Clinical Pharmacokinetics and Pharmacodynamics of Direct Oral Anticoagulants in Patients with Renal Failure

Use of direct oral anticoagulants in patients on chronic hemodialysis: Contemporary appraisal on the role for patients with atrial fibrillation

Atrial fibrillation (AF) is common in patients with chronic kidney disease (CKD) undergoing hemodialysis and in this patient population, management in terms of oral anticoagulation (OAC) presents unique challenges due to the increased risk of both thromboembolic events and bleeding complications. The attributable risk of AF for stroke may differ from patients without CKD, raising the question if OAC is indicated at all. Historically, vitamin K antagonists (VKA) have been the standard treatment for anticoagulation in AF; however, direct oral anticoagulants (DOACs) have emerged as an alternative therapeutic option, whereby data from prospective randomised trials with hemodialysis patients is limited resulting in great variability of practice and guideline recommendations. This review summarizes existing data sources regarding the use and benefit of oral anticoagulation with VKA and DOAC in hemodialysis patients.

Anticoagulation in Chronic Kidney Disease

The nuanced landscape of anticoagulation therapy in patients with chronic kidney disease (CKD) presents a formidable challenge, intricately balancing the dual hazards of hemorrhage and thrombosis. These patients find themselves in a precarious position, teetering on the edge of these risks due to compromised platelet functionality and systemic disturbances within their coagulation frameworks. The management of such patients necessitates a meticulous approach to dosing adjustments and vigilant monitoring to navigate the perilous waters of anticoagulant therapy. This is especially critical considering the altered pharmacokinetics in CKD, where the clearance of drugs is significantly impeded, heightening the risk of accumulation and adverse effects. In the evolving narrative of anticoagulation therapy, the introduction of direct oral anticoagulants (DOACs) has heralded a new era, offering a glimmer of hope for those navigating the complexities of CKD. These agents, with their promise of easier management and a reduced need for monitoring, have begun to reshape the contours of care, particularly for patients not yet on dialysis. However, this is not without its caveats. The application of DOACs in the context of advanced CKD remains a largely uncharted territory, necessitating a cautious exploration to unearth their true potential and limitations. Moreover, the advent of innovative strategies such as left atrial appendage occlusion (LAAO) underscores the dynamic nature of anticoagulation therapy, potentially offering a tailored solution for those at the intersection of CKD and elevated stroke risk. Yet the journey toward integrating such advancements into standard practice is laden with unanswered questions, demanding rigorous investigation to illuminate their efficacy and safety across the spectrum of kidney disease. In summary, the management of anticoagulation in CKD is a delicate dance, requiring a harmonious blend of precision, caution, and innovation. As we venture further into this complex domain, we must build upon our current understanding, embracing both emerging therapies and the need for ongoing research. Only then can we hope to offer our patients a path that navigates the narrow strait between bleeding and clotting, toward safer and more effective care.

A real-world exploration into clinical outcomes of direct oral anticoagulant therapy in people with chronic kidney disease: a large hospital-based study

BACKGROUND

There is limited evidence to support definite clinical outcomes of direct oral anticoagulant (DOAC) therapy in chronic kidney disease (CKD). By identifying the important variables associated with clinical outcomes following DOAC administration in patients in different stages of CKD, this study aims to assess this evidence gap.

METHODS

An anonymised dataset comprising 97,413 patients receiving DOAC therapy in a tertiary health setting was systematically extracted from the multidimensional electronic health records and prepared for analysis. Machine learning classifiers were applied to the prepared dataset to select the important features which informed covariate selection in multivariate logistic regression analysis.

RESULTS

For both CKD and non-CKD DOAC users, features such as length of stay, treatment days, and age were ranked highest for relevance to adverse outcomes like death and stroke. Patients with Stage 3a CKD had significantly higher odds of ischaemic stroke (OR 2.45, 95% Cl: 2.10-2.86; p = 0.001) and lower odds of all-cause mortality (OR 0.87, 95% Cl: 0.79-0.95; p = 0.001) on apixaban therapy. In patients with CKD (Stage 5) receiving apixaban, the odds of death were significantly lowered (OR 0.28, 95% Cl: 0.14-0.58; p = 0.001), while the effect on ischaemic stroke was insignificant.

CONCLUSIONS

A positive effect of DOAC therapy was observed in advanced CKD. Key factors influencing clinical outcomes following DOAC administration in patients in different stages of CKD were identified. These are crucial for designing more advanced studies to explore safer and more effective DOAC therapy for the population.

Anticoagulation management in elderly patients with proximal femur fractures - overview of current concepts

Objectives

Proximal femur fractures (PFF) are common injuries in elderly patients and can have considerable effects on their quality of life, morbidity, and mortality. Due to pre-existing comorbidities, the prevalence of anticoagulated patients is increasing. The right timing for surgery and perioperative anticoagulation treatment remains controversial.

Content

This overview aims to summarize current practices in the pre- and postoperative anticoagulation management and the recommended time to surgery in elderly patients with PFF.

Summary and Outlook

Time to surgery for anticoagulated patients is often prolonged due to worries about serious perioperative bleeding and higher transfusion demands. But the delay of surgical PFF treatment increases the risk for perioperative complications like pulmonary embolism, pneumonia, deep vein thrombosis and urinary tract infections. Early surgery can be achieved with a consistent and interdisciplinary perioperative anticoagulation management. Antiplatelets do not have to be discontinued and surgery should be performed early without delay. For patients taking vitamin K antagonists (VKA) an INR less than 1.5 is recommended prior to surgery, which can be achieved by pausing VKA intake or by administering vitamin K, prothrombin complex concentrate (PCC) or fresh frozen plasma (FFP). For the treatment with direct oral anticoagulants (DOAC) a plasma drug level of under 50 pg/mL is considered safe for surgery. If the plasma level can not be determined, a gap of 24 h between the last DOAC dose and surgery is recommended. The systemic administration of tranexamic acid can reduce overall blood loss and transfusion rates in anticoagulated patients with PFF. Surgical treatment of PFF should be performed within 24 h, as delayed surgery increases the risk for perioperative complications. This also applies to anticoagulated patients, when clinically appropriate. International and interdisciplinary guidelines are necessary to ensure early and appropriate treatment of anticoagulated elderly patients with PFF.

Hemorrhagic Coagulation Disorders and Ischemic Stroke: How to Reconcile Both?

Coagulation and fibrinolytic system disorders are conditions in which the blood's ability to clot is impaired, resulting in an increased risk of thrombosis or bleeding. Although these disorders are the expression of two opposing tendencies, they can often be associated with or be a consequence of each other, contributing to making the prognosis of acute cerebrovascular events more difficult. It is important to recognize those conditions that are characterized by dual alterations in the coagulation and fibrinolytic systems to reduce the prognostic impact of clinical conditions with difficult treatment and often unfortunate outcomes. Management of these individuals can be challenging, as clinicians must balance the need to prevent bleeding episodes with the potential risk of clot formation. Treatment decisions should be made on an individual basis, considering the specific bleeding disorder, its severity, and the patient's general medical condition. This review aims to deal with all those forms in which coagulation and fibrinolysis represent two sides of the same media in the correct management of patients with acute neurological syndrome. Precision medicine, personalized treatment, advanced anticoagulant strategies, and innovations in bleeding control represent future directions in the management of these complex pathologies in which stroke can be the evolution of two different acute events or be the first manifestation of an occult or unknown underlying pathology.

