An Observational Study of the Factor Xa Inhibitors Rivaroxaban and Apixaban as Reported to Eight Poison Centers

Massive Apixaban Overdose Confirmed with Blood Concentrations and Managed Without Bleeding: A Single Case Report

Background: Acute overdoses of apixaban, and other direct oral anticoagulants are relatively uncommon. The number of direct oral anticoagulants prescriptions in the United States is increasing, however reports on patient outcomes after documented overdose are sparse. Case report: A 76-year-old man with a past medical history of atrial fibrillation and taking apixaban 5 mg twice daily presented to the emergency department 10 hours after reportedly ingesting 60-70 of his pills. He was alert and had a normal physical examination. Blood tests demonstrated an INR of 12, platelets of 161 000 cells/mm3, hemoglobin 9.7 g/dL, and creatinine 1.81 mg/dL. He received 60 g of activated charcoal and 4 units of fresh frozen plasma prophylactically. Initial blood apixaban concentration was 4 000 ng/mL. Repeat blood apixaban concentrations were 3 000 ng/mL and 2 200 ng/mL at 7 and 14 hours, respectively (thrapeutic range 91-321 ng/mL for a 5 mg twice daily dose). The hybrid anti-factor Xa activity did not correlate with blood apixaban concentrations. Apixaban elimination followed first-order kinetics with an apparent elimination half-life of 14 hours in the presence of impaired renal function. He did not have any minor or major bleeding events.

Apixaban-Associated Intracranial Hemorrhage in a Patient With Elevated International Normalized Ratio

Apixaban has been associated with prolongation of the international normalized ratio (INR), but data surrounding the extent of elevation and its clinical significance are limited. Due to interaction between apixaban and the prothrombin assay, elevations in INR in patients receiving apixaban are common and not always grounds for concern. However, in high risk patients, elevations can represent a need for closer monitoring. This case summarizes an 82-year-old woman with a history of atrial fibrillation and left middle cerebral artery strokes with no residual deficits. She presented with right-sided hemiparesis and aphasia and underwent a mechanical thrombectomy with TICI 2b recanalization of a left M1 occlusion. Post-thrombectomy, she was found to have a left atrial thrombus and 10 days later was started on apixaban 5 mg twice daily. On the fourth day of apixaban therapy, she experienced an INR increase to 2.3, prompting initiation of a vitamin K challenge for nutritional deficiency. Despite initial improvement, her INR increased to 2.7 a week after apixaban was initiated, coinciding with a decline in mental status and an apixaban peak level of 435.6 ng/mL (reference range 91-321 ng/mL). A computed tomography (CT) scan of her head showed new intracranial hemorrhage in the area of her previous infarction, prompting apixaban reversal with andexanet alfa. Unfortunately, the patient expired. This case report highlights the importance and difficulty in performing therapeutic drug monitoring in patients receiving oral anti-factor Xa inhibitors, revealing a downside to administration of high-risk medications that do not have readily available monitoring.

Direct oral anticoagulants toxicity in children: an overview and practical guide

INTRODUCTION

By increasing use of direct oral anticoagulants (DOACs) in adults and children, gradual increase in the number of intentional or unintentional DOAC poisonings among children is suspected in the near future. Hence, clinicians and pharmacists need to be familiar with the clinical features and management of DOAC-toxicity among pediatric population.

AREAS COVERED

This article provides an overview and practical guide to DOAC-toxicity in pediatrics according to the available clinical evidence.

EXPERT OPINION

Based on limited available data, accidental pediatric ingestion of DOACs can be managed by supportive care in most cases. However, serious toxicity may occur following massive overdose, in presence of underlying disorders (renal or hepatic dysfunction) and concurrent anticoagulant therapy. Activated charcoal is recommended for known recent ingestion of DOACs (within 2-4 hours) to reduce the gastrointestinal absorption. Supportive interventions including local hemostatic measures and volume resuscitation are the cornerstone of management of bleeding. Vitamin K and fresh frozen plasma are ineffective for DOAC reversal and thus are not recommended. Currently, safety and efficacy data regarding the use of specific reversal agents (including idarucizumab and andexanet alfa) and 3-factor or 4-factor prothrombin complex concentrate (PCC) or activated PCC (aPCC) among children with DOAC-associated bleeding are lacking.

