was approved by the U.S. Food and Drug Administration in May 2018, under the trade name AndexXa. Mechanism of action Rivaroxaban inhibits both free and bound Factor Xa in the prothrombinase complex. It is a selective direct factor Xa inhibitor with an onset of action of 2.5 to 4 hours. Inhibition of Factor Xa interrupts the intrinsic and extrinsic pathway of the blood coagulation cascade, inhibiting both thrombin formation and development of thrombi. Rivaroxaban does not inhibit thrombin (activated Factor II), and no effects on platelets have been demonstrated. It allows predictable anticoagulation and dose adjustments and routine coagulation monitoring; dietary restrictions are not needed. Unfractionated heparin (UFH), low molecular weight heparin (LMWH), and fondaparinux also inhibit the activity of factor Xa, indirectly, by binding to circulating antithrombin (AT III) and must be injected, whereas the orally active warfarin, phenprocoumon, and acenocoumarol are vitamin K antagonists (VKA), decreasing a number of coagulation factors, including factor X. Rivaroxaban has predictable pharmacokinetics across a wide spectrum of patients (age, gender, weight, race) and has a flat dose response across an eightfold dose range (5–40 mg). The oral bioavailability is dose-dependent. Doses of rivaroxaban under 10 mg can be taken with or without food, as it displayed high bioavailability independent of whether food was consumed or not. If rivaroxaban is given at oral doses of 15 mg or 20 mg, it needs to be taken with food to aid in drug absorption and achieve appropriate bioavailability (≥ 80%). Chemistry Rivaroxaban bears a striking structural similarity to the antibiotic linezolid: both drugs share the same oxazolidinone-derived core structure. Accordingly, rivaroxaban was studied for any possible antimicrobial effects and for the possibility of mitochondrial toxicity, which is a known complication of long-term linezolid use. Studies found that neither rivaroxaban nor its metabolites have any antibiotic effect against Gram-positive bacteria. As for mitochondrial toxicity, in vitro studies published before 2008 found the risk to be low. History Rivaroxaban was initially developed by Bayer. In the United States, it is marketed by Janssen Pharmaceuticals (a part of Johnson & Johnson). It was the first available direct factor Xa inhibitor which is taken by mouth. Society and culture Economics Using rivaroxaban rather than warfarin costs 70 times more, according to Express Scripts Holding Co, the largest U.S. pharmacy benefits manager. As of 2016, Bayer claimed that the drug was licensed in 130 countries and that more than 23