Gentamicin

C. diff Risk

Low

Oral Bioavailability

NA

Approximate Cost

Dosing

Use Adjusted Body Weight for obese patients (BMI ≥30 kg/m2) Once Daily Dosing 5-7 mg/kg IV every 24 hr Multiple Daily Dosing 1.5-2 mg/kg IV every 8 hr Synergy(for gram positive infections) 1 mg/kg IV every 8 hr Recommend dosing per Pharmacy

General Information

Common Usage

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

Empiric therapy for pyelonephritis.

Used synergistically in enterococcal endocarditis.

Drug Monitoring

Lab

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

  • Once daily dosing: Target trough <1mcg/mL

  • Multiple daily dosing: Peak monitoring poorly supported by literature, but target peak 4-10 mcg/mL; trough 1-2 mcg/mL (Only draw levels if using > 4 days)

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

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

Clinical

  • Baseline and periodic hearing and vestibular function testing (particularly in those receiving prolonged therapy)

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

Formal audiology assessment if planning to use aminoglycoside for > 7 days 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

CSF penetration: Poor

Biliary penetration: Moderate

Lung penetration: Therapeutic

Urine penetration: Therapeutic