Pharmacokinetics and pharmacodynamics of oral anticoagulants used in atrial fibrillation

Advancements of direct oral anticoagulants in cirrhotic individuals with portal vein thrombosis

Individuals with cirrhosis maintain a delicate balance between pro- and anticoagulation, which can lead to a state of hypercoagulability. This hypercoagulable condition not only exacerbates liver fibrosis but also increases the risk of venous thrombosis, particularly portal vein thrombosis (PVT). PVT has detrimental effects on liver function, complicates the success of liver transplantation, and negatively impacts the survival rate of patients with cirrhosis. Currently, multiple studies have confirmed that individuals with cirrhosis responded well to treatment with novel direct oral anticoagulants (DOACs), showing both safety and efficacy. Furthermore, the use of DOACs as a preventive measure in patients with cirrhosis following surgery has been shown to lower the occurrence of portal vein thrombosis and postpone the progression of liver fibrosis.

A mini review on the regulation of coagulation homeostasis through interfering with vitamin K-dependent coagulation/anticoagulation factors

Coagulation disorders, such as excessive bleeding or thrombosis, present significant health challenges. Vitamin K-dependent proteins (VKDPs), including coagulation and anticoagulation factors, are essential for maintaining the coagulation homeostasis due to their key roles in the coagulation cascade. Therefore, VKDPs have become significant targets for regulating coagulation homeostasis, and various strategies have been developed, primarily including small molecule drugs and nanomaterials. This review presents the summary of these strategies, focusing on the mechanisms, effectiveness and limitations. It first discusses the pivotal role of VKDPs in the coagulation cascade, followed by an in-depth analysis of how small molecule drugs and nanomaterials to regulate hemostasis through interfering with VKDPs. Furthermore, this review addresses the challenges faced in the current approaches and potential future research directions. We hope this review will contribute to advancing the development of novel methods for modulating coagulation homeostasis through VKDP interference.

Anticoagulation reversal (vitamin K, prothrombin complex concentrates, idarucizumab, andexanet-α, protamine)

Bleeding events are common in patients prescribed anticoagulants and can have devastating consequences. Several specific and nonspecific agents have been developed to reverse the effects of anticoagulant drugs or toxins. Vitamin K, as the oldest of these antidotes, specifically counteracts the effects of pharmaceuticals and rodenticides designed to deplete stores of vitamin K-dependent factors. In cases of life-threatening bleeding, the addition of prothrombin complex concentrates (PCCs) allows for the immediate replacement of coagulation factors. While the use of PCCs has been extended to the non-specific reversal of the effects of newer direct oral anticoagulants, the specific agents idarucizumab, targeting dabigatran and andexanet-α, binding factor Xa inhibitors, have recently been developed and are being preferentially recommended by most guidelines. However, despite having rapid effects on correcting coagulopathy, there is to date a lack of robust evidence establishing the clear superiority of direct oral anticoagulant-specific reversal agents over PCCs in terms of haemostatic efficacy, safety or mortality. For andexanet-α, a potential signal of increased thromboembolic risks, comparatively high costs and low availability might also limit its use, even though emerging evidence appears to bolster its role in intracranial haemorrhage. Protamine is the specific agent for the reversal of unfractionated heparin anticoagulation used mainly in cardiovascular surgery. It is much less effective for low molecular weight heparin fragments and is usually reserved for cases with life-threatening bleeding.

Prodrug Approach as a Strategy to Enhance Drug Permeability

Absorption and permeability are critical physicochemical parameters that must be balanced to achieve optimal drug uptake. These key factors are closely linked to the maximum absorbable dose required to provide appropriate plasma levels of drugs. Among the various strategies employed to enhance drug solubility and permeability, prodrug design stands out as a highly effective and versatile approach for improving physicochemical properties and enabling the optimization of biopharmaceutical and pharmacokinetic parameters while mitigating adverse effects. Prodrugs are compounds with reduced or no activity that, through bio-reversible chemical or enzymatic processes, release an active parental drug. The application of this technology has led to significant advancements in drug optimization during the design phase, and it offers broad potential for further development. Notably, approximately 13% of the drugs approved by the U.S. Food and Drug Administration (FDA) between 2012 and 2022 were prodrugs. In this review article, we will explore the application of prodrug strategies to enhance permeability, describing examples of market drugs. We also describe the use of the prodrug approach to optimize PROteolysis TArgeting Chimeras (PROTACs) permeability by using conjugation technologies. We will highlight some new technologies in prodrugs to enrich permeability properties, contributing to developing new effective and safe prodrugs.

Tailoring oral anticoagulant treatment in the era of multi-drug therapies for PAH and CTEPH

The use of oral anticoagulants in the management of pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) presents distinct therapeutic challenges and benefits. In PAH, the benefits of oral anticoagulation are uncertain, with studies yielding mixed results on their efficacy and safety. Conversely, oral anticoagulants are a cornerstone in the treatment of CTEPH, where their use is consistently recommended to prevent recurrent thromboembolic events. The choice between vitamin K antagonists (VKAs) and direct oral anticoagulants (DOACs) remains a significant clinical question, as each type presents advantages and potential drawbacks. Furthermore, drug-drug interactions (DDIs) with concomitant PAH and CTEPH treatments complicate anticoagulant management, necessitating careful consideration of individual patient regimens. This review examines the current evidence on oral anticoagulant use in PAH and CTEPH and discusses the implications of DDIs within a context of multi-drug treatments, including targeted drugs in PAH.

Association Between Oral Anticoagulant Adherence and Serious Clinical Outcomes in Patients With Atrial Fibrillation: A Long-Term Retrospective Cohort Study

BACKGROUND

Patients with atrial fibrillation are frequently nonadherent to oral anticoagulants (OACs) prescribed for stroke and systemic embolism (SSE) prevention. We quantified the relationship between OAC adherence and atrial fibrillation clinical outcomes using methods not previously applied to this problem.

