Fatal dabigatran toxicity secondary to acute renal failure

Idarucizumab (PRAXBIND®) as a sole reversal agent in an unstable hemorrhagic shock patient on an unknown anticoagulant with elevated protime/international normalized ratio (PT/INR)

Dabigatran is a direct oral anticoagulant thrombin inhibitor approved for stroke prophylaxis in patients with non-valvular atrial fibrillation and prophylaxis or treatment of venous thromboembolism. Since approval, there has been increasing concern regarding bleeding risk, predominantly in the elderly population and those with renal disease. We present a case of an 85-year-old female with an unknown medication history, shortness of breath and severe anemia due to an upper gastrointestinal bleed. Laboratory abnormalities were significant for INR 6.43 and serum creatinine 2.21 mg/dL. While in the emergency department the patient decompensated requiring intubation, aggressive crystalloid resuscitation, blood products and initiation of vasopressors. The inability to distinguish between warfarin- and dabigatran-induced coagulopathies paired with the lack of medical information complicated selection of the appropriate anticoagulation reversal agent. In an attempt to prevent a prothrombotic state, prothrombin complex concentrates (PCC) were held and reversal was accomplished with idarucizumab alone, although warfarin-induced coagulopathy remained a possibility. 30 min after administration, repeat PT/INR was 16.1 s and 1.55, respectively. It was later confirmed that the patient was on sole dabigatran therapy. This case highlights the potential for dabigatran to cause extreme elevation in PT/INR in patients with acute renal failure, which may mimic warfarin-induced coagulopathy. Further, it demonstrates significant, rapid correction of abnormal coagulation assays following administration of idarucizumab in a patient with severe INR elevation and suspected dabigatran use.

Use of direct oral anticoagulants for the prevention and treatment of thromboembolic disease in patients with reduced renal function: a short review of the clinical evidence

BACKGROUND

The use of direct oral anticoagulants (DOACs) is restricted by the limitations of clinical trials guiding therapy for patients with renal impairment, as many of these trials excluded patients with severe renal impairment. There are currently four agents available: dabigatran, rivaroxaban, apixaban, and edoxaban. The purpose of this review was to 1) describe current recommended dosing for each DOAC and published postmarketing data, including case reports, on the use of these agents in the renally impaired; and 2) discuss patient adherence and satisfaction and the cost of these agents.

MATERIALS AND METHODS

A literature search was conducted using Medline and Embase with the terms "dabigatran" or "rivaroxaban" or "apixaban" or "edoxaban" and "renal impairment". Clinical trials and case reports describing the use of DOAC therapy in patients with renal impairment were reviewed. A second search was conducted to find articles evaluating patient adherence, patient satisfaction, and pharmacoeconomics of DOACs.

RESULTS

There are a multitude of subgroup and post hoc analyses, as well as six case reports with dabigatran and one case report with apixaban, that provide insight for the clinical use of DOACs in patients with renal impairment. Dabigatran exhibits the greatest level of renal elimination, and there are data from clinical trials and several case reports that warrant reconsideration before use. Other DOACs may be a better option in patients with impaired renal function. Further, data from patient-adherence studies have suggested that DOACs that are dosed daily (rather than twice daily) are optimal and preferred. There does not appear to be a cost difference between DOACs and warfarin therapy.

CONCLUSION

DOAC therapy in patients with impaired renal function requires more critical review of study data, as these patients may have increased risk of bleeding. It is also valuable to consider patient preferences and cost when selecting the appropriate option for oral anticoagulation.

Current knowledge on assessing the effects of and managing bleeding and urgent procedures with direct oral anticoagulants

PURPOSE

Current knowledge on managing major bleeding events with available hemostatic agents, including their combined use with potential reversal agents, in patients taking direct oral anticoagulant (DOACs) is reviewed.

