Amoxicillin Dosing for a 30-lb Infant
For a 30-lb (13.6 kg) infant receiving amoxicillin 250 mg/5 mL suspension every 12 hours, administer 5 mL (125 mg) per dose for mild to moderate infections, or 9 mL (225 mg) per dose for severe infections. 1
Weight-Based Dosing Calculation
A 30-lb infant weighs approximately 13.6 kg. According to FDA labeling for amoxicillin, the recommended dosing for pediatric patients aged 3 months and older depends on infection severity: 1
Mild to Moderate Infections
- Standard dose: 25 mg/kg/day divided every 12 hours 1
- Calculation: 13.6 kg × 25 mg/kg/day = 340 mg/day
- Per dose (every 12 hours): 170 mg/dose
- Volume: Approximately 5 mL of 250 mg/5 mL suspension (delivers 125 mg)
Severe Infections or Resistant Organisms
- High dose: 45 mg/kg/day divided every 12 hours 1
- Calculation: 13.6 kg × 45 mg/kg/day = 612 mg/day
- Per dose (every 12 hours): 306 mg/dose
- Volume: Approximately 6 mL of 250 mg/5 mL suspension (delivers 150 mg) for moderate-severe, or up to 9 mL (225 mg) for severe infections
Clinical Context for Dosing Selection
The choice between standard and high-dose regimens depends on the suspected pathogen and infection severity:
Use standard dosing (25 mg/kg/day) for uncomplicated infections such as mild otitis media, pharyngitis, or simple urinary tract infections 1
Use high-dose regimens (45 mg/kg/day) for severe infections, lower respiratory tract infections, or when penicillin-resistant Streptococcus pneumoniae is suspected 1, 2
High-dose amoxicillin formulations were specifically developed to provide better coverage against penicillin-intermediate and penicillin-resistant S. pneumoniae strains 2
Important Administration Guidelines
Key points for safe and effective administration:
Administer at the start of a meal to minimize gastrointestinal intolerance 1
Shake the oral suspension well before each use 1
Continue treatment for a minimum of 48-72 hours beyond symptom resolution or evidence of bacterial eradication 1
For Streptococcus pyogenes infections (strep throat), treat for at least 10 days to prevent acute rheumatic fever 1
Refrigeration of reconstituted suspension is preferable but not required; discard any unused portion after 14 days 1
Common Pitfalls to Avoid
Do not underdose: Using the 250 mg/5 mL concentration, ensure accurate measurement with an oral syringe rather than household spoons
Avoid premature discontinuation: Complete the full course even if symptoms improve, particularly for streptococcal infections 1
Consider resistance patterns: In areas with high rates of penicillin-resistant S. pneumoniae, or for treatment failures, high-dose amoxicillin (45 mg/kg/day) or amoxicillin-clavulanate may be more appropriate 2