Vancomycin Dosing

When to use vancomycin

The most common use for vancomycin is in invasive Gram positive infections

You need to consider

  • Infection site
  • Patient weight
  • Kidney function
  • Pathogen susceptibility

Pharmacokinetics

  • Vancomycin has bad oral bioavailability so it’s almost never used as a pill
    • Occasionally it is orally to supplement C. diff infections (because that’s going on in the GI tract)
  • Volume of distribution: IV serum 0.4-1 L / kg
  • Normally vancomycin doesn’t cross the blood brain barrier very well, but in the setting of meningitis the inflamed meninges increases permeability

Adverse effects

  • Redman syndrome: A histamine-like flushing during or immediately after dose. Occurs mostly on the face and neck. This is NOT life threatening
    • Treatment: anti-histamine, pause infusion, then restart at a slower rate
    • If the reaction is severe, stop the infusion, give antihistamines, wait until symptoms resolve before restarting. When you restart, give the infusion reaaaalllllly slooooooowly (over more than 4 hours)
  • Nephrotoxicity

Dosing

This is where vancomycin can get tricky, because you are aiming for a target trough (between dose) serum concentrations.

  • Generally the target is 10 mcg/ml, but this may need to be higher for treating MRSA or osteomyelitis
  • Trough concentrations should be measured 30 minutes before the 4th dose any time a course of vanco is started or the dose is changed
  • Monitor creatinine at least once a week (remember that whole nephrotoxicity bit)

Starting dose should be 15-20 mg/kg (based on actual not ideal body weight) every 12 hours. This usually works out to 1-2 g IV Q12H. If the kidneys are not working well, reduce the dose.

References

  • UpToDate.com “Vancomycin: Parenteral dosing, monitoring, and adverse effects in adults”
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