The patient’s rivaroxaban level, measured by a drug-specific anti-Xa assay (Diagnostica Stago, Asnières sur Seine, France), was 351 (expected therapeutic range 182–408) ng/mL. Initial blood work results showed hemoglobin of 121 (normal 130–180) g/L, creatinine of 99 (normal 60–110) μmol/L, estimated glomerular filtration rate (GFR) of 81 (normal > 60) mL/min, international normalized ratio of 1.6 (normal 0.8–1.2), activated partial thromboplastin time (aPTT) of > 150 (normal 22–35) seconds, and LMWH anti-Xa level of 8.94 (therapeutic range 0.5–1.0) U/mL. The patient’s vital signs were stable, and we observed no evidence of bleeding other than bruising around multiple abdominal injection sites. He had taken his last dose of rivaroxaban 3 days before the current presentation. The injected dalteparin was left over from a previous prescription for 15 000 units daily. Previously, he had switched among several anti-coagulants owing to intolerance or breakthrough thrombosis, including warfarin, various preparations of low-molecular-weight heparin (LMWH) and, most recently, rivaroxaban. The patient’s medical history included depression, heterozygous factor V Leiden mutation and recurrent venous thromboembolism (VTE). Serial monitoring of LMWH anti-Xa levels or activated partial thromboplastin time or both may help to guide therapy.Ī 42-year-old man presented to the emergency department 2 hours after self-injecting 225 000 units of dalteparin (15 prefilled 15 000-unit vials) with intent to self-harm.

Warfarin overdose antidote