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”