Spectrum: Local Antimicrobial Stewardship, for Markham Stouffville Hospital

Gentamicin Synergy

C. diff Risk

Low

Oral Bioavailability

NA

Approximate Cost

Dosing

Adult

General Information

Common Usage

Common Usage

Used synergistically in enterococcal endocarditis

Drug Monitoring

Drug Monitoring

Monitor creatinine at least 3 times/week. Discontinue if any signs of ototoxicity.

Synergy dosing:

  •  Target trough: less than 1mg/L

  •  Target peak: 3-4mg/L

NB: Trough level is 0-60min before a dose (usually pre-4th), and peak is 30-60min after dose infused (usually post-3rd).

In critically ill patients, check peak level after the 1st dose as volume of distribution and renal function may change rapidly.

Adverse Effects

Adverse Effects

Nephrotoxicity (non-oliguric)

  •  Avoid concomitant nephrotoxins

  •  Less common with once daily dosing

  •  Greater toxicity with longer duration and supratherapeutic trough levels

Vestibulocochlear toxicity

  • Irreversible

  • Require audiology testing if prolonged use

Can exacerbate neuromuscular blockade

  •  Contraindicated in patients with myasthenia gravis

Major Interactions

Major Interactions

Increased nephrotoxicity

  •  Amphotericin

  •  Vancomycin

  •  Cyclosporin

  •  NSAIDs

  •  Contrast

Increased ototoxicity

  •  Loop diuretics (e.g. furosemide)

Non-depolarizing muscle relaxants may be potentiated

Pharmacology

Pharmacology

Antimicrobial class: Aminoglycoside

Pregnancy category: D

Average serum half life: 2 hours

Biliary penetration: Moderate

CSF penetration: Poor