Journal of Bioanalysis & Biomedicine

Xabans as Direct Factor X_a Inhibitors

Abstract

Dhrubo Jyoti Sen

Direct factor X_a inhibitors are being used clinically. Clinical trials have shown promise for these compounds as substitutes for the currently administered vitamin K antagonists or low molecular weight heparin. Those trials demonstrated efficacy and safety against warfarin for stroke prevention in atrial fibrillation and against lowmolecular- weight heparin for treatment and secondary prevention of venous thromboembolism or for initial treatment and prevention of venous thromboembolism in patients undergoing hip or knee replacement. Advantages of orally administered direct X_a inhibitors lie in the fact that they have a rapid onset and offset of action which reduces need for “bridging” with a parenteral anticoagulant, that they don’t require frequent monitoring or re-dosing whilst having few strong drug interactions and no food interactions, leading to greater convenience by patients and doctors and that they have a lower risk of intra cranial bleeding in trials. Disadvantages compared to warfarin include the currently limited prospective experience, concerns regarding patient adherence without laboratory monitoring, uncertainty about dosing in some patient populations (eg, renal dysfunction, marked extremes of body weight), their contraindication in severe renal impairment, their lack of specific antidotes and assays to measure drug levels in case of severe bleeding, their potential to overuse in low risk atrial fibrillation people, their short half live affecting efficacy and their higher drug acquisition costs. Direct factor X_a inhibitors (‘xabans’) are a class of anticoagulant drugs which act directly upon Factor X in the coagulation cascade, without using antithrombin as a mediator.