Impact of Polypharmacy and P-Glycoprotein- and CYP3A4-Modulating Drugs on Safety and Efficacy of Oral Anticoagulation Therapy in Patients with Atrial Fibrillation

Nonvitamin K Anticoagulants: Risk of Bleeding When Interacting With Other Medications: A Cohort Study From Medicare

INTRODUCTION

Patients on nonvitamin K antagonist (NVKA) are usually taking other drugs. Potential interaction may increase the gastrointestinal (GI) bleeding risk associated with NVKA.

METHODS

Observational cohort study using Medicare data from 2017 to 2020. Participants receiving a NVKA were included. A concomitant overlapping period while on NVKA was assessed for nonsteroidal anti-inflammatory drugs (NSAIDS), selective serotonin reuptake inhibitors (SSRI), antiplatelets, glucocorticoids, aspirin and proton pump inhibitors (PPI). A logistic regression predicting either any bleeding or GI bleeding was conducted estimating the odds ratio (OR) and 95% confidence interval (CI).

RESULTS

A total of 102 531 people on NVKA with mean age 77 years (SD = 9.8) and 55% females (N = 56 671) were included. Previous history of GI bleeding occurred in 2 908 (2.8%) participants, concomitant exposure to PPI occurred in 38 713 (38%), SSRI in 16 487 (16%), clopidogrel in 15 795 (15.4%), NSAIDs in 13 715 (13.4%) and glucocorticoids in 13 715 (13.4%). Risk for any bleeding was shown for clopidogrel (OR: 1.37, 95% CI: 1.30, 1.44), prasugrel/ticagrelor (OR: 1.36, 95% CI: 1.18, 1.58), glucocorticoids (OR: 1.26, 95% CI: 1.19, 1.34), and SSRIs (OR: 1.13, 95% CI: 1.07, 1.19). GI bleeding risk was shown for clopidogrel (OR: 1.44, 95% CI: 1.34, 1.55), prasugrel/ticagrelor (OR: 1.47, 95% CI: 1.20, 1.79), SSRIs (OR: 1.09, 95% CI: 1.01, 1.17) and glucocorticoids (OR: 1.33, 95% CI: 1.23, 1.44). PPI use was correlated with both NSAID (r = 0.07, p ≤ 0.0001) and SSRI use (r = 0.09, p ≤ 0.0001).

CONCLUSION

NVKA concomitantly taken with antiplatelets, glucocorticoids, and SSRIs showed an increased risk for any bleeding and GI bleeding.

Clinical Implications of Co-administering Apixaban with Key Interacting Medications

With many available data sources, clinicians need to consider the benefit-risk profile of individual anticoagulants when balancing the need for anticoagulation, including evaluating the risks in patients with comorbidities and potential drug-drug interactions. This narrative review presents clinical data across multiple phases of drug development for the use of apixaban, a selective factor Xa inhibitor, when taken concomitantly with other agents, and evaluates the benefit-risk profile of apixaban with these interacting medications. Key subgroup analyses from the phase 3 ARISTOTLE trial (NCT00412984) are presented using data from patients who received either concomitant inhibitors or inducers of cytochrome P450 3A4 and/or P‑glycoprotein. We also review the available evidence for the use of apixaban in patients with cancer-associated thromboembolism, as well as the use of apixaban in patients with COVID-19.

Effect of Clarithromycin, a Strong CYP3A and P-glycoprotein Inhibitor, on the Pharmacokinetics of Edoxaban in Healthy Volunteers and the Evaluation of the Drug Interaction with Other Oral Factor Xa Inhibitors by a Microdose Cocktail Approach

PURPOSE

We assessed the differential effect of clarithromycin, a strong inhibitor of cytochrome P450 (CYP) 3A4 and P-glycoprotein, on the pharmacokinetics of a regular dose of edoxaban and on a microdose cocktail of factor Xa inhibitors (FXaI). Concurrently, CYP3A activity was determined with a midazolam microdose.

METHODS

In an open-label fixed-sequence trial in 12 healthy volunteers, the pharmacokinetics of a microdosed FXaI cocktail (μ-FXaI; 25 μg apixaban, 50 μg edoxaban, and 25 μg rivaroxaban) and of 60 mg edoxaban before and during clarithromycin (2 x 500 mg/d) dosed to steady-state was evaluated. Plasma concentrations of study drugs were quantified using validated ultra-performance liquid chromatography-tandem mass spectrometry methods.

RESULTS

Therapeutic clarithromycin doses increased the exposure of a therapeutic 60 mg dose of edoxaban with a geometric mean ratio (GMR) of the area under the plasma concentration-time curve (AUC) of 1.53 (90 % CI: 1.37-1.70; p < 0.0001). Clarithromycin also increased the GMR (90% CI) of the exposure of microdosed FXaI apixaban to 1.38 (1.26-1.51), edoxaban to 2.03 (1.84-2.24), and rivaroxaban to 1.44 (1.27-1.63). AUC changes observed for the therapeutic edoxaban dose were significantly smaller than those observed with the microdose (p < 0.001).