Anti-coagulant Treatment of Cancer-Associated Thrombosis in Frail Patients: Impact of Frailties on the Management of Drug-Drug Interactions

Low molecular weight heparins (LMWH) and anti-Xa direct oral anti-coagulants (DOACs) are recommended for the long-term treatment of cancer-associated thrombosis (CAT) based on well-documented randomised controlled trials. Anti-Xa DOACs are viewed as a first choice for the treatment of patients with CAT. A large number of drug-drug interactions have been reported between DOACs and chemotherapy drugs, modifying circulating levels of DOAC leading to fears of increased bleeding risks or thrombotic recurrence. Progresses in anti-neoplastic therapies have improved the prognosis and the survival, thus increasing the prevalence of frail patients with cancer. However, since frailties tend to be excluded from large trials due to multiple co-morbidities, current guidelines are not fully applicable to this population. The management of these frail patients with CAT is particularly complex and requires a risk assessment on a case-by-case basis with specific focus on cancer, patient-related risk factors and drug-drug interactions. In this brief review we have identified age, co-morbidities and co-medications as key factors of frailty that require careful attention and we have developed a therapeutic decision algorithm to help clinicians optimising the use of anti-coagulants in patients with cancer with CAT, especially in case of anti-Xa DOACs concomitant medications. With the evaluation of the bleeding risk according to the type of cancer, and anticipating drug-drug interactions intensity, taking into account patient frailties allows the optimisation of the anti-coagulant choice. A systematic collaboration between oncologists, vascular pathology specialists and pharmacists is warranted to ensure an optimal patient management. Clinical studies are needed to determine the real impact of these interactions.

[Proper use of oral anticoagulants in the elderly patient]

Direct oral anticoagulants (DOACs) are tending to supplant antivitamin K inhibitors (VKAs) in their common indications, dominated in elderly patients by atrial fibrillation and venous thromboembolism. Nevertheless, it remains necessary to know how best to use VKAs for which there are still indications. It is also important not to assume that AODs can be prescribed without risk, while ignoring certain particularities in their handling, particularly in the most fragile patients with co-morbidities and multiple medications.

Therapeutic Drug Monitoring of Direct Oral Anticoagulants in Patients with Extremely Low and High Body Weight-Pilot Study

Phase III clinical trials for individual direct oral anticoagulants (DOACs) contained a limited representation of subjects with abnormal body weight, which were mostly limited to a BMI > 40 kg/m2, or body weight > 120 kg for obese subjects, and <50 kg for underweight subjects. Although low or high body weight is not a contraindication to DOACs therapy, it can significantly affect the safety and effectiveness of treatment. Due to the limited amount of clinical data on the use of DOACs in extremely abnormal weight ranges, optimal pharmacotherapy in this group of patients is a matter of controversy. The objective of this study was to evaluate the pharmacokinetics of DOAC properties in patients with abnormal body weight beyond the established cut-off points in the phase III studies for rivaroxaban, apixaban, and dabigatran. In total, 38 patients took DOACs for at least 12 months for non-valvular atrial fibrillation in 2019-2021. Blood samples were collected before the planned intake of the drug and 4 h after its administration. The determined concentrations of DOACs were statistically analyzed in relation to body weight, age, and eGFR (estimated Glomerular Filtration Rate). Among subjects taking apixaban, rivaroxaban, and dabigatran, the smallest representation of patients who achieved therapeutic concentrations were those treated with dabigatran. The population of people with abnormal body weight is a potential risk group of patients, in which some of them do not reach the therapeutic range of DOACs.

Management of Gastrointestinal Bleeding and Resumption of Oral Anticoagulant Therapy in Patients with Atrial Fibrillation: A Multidisciplinary Discussion

Direct oral anticoagulants (DOACs) are recommended for the prevention of thromboembolism in patients with atrial fibrillation (AF), and are now preferred over vitamin K antagonists due to their beneficial efficacy and safety profile. However, all oral anticoagulants carry a risk of gastrointestinal (GI) bleeding. Although the risk is well documented and acute bleeding well codified, there is limited high-quality evidence and no guidelines to guide physicians on the optimal management of anticoagulation after a GI bleeding event. The aim of this review is to provide a multidisciplinary critical discussion of the optimal management of GI bleeding in patients with AF receiving oral anticoagulants to help physicians provide individualized treatment for each patient and optimize outcomes. It is important to perform endoscopy when a patient presents with bleeding manifestations or hemodynamic instability to determine the bleed location and severity of bleeding and then perform initial resuscitation. Administration of all anticoagulants and antiplatelets should be stopped and bleeding allowed to resolve with time; however, anticoagulant reversal should be considered for patients who have life-threatening bleeding or when the bleeding is not controlled by the initial resuscitation. Anticoagulation needs to be timely resumed considering that bleeding risk outweighs thrombotic risk when anticoagulation is resumed early after the bleeding event. To prevent further bleeding, physicians should prescribe anticoagulant therapy with the lowest risk of GI bleeding, avoid medications with GI toxicity, and consider the effect of concomitant medications on potentiating the bleeding risk.

Oral Anticoagulation in Patients With Advanced Chronic Kidney Disease and Atrial Fibrillation: Beyond Anticoagulation

The optimal approach to prevent stroke and systemic embolism in patients with advanced chronic kidney disease (CKD) and atrial fibrillation remains unresolved. We conducted a narrative review to explore areas of uncertainty and opportunities for future research. First, the relationship between atrial fibrillation and stroke is more complex in patients with advanced CKD than in the general population. The currently employed risk stratification tools do not adequately discriminate between patients deriving a net benefit and those suffering a net harm from oral anticoagulation. Anticoagulation initiation should probably be more restrictive than is currently advocated by official guidelines. Recent evidence reveals that the superior benefit-risk profile of non-vitamin K antagonist oral anticoagulants (NOACs) vs vitamin K antagonists (VKAs) observed in the general population and in moderate CKD can be extended to advanced CKD. The NOACs yield better protection against stroke, cause less major bleeding, are associated with less acute kidney injury and a slower decline of CKD, and are associated with a lower incidence of cardiovascular events than VKAs. The VKAs may be harmful in CKD patients, in particular in patients with a high bleeding risk and labile international normalized ratio. The better safety and efficacy of NOACs as opposed to VKAs may be particularly evident in advanced CKD as a result of better on-target anticoagulation with NOACs, harmful off-target vascular effects of VKAs, and beneficial off-target vascular effects of NOACs. The intrinsic vasculoprotective effects of NOACs are supported by animal experimental evidence as well as by findings of large clinical trials and may result in use of NOACs beyond their anticoagulant properties.