SUMMARY

Over the past five years, a new generation of oral agents, the DOACs, has emerged as commonly used anticoagulants for stroke prevention in non-valvular atrial fibrillation, and treatment or secondary prevention of venous thromboembolism. Management of a bleeding event in the setting of DOAC therapy should take into account the relative risks of bleeding and thrombosis, which will determine the degree of anticoagulant reversal required. In the setting of a major (critical) bleeding event associated with notable blood loss, management may include transfusions of blood products to sustain the function of organ systems, and the availability of specific reversal agents will provide additional options for bleeding management. Beyond withholding the DOAC and providing supportive management that addresses any factors contributing to the bleeding event, clinicians may desire to expedite the removal of any anticoagulation effects. In general, this is accomplished by either removing or neutralizing the anticoagulant or by independently establishing hemostasis.

CONCLUSION

With or without reversal agents, patients may require supportive management such as mechanical pressure, volume support, transfusions of blood products, and, depending on the situation, surgery to repair the bleeding source. Specific reversal agents are currently under development or have recently been approved for the urgent management of bleeding events or the facilitation of invasive procedures in patients receiving DOACs.

Oral anticoagulants and risk of nephropathy

Anticoagulant-related nephropathy, a recently recognized entity, manifests as unexplained acute kidney injury in the setting of excessive anticoagulation with oral agents. Histologic findings in warfarin-related nephropathy include glomerular hemorrhage and renal tubular obstruction by red blood cells. Affected patients are at increased risk of mortality as well as irreversible kidney injury. Patients with chronic kidney disease are particularly vulnerable to this complication. Similar case reports of anticoagulant-related nephropathy have been linked to the more novel oral anticoagulant, dabigatran. Anticoagulant-related nephropathy has been successfully reproduced in rat models. These animal models shed light on the pathogenesis of the disease including the potential role of direct thrombin and protease-activated receptor-1 inhibition. Warfarin and dabigatran also cause an increase in systolic blood pressure in rats, a risk factor for developing nephropathy. This article reviews the current evidence for anticoagulant-related nephropathy and provides data for the suggested possible mechanisms underlying this adverse effect.

Assessment of novel oral anticoagulant use within a community teaching hospital

Background: Novel oral anticoagulants (NOACs) are considered to be at least as effective and safe as warfarin with several advantages such as predictable pharmacokinetics, allowing for standardized dosing without monitoring, a lack of food interactions and fewer drug interactions; however, their misuse could potentially result in patient harm. Objective: To evaluate the appropriate use of the NOACs within a community teaching hospital. Setting: A community teaching hospital in the United States. Method: A retrospective chart review of patients that were prescribed dabigatran, rivaroxaban, or apixaban at our institution from October 2012 through November 2014 was conducted. Main outcome measure: The primary objective was to determine the percentage of patients that were appropriately prescribed NOACs. Secondary objectives were to determine the number of patients who were inappropriately transitioned from warfarin or parenteral anticoagulants to a NOAC or vice versa, the number of incidents when a NOAC was held or discontinued inappropriately before a procedure and the number of bleeding or thrombotic events while taking a NOAC. Results: Of the 113 patients receiving therapy with an NOAC, appropriate prescribing was observed in 79.7%. Dabigatran, rivaroxaban, and apixaban were appropriately prescribed in 73.8%, 88.3%, and 85.8% of patients respectively. Lack of renal dose-adjustment in patients with reduced renal function was the most common reason for inappropriate use (8.8%). Ten out of 38 patients (26%) were inappropriately transitioned from/to other anticoagulants. Two out of six patients underwent a procedure without holding NOACs as recommended prior to surgery. Of all patients receiving NOACs, a total of 3 bleeding incidents were observed, one with each NOAC. Conclusion: The NOACs were appropriately prescribed for the majority of patients within our institution. Future efforts however should focus on ensuring appropriate dose adjustments for renal impairment, procedures for transitioning between NOACs and parenteral anticoagulants, and adequate withholding times for NOACs prior to surgery in order to optimize the management of NOACs usage within our institution.

Global Thrombosis Test - a possible monitoring system for the effects and safety of dabigatran

Background

Dabigatran is an alternative to warfarin (WF) for the thromboprophylaxis of stroke in patients with non-valvular atrial fibrillation (NVAF). The advantage of dabigatran over WF is that monitoring is not required; however, a method to monitor the effect and the safety of dabigatran is not currently available. The Global Thrombosis Test (GTT) is a novel method to assess both clot formation and lysis activities under physiological conditions.

