Please check your internet connection and try again.
# IV Gentamicin
## Overview
Gentamicin is an aminoglycoside antibiotic that acts via irreversible binding to the 30S ribosomal subunit, inhibiting bacterial protein synthesis. It provides concentration-dependent bactericidal activity, primarily against aerobic Gram-negative bacilli.
## Primary Indications
* Serious Gram-negative infections (e.g., *Pseudomonas aeruginosa*, *Enterobacteriaceae*).
* Synergistic treatment for Gram-positive endocarditis (e.g., *Enterococcus*, *Staphylococcus aureus*).
* Empiric treatment for suspected sepsis (often in combination with beta-lactams).
## Adult Dosing
* **Traditional/Multiple Daily Dosing:** 3–5 mg/kg/day divided every 8 hours.
* **Extended Interval Dosing (EID):** 5–7 mg/kg administered every 24–48 hours based on renal function (often guided by the Hartford Nomogram).
* **Synergy Dosing (Endocarditis):** 1 mg/kg every 8 hours (adjusted for renal function).
* **Maximum:** Do not exceed 7 mg/kg/dose for EID unless directed by specific local protocols due to toxicity risks.
## Pediatric Dosing
* **Neonates (Post-menstrual age dependent):** 3–5 mg/kg/dose. Frequency is dictated by gestational age and postnatal age (e.g., every 24, 36, or 48 hours).
* **Pediatrics/Infants (>1 mo):** 2.5 mg/kg IV every 8 hours (traditional) or 7.5 mg/kg/dose once daily (EID, institutional protocol dependent).
## Dose Adjustments
* **Renal Impairment:** Mandatory dose interval extension or dose reduction based on CrCl or serum creatinine. Consult local nomograms for specific CrCl breakpoints.
* **Obesity:** Use Adjusted Body Weight (AdjBW) for calculating initial doses to avoid over-dosing due to poor tissue penetration in adipose tissue.
## Contraindications
* Hypersensitivity to aminoglycosides.
* History of severe myasthenia gravis (can exacerbate muscle weakness).
## Adverse Effects
* **Nephrotoxicity:** Usually reversible; associated with trough accumulation.
* **Ototoxicity:** Irreversible auditory (vestibular/cochlear) damage.
* **Neuromuscular Blockade:** Rare but severe, especially in patients receiving anesthetics or neuromuscular blockers.
## Key Drug Interactions
* **Nephrotoxic agents:** Increased risk of renal failure with concurrent cisplatin, amphotericin B, vancomycin, NSAIDs, or IV contrast.
* **Loop diurectics:** May potentiate ototoxicity.
* **Neuromuscular blocking agents:** Potential to prolong paralysis.
## Monitoring
* **Renal function:** Daily serum creatinine and BUN.
* **Therapeutic Drug Monitoring (TDM):**
* **Traditional:** Peak (30 min post-infusion) and Trough (pre-dose).
* **EID:** Random level performed 6–14 hours post-infusion (plotted on site-specific nomogram).
* **Clinical:** Monitor for tinnitus, vertigo, or hearing loss.
## Clinical Pearls
* Gentamicin does not penetrate deeply into abscesses or CNS tissue; should not be used as monotherapy for these indications.
* Post-Antibiotic Effect (PAE) is significant, which supports the efficacy of once-daily dosing.
* Always ensure adequate hydration to mitigate nephrotoxicity.
* **Important:** Dosing protocols for aminoglycosides are highly institutional-specific. Always correlate dosing with your facility’s specific pharmacokinetic guidelines.
***
**Disclaimer:** This information is for educational purposes for healthcare professionals. Clinical practice guidelines and local formulary protocols take precedence. Always verify current prescribing information, patient-specific renal function, and weight-based calculations before administration.