METHODS AND RESULTS

Retrospective observational cohort study of incident cases of atrial fibrillation from population-based administrative data over 23 years. The exposure of interest was proportion of days covered during 90 days before an event or end of follow-up. Cox proportional hazard models were used to evaluate time to first SSE and the composite of SSE, transient ischemic attack, or death and several secondary outcomes. A total of 44 172 patients were included with median follow-up of 6.7 years. For direct OACs (DOACs), each 10% decrease in adherence was associated with a 14% increased hazard of SSE and 5% increased hazard of SSE, transient ischemic attack, or death. For vitamin K antagonist (VKA) the corresponding increase in SSE hazard was 3%. Receiving DOAC or VKA was associated with primary outcome hazard reduction across most the proportion of days covered spectrum. Differences between VKA and DOAC were statistically significant for all efficacy outcomes and at most adherence levels.

CONCLUSIONS

Even small reductions in OAC adherence in patients with atrial fibrillation were associated with significant increases in risk of stroke, with greater magnitudes for DOAC than VKA. DOAC recipients may be more vulnerable than VKA recipients to increased risk of stroke and death even with small reductions in adherence. The worsening efficacy outcomes associated with decreasing adherence occurred without the benefit of major bleeding reduction.

Beyond Anticoagulation: A Comprehensive Review of Non-Vitamin K Oral Anticoagulants (NOACs) in Inflammation and Protease-Activated Receptor Signaling

Non-vitamin K oral anticoagulants (NOACs) have revolutionized anticoagulant therapy, offering improved safety and efficacy over traditional agents like warfarin. This review comprehensively examines the dual roles of NOACs-apixaban, rivaroxaban, edoxaban, and dabigatran-not only as anticoagulants, but also as modulators of inflammation via protease-activated receptor (PAR) signaling. We highlight the unique pharmacotherapeutic properties of each NOAC, supported by key clinical trials demonstrating their effectiveness in preventing thromboembolic events. Beyond their established anticoagulant roles, emerging research suggests that NOACs influence inflammation through PAR signaling pathways, implicating factors such as factor Xa (FXa) and thrombin in the modulation of inflammatory responses. This review synthesizes current evidence on the anti-inflammatory potential of NOACs, exploring their impact on inflammatory markers and conditions like atherosclerosis and diabetes. By delineating the mechanisms by which NOACs mediate anti-inflammatory effects, this work aims to expand their therapeutic utility, offering new perspectives for managing inflammatory diseases. Our findings underscore the broader clinical implications of NOACs, advocating for their consideration in therapeutic strategies aimed at addressing inflammation-related pathologies. This comprehensive synthesis not only enhances understanding of NOACs' multifaceted roles, but also paves the way for future research and clinical applications in inflammation and cardiovascular health.

Warfarin-A natural anticoagulant: A review of research trends for precision medication

BACKGROUND

Warfarin is a widely prescribed anticoagulant in the clinic. It has a more considerable individual variability, and many factors affect its variability. Mathematical models can quantify the quantitative impact of these factors on individual variability.

PURPOSE

The aim is to comprehensively analyze the advanced warfarin dosing algorithm based on pharmacometrics and machine learning models of personalized warfarin dosage.

METHODS

A bibliometric analysis of the literature retrieved from PubMed and Scopus was performed using VOSviewer. The relevant literature that reported the precise dosage of warfarin calculation was retrieved from the database. The multiple linear regression (MLR) algorithm was excluded because a recent systematic review that mainly reviewed this algorithm has been reported. The following terms of quantitative systems pharmacology, mechanistic model, physiologically based pharmacokinetic model, artificial intelligence, machine learning, pharmacokinetic, pharmacodynamic, pharmacokinetics, pharmacodynamics, and warfarin were added as MeSH Terms or appearing in Title/Abstract into query box of PubMed, then humans and English as filter were added to retrieve the literature.

RESULTS

Bibliometric analysis revealed important co-occuring MeShH and index keywords. Further, the United States, China, and the United Kingdom were among the top countries contributing in this domain. Some studies have established personalized warfarin dosage models using pharmacometrics and machine learning-based algorithms. There were 54 related studies, including 14 pharmacometric models, 31 artificial intelligence models, and 9 model evaluations. Each model has its advantages and disadvantages. The pharmacometric model contains biological or pharmacological mechanisms in structure. The process of pharmacometric model development is very time- and labor-intensive. Machine learning is a purely data-driven approach; its parameters are more mathematical and have less biological interpretation. However, it is faster, more efficient, and less time-consuming. Most published models of machine learning algorithms were established based on cross-sectional data sourced from the database.

CONCLUSION

Future research on personalized warfarin medication should focus on combining the advantages of machine learning and pharmacometrics algorithms to establish a more robust warfarin dosage algorithm. Randomized controlled trials should be performed to evaluate the established algorithm of warfarin dosage. Moreover, a more user-friendly and accessible warfarin precision medicine platform should be developed.

Kidney Function Decline and Serious Adverse Drug Reactions in Patients With CKD

RATIONALE & OBJECTIVE

Adverse drug reactions (ADRs) are common in patients with chronic kidney disease (CKD). The impact of kidney function decline on serious ADR risk has been poorly investigated. We comprehensively describe ADRs and assess the relationship between estimated glomerular filtration rate (eGFR) and serious ADR risk.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

3,033 participants in French Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN) cohort study, a nationwide sample of nephrology outpatients with moderate to advanced CKD.

PREDICTORS

Demographic and biological data (including eGFR), medication prescriptions.

OUTCOME

ADRs (preventable or not) were prospectively identified from hospital discharge reports, medical records, and patient interviews. Expert pharmacologists used validated tools to adjudicate ADRs.

ANALYTICAL APPROACH

Restricted cubic splines in fully adjusted cause-specific Cox proportional hazard models were used to evaluate the relationship between eGFR and the risk of serious ADRs (overall and by subtype).

RESULTS

During a median follow-up period of 4.7 years, 360 patients experienced 488 serious ADRs. Kidney and urinary disorders (n=170) and hemorrhage (n=170) accounted for 70% of serious ADRs. The most common medications classes were antithrombotics and renin-angiotensin system inhibitors. The majority of those serious ADRs were associated with hospitalization (n=467), with 32 directly or indirectly associated with death and 22 associated with a life-threatening event. More than 27% of the 488 serious ADRs were preventable or potentially preventable. The eGFR is a major risk factor for serious ADRs. The risk of acute kidney injury was 2.2% higher and risk of bleeding ADRs was 8% higher for each 1mL/min/1.73m2 lower baseline eGFR.

LIMITATIONS

The results cannot be extrapolated to patients who are not being treated by a nephrologist.

