Vancomycin dosing and monitoring

Appendix 3: IV Vancomycin dosing & Monitoring


Vancomycin levels are monitored to ensure efficacy and to minimise toxicity (mainly nephrotoxicity and ototoxicity)

Step 1 - Give ONE Loading Dose to all patients

Vancomycin Loading Dose

Actual body Weight

IV Vancomycin Loading Dose

IV infusion

<40kg

750mg

In 250ml saline over 90mins

40-59Kg

1 gram

In 250ml saline over 120mins

60-90Kg

1.5 grams

In 500ml saline over 180mins

>90kg

2 grams

in 500ml saline over 240mins

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Step 2 - Maintenance Dose

In normal renal function : 15mg/kg IV every 12 hours at 10am and 10pm

In renal impairment (after loading dose given)

Creatinine clearance*

Vancomycin dose

>50ml/min

15mg/kg q12h (to start 12 hours after loading dose)

20-50ml/min

15mg/kg q24h (to start 24 hours after loading dose)

<20ml/min or haemodialysis

15mg/kg and re-dose once level <20mg/L

*NB: The Cockcroft-Gault equation should be used to calculate creatinine clearance:

Cockcroft-Gault equation

Creatinine clearance ml/min =

N x (140-age) x  weight* (kg)

Serum creatinine (micromol/L)

Where N= 1.23 for males;  1.04 for females

  • Use ideal body weight (IBW) if actual body weight >20% IBW
  • IBW ♂ = ([height(cm) x 0.9] -88)
  • IBW ♀ = ([height9cm) x 0.9] - 92)

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Step 3- Monitoring levels

Send blood to microbiology, with the following information

Target pre-dose (trough) level: 10-20mg/L

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Step 4 - Suggested vancomycin dose adjustments

Pre-dose (trough) level

Suggested dose alteration

<10mg/L

Increase each dose by approx 500mg. NB: max dose 2g BD

10-15mg/L

Desired range 10-20mg/L: no change
Desired range 15-20mg/L: increase each dose by 250mg

15-20mg/L

No change

>20mg/L

Omit next dose(s) until level <20mg/L and then reduce each dose by 500mg

References:

  1. Rybak et al. Therapeutic monitoring of vancomycin in adult patients: A consensus review of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists. Am J Health-Syst Pharm. 2009; 66: 82-98
  2. Thompson A et al. Development and evaluation of vancomycin dosage guidelines designed to achieve new target concentrations. Journal of Antimicrobial Chemotherapy 2009; 63:1050-1057

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Calculating the dose for obese patients

Obese patients (those 20% over their ideal body weight) should receive a reduced dose calculated using these equations providing a dose determining weight Ref3:

  1. Calculate ideal body weight (IBW):
    • IBW ♂ = ([height(cm) x 0.9] -88)
    • IBW ♀ = ([height9cm) x 0.9] - 92)
  2. Dose determining weight = IBW + 0.4(actual body weight – IBW)
  3. Gentamicin dose (mg) : 5mg x dose determining weight (kg)
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References

  1. Freeman C et al. Once-daily dosing of aminoglycosides: review and recommendations for clinical practice, Journal of Antimicrobial Chemotherapy 1997; 39, 677-686.
  2. Gilbert D et al. A randomised comparison of the safety and efficacy of once-daily gentamicin or thrice-daily gentamicin in combination with ticarcillin-clavulanate. American Journal of Medicine 1998; 105, 182-191.
  3. Schwarz S et al. A controlled investigation of the pharmacokinetics of gentamicin and tobramycin in obese subjects. Journal of Infectious Diseases 1978; 138: 499-505.