What is the appropriate dose of intravenous (IV) vancomycin for a 60-year-old man with impaired renal function, specifically a creatinine clearance (CrCl) of 50?

Vancomycin Dosing for a 60-Year-Old Man with CrCl 50 mL/min

For a 60-year-old man with a creatinine clearance of 50 mL/min, administer vancomycin 770 mg IV every 24 hours, or alternatively 500-750 mg IV every 12 hours depending on infection severity, with mandatory therapeutic drug monitoring to target appropriate trough concentrations. 1

Initial Dosing Strategy

Loading Dose Consideration

• For serious infections (sepsis, pneumonia, bacteremia), administer a loading dose of 25-30 mg/kg based on actual body weight regardless of renal function, as the loading dose is not affected by renal impairment and is necessary to rapidly achieve therapeutic concentrations 2, 3
• For a 70 kg patient, this would be approximately 1,750-2,100 mg infused over at least 2 hours to minimize infusion-related reactions 3

Maintenance Dosing Based on Renal Function

• The FDA-approved dosing table specifically recommends 770 mg per 24 hours for patients with a creatinine clearance of 50 mL/min 1
• This can be administered as a single daily dose or divided into 500 mg every 12 hours, with the dosing interval being more critical than the individual dose size 1, 4
• The initial maintenance dose should be no less than 15 mg/kg even in patients with moderate renal insufficiency 1

Therapeutic Monitoring Requirements

Target Trough Concentrations

• For serious infections (bacteremia, pneumonia, endocarditis), target trough concentrations of 15-20 mg/L 3, 5
• For less severe infections, target trough concentrations of 10-15 mg/L 3
• Trough levels should be obtained before the fourth or fifth dose at steady state 3

Monitoring Frequency

• Therapeutic drug monitoring is mandatory in patients with renal dysfunction 5
• Monitor trough levels before the fourth dose, then at least weekly or with any change in renal function 5
• The pharmacodynamic target is an AUC/MIC ratio >400, which correlates with clinical efficacy 3, 6

Critical Considerations for Renal Impairment

Dosing Interval Adjustment

• With CrCl of 50 mL/min, extending the dosing interval is more important than reducing individual doses 1, 4
• Every 24-hour dosing is preferred over every 12-hour dosing at this level of renal function to minimize drug accumulation 1
• Some clinicians use 500 mg every 12 hours with close monitoring, but this requires more frequent trough level assessments 4

Common Pitfalls to Avoid

• Do not use standard doses of 1 g every 12 hours in patients with CrCl 50 mL/min, as this will lead to drug accumulation and nephrotoxicity 1, 6
• Avoid targeting high trough levels (15-20 mg/L) for non-severe infections, as this increases nephrotoxicity risk without additional benefit 3
• Elderly patients (>65 years) may require further dose reduction beyond what creatinine clearance suggests, as they often have decreased renal function not fully reflected by calculated CrCl 2, 1

Alternative Dosing Approach

Weight-Based Calculation

• If using weight-based dosing: 15 mg/kg per dose with interval adjusted to every 24-48 hours based on CrCl of 50 mL/min 3, 4
• For a 70 kg patient: approximately 1,000 mg every 24 hours, then adjust based on trough levels 4

Infusion Guidelines

• Administer each dose over at least 60 minutes, or at a rate no faster than 10 mg/min, whichever is longer 1
• For doses >1,000 mg, consider extending infusion time to 90-120 minutes to reduce risk of red man syndrome 1

When to Consider Alternative Therapy

• If vancomycin MIC is ≥2 μg/mL, consider alternative agents (daptomycin, linezolid, ceftaroline) as target AUC/MIC ratios may not be achievable 3, 5
• If nephrotoxicity develops (increase in serum creatinine ≥0.5 mg/dL or ≥50% from baseline after several days of therapy), switch to an alternative agent 3