CONCLUSIONS

ADRs constitute a major cause of hospitalization in CKD patients for whom lower eGFR level is a major risk factor.

PLAIN-LANGUAGE SUMMARY

Patients with chronic kidney disease (CKD) have complex clinical presentations, take multiple medications, and often receive inappropriate prescriptions. Using data from a large, prospective CKD cohort, we found a high incidence of serious adverse drug reactions (ADRs). The 2 most common serious ADRs were drug-induced acute kidney injury and bleeding. A large proportion of serious ADRs required hospital admission, and 11% led to death or were life threatening. Lower kidney function was a major risk factor for serious ADRs. Many of these serious ADRs were determined to be partly preventable through greater adherence to prescription guidelines. This report enhances our understanding of the potential toxicity of drugs taken by patients with moderate to advanced CKD. It emphasizes the importance of monitoring kidney function when prescribing drugs, particularly for high-risk medications such as antithrombotic agents.

Pharmacokinetics and pharmacodynamics of direct oral anticoagulants

INTRODUCTION

Direct oral anticoagulants (DOACs) have overtaken vitamin K antagonists to become the most widely used method of anticoagulation for most indications. Their stable and predictable pharmacokinetics combined with relatively simple dosing, and the absence of routine monitoring has made them an attractive proposition for healthcare providers. Despite the benefits of DOACs as a class, important differences exist between individual DOAC drugs in respect of their pharmacokinetic and pharmacodynamic profiles with implications for dosing and reversal in cases of major bleeding.

AREAS COVERED

This review summarizes the state of knowledge relating to the pharmacokinetics of dabigatran (factor IIa/thrombin inhibitor) and apixaban, edoxaban and rivaroxaban (factor Xa) inhibitors. We focus on pharmacokinetic differences between the drugs which may have clinically significant implications.

EXPERT OPINION

Patient-centered care necessitates a careful consideration of the pharmacokinetic and pharmacodynamic differences between DOACs, and how these relate to individual patient circumstances. Prescribers should be aware of the potential for pharmacokinetic drug interactions with DOACs which may influence prescribing decisions in patients with multiple comorbidities. In order to give an appropriate dose of DOAC drugs, accurate estimation of renal function using the Cockcroft-Gault formula using actual body weight is necessary. An increasing body of evidence supports the use of DOACs in patients who are obese, and this is becoming more routine in clinical practice.

Comparison of phenprocoumon with direct oral anticoagulants in catheter ablation of atrial fibrillation

Aims

In patients undergoing catheter ablation for atrial fibrillation (AF), direct oral anticoagulants (DOACs) are as effective and safe as the vitamin K antagonist (VKA) warfarin. Phenprocoumon has a different pharmacokinetic profile compared with warfarin and is the most used VKA in Germany. The aim of the study was to compare DOAC with phenprocoumon.

Methods and results

In this retrospective single-centre cohort study, 1735 patients who underwent 2219 consecutive catheter ablations for AF between January 2011 and May 2017 were included. All patients were in-hospital for at least 48 h after catheter ablation. The primary outcome was defined as peri-procedural thrombo-embolic events. The secondary outcome was any bleeding according to the International Society on Thrombosis and Haemostasis (ISTH). The mean age of the patients was 63.3 years. Phenprocoumon was prescribed in 929 (42%) of the cases, and in 697 (31%) dabigatran, 399 (18%) rivaroxaban, and 194 (9%) apixaban. During hospitalization, 37 (1.6%) thrombo-embolic events occurred, including 23 transient ischaemic attacks (TIAs). Compared with the use of phenoprocoumon, the use of DOAC was significantly associated with a lower thrombo-embolic risk [16 (1.2%) vs. 21 (2.2%), odds ratio (OR)], 0.5 [95% confidence interval (CI) 0.2-0.9], P = 0.04. No statistically significant association with bleeding risk was observed [phenprocomoun: 122 (13%); DOAC: 163 (12.6%); OR 0.9 (95% CI 0.7-1.2); P = 0.70]. Interruption of oral anticoagulation (OAC) was associated with an increased risk for thrombo-embolic complications [OR 2.2 (1.1-4.3); P = 0.031], and bleeding [OR 2.5 (95% CI 1.8-3.2), P = 0.001].

Conclusion

In patients undergoing catheter ablation for AF, the use of DOAC was associated with a reduced risk of thrombo-embolic events compared with phenprocoumon. Non-interrupted oral anticoagulation (OAC) therapy was associated with a reduced risk of peri-procedural thrombo-embolic and any bleeding complications.

Direct Oral Anticoagulants: An Updated Systematic Review of Their Clinical Pharmacology and Clinical Effectiveness and Safety in Patients With Nonvalvular Atrial Fibrillation

Direct oral anticoagulants have been an increasingly used class of drugs in the setting of nonvalvular atrial fibrillation, defying vitamin K antagonists' monopoly when it comes to anticoagulation due to its several limitations. Direct oral anticoagulants (DOACs) have entered the market as a noninferior and safer option in comparison with vitamin K antagonists, as their respective phase III clinical trials proved. The aim of this article was to update and summarize data on their clinical pharmacology and to review real-world data to know their comparative effectiveness and safety. We performed a systematic review using PubMed, Google Scholar, Embase, and Web of Science as search engines. Regarding pharmacodynamics, there were no substantial changes reported from their original profile. There were many advances in the knowledge about clinical pharmacokinetics of DOACs that have had a direct impact on their clinical use, mainly related to drug-drug interactions. In a real-world setting, DOACs have shown to be noninferior in preventing thromboembolic events compared to vitamin K antagonists. In regards to safety, DOACs have shown a lower bleeding risk relative to warfarin. Comparison between DOACs has demonstrated rivaroxaban to have the highest bleeding risk. Overall, the evidence gathered showed few changes from the original data presented in phase III clinical trials, concluding that their real-world use coincides greatly with them.

Genetic variations in relation to bleeding and pharmacodynamics of dabigatran in Chinese patients with nonvalvular atrial fibrillation: A nationwide multicentre prospective cohort study

INTRODUCTION

To identify the potential factors responsible for the individual variability of dabigatran, we investigated the genetic variations associated with clinical outcomes and pharmacodynamics (PD) in Chinese patients with nonvalvular atrial fibrillation (NVAF).