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

BACKGROUND

Direct oral anticoagulants (DOAC) are widely used due to favourable benefit/risk ratio. However, consequences of massive ingestion have been poorly investigated.

OBJECTIVES

We aimed to report outcome and pharmacokinetic parameters in patients who massively ingested DOACs.

METHODS

We conducted a 5-year cohort study including consecutive massive DOAC ingestion patients admitted to two critical care departments. Patients were managed in accordance with standards of care. We collected the main history, clinical, laboratory, management and outcome data. The time-course of plasma DOAC concentrations measured using specific assays was modelled.

RESULTS

Twelve patients (3F/9M; age, 55 years [41-63], median [25th-75th percentiles]) were included. Ingestions involved rivaroxaban (n = 7), apixaban (n = 3) and dabigatran (n = 2), with presumed doses of 9.4-fold [5.0-22.0] the full daily dose. Six patients received activated charcoal but no antidote nor blood-derived product. No bleeding was observed. One patient died due to refractory cardiogenic shock related to bisoprolol co-intoxication. Highest observed peak plasma concentrations were 1720 ng/ml (rivaroxaban), 750 ng/ml (apixaban) and 644 ng/ml (dabigatran). Times to reach DOAC concentration below 50 ng/ml were ~20-45 h (rivaroxaban), ~125 h (apixaban) and ~30-50 h (dabigatran). Elimination half-lives were 2.5-25.5 h (rivaroxaban), 22.0 and 36.5 h (apixaban), and 5.8 and 15.5 h (dabigatran), with substantial interindividual variability and prolongation in case of cardiovascular failure related to co-intoxicants. Charcoal administration, even if delayed, may have contributed to limit toxicity, possibly by reducing absorption and/or enteroenteric recycling.

CONCLUSION

No bleeding was observed in this series of massive DOAC ingestions despite elevated plasma concentrations. No patient required specific haemostatic agents. Charcoal administration should be considered to limit toxicity.

Apixaban-Induced Hepatotoxicity

Apixaban is widely used to prevent and manage thromboembolic disease. Due to it being fairly new in the market, we are still understanding its complete risk profile. We present a case of a 61-year-old female with no prior history of liver disease, who developed severe transaminitis shortly after the initiation of apixaban and started trending down after its discontinuation.

Two Cases of Acute Direct Oral Anticoagulant Overdose Without Adverse Effect

We report 2 pediatric patients who had acute overdoses of the direct oral anticoagulants medications. Both patients were managed conservatively; neither required reversal agents or blood products nor had any major or minor bleeding events. With therapeutic usage of direct oral anticoagulants, routine coagulation studies typically are considered insufficient measures of anticoagulation and the preferred chromogenic anti-Factor Xa assay is recommended but not widely available. Using a routine hybrid heparin anti-Factor Xa assay, 1 patient demonstrated a strong linear correlation up to a serum rivaroxaban concentration of 940 ng/mL.

Current use of rivaroxaban in elderly patients with venous thromboembolism (VTE)

Venous thromboembolism (VTE), which is characterized by pulmonary embolism and deep vein thrombosis, has become a serious public concern. Notably, over half of the patients with VTE are over 70 years of age, but elderly patients are at high risk of anti-coagulation and bleeding, which increase with age. Moreover, risk factors and frailty also show a difference between elderly patients and ordinary patients diagnosed with VTE. Rivaroxaban is a direct inhibitor of activated factor Xa and has the advantage of predictable pharmacodynamics and pharmacokinetics, no coagulation monitoring, and few drug interactions. As a first-line therapy for VTE, this drug is more advantageous than traditional therapy and exhibits good efficacy and safety for ordinary patients. However, the effectiveness and safety of rivaroxaban in elderly patients have not been fully elucidated. This article reviewed the use of rivaroxaban in elderly patients, including drug interactions, monitoring, reversal agents of rivaroxaban, and the use of small dosages of rivaroxaban in elderly patients.

