General Information

Pregnancy: Gentamicin crosses the placenta. No reports linking the use of gentamicin to congenital defects have been located. Ototoxicity, which is known to occur after gentamicin therapy in humans, has not been reported as an effect of in utero exposure. However, other aminoglycosides (streptomycin) have been associated with infant ototoxicity following in utero exposure. If gentamicin is required to treat a serious maternal infection, benefit likely outweighs potential risk.

Breastfeeding: Only very small amounts of gentamicin are found in breast milk and gentamicin is poorly orally absorbed. Likely compatible. Monitor infant for gastrointestinal side effects.

  • Chorioamnionitis
  • Endometritis
  • Empiric therapy (in combination) or targeted therapy for suspected or confirmed gram negative infections
  • Empiric therapy for pyelonephritis
  • Used synergistically in enterococcal endocarditis

Consult pharmacy for all patients receiving gentamicin for therapeutic drug monitoring and dose individualization. Monitor creatinine at least 2 - 3 times/week. Formal audiology testing is recommended if therapy is planned to last greater than 2 weeks or symptoms occur. Discontinue if any signs of ototoxicity.

Multiple daily dosing: Serum levels recommended around the third dose following initial therapy or with any change in dose:

  • Pre-dose level: 0 to 30 minutes before next dose (should be less than 2 mg/L)
  • Post-dose level: 30 minutes after completion of an IV infusion (should be 6 - 10 mg/L, target can be lower for urinary tract infections and for synergy)

Once daily dosing: target trough: < 1 mg/L (peak levels not required)

Check gentamicin levels earlier in patients with impaired renal function

  • Nephrotoxicity (non-oliguric) - greater toxicity with longer duration and supratherapeutic trough levels; avoid concomitant nephrotoxins
  • Vestibulocochlear toxicity (irreversible) - requires audiology testing if prolonged use
  • Can exacerbate neuromuscular blockade - e.g. contraindicated in patients with myasthenia gravis

Avoid use with other nephrotoxic agents (ie. vancomycin, NSAIDs, contrast).

Loop diuretics (e.g. furosemide) - increased ototoxicity.

Non-depolarizing muscle relaxants may be potentiated.

In obesity (total body weight (TBW) more than 125% ideal body weight (IBW)), dosing weight is IBW + 0.4 (TBW - IBW). Consult pharmacy.

Formal audiology assessment if planning to use aminoglycoside for greater than 2 weeks or if symptoms develop.

Inform patient of risk of ototoxicity to report any symptoms.

Contraindicated in patients with myasthenia gravis.

Antimicrobial class: Aminoglycoside