Question: Which clotting factor is inhibited by betrixaban?

Context:
Evaluation of the oral direct factor Xa inhibitor - betrixaban.
Betrixaban , an orally administered direct factor Xa inhibitor, is entering a Phase III trial and undergoing investigation for similar indications as apixaban, dabigatran and rivaroxaban. 
Following the success of the direct thrombin and FXa inhibitors already in the market, new agents are being tested. These include AZD0837, betrixaban, letaxaban, darexaban, and LY517717.
Most are small synthetic molecules that target thrombin (e.g. dabigatran etexilate) or factor Xa (e.g. rivaroxaban, apixaban, edoxaban, betrixaban, YM150). 
They must be modified and standardized for the measurement of direct FXa inhibitors (rivaroxaban, apixaban, edoxaban, betrixaban and others). 
Betrixaban is a novel oral factor Xa inhibitor administered once daily, mostly excreted unchanged in the bile and with low (17%) renal excretion. 
 These newer agents directly target specific steps in coagulation cascade and include newer low molecular weight heparins (adomiparin), ultra low molecular weight heparins (semuloparin, RO-14), inhibitors of activated factor II (dabigatran, AZD0837), X (rivaroxaban, apixaban, edoxaban, betrixaban), IX (REG1,2), XI (antisense oligonucleotides, BMS 262084, clavatadine A), VII/tissue factor (tifacogin, PCI 274836, and BMS 593214), V (recomodulin, solulin), VIII (TB402), dual thrombin/factor X inhibitors (EP21709, tanogitran), and newer vitamin K antagonists (tecarfarin). 
Apixaban, rivaroxaban, endoxaban, and betrixaban are specific direct inhibitors of factor Xa, while dabigatran inhibits factor IIa.
The majority of the drugs in development belong to the class of direct factor Xa inhibitors (the -xabans). These include betrixaban, letaxaban, darexaban, eribaxaban, and LY517717.
Examples of direct factor Xa inhibitors include apixaban, rivaroxaban, otamixaban, betrixaban and edoxaban. 
EXPERT OPINION: A large body of Phase II and Phase III data is now available for FXa inhibitors such as rivaroxaban, apixaban, edoxaban and betrixaban.
Another factor Xa inhibitor, edoxaban, is under evaluation in an ongoing phase III clinical trial and others such as AZD0837, betrixaban and darexaban are still in safety and tolerability phase II studies.
Apixaban, betrixaban, edoxaban, and rivaroxaban are small-molecule, selective inhibitors that directly and reversibly bind to the active site of factor Xa. 
Novel oral anticoagulant drugs, the direct thrombin antagonist dabigatran and factor Xa inhibitors such as rivaroxaban, apixaban, edoxaban, and betrixaban are more predictable and convenient anticoagulants in comparison with warfarin, mainly because of the non-requirement of regular laboratory monitoring and dose adjustments.
Recently developed anticoagulants include direct thrombin antagonists such as dabigatran or factor Xa inhibitors such as rivaroxaban, apixaban, betrixaban, and edoxaban. 
Direct factor Xa inhibitors include rivaroxiban, which has shown promising results for VTE prophylaxis and is being studied for VTE treatment, as well as apixaban and betrixaban, which are at earlier stages of clinical validation.
Two direct factor Xa inhibitors are emerging from phase II trials (betrixaban and YM150) and three are being evaluated in phase III trials (apixaban, edoxaban, and rivaroxaban) for the prevention of stroke and systemic emboli in patients with atrial fibrillation. 
Apixaban, rivaroxaban, endoxaban, and betrixaban are specific direct inhibitors of factor Xa, while dabigatran inhibits factor IIa.
[Pharmacologic and clinical characteristics of direct inhibitors of factor Xa: rivaroxaban, apixaban, edoxaban and betrixaban].
Betrixaban is an oral direct inhibitor of factor Xa (FXa) being developed for the prevention of venous thromboembolism (VTE).
A randomized evaluation of betrixaban, an oral factor Xa inhibitor, for prevention of thromboembolic events after total knee replacement (EXPERT).
Betrixaban is a novel oral factor Xa inhibitor administered once daily, mostly excreted unchanged in the bile and with low (17%) renal excretion.
Betrixaban is a new direct factor Xa inhibitor with distinct pharmacological characteristics, including a long half-life, minimal renal clearance and minimal hepatic metabolism.
