in two portions, shake well, and store refrigerated for maximum 14 days 1
- Always shake the oral solution well before each use 1