Objective

The aim of this study was to evaluate whether treatment with dabigatran might affect shear-induced thrombi (occlusion time [OT], sec) by the GTT, and to investigate the possibility that the GTT could be useful as a monitoring system for dabigatran.

Patients/Methods

The study population consisted of 50 volunteers and 43 NVAF patients on WF therapy, who were subsequently switched to dabigatran. Using the GTT, the thrombotic status was assessed one day before and 1 month after switching anticoagulation from WF to dabigatran.

Results

The OT was 524.9 ± 17.0 sec in volunteers whereas that of NVAF patients on WF therapy was 581.7 ± 26.3 sec. The switch from WF to dabigatran significantly prolonged OT (784.5 ± 19.3 sec). One patient on WF therapy and 12 patients on dabigatran therapy were shown to have OT > 900 sec.

Conclusion

The GTT could be used to assess the risk of dabigatran-related bleeding complications.

Concerns about the use of new oral anticoagulants for stroke prevention in elderly patients with atrial fibrillation

The prevalence of atrial fibrillation (AF) and the embolic risk increase with age. Elderly AF patients are undertreated with vitamin K antagonists (VKA). The new oral anticoagulants (NOAC) dabigatran, rivaroxaban and apixaban have been shown to be non-inferior to VKA for stroke prevention in AF. We summarize the knowledge about primary and secondary stroke prevention by NOAC in AF patients >75 years of age. A literature search was carried out using the terms 'dabigatran', 'rivaroxaban', 'apixaban', 'elderly', 'octogenarians', 'atrial fibrillation' and 'anticoagulation' from 1998 to 2013. Randomized clinical trials, longitudinal studies, case series and case reports were included. Whereas studies investigating the use of VKA for stroke prevention in the 1990s were carried out by industry-independent institutions, all NOAC-investigating trials were sponsored by the manufacturers of the respective drugs. Frail elderly people were not represented in NOAC-investigating trials because of various exclusion criteria, and only one-third of patients were aged >75 years. A subgroup analysis from the dabigatran-investigating trial indicated that elderly patients might have a higher risk for extracranial bleeding complications with NOAC than with VKA. Further concerns about the use of NOAC in the elderly are the high prevalence of renal insufficiency in AF patients >75 years of age, the largely unknown risk of drug-drug and drug-food interactions, the lack of easily available laboratory monitoring tests of anticoagulant activity and the lack of an antidote. There is a need for independent studies comparing the efficacy and risk of side effects of NOAC with that of VKA in elderly AF patients.

Management of dabigatran-associated intracerebral and intraventricular hemorrhage: a case report

BACKGROUND

Dabigatran is an oral, reversibly bound, direct thrombin inhibitor currently approved in the United States for prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation. In the phase III trial leading to approval of the agent, the incidence of life-threatening bleeding was 1.80%/year in the dabigatran 150 mg twice daily arm. Because there is no direct antidote or reversal agent for this drug, the need to manage life-threatening hemorrhages with procoagulant products will arise.

OBJECTIVE

To describe a case of dabigatran-associated intracerebral and intraventricular hemorrhage and subsequent management with activated prothrombin complex concentrate.

CASE REPORT

An 85-year-old man currently taking dabigatran 150 mg twice daily presented to the Emergency Department for incoordination, expressive aphasia, and weakness. A computed tomography image of his head demonstrated an intracranial hemorrhage. The last dose of dabigatran was approximately 14 h prior to arrival, and conventional coagulation assays (thrombin time and activated partial thromboplastin time) confirmed the presence of dabigatran in the patient's serum. The patient received 27.5 units/kg of activated prothrombin complex concentrate (FEIBA®; Baxter Healthcare Corporation, Deerfield, IL) after an initial intravenous fluid bolus. His activated partial thromboplastin time was not completely normalized by the use of FEIBA; however, the patient's neurological examination slightly improved and remained stable throughout his hospital course despite some intraventricular expansion of the hematoma. After discharge to physical rehabilitation, the patient developed an ischemic cerebrovascular accident and was discharged home on hospice.

CONCLUSION

Due to lack of an available antidote, activated prothrombin complex concentrate was utilized as a nonspecific procoagulant to stabilize an intracerebral hemorrhage in a patient on dabigatran.