MATERIALS AND METHODS

Chinese patients with NVAF taking dabigatran etexilate with therapeutic doses were enrolled. The primary (bleeding events) and secondary (thromboembolic and major adverse cardiac events) outcomes for a 2-year follow-up were evaluated. Peak and trough PD parameters (anti-FIIa activity, activated partial thromboplastin time and prothrombin time) were detected. Whole-exome sequencing, genome-wide sequencing and candidate gene association analyses were performed.

RESULTS

There were 170 patients with NVAF treated with dabigatran (110 mg twice daily) who were finally included. Two single-nucleotide polymorphisms (SNPs) were significantly related with bleeding, which include UBASH3B rs2276408 (odds ratio [OR] = 8.79, 95% confidence interval [CI]: 2.99-25.83, p = 7.77 × 10-5 at sixth month visit) and FBN2 rs3805625 (OR = 8.29, 95% CI: 2.87-23.89, p = 9.08 × 10-5 at 12th month visit), as well as with increased trends at other visits (p < .05). Furthermore, minor allele carriers of 16 new SNPs increased PD levels, and those of one new SNP decreased PD values (p < 1.0 × 10-5 ). Lastly, 33 new SNPs were found to be associated with bleeding and PD among 14 candidate genes. Unfortunately, the low number of secondary outcomes precluded further association analyses.

CONCLUSIONS

Genetic variations indeed affected bleeding and PD in Chinese patients with NVAF treated with dabigatran. The functions of these suggestive genes and SNPs might further be explored and verified in more in vivo and in vitro investigations.

Predicting drug-drug interactions with physiologically based pharmacokinetic/pharmacodynamic modelling and optimal dosing of apixaban and rivaroxaban with dronedarone co-administration

BACKGROUND

The concurrent administration of dronedarone and oral anti-coagulants is common because both are used in managing atrial fibrillation (AF). Dronedarone is a moderate inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme and P-glycoprotein (P-gp). Apixaban and rivaroxaban are P-gp and CYP3A4 substrates. This study aims to investigate the impact of exposure and bleeding risk of apixaban or rivaroxaban when co-administered with dronedarone using physiologically based pharmacokinetic/pharmacodynamic analysis.

METHODS

Modeling and simulation were conducted using Simcyp® Simulator. The parameters required for dronedarone modeling were collected from the literature. The developed dronedarone physiologically based pharmacokinetic (PBPK) model was verified using reported drug-drug interactions (DDIs) between dronedarone and CYP3A4 and P-gp substrates. The model was applied to evaluate the DDI potential of dronedarone on the exposure of apixaban 5 mg every 12 h or rivaroxaban 20 mg every 24 h in geriatric and renally impaired populations. DDIs precipitating major bleeding risks were assessed using exposure-response analyses derived from literature.

RESULTS

The model accurately described the pharmacokinetics of orally administered dronedarone in healthy subjects and accurately predicted DDIs between dronedarone and four CYP3A4 and P-gp substrates with fold errors <1.5. Dronedarone co-administration led to a 1.29 (90 % confidence interval (CI): 1.14-1.50) to 1.31 (90 % CI: 1.12-1.46)-fold increase in the area under concentration-time curve for rivaroxaban and 1.33 (90 % CI: 1.15-1.68) to 1.46 (90 % CI: 1.24-1.92)-fold increase for apixaban. The PD model indicated that dronedarone co-administration might potentiate the mean major bleeding risk of apixaban with a 1.45 to 1.95-fold increase. However, the mean major bleeding risk of rivaroxaban was increased by <1.5-fold in patients with normal or impaired renal function.

CONCLUSIONS

Dronedarone co-administration increased the exposure of rivaroxaban and apixaban and might potentiate major bleeding risks. Reduced apixaban and rivaroxaban dosing regimens are recommended when dronedarone is co-administered to patients with AF.

Hemopericardium in the Setting of Direct Oral Anticoagulant Use: An Updated Systematic Review

BACKGROUND

Spontaneous hemopericardium, associated with direct oral anticoagulant (DOAC) use, is one of the uncommon complications with high morbidity that has not been extensively studied We aimed to determine demographic characteristics, clinical features, lab evaluation, management, and outcomes of the studies focusing on hemopericardium as a DOAC use.

METHODS

PubMed, Web of Science, Google Scholar, and CINAHL databases were searched for relevant articles using MeSH key-words and imported into referencing/review software. The data regarding demographics, clinical characteristics, cardiac investigations, and management were analyzed in IBM Statistics SPSS 21. t-Test and Chi-square test were used. A P score of <0.05 was considered statistically significant.

RESULTS

After literature search, a total of 41 articles were selected for analysis. The mean age of the patients was 70.09 ± 11.06 years (p < 0.05); the majority of them were males (58.5%). Most of the patients presented with shortness of breath (75.2%) and had more than 3 co-morbid conditions (43.9%). The most frequently used anticoagulant was rivaroxaban (15/41; 36.6%); the common indication being arrhythmia (78.0%). CYP4503A4/P-Gp inhibitors (22.2%) were commonly used by the patients. Majority of the cases had a favorable outcome (95.1%). Pericardial tamponade was noted in 31/41 cases. Pericardiocentesis was performed in 37/41 cases.

CONCLUSIONS

Hemopericardium from DOAC use has a favorable outcome but requires urgent pericardiocentesis. However, long term mortality, monitoring of DOAC activity, and drug-drug interactions have not been widely studied.

SLC4A4, FRAS1, and SULT1A1 Genetic Variations Associated With Dabigatran Metabolism in a Healthy Chinese Population

Background: The purpose of this study was to identify genetic variations associated with the metabolism of dabigatran in healthy Chinese subjects, with particular focus given to pharmacokinetics (PK) and pharmacodynamics (PD).

Methods: Healthy Chinese adults aged 18–65 years with unknown genotypes from a bioequivalence trial were included according to the protocol registered at ClinicalTrial.org (NCT03161496). All subjects received a single dose (150 mg) of dabigatran etexilate. PK (main outcomes: area under the concentration-time, AUC0-t, of total and free dabigatran) and PD (main outcomes: anti-FIIa activity, APTT, and PT) parameters were evaluated. Whole-exome sequencing and genome-wide association analyses were performed. Additionally, candidate gene association analyses related to dabigatran were conducted.

