Canterbury DHB


Antimicrobial Dosing Guidelines (Adults) – Gentamicin/Tobramycin and Vancomycin

In This Section

Gentamicin/Tobramycin Dosing Guidelines (Adults)

Gentamicin/Tobramycin Dosing in Patients with Spinal Injuries (Adults)

Gentamicin Dosing in Patients with Bacterial Endocarditis

Vancomycin Dosing Guidelines (Adults)

Gentamicin/Tobramycin Dosing Guidelines (Adults)

Most patients receive once daily dosing as outlined in the guideline below. Exceptions include patients with:

Calculate the first dose of gentamicin/tobramycin

Prescribe and administer gentamicin/tobramycin

  1. Round dose, where able, to the nearest 40 mg (half of an 80 mg/2 mL vial) for ease of administration. Prescribe in MedChart with frequency set as "variable dose".
  2. Give gentamicin/tobramycin once daily by IV infusion over 30 minutes in 100 mL of sodium chloride 0.9%.
  3. Document times of starting and finishing infusion to enable accurate dose prediction.

Blood sampling

Patients expected to receive only one dose (e.g. for UTIs) do not require blood sampling for gentamicin/tobramycin concentrations. For all other patients, take two blood samples for gentamicin/tobramycin concentrations at:

Document accurate times of blood samples to enable accurate dose prediction. Consult readily with Infectious Diseases/Clinical Microbiology for patients requiring more than one dose.

Follow-up doses

  1. Contact the ward pharmacist during normal working hours with the drug concentration results to get a prediction for the next dose. Alternatively, contact the pharmacist on call after hours (call before 10.30 pm unless the dose must be given before 8 am). Target AUC (24 hours) is 70 – 100 mg/ for most indications.
  2. Repeat 30 minute and 6 to 20 hour samples every 3 days. This may need to be more or less frequent depending on the clinical situation.
  3. Monitor renal function. If it is changing, dose alteration will be required – contact the ward pharmacist. Stop therapy if hearing or vestibular function appears to be affected.
  4. The Department of Infectious Diseases (Respiratory Service, where relevant) must be consulted for any patient being sent home on aminoglycosides for ongoing monitoring. Contact Medicines Information (03 364 0900) for dose predictions for these patients.

Information about this Canterbury DHB document (200409):

Document Owner:

Not assigned (see Who's Who)

Last Updated:

May 2019 (Antimicrobial Dosing Guidelines (Adults) - Gentamicin/Tobramycin and Vancomycin)

Next Review Due:

May 2022


Note: Only the electronic version is controlled. Once printed, this is no longer a controlled document.

Topic Code: 200409