Oral Factor Xa Inhibitors and Clinical Laboratory Monitoring

Abstract

Oral anticoagulation therapy is currently undergoing great changes with the development and use of several new medications. The newer drugs have a more specific mechanism of action for inhibiting coagulation and do not require continuous monitoring like their predecessor. Their efficacy and safety has been proven, but problems arise in the clinical laboratory with developing accurate procedures to measure the therapy when needed. Methods being used are the prothrombin time and anti-factor Xa chromogenic assay which require calibration with the drug being measured. The prothrombinase-induced clotting test shows promise as a measure for Xa inhibitors. The article reviews the oral Factor Xa inhibitor's clinical usefulness, effects on current laboratory coagulation tests and methods for measuring their anticoagulant activity.

ABBREVIATIONS: CYP – cytochrome; DOAC – direct oral anticoagulant; DVT – deep venous thrombosis; INR – international normalized ratio; PE – pulmonary embolism; PiCT – prothrombinase-induced clotting time; PT – prothrombin time; APTT – activated partial thromboplastin time.