Anti-Xa activity supports using a simple dosing algorithm for tinzaparin for anticoagulation in hemodialysis.

Kirwan, Christopher J; Baig, Zahid F; Platton, Sean; MacCullum, Peter K; Ashman, Neil

BACKGROUND Unfractionated heparin has been traditionally used for anticoagulation during hemodialysis (HD), but more recently low-molecular-weight heparin (LMWH) is being used as an alternative. Anti-Xa activity can be measured as a surrogate of LMWH efficacy. We present 52 patients treated with tinzaparin anticoagulation on HD, confirming that fixed dosing is safe and efficacious with sound pharmacodynamic reason in relation to anti-Xa profiling. METHODS We undertook a prospective audit in a single dialysis unit. All patients were established on a simple anticoagulation protocol for at least 1 month prior to the audit. Blood anti-Xa activity was measured at time 0, 30, 60 and 120 min into and at the end of HD. Efficacy and safety data were collected on the study day and the two sessions before and after it. RESULTS Fifty-two patients were included in the efficacy and safety analysis with 43 patients undergoing anti-Xa analysis (9 sampling errors). Using current consensus (an end-HD anti-Xa activity of <0.4 IU/ml), our fixed-dose protocol resulted in satisfactory safety in all patients tested. Of 260 HD sessions, 10 (4%) had reduced tinzaparin efficacy. During 105 dialysis sessions (21 patients) using an arteriovenous fistula, 4 patients had one episode of minor bleeding and there were 6 episodes (2 patients) of post-needle-compression time greater than 15 min. CONCLUSION Tinzaparin administered thrice weekly as a fixed dose has good efficacy and is well tolerated as an anticoagulant during HD when used according to our protocol.