Coagulopathy and Extremely Elevated PT/INR after Dabigatran Etexilate Use in a Patient with End-Stage Renal Disease

Introduction. Dabigatran is an oral direct thrombin inhibitor which has been approved for prophylaxis of stroke in patients with atrial fibrillation. The use of dabigatran etexilate increased rapidly due to many benefits. However, questions have been raised constantly regarding the safety of dabigatran etexilate. Case. A 58-year-old Caucasian male with a history of recurrent paroxysmal atrial fibrillation status after pacemaker and end-stage renal disease on hemodialysis came to the Emergency Department with the complaint of severe epistaxis. He had been started on dabigatran 150 mg twice a day about 4 months ago as an outpatient by his cardiologist. His prothrombin time (PT) was 63 seconds with international normalized ratio (INR) of 8.8 and his activated partial thromboplastin time (aPTT) was 105.7 seconds. Otherwise, all labs were unremarkable including the liver function test. Dabigatran was stopped immediately. His INR and aPTT trended downward, reaching normal levels 5 days after admission. Conclusion. Dabigatran is contraindicated in patients with severe kidney insufficiency as it is predominantly excreted via the kidney (~80%). Elderly patients over 75 and patients with chronic renal impairment should be carefully evaluated before starting dabigatran. Despite studies showing only mild increase in aPTT and PT/INR in patients receiving dabigatran, close monitoring may be reasonable in patients with renal insufficiency.

Warfarin-related nephropathy is the tip of the iceberg: direct thrombin inhibitor dabigatran induces glomerular hemorrhage with acute kidney injury in rats

BACKGROUND

Excessive anticoagulation with warfarin can result in acute kidney injury (AKI) by causing glomerular hemorrhage and renal tubular obstruction by red blood cell (RBC) casts in some patients, especially in those with chronic kidney disease (CKD). This condition was described as warfarin-related nephropathy (WRN). Recent evidence suggests that WRN-like syndromes are not confined to anticoagulation with warfarin, but may be seen with other anticoagulants, such as dabigatran. The aim of this study was to investigate dabigatran effects on kidney function in an animal model of CKD and possible pathogenic mechanisms of AKI.

METHODS

Control and 5/6 nephrectomy rats were treated with different doses of dabigatran and protease-activated receptor 1 (PAR-1) inhibitor SCH79797.

RESULTS

Dabigatran resulted in changes in coagulation in rats similar to those in humans at 50 mg/kg/day. Dabigatran resulted in a dose-dependent increase in serum creatinine (Scr) and hematuria in both control and 5/6 nephrectomy rats. SCH79797 also increased Scr and hematuria, more prominent in animals with CKD. Morphologically, numerous RBC tubular casts were seen in 5/6 nephrectomy rats treated with either dabigatran or SCH79797 and only occasional RBC casts in control rats.

CONCLUSIONS

Our data indicate that WRN represents part of a broader syndrome, anticoagulant-related nephropathy (ARN). ARN, at least partially, is mediated via PAR-1. Our findings suggest that not only CKD patients, but other patients as well, are at high risk of developing AKI if the therapeutic range of anticoagulation with dabigatran is exceeded. Close monitoring of kidney function in patients on dabigatran therapy is warranted.

Dabigatran excess: case report and review of the literature

INTRODUCTION

Novel oral anticoagulants are increasingly used for stroke prophylaxis in patients with non-valvular atrial fibrillation. While these agents offer a more predictable pharmacokinetic profile, the lack of readily available laboratory tests to monitor the level of anticoagulation and absence of an antidote or established therapies to reverse the anticoagulant effect make management of cases of over-anticoagulation challenging.

CASE REPORT

In this case report an 87-year-old man with a history of atrial fibrillation presented with dabigatran excess in the setting of life-threatening, acute renal and hepatic failure. The authors review the use of dabigatran in elderly patients, the available data on management of patients with excess anticoagulation, and the potential options for reversal of the anticoagulation effect.

CONCLUSION

Further investigation into reliable means of monitoring and reversing the anticoagulant effect of dabigatran is crucial to the management of such patients.