Study of Modifications Induced by Continued Direct Oral Anticoagulant Therapy during Atrial Fibrillation Ablation Procedures on Standard Hemostasis Parameters

Background: Unfractionated heparin (UFH) is used as an anticoagulant during the atrial fibrillation (AF) ablation procedure to prevent the occurrence of thromboembolic events. Guidelines recommend an activated clotting time (ACT) greater than 300 s (s) based on studies of patients treated with vitamin K antagonist (VKA) for their AF. However, direct oral anticoagulants (DOACs) have supplanted VKAs in AF and are now used as first-line therapy. It is recommended not to interrupt them during the procedure, which could interfere with the ACT measures. Objective: To assess the real-life relationship between ACT, DOAC concentrations, and UFH anti-Xa activity in patients treated by uninterrupted DOAC therapy. Methods: We conducted a single-center retrospective study. We analyzed consecutive patients with AF who underwent catheter ablation under DOAC therapy. Results: In total, 40 patients were included, including 15 (37.5%), 20 (50.0%), and 5 (12.5%) on rivaroxaban, apixaban, and dabigatran, respectively. Baseline ACT was significantly lower in the apixaban group. ACT was linearly correlated with the residual concentration of apixaban and dabigatran but not with rivaroxaban. After UFH injection, ACT was linearly correlated with the anti-Xa activity, regardless of DOAC. Patients in the apixaban group received a higher total dose of UFH during the procedure to achieve a target ACT > 300 s, which resulted in significantly higher anti-Xa activity during the procedure. Conclusion: Our results raise the question of optimal management of intra-procedural heparin therapy and highlight the limitations of the ACT test, particularly in patients on apixaban.

Oral Anticoagulation Therapy in Atrial Fibrillation Patients with Advanced Chronic Kidney Disease: CODE-AF Registry

PURPOSE

Advanced chronic kidney disease (CKD), including end-stage renal disease (ESRD) on dialysis, increases thromboembolic risk among patients with atrial fibrillation (AF). This study examined the comparative safety and efficacy of direct-acting oral anticoagulant (DOAC) compared to warfarin or no oral anticoagulant (OAC) in AF patients with advanced CKD or ESRD on dialysis.

MATERIALS AND METHODS

Using data from the COmparison study of Drugs for symptom control and complication prEvention of AF (CODE-AF) registry, 260 non-valvular AF patients with advanced CKD (defined as estimated glomerular filtration rate <30 mL/min per 1.73/m²) or ESRD on dialysis were enrolled from June 2016 to July 2020. The study population was categorized into DOAC, warfarin, and no OAC groups; and differences in major or clinically relevant non-major (CRNM) bleeding, stroke/systemic embolism (SE), myocardial infarction/critical limb ischemia (CLI), and death were assessed.

RESULTS

During a median 24 months of follow-up, major or CRNM bleeding risk was significantly reduced in the DOAC group compared to the warfarin group [hazard ratio (HR) 0.11, 95% confidence interval (CI) 0.01 to 0.93, p=0.043]. In addition, the risk of composite adverse clinical outcomes (major or CRNM bleeding, stroke/SE, myocardial infarction/CLI, and death) was significantly reduced in the DOAC group compared to the no OAC group (HR 0.16, 95% CI 0.03 to 0.91, p=0.039).

CONCLUSION

Among AF patients with advanced CKD or ESRD on dialysis, DOAC was associated with a lower risk of major or CRNM bleeding compared to warfarin and a lower risk of composite adverse clinical outcomes compared to no OAC. ClinicalTrials.gov (NCT02786095).

Current Antithrombotic Therapy Strategies in Children with a Focus on Off-Label Direct Oral Anticoagulants-A Narrative Review

(1) Background: The incidence of thromboembolic events is relatively low in the general population, but it increases in hospitalized children and those who underwent thrombogenic procedures. Although the evidence regarding direct oral anticoagulants (DOACs) in children with venous thromboembolism (VTE) is growing, DOACs were excluded from existing guidelines due to the lack of reliable data at that moment. Therefore, current evidence on VTE management in children needs to be critically reviewed. (2) Methods: We have conducted a literature search in the Scopus, EMBASE, and MEDLINE databases using prespecified keywords to retrieve studies published between 2010 and 2022. (3) Results: Clinical trials highlighted that rivaroxaban and dabigatran had predictable pharmacokinetic and pharmacodynamic profiles in children, similar to those observed in adults. Dabigatran and rivaroxaban had a similar safety profile to standard therapy but improved thrombotic burden and resolution during follow-up. Most studies involving apixaban and edoxaban are ongoing, and results are awaited. (4) Conclusions: Dabigatran and rivaroxaban could be valid therapeutic options for VTE management in children. In the case of apixaban and edoxaban, results from ongoing clinical studies are required before using them in pediatric VTE.

Biopharmaceutics considerations for direct oral anticoagulants

Vitamin K antagonists (VKA) and direct oral anticoagulants (DOACs) have been clinically used in the treatment of coagulation disorders. There are four DOACs approved since 2010 (dabigatran etexilate, rivaroxaban, apixaban, and edoxaban), and they were designed to overcome the practical limitations of VKA. This review summarized biopharmaceutics considerations about DOACs, which are critically discussed, applying risk analyses to subside the further classification of these drugs according to the Biopharmaceutics Classification System (BCS). These discussions included data compiled about physicochemical properties, equilibrium solubility, permeability, and drug dissolution of DOACs. From the biopharmaceutics characteristics is possible to identify critical variables related to the absorption process, which can help in the design of new formulations. The data were compared with the criteria recommended by regulatory agencies for the biopharmaceutics classification according to the BCS. From that, these data may be used to discuss the approval of generic medicines by the BCS-based biowaiver, and the clinical risks arising from novel formulations with DOACs. However, although there are indications of biopharmaceutics classifications for DOACs, conclusive information to classify these compounds according to the BCS is lacking, requiring more experimental studies to achieve this aim. Conclusive information is essential for a safe decision about the biowaiver, as well as to guide the development of new formulations containing the DOACs.

Towards personalized antithrombotic management with drugs and devices across the cardiovascular spectrum

Intravascular thrombus formation and embolization are among the most frequent events leading to a number of cardiovascular conditions with high morbidity and mortality. The underlying causes are stasis of the circulating blood, genetic and acquired coagulation disorders, and reduced antithrombotic or prothrombotic properties of the vascular wall (Virchow's triad). In the venous system, intravascular thrombi can cause venous thrombosis and pulmonary and even peripheral embolism including ischaemic stroke [through a patent foramen ovale (PFO)]. Thrombi in the left atrium and its appendage or ventricle form in the context of atrial fibrillation and infarction, respectively. Furthermore, thrombi can form on native or prosthetic aortic valves, within the aorta (in particular at sites of ulcers, aortic dissection, and abdominal aneurysms), and in cerebral and peripheral arteries causing stroke and critical limb ischaemia, respectively. Finally, thrombotic occlusion may occur in arteries supplying vital organs such the heart, brain, kidney, and extremities. Thrombus formation and embolization can be managed with anticoagulants and devices depending on where they form and embolize and on patient characteristics. Vitamin K antagonists are preferred in patients with mechanical valves, while novel oral anticoagulants are first choice in most other cardiovascular conditions, in particular venous thromboembolism and atrial fibrillation. As anticoagulants are associated with a risk of bleeding, devices such as occluders of a PFO or the left atrial appendage are preferred in patients with an increased bleeding risk. Platelet inhibitors such as aspirin and/or P2Y12 antagonists are preferred in the secondary prevention of coronary artery disease, stroke, and peripheral artery disease either alone or in combination depending on the clinical condition. A differential and personalized use of anticoagulants, platelet inhibitors, and devices is recommended and reviewed in this article.

