What are the target vancomycin trough levels?

Vancomycin Trough: Definition and Target Levels

A vancomycin trough is a serum drug concentration measured immediately before the next scheduled dose, and it serves as the most accurate and practical method to guide vancomycin dosing. 1, 2

What is a Vancomycin Trough?

• The trough concentration is measured at steady-state conditions, obtained just before the fourth or fifth dose of vancomycin therapy. 1, 2
• This timing ensures that drug levels have stabilized in the body, providing reliable information for dose adjustments. 3
• Peak vancomycin concentration monitoring is not recommended and provides no clinical benefit. 1, 4

Target Trough Concentrations

For Serious/Complicated Infections

For serious infections including bacteremia, infective endocarditis, osteomyelitis, meningitis, hospital-acquired pneumonia, and severe skin/soft tissue infections (such as necrotizing fasciitis), target trough concentrations of 15-20 mg/L. 1, 2, 3

• This range is designed to achieve an AUC/MIC ratio ≥400 for organisms with MIC ≤1 mg/L. 2, 3
• These higher targets apply to critically ill patients with sepsis and invasive MRSA infections. 1

For Less Severe Infections

• For most patients with uncomplicated skin and soft tissue infections who have normal renal function and are not obese, traditional doses of 1 g every 12 hours are adequate, and trough monitoring is not required. 1
• When monitoring is performed for less severe infections, target trough concentrations of 10-15 mg/L. 3

When Trough Monitoring is Mandatory

Trough monitoring is required for patients with:

• Serious or invasive infections (as listed above) 1, 2
• Morbid obesity 1, 2
• Renal dysfunction, including those receiving dialysis 1, 2
• Fluctuating volumes of distribution 1, 2
• Treatment duration exceeding 7 days 2, 3

Management of Elevated Trough Levels

When trough levels exceed 20 mg/L, immediately hold the next scheduled dose and recheck the trough level before administering any subsequent doses. 2, 4

• Sustained trough concentrations >20 μg/mL significantly increase the risk of nephrotoxicity. 2, 4
• Once the trough decreases to the target range, resume vancomycin at a reduced dose (approximately 15-20% reduction) or with an extended dosing interval. 2, 4
• Monitor serum creatinine closely for nephrotoxicity, defined as multiple (at least 2-3 consecutive) increases in serum creatinine of 0.5 mg/dL or 150% increase from baseline. 2, 4

Critical Thresholds for Alternative Therapy

For isolates with vancomycin MIC ≥2 mg/L (VISA or VRSA), an alternative to vancomycin should be used, as target AUC/MIC ratios are not achievable with conventional dosing. 1, 2, 3

• For isolates with MIC <2 mg/L (susceptible by CLSI breakpoints), the patient's clinical response should determine continued use of vancomycin, independent of the MIC. 1

Common Pitfalls to Avoid

• Do not continue the same dosage despite elevated trough levels, as this increases nephrotoxicity risk. 2, 4
• Do not monitor peak levels, as this provides limited clinical value and is not recommended. 1, 4
• Do not discontinue vancomycin therapy completely when still clinically indicated; instead, adjust the dose appropriately. 2, 4
• Do not rely solely on trough concentrations of 15-20 mg/L as a guarantee of efficacy; clinical response remains paramount. 1