Gentamicin

Restricted
Restricted

C. diff Risk

Low

Oral Bioavailability

None

Approximate Cost

$3 + monitoring

General Information

Common Usage

Empiric (in combination) or targeted therapy for suspected or confirmed resistant gram negative infections.

Empiric therapy for pyelonephritis.

Used synergistically in enterococcal or streptococcal endocarditis.

Drug Monitoring

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

Once daily dosing: Hartford nomogram.

Renal dysfunction and extended interval dosing: Peak monitoring poorly supported by literature, but target peak 8-10mcg/mL; trough 1-2mcg/mL

Trough is 30 minutes before next dose. Peak is 30 minutes after 30 minute infusion

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

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

Increased nephrotoxicity

  •  Amphotericin

  •  Vancomycin

  •  Cyclosporin

  •  NSAIDs

  •  Contrast

Increased ototoxicity

  •  Loop diuretics (e.g. furosemide)

Non-depolarizing muscle relaxants may be potentiated

Additional Information

Restricted to Infectious Diseases, OBGYN (FBC) and NICU

Formal audiology assessment if planning to use aminoglycoside for >7d or if symptoms develop.

Inform patient of risk of ototoxicity and to report any symptoms.

Pharmacology

Antimicrobial class: Aminoglycoside

Pregnancy category: D

Average serum half life: 2 hours

Biliary penetration: Moderate

CSF penetration: Poor

Lung penetration: Therapeutic

Urine penetration: Therapeutic