DOAC Pharmacodynamics and Potential Near-patient Decision Making

Direct oral anticoagulant (DOAC) level testing is needed most when decisions cannot wait, including anticoagulation-associated bleeding, urgent surgery, and thrombolysis for acute ischemic stroke. Yet the field remains uncertain about what constitutes a clinically meaningful result. Pharmacokinetic assays estimate drug exposure, whereas functional assays seek to characterize anticoagulant effect; conflating these questions has obscured both research priorities and bedside decision-making. Conventional coagulation assays perform poorly at low DOAC concentrations, where many urgent decisions are made, and widely used thresholds such as 30 or 50 ng/mL are pragmatic, actionable cutoffs rather than biologically anchored thresholds derived from pharmacodynamic dose-response relationships or validated against clinically meaningful outcomes. A growing body of literature also challenges the longstanding characterization of DOACs as having predictable pharmacokinetics. Future research must define how residual drug levels relate to coagulation impairment and, in turn, clinical outcomes such as bleeding. Urgent care requires rapid, analytically reliable near-patient DOAC testing.

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