Results: A total of 118 healthy Chinese subjects were enrolled in this study. According to the p-value suggestive threshold (1.0 × 10−4), the following three SNPs were found to be associated with the AUC0–t of total dabigatran: SLC4A4 SNP rs138389345 (p = 5.99 × 10−5), FRAS1 SNP rs6835769 (p = 6.88 × 10−5), and SULT1A1 SNP rs9282862 (p = 7.44 × 10−5). Furthermore, these SNPs were also found to have significant influences on the AUC0–t of free dabigatran, maximum plasma concentration, and anti-FIIa activity (p &lt; 0.05). Moreover, we identified 30 new potential SNPs of 13 reported candidate genes (ABCB1, ABCC2, ABCG2, CYP2B6, CYP1A2, CYP2C19, CYP3A5, CES1, SLCO1B1, SLC22A1, UGT1A1, UGT1A9, and UGT2B7) that were associated with drug metabolism.

Conclusion: Genetic variations were indeed found to impact dabigatran metabolism in a population of healthy Chinese subjects. Further research is needed to explore the more detailed functions of these SNPs. Additionally, our results should be verified in studies that use larger sample sizes and investigate other ethnicities.

Bleeding Risk Following Systemic Fluconazole or Topical Azoles in Patients with Atrial Fibrillation on Apixaban, Rivaroxaban, or Dabigatran

BACKGROUND

Bleeding safety in relation to use of systemic fluconazole and topical azoles among patients with atrial fibrillation treated with apixaban, rivaroxaban, or dabigatran is insufficiently explored, despite clinical relevance and several reports suggesting associations.

METHODS

Using nationwide Danish registers, we identified patients with atrial fibrillation initiated on apixaban, rivaroxaban, or dabigatran from 2012-2018. We investigated associations between bleeding incidents and systemic fluconazole or topical azole treatment using a case-crossover design with 30-day exposure windows and reported odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

We included 32,340 (36%), 32,409 (36%), and 24,940 (28%) patients initiated on apixaban, rivaroxaban, and dabigatran, respectively. Patients on apixaban were older (median age: 77 years; interquartile range [IQR] 70-84) compared with rivaroxaban users (median age: 75 years; IQR 68-82) and patients on dabigatran (median age: 73 years; IQR 66-80). Apixaban users had a significantly increased risk of bleeding following exposure to systemic fluconazole: odds ratio (OR) 3.5; 95% confidence interval (CI), 1.4-10.6. No increased risk was found among rivaroxaban and dabigatran users: ORs of 0.9 (95% CI, 0.2-3.0) and 1.7 (95% CI, 0.5-5.6), respectively. As to bleeding risk pertaining to topical azole exposure among apixaban, rivaroxaban, and dabigatran users, no association was found, with corresponding ORs of 0.8 (95% CI, 0.5-1.3); 1.3 (95% CI, 0.9-2.1); and 1.2 (95% CI 0.8-1.8), respectively.

CONCLUSION

In patients with atrial fibrillation on either apixaban, rivaroxaban, or dabigatran, an association between an elevated bleeding risk and use of systemic fluconazole was found among patients on apixaban. We found no increased risk of bleeding following co-exposure to topical azoles.

The value and limitations of new oral anticoagulant plasma level assessments

The class of new oral anticoagulants (NOACs) has been developed to provide reliable oral anticoagulation without the need for therapeutic drug monitoring. Based on phase I and II trials and pharmacokinetic and pharmacodynamic modeling, fixed drug doses have been selected for large phase III clinical trials for each currently available NOAC. In these trials, the use of the fixed dose without plasma level assessments was shown to be at least as effective and at least as safe as vitamin K antagonists with continuous therapeutic drug monitoring. Real world evidence reaffirms that the use of a fixed NOAC dose without plasma level assessment is safe and effective in a large variety of patients. Nevertheless, measurement of NOAC plasma levels can add information that may be useful in some clinical scenarios. This review discusses the possible use cases, the limitations, and the practical implementation of measuring NOAC plasma concentrations.

Inter- and intra-individual concentrations of direct oral anticoagulants: The KIDOAC study

BACKGROUND

Direct oral anticoagulants (DOACs) do not require concentration monitoring. However, whether DOAC concentrations are stable and their variation between and within patients is not well studied.

METHODS

Patients on vitamin K antagonists (VKA) who switched to rivaroxaban, apixaban, or dabigatran were included between 2018 and 2020. Blood was drawn at DOAC trough and peak concentrations at week 0, 2, and 8. Plasma drug concentrations were determined by anti-factor Xa concentrations (rivaroxaban, apixaban) or diluted thrombin time (dabigatran). Inter- and intra-individual variability was assessed by calculating the coefficient of variation (CV). Linear regression models were employed to evaluate associations between DOAC trough concentrations and previous VKA dosage, creatinine clearance, and body mass index (BMI).

RESULTS

One hundred fifty-two patients were included, of whom 96 (63%) were male and with a mean age of 73.9 ± 8.4 years. For the inter-individual variability, the CV ranged between 48% and 81% for trough values and between 25% and 69% for peak values among patients using the recommended DOAC dose. Intra-individual variability was substantially lower, as here the CV ranged between 18% and 33% for trough values and between 15% and 29% for peak values among patients using the recommended DOAC dose. Previous VKA dosage and creatinine clearance were inversely associated with DOAC trough concentrations. No association was found between BMI and DOAC trough concentrations.

CONCLUSION

Inter-individual variability of DOAC concentrations was higher than intra-individual variability. Lower previous VKA dosage and creatinine clearance were associated with higher DOAC trough concentrations. These findings support further study into an optimal target range, in which the risks of both bleeding and thrombosis are minimal.

Satisfaction With Oral Anticoagulants Among Patients With Atrial Fibrillation: A Prospective Observational Study

Background

Satisfaction with treatment has been identified as an important contributing factor to adherence with oral anticoagulant (OAC) therapy in patients with atrial fibrillation (AF). We aimed to evaluate the satisfaction level of patients with AF regarding OAC use over time, using validated patient-reported outcome instruments, and to identify associated patient characteristics.

Methods

Participants were recruited from specialized AF clinics in Canada. Eligible AF patients who were prescribed OACs were followed for up to 2 years. Participants were interviewed via telephone every 3-4 months using a structured survey. The Treatment Satisfaction Questionnaire for Medication (TSQM II) and the Anti-Clot Treatment Scale (ACTS) were used to measure satisfaction over time.