Different glomerular filtration rate estimating formula for prescribing DOACs in oldest patients: appropriate dosage and bleeding risk. Post hoc analysis of a prospective cohort

Background

Direct oral anticoagulants (DOACs) pharmacokinetics depends on estimated glomerular filtration rate (eGFR), whose estimation is crucial for optimal risk/benefit balance.

Aims

To assess the concordance among different eGFR formulas and the potential impact on DOACs prescription appropriateness and bleeding risk in oldest hospitalized patients.

Methods

Post hoc analysis of a single-centre prospective cohort study. eGFR was calculated by creatinine-based (MDRD, CKD-EPI_Cr, BIS₁) and creatinine–cystatin-C-based (CKD-EPI_Comb and BIS₂) formulas. Patients were stratified according to eGFR [severely depressed (SD) 15–29; moderately depressed (MD) 30–49; preserved/mildly depressed (PMD): ≥ 50 ml/min/1.73 m²]. Concordance between the different equations was assessed by Cohen’s kappa coefficient.

Results

Among AF patients, 841 (59.2% women, mean age 85.9 ± 6.5 years) received DOACs. By CKD-EPI_Cr equation, 135 patients were allocated in the SD, 255 in the MD and 451 in the PMD group. The concordance was excellent only between BIS 2 and CKD-EPI_Comb and MDRD and CKD-EPI_Cr, while was worse (from good to poor) between the other formulas. Indeed, by adding cystatin-C almost over 1/3 of the patients were reallocated to a worse eGFR class. Bleeding prevalence increased by 2–3% in patients with discordant eGFR between formulas, reallocated to a worse chronic kidney disease (CKD) stage, although without reaching statistical significance. CKD-EPI_Comb resulted the best predictor of bleeding events (AUROC 0.71, p = 0.03).

Discussion

This study highlights the variability in CKD staging according to different eGFR formulas, potentially determining inappropriate DOACs dosing. Although the cystatin-C derived CKDEPI_Comb equation is the most accurate for stratifying patients, BIS₁ may represent a reliable alternative.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01986-w.

Comparative Safety and Effectiveness of Apixaban vs. Warfarin in Oral Anticoagulant-Naïve Japanese Patients With Non-Valvular Atrial Fibrillation - A Retrospective Chart Review Study

BACKGROUND

The risk of bleeding and stroke/systemic embolism (SE) events associated with apixaban vs. warfarin among oral anticoagulant-naïve Japanese patients with non-valvular atrial fibrillation (NVAF) has not been well studied in daily clinical practice.

METHODS AND RESULTS

Clinical data for 12,090 patients were retrospectively extracted from the medical records of patients with NVAF (aged ≥20 years, creatinine clearance [CrCl] ≥15 mL/min) newly initiated to apixaban or warfarin treatment between January 1, 2010, and December 31, 2017, at 315 general practitioner clinics and 87 hospitals across Japan. After applying propensity score matching, patient characteristics were well-balanced between the apixaban and warfarin groups (4,523 patients each). The incidence rate (per 100 person-years) of major bleeding was lower in the apixaban vs. warfarin group (1.17 vs. 1.64; hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.54-0.93; P=0.01), as was that of stroke/SE (1.14 vs. 1.73; HR, 0.65; 95% CI, 0.50-0.85; P<0.01). When patients were stratified by CrCl (≥50 mL/min and <50 mL/min), the P value for interaction was not statistically significant between subgroups (P=0.31 for major bleeding and P=0.32 for stroke/SE).

CONCLUSIONS

The benefit of apixaban over warfarin for the reduction in risk of major bleeding and stroke/SE could be generalizable to daily clinical practice and to patients with reduced renal function.

Development and validation of an ultra-high performance liquid chromatography with tandem mass spectrometry method for the simultaneous quantification of direct oral anticoagulants in human plasma

Direct oral anticoagulants are widely used to treat and prevent thromboembolic disorders. With rising clinical application, monitoring concentrations of direct oral anticoagulants are necessary in certain clinical conditions. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometry method was developed for the simultaneous determination of dabigatran etexilate, dabigatran, rivaroxaban, edoxaban, and apixaban, in human plasma. Protein precipitation with methanol was performed for sample preparation. The direct oral anticoagulants and internal standards were separated under gradient conditions using a C18 column, at an analytical run time of 8 min. The mobile phase was composed of 0.1% (v/v) formic acid in water (solvent A) and 0.1% (v/v) formic acid in acetonitrile (solvent B) at a flow rate of 0.3 mL/min. Mass detection was performed in multiple reaction monitoring using positive ionization mode. The method was validated over a range of 1.0-500 ng/mL for dabigatran etexilate, 0.1-500 ng/mL for dabigatran, and 0.5-500 ng/mL for edoxaban, rivaroxaban, and apixaban. The method detection limits of five analytes were in the range of 0.05-0.5 ng/mL. The lower limits of quantification of five analytes ranged from 0.1 to 1 ng/mL. The linearity (r² values) was higher than 0.997. The accuracy of the low, medium, and high quality control samples were between 85.9 and 114%, and intra- and inter-day precision were below 9.47%. This validated method was successfully used to determine the plasma concentrations of rivaroxaban in 32 patients, and of dabigatran etexilate and dabigatran in 1 patient.

[Management of bleeding in patients on antithrombotic therapy]

BACKGROUND

Severe bleeding under antithrombotic therapy is common and challenging in intensive care medicine; on the one hand, rapid bleeding control must be achieved and, on the other hand, thromboembolic complications must be avoided.

AIMS

The paper will provide a brief overview of direct oral anticoagulants, therapeutic options and precise instructions for dealing with severe bleeding.

RESULTS

In addition to general measures in direct oral anticoagulant (DOAC)-associated major bleeding, prothrombin complex concentrate (PCC), idarucizumab and andexanet alfa are available as specific antidote therapy. In case of bleeding under heparin therapy, protamine sulfate is available as a possible antidote.

CONCLUSIONS

In particular, the importance of andexanet alfa in the treatment of factor Xa inhibitor-associated bleeding requires further investigation.

A Review of Direct Oral Anticoagulants in Patients With Stage 5 or End-Stage Kidney Disease

OBJECTIVE

To evaluate the role of oral anticoagulation in patients with stage 5 chronic kidney disease (CKD-5) or end-stage kidney disease (ESKD).

