Albumin and bleed risk in rivaroxaban treated patients

Rivaroxaban for Thromboembolism Prophylaxis in Patients with Nephrotic Syndrome: A Single-Arm, Prospective Study

Introduction

Thromboembolism is a recognized complication of nephrotic syndrome (NS). Evidence supporting the use of rivaroxaban to prevent NS-related thrombosis is limited and controversial. This study aimed to explore the impact of NS on rivaroxaban pharmacokinetics and to collect observational data on the efficacy and safety of rivaroxaban as primary thromboprophylaxis in patients with NS.

Methods

This prospective study analyzed 141 patients with NS who received rivaroxaban (10 mg/day) for thromboprophylaxis. High-performance liquid chromatography-tandem mass spectrometry was used to measure the trough and peak plasma concentrations (Ctrough and Cmax) of rivaroxaban. The influence of clinical and genetic factors on these concentrations was examined using multivariate logistic regression.

Results

The median Cmax and Ctrough were 68.5 ng/mL (interquartile range [IQR], 31.7-105.5 ng/mL) and 4.4 ng/mL (IQR, 1.2-11.9 ng/mL), respectively. The incidence of thromboembolic events (TEs) was 12.8%, while that of bleeding events was 14.2%, although all were classified as minor. Albumin level was the most significant factor affecting Cmax (ρ = 0.55; p < 0.001) and was also significantly associated with TEs (0.81; 0.71-0.91 per 1.0 g/dL increase; p = 0.001) and bleeding risks (1.11; 1.03-1.19 per 1.0 g/dL increase; p = 0.008). Single nucleotide polymorphisms in the ABCB1 gene significantly influenced Ctrough but were not associated with clinical outcomes.

Conclusion

Hypoalbuminemia significantly affects the pharmacokinetics of rivaroxaban in NS patients. A dose-adjustment strategy based on rivaroxaban concentrations, accounting for variable albumin levels, may improve the safety and efficacy of thromboprophylaxis in this population.

Differential effects of FcRn antagonists on the subcellular trafficking of FcRn and albumin

The homeostasis of IgG is maintained by the neonatal Fc receptor, FcRn. Consequently, antagonism of FcRn to reduce endogenous IgG levels is an emerging strategy for treating antibody-mediated autoimmune disorders using either FcRn-specific antibodies or an engineered Fc fragment. For certain FcRn-specific antibodies, this approach has resulted in reductions in the levels of serum albumin, the other major ligand transported by FcRn. Cellular and molecular analyses of a panel of FcRn antagonists have been carried out to elucidate the mechanisms leading to their differential effects on albumin homeostasis. These analyses have identified 2 processes underlying decreases in albumin levels during FcRn blockade: increased degradation of FcRn and competition between antagonist and albumin for FcRn binding. These findings have potential implications for the design of drugs to modulate FcRn function.

Comparison of bleeding and ischemic events with apixaban vs. rivaroxaban in triple antithrombotic therapy regimens

OBJECTIVE

To compare the risk of readmissions for major bleeding within one year between apixaban and rivaroxaban as a component of triple antithrombotic therapy.

METHODS

This study was a multicenter, retrospective cohort study conducted at two academic medical centers in the Western New York and New York City region between July 1, 2011 and September 25, 2019. Adult patients were included if they were diagnosed with atrial fibrillation or venous thromboembolism and discharged on new triple antithrombotic therapy. The primary outcome compared the rates of 1-year readmission for major bleeding between apixaban and rivaroxaban groups. Secondary outcomes included rate of ischemic outcomes. Time to event analysis was determined with a Kaplan-Meier plot and Cox proportional hazard ratios (HR).

