The Effects of Argatroban on Thrombin Generation and Hemostatic Activation In Vitro

Abstract

We evaluated argatroban, a direct thrombin inhibitor, as a heparin adjunct for anticoagulation. Platelet-poor plasma (PPP) was isolated from blood collected from 12 volunteers. Thrombin generation measurements were performed in donor PPP that was mixed with antithrombin (AT)-poor plasma to yield AT levels of 0%, 20%, 60%, and 100%. Effects of argatroban (0-1.0 microg/mL), heparin (0.25 U/mL), or the combination of argatroban (0.5 microg/mL) and heparin were also studied. The addition of increasing concentrations of argatroban, heparin, or both to donor PPP (AT level approximately 100%) caused progressive decreases in the lag time and peak formation of thrombin generation. Heparin (0.25 U/mL) at small AT concentrations had a minimal effect on lag time or peak thrombin formation; its effectiveness of inhibiting thrombin was directly correlated with the concentration of AT. Argatroban at 0.5 microg/mL was effective in decreasing thrombin formation at both low and normal AT levels, but it was most effective when combined with heparin. Additionally, blood samples were obtained from 47 cardiac surgical patients, and the interaction of heparin (>1.5 U/mL) and AT or argatroban on clot formation was evaluated with kaolin activated clotting times (ACTs). Significant increases of ACTs at all heparin levels were observed with the addition of argatroban (0.125 and 0.25 microg/mL). The addition of AT (0.2 U/mL) to heparinized blood samples further prolonged ACTs. In summary, we showed that argatroban, unlike heparin, could effectively reduce thrombin generation regardless of AT levels and could prolong ACTs in vitro at clinically used concentrations.

Comparison of the anticoagulant effect of a direct thrombin inhibitor and a low molecular weight heparin in an acquired antithrombin deficiency in children with acute lymphoblastic leukaemia treated with l‐asparaginase: an in vitro study

“…Results from the current study showed that the anticoagulant response was decreased over multiple various AT levels, which is in agreement with two other studies (Tanaka et al, 2004(Tanaka et al, , 2005. The anticoagulant response was limited to <40% of maximum until AT levels were above 0AE5 U/ml.…”

High mortality associated with intracardiac and intrapulmonary thromboses after cardiopulmonary bypass

“…It is conceivable that systemic extension of thrombus formation might have been prevented by bivalirudin-mediated thrombin inhibition. A potential use of direct thrombin inhibitors in cases of intravascular thromboses in AT deficiency is yet to be evaluated [22,70,71].…”

Effects of recombinant activated factor VII on thrombin-mediated feedback activation of coagulation

“…In the absence of antithrombin, the CLT was normalized even in the presence of factor VIII deficiency (Table 1). It was speculated that thrombin is capable of extensive substrate cleavage including TAFI in the absence of antithrombin [10,20]. Indeed, an increased peak thrombin level in AT(À)/FVIII(À) plasma underlies increased thrombin substrate (Z-GGR-AMC) cleavage, although the lag time was not affected by antithrombin depletion (Table 2 and Fig.…”

“…The impact of a coagulation factor deficiency on thrombin generation manifests as a prolonged lag time and/or a decrease in the peak height of thrombin generation as calculated from the amount of substrate cleavage. The decrease in anticoagulant (antithrombin) has an opposite effect because thrombin becomes less inhibited by antithrombin, cleaving more substrate [10,11]. To measure the peak level of endogenous thrombin generation, 80 ml normal or factor-deficient plasma was added to microtiter plate wells, followed by the addition of 20 ml diluted Actin FS (1 : 20 dilution; Dade Behring, Marburg, Germany).…”