DATA SOURCES

A literature search of PubMed (January 2000 to July 1, 2021), the Cochrane Library, and Google Scholar databases (through April 1, 2021) was performed with keywords DOAC (direct-acting oral anticoagulant) OR NOAC or dabigatran OR rivaroxaban OR apixaban OR edoxaban AND end-stage kidney disease combined with atrial fibrillation (AF) or venous thromboembolism (VTE) OR pulmonary embolism OR deep-vein thrombosis.

STUDY SELECTION AND DATA EXTRACTION

Case-control, cohort, and randomized controlled trials comparing DOACs to an active control for AF or VTE in patients with CKD-5 or ESKD and reporting outcomes of stroke, recurrent thromboembolism, or major bleeding were included.

DATA SYNTHESIS

Nine studies were included. Efficacy data supporting routine use of warfarin or DOACs in CKD-5 or ESKD are limited. Rivaroxaban and apixaban may provide enhanced safety compared to warfarin in patients with AF. Data for VTE are limited to 1 retrospective study.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Because of the paucity of rigorous, prospective studies in CKD-5 or ESKD, OACs should not be broadly used in this population. It is clear that data regarding efficacy of DOACs cannot be reliably and safely extrapolated from the non-ESKD population. Therefore, use of OACs in this population should be individualized.

CONCLUSIONS

If OACs for stroke prevention with AF are deemed necessary, apixaban or rivaroxaban can be considered. DOACs cannot currently be recommended over warfarin in patients with CKD-5 or ESKD and VTE.

Review Article: Gastrointestinal Bleeding Risk with Direct Oral Anticoagulants

PURPOSE

Although direct oral anticoagulants (DOACs) are associated with an overall favourable safety profile, the risk of gastrointestinal bleeding with DOACs compared with vitamin K antagonists (VKAs) remains controversial. Accordingly, we aimed to provide a focused overview of the risk of gastrointestinal bleeding associated with dabigatran, rivaroxaban, apixaban and edoxaban and its management.

METHODS

We reviewed published studies reporting on DOACs with gastrointestinal bleeding as an outcome, including randomised controlled trials (RCTs), retrospective database studies and large-scale prospective cohort studies.

RESULTS

Cumulative evidence confirms no notable difference in major gastrointestinal bleeding risk between DOACs and VKAs. Moreover, gastrointestinal bleeding in DOAC-treated patients seems less severe and requires less intensive management. The main cause of upper gastrointestinal bleeding in DOAC-treated patients appears to be gastroduodenal ulcers, whereas lower gastrointestinal bleedings are mainly due to diverticula followed by angiodysplasia and haemorrhoids. The lack of head-to-head RCTs with DOACs precludes drawing conclusions on the DOAC with the lowest gastrointestinal bleeding risk. Prescribing physicians should be aware of risk factors for DOAC-related gastrointestinal bleeding (e.g. age > 65, heavy alcohol use, uncontrolled hypertension, hepatic or renal dysfunction, active cancer, anaemia) and adopt preventive measures accordingly. Management of DOAC-associated major gastrointestinal bleeding involves temporary discontinuation of the DOAC, investigation of the bleeding source and treatment of bleeding with fluid resuscitation combined with transfusion and endoscopic haemostasis.

CONCLUSION

DOACs as a class do not increase the risk of major gastrointestinal bleeding compared to VKAs, which supports their continued use for different anticoagulant indications.

Thromboembolic and Hemorrhagic Outcomes in the Direct Oral Anticoagulant Trials Across the Spectrum of Kidney Function

Chronic kidney disease is a common comorbidity among patients taking direct-acting oral anticoagulants (DOACs). Herein, we evaluate the influence of kidney function on stroke or systemic embolism (SEE), hemorrhage, and composite end points (stroke/SEE/hemorrhage/death and stroke/SEE/death) among patients on DOACs and warfarin. Baseline kidney function was categorized as glomerular filtration rate (GFR) ≥ 60 (reference), 45-59, and < 45mL/min/1.73 m2 for participants in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) (n = 18,049), Apixaban for Reduction in Stroke and Other Thromboembolic Events (ARISTOTLE) (n = 18,187), and The Effective Anticoagulation with Factor Xa Next Generation in AF (ENGAGE AF) (n = 20,798) trials. Incidence of events was compared across GFR categories. Hazard ratios for events were estimated using Cox regression using intention-to-treat analysis adjusting for known predictors. A large proportion of participants had GFR < 60 (25-29% had 45 ≤ GFR < 60 and 9.5-12.6% with GFR < 45). Compared with patients with GFR ≥ 60, warfarin users across the trials with GFR ≥ 45-59 and GFR < 45 had a higher incidence of hemorrhage (P values < 0.0001) and warfarin users in the ARISTOTLE and ENGAGE trials had higher incidence of stroke/SEE (P values ≤ 0.05). Compared with patients with GFR ≥ 60, dabigatran users with GFR ≥ 45-59 and GFR < 45 had a higher incidence of stroke/SEE (P ≤ 0.02), hemorrhage (P < 0.001), and both composite end points (P < 0.0001). Compared with patients with GFR ≥ 60, apixaban and edoxaban users with GFR ≥ 45-59 and GFR < 45 had a higher incidence of hemorrhage (P values ≤ 0.05) and composite end points (P values ≤ 0.05). After adjustment, compared with patients with GFR ≥ 60, warfarin users with GFR < 60 in the ARISTOTLE and RE-LY trials had a higher risk of hemorrhage (P < 0.05), as did dabigatran (P < 0.001) and edoxaban (P ≤ 0.005) users, while apixaban users did not exhibit an increased risk (P = 0.08 GFR ≥ 45-59; P = 0.71 GFR < 45). Kidney function significantly influences the safety and efficacy of oral anticoagulants.

Unmet Clinical Needs in Elderly Patients Receiving Direct Oral Anticoagulants for Stroke Prevention in Non-valvular Atrial Fibrillation

Vitamin K antagonists have been used for many years as the treatment of choice for long-term oral anticoagulation in patients with non-valvular atrial fibrillation. Unfortunately, the use of those drugs in the real-world setting, particularly among elderly patients, is suboptimal because of their limitations in management. Therefore, many patients were not adequately anticoagulated. Direct oral anticoagulants have been demonstrated to overcome almost all the limitations derived from the use of vitamin K antagonists. Direct oral anticoagulants are at least as effective as vitamin K antagonists in preventing thromboembolic events in patients with non-valvular atrial fibrillation and safer in reducing the risk of intracranial haemorrhage and all-cause mortality. However, as a result of the strict inclusion and exclusion criteria applied to patients, data coming from randomized controlled trials might not apply to the general population. Furthermore, elderly patients were scarcely represented in randomized controlled trials with direct oral anticoagulants. Therefore in elderly patients with non-valvular atrial fibrillation, unmet clinical needs still exist. This review article highlights some of them and provides potential answers based on the results coming from randomized clinical trials, real-world data, and the authors' clinical experience.

