PB1364 - Weight-adjusted dosing of tinzaparin for thromboprophylaxis in obese patients

Tuesday, July 12, 2022

6:30 PM – 7:30 PM

Location: Exhibition

Presentation Format: In-Person

Presenting Author(s)

CP

Christian Pfrepper, MD

Physician
Division of Hemostaseology, University Hospital Leipzig, Germany
Leipzig, Sachsen, Germany

Co-Author(s)

EK

Elisabeth Koch

Medical Student
Division of Hemostaseology, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen, Germany
MW

Maria Weise

MD
Division of Hemostaseology, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen, Germany
MM

Michael Metze

MD
Department of Cardiology, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen-Anhalt, Germany
RS

Roland Siegemund

PhD
Medical ICU, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen, Germany
AS

Annelie Siegemund

PhD
Division of Hemostaseology, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen, Germany
SP

Sirak Petros

MD
Division of Hemostaseology, University Hospital Leipzig, Leipzig, Germany
Leipzig, Sachsen, Germany

Background: Knowledge about weight-adjusted dosing of tinzaparin for prophylaxis in obese medical patients is limited and it remains unclear whether this approach leads to an accumulation of the drug.

Aims: To evaluate the anti-Xa activity in obese patients on tinzaparin thromboprophylaxis adjusted for actual body weight.

Methods: This prospective study included patients with a body mass index (BMI) ≥ 30 kg/m2 treated with tinzaparin once daily adjusted for actual body weight (table 1). Anti-Xa-, anti-IIa activity, von Willebrand factor (VWF) antigen, VWF activity, factor VIII, D-dimer, prothrombin fragments and thrombin generation were measured four hours after subcutaneous injection between day 1 and 14 after the initiation of tinzaparin.

Results: We included 121 plasma samples from 66 patients (48.5% female), with a median age of 60 (range 23-85) years, a median weight of 125 (range 82-300) kg and a median BMI of 41.9 (range 30.1-88.6) kg/m2. The target anti-Xa activity of 0.2-0.4 IU/mL was achieved in 80 plasma samples (66.1%), 39 (32.2%) were below and two (1.7%) above the target range. The median anti-Xa activity was 0.26 (IQR 0.20-0.31) IU/mL, 0.23 (IQR 0.16-0.28) IU/mL and 0.21 (IQR 0.17-0.26) IU/mL on the days 1-3, 4-6 and 7-14, respectively. The anti-Xa activity was not different between the weight groups (p=0.188), figure 1. Subcutaneous injection into the upper arm compared to the abdomen resulted in a lower endogenous thrombin potential (455 vs. 1533 nmol/L*min, p=0.008), a lower peak thrombin (32 vs. 149 nmol/L, p=0.008) and a trend to a higher anti-Xa activity (0.023 vs 0.020 IU/L, p=0.075).

Conclusion(s): Dosing of tinzaparin adjusted for actual body weight in obese patients seems not to lead to accumulation or overdosing. The majority of patients achieve anti-Xa activity in the target range. In addition, there is a significant difference in thrombin generation depending on the injection site.