From the Guidelines
Vancomycin trough levels should be monitored to ensure effective and safe therapy, with target ranges of 15-20 mg/L for severe infections like endocarditis, osteomyelitis, meningitis, or MRSA pneumonia, as recommended by the most recent guidelines 1.
Key Considerations
- For typical adult dosing, start with 15-20 mg/kg (actual body weight) every 8-12 hours, with the first trough drawn just before the fourth dose when at steady state 1.
- Adjust dosing based on trough results: increase dose by 25-50% if below target, decrease by 25-50% if above target, and hold doses if trough exceeds 25 mg/L until levels fall below 20 mg/L.
- For patients with renal impairment, extend dosing intervals rather than reducing individual doses, as recommended by the Infectious Diseases Society of America 1.
- Monitor renal function regularly during therapy as vancomycin can cause nephrotoxicity, especially with prolonged treatment, high troughs (>20 mg/L), or concomitant nephrotoxic medications 1.
Rationale
- The optimal dosing strategy for vancomycin involves achieving a trough concentration of 15-20 mg/L to maximize the probability of achieving appropriate pharmacodynamic targets and improving clinical outcomes 1.
- Vancomycin requires therapeutic monitoring because it has a narrow therapeutic window and its pharmacokinetics vary significantly between patients based on renal function, age, and body composition 1.
- Some institutions are moving toward AUC/MIC monitoring instead of troughs, targeting an AUC/MIC ratio of 400-600, which may require fewer blood draws and potentially reduce nephrotoxicity while maintaining efficacy 1.
Important Considerations
- Trough vancomycin monitoring is recommended for serious infections and patients who are morbidly obese, have renal dysfunction (including those receiving dialysis), or have fluctuating volumes of distribution 1.
- Continuous infusion vancomycin regimens are not recommended, as they do not provide a clear benefit over intermittent dosing 1.
From the FDA Drug Label
Measurement of vancomycin serum concentrations can be helpful in optimizing therapy, especially in seriously ill patients with changing renal function. Vancomycin serum concentrations can be determined by use of microbiologic assay, radioimmunoassay, fluorescence polarization immunoassay, fluorescence immunoassay, or high-pressure liquid chromatography
- Vancomycin trough management involves measuring serum concentrations to optimize therapy, particularly in patients with changing renal function.
- The goal is to maintain stable concentrations, and the dose required to achieve this may vary depending on the patient's renal function.
- Key considerations for vancomycin trough management include:
- Initial dose: no less than 15 mg/kg, even in patients with mild to moderate renal insufficiency
- Maintenance dose: may need to be adjusted based on renal function, with more frequent dosing in patients with normal renal function and less frequent dosing in patients with impaired renal function
- Monitoring: serum concentrations should be measured regularly to optimize therapy and prevent toxicity 2
From the Research
Vancomycin Trough Management
- Vancomycin trough levels are an important aspect of managing patients with infections caused by methicillin-resistant Staphylococcus aureus (MRSA) 3, 4.
- The Infectious Diseases Society of America clinical practice guideline recommends targeting trough concentrations of 15-20 mg/L for complicated infections 3.
- Several nomograms have been constructed to achieve optimal trough levels, with initial predicting success rates ranging from 44-76% for non-critically ill patients and 42-84% for critically ill patients 3.
- Using a vancomycin dosing nomogram can significantly improve and accelerate achievement of target trough concentrations, but limited data is available on patients' clinical and microbiological outcomes 3.
Monitoring Vancomycin Trough Levels
- Therapeutic drug monitoring of vancomycin is crucial in clinical decision-making and dosage modification, particularly among patients with decreased kidney function 5.
- Urine vancomycin levels can be used as a noninvasive alternative to blood sampling for monitoring trough levels, especially in patients with normal kidney function 5.
- A positive linear correlation has been found between serum and urine trough levels of vancomycin, with an estimated serum concentration equal to urine vancomycin concentration plus 5.3 mg/L 5.
Risks Associated with High Vancomycin Trough Levels
- High vancomycin trough levels have been associated with an increased risk of nephrotoxicity, with an odds ratio of 2.14 and 95% confidence interval of 1.42-3.23 4.
- However, no significant difference has been found between high and low vancomycin trough levels for mortality or clinical success 4.
- Area under the curve (AUC)-guided dosing strategies have been associated with a lower incidence of vancomycin-induced acute kidney injury compared to trough-guided dosing strategies 6.
Alternative Monitoring Strategies
- AUC-guided dosing strategies may be a more effective approach to managing vancomycin trough levels, with a lower risk of acute kidney injury 6.
- However, further study is needed to fully understand the relationship between vancomycin trough levels and clinical outcomes, as well as the potential benefits and limitations of alternative monitoring strategies 3, 6.