Effect of polypharmacy on bleeding with rivaroxaban versus vitamin K antagonist for treatment of venous thromboembolism.

BACKGROUND: Polypharmacy, including use of inhibitors of CYP3A4 and P-glycoprotein (P-gp), is common in patients with venous thromboembolism (VTE) and is associated with increased bleeding. METHODS: In 8246 patients included in the EINSTEIN-VTE studies for acute VTE, we evaluated the effect of polypharmacy on bleeding and on the relative differences between rivaroxaban and enoxaparin/vitamin K antagonist (VKA). We assessed the incidence of clinically relevant bleeding (major and clinically relevant nonmajor bleeding) by number of comedications (none, 1-3, ≥4) at baseline, and by use of CYP3A4 and/or P-gp inhibitors. Interaction between rivaroxaban versus enoxaparin/VKA and comedication was assessed by Cox regression analysis with pinteraction estimates. RESULTS: With increasing number of comedications, the incidence of clinically relevant bleeding rose from 5.7% to 13.3% in rivaroxaban recipients and from 9.1% to 11.1% in enoxaparin/VKA recipients. Whereas rivaroxaban was associated with a reduced bleeding risk compared with enoxaparin/VKA in patients without comedication (hazard ratio [HR] 0.6, 95% confidence interval [CI] 0.4-0.9), the risk was similar in patients with ≥4 comedications (HR 1.2, 95% CI 0.97-1.5, pinteraction .002). Use of CYP3A4 and/or P-gp inhibitors was associated with a doubled bleeding risk compared with no use, without a difference between rivaroxaban and enoxaparin/VKA. CONCLUSION: We conclude that fixed-dose rivaroxaban as compared with enoxaparin followed by dose-adjusted VKA is not associated with an increased bleeding risk in patients with VTE administered polypharmacy in general and CYP3A4 and/or P-gp inhibitors specifically. This implies that the observed increased bleeding risks with polypharmacy and use of CYP3A4 and/or P-gp inhibitors are likely explained by comorbidities and frailty, and not by pharmacokinetic interactions.

Synergy of Dual Pathway Inhibition in Chronic Cardiovascular Disease.

Although acetylsalicylic acid is of proven benefit for secondary prevention in patients with cardiovascular disease, the risk of recurrent ischemic events remains high. Intensification of antithrombotic therapy with more potent antiplatelet drugs, dual antiplatelet therapy, or vitamin K antagonists further reduces the risk of major adverse cardiovascular events compared with acetylsalicylic acid alone but increases the risk of bleeding without reducing mortality. In patients with prior coronary artery disease or peripheral arterial disease the COMPASS (Cardiovascular Outcomes for People Using Anticoagulation Strategies) trial revealed that compared with acetylsalicylic acid alone, dual pathway inhibition with low-dose rivaroxaban (2.5 mg twice-daily), an oral factor Xa inhibitor, plus acetylsalicylic acid reduced major adverse cardiovascular event by 24%, major adverse limb events by 47%, and mortality by 18%. Major bleeding was increased by 70%, but there was no increase in fatal or intracranial bleeding. This article (1) reviews the results of the COMPASS trial, (2) explains why dual pathway inhibition is superior to antiplatelet or anticoagulant therapy alone, (3) compares the results with rivaroxaban plus aspirin with those with other antithrombotic regimens, and (4) provides insight into how best to apply the COMPASS results into practice.

The Perioperative Anticoagulant Use for Surgery Evaluation (PAUSE) Study for Patients on a Direct Oral Anticoagulant Who Need an Elective Surgery or Procedure: Design and Rationale.

Background The perioperative management of patients who take a direct oral anticoagulant (DOAC) for atrial fibrillation and require treatment interruption for an elective surgery/procedure is a common clinical scenario for which best practices are uncertain. The Perioperative Anticoagulant Use for Surgery Evaluation (PAUSE) study is designed to address this unmet clinical need. We discuss the rationale for the PAUSE design and analysis plan as well as the rationale supporting the perioperative DOAC protocol. Methods PAUSE is a prospective study with three parallel cohorts, one for each DOAC, to assess a standardized but patient-specific perioperative management protocol for DOAC-treated patients with atrial fibrillation. The perioperative protocol accounts for DOAC type, patient's renal function and surgery/procedure-related bleeding risk. The primary study aim is to demonstrate the safety of the PAUSE protocol for the perioperative management of each DOAC. The secondary aim is to determine the effect of the pre-procedure interruption on residual anticoagulation when measured by the dilute thrombin time for dabigatran and anti-factor Xa levels for rivaroxaban and apixaban. The study hypothesis is that the perioperative management protocol for each DOAC is safe for patient care, defined by expected risks for major bleeding of 1% (80% power to exclude 2%), and for arterial thromboembolism of 0.5% (80% power to exclude 1.5%) in each DOAC group. Conclusion The PAUSE study has the potential to establish a standard-of-care approach for the perioperative management of DOAC-treated patients. The PAUSE management protocol is designed to be easily applied in clinical practice, as it is standardized and also patient specific.

Pharmacokinetics of dabigatran etexilate and rivaroxaban in patients with short bowel syndrome requiring parenteral nutrition: The PDER PAN study.

