Ampicillin Pediatric Dose — Antimicrobial Dosing Guide
Ampicillin is a broad-spectrum aminopenicillin antibiotic that exerts bactericidal activity by inhibiting bacterial cell wall synthesis. It is commonly used in pediatric practice for the empiric and definitive treatment of serious bacterial infections, including sepsis, meningitis, pneumonia, and urinary tract infections caused by susceptible organisms. Ampicillin provides coverage against many gram-positive cocci, select gram-negative bacilli, and Listeria monocytogenes.
Pediatric Dosing
- Dose: 50–100 mg/kg/dose IV every 6 hours
- Adult dose: 2 g IV every 6 hours
- Maximum daily dose: 14 g/day
The dose selected within the 50–100 mg/kg/dose range depends on the severity and site of infection. Higher doses (100 mg/kg/dose) are typically used for central nervous system infections such as bacterial meningitis, while lower doses may be appropriate for less severe infections. Consult institutional protocol for neonatal dosing intervals, which differ from those used in older children.
Worked example: For a 20 kg child receiving 75 mg/kg/dose: 20 × 75 mg/kg = 1,500 mg (1.5 g) per dose, administered IV every 6 hours. Total daily dose would be 6,000 mg (6 g/day), well within the 14 g/day maximum.
Indications and Clinical Context
Ampicillin is a foundational antimicrobial agent in pediatric infectious disease management. It is used for the empiric treatment of neonatal sepsis and meningitis (typically in combination with gentamicin), community-acquired pneumonia, urinary tract infections, and intra-abdominal infections (in combination regimens). Coverage includes Streptococcus pneumoniae, Group B Streptococcus, Listeria monocytogenes, and susceptible Enterococcus and Haemophilus influenzae strains.
In the context of neonatal and pediatric resuscitation and critical illness, ampicillin is frequently included in empiric sepsis bundles per institutional and PALS-aligned protocols. Susceptibility patterns and local antibiogram data should guide definitive therapy, as ampicillin resistance among gram-negative organisms is common.
Administration and Monitoring
Ampicillin is administered by the intravenous (IV) route for serious infections as described in this dosing reference. It may be given as a slow IV push over 10–15 minutes or as a short infusion per institutional practice. Ensure patency of IV access prior to administration; extravasation may cause tissue irritation.
- Route: IV (as specified); consult institutional protocol for IM use in non-critical settings
- Max daily dose: 14 g/day
- Monitoring: Renal function (dose adjustment may be required in renal impairment), signs of hypersensitivity or anaphylaxis, hepatic transaminases with prolonged use
- Adverse effects: Hypersensitivity reactions (rash, urticaria, anaphylaxis), diarrhea, elevated hepatic enzymes, and Clostridioides difficile-associated diarrhea with prolonged therapy
- Contraindications: Known allergy to penicillins or cephalosporins (cross-reactivity); use with caution in patients with a history of significant beta-lactam hypersensitivity
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.