What are the recommended vancomycin trough (and peak, if applicable) concentrations, timing of draws, and how should these levels guide dosing adjustments?

Vancomycin Therapeutic Drug Monitoring: Peak and Trough Concentrations

Trough Monitoring is the Standard of Care; Peak Levels Are Not Recommended

Trough concentrations are the most accurate and practical method for guiding vancomycin dosing, and peak level monitoring provides no clinical benefit and should not be performed. 1, 2

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Target Trough Concentrations Based on Infection Severity

For Serious/Complicated Infections

• Target trough: 15-20 mg/L for bacteremia, endocarditis, osteomyelitis, meningitis, hospital-acquired pneumonia, and severe skin/soft tissue infections 1, 2, 3
• This range is designed to achieve an AUC/MIC ratio ≥400 for organisms with MIC ≤1 mg/L 1, 2

For Less Severe Infections

• Target trough: 10-15 mg/L for non-complicated infections 2, 3
• Trough monitoring may not be required for uncomplicated skin and soft tissue infections in patients with normal renal function who are not obese 3

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Timing of Trough Level Collection

When to Draw the First Trough

• Obtain the initial trough immediately before the fourth or fifth dose to ensure steady-state conditions have been reached 1, 2, 3
• Steady-state occurs approximately just before the fourth dose 2

Proper Timing Technique

• Draw the trough immediately before the next scheduled dose, not simply at a fixed time interval after the previous dose 3
• For every-12-hour dosing, this means drawing approximately 12 hours after the previous dose, but the critical factor is timing it just before the next administration 3

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Dosing Adjustments Based on Trough Levels

When Trough is Elevated (>20 mg/L)

• Hold the next scheduled dose immediately 1, 2
• Recheck the trough level before administering any subsequent doses 1, 2
• Once the trough decreases to target range (15-20 mg/L), resume vancomycin at a reduced dose or with an extended dosing interval 1
• For patients with normal renal function, consider reducing the dose by approximately 15-20% or extending the dosing interval 1
• Sustained trough concentrations >20 μg/mL significantly increase the risk of nephrotoxicity 1

When Trough is Subtherapeutic

• For serious infections requiring 15-20 mg/L: increase the dose or shorten the dosing interval 3
• For non-severe infections with trough 10-15 mg/L: the current dose may be adequate; assess based on clinical response 3

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Standard Dosing Regimens

Initial Dosing for Adults with Normal Renal Function

• 15-20 mg/kg (actual body weight) every 8-12 hours, not to exceed 2 g per dose 3
• For non-severe infections in non-obese patients: traditional doses of 1 g every 12 hours are typically adequate 3

Loading Dose for Seriously Ill Patients

• 25-30 mg/kg (actual body weight) for patients with sepsis, meningitis, pneumonia, endocarditis, or necrotizing fasciitis 3
• The loading dose is not affected by renal function and should be given at full weight-based dosing even in severe renal impairment 3
• Infuse loading doses over 2 hours to prevent infusion-related reactions 3
• Consider antihistamine premedication for large doses 3

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Why Peak Levels Are Not Recommended

Peak vancomycin concentrations do not need to be measured and provide limited clinical value. 1, 4

• As long as trough concentrations do not exceed 15 mg/L, peak levels will not exceed normally accepted safe concentrations 4
• The AUC/MIC ratio is the pharmacodynamic parameter that best predicts vancomycin efficacy, and this can be adequately estimated from trough levels alone 5
• Monitoring only peak levels is specifically identified as a common pitfall to avoid 1

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Critical Safety Thresholds and Alternative Therapy

When to Switch from Vancomycin

• If vancomycin MIC ≥2 mg/L, switch to an alternative agent (daptomycin, linezolid, or ceftaroline) 1, 2, 3
• Target AUC/MIC ratios are not achievable with conventional dosing when MIC ≥2 mg/L 1, 2

Nephrotoxicity Monitoring

• 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 1
• Concomitant nephrotoxic agents (aminoglycosides, piperacillin-tazobactam, CT contrast, amphotericin B, NSAIDs) significantly increase nephrotoxicity risk 3

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Special Populations Requiring Mandatory Monitoring

Trough monitoring is mandatory for: 1, 2

• Patients with morbid obesity
• Renal dysfunction
• Fluctuating volumes of distribution
• Treatment duration >7 days

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Common Pitfalls to Avoid

• Never continue the same dosage despite elevated trough levels (>20 mg/L), as this increases nephrotoxicity risk 1
• Never monitor peak levels, as they provide no clinical benefit 1
• Never use fixed 1-gram doses in seriously ill patients, as this results in subtherapeutic levels in most patients, especially those weighing >70 kg 3
• Never reduce or omit the loading dose based on renal function, as this delays achievement of therapeutic levels 3
• Never unnecessarily target high trough levels (15-20 mg/L) for non-severe infections, as this increases nephrotoxicity risk 3