Apixaban (BMS-562247-01) is an orally active inhibitor of coagulation factor Xa with anticoagulant activity. Apixaban directly inhibits factor Xa, thereby interfering with the conversion of prothrombin to thrombin and preventing the formation of cross-linked fibrin clots.

FXa (rabbit):0.17 nM(Ki), FXa (human):0.08 nM(Ki)

Apixaban在犬体内具有优良的药代动力学特性：极低间隙(Cl: 0.02 L/kg/h),低体积分布 (Vdss: 0.2 L/kg),半衰期(T1/2: 5.8 h)和口服生物有效性(F: 58%).作用于静脉血栓形成、动静脉分流血栓形成和电介导颈动脉血栓兔子模型,Apixaban能够抗血栓形成,EC50分别为110 nM,270 nM和70 nM.

作用于体外正常人血浆时,Apixaban延长人凝血时间,使凝血酶原时间（3.6 μM）、改良凝血酶原时间（0.37 μM）、活化部分凝血活酶时间（7.4 μM）和HepTest（0.4 μM）延长一倍。Apixaban对人Factor Xa 和兔Factor Xa的抑制具有高选择,Ki分别为0.08和0.17 nM。此外,在PT和APTT实验中,Apixaban对人和兔血浆的效用最高,对大鼠和犬血浆的效果则较低。

Purified FXa is obtained after activation with Russell's viper venom followed by affinity chromatography. The resulting FXa is > 95% pure as judged by sodium dodecylsulfate polyacrylamide gel electrophoresis. The substrate affinity values for FXa, expressed as the Michaelis-Menten-Henri constant (Km), for human, rabbit, rat and dog FXa are determined using the chromogenic substrate S-2765, and are 36, 60, 240 and 70 μM, respectively. The substrate hydrolysis is monitored by measuring absorbance at 405 nm at 25°C for up to 30 min using a SpectraMax 384 Plus plate reader and SoftMax. FXa activity for each substrate and inhibitor concentration pair is determined in duplicate. The Ki values are calculated by non-linear least-squares fitting of the steady-state substrate hydrolysis rates to the equation for competitive inhibition (Equation 1) using GRAFIT, where v equals reactions velocity in OD min?1, Vmax equals maxiumum reaction velocity, S equals substrate concentration, and I equals inhibitor concentration.