RESULTS

A total of 378 patients were included in the study, 212 in the apixaban group and 166 in the rivaroxaban group. Within 1 year, readmission for major bleeding events occurred in six (2.8%) patients in the apixaban group and four (2.4%) patients in the rivaroxaban group ( P  = 1.000). After adjustment, the major bleeding event rate was not statistically significantly different between apixaban and rivaroxaban [adjusted hazard ratio (aHR) 0.68, 95% confidence interval (CI) 0.12-3.77; P  = 0.6624]. Higher albumin levels were identified to be protective against major bleeding related readmission events (aHR 0.18, 95% CI 0.05-0.63; P  = 0.0072). The ischemic outcome occurred in seven (3.3%) patients in the apixaban group and three (1.8%) in the rivaroxaban group ( P  = 0.7368).

CONCLUSION

Use of apixaban or rivaroxaban in a triple antithrombotic regimen was not associated with bleeding or ischemic outcomes.

Direct Oral FXa Inhibitors Binding to Human Serum Albumin: Spectroscopic, Calorimetric, and Computational Studies

Direct FXa inhibitors are an important class of bioactive molecules (rivaroxaban, apixaban, edoxaban, and betrixaban) applied for thromboprophylaxis in diverse cardiovascular pathologies. The interaction of active compounds with human serum albumin (HSA), the most abundant protein in blood plasma, is a key research area and provides crucial information about drugs' pharmacokinetics and pharmacodynamic properties. This research focuses on the study of the interactions between HSA and four commercially available direct oral FXa inhibitors, applying methodologies including steady-state and time-resolved fluorescence, isothermal titration calorimetry (ITC), and molecular dynamics. The HSA complexation of FXa inhibitors was found to occur via static quenching, and the complex formation in the ground states affects the fluorescence of HSA, with a moderate binding constant of 10⁴ M^-1. However, the ITC studies reported significantly different binding constants (10³ M^-1) compared with the results obtained through spectrophotometric methods. The suspected binding mode is supported by molecular dynamics simulations, where the predominant interactions were hydrogen bonds and hydrophobic interactions (mainly π-π stacking interactions between the phenyl ring of FXa inhibitors and the indole moiety of Trp214). Finally, the possible implications of the obtained results regarding pathologies such as hypoalbuminemia are briefly discussed.

Low serum albumin: A neglected predictor in patients with cardiovascular disease

Albumin, the most abundant circulating protein in blood, is an essential protein which binds and transports various drugs and substances, maintains the oncotic pressure of blood and influences the physiological function of the circulatory system. Albumin also has anti-inflammatory, antioxidant, and antithrombotic properties. Evidence supports albumin's role as a strong predictor of cardiovascular (CV) risk in several patient groups. Its protective role extends to those with coronary artery disease, heart failure, hypertension, atrial fibrillation, peripheral artery disease or ischemic stroke, as well as those undergoing revascularization procedures or with aortic stenosis undergoing transcatheter aortic valve replacement, and patients with congenital heart disease and/or endocarditis. Hypoalbuminemia is a strong prognosticator of increased all-cause and CV mortality according to several cohort studies and meta-analyses in hospitalized and non-hospitalized patients with or without comorbidities. Normalization of albumin levels before discharge lowers mortality risk, compared with hypoalbuminemia before discharge. Modified forms of albumin, such as ischemia modified albumin, also has prognostic value in patients with coronary or peripheral artery disease. When albumin is combined with other risk factors, such as uric acid or C-reactive protein, the prognostic value is enhanced. Although albumin supplementation may be a plausible approach, its efficacy has not been established and in patients with hypoalbuminemia, priority is focused on diagnosing and managing the underlying condition. The CV effects of hypoalbuminemia and relevant issues are considered in this review. Large cohort studies and meta-analyses are tabulated and the physiologic effects of albumin and the deleterious effects of low albumin are pictorially illustrated.

