General Information

Pregnancy: Tobramycin crosses the placenta. No reports linking the use of tobramycin to congenital defects have been located. Ototoxicity, which is known to occur after tobramycin 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 tobramycin is required to treat a serious maternal infection, benefit likely outweighs potential risk.

Breastfeeding: Only very small amounts of tobramycin are found in breast milk and tobramycin is poorly orally absorbed. Likely compatible. Monitor infant for gastrointestinal side effects. Maternal use of an ear drop or eye drop that contains tobramycin presents little or no risk for the nursing infant.

Pseudomonal and other gram negative infections, inhaled form used in cystic fibrosis.

Consult pharmacy for all patients receiving tobramycin 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).

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

Check tobramycin 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) - require audiology testing if prolonged use

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

Increased nephrotoxicity with other nephrotoxins (ie. NSAIDS, contrast dye, vancomycin).

Increased ototoxicity: furosemide.

Neuromuscular blockade agents - respiratory paralysis.

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