Gentamicin Pediatric Dose — Antimicrobial Dosing Guide
Gentamicin is an aminoglycoside antibiotic that exerts bactericidal activity by irreversibly binding the 30S ribosomal subunit, inhibiting bacterial protein synthesis. It is active against a broad range of gram-negative aerobic organisms and is commonly used in pediatrics for serious infections including sepsis, urinary tract infections, and in combination regimens for gram-positive coverage. Therapeutic drug monitoring is essential due to its narrow therapeutic index and risk of nephrotoxicity and ototoxicity.
Pediatric Dosing
| Patient Population | Dose | Frequency |
|---|---|---|
| Term Infants <1 month | 2.5 mg/kg/dose IV | Every 8 hours |
| Children >1 month | 5–7.5 mg/kg/day IV | Every 24 hours |
| Cystic Fibrosis (CF) | 10 mg/kg/dose IV | Every 24 hours |
Maximum dose: 500 mg/day, except in cystic fibrosis patients, for whom higher exposures may be required per the CF-specific dosing above.
Worked example — children >1 month: For a 20 kg child at 5 mg/kg/day: 20 × 5 mg/kg = 100 mg IV once daily. At 7.5 mg/kg/day the same child would receive 20 × 7.5 = 150 mg IV once daily. Neonatal example: For a 3.5 kg term neonate: 3.5 × 2.5 mg/kg = 8.75 mg IV every 8 hours.
Indications and Clinical Context
Gentamicin is a first-line aminoglycoside for serious gram-negative infections in pediatric patients, including bacteremia, pyelonephritis, neonatal sepsis, and intra-abdominal infections. In neonates under one month of age, the reduced glomerular filtration rate necessitates an every-8-hour interval at the lower 2.5 mg/kg/dose to balance efficacy with renal safety. For children older than one month, extended-interval (once-daily) dosing at 5–7.5 mg/kg/day leverages the concentration-dependent killing and post-antibiotic effect of aminoglycosides while minimizing toxicity risk.
In patients with cystic fibrosis, altered pharmacokinetics — including increased volume of distribution and enhanced renal clearance — necessitate higher dosing at 10 mg/kg/dose every 24 hours to achieve adequate serum peak concentrations. Gentamicin is often used synergistically with beta-lactam antibiotics in empiric regimens for high-acuity pediatric infections consistent with current PALS and Infectious Diseases Society guidelines.
Administration and Monitoring
Gentamicin is administered intravenously, typically as an infusion over 30 minutes. Therapeutic drug monitoring (TDM) is strongly recommended: for extended-interval dosing, a trough level drawn just prior to the next dose (or a random level timed per institutional nomogram) guides dosing adjustments. For every-8-hour neonatal dosing, both peak (drawn 30 minutes after infusion end) and trough (drawn just prior to next dose) levels should be obtained. Target peaks and troughs vary by indication and institutional protocol — consult institutional guidelines for specific targets.
- Nephrotoxicity: Monitor serum creatinine and urine output; avoid concurrent nephrotoxic agents where possible.
- Ototoxicity: Auditory and vestibular toxicity may be irreversible; minimize unnecessary prolonged courses.
- Max dose: Do not exceed 500 mg/day except in cystic fibrosis patients.
- Renal impairment: Dose interval adjustment is required; consult institutional protocol for individualized guidance.
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.