5-R-Rivaroxaban is the (R)-enantiomer of Rivaroxaban. Rivaroxaban (BAY 59-7939) is a highly potent and selective direct Factor Xa (FXa) inhibitor with an IC50 of 0.7 nM and a Ki of 0.4 nM.

FXa:0.7 nM

Rivaroxaban competitively inhibits human FXa (Ki 0.4 nM) with >10 000-fold greater selectivity than for other serine proteases; it also inhibits prothrombinase activity (IC50 2.1 nM). Rivaroxaban inhibits endogenous FXa more potently in human and rabbit plasma (IC50 21 nM) than rat plasma (IC50 290 nM). It demonstrates anticoagulant effects in human plasma, doubling prothrombin time (PT) and activates partial thromboplastin time at 0.23 and 0.69 μM, respectively [2].

Rivaroxaban, administered by i.v. bolus before thrombus induction, reduces thrombus formation (ED50 0.1 mg/kg), inhibits FXa, and prolongs PT dose-dependently. PT and FXa are affected slightly at the ED50 (1.8-fold increase and 32% inhibition, respectively). At 0.3 mg/kg (dose leading to almost complete inhibition of thrombus formation), Rivaroxaban moderately prolongs PT (3.2±0.5-fold) and inhibits FXa activity (65±3%) [2].