Vancomycin Dosing in Renal Impairment
For patients with impaired renal function, you must reduce both the dose and extend the dosing interval of vancomycin based on creatinine clearance, with the initial dose being no less than 15 mg/kg even in mild-to-moderate renal insufficiency, followed by maintenance dosing calculated as approximately 15 times the glomerular filtration rate in mL/min per day. 1
Initial Loading Dose Strategy
- Administer a full loading dose of 15 mg/kg regardless of renal function to rapidly achieve therapeutic concentrations, even in patients with mild to moderate renal insufficiency 1
- For critically ill patients with renal impairment, consider increasing the loading dose to 25-30 mg/kg to ensure rapid therapeutic levels 2
- Infuse the loading dose over at least 2 hours (or at a rate no faster than 10 mg/min, whichever is longer) to minimize infusion-related reactions 1
Maintenance Dosing Based on Creatinine Clearance
The FDA label provides a specific dosing table that directly correlates creatinine clearance to daily vancomycin dose 1:
- CrCl 100 mL/min: 1,545 mg/24h 1
- CrCl 90 mL/min: 1,390 mg/24h 1
- CrCl 80 mL/min: 1,235 mg/24h 1
- CrCl 70 mL/min: 1,080 mg/24h 1
- CrCl 60 mL/min: 925 mg/24h 1
- CrCl 50 mL/min: 770 mg/24h 1
- CrCl 40 mL/min: 620 mg/24h 1
- CrCl 30 mL/min: 465 mg/24h 1
- CrCl 20 mL/min: 310 mg/24h 1
- CrCl 10 mL/min: 155 mg/24h 1
Dosing Interval Adjustments
- In patients with marked renal impairment, it is more practical to give maintenance doses of 250-1,000 mg once every several days rather than daily dosing 1
- For functionally anephric patients, give 1,000 mg every 7-10 days after the initial 15 mg/kg loading dose 1
- The maintenance dose required to maintain stable concentrations in anephric patients is 1.9 mg/kg/24h 1
Mandatory Therapeutic Drug Monitoring
- Draw the first trough level before the fourth dose to confirm appropriate dosing in renal impairment 3, 2
- Target trough concentrations of 15-20 mg/L for serious infections (bacteremia, endocarditis, osteomyelitis, meningitis, hospital-acquired pneumonia) 3, 2
- Monitor serum creatinine at least twice weekly throughout therapy in patients with renal impairment 2
- Recheck trough levels with each dose adjustment and more frequently if renal function is fluctuating 2
Critical Considerations for Renal Impairment
- Greater dosage reductions than expected may be necessary in elderly patients due to decreased renal function beyond what creatinine clearance suggests 1
- The standard dosing table is not valid for functionally anephric patients, who require the specific anephric dosing regimen described above 1
- When only serum creatinine is available, calculate creatinine clearance using the Cockcroft-Gault equation, but recognize this overestimates clearance in shock, severe heart failure, oliguria, obesity, liver disease, edema, ascites, debilitation, malnutrition, or inactivity 1
Management of Elevated Trough Levels
- Immediately hold the next dose if trough exceeds 20 mg/L and recheck the level before administering subsequent doses 4, 2
- Sustained trough concentrations >20 μg/mL significantly increase nephrotoxicity risk 4
- Once trough decreases to 15-20 mg/L, resume vancomycin at a reduced dose or with an extended dosing interval 4
- Monitor for nephrotoxicity defined as multiple (at least 2-3 consecutive) increases in serum creatinine of 0.5 mg/dL or 150% increase from baseline 4
Common Pitfalls to Avoid
- Never use standard 1 g every 12 hours dosing in patients with renal impairment without calculating adjusted doses based on creatinine clearance 1
- Do not skip the loading dose in renal impairment—the initial 15 mg/kg dose is essential even with reduced kidney function 1
- Avoid relying on calculated creatinine clearance in patients with unstable renal function, as it does not represent steady state 1
- Never continue the same dose when trough levels exceed 20 mg/L, as this dramatically increases nephrotoxicity risk 2