Contribution of Adsorption and Hematocrit Levels to Ganciclovir Clearance in an in Vitro Continuous Hemodiafiltration Model.

Estimation of the continuous hemodiafiltration (CHDF) clearance (CLCHDF) of ganciclovir (GCV) is crucial for achieving efficient treatment outcomes. Here, we aimed to clarify the contribution of diafiltration, adsorption, and hematocrit level to the CLCHDF of GCV in an in vitro CHDF model using three membranes: polyacrylonitrile and sodium methallyl sulfonate copolymer coated with polyethylenimine (AN69ST); polymethylmethacrylate (PMMA); and polysulfone (PS). In vitro CHDF was performed with effluent flow rates (Qe) of 800, 1500, and 3000 mL/h. The initial GCV concentration was 10 µg/mL while that of human serum albumin (HSA) was 0 or 5 g/dL. The CLCHDF, diafiltration rates, and adsorption rates were calculated. The whole blood-to-plasma ratio (R) of GCV for a hematocrit of 0.1 to 0.5 was determined using blood samples with 0.5 to 100 µg/mL of GCV. The in vitro CHDF experiment using AN69ST, PMMA, and PS membranes showed that the total CLCHDF values were almost the same as the Qe and not influenced by the HSA concentration. The diafiltration rate exceeded 88.1 ± 2.8% while the adsorption rate was lower than 9.4 ± 9.4% in all conditions. The R value was 1.89 ± 0.11 and was similar at all hematocrit levels and GCV concentrations. In conclusion, diafiltration mainly contributes to the CLCHDF of GCV, rather than adsorption. Hematocrit levels might not affect the relationship between the plasma and blood CLCHDF of GCV, and the CLCHDF of GCV can be estimated from the Qe and R, at least in vitro.

In vitro analysis of factors affecting the continuous hemodiafiltration clearance of teicoplanin.

BACKGROUND: In the treatment of sepsis, continuous hemodiafiltration (CHDF) and the administration of antibiotics such as teicoplanin (TEIC) are frequently performed in parallel. We aimed to clarify the factors influencing the CHDF clearance (CLCHDF ) of TEIC using a polymethylmethacrylate (PMMA) membrane or a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST). We also investigated whether the adsorption of TEIC onto the hemofilters inhibits the adsorption of interleukin (IL)-6 onto the membranes. METHODS: TEIC, human serum albumin (HSA), and IL-6 were incubated with pieces of hemofilter membranes and adsorption rates were calculated. The CLCHDF , diafiltration rate, and adsorption rate of TEIC were calculated using an in vitro CHDF circuit model. RESULTS: The adsorption rates of TEIC onto the pieces of PMMA and AN69ST membranes ranged from 15.0% to 100% and from -10% to 5%, respectively. The adsorption rate of IL-6 was similar with or without TEIC. The CLCHDF and adsorption rate of TEIC under PMMA-CHDF depended on HSA, but not on effluent flow rate (Qe). The CLCHDF under AN69ST-CHDF depended on HSA and Qe. The observed CLCHDF under AN69ST-CHDF was similar to the predicted value (the product of Qe and the plasma unbound fraction). The observed CLCHDF under PMMA-CHDF was 2.0-7.8 times greater than the predicted value. CONCLUSIONS: Adsorption mainly contributes to the CLCHDF of TEIC using PMMA membranes, whereas diafiltration mainly contributes to the CLCHDF of TEIC using AN69ST membranes. TEIC adsorption might not affect the adsorption of IL-6 onto PMMA membrane.

Contribution of diafiltration and adsorption to vancomycin clearance in a continuous hemodiafiltration circuit model in vitro.

BACKGROUND: Vancomycin (VCM) is eliminated mainly by diafiltration under continuous hemodiafiltration (CHDF), but the contribution of adsorption to CHDF clearance (CLCHDF ) of VCM using a polyacrylonitrile and sodium methallyl sulfonate copolymer membrane coated with polyethylenimine (AN69ST) or a polymethylmethacrylate (PMMA) membrane is unknown. This study sought to investigate the contribution of diafiltration and adsorption to the CLCHDF of VCM using AN69ST and PMMA membranes in vitro. METHODS: An in vitro CHDF circuit model was developed. The initial concentration of VCM was 50 µg/mL and human serum albumin (HSA) was prepared at a concentration of 0, 2.5, or 5.0 g/dL. The effluent flow rate (Qe) was set at 800, 1500, or 3000 mL/h. The CLCHDF , diafiltration rate, and adsorption rate of VCM were calculated. RESULTS: Total CLCHDF of VCM using the AN69ST membrane increased and decreased with increasing Qe and HSA concentration, respectively. Diafiltration and adsorption rates were 82.1 ± 9.8% and 12.1 ± 6.1% under all conditions, respectively. Total CLCHDF using the PMMA membrane increased with increasing Qe. Diafiltration and adsorption rates were 89.2 ± 20.4% and 4.6 ± 17.0% under all conditions, respectively. The observed CLCHDF values significantly correlated with the predicted CLCHDF , calculated according to a previous study as the product of Qe and the plasma unbound fraction. CONCLUSIONS: Diafiltration predominantly contributed to CLCHDF of VCM using AN69ST and PMMA membranes. When diafiltration rather than adsorption mainly contributes to the CLCHDF of VCM, the CLCHDF could be predicted from the Qe and HSA concentration, at least in vitro.