Clinical Significance of Serum Albumin and Implications of FcRn Inhibitor Treatment in IgG-Mediated Autoimmune Disorders

Serum albumin (SA), the most abundant soluble protein in the body, maintains plasma oncotic pressure and regulates the distribution of vascular fluid and has a range of other important functions. The goals of this review are to expand clinical knowledge regarding the functions of SA, elucidate effects of dysregulated SA concentration, and discuss the clinical relevance of hypoalbuminemia resulting from various diseases. We discuss potential repercussions of SA dysregulation on cholesterol levels, liver function, and other processes that rely on its homeostasis, as decreased SA concentration has been shown to be associated with increased risk for cardiovascular disease, hyperlipidemia, and mortality. We describe the anti-inflammatory and antioxidant properties of SA, as well as its ability to bind and transport a plethora of endogenous and exogenous molecules. SA is the primary serum protein involved in binding and transport of drugs and as such has the potential to affect, or be affected by, certain medications. Of current relevance are antibody-based inhibitors of the neonatal Fc receptor (FcRn), several of which are under clinical development to treat immunoglobulin G (IgG)-mediated autoimmune disorders; some have been shown to decrease SA concentration. FcRn acts as a homeostatic regulator of SA by rescuing it, as well as IgG, from intracellular degradation via a common cellular recycling mechanism. Greater clinical understanding of the multifunctional nature of SA and the potential clinical impact of decreased SA are needed; in particular, the potential for certain treatments to reduce SA concentration, which may affect efficacy and toxicity of medications and disease progression.

Risk factors for ecchymosis in patients receiving rivaroxaban for thromboprophylaxis after total knee arthroplasty: a retrospective cohort study

WHAT IS KNOWN AND OBJECTIVE

Ecchymosis of the limb is commonly seen after total knee arthroplasty (TKA) when using anticoagulants for thromboprophylaxis, but it is unknown which factors may predispose patients to an increased risk. The aim of this study was to evaluate risk factors for ecchymosis in patients receiving rivaroxaban after TKA.

METHODS

A retrospective, single-centre cohort analysis was conducted. The electronic medical records of patients admitted to the Department of Orthopedics during January 2018 to December 2019 and who received rivaroxaban 10 mg daily after TKA were reviewed for documentation of ecchymosis. Baseline demographics, laboratory values and surgical information were included for analysing their relationship with ecchymosis.

RESULTS AND DISCUSSION

A total of 227 patients were included in the study. Among them, 54 patients (23.8%) developed ecchymosis, and 173 did not. The ecchymosis group had a higher proportion of patients with a body weight >60 kg [83.33% vs. 50.00%, p = 0.0004] and hypertension [61.11% vs 41.46%, p = 0.0304]. The ecchymosis group also had a higher BMI [26.04 ± 2.71 kg/m² vs 24.52 ± 3.18 kg/m² , p = 0.0066] mean arterial pressure (MAP) recorded from post-operation day 1 to day 3 [105.21 mmHg vs 91.52 mmHg, p = 0.0003]. However, serum albumin concentrations before surgery [3.85 g/dL vs. 4.20 g/dL, p = 0.0225] and on post-operation day 3 [3.50 g/dL vs. 3.91 g/dL, p = 0.0370] were lower in the ecchymosis group. Serum haemoglobin on post-operation day 3 was also lower [10.07 g/dL vs. 11.57 g/dL, p = 0.0459]. Five risk factors for ecchymosis were identified by binary logistic regression: mean MAP (from POD1 to POD3) (OR=2.901, 95% CI: 2.522-3.293, p < 0.001), BMI (OR=2.513, 95% CI: 1.929-3.011, p < 0.001), history of hypertension (OR=2.661, 95% CI: 1.272-4.535, p = 0.032), post-surgery serum albumin level (OR=0.848, 95% CI: 0.735-0.977, p = 0.023) and post-surgery serum haemoglobin level (OR=0.943; 95% CI: 0.898-0.990, p = 0.018).

WHAT IS NEW AND CONCLUSION

The present analyses identified that BMI, history of hypertension, mean MAP (POD1 to POD3), post-surgery serum albumin level and post-surgery serum haemoglobin level were independent risk factors for rivaroxaban-related ecchymosis in patients who underwent TKA. These factors should be considered and optimized before starting rivaroxaban therapy.