Evaluation of Dosing Practices of Rivaroxaban and Dabigatran

Background: Anticoagulation is standard practice for the prevention and treatment of thromboembolic events. Two of the newer agents, rivaroxaban (Xarelto) and dabigatran (Pradaxa) are being utilized frequently in the inpatient and outpatient settings. Prescribers may not appreciate the need for dose reduction in the setting of renal insufficiency. Objective: The objective of this study was to evaluate whether rivaroxaban and dabigatran were dosed according to recommendations in the package insert for patients with renal insufficiency. Methods: Eligible patients were those >18 years of age who received rivaroxaban or dabigatran as an inpatient or had a prescription filled from the outpatient pharmacy. The use of the Cockcroft–Gault equation was utilized to calculate creatinine clearance to evaluate whether patients had appropriate manufacturer recommended dose reductions based on their renal function. Results: There were very few patients (8 of 355, or 2.3%) who should have received a reduced dose when creatinine clearance was calculated utilizing actual body weight. In those patients with renal insufficiency, 3 of 6 (50.0%) patients receiving rivaroxaban and 1 of 2 (50%) patients receiving dabigatran were appropriately dosed. When ideal body weight was substituted for creatinine clearance calculation, there were 15 patients receiving rivaroxaban and 10 patients receiving dabigatran who fell below the creatinine clearance threshold for dose reduction. Conclusions: Based on this evaluation, very few patients required a dose reduction due to renal insufficiency. It is important for clinicians to always monitor renal function when utilizing these medications to optimize the benefits of the new oral anticoagulants while limiting potential deleterious effects. Furthermore, it is necessary to ensure that actual body weight is being utilized for creatinine clearance calculations with the new oral anticoagulants and not to base dosing on estimated glomerular filtration rate or other calculated creatinine clearance as this could lead to inappropriate dose reductions.

The periprocedural management of novel oral anticoagulants in patients with nonvalvular atrial fibrillation: rationale and a summary of the available evidence from phase 3 clinical trials

The novel oral anticoagulants (NOACs) have rapidly emerged as an alternative therapy to warfarin. Several recent phase 3 randomized control trials have demonstrated the efficacy and safety of the NOACs in the treatment for patients with nonvalvular atrial fibrillation. As the NOACs are incorporated in clinical practice, questions have begun to arise concerning their optimal use in commonly encountered situations. In this review, we provide a summary of the available evidence from the phase 3 randomized control trials specifically with regard to 1 such scenario, the periprocedural management of NOACs, with a goal of providing guidance for practicing clinicians.

Potential antidotes for reversal of old and new oral anticoagulants

The prescription of new oral anticoagulants is on the rise. As opposed to vitamin K antagonists and heparins the new agents have single targets in the coagulation cascade, more predictable pharmacokinetics and they lack validated and available antidotes. In general, the new agents have similar or lower bleeding risk than vitamin K antagonists, especially risk of intracranial bleeding. Risk factors for bleeding are typically the same for old and new anticoagulants. Old age, renal dysfunction and concomitant antiplatelet agents seem to be recurring risk factors. Adequate supportive care and temporary removal of all antithrombotic agents constitute the basis for management of serious bleeding complications. With the exception of vitamin K (for vitamin K antagonists) and protamine (for heparin) the same array of prohemostatic agents--unactivated or activated prothrombin complex concentrate, and activated factor VIIa--have been tried for almost all anticocoagulants in different models, and for some agents also in patients, with varying success. Hemodialysis can reduce the level of dabigatran efficiently and activated charcoal may be used for very recent oral ingestion of lipophilic agents. In view of the shorter half life of the new agents compared to warfarin the need for reversal agents may be less critical. Nevertheless, highly specific reversal agents for the thrombin- and factor Xa-inhibitors are under development and might be available within two years.

