A Low Rivaroxaban Plasma Level May Indicate Anticoagulation Undertreatment

Few reports have been published on the correlation between plasma concentrations of rivaroxaban and clinical outcome in patients who have experienced venous thromboembolism. This article describes the case of a 44-year-old woman who experienced deep vein thrombosis during anticoagulation therapy with rivaroxaban, with evidence of repeated low plasma levels of the drug. We postulate that the determination of plasma rivaroxaban anti-Xa activity can be useful in the evaluation of anticoagulation therapy in selected cases. LEARNING POINTS: Some patients with deep vein thrombosis do not respond to rivaroxaban therapy. Accurate determination of rivaroxaban plasma concentrations is important in clinical practice. The clinical value of rivaroxaban plasma concentrations might be limited by intra- and inter-individual variations.