Results

Among the 306 participants, satisfaction scores on the TSQM II and ACTS instruments were high. Unadjusted analyses showed significantly greater satisfaction with the burden of therapy with direct OACs (DOACs) compared to that with warfarin (small-magnitude effect) and greater satisfaction with the convenience of rivaroxaban, compared with that of all other OACs (moderate-magnitude effect). After adjustment for all other variables, vitamin K antagonist therapy was associated with greater global satisfaction than was DOAC treatment. Satisfaction with benefit and burden as measured by the ACTS scale, and global satisfaction on the TSQM II scale, tended to increase over time. Patient factors that were somewhat consistently associated with greater satisfaction were female sex and younger age.

Conclusions

Patients with AF were highly satisfied with their therapy, with few differences among OAC classes and individual OACs. Individual patients may or may not be more satisfied with DOAC than VKA therapy, and regardless of the OAC prescribed, the may require significant support to maintain therapy adherence.

How lower doses of direct oral anticoagulants are interpreted in clinical practice: a national survey of the Italian Atherosclerosis, Thrombosis and Vascular Biology (ATVB) Study Group

AIM

To evaluate the current interpretation of the lower doses of direct oral anticoagulants (DOAC) dabigatran, apixaban, edoxaban and rivaroxaban in nonvalvular atrial fibrillation.

METHODS

A questionnaire of 14 statements to which the possible answers were fully agree/partially agree/partially disagree/fully disagree or yes/no was prepared within the board of the Italian Atherosclerosis, Thrombosis and Vascular Biology Study Group and forwarded to individual Italian physicians.

RESULTS

A total of 620 complete questionnaires were received from nearly all the Italian regions and physicians of various medical specialists, either enabled or not for the prescription of DOAC. A wide agreement was found as regards the pharmacological, as well as clinical consequences of the administration of the lower dose of factor-Xa inhibitors both in patients with and without clinical and/or laboratory criteria requiring dose reduction. Wide agreement was also found as regards the presence of moderate kidney insufficiency in selecting the dose of DOAC. Instead, more debated were issues regarding the proportionality between dabigatran dose and plasma concentration and selection of dabigatran dose, as well as the role of measuring drug plasma concentration and/or determine the anticoagulant activity of factor-Xa inhibitors when used at the lower dose.

CONCLUSION

The interpretation of the lower doses of DOAC in current Italian clinical practice appears largely correct and shared. Because of the persistence of some residual uncertainties, essentially regarding dabigatran, however, continuous educational effort still appears warranted.

Antithrombotic and Antiplatelet Drug Toxicity

Anticoagulant and antiplatelet drugs target a specific portion of the coagulation cascade or the platelet activation and aggregation pathway. The primary toxicity associated with these agents is hemorrhage. Understanding the pharmacology of these drugs allows the treating clinician to choose the correct antidotal therapy. Reversal agents exist for some of these drugs; however, not all have proven patient-centered outcomes. The anticoagulants covered in this review are vitamin K antagonists, heparins, fondaparinux, hirudin derivatives, argatroban, oral factor Xa antagonists, and dabigatran. The antiplatelet agents reviewed are aspirin, adenosine diphosphate antagonists, dipyridamole, and glycoprotein IIb/IIIa antagonists. Additional notable toxicities are also reviewed.

Direct Oral Anticoagulants: From Randomized Clinical Trials to Real-World Clinical Practice

Direct oral anticoagulants (DOACs) are a more manageable alternative than vitamin K antagonists (VKAs) to prevent stroke in patients with nonvalvular atrial fibrillation and to prevent and treat venous thromboembolism. Despite their widespread use in clinical practice, there are still some unresolved issues on optimizing their use in particular clinical settings. Herein, we reviewed the current clinical evidence on uses of DOACs from pharmacology and clinical indications to safety and practical issues such as drugs and food interactions. Dabigatran is the DOAC most affected by interactions with drugs and food, although all DOACs demonstrate a favorable pharmacokinetic profile. Management issues associated with perioperative procedures, bleeding treatment, and special populations (pregnancy, renal and hepatic impairment, elderly, and oncologic patients) have been discussed. Literature evidence shows that DOACs are at least as effective as VKAs, with a favorable safety profile; data are particularly encouraging in using low doses of edoxaban in elderly patients, and edoxaban and rivaroxaban in the treatment of venous thromboembolism in oncologic patients. In the next year, DOAC clinical indications are likely to be further extended.

Oral Anticoagulant Treatment in Patients with Atrial Fibrillation and Chronic Kidney Disease

Over the past few decades, a series of innovative medicines have been developed in order to optimize anticoagulation therapy for atrial fibrillation (AF). As a result, a number of nonvitamin K antagonist oral anticoagulants (NOAC) that directly target the enzymatic activity of factor II and factor Xa have been successfully licensed providing a more predictable effect and better safety profile compared to conventional anticoagulants (heparins and vitamin K antagonists (VKAs)). However, comparative efficacy and safety data is limited in patients with advanced chronic kidney disease (i.e., CKD stage 4/5 and end stage renal disease) because patients with estimated glomerular filtration rate (eGFR) < 30 mL/min/1.73 m² were actively excluded from landmark trials, thus representing a major clinical limitation for the currently available agents. However, the renal function of AF patients can be altered over time. On the other hand, patients with CKD have an increased risk of developing AF. This review article will provide an overview of current concepts and recent evidence guiding the clinical use of NOACs in patients with CKD requiring chronic anticoagulation, and the associated risks and benefits of treatment in this specific patient population.

Using Pharmacogenetics of Direct Oral Anticoagulants to Predict Changes in Their Pharmacokinetics and the Risk of Adverse Drug Reactions

Dabigatran, rivaroxaban, apixaban, and edoxaban are direct oral anticoagulants (DOACs) that are increasingly used worldwide. Taking into account their widespread use for the prevention of thromboembolism in cardiology, neurology, orthopedics, and coronavirus disease 2019 (COVID 19) as well as their different pharmacokinetics and pharmacogenetics dependence, it is critical to explore new opportunities for DOACs administration and predict their dosage when used as monotherapy or in combination with other drugs. In this review, we describe the details of the relative pharmacogenetics on the pharmacokinetics of DOACs as well as new data concerning the clinical characteristics that predetermine the needed dosage and the risk of adverse drug reactions (ADRs). The usefulness of genetic information before and shortly after the initiation of DOACs is also discussed. The reasons for particular attention to these issues are not only new genetic knowledge and genotyping possibilities, but also the risk of serious ADRs (primarily, gastrointestinal bleeding). Taking into account the effect of the carriership of single nucleotide variants (SNVs) of genes encoding biotransformation enzymes and DOACs metabolism, the use of these measures is important to predict changes in pharmacokinetics and the risk of ADRs in patients with a high risk of thromboembolism who receive anticoagulant therapy.