Rivaroxaban: a review of its use in the treatment of deep vein thrombosis or pulmonary embolism and the prevention of recurrent venous thromboembolism

Rivaroxaban (Xarelto(®)), an oral direct factor Xa inhibitor, is approved for the initial treatment of deep vein thrombosis (DVT) and pulmonary embolism (PE), as well as the prevention of recurrent DVT and PE. It is administered at a fixed oral dose and does not require routine coagulation monitoring. In the EINSTEIN-DVT and EINSTEIN-PE trials, in over 8,000 patients with DVT and/or PE, a single-drug approach with rivaroxaban was shown to be noninferior to standard therapy consisting of subcutaneous enoxaparin sodium overlapping with and followed by an oral dose-adjusted vitamin K antagonist (enoxaparin-VKA) with regard to the incidence of symptomatic recurrent venous thromboembolism (VTE) after 3, 6 or 12 months of treatment. Rivaroxaban was generally well tolerated in patients with DVT or PE, with no significant between-group differences in clinically relevant bleeding between the rivaroxaban and enoxaparin-VKA groups. Notably, rivaroxaban was associated with a significantly lower rate of major bleeding compared with enoxaparin-VKA when EINSTEIN-DVT and EINSTEIN-PE data were pooled. Pharmacoeconomic analyses indicated that rivaroxaban may be a cost-effective alternative to enoxaparin-VKA for the treatment of DVT or PE and prevention of recurrent VTE. Extended prophylaxis with rivaroxaban reduced the incidence of symptomatic recurrent VTE to a greater extent than placebo in the EINSTEIN-Extension trial, but was associated with a non-significant increase in the risk of clinically relevant bleeding compared with placebo. In conclusion, rivaroxaban is a reasonable alternative to standard therapy for the treatment of DVT and PE, and as extended thromboprophylaxis.

Rivaroxaban and hemostasis in emergency care

Rivaroxaban is an oral, direct Factor Xa inhibitor, approved for the prevention and treatment of several thromboembolic disorders. Rivaroxaban does not require routine coagulation monitoring and has a short half-life. However, confirmation of rivaroxaban levels may be required in circumstances such as life-threatening bleeding or perioperative management. Here, we explore the management strategies in patients receiving rivaroxaban who have a bleeding emergency or require emergency surgery. Rivaroxaban plasma concentrations can be assessed quantitatively using anti-Factor Xa chromogenic assays, or qualitatively using prothrombin time assays (using rivaroxaban-sensitive reagents). In patients receiving long-term rivaroxaban therapy who require elective surgery, discontinuation of rivaroxaban 20–30 hours beforehand is normally sufficient to minimize bleeding risk. For emergency surgery, we advise against prophylactic use of hemostatic blood products, even with high rivaroxaban concentrations. Temporary rivaroxaban discontinuation is recommended if minor bleeding occurs; for severe bleeding, rivaroxaban withdrawal may be necessary, along with compression or appropriate surgical treatment. Supportive measures such as blood product administration might be beneficial. Life-threatening bleeding demands comprehensive hemostasis management, including potential use of agents such as prothrombin complex concentrate. Patients taking rivaroxaban who require emergency care for bleeding or surgery can be managed using established protocols and individualized assessment.

Assessment of anticoagulation intensity and management of bleeding with old and new oral anticoagulants

Warfarin is effective for the prevention and treatment of thromboembolism but produces variable anticoagulant effects and requires routine monitoring of the international normalized ratio (INR) to optimize the balance between efficacy and safety. The new oral anticoagulants (NOACs) have a more predictable anticoagulant effect and were recently demonstrated to be at least as efficacious and safe as warfarin despite being administered in fixed doses without routine coagulation monitoring. Specific laboratory tests have been developed to measure the anticoagulant effect of the NOACs but are not yet widely available, and the relation between drug levels and both coagulation test results and outcomes is uncertain. It remains to be demonstrated whether adjustment of the dose of NOACs, according to the results of laboratory testing, may lead to even greater efficacy and safety. The principles of bleeding management in patients treated with NOACs compared with patients receiving warfarin are similar. Most patients can be safely managed by interrupting drug treatment, performing local measures to stem the bleeding, and providing transfusion support as required. In patients with major or life-threatening bleeding and those requiring surgery, the anticoagulant effects of warfarin can be reversed using oral or intravenous vitamin K, fresh frozen plasma (FFP), and prothrombin complex concentrates (PCCs). Specific antidotes are under development for the NOACs but are not yet approved for clinical use. PCCs and recombinant factor VIIa may improve hemostasis in patients in whom bleeding develops during treatment with a NOAC, but their efficacy is unproven.

Novel antiplatelet and anticoagulant agents in the cardiac care unit

This article reviews the pivotal studies of several novel antiplatelet (prasugrel and ticagrelor) and anticoagulant (dabigatran, rivaroxaban, and apixaban) agents. The clinical use of these drugs in cardiac intensive care is discussed, focusing on the management of acute coronary syndromes, ischemic stroke, atrial fibrillation, and venous thromboembolism.