Case series of massive direct oral anticoagulant ingestion-Treatment and pharmacokinetics data

Anticoagulation reversal (vitamin K, prothrombin complex concentrates, idarucizumab, andexanet-α, protamine)

Bleeding events are common in patients prescribed anticoagulants and can have devastating consequences. Several specific and nonspecific agents have been developed to reverse the effects of anticoagulant drugs or toxins. Vitamin K, as the oldest of these antidotes, specifically counteracts the effects of pharmaceuticals and rodenticides designed to deplete stores of vitamin K-dependent factors. In cases of life-threatening bleeding, the addition of prothrombin complex concentrates (PCCs) allows for the immediate replacement of coagulation factors. While the use of PCCs has been extended to the non-specific reversal of the effects of newer direct oral anticoagulants, the specific agents idarucizumab, targeting dabigatran and andexanet-α, binding factor Xa inhibitors, have recently been developed and are being preferentially recommended by most guidelines. However, despite having rapid effects on correcting coagulopathy, there is to date a lack of robust evidence establishing the clear superiority of direct oral anticoagulant-specific reversal agents over PCCs in terms of haemostatic efficacy, safety or mortality. For andexanet-α, a potential signal of increased thromboembolic risks, comparatively high costs and low availability might also limit its use, even though emerging evidence appears to bolster its role in intracranial haemorrhage. Protamine is the specific agent for the reversal of unfractionated heparin anticoagulation used mainly in cardiovascular surgery. It is much less effective for low molecular weight heparin fragments and is usually reserved for cases with life-threatening bleeding.

[Overdosing of direct oral anticoagulants]

BACKGROUND

Direct oral anticoagulants (DOAC) are increasingly used for prophylaxis and treatment of thromboembolic events. Incorrectly dosed DOAC treatment is associated with excess mortality.

PURPOSE

This article aims at raising awareness of DOAC overdosing and its causes as well as presenting a diagnostic and therapeutic work-up.

MATERIAL AND METHODS

Based on a case presentation, a structured review of the current literature on DOAC overdosing was performed and treatment recommendations were extracted.

RESULTS

In addition to wittingly or unwittingly increased DOAC intake, common causes of overdose are inadequate dose adjustment for concomitant medication or comorbidities. Global coagulation testing should be supplemented with DOAC-specific testing. Severe bleeding and the need for invasive diagnostics or urgent surgery represent indications for treating DOAC overdoses. Based on the cause of an DOAC overdose, active charcoal, endoscopic pill rescue, antagonization with idarucizumab or andexanet alfa and the targeted substitution of coagulation factors represent treatment options.

CONCLUSION

The sensitization of clinicians is important to ensure a timely diagnosis and adequate treatment of DOAC overdosing. This report provides an overview of current knowledge on diagnostics and treatment; however, further studies are necessary to improve the existing algorithms.

Complete investigations (autopsy, toxicology, and histology) in a death due to apixaban overdose

The dead body of a 54-year-old man was found at home by his partner. He was off work due to depression. A letter with suicidal intention was present on the scene. He was known to be a heavy drinker, and near the body, an empty bottle of whisky was found. In addition, 2 empty blisters of Eliquis (apixaban) 5 mg, corresponding to 40 tablets, were identified. Apixaban is an oral anticoagulant, acting as a factor Xa inhibitor. Autopsy findings were mostly unremarkable, except numerous bruises and some superficial self-inflected wounds. Histology showed hematomas of calyces and renal pelvis and in the liver, several areas of perivenular haemorrhagic necrosis. Others organs were congestive. Femoral venous blood alcohol was 0.11 g/L. In femoral venous blood, a toxic concentration of apixaban was measured at 1184 ng/mL using LC-MS/MS. Other drugs found at therapeutic concentrations included diazepam (99 ng/mL), nordiazepam (171 ng/mL), flecainide (447 ng/mL), and mianserine (65 ng/mL). Using liquid chromatography coupled to high-resolution mass spectrometry, 2 metabolites were identified, O-desmethyl-apixaban (61.8% of the apixaban response) and hydroxyl-apixaban (4.5% of the apixaban response). Long-term therapy was confirmed by a concentration of 10390 pg/mg in pubic hair.

Bleeding management in patients with direct oral anticoagulants

Bleeding events in patients under direct oral anticoagulation (DOAC) can be life-threating but are commonly not related to drug overdose. However, a relevant DOAC plasma concentration impairs the hemostasis and should therefore be ruled out immediately after hospital admission. The effect of DOAC is typically not visible in standard coagulation tests such as activated partial thrombin time or thromboplastin time. Specific anti-Xa or anti-IIa assays allow a specific drug monitoring, but they are too time-consuming in critical bleeding events and typically not available 24 h/7 d in routine care. Recent advantages in point-of-care (POC) testing might improve patient care by early exclusion of relevant DOAC levels, but sufficient validation is still lacking. POC urine analysis help to exclude DOAC in emergency patients, but does not provide a quantitative information about plasma concentration. POC viscoelastic testing (VET) can determine the DOAC effect on clotting time and helps further to reveal other concomitant bleeding disorders in emergency, e.g., factor deficiency or hyperfibrinolysis. If a relevant plasma concentration of the DOAC is assumed or was proven by either laboratory assays or POC testing, restoration of factor IIa or factor IIa activity is key for effective hemostasis. Limited evidence suggests that specific reversals for DOAC, e.g., idarucizumab for dabigatran and andexanet alfa for apixaban or rivaroxaban, might be superior to increasing thrombin generation by administration of prothrombin complex concentrates. To determinate, if DOAC reversal is indicated or not, time from last intake, anti-Xa/dTT values or results from POC tests can be considered. This experts' opinion provides a feasible decision algorithm for clinical practice.