Use of fondaparinux as an anticoagulant during hemodialysis: a preliminary study.

OBJECTIVE: To study the effect of fondaparinux, a new antithrombotic agent, as an anticoagulant during a 4-hour conventional hemodialysis session. materials and methods: Fondaparinux was administered as an anticoagulant to 16 chronic hemodialysis patients during a single 4-hour hemodialysis session at an intravenous bolus dose of 2.5 mg. Eight patients were using high-flux polyester polymer alloy (PEPA) dialyzers (Group A) and the remainder low-flux polysulfone dialyzers (Group B), whilst all had received conventional doses of tinzaparin sodium as an anticoagulant during the previous month. The dialyzers were primed with 1 l of normal saline containing 5,000 IU of unfractionated heparin. Blood samples for the measurement of INR, APTT (activated partial thromboplastin time) and anti-Xa levels were taken before the study dialysis session (pre), 5 min postdialysis (post), and before the next dialysis session (next). Mean fibrin/clot formation in the extracorporeal circuit and dialyzer was assessed macroscopically by visual inspection and was graded using a 4-point scale. RESULTS: Predialysis anti-Xa levels were 0.04 A+/- 0.03 IU/ml in Group A, and 0.025 A+/- 0.025 IU/ml in Group B (p = NS). Postdialysis anti-Xa levels were significantly higher than predialysis levels in both groups (Group A = 0.16 A+/- 0.04 IU/ml, Group B = 0.46 A+/- 0.12 IU/ml, p < 0.02 for both) and significantly higher in Group B compared to Group A (p < 0.025). Anti-Xa levels before the next dialysis session were 0.06 A+/- 0.04 IU/ml in Group A and 0.25 A+/- 0.06 IU/ml in Group B (p < 0.0001 between Groups A and B). APTT values were significantly higher in postdialysis than predialysis samples for both groups (higher by 27.0 A+/- 26.0% in Group A and 24.3 A+/- 31.9% in Group B). No significant differences were found when comparing APTT values in pre, post and next samples between Groups A and B. No differences were also found between pre, post and next samples for INR values, either within or between groups. Mean fibrin/ clot formation score in the extracorporeal circuit at the end of the study dialysis session was significantly higher in patients of Group A than those of Group B (p < 0.05). Dialysis had to be terminated before the completion of 4 hours in 2 patients of Group A because of the presence of extensive fibrin/clots in the circuit and dialyzer. CONCLUSIONS: Our findings indicate that fondaparinux sodium at an intravenous dose of 2.5 mg can be used successfully as an anticoagulant during a 4-hour conventional hemodialysis session in patients dialyzed with low-flux polysulfone dialyzers, but not in those dialyzed with high-flux dialyzers. However, anti-Xa levels in the former patients were still increased before the next dialysis session, potentially exposing the patients to an increased risk of bleeding.

Comparison of two low-molecular weight heparins (LMWHs), tinzaparin and bemiparin, during hemodialysis.

The anticoagulant effects of two LMWHs, tinzaparin sodium and bemiparin sodium, were compared during two study dialysis (SD) sessions (SD1 with tinzaparin and SD2 with bemiparin) in ten chronic hemodialysis patients. Prior to SD1, patients had received 3,500 IU of tinzaparin in each dialysis session for two weeks. After SD1, they were switched to 3,500 IU of bemiparin for two weeks and the second study dialysis session (SD2) was carried out. Patients used the same dialyzers during the whole study period and no changes were made in any of the other hemodialysis parameters. Blood samples for the measurement of PT, aPTT and anti-Xa activity were taken before the study dialysis sessions (sample 0), and again at two and four hours after the initiation of dialysis (samples 2-h and 4-h, respectively). PT values showed no change between the SD1 and SD2 sessions, but aPTT values were significantly higher in the 2-h and 4-h samples of the SD1 session compared to corresponding values in SD2 samples (p < 0.005). Anti-Xa activity was higher in the 2-h and 4-h samples of the SD2 session compared to the SD 1 session (p = 0.005 and p = 0.012, respectively). At four hours, only patients receiving bemiparin had a mean anti-Xa activity higher than 0.40 IU/mg (mean 0.51 +/- 0.76). However, fibrin/clot formation in the extracorporeal circuit during each study period as assessed by visual inspection, did not differ significantly between sessions. It is concluded that the anticoagulant profile of bemiparin sodium during hemodialysis treatment is superior to that of tinzaparin.