C. diff Risk


Oral Bioavailability


Approximate Cost



Height Males Females
150.0 cm 50.0 kg 45.5 kg
152.5 cm 52.3 kg 47.8 kg
155.0 cm 54.6 kg 50.1 kg
157.5 cm 56.9 kg 52.4 kg
160.0 cm 59.2 kg 54.7 kg
162.5 cm 61.5 kg 57.0 kg
165.0 cm 63.8 kg 59.3 kg
167.5 cm 66.1 kg 61.6 kg
170.0 cm 68.4 kg 63.9 kg
172.5 cm 70.7 kg 66.2 kg
175.0 cm 73.0 kg 68.5 kg
177.5 cm 75.3 kg 70.8 kg
180.0 cm 77.6 kg 73.1 kg
182.5 cm 79.9 kg 75.4 kg
185.0 cm 82.2 kg 77.7 kg
187.5 cm 84.5 kg 80.0 kg
190.0 cm 86.8 kg 82.3 kg

General Information

Unacceptable Uses

Monotherapy of gram positive or anaerobic infections

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

Serum creatinine whenever initiating any aminoglycoside.

Creatinine and trough level should be monitored AT LEAST twice weekly; more often if unstable renal function or addition of nephrotoxic medications.

Order appropriate trough level for dosage regimen being used

Once Daily/Extended Interval Dosing

  • Order 6 hour pre-dose level

  • Target level: less than 1 mg/L

Multiple Daily Dosing

  • Order gentamicin trough level (0-60 min before a dose)

  • Desired result: less than 2 mg/L

Gentamicin Peaks
Are not used in once daily/extended interval regimens

For multiple daily dosing regimens, peaks not commonly measured but if required are collected 30-60 min after dose infused

Adverse Effects


  •  Avoid concomitant nephrotoxins

  •  Less common with once daily dosing

  •  Greater toxicity with longer duration and supratherapeutic trough levels


Vestibulocochlear toxicity

  • Irreversible

  • recommend audiology testing if prolonged use


  • Can exacerbate neuromuscular blockade

  •  Contraindicated in patients with myasthenia gravis

Major Interactions

Increased nephrotoxicity

  •  Amphotericin

  •  Vancomycin

  •  Cyclosporin

  •  NSAIDs

  •  Contrast dye

Increased ototoxicity

  •  Loop diuretics (e.g. furosemide)

Non-depolarizing muscle relaxants may be potentiated

Additional Information

IV Administration
Dilute in 100 mL D5W or NS and administer over 30-60 min. (60 min for extended interval dosing)

EH Prescribing Restrictions
None (Pharmacist review of therapy)

Community IV Formulary (Metro Area)

A typical Hemodialysis may remove up to 50% of gentamicin.
As such pre-dialysis levels of 1.5 to 3 mg/L are considered acceptable in this population

See EH Intranet for Full Aminoglycoside dosing policies:
PHA-124 Aminoglycoside Antibiotic Monitoring (Adult)
and 210G-MED-040 (Hemodialysys Gentamicin Protocol)


Antimicrobial class: Aminoglycoside

Pregnancy category: D

Average serum half life: 2 hours

Biliary penetration: Moderate

CSF penetration: Poor

Lung penetration: Therapeutic

Urine penetration: Therapeutic