From the Guidelines
Vancomycin troughs should be drawn just before the fourth dose of vancomycin in most cases, aiming for levels between 15-20 mg/L for severe infections like endocarditis, osteomyelitis, meningitis, or MRSA pneumonia, as recommended by the Infectious Diseases Society of America 1.
Key Considerations
- The blood sample should be collected within 30 minutes before administering the next dose, when the drug concentration is at its lowest point, to allow the medication to reach steady state in the body and provide the most accurate measurement of the minimum concentration.
- Proper timing of vancomycin troughs is essential for therapeutic drug monitoring to ensure effective bacterial killing while minimizing toxicity risks, particularly nephrotoxicity.
- For patients with renal impairment, trough monitoring becomes even more important, and the timing may need adjustment based on the modified dosing schedule.
- A vancomycin loading dose of 25-30 mg/kg is suggested to rapidly achieve the target trough drug concentration in critically ill patients with sepsis and septic shock 1.
Monitoring and Dosing
- Trough vancomycin monitoring is recommended for serious infections and patients who are morbidly obese, have renal dysfunction, or have fluctuating volumes of distribution 1.
- Vancomycin doses of 15–20 mg/kg/day every 8–12 h are recommended for adult patients on the basis of actual body weight and are adjusted for the patient’s estimated creatinine clearance, not to exceed 2 g per dose 1.
- The pharmacodynamic parameter that best predicts efficacy of vancomycin is the ratio of the area under the curve (AUC) to the MIC (AUC/MIC), and a targeted AUC/MIC of 1400 is recommended for most patients 1.
From the Research
Vancomycin Trough Levels and Nephrotoxicity
- Vancomycin trough levels have been associated with an increased risk of nephrotoxicity, with higher trough levels corresponding to a greater risk of kidney injury 2, 3, 4.
- A study found that vancomycin trough concentrations of >20 mg/L were independently associated with vancomycin-associated nephrotoxicity (VAN) 3.
- Another study suggested that increasing age, increasing body weight, higher vancomycin dose and trough levels, increased vancomycin frequency and duration, critically ill patients, and site of infection were factors associated with significant increases in blood urea and serum creatinine levels with reduction in creatinine clearance 2.
- The relationship between vancomycin trough levels and acute kidney injury (AKI) risk has been evaluated in a meta-analysis, which found that higher initial and maximum trough levels were significantly linked to the development of AKI 4.
Monitoring and Prevention of Nephrotoxicity
- Monitoring of vancomycin serum trough levels and patient status may facilitate the timely prevention of VAN 3.
- Continuous infusion (CI) vancomycin therapy may offer advantages over intermittent infusion (II) therapy, including more reliable monitoring of steady-state serum concentrations and potentially lower risk of kidney injury 5.
- A meta-analysis found that CI vancomycin was associated with a lower relative risk of kidney injury than II therapy, although other studies reported equivocal findings 5.
Target Trough Levels and Dosing
- The target trough level for vancomycin therapy is typically 10-15 or 15-20 mg/L, although the optimal target level may vary depending on the patient population and clinical context 6, 5.
- A study suggested that a cut-off of 15 mg/L detected AKI with a sensitivity of 62.6% and a specificity of 65.5%, while applying a 20 mg/L threshold resulted in a sensitivity of 42.9% and a specificity of 82.5% 4.
- Clearance-based dosing recommendations for CI vancomycin have been proposed, with target steady-state serum concentrations ranging from 17.5 to 27.5 mg/L or AUC24 values ranging from 420 to 660 mg h/L 5.