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Endotoxins and Lipid A Rejection by Ultrafiltration across Highly Permeable Polysulfone Hemodialyzers

Morteza Rafiee-Tehrani a , Dieter Falkenhagen b , Roya Farrokhnia a , Ramin Daneshmir a , and Bernhard Kolmer c

Industrial Pharmacy Research Laboratories, School of Pharmacy, Tehran University of Medical Sciences”, Tehran (Iran), Centre of Biomedical Technology, Danube University b , Krems (Austria), and Coa Chrom Diagnostica c , Vienna (Austria)

The efficiency of endotoxin (LPS) and lipid A rejection of polysulfone high-flux dialyzers was investigated in ultrafiltration experiments. To evaluate the safety of high-flux polysulfone membranes, an in vitro circulation system (measuring endotoxin and lipid a penetrate from the dialyzer to the other side and vice-versa), was utilized. Peritoneal dialysis solution was spiked with various concentrations of Pseudomonas aeruginosa lipopolysaccharide (LPS) as well as lipid A diphosphoryl (E. coli F-583). To monitor the effect of pH on efficiency of polysulfone high-flux hemodialyzers, various pyrogen-free buffer solutions (pH 4.5, 5.5, 6.5, 7.5 and 9.5) were spiked with different concentrations of Pseudomonas aeruginosa endotoxin and E. coli lipid A. Endotoxin and lipid A concentrations were detected by a chromogenic limulus amoebocyte lysate (LAL assay). This study clearly demonstrates that polysulfone dialyzers represent an efficient system to obtain an endotoxin and lipid A-free dialysate when contaminated peritoneal solution was circulated through dialysis ultrafilter. It has been also concluded that there was no pH effect on efficiency of high-flux polysulfone membranes in removing of these pyrogenic substances when different contaminated buffer solutions at different pH values were recirculated.

Key words Dialyzers · Endotoxin · Lipid A · Lipopolysaccharide · Polysulfone membranes · Ultrafiltration