BACKGROUND AND AIMS: Patients on parenteral nutrition for short bowel syndrome (SBS) have a high risk of thrombotic complications and are often treated with parenteral anticoagulation. Direct oral anticoagulants are absorbed proximally in the digestive tract and may represent alternative regimens in selected SBS patients. In our pilot study, we provided pharmacokinetics parameters of dabigatran etexilate and rivaroxaban in this setting and compared peak (Cmax), trough (Ctrough) concentrations, and areas-under-the-concentration-time-curve (AUC0-t) to reference values retrieved from phase I-III studies. METHODS: We enrolled 6 adults with a remaining small bowel length≤200cm, normal renal/hepatic function, and intact stomach. In our crossover study, patients were exposed to twice-daily dabigatran etexilate 150mg and once-daily rivaroxaban 20mg. RESULTS: After 5days of dabigatran dosing, Ctrough and Cmax geometric means were 39µg/L (90% CI: 23-66) and 88µg/L (90% CI: 56-137), respectively; AUC0-12h was 958µg∗h/L (90% CI: 635-1445). After 5days of rivaroxaban dosing, Ctrough and Cmax geometric means were 9µg/L (90% CI: 1-71) and 167µg/L (90% CI: 102-276), respectively; AUC0-24h was 1720µg∗h/L (90% CI: 899-3300). Absorption was negligible in one patient with ultra-short (~15cm) bowel. For dabigatran, Cmax ratio was 0.57 (SD 0.33) and Ctrough ratio was 0.35 (SD 0.44). For rivaroxaban, the mean observed-to-reference ratios AUC0-24h and Cmax ratios were 0.73 (SD 0.32) and 0.76 (SD 0.34), respectively. CONCLUSIONS: While in SBS patients there is some absorption of the oral anticoagulants dabigatran etexilate and rivaroxaban, it appears to be lower than reference values. Plasma drug levels showed significant inter-individual variability.

Anticoagulants for the prevention and treatment of catheter-related thrombosis in adults and children on parenteral nutrition: a systematic review and critical appraisal.

BACKGROUND: Patients on parenteral nutrition require a central venous access and are at risk of catheter-related thrombosis, pulmonary embolism, and vena cava syndrome. Parenteral nutrition guidelines suggest anticoagulation for the primary prevention of catheter-related thrombosis during long-term parenteral nutrition. We conducted a systematic review of the efficacy, safety and feasibility of anticoagulant use for preventing and treating catheter-related thrombosis during parenteral nutrition. MATERIALS AND METHODS: We searched for interventional and observational studies on adults and children receiving systemic anticoagulants during either short- or long-term parenteral nutrition delivered via central venous access. Primary outcomes were: objectively-confirmed catheter-related thrombosis, pulmonary embolism and bleeding. Secondary outcomes were: heparin-induced thrombocytopenia, prevalence of anticoagulation, and quality of International Normalised Ratio management in vitamin K antagonist-treated patients. RESULTS: We identified 1,199 studies, of which 23 were included. Seven interventional studies of short-term parenteral nutrition (adult population, n=5) were classified as low-quality: in those, intravenous unfractionated heparin did not prevent catheter-related thrombosis if compared to saline. No interventional studies were conducted in patients on long-term parenteral nutrition. Observational data were sparse, rarely focusing on anticoagulation, and overall of low quality. The reported use of anticoagulants was between 22 and 66% in recent multicentre cohorts. DISCUSSION: The amount and quality of data in this area are very suboptimal: most studies are outdated and involved heterogeneous populations. Currently, there is insufficient evidence to allow conclusions to be reached regarding the efficacy and safety of anticoagulants in this setting.

New oral anticoagulants in elderly patients.

The new oral anticoagulants (NOACs) dabigatran etexilate, rivaroxaban, and apixaban have been extensively studied for prevention and treatment of venous thromboembolic disease and for stroke prevention in atrial fibrillation. Elderly patients have the highest incidence of thrombotic complications but also have the highest risk of anticoagulant associated bleeding. In this review we critically examine the balance between risks and benefits of NOACs compared with vitamin K antagonists in elderly patients enrolled in phase 3 randomized controlled trials for the management of venous thrombosis and stroke prevention in atrial fibrillation. Results show that the favourable balance between risks and benefits of NOACs is preserved in the elderly population.

Translational success stories: development of direct thrombin inhibitors.

Anticoagulants are the cornerstone of therapy for conditions associated with arterial and venous thrombosis. Direct thrombin inhibitors (DTIs) are anticoagulants that bind to thrombin and block its enzymatic activity. The bivalent parenteral DTIs hirudin and bivalirudin were based on the observation that the salivary extracts of medicinal leeches prevented blood from clotting. Key events that facilitated the subsequent development of small molecule active site inhibitors, such as argatroban, were the observation that fibrinopeptide A had antithrombotic properties and determination of the crystal structure of thrombin. Hirudin and argatroban have found their niche for the treatment of patients with heparin-induced thrombocytopenia, whereas bivalirudin is approved as an alternative to heparin for patients undergoing percutaneous coronary intervention. The development of orally active direct thrombin inhibitors was challenging because of the need to convert water-soluble, poorly absorbable, active site inhibitors into fat-soluble prodrugs that were then transformed back to the active drug after intestinal absorption. Dabigatran etexilate was the first new oral anticoagulant to be approved for long-term anticoagulant treatment in 6 decades. This Review highlights the development of DTIs as a translational success story; an example in which the combination of scientific ingenuity, structure-based design, and rigorous clinical trials has created a new class of anticoagulants that has improved patient care.