Novel anticoagulants in clinical testing include orally active direct factor II inhibitors [dabigatran etexilate (BIBR 1048), AZD0837)], parenteral direct factor II inhibitors (flovagatran sodium), orally active direct factor X inhibitors [rivaroxaban (BAY 59-7939), apixaban, betrixaban, YM150, DU-176b, LY-517717, GW813893, TAK-442, PD 0348292] and new parenteral FXa inhibitors [idraparinux, idrabiotaparinux (biotinilated idraparinux; SSR 126517), ultra-low-molecular-weight heparins (ULMWH: AVE5026, RO-14)].
Examples of direct factor Xa inhibitors include apixaban, rivaroxaban, otamixaban, betrixaban and edoxaban.
Betrixaban , an orally administered direct factor Xa inhibitor, is entering a Phase III trial and undergoing investigation for similar indications as apixaban, dabigatran and rivaroxaban.
Nowadays, four new inhibitors of factor Xa are used orally (rivaroxaban, apixaban, edoxaban, betrixaban), and they are at least as efficient as heparins and vitamin K antagonists.
Of interest, a factor Xa decoy, PRT4445, is currently under evaluation in conjunction with betrixaban, and may be a universal reversal agent for all anticoagulants with anti-Xa activity.
Most are small synthetic molecules that target factor IIa (e.g., dabigatran etexilate, AZD-0837) or factor Xa (e.g., rivaroxaban, apixaban, betrixaban, DU176b, idrabiotaparinux).
Discovery of betrixaban (PRT054021), N-(5-chloropyridin-2-yl)-2-(4-(N,N-dimethylcarbamimidoyl)benzamido)-5-methoxybenzamide, a highly potent, selective, and orally efficacious factor Xa inhibitor.
Seven compounds including rivaroxaban, apixaban, betrixaban, and eribaxaban are orally available direct inhibitors of activated factor X currently in development for the prevention and treatment of venous thromboembolism and for thromboprophylaxis in patients with atrial fibrillation or following an acute coronary syndrome.
Apixaban, betrixaban, edoxaban, and rivaroxaban are small-molecule, selective inhibitors that directly and reversibly bind to the active site of factor Xa
These newer agents directly target specific steps in coagulation cascade and include newer low molecular weight heparins (adomiparin), ultra low molecular weight heparins (semuloparin, RO-14), inhibitors of activated factor II (dabigatran, AZD0837), X (rivaroxaban, apixaban, edoxaban, betrixaban), IX (REG1,2), XI (antisense oligonucleotides, BMS 262084, clavatadine A), VII/tissue factor (tifacogin, PCI 274836, and BMS 593214), V (recomodulin, solulin), VIII (TB402), dual thrombin/factor X inhibitors (EP21709, tanogitran), and newer vitamin K antagonists (tecarfarin)
These newer agents directly target specific steps in coagulation cascade and include newer low molecular weight heparins (adomiparin), ultra low molecular weight heparins (semuloparin, RO-14), inhibitors of activated factor II (dabigatran, AZD0837), X (rivaroxaban, apixaban, edoxaban, betrixaban), IX (REG1,2), XI (antisense oligonucleotides, BMS 262084, clavatadine A), VII/tissue factor (tifacogin, PCI 274836, and BMS 593214), V (recomodulin, solulin), VIII (TB402), dual thrombin/factor X inhibitors (EP21709, tanogitran), and newer vitamin K antagonists (tecarfarin)
Betrixaban is an oral direct inhibitor of factor Xa (FXa) being developed for the prevention of venous thromboembolism (VTE)
Betrixaban is a novel oral factor Xa inhibitor administered once daily, mostly excreted unchanged in the bile and with low (17%) renal excretion.
Betrixaban is a new direct factor Xa inhibitor with distinct pharmacological characteristics, including a long half-life, minimal renal clearance and minimal hepatic metabolism
Betrixaban , an orally administered direct factor Xa inhibitor, is entering a Phase III trial and undergoing investigation for similar indications as apixaban, dabigatran and rivaroxaban.
Apixaban, betrixaban, edoxaban, and rivaroxaban are small-molecule, selective inhibitors that directly and reversibly bind to the active site of factor Xa

Answer: Betrixaban is an orally administered direct clotting factor Xa inhibitor.
Exact answer: Xa