Variants in CDHR3, CACNAC1, and LTA Genes Predisposing Sensitivity and Response to Warfarin in Patients with Cardiovascular Disease

Introduction

Warfarin has been in use for more than 60 years; however, it has serious side effects including major bleeding. The high interpatient variability in the required dose impacts the sensitivity and responsiveness to warfarin in different patients. This study aims to assess the influence of CDHR3, CACNAC1, and LTA gene polymorphisms on the variability of warfarin dose requirements and susceptibility to coronary heart disease in the Jordanian population.

Methods

This study was conducted in the anti-coagulation clinic in Queen Alia Heart Institute in Amman, with 212 patients in total. Three SNPs were genotyped within CDHR3 (rs10270308), CACNAC1 (rs216013), and LTA (rs1041981) genes.

Results

Our findings revealed that patients with LTA polymorphism are more prone to warfarin sensitivity than others. Furthermore, carriers of the LTA polymorphism needed a lower initial dose of warfarin and are associated with less variation in doses required to achieve target INR.

Conclusion

The current study could help in understanding the role of genetic variability in warfarin dosing and matching patients to different treatment options. Clinical applications of these findings for warfarin treatment may also contribute to improving the efficacy and safety of warfarin treatment in Jordanian patients with cardiovascular disease.

Pharmacokinetics and Pharmacogenetics of Dabigatran

Dabigatran etexilate is a prodrug of dabigatran, a oral direct inhibitor of thrombin. Pharmacokinetics of dabigatran etexilate doesn’t have the disadvantages of vitamin K antagonists. However, pharmacokinetics and pharmacogenetics of dabigatran are variable. This can affect both effectiveness and safety of anticoagulant therapy. It is considered that CES1 enzyme and P-glycoprotein (CES1 and ABCB1 genes accordingly) play important role in pharmacokinetics of dabigatran etexilate. UDP-glucuronosyltransferase enzymes UGT2B15, UGT1A9, UGT2B7 (UGT2B15, UGT1A9, UGT2B7 genes accordingly) take part in the metabolism of active dabigatran. Presence of these gene’s single-nucleotide variants (SNV) can affect effectiveness and safety of dabigatran etexilate usage. The goal of this review is analysis of associated researches of SNV genes CES1 and ABCB1 and search for new candidate genes that reveal effectiveness and safety of dabigatran etexilate usage.

Materials and methods. The search for full-text publications in Russian and English languages containing key words “dabigatran etexilate”, “dabigatran”, “pharmacokinetics”, “effectiveness”, “safety” was carried out amongst literature of the past twenty years with the use of eLibrary, PubMed, Web of Science, OMIM data bases. Pharmacokinetics and pharmacogenetics of dabigatran etexilate are considered in this review. The hypothesis about UDP-glucuronosyltransferase enzymes influence on dabigatran metabolism was examined. Nowadays more than 2000 SNV CES1 and ABCB1 genes are identified, but their potential influence on pharmacokinetics of dabigatran etexilate and its active metabolite (dabigatran) in clinical practice needs to be further researched. Role of SNV UDP-glucuronosyltransferase genes (UGT2B15, UGT1A9, UGT2B7) in dabigatran’s effectiveness and safety is not explored enough. However, UGT2B15 gene can be a potential candidate gene for research on safety of this drug.

Influence of PSRC1, CELSR2, and SORT1 Gene Polymorphisms on the Variability of Warfarin Dosage and Susceptibility to Cardiovascular Disease

Background

Cardiovascular disease is one of the most common causes of morbidity and mortality worldwide. Several cardiovascular diseases require therapy with warfarin, an anticoagulant with large interindividual variability resulting in dosing difficulties. The selected genes and their polymorphisms have been implicated in several Genome-Wide Association Study (GWAS) to be associated with cardiovascular disease.

Objective

The goal of this study is to discover if there are any associations between rs646776 of PSRC1, rs660240 and rs12740374 of CELSR2, and rs602633 of SORT1 to coronary heart disease (CHD) and warfarin dose variability in patients diagnosed with cardiovascular disease undergoing warfarin therapy.

Methods

The study was directed at the Queen Alia Hospital Anticoagulation Clinic in Amman, Jordan. DNA was extracted and genotyped using the Mass ARRAY™ system, statistical analysis was done using SPSS.

Results

The study found several associations between the selected SNPs with warfarin, but none with cardiovascular disease. All 4 studied SNPs were found to be correlated to warfarin sensitivity during the stabilization phase except rs602633 and with warfarin dose variability at the initiation phase. CELSR2 SNPs also showed association with dose variability during the stabilization phase. Also, rs646776 and rs12740374 were linked to warfarin sensitivity over the initiation phase. Only rs602633 was associated with INR treatment outcomes.

Conclusion

The findings presented in this study found new pharmacogenomic associations for warfarin, that warrant further research in the field of genotype-guided warfarin dosing.

Non-vitamin K antagonist oral anticoagulants for stroke prevention in atrial fibrillation: safety issues in the elderly

INTRODUCTION

Non-vitamin K antagonist oral anticoagulants (NOACs) are increasingly used for stroke prevention in patients with atrial fibrillation (AF). Since NOACs are predominantly used in the elderly with AF at high risk for stroke and bleeding and with comorbidities requiring polypharmacy, it is important to assess their safety and efficacy in this population.

AREAS COVERED

We review changes in pharmacokinetics and pharmacodynamics observed with senescence and the effect on NOACs and drug and food interactions. We also provide an update on challenges related to NOAC use in situations that increases the risk for bleeding or require temporary discontinuation and address practical issues in the elderly AF patients managed on NOACs. Clinical studies and trials with cardiovascular outcomes reported from January 1990 to August 2020 were identified through the Medline database using PubMed, Cochrane Library, and EMBASE database.