Performance Characteristics of DOAC Dipstick in Determining Direct Oral Anticoagulants in Urine

Testing for direct oral anticoagulants (DOACs) in patient urine may facilitate medical treatment decisions. The aim of this study was to investigate interobserver variability by 2 independent observers compared to laboratory staff in the visual interpretation of factor Xa (DXI) and thrombin inhibitors (DTI) using the DOAC Dipstick test. We also examined whether test pads reacted to other anticoagulants and abnormal urine colors. The colors of the DOAC Dipstick direct factor Xa inhibitor and thrombin inhibitor pads were interpreted with 100% accuracy (95% confidence interval 0.862 to 1.000) for urine samples from persons treated with apixaban (n = 26), rivaroxaban (n = 24), and dabigatran (n = 29) and without anticoagulant therapy (n = 29). The factor Xa and thrombin inhibitor pads did not interact with heparin, nadroparin, fondaparinux, or coumadin. One µg/mL r-Hirudin and 6 µg/mL argatroban interacted with the DTI pad; however, this is unlikely to cause clinical problems because dabigatran is unlikely to be administered together with r-Hirudin and argatroban in clinical circumstances. Abnormal urine color was reliably detected by the urine color pad, so can prevent false interpretation of the DOAC Dipstick pad colors. In conclusion, we have demonstrated that interobserver variability when interpreting the DOAC Dipstick test strip is low and that factor Xa and thrombin inhibitor pads do not react to other anticoagulants such as heparins and coumadin. R-Hirudin and argatroban can be detected by the thrombin inhibitor pad and abnormal urine colors can be detected by the urine color pad to prevent false interpretation of the results in patient urine samples.

Effect of Disease State on the Pharmacokinetics of Bedaquiline in Renal-Impaired and Diabetic Rats

Bedaquiline (TMC-207) is a key anti-tubercular drug to fight against multidrug resistance tuberculosis. Little information is available till date on the impact of any disease state toward its pharmacokinetic behavior. The present research work aimed to investigate the effect of renal impairment and diabetes mellitus on the oral pharmacokinetics of bedaquiline in the rat model. Renal impairment and diabetes mellitus were induced in the Wistar rat model separately using cisplatin and streptozotocin, respectively, and thereafter, an oral pharmacokinetic study of bedaquiline was carried out in the individual disease models as well as in the normal rat model. Pharmacokinetic parameters of bedaquiline were not altered markedly in cisplatin-induced renal-impaired rats compared to normal rats except an area under the curve (AUC) for plasma concentration of bedaquiline in the experimental time frame (AUC_0-t ) reduced to 3477 ± 228 from 4984 ± 1174 ng h/mL, respectively. Maximum plasma concentrations of bedaquiline (259 ± 77 ng/mL), AUC_0-t (3112 ± 1046 ng h/mL), and AUC_0-∞ (3673 ± 1493 ng h/mL) were significantly reduced along with an increase in the clearance of bedaquiline (3.1 ± 1.1 L/h/kg) in the case of streptozotocin-induced diabetic rats compared to respective pharmacokinetic parameters of bedaquiline (482 ± 170 ng/mL, 4984 ± 1174 ng h/mL, and 6137 ± 1542 ng h/mL) in the normal rats. Preclinical findings suggest that dose adjustment of bedaquiline is required in the diabetes mellitus condition to prevent the therapeutic failure of bedaquiline treatment, but clinical exploration is needed to establish the fact. It is the first report for the consequence of renal impairment and diabetes mellitus on the pharmacokinetics of bedaquiline in the preclinical model.

Direct Oral Anticoagulants in Patients with Atrial Fibrillation and Renal Dysfunction

Atrial fibrillation and renal dysfunction often coexist, each disorder may predispose to the other and contribute to worsening prognosis. Both atrial fibrillation and chronic kidney disease are associated with increased risk of stroke and thromboembolic complications. Oral anticoagulation for stroke prevention is therefore recommended in patients with atrial fibrillation and decreased renal function. Each direct oral anticoagulant has unique pharmacologic properties of which clinician should be aware to optimally manage patients. The doses of direct oral anticoagulants require adjustment for renal function. There is debate regarding which equation, the Chronic Kidney Disease Epidemiology (CKD-EPI) equation vs. the Cockcroft-Gault equation, should be used to estimate glomerular filtration rate in patients with atrial fibrillation treated with direct oral anticoagulants. Our review tries to find arguments for benefit of direct oral anticoagulants in patients with renal dysfunction.

Direct Oral Anticoagulant Use in Special Populations: Elderly, Obesity, and Renal Failure

PURPOSE OF REVIEW

The purpose of this review is to examine the safety and effectiveness of direct oral anticoagulants and provide recommendations for the treatment of venous thromboembolism and atrial fibrillation in obese patients, elderly patients, and patients with chronic kidney disease.

RECENT FINDINGS

Multiple retrospective cohort studies have shown no difference in bleeding, stroke, or venous thromboembolism outcomes between DOACs and warfarin in patients who are obese, elderly, or those with chronic kidney disease or on dialysis. Some studies have shown that DOACs have a lower bleeding risk than warfarin in these populations. DOACs may be a safe and effective alternative to warfarin for the prevention of stroke in atrial fibrillation patients who are obese, elderly, or those with chronic kidney disease or on dialysis. Apixaban may improve clinical outcomes by lowering the risk of bleeding versus warfarin. DOACs may also be an effective and safe alternative to warfarin for the treatment of venous thromboembolism in obese patients; however, additional studies are needed to assess their use in elderly patients and those with CKD.

Real-World Data on Characteristics and Management of Community Patients Receiving Anticoagulation Therapy Who Presented with Acute Bleeding to the Emergency Department at a Regional Australian Hospital: A Prospective Observational Study

OBJECTIVE

To study patients receiving anticoagulants with or without antiplatelet therapy presenting at a regional Australian hospital with bleeding. The main aims are to explore: (1) patients' characteristics and management provided; (2) association between the type of anticoagulant and antiplatelet agent used and the requirement of reversal; (3) and the length of hospital stay (LoS) in conjunction with bleeding episode and management.

METHODS

A prospective cross-sectional review of medical records of all patients who presented at a tertiary referral centre with bleeding while receiving anticoagulation therapy between January 2016 and June 2018. Data included: patients, demographics, investigations (kidney and liver function tests, coagulation profile, FBC), LoS, bleeding site, type of and reason for anticoagulation therapy, and management provided. Data analysis included descriptive statistics, χ2 association, and regression models.

RESULTS

Among the 144 eligible patients, 75 (52.1%) were male, and the mean age was 76 years (SD=11.1). Gastrointestinal tract bleeding was the most common (n=48, 33.3%), followed by epistaxis (n=32, 22.2%). Atrial fibrillation was the commonest reason for anticoagulation therapy (n=65, 45.1%). Warfarin was commonly used (n=74, 51.4%), followed by aspirin (n=29, 20.1%), rivaroxaban (n=26, 18.1%), and apixaban (n=12, 8.3%). The majority had increased blood urea nitrogen (n=67, 46.5%), while 58 (40.3%) had an elevated serum creatinine level, and 59 (41.0%) had a mild reduction in eGFR. Thirty-five of the warfarinised patients (47.3%) had an INR above their condition's target range despite normal liver function. Severe anaemia (Hb<80g/L) was reported in 88 patients (61.1%). DOACs were associated with a reduced likelihood of receiving reversal (B= -1.7, P=<.001), and with a shorter LoS (B= -4.1, P=.046) when compared with warfarin, LMWH, and antiplatelet therapy.