Direct Oral Anticoagulants Plasma Levels Measurement: Clinical Usefulness from Trials and Real-World Data

Measurement of direct oral anticoagulants (DOACs) activity is not routinely necessary. Indeed, evaluation of DOACs plasmatic concentration is discouraged for the majority of patients, due to the lack of outcome data supporting this approach. Nevertheless, DOAC measurements may be useful in emergency situations such as serious bleeding events, need for urgent invasive procedures, and acute ischemic stroke or in managing anticoagulation in "special populations" not adequately studied in clinical trials, for example the very elderly or those at the extremes of body weight. The aim of this review is to describe and summarize the methods for DOACs activity evaluation and the settings in which their plasma level measurement may be indicated, analyzing indications from scientific societies and evidence from clinical trials, as well as real world data on the usefulness of DOACs plasma levels "monitoring."

Exploratory Ingestions of Novel Anticoagulants and Antiplatelets: What Is the Risk?

BACKGROUND

Historically, anticoagulants and antiplatelet agents included warfarin and aspirin, respectively. In recent years, numerous novel anticoagulants (eg, direct thrombin inhibitors and factor Xa inhibitors) as well as the adenosine diphosphate receptor antagonists have increased significantly. Little information on the bleeding risk after exploratory ingestion of these agents is available. The primary purpose of this study is to evaluate the bleeding risk of these agents after an exploratory ingestion in children 6 years or younger.

METHODS

This retrospective multicenter poison control center study was conducted on calls between 2005 and 2014. The following agents were included: apixaban, clopidogrel, dabigatran, edoxaban, prasugrel, rivaroxaban, or ticagrelor. Bleeding characteristics and treatment rendered were recorded.

RESULTS

A total of 638 cases were identified. Most cases involved antiplatelet agents. No patient developed any bleeding complication. The administration of charcoal was independent of the amount of drug ingested.

CONCLUSION

Accidental, exploratory ingestions of these agents seem well tolerated, with no patient developing bleeding complications.

Venous Thrombosis in Children with Acute Lymphoblastic Leukemia Treated on DCOG ALL-9 and ALL-10 Protocols: The Effect of Fresh Frozen Plasma

Background  Venous thromboembolism (VTE) is an important complication for treatment of acute lymphoblastic leukemia (ALL) in children. Especially, ALL treatment, with therapeutics such as asparaginase and steroids, increases the thrombotic risk by reduction in procoagulant and anticoagulant proteins. Replacement of deficient natural anticoagulants by administration of fresh frozen plasma (FFP) may have a preventive effect on the occurrence of VTE.

Methods  We retrospectively analyzed all consecutive children (≤18 years) with ALL, treated on the Dutch Childhood Oncology Group (DCOG) ALL-9 and ALL-10 protocols at the Emma Children's Hospital Academic Medical Center between February 1997 and January 2012, to study the effect of FFP on VTE incidence, antithrombin and fibrinogen plasma levels, and VTE risk factors.

Results  In total, 18/205 patients developed VTE (8.8%; 95% confidence interval [CI]: 4.9–12.7%). In all patients, VTE occurred after asparaginase administration. In total, 82/205 patients (40%) received FFP. FFP supplementation did not prevent VTE or alter plasma levels of antithrombin or fibrinogen. In the multivariate analysis, VTE occurred significantly more frequently in children ≥12 years (odds ratio [OR]: 3.89; 95% CI: 1.29–11.73) and treated according to the ALL-10 protocol (OR: 3.71; 95% CI: 1.13–12.17).

Conclusion  FFP supplementation does not seem to be beneficial in the prevention of VTE in pediatric ALL patients. In addition, age ≥12 years and treatment according to the DCOG ALL-10 protocol with intensive and prolonged administration of asparaginase in combination with prednisone are risk factors. There is a need for effective preventive strategies in ALL patients at high risk for VTE.

Reversal of direct oral anticoagulants: Guidance from the Anticoagulation Forum

Two specific reversal agents for direct oral anticoagulants (DOACs) have been approved in the United States: idarucizumab for dabigatran reversal and andexanet alfa for apixaban and rivaroxaban reversal. Non-specific prohemostatic agents such as prothrombin complex concentrate (PCC) and activated PCC have also been used for DOAC reversal. The goal of this document is to provide comprehensive guidance from the Anticoagulation Forum, a North American organization of anticoagulation providers, regarding use of DOAC reversal agents. We discuss indications for reversal, provide guidance on how the individual reversal agents should be administered, and offer suggestions for stewardship at the health system level.

