Abstract
Direct oral anticoagulants need no routine monitoring, but measurement of drug levels or activity can be essential in emergent and selected situations. Pharmacokinetic assays measure drug concentration and pharmacodynamic assays measure drug activity on coagulation. However, drug effect on coagulation as measured by a pharmacodynamic assay does not always correlate with drug efficacy as measured by a pharmacokinetic assay. To measure antithrombotic effect, routinely available pharmacodynamic assays are too insensitive to reliably assess low levels of drug concentration where critical decisions need to be made, thus pharmacokinetic assays are used. For emergent situations, however, a readily available and rapid turnaround pharmacokinetic assay is not available. This review discusses the qualities and value of pharmacokinetic and pharmacodynamic assays, summarizes the various assays currently in use, and presents data on a recently developed, whole blood, point of care coagulometer that provides a pharmacodynamic assessment of blood coagulation with sensitivity to the direct oral anticoagulants.