What is the recommended dose of ampicillin (Ampicillin) intravenous (IV) for pediatric patients?

Ampicillin IV Pediatric Dosing

For most pediatric infections, ampicillin IV should be dosed at 100-200 mg/kg/day divided every 6 hours, with neonatal dosing adjusted based on gestational and postnatal age. 1, 2

Standard Pediatric Dosing (Infants and Children)

• The recommended dose is 100-200 mg/kg/day divided every 6 hours for most infections in infants and children beyond the neonatal period 1
• This dosing range is endorsed by both the Infectious Diseases Society of America and FDA labeling 1, 2

Neonatal Dosing (≤28 Days Postnatal Age)

Neonatal dosing must be stratified by both gestational age and postnatal age to account for immature renal function:

For Neonates ≤7 Days Postnatal Age:

• Weight ≤2000 g: 50 mg/kg/day divided every 12 hours 1
• Weight >2000 g: 75 mg/kg/day divided every 8 hours 1

For Neonates >7 Days Postnatal Age:

• Weight <1200 g: 50 mg/kg/day divided every 12 hours 1
• Weight 1200-2000 g: 75 mg/kg/day divided every 8 hours 1
• Weight >2000 g: 100 mg/kg/day divided every 6 hours 1

Indication-Specific Dosing

Bacterial Meningitis:

• Adults and children: 150-200 mg/kg/day divided every 3-4 hours 2
• For neonates with meningitis, use gestational age-based dosing: gestational age ≤34 weeks requires 100 mg/kg/day every 12 hours if postnatal age ≤7 days, or 150 mg/kg/day every 12 hours if postnatal age 8-28 days 2
• For neonates >34 weeks gestational age: 150 mg/kg/day divided every 8 hours 2

Septicemia:

• 150-200 mg/kg/day, starting with IV administration for at least 3 days, then continuing every 3-4 hours 2
• Neonatal septicemia follows the same gestational/postnatal age-based dosing as meningitis 2

Severe Infections (Penicillin-Resistant Streptococcus pneumoniae):

• 300-400 mg/kg/day divided every 6 hours by parenteral route 1
• This higher dosing is specifically for pneumonia caused by resistant organisms 1

Group A Streptococcal Infections:

• 200 mg/kg/day divided every 6 hours IV 1
• Treatment must continue for a minimum of 10 days to prevent acute rheumatic fever or acute glomerulonephritis 2

Administration Guidelines

IV Administration:

• For direct IV push: Dissolve and administer slowly over 3-5 minutes for 250-500 mg vials 2
• For 1-2 gram doses: Administer over at least 10-15 minutes 2
• CAUTION: More rapid administration may result in convulsive seizures 2

Duration of Therapy:

• Continue treatment for a minimum of 48-72 hours beyond symptom resolution or bacterial eradication 2
• Clinical improvement should be expected within 48-72 hours of starting therapy; if no improvement occurs, consider alternative diagnoses or resistant organisms 1

Important Clinical Considerations

• Bacteriostatic Water for Injection must NOT be used as a diluent in newborns 2
• Reconstituted solutions lose potency after 1 hour at room temperature; use only freshly prepared solutions 2
• For community-acquired pneumonia in fully immunized children with minimal local penicillin resistance, ampicillin is the first-line treatment 1
• The combination of ampicillin with sulbactam (2:1 ratio) has demonstrated 96-98% cure rates in pediatric infections when dosed at 200 mg ampicillin + 100 mg sulbactam per kg/day 3, 4