Gentamicin

C. diff Risk

Low

Oral Bioavailability

NA

Approximate Cost

$10-30/d

Dosing

Exceptions to use of extended interval dosing: renal dysfunction at baseline; consider alternate antibiotic, synergistic dosing of aminoglycosides with beta-lactams for gram positive infections; use conventional dosing 7 mg/kg/dose IV q24h
Maximum: 400 mg/24h prior to levels

2.5 mg/kg/dose IV q8h

1 mg/kg/dose IV q8h

4-7 mg/kg/dose IV q24h
Maximum: 500 mg/24h prior to levels

5 mg/kg/dose IV q24h
Maximum: 500 mg/24h prior to levels

Post natal age less than or equal to 7 daysPost natal age 8 to 28 daysPost natal age greater than or equal to 29 days5 mg/kg/dose IV q48h4 mg/kg/dose IV q36h4 mg/kg/dose IV q24h

Post natal age less than or equal to 7 daysPost natal age greater than or equal to 8 days4.5 mg/kg/dose IV q36h4 mg/kg/dose IV q24h

4 mg/kg/dose IV q24h

Renally cleared, requires dosage adjustment with changes in renal function. Consult a pharmacist for renal dosing.

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.

Adverse Effects

  • Nephrotoxicity (non-oliguric): less common with once daily dosing; greater toxicity with longer duration and supratherapeutic trough levels; avoid concomitant nephrotoxins

  • Vestibulocochlear toxicity (irreversible): suggest audiology testing if prolonged use

  • Can exacerbate neuromuscular blockade- e.g. contraindicated in patients with myasthenia gravis.

Major Interactions

  • Enhanced nephrotoxic effect with concomitant use of other nephrotoxins

  • Enhanced ototoxicity with loop diuretics (e.g. furosemide)

  • Non-depolarizing muscle relaxants may be potentiated

Pharmacology

Antimicrobial class: Aminoglycoside

Average serum half life: - Neonates: 3-11.5 hours

  • Infants: 4 ± 1 hour

  • Children: 2 ± 1 hour

  • Adolescents:1.5 ± 1 hour

  • Adolescents: 1.5 ± 1 hour

  • Adults: 1.5- 3 hours; End stage renal disease: 30-70 hours

Route of Elimination: Almost completely by glomerular filtration of unchanged drug with excretion into urine.