Differences in the adsorption of nafamostat mesilate between polyester-polymer alloy and polysulfone membranes.

We previously experienced severe clot formation in a polyester-polymer alloy (PEPA) dialyzer and hemodialysis (HD) circuit with nafamostat mesilate (NM) as an anticoagulant. The possibility of NM adsorption to the PEPA membrane was taken into consideration, but there was not enough information. In the present study, we evaluated differences in the adsorption of NM between a PEPA membrane (FDX-120 GW, Nikkiso, Tokyo, Japan) and two different polysulfone membranes (FX-140, Fresenius Medical Care, Tokyo, Japan; NV-15U, Toray Medical, Tokyo, Japan). We calculated the NM concentration by measuring absorbance at 241 nm using a spectrometer. NM adsorption was evaluated in three ways. First, we evaluated NM adsorption to hollow fibers. Then, we passed an NM solution through dialyzers and evaluated its adsorption in a single-pass examination. Finally, we circulated an NM solution in an HD circuit using a blood pump and evaluated NM adsorption. In all the experiments, NM adsorption to the PEPA membrane was greater than that to the polysulfone membranes examined. In the blood pump experiment, the estimated adsorption quantities of NM to the PEPA membrane and the FX-140 and NV-15U polysulfone membranes were 12.0 ± 0.1, 1.0 ± 0.1, and 4.1 ± 0.4 mg/m2, respectively. NM adsorption was confirmed, especially in the early phase, and the PEPA membrane adsorbed greater amounts of NM than the polysulfone membranes. We should pay attention to the choice of dialyzer as well as the appropriate dose of NM administration during the preparation of HD circuits.