Tobramycin

C. diff Risk

Low

Oral Bioavailability

NA

Approximate Cost

$12/day

Dosing

Adult

Conventional Dosing
2mg/kg IV load then 1.7mg/kg IV q8h

High Dose Extended Interval (HDEI)
5-7mg/kg IV q24h IV

General Information

Common Usage

Pseudomonal and other gram negative infections.

Inhaled form used in cystic fibrosis.

Drug Monitoring

Consult pharmacist for level interpretation and dosing.

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

For HDEI
Target Trough <1 ug/mL

For Conventional Dosing
Trough 1-2 ug/mL; Target Peak 4-10 ug/mL

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

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

Adverse Effects

Nephrotoxicity (non-oliguric)

  •  Avoid concomitant nephrotoxins

  •  Less common with HDEI

  •  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 B

  •  Cyclosporine

  •  Cisplatin

  •  NSAIDS

  •  Contrast dye

  •  Vancomycin

Increased ototoxicity

  •  Furosemide

Increased risk of respiratory paralysis

  •  Neuromuscular blockade agents.

Additional Information

Formal audiology assessment at baseline if planning to use aminoglycoside for >7d or if symptoms develop.

Inform patient of risk of ototoxicity and to report any symptoms (oscillopsia, imbalance, hearing loss, tinnitus).

Pharmacology

Antimicrobial class: Aminoglycoside

Pregnancy category: D

Average serum half life: 3.0

Biliary penetration: Moderate

CSF penetration: Poor

Lung penetration: Therapeutic

Urine penetration: Therapeutic