CONCLUSION

Warfarin use was common among patients who presented with acute bleeding, and the INR in many warfarinised patients exceeded the target for their condition. DOACs were associated with a reduced likelihood of receiving reversal and a shorter LoS than warfarin, LMWH, which might support a broader application of DOACs into community practice.

How should we manage hip fracture patients on direct oral anticoagulants?

OBJECTIVE

Currently, there are no national protocols in place for managing hip fracture patients on direct oral anticoagulants (DOACs). Hence, various local management protocols exist. We compared three different local protocols and a control group to assess blood loss and time delay to theatre.

METHODS

Sequential data were collected for 120 hip fracture patients in four groups; wait 24 hours from last dose, wait 48 hours, perform DOAC levels and control.

RESULTS

DOAC use in our hip fracture patients was 14%. Median haemoglobin (Hb) drop between the three protocol groups showed no significant difference (13.5, 21.5 and 16.0 g/L) (Kruskal-Wallis, p=0.9). Median Hb drop in the control group was 16.0 g/L versus 17.5 g/L in the protocol groups combined (Mann Whitney-U, p=0.7). Average Hb drop in the control group was 19.2 g/L and in the protocol groups was 22.1 g/L; a 15% greater blood loss with DOACs. The frequency distribution of blood loss was different between the control and protocol groups, but not between the protocol groups. The highest Hb drop in the control group was 3.4 g/L, while in the protocol groups, it was 7.8 g/L. Median Hb on arrival to hospital was higher in the control group (124 g/L) compared with the three protocol groups (87 g/L) (t-test p<0.0001). Transfusion rates of up to 40% were observed within the DOAC groups compared with zero in the control group.Median time to theatre between the three protocol groups was significantly different at 17.5, 53.3 and 22.5 hours, respectively (Kruskal-Wallis, p<0.0001).

CONCLUSION

DOACs caused increased bleeding and delays to theatre in hip fracture patients, however the largest Hb difference was already apparent on arrival. Subsequent blood loss was minimal on average; a few patients bled heavily. Prolonged waiting made no significant difference to blood loss, but caused delay to theatre leading to financial losses from best practice tariff.

The relationship between DOAC levels and clinical outcomes: The measures tell the tale

Direct oral anticoagulants (DOACs) are increasingly used for treatment and prevention of thromboembolic diseases, used in fixed dose regimens. Although their safety and efficacy profiles are considered optimal, clinical events still occur. Given that anticoagulation treatment is a delicate balance between clotting and bleeding, it is possible that an optimal target spot exists where the effect of anticoagulation achieves both the lowest possible risk of bleeding and thrombosis. Other currently available anticoagulants (ie, vitamin K antagonists and heparins) provide important clues for this. If such a target spot exists, tailored DOAC therapy may further benefit patients. This opinion article summarizes the current available evidence that suggests that such a tailored strategy could work. It also describes research suggestions for conducting studies in patient populations such as patients with extremes of body weight or impaired kidney function to evaluate whether tailored treatment with DOACs could lead to better patient outcomes.

Efficacy and safety of direct oral anticoagulants for secondary prevention of cancer associated thrombosis: a meta-analysis of randomized controlled trials

Direct oral anticoagulants (DOACs) may be good alternatives to low molecular weight heparin (LMWH) or vitamin K antagonists (VKA) for treatment of cancer associated thrombosis (CAT). We conducted a meta-analysis of ten randomized clinical trials to evaluate the efficacy and safety of DOACs in patients with CAT. All had study populations composed in entirety or in part of patients with CAT. The primary outcome (efficacy) was recurrent VTE and the secondary outcomes (safety outcomes) included major bleeding, clinically relevant non-major bleeding (CRNMB), and all bleeding (major bleeding + CRNMB). Participants treated with DOACs had lower risk of recurrent VTE, overall (RR 0.63; 95% CI 0.51-0.79; p < 0.0001), compared to LMWH (RR 0.57; 95% CI 0.40-0.83; p = 0.003), but not compared to VKA (RR 0.69; 95% CI 0.44-1.06; p = 0.09). Compared to LMWH, DOACs showed no difference in major bleeding risk (RR 1.31; 95% CI 0.78-2.18; p = 0.31), though had higher risk of CRNMB (RR 1.60; 95% CI 1.13-2.26; p = 0.008) and all bleeding (RR 1.49; 95% CI 1.10-2.01; p = 0.010). These results indicate that DOACs are more effective than LMWH for prevention of recurrent VTE with CAT though carry an increased risk for non-major bleeding compared to standard of care, LMWH.

Direct-acting oral anti-coagulants in dental practice: A Retrospective Observational Study (Part 1)

OBJECTIVES

The objective of this retrospective observational study was to determine the incidence of direct-acting oral anti-coagulant (DOA) use in patients receiving invasive dental procedures. The secondary objective was to investigate the precautionary measures implemented and the post/intraoperative complications associated with DOA use.

METHODS

Electronic record database, Axium, was retrospectively reviewed, and patients using NGOA and treated between 2010 and 2017 were identified. Charts of patients who underwent invasive dental procedures were further reviewed to investigate the preoperative/intraoperative precautionary measures taken and identify any intraoperative/postoperative complications.

RESULTS

A total of 130 patients were identified, with their annual number steadily rising from 12 in 2011 to 52 in 2016. Among those, 64 patients (49.23%) underwent invasive dental procedures. Pretreatment medical consults were obtained in all patients undergoing invasive procedures; however, only 7 (10.94%) were instructed to discontinue their DOA. Preoperative laboratory testing was obtained for two patients. Intraoperatively, 34 (53.13%) cases of excessive bleeding were reported, all were locally controlled with hemostatic agents. Only 4 instances of postoperative complications were documented.

CONCLUSIONS

Despite the rise in the use of DOA, there is no consistent pattern for preoperative laboratory testing and DOA discontinuations. Expert consensus may be of great importance to develop practice guidelines.

Management of Outpatient Warfarin Therapy amid COVID-19 Pandemic: A Practical Guide

Many healthcare resources have been and continue to be allocated to the management of patients with COVID-19. Therefore, the ongoing care of patients receiving oral anticoagulation with warfarin is likely to be compromised amid this unprecedented crisis. This article discusses a stepwise algorithm for the management of outpatient warfarin therapy. Alternative management strategies are presented and discussed, including alternative pharmacological therapy options and self-monitoring. Our algorithm aims to help clinicians safely optimize the treatment of patients requiring anticoagulation therapy in the context of the global response to the current pandemic.