Model-based meta-analysis to evaluate optimal doses of direct oral factor Xa inhibitors in atrial fibrillation patients

The noninferiority of direct oral factor Xa (FXa) inhibitors (rivaroxaban, apixaban, and edoxaban) in treatment of atrial fibrillation were demonstrated compared with warfarin by several large clinical trials; however, subsequent meta-analyses reported a higher risk of major bleeding with rivaroxaban than with the other FXa inhibitors. In the present study, we first estimated the changes of prothrombin time (PT) in 5 randomized trials based on reported population pharmacokinetic and pharmacodynamic models and then carried out a model-based meta-analysis to obtain models describing the relationship between PT changes and the event rates of ischemic stroke/systemic embolism (SE) and of major bleeding. By using the models, we simulated the optimal therapeutic doses for each FXa inhibitor. It was suggested that dose reduction of rivaroxaban from the current 20 mg/d to 10 mg/d would decrease patient deaths from major bleeding (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.64-0.74) with little increase in those for ischemic stroke/SE (HR, 1.11; 95% CI, 1.07-1.20). The overall decrease in the mortality caused by both events was estimated as 5.81 per 10 000 patient-years (95% CI, 3.92-8.16), with an HR of 0.87 (95% CI, 0.83-0.91). For apixaban and edoxaban, no distinct change in the overall mortality was simulated by dose modification. This study suggested that the current dose of rivaroxaban might be excessive and would need to be reduced to decrease the excess risk of major bleeding.

Considerations for routine coagulation monitoring with rivaroxaban: A case report and review of the literature

BACKGROUND

Rivaroxaban is a non-vitamin K antagonist oral anticoagulant that does not require coagulation monitoring based on current recommendations. Our goal is to explore whether routine coagulation monitoring should not be required for all patients receiving oral rivaroxaban, what relationship between routine coagulation abnormalities and bleeding, and how to deal with the above clinical situations through our case and review of the literature.

CASE SUMMARY

We report a 67-year-old woman with a history of atrial fibrillation who presented to the hospital with worsening dyspnea and cough. Based on electrocardiogram, venous compression ultrasonography, and computed tomography pulmonary angiography, the diagnosis of atrial fibrillation, deep venous thrombosis, and acute pulmonary embolism was confirmed. Her coagulation assays and renal function were normal on admission; she was not underweight, did not have a history of hemorrhagic disease, and her CHA2DS2-VAS, HAS-BLED, and simplified Pulmonary Embolism Severity Index scores were 3, 0, and 0, respectively. Oral rivaroxaban (15 mg twice daily) was administered. The following day, she presented gastrointestinal and gum bleeding, combined with coagulation abnormalities. Following cessation of rivaroxaban, her bleeding stopped and tests improved over the next 2 d. Rivaroxaban was begun again 3 d after recovery. However, she again presented with gastrointestinal and gum bleeding and the abnormal tests, and the therapy was discontinued. At 30-d follow-up after discharge, she presented normal coagulation tests without bleeding.

CONCLUSION

Although current guidelines recommend that using non-vitamin K antagonist oral anticoagulants including rivaroxaban do not require coagulation monitoring, a small number of patients may develop routine coagulation test changes and bleeding during rivaroxaban therapy, especially in the elderly. Clinicians should pay attention to these patients and further obtain evidence in practice.

Anti-factor Xa Monitoring and Activated Charcoal for a Pediatric Patient With Rivaroxaban Overdose

Rivaroxaban, an oral anticoagulant, directly inhibits factor Xa (FXa). A 35-month-old boy was brought to the emergency department 15 minutes after ingesting 200 mg of rivaroxaban (16 mg/kg). Activated charcoal (AC) was administered; the patient was observed with monitoring of plasma anti-FXa levels and discharged the following day after an uneventful hospital observation. We identified two case series and seven case reports of potentially toxic rivaroxaban ingestion in the literature. No serious adverse effects were reported. The present case is the first reported use of anti-FXa monitoring after rivaroxaban ingestion. The magnitude of the effect of AC administration in this patient is unclear.

