Rivaroxaban (BAY 59-7939) is an orally bioavailable oxazolidinone derivative and direct inhibitor of the coagulation factor Xa with anticoagulant activity. Upon oral administration, rivaroxaban selectively binds to both free factor Xa and factor Xa bound in the prothrombinase complex. This interferes with the conversion of prothrombin (factor II) to thrombin and eventually prevents the formation of cross-linked fibrin clots. Rivaroxaban does not affect existing thrombin levels.

Prothrombinase:2.1 nM, FXa:0.7 nM

在大鼠和兔的动静脉分流模型中,口服Rivaroxaban可减少动脉血栓形成（ED50：5.0 mg/kg和0.6 mg/kg）.在大鼠静脉瘀血模型实验中,静脉注射Rivaroxaban可剂量依赖地减少静脉血栓形成（ED50：0.1 mg/kg）.在狗0.3-3 mg/kg ,大鼠1-10 mg/kg的研究剂量范围内,Rivaroxaban血浆药代动力学呈线性.Rivaroxaban的血浆清除率较低: 狗 0.3 L/(kg·h) ,大鼠0.4 L/(kg·h) ;分布体积(V(ss))稳定: 狗0.4 L/kg,大鼠0.3 L/kg.Rivaroxaban在两种物种中口服的消除半衰期都比较短 (0.9-2.3 h).

Rivaroxaban是一种直接抑制活化X因子口服抑制剂（Ki：0.4 nM）,同时对凝血酶原酶活性也有抑制作用（IC50：2.1 nM）,用于动静脉血栓生成的预防和治疗。对于纯化的人源和兔源FXa,Rivaroxaban亲和性类似（IC50：0.7 nM和0.8 nM）, 但对于大鼠FXa亲和性较差（IC50：3.4 nM）。在血浆中, Rivaroxaban对人和兔内源FXa抑制效果相当（IC50：21 nM）,但在大鼠血浆中的抑制效果较差（IC50：290 nM）。在Caco-2细胞中,Rivaroxaban是具有极化运输特性和高渗透性的P-gp底物, 在体外实验中,即使到100 μM仍然不影响P-gp介导的药物运输。

Factor Xa Activity : The activity of Rivaroxaban against purified serine proteases is measured using chromogenic or fluorogenic substrates in 96-well microtiter plates. The enzymes are incubated with Rivaroxaban or its solvent, dimethyl sulfoxide (DMSO), for 10 minutes. The reactions are initiated by the addition of the substrate, and the color or fluorescence is monitored continuously at 405 nm using a Spectra Rainbow Thermo Reader, or at 630/465 nm using a SPECTRAfluor plus, respectively, for 20 minutes. Enzymatic activity is analyzed in the following buffers (final concentrations): human FXa (0.5 nM), rabbit FXa (2 nM), rat FXa (10 nM), or urokinase (4 nM) in 50 mM Tris–HCl buffer pH 8.3, 150 mM NaCl, and 0.1% bovine serum albumin (BSA); Pefachrome FXa (50–800 μM) or chromozym U (250 μM) with thrombin (0.69 nM), trypsin (2.2 nM), or plasmin (3.2 nM) in 0.1 μM Tris–HCl, pH 8.0, and 20 mM CaCl2; chromozym TH (200 μM), chromozym plasmin (500 μM), or chromozym trypsin (500 μM) with FXIa (1 nM) or APC (10 nM) in 50 mM phosphate buffer, pH 7.4, 150 mM NaCl; and S 2366 (150 or 500 μM) with FVIIa (1 nM) and tissue factor (3 nM) in 50 mM Tris–HCl buffer,pH 8.0, 100 mM NaCl, 5 mM CaCl2 and 0.3% BSA, H-D-Phe-Pro-Arg-6-amino-1-naphthalene-benzylsulfonamide-Water (100 μM) and measured for 3 hours. The FIXaβ/FX assay, comprising FIXaβ (8.8 nM) and FX (9.5 nM) in 50 mM Tris–HCl buffer, pH 7.4, 100 mM NaCl, 5 mM CaCl2 and 0.1% BSA, is started by the addition of I-1100 (50 μM), and measured for 60 minutes. The inhibitory constant (Ki) against FXa is calculated according to the Cheng–Prusoff equation. The IC50 is the amount of inhibitor required to diminish the initial velocity of the control by 50%.

LLC-PK1 and L-MDR1 cells are seeded in 96-well culture plates with microporous polycarbonate inserts and grown for 4 days in the same medium as used for cell cultures but without vincristine. The medium is replaced every 2 days. Before running the assay, the culture medium is replaced by HBSS buffer supplemented with 10 mM HEPES. Rivaroxaban are dissolved in DMSO and diluted with transport buffer to the respective final test concentrations (final DMSO concentration is always 1%). For inhibitor studies, the inhibitor is added at the appropriate concentration. counted. After 2 hour incubation at 37 °C, samples are taken from both compartments and, after the addition of ammonium acetate buffer and acetonitrile, are analyzed by LC-MS/M (Only for Reference)