Vancomycin Removal During Hemodialysis
Vancomycin is significantly removed by hemodialysis, particularly with high-flux dialyzers, with approximately 33-40% of the drug being removed during a standard hemodialysis session. 1, 2
Mechanism of Removal
- High-flux dialysis membranes (such as polysulfone, polyarylethersulfone, polyvinylpyrrolidone, and polyamide) significantly increase vancomycin clearance compared to the patient's endogenous clearance (120 ± 59 vs. 9 ± 8 ml/min) 3
- Studies have demonstrated that 17-39.5% of vancomycin is removed during a 3-4 hour high-flux dialysis session 4, 2
- The FDA drug label specifically states that "vancomycin is poorly removed by dialysis," but this statement appears outdated compared to more recent clinical evidence with modern high-flux dialyzers 5
Clinical Implications for Dosing
- Due to significant removal during hemodialysis, the Infectious Diseases Society of America recommends a vancomycin loading dose of 20 mg/kg infused during the last hour of the dialysis session, followed by 500 mg during the last 30 minutes of each subsequent dialysis session 6
- Traditional once-weekly vancomycin dosing results in subtherapeutic levels after 5-7 days and should be abandoned when using high-flux dialyzers 1
- When vancomycin is administered during (rather than after) dialysis, the dose should be increased by approximately 25-40% to account for dialytic removal 7, 2
Pharmacokinetic Considerations
- Post-dialysis redistribution occurs after hemodialysis, with vancomycin levels increasing to approximately 87% of pre-dialysis concentrations due to redistribution from tissue compartments 3
- When vancomycin is administered during the last hour of dialysis, initial serum concentrations are high (77.7 mcg/ml) but fall rapidly to 25.9 mcg/ml by 4 hours post-dialysis 4
- For adequate therapeutic levels, a 30 mg/kg dose administered over the last 2 hours of dialysis achieves similar serum concentrations to the conventional 15 mg/kg dose given after dialysis 4
Monitoring Recommendations
- The National Guidelines for the Judicious Use of Glycopeptides recommend monitoring vancomycin levels twice weekly in hemodialysis patients 6
- Target trough concentrations of 10-25 mcg/ml are appropriate for most infections in hemodialysis patients 1
- Monitoring is particularly important when vancomycin is combined with an aminoglycoside, when using higher than usual doses, or when the patient is dialyzed with high-flux membranes 6
Common Pitfalls to Avoid
- Failing to account for significant vancomycin removal with modern high-flux dialyzers, resulting in subtherapeutic drug levels 1
- Using outdated once-weekly dosing regimens that lead to inadequate drug exposure for several days between doses 1
- Not adjusting the vancomycin dose when administering during (versus after) dialysis sessions 7, 2
- Overlooking the need for therapeutic drug monitoring in hemodialysis patients receiving vancomycin 6