Effect of Sex, Use of Pantoprazole and Polymorphisms in SLC22A1, ABCB1, CES1, CYP3A5 and CYP2D6 on the Pharmacokinetics and Safety of Dabigatran

INTRODUCTION

Dabigatran is a direct oral anticoagulant (DOAC) used for the treatment of several thrombotic conditions. To date, very few pharmacogenetic studies on dabigatran were published. We aimed to investigate the influence of 59 polymorphisms in 15 genes (including CES1, UGT and CYP that encode enzymes and ABCB1 and SLC that encode transporters), concomitant treatment with pantoprazole and demographic characteristics (including sex or race) on dabigatran pharmacokinetics and safety.

METHODS

This was a candidate gene pharmacogenetic study. The study population comprised 107 volunteers enrolled in two dabigatran bioequivalence clinical trials; they were genotyped with a ThermoFisher QuantStudio 12K Flex OpenArray instrument. SPSS software v.21 was used for statistical analysis.

RESULTS

Women showed a higher exposure to dabigatran compared to men. The concomitant treatment with pantoprazole was associated with a decreased exposure to the drug. CYP2D6 poor metabolizers (PMs) were related to lower clearance (Cl/F) (p = 0.049) and a tendency was observed towards higher area under the curve (AUC), maximum concentration (C_max) and to lower volume of distribution (V_d/F) (p < 0.10). SLC22A1 haplotype was related to pharmacokinetic variability (p < 0.05). The remaining genes (including CYP, UGT1A1 and ABCB1) had no effect on dabigatran pharmacokinetics (p > 0.10). Women showed more adverse drug reactions (ADR) compared to men (0.40 ± 0.68 vs 0.15 ± 0.41 ADR per person, p = 0.03) and SLC22A1 mutant haplotype was related to a lower risk of nausea (p = 0.02).

CONCLUSION

Sex, concomitant use of pantoprazole and SLC22A1, CYP2D6 and CYP3A5 polymorphism had an effect on dabigatran pharmacokinetics and safety. Previously published pharmacogenetic predictors, namely CES1 or ABCB1 polymorphisms, had no effect on pharmacokinetics and safety. This study is of interest as it increases the scarce pharmacogenetic information on dabigatran.

Periprocedural Management of Oral Anticoagulation

Decisions surrounding periprocedural anticoagulation management must balance thromboembolic and procedural bleed risk. The interruption of both warfarin and DOACs requires consideration of anticoagulant pharmacokinetics, procedural bleed risk and patient characteristics. There is a diminishing role for periprocedural bridging LMWH overall and no role for bridging LMWH for the procedural interruption of DOACs. A clinical approach to perioperative DOAC management based on operative bleeding risk and renal function is safe and effective, and at present, is preferred over preprocedural DOAC levels testing. Clear communication of the anticoagulation interruption plan to both the patient and the patient's care team is essential.

Design, synthesis, and biological evaluation of 4-methoxy-3-arylamido-N-(substitutedphenyl)benzamide derivatives as potential antiplatelet agents

A series of 4-methoxy-3-arylamido-N-(substitutedphenyl)benzamides 6a-u were designed according to the splicing principle of structural design in the medicinal chemistry theory and were synthesized in five steps: nitration, acylation, ammoniation, reduction, and secondary ammoniation. The structures of the target compounds were characterized and verified by infrared, ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and electron spray ionization spectroscopy. Their in vitro antiplatelet aggregation activities induced by adenosine diphosphate (ADP) or arachidonic acid (AA) were assessed by Born's method. The biological evaluation revealed that all compounds exhibited certain levels of activities in both of the antiplatelet aggregation assays; compounds 6c (IC₅₀  = 3.84 μM) and 6f (IC₅₀  = 3.12 μM) displayed the strongest antiplatelet aggregation activities in the ADP-induced and AA-induced assay, separately. Moreover, compounds that had stronger activities were chosen for cell toxicity testing via the cell counting kit-8 assay. The results indicated that none of the compounds had obvious cell toxicity against L929 cells at the doses of 10 and 20 μM. It is worth pointing out that compound 6c showed the highest antiplatelet activity and the lowest cell toxicity. In general, 4-methoxy-3-arylamido-N-(substitutedphenyl)benzamides have the potential to become a kind of safer and more effective antiplatelet agents.

Type 2 Diabetes, Atrial Fibrillation, and Direct Oral Anticoagulation

Type 2 diabetes (T2D) is an independent risk factor of stroke and systemic embolism in patients with atrial fibrillation (AF), and T2D patients with AF-associated stroke seem to have worse clinical outcome and higher risk of unfavorable clinical course compared to individuals without this metabolic disorder. Long-term anticoagulation is indicated in majority of T2D patients with AF to prevent adverse AF-associated embolic events. Direct oral anticoagulants (DOACs), direct oral thrombin inhibitor dabigatran, and direct oral factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban, have emerged as a preferred choice for long-term prevention of stroke in AF patients offering potent and predictable anticoagulation and a favorable pharmacology with low risk of interactions. This article reviews the current data regarding the use of DOACs in individuals with T2D and AF.

Clinical outcomes and treatment patterns among Medicare patients with nonvalvular atrial fibrillation (NVAF) and chronic kidney disease

Background

Patients with nonvalvular atrial fibrillation (NVAF) and chronic kidney disease (CKD) have increased risk of adverse outcomes. This study evaluated treatment with oral anticoagulants and outcomes in elderly NVAF patients with CKD.

Methods

Retrospective observational cohort study of US Medicare fee-for-service patients aged ≥66 years with comorbid CKD (advanced: Stage 4 and higher; less advanced: Stages 1–3) and a new NVAF diagnoses from 2011–2013. All-cause mortality, stroke, major bleeding, and myocardial infarction rates were estimated for 1 year post-NVAF diagnosis. Associations between CKD stage and outcomes were evaluated with multivariate-adjusted Cox regression. We assessed oral anticoagulant (OAC) receipt within 90 days post-NVAF diagnosis and associations between OAC receipt and outcomes.

Results

There were 198,380 eligible patients (79,681 with advanced CKD). After adjustment for age, gender, and comorbidities, advanced CKD was associated with increased mortality (Stage 5 HR 1.47; 95% CI 1.42–1.52), MI (HR 1.48; 95% CI 1.33–1.64), stroke (HR 1.23; 95% CI 1.11–1.37) and major bleed (HR 1.44; 95% CI 1.36–1.53) risks. Among Medicare Part D enrollees who survived ≥90 days post-NVAF diagnosis, 65–71% received no OACs in the first 90 days. Those receiving warfarin (HR 0.73; 95% CI 0.71–0.75) or DOACs (HR 0.52; 95% CI 0.49–0.56) within the first 90 days had reduced mortality in the period 90 days to 1 year following NVAF diagnosis compared to those without.

Conclusion

Elderly NVAF patients with advanced CKD (Stage 4 or higher) had higher mortality risks and serious clinical outcomes than those with less advanced CKD (Stage 1–3). OAC use was low across all CKD stages, but was associated with a lower mortality risk than no OAC use in the first year post-NVAF diagnosis.