Included in this total were 1,262 patients (618 in the apixaban group) of age 75 or older, 1,004 patients (499 in the apixaban group) with low body weight (≤60 kg), 1,495 patients (743 in the apixaban group) with BMI ≥33 kg/m 2, and 415 patients (203 in the apixaban group) with moderate renal impairment. A total of 8,464 patients were randomised in two pivotal, double-blind, multi-national studies, comparing apixaban 2.5 mg given orally twice daily (4,236 patients) or enoxaparin 40 mg once daily (4,228 patients). (See Table 1.)Īlthough treatment with apixaban does not require routine monitoring of exposure, a calibrated quantitative anti-Factor Xa assay may be useful in exceptional situations where knowledge of apixaban exposure may help to inform clinical decisions, e.g., overdose and emergency surgery.Ĭlinical efficacy and safety: Prevention of VTE (VTEp): elective hip or knee replacement surgery: The apixaban clinical program was designed to demonstrate the efficacy and safety of apixaban for the prevention of VTE in a broad range of adult patients undergoing elective hip or knee replacement. In patients taking apixaban for the treatment of DVT and PE or prevention of recurrent DVT and PE, the results demonstrate a less than 2.2-fold fluctuation in peak-to-trough levels. In non-valvular atrial fibrillation patients taking apixaban for the prevention of stroke and systemic embolism, the results demonstrate a less than 1.7-fold fluctuation in peak-to-trough levels. In patients taking apixaban for the prevention of VTE following hip or knee replacement surgery, the results demonstrate a less than 1.6-fold fluctuation in peak-to-trough levels. Table 1 as follows shows the predicted steady-state exposure and anti-Factor Xa activity for each indication. The relationship between apixaban plasma concentration and anti-Factor Xa activity is approximately linear over a wide dose range of apixaban. Anti-Factor Xa activity exhibits a close direct linear relationship with apixaban plasma concentration, reaching maximum values at the time of apixaban peak plasma concentrations. Data from clinical trials are only available for the Rotachrom Heparin chromogenic assay. In the thrombin generation assay, apixaban reduced endogenous thrombin potential, a measure of thrombin generation in human plasma.Īpixaban also demonstrates anti-FXa activity as evident by reduction in Factor Xa enzyme activity in multiple commercial anti-FXa kits, however, results differ across kits. They are not recommended to assess the pharmacodynamic effects of apixaban. Changes observed in these clotting tests at the expected therapeutic dose are small and subject to a high degree of variability. As a result of FXa inhibition, apixaban prolongs clotting tests, such as prothrombin time (PT), INR, and activated partial thromboplastin time (aPTT). Pharmacodynamic effects: The pharmacodynamic effects of apixaban are reflective of the mechanism of action (FXa inhibition). Preclinical studies of apixaban in animal models have demonstrated antithrombotic efficacy in the prevention of arterial and venous thrombosis at doses that preserved haemostasis. By inhibiting factor Xa, apixaban prevents thrombin generation and thrombus development. Apixaban has no direct effects on platelet aggregation, but indirectly inhibits platelet aggregation induced by thrombin. Apixaban inhibits free and clot-bound factor Xa, and prothrombinase activity. It does not require antithrombin III for antithrombotic activity. Pharmacology: Pharmacodynamics: Mechanism of action: Apixaban is a potent, oral, reversible, direct and highly selective active site inhibitor of factor Xa. Pharmacotherapeutic group: Antithrombotic agents, direct factor Xa inhibitors.
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