CASE REPORTSCoagulation assays in a case of apixaban overdoseGuadarrama, Dennis S.a; DeMarinis, Sandra M.b; Sweeney, Joseph D.a,bAuthor Information aTransfusion Medicine and Coagulation, Roger Williams Hospital bTransfusion Medicine and Coagulation, Rhode Island Hospital, Providence, Rhode Island, USA Correspondence to Joseph D. Sweeney, Blood Bank, Transfusion Medicine and Coagulation, Roger Williams Hospital, 825 Chalkstone Avenue, Providence, RI 02908, USA Tel: +1 401 456 2160; fax: +1 401 456 5755; e-mail: email@example.com Received 21 September, 2017 Revised 7 December, 2017 Accepted 9 January, 2018 Blood Coagulation & Fibrinolysis: March 2018 - Volume 29 - Issue 2 - p 231-235 doi: 10.1097/MBC.0000000000000706 Buy Metrics Abstract Intentional overdose of apixaban is rare and minimal data exist regarding the usefulness of routinely available laboratory tests to predict drug levels. A 50-year-old man was admitted after ingestion of 200-mg apixaban. Serial blood samples were obtained over a 54-h period for assessment of the fall-off in drug levels using the prothrombin time/international normalized ratio and anti-Xa assays and compared with an apixaban-specific chromogenic assay. The prothrombin time/international normalized ratio and anti-Xa assays correlated with the apixaban level when the drug was in the supratherapeutic range (>130 ng/ml) but not in the typical therapeutic trough to peak levels. Apixaban levels are best assessed by a specific anti-Xa test using optimized chromogenic substrates and specific calibrators. A standard anti-Xa test can be a useful surrogate when drug levels are high but use of a specific threshold level for discharge purposes requires caution. Copyright © 2018 YEAR Wolters Kluwer Health, Inc. All rights reserved.