Please check your internet connection and try again.
# IV Gentamicin
## Overview
Gentamicin is an aminoglycoside antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. It exhibits concentration-dependent bactericidal activity and a significant post-antibiotic effect.
## Primary Indications
Serious infections caused by susceptible Gram-negative bacilli (e.g., *Pseudomonas aeruginosa*, *Enterobacteriaceae*), including sepsis, complicated UTIs, pneumonia, and intra-abdominal infections. Often used in synergy with beta-lactams/glycopeptides for endocarditis.
## Adult Dosing
* **Traditional (Multiple Daily Dose):** 3–5 mg/kg/day divided every 8 hours.
* **Extended Interval (Once-Daily):** 5–7 mg/kg every 24 hours. (Highly dependent on local protocols and nomograms like Hartford or Sawchuk-Zaske).
* **Synergy for Endocarditis:** 1 mg/kg every 8 hours (target peaks 3–5 mcg/mL; troughs <1 mcg/mL).
## Pediatric Dosing
Dosing is highly age-dependent; strict adherence to institution-specific weight-based protocols is mandatory.
* **Neonatal (Term):** 4–5 mg/kg/dose. Frequency based on gestational age: Q24h to Q48h.
* **Infants/Children:** 7.5 mg/kg/day divided every 8 hours (or 5–7 mg/kg once daily depending on site/severity).
## Dose Adjustments
* **Renal Impairment:** Mandatory dose interval extension or dose reduction based on CrCl. Use Cockcroft-Gault for adults. Avoid or monitor very closely in ESRD.
* **Obesity:** Use Adjunct Body Weight (ABW) or Ideal Body Weight (IBW) based on local policy to prevent accumulation.
## Contraindications
* Hypersensitivity to gentamicin or other aminoglycosides.
* Use caution in myasthenia gravis or conditions involving neuromuscular blockade.
## Adverse Effects
* **Nephrotoxicity:** Usually reversible; associated with high troughs.
* **Ototoxicity:** Irreversible; vestibular (vertigo/ataxia) or cochlear (hearing loss/tinnitus).
* **Neuromuscular Blockade:** Potential for respiratory paralysis, especially if given rapidly or with paralytics.
## Key Drug Interactions
* **Nephrotoxic Agents:** Increased risk with vancomycin, amphotericin B, cisplatin, cyclosporine, and NSAIDs.
* **Neuromuscular Blockers:** Synergistic effect; monitor for prolonged respiratory depression.
* **Loop Diuretics:** Increased risk of ototoxicity (e.g., furosemide).
## Monitoring
* **Serum Levels:** Mandatory for extended courses (>3 days).
* *Traditional:* Measure peak (30 min post-infusion) and trough (immediately pre-dose).
* *Extended Interval:* Random level 6–14 hours post-infusion (plot on nomogram).
* **Renal Function:** Monitor SCr, BUN, and urine output daily. Target trough levels <1–2 mcg/mL (or <1 mcg/mL for synergy).
## Clinical Pearls
* Gentamicin has poor CNS penetration; it is not for meningitis.
* Always infuse over 30–60 minutes to prevent peak-related toxicity and neuromuscular block.
* "Trough-only" monitoring is the modern standard for extended-interval dosing to minimize toxicity.
***
**Disclaimer:** This information is for educational purposes and reflects general clinical practice. Gentamicin dosing must be verified against current institutional policies, patient-specific renal function, and updated manufacturer prescribing information before administration.
