Impact of adsorptive CRRT membranes on vancomycin pharmacokinetics in critically ill patients.

Continuous renal replacement therapy (CRRT) is a vital organ support modality for critically ill patients. Adsorptive membranes, particularly AN69ST and oXiris, are increasingly used in clinical practice; however, their impact on the pharmacokinetics of antibiotics with a narrow target concentration range between efficacy and toxicity, such as vancomycin, remains incompletely defined. Considerable heterogeneity exists among available studies. Multiple in vitro dynamic circulation models reported adsorption of 12% to 19.5% of the initial vancomycin dose, whereas some static or open-model in vitro studies failed to detect significant adsorption. Retrospective studies have reported that adsorption accounted for approximately 15.9% with AN69ST membranes and 5.4% with oXiris membranes of total vancomycin elimination. However, the clinical significance of vancomycin removal by adsorptive membranes via adsorption remains unclear and warrants further investigation. Nevertheless, overlooking the additional clearance contributed by AN69ST or oXiris membranes during dose regimen design may lead to subtherapeutic vancomycin exposure, thereby increasing the risk of treatment failure and antimicrobial resistance. This article systematically reviews the current evidence on vancomycin elimination characteristics with adsorptive membranes, with an emphasis on adsorption mechanisms, influencing factors, and clinical dosing adjustment strategies. In current clinical practice, intensified therapeutic drug monitoring with dynamic dose adjustment based on measured concentrations remains an essential strategy to ensure the efficacy and safety of vancomycin therapy. A deeper understanding of membrane-specific adsorption kinetics is required to optimize antibiotic dosing in critically ill patients receiving CRRT with highly adsorptive membranes.