Evaluation of activated charcoal and lipid emulsion treatment in model of acute rivaroxaban toxicity

AIM

Reducing or reversing the toxicity effects of new oral anticoagulants is an important question.The purpose of the present study is to evaluate the effect of lipid emulsion (LE) and Activated Charcoal (AC) therapy on the intoxication of rivaroxaban, on mice.

METHODS

Adult male Balb/c mice weighing approximately 30g were used in the study. Seven groups were assigned, with six mice in each group. Groups were defined; given only rivaroxaban, given only LE, given only AC, after the administration of rivaroxaban LE applied group in the 1st hour, after the administration of rivaroxaban LE applied group in the 3rd hour, after the administration of rivaroxaban AC applied group in the1st hour, after the administration of rivaroxaban AC applied group in the 1st hour and LE applied group in the 3rd hour. PT and Anti-Factor Xa activity were measured in all blood samples from subjects.

RESULTS

A statistically significant difference was found when all groups were compared in terms of mean PT values and Anti-FactorXa values. However, no statistically significant difference was found in the mean PT and Anti-FactorXa values when only rivaroxaban administrated group and after the administration of rivaroxaban LE and/or AC applied groups were compared one to one. No deaths occurred in groups during the observation.

CONCLUSION

Although the administration of either AC or LE alone or in combination resulted in a decrease in the mean values of PT and anti-Factor Xa, in case of rivaroxaban toxicity, but one-to-one comparison of the groups was not statistically significant.

Assessing Bleeding Risk in Patients With Intentional Overdoses of Novel Antiplatelet and Anticoagulant Medications

STUDY OBJECTIVE

In recent years, the use of novel anticoagulants and antiplatelet agents has become widespread. Little is known about the toxicity and bleeding risk of these agents after acute overdose. The primary objective of this study is to evaluate the relative risk of all bleeding and major bleeding in patients with acute overdose of novel antiplatelet and anticoagulant medications.

METHODS

This study is a retrospective study of acute ingestion of apixaban, clopidogrel, ticlopidine, dabigatran, edoxaban, prasugrel, rivaroxaban, and ticagrelor reported to 7 poison control centers in 4 states during a 10-year span. The prevalence of bleeding for each agent was calculated, and hemorrhage was classified as trivial, minor, or major.

RESULTS

A total of 322 acute overdoses were identified, with the majority of cases involving clopidogrel (260; 80.7%). Hemorrhage occurred in 16 cases (4.9%), including 7 cases of clopidogrel, 6 cases of rivaroxaban, 2 cases of dabigatran, and 1 case of apixaban. Most cases of hemorrhage were classified as major (n=9). Comparing the novel anticoagulants with the P2Y12 receptor inhibitors, the relative risk for any bleeding with novel anticoagulant was 6.68 (95% confidence interval 2.63 to 17.1); the relative risk of major bleeding was 18.1 (95% confidence interval 3.85 to 85.0).

CONCLUSION

Acute overdose of novel anticoagulants or antiplatelet agents is associated with a small risk of significant hemorrhage. The risk is greater with the factor Xa inhibitors and direct thrombin inhibitors than with the P2Y12 receptor antagonists.

Anticoagulation therapy for thromboembolism prevention: a case of warfarin-induced skin necrosis in the setting of protein C deficiency

Patients with protein C deficiency are at increased risk for thrombolic diseases. Non-vitamin K antagonist anticoagulant options should be considered in patients with warfarin-induced skin necrosis (WISN) in the setting of protein C. We report a 41-year-old African American male patient with WISN and protein C deficiency who was treated with rivaroxaban followed by dabigatran. After 1 month on rivaroxaban, he began experiencing blood in his stools, unrelenting pain in his lower extremities, found it difficult to obtain medication despite having insurance and as a result did not maintain compliance. He was then assessed at the hospital, symptomatically treated and discharged on dabigatran. After 6 weeks, he reported symptomatic relief and less side effects. This case involved a head-to-head clinical comparison of rivaroxaban and dabigatran as alternatives to warfarin anticoagulation therapy.