EXPERT OPINION

NOACs are highly effective in preventing stroke in AF patients with non-inferior or superior efficacy to warfarin, with reduced risk of major bleeding. However, in the older-elderly, evidence comes mainly from observational studies or extrapolation from studies in populations with minimal functional limitations or comorbidities. The high upfront cost and out-of-pocket expense for copayment or deductibles also limit the use of this effective therapy in a substantial number of patients. The cost reduction may further improve long-term use for NOACs in stroke prevention in elderly patients with AF.

Binding of direct oral anticoagulants to the FA1 site of human serum albumin

The anticoagulant therapy is widely used to prevent and treat thromboembolic events. Until the last decade, vitamin K antagonists were the only available oral anticoagulants; recently, direct oral anticoagulants (DOACs) have been developed. Since 55% to 95% of DOACs are bound to plasma proteins, the in silico docking and ligand-binding properties of drugs apixaban, betrixaban, dabigatran, edoxaban, and rivaroxaban and of the prodrug dabigatran etexilate to human serum albumin (HSA), the most abundant plasma protein, have been investigated. DOACs bind to the fatty acid (FA) site 1 (FA1) of ligand-free HSA, whereas they bind to the FA8 and FA9 sites of heme-Fe(III)- and myristic acid-bound HSA. DOACs binding to the FA1 site of ligand-free HSA has been validated by competitive inhibition of heme-Fe(III) recognition. Values of the dissociation equilibrium constant for DOACs binding to the FA1 site (ie, ^calc K_DOAC ) derived from in silico docking simulations (ranging between 1.2 × 10^-8 M and 1.4 × 10^-6 M) agree with those determined experimentally from competitive inhibition of heme-Fe(III) binding (ie, ^exp K_DOAC ; ranging between 2.5 × 10^-7 M and 2.2 × 10^-6 M). In addition, this study highlights the inequivalence of rivaroxaban binding to mammalian serum albumin. Given the HSA concentration in vivo (~7.5 × 10^-4 M), values of K_DOAC here determined indicate that the formation of the HSA:DOACs complexes in the absence and presence of FAs and heme-Fe(III) may occur in vivo. Therefore, HSA appears to be an important determinant for DOACs transport.

Adverse Drug Reactions in Patients with CKD

BACKGROUND AND OBJECTIVES

Little is known about the burden of adverse drug reactions in CKD. We estimated the incidence of overall and serious adverse drug reactions and assessed the probability of causation, preventability, and factors associated with adverse drug reactions in patients seen by nephrologists.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The Chronic Kidney Disease-Renal Epidemiology and Information Network cohort included 3033 outpatients (65% men) with CKD and eGFR<60 ml/min per 1.73 m², with follow-up for 2 years. Adverse drug reactions were identified from hospitalization reports, medical records, and participant interviews and finally assessed for causality, preventability, and immediate therapeutic management by experts in pharmacology.

RESULTS

Median (interquartile range) age was 69 (60-76) years old; 55% had eGFR≥30 ml/min per 1.73 m², and 45% had eGFR<30 ml/min per 1.73 m². Participants were prescribed a median (range) of eight (five to ten) drugs. Over 2 years, 536 patients had 751 adverse drug reactions, 150 (in 125 participants) classified as serious, for rates of 14.4 (95% confidence interval, 12.6 to 16.5) and 2.7 (95% confidence interval, 1.7 to 4.3) per 100 person-years, respectively. Among the serious adverse drug reactions, 32% were considered preventable or potentially preventable; 16 caused death, directly or indirectly. Renin-angiotensin system inhibitors (15%), antithrombotic agents (14%), and diuretics (10%) were the drugs to which the most adverse drug reactions were imputed, but antithrombotic agents caused 34% of serious adverse drug reactions. The drug was discontinued in 71% of cases, at least temporarily. Adjusted hazard ratios for serious adverse drug reaction were significantly higher in patients with eGFR<30 versus ≥30 ml/min per 1.73 m² (1.8; 95% confidence interval, 1.3 to 2.6), in those prescribed more than ten versus less than five medications (2.4; 95% confidence interval, 1.1 to 5.2), or in those with poor versus good adherence (1.6; 95% confidence interval, 1.4 to 2.4).

CONCLUSIONS

Adverse drug reactions are common and sometimes serious in patients with CKD. Many serious adverse drug reactions may be preventable. Some specific pharmacologic classes, particularly antithrombotic agents, are at risk of serious adverse drug reactions.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Chronic Kidney Disease-Renal Epidemiology and Information Network (CKD-REIN), NCT03381950.

Risk of Bleeding with Exposure to Warfarin and Nonsteroidal Anti-Inflammatory Drugs: A Systematic Review and Meta-Analysis

BACKGROUND

 Warfarin use can trigger the occurrence of bleeding independently or as a result of a drug-drug interaction when used in combination with nonsteroidal anti-inflammatory drugs (NSAIDs).

OBJECTIVES

 This article examines the risk of bleeding in individuals exposed to concomitant warfarin and NSAID compared with those taking warfarin alone (Prospero Registry ID 145237).

METHODS

 PubMed, EMBASE, Scopus, and Web of Science were searched. The primary outcome of interest was gastrointestinal bleeding and general bleeding. Summary effects were calculated to estimate average treatment effect using random effects models. Heterogeneity was assessed using Cochran's Q and I ². Risk of bias was also assessed using the Agency for Healthcare Research and Quality bias assessment tool.

RESULTS

 A total of 651 studies were identified, of which 11 studies met inclusion criteria for meta-analysis. The odds ratio (OR) for gastrointestinal bleeding when exposed to warfarin and an NSAID was 1.98 (95% confidence interval [CI]: 1.55-2.53). The risk of gastrointestinal bleeding was also significantly elevated with exposure to a COX-2 inhibitor and warfarin relative to warfarin alone (OR = 1.90, 95% CI: 1.46-2.46). There was an increased risk of general bleeding with the combination of warfarin with NSAIDs (OR = 1.58, 95% CI: 1.18-2.12) or COX-2 inhibitors (OR = 1.54, 95% CI: 0.86-2.78) compared with warfarin alone.

CONCLUSION

 Risk of bleeding is significantly increased among persons taking warfarin and a NSAID or COX-2 inhibitor together as compared with taking warfarin alone. It is important to caution patients about taking these medications in combination.