Management of Elevated Vancomycin Levels
When vancomycin trough levels exceed 20 mg/L, immediately hold the next scheduled dose and recheck the trough level before administering any subsequent doses. 1
Immediate Action for Elevated Levels
The dose must be suspended (not just reduced) when trough levels exceed 20 mg/L. 2, 1 This is a critical safety threshold because:
- Sustained trough concentrations >20 μg/mL significantly increase nephrotoxicity risk, even in patients on continuous renal replacement therapy (CRRT) 2
- Continuing the same dose when trough exceeds 20 mg/L dramatically increases nephrotoxicity risk and represents a critical error to avoid 1
- Vancomycin-induced nephrotoxicity is defined as multiple increases in serum creatinine of 0.5 mg/dL or 150% increase from baseline 2
Resumption Protocol After Suspension
Once the trough level decreases back to the therapeutic range of 15-20 mg/L:
- Resume vancomycin at a reduced dose (15-20% reduction) or extend the dosing interval 1, 3
- Recheck trough levels with each dose adjustment to ensure appropriate targeting 1
- Monitor serum creatinine at least twice weekly throughout therapy 2, 1
Why Suspension Rather Than Dose Reduction
The guidelines from the Infectious Diseases Society of America, American Society of Health-System Pharmacists, and Society of Infectious Diseases Pharmacists emphasize that subsequent dosage adjustments should be based on actual serum concentrations to achieve targeted therapeutic concentrations 4. This means:
- You cannot safely reduce the dose without first knowing where the level will settle after suspension 4
- The pharmacokinetics in each patient vary based on renal function, volume of distribution, and other factors 5
- Attempting to reduce rather than suspend risks maintaining supratherapeutic levels that continue to cause nephrotoxicity 6
Target Therapeutic Range
For serious infections (bacteremia, endocarditis, osteomyelitis, pneumonia), the target trough is 15-20 mg/L to achieve an AUC/MIC ratio ≥400 for organisms with MIC ≤1 mg/L 1, 6. However, this therapeutic target does not justify exceeding 20 mg/L, as the nephrotoxicity risk outweighs any potential benefit 1.
Special Populations Requiring Vigilance
Patients at highest risk for elevated levels requiring suspension include:
- Those with impaired or fluctuating renal function 5
- Elderly patients who may have greater dosage reductions than expected due to decreased renal function 5
- Patients on CRRT, who still require intensive monitoring despite renal replacement therapy 2
- Morbidly obese patients with altered volumes of distribution 1
Common Pitfall to Avoid
Never continue vancomycin at the same dose or simply reduce it when trough exceeds 20 mg/L without first suspending and rechecking levels. 1 The FDA labeling emphasizes that dosage adjustment must be made in patients with impaired renal function, and measurement of vancomycin serum concentrations is helpful in optimizing therapy, especially in seriously ill patients with changing renal function 5.