Management of Patients on Non-Vitamin K Antagonist Oral Anticoagulants in the Acute Care and Periprocedural Setting: A Scientific Statement From the American Heart Association

Non-vitamin K oral anticoagulants (NOACs) are now widely used as alternatives to warfarin for stroke prevention in atrial fibrillation and management of venous thromboembolism. In clinical practice, there is still widespread uncertainty on how to manage patients on NOACs who bleed or who are at risk for bleeding. Clinical trial data related to NOAC reversal for bleeding and perioperative management are sparse, and recommendations are largely derived from expert opinion. Knowledge of time of last ingestion of the NOAC and renal function is critical to managing these patients given that laboratory measurement is challenging because of the lack of commercially available assays in the United States. Idarucizumab is available as an antidote to rapidly reverse the effects of dabigatran. At present, there is no specific antidote available in the United States for the oral factor Xa inhibitors. Prothrombin concentrate may be considered in life-threatening bleeding. Healthcare institutions should adopt a NOAC reversal and perioperative management protocol developed with multidisciplinary input.

Apixaban-induced liver injury

An 81-year-old woman with well-controlled hypertension presented to the emergency department with new-onset atrial fibrillation with rapid ventricular response. Treatment for atrial fibrillation was initiated, including rate control and anticoagulation with 5 mg of apixaban two times per day for primary stroke prophylaxis. Three days after initiation of apixaban, the patient noted new-onset abdominal pain, worsening shortness of breath and weakness. Laboratory results showed elevated liver enzymes. Workup for elevated transaminase did not reveal any underlying infectious or autoimmune process. Apixaban, a probable cause for the hepatocellular injury, was discontinued and replaced with intravenous unfractionated heparin to bridge anticoagulation with warfarin. The patient's symptoms resolved as her transaminases improved by discontinuation of apixaban. We illustrate this case of drug-induced hepatotoxicity secondary to treatment with apixaban. It is important for physicians to be aware of this rare adverse effect caused by a widely used novel oral anticoagulant.

Medication Error When Switching from Warfarin to Rivaroxaban Leading to Spontaneous Large Ecchymosis of the Abdominal and Chest Wall

Non-vitamin K oral anticoagulant (NOAC) therapy may be inappropriate if prescription was incorrect, the patient’s physiological parameters change, or interacting concomitant medications are erroneously added. The aim of this report was to illustrate inappropriate NOAC prescription in a 78-year-old woman with non-valvular atrial fibrillation and borderline renal dysfunction who was switched from warfarin to rivaroxaban and subsequently developed bruising with hemorrhagic shock and acute on chronic renal failure. Administration of 4-factor prothrombin complex concentrate effectively reversed coagulopathy and stopped bleeding. Retrospective determination of circulating plasma levels of rivaroxaban and warfarin confirmed that excessive anticoagulation was likely due to warfarin that the patient probably continued to take although rivaroxaban was initiated. Pharmacodynamic interaction between rivaroxaban and warfarin may not only be additive but synergistic. In patients at high risk of complications, judicious prescribing and dosing of NOACs, and regular monitoring of concomitant medications and renal function are highly recommended.

Lack of significant bleeding despite large acute rivaroxaban overdose confirmed with whole blood concentrations

BACKGROUND

Since intentional overdose with rivaroxaban is expected to lead to significant coagulopathy and bleeding, prophylactic reversal has been suggested. We report a single massive ingestion confirmed by a blood concentration that was managed with expectant therapy alone.

CASE REPORT

A 71-year-old man with atrial fibrillation, aortic valve replacement, and congestive heart failure presented to the emergency department after an intentional ingestion of 97 (1940 mg total) rivaroxaban tablets in a suicide attempt. Initial laboratories revealed: PT, 60.2 s; INR 7.2; aPTT, 55.7 s; BUN 28 mg/dL; and creatinine 1.2 mg/dL. A whole-blood rivaroxaban concentration obtained on hospital-day three was 160 ng/mL. The patient was admitted for continued observation and the coagulation markers trended downward with no major bleeding events. No reversal agents or blood products were given during his hospitalization.

CONCLUSION

In the setting of a single, acute rivaroxaban overdose, with normal renal function, and no active bleeding, conservative therapy alone may be sufficient.