Vancomycin is dialyzable, but the degree of removal depends heavily on the type of dialysis and the membrane used. With older low-flux membranes, vancomycin removal is minimal (around 17%), which led to a long-standing belief that it was essentially non-dialyzable. Modern high-flux membranes remove roughly 31% of the drug per session, enough to require dose adjustments and careful monitoring.
Why Vancomycin Resists Easy Removal
Vancomycin is a relatively large molecule at 1,448 Daltons, which makes it harder to pull across a dialysis membrane compared to smaller drugs. It also binds to proteins in the blood, though the degree of binding shifts depending on kidney function. In people with normal kidneys, 30% to 55% of vancomycin is protein-bound. In end-stage renal disease, that drops to about 18%, meaning more of the drug is technically “free” and available for removal during dialysis. Even so, its size remains the bigger barrier.
Removal During Intermittent Hemodialysis
The membrane type is the single biggest factor in how much vancomycin a hemodialysis session clears. In critically ill patients studied during extended daily hemodialysis, low-flux membranes removed a median of 17% of vancomycin (range 8% to 38%), while high-flux membranes removed a median of 31% (range 13% to 43%). Clearance rates with high-flux membranes were roughly double those of low-flux on the second day of treatment.
Because most dialysis centers now use high-flux membranes, vancomycin should be treated as a dialyzable drug for practical dosing purposes. The old assumption that you could give a dose and ignore dialysis sessions no longer holds.
The Post-Dialysis Rebound Effect
One important wrinkle: vancomycin levels in the blood bounce back after dialysis ends. Immediately after a session with highly permeable membranes, plasma concentrations drop by about 38% compared to pre-dialysis levels. But five hours later, levels rebound significantly, settling at only about 16% below the pre-dialysis value. This happens because vancomycin stored in tissues redistributes back into the bloodstream once the dialysis machine is no longer pulling it out.
This rebound means that checking a blood level right after dialysis will overestimate how much drug was actually removed. Levels drawn too soon can lead to unnecessary extra dosing.
Removal During Continuous Therapies (CRRT)
Continuous renal replacement therapy, often used in ICU settings, removes vancomycin more consistently than intermittent hemodialysis because it runs around the clock. In patients receiving continuous venovenous haemodiafiltration (CVVHDF), the sieving coefficient for vancomycin is approximately 0.7, meaning about 70% of the free drug in plasma crosses the membrane. CVVHDF clearance of vancomycin averaged 1.8 liters per hour and accounted for roughly 76% of total body clearance in critically ill patients.
That level of removal is substantial. Patients on continuous therapies typically need more frequent dosing or even continuous infusions of vancomycin compared to patients on intermittent hemodialysis.
Removal During Peritoneal Dialysis
Peritoneal dialysis removes vancomycin much more slowly than hemodialysis. In patients on continuous ambulatory peritoneal dialysis (CAPD), dialytic clearance ranges from 1.2 to 2.4 mL per minute, accounting for 20% to 25% of total plasma clearance. Automated peritoneal dialysis removes a slightly higher proportion, around 30%. Because removal is gradual, vancomycin given for peritoneal infections can be dosed directly into the dialysis fluid and will maintain therapeutic levels for longer periods without the sharp peaks and valleys seen with hemodialysis.
When Vancomycin Is Given Relative to Dialysis
For patients on intermittent hemodialysis, vancomycin is traditionally given after the session ends, ensuring the full dose stays in the body until the next treatment. Giving it during the last hour of dialysis is sometimes done for convenience, and one pharmacokinetic analysis found this approach is safe and achieves recommended blood levels even with high-flux membranes. However, infusing vancomycin during dialysis reduced overall drug exposure by about 25% compared to giving it afterward. That trade-off matters when treating serious infections where maintaining adequate drug levels is critical.
A common dosing approach for hemodialysis patients starts with a loading dose of 20 mg/kg intravenously (typically capped between 1,000 mg and 2,000 mg), followed by maintenance doses of around 750 mg after each dialysis session. Current guidelines from IDSA and partnering pharmacy organizations recommend using area-under-the-curve (AUC) guided monitoring rather than simple trough levels, as this approach is both more accurate and safer for adjusting doses over time.
Practical Implications for Monitoring
The variability in vancomycin removal across different dialysis setups makes routine blood level monitoring essential. Factors that shift removal include the membrane pore size, blood flow rate, session duration, and the patient’s own residual kidney function. Two patients on “the same” dialysis schedule can have very different vancomycin clearance rates.
Blood levels should be drawn pre-dialysis rather than immediately post-dialysis, specifically because of the rebound phenomenon. A level drawn right after a session will suggest the drug was removed more than it actually was, potentially leading to overdosing on the replacement dose. Waiting at least several hours, or simply drawing the next pre-dialysis level, gives a more accurate picture of where the patient stands.