CONCLUSION

Clarithromycin increases FXaI exposure. However, the magnitude of this drug interaction is not expected to be clinically relevant. The edoxaban microdose overestimates the extent of the drug interaction with the therapeutic dose, whereas AUC ratios for apixaban and rivaroxaban were comparable to the interaction with therapeutic doses as reported in the literature.

TRIAL REGISTRATION

EudraCT Number: 2018-002490-22.

The Impact of Polypharmacy on the Effectiveness and Safety of Non-vitamin K Antagonist Oral Anticoagulants in Patients with Atrial Fibrillation

BACKGROUND

 Polypharmacy may affect outcomes in patients with atrial fibrillation (AF) using non-vitamin K antagonist oral anticoagulants (NOACs) or vitamin K antagonists (VKAs) due to interactions or reduced adherence, but comparative data are lacking. Therefore, the impact of polypharmacy on AF-related outcomes and benefit-risk profiles of NOACs in patients with polypharmacy were investigated.

METHODS

 AF patients initiating anticoagulation between 2013 and 2019 were included using Belgian nationwide data. Inverse probability of treatment weighted Cox regression was used to investigate outcomes.

RESULTS

 Among 254,478 AF patients, 167,847 (66.0%) used ≥5 drugs. Polypharmacy was associated with higher stroke or systemic embolism (stroke/SE) (adjusted hazard ratio [aHR]: 1.08, 95% confidence interval [CI]: 1.02-1.15), all-cause mortality (aHR: 1.45, 95% CI: 1.40-1.50), and major bleeding risks (aHR: 1.29, 95% CI: 1.23-1.35). Among patients with polypharmacy, NOACs were associated with lower stroke/SE (aHR: 0.68, 95% CI: 0.63-0.73), all-cause mortality (aHR: 0.80, 95% CI: 0.77-0.84), major bleeding (aHR: 0.92, 95% CI: 0.87-0.97), and intracranial bleeding risks (aHR: 0.77, 95% CI: 0.69-0.85), but higher gastrointestinal bleeding risks (aHR: 1.10, 95% CI: 1.01-1.19) compared to VKAs. Major bleeding risks were lower with apixaban (aHR: 0.79, 95% CI: 0.74-0.85), but nonsignificantly different with other NOACs compared to VKAs. Lower major bleeding risks were observed with dabigatran (aHR: 0.91, 95% CI: 0.85-0.97) and apixaban (aHR: 0.77, 95% CI: 0.73-0.81) compared to rivaroxaban, and with apixaban compared to dabigatran (HR: 0.83, 95% CI: 0.77-0.90) and edoxaban (HR: 0.77, 95% CI: 0.70-0.85).

CONCLUSION

 Polypharmacy was associated with increased thromboembolic, bleeding, and mortality risks in AF patients. NOACs had better benefit-risk profiles than VKAs in patients with polypharmacy.

Effectiveness and Safety of Different Oral Anticoagulants with P-glycoprotein/ CYP3A4 Inhibitors: A Network Meta-analysis

BACKGROUND

Metabolism of oral anticoagulants (OAC) is affected by P-glycoprotein (P-gp)/ CYP3A4 enzyme. However, the P-gp/CYP3A4 inhibitors are unavoidably used with OACs.

METHODS

Medline, Cochrane, and Embase were systematically searched for randomized controlled trials and cohort studies from inception till 23rd November, 2022 to assess the safety and effectiveness of OACs when concomitantly used with P-gp/CYP3A4 inhibitors. The primary outcomes were major bleeding and gastrointestinal (GI) bleeding. Secondary outcomes were stroke/systemic embolism (SE), all-cause mortality, any bleeding as well as intracranial hemorrhage (ICH). We estimated summary odds ratios (OR) with 95% credible intervals (CI) using pairwise and network meta-analysis with random effects.

RESULTS

A total of 11 studies involving 37,973 patients were included. When concomitantly used with P-pg/ CYP3A4 inhibitors, network meta-analysis indicated that dabigatran, apixaban, and edoxaban were associated with significantly lower risk of major bleeding compared to rivaroxaban, with ORs of 0.56, 0.51 and 0.48, respectively. Rivaroxaban and dabigatran were associated with a significantly increased risk of GI bleeding than warfarin, apixaban and edoxaban. Dabigatran and apixaban were linked with significantly lower risk of any bleeding compared with warfarin (ORs were 0.75 and 0.68, respectively) or rivaroxaban (ORs were 0.67 and 0.60, respectively). Apixaban (OR 0.32) and edoxaban (OR 0.35) were associated with a lower risk of ICH compared with warfarin. There was no difference between any OACs in terms of stroke/SE or all-cause mortality.

CONCLUSION

When concomitantly used with P-gp/CYP3A4 inhibitors, apixaban and edoxaban were associated with a lower risk of bleeding, though no significant difference in effectiveness was observed among all OACs.

Non-vitamin K Antagonist Oral Anticoagulants (NOACs) Versus Warfarin in Patients with Atrial Fibrillation Using P-gp and/or CYP450-Interacting Drugs: a Systematic Review and Meta-analysis

PURPOSE

Non-vitamin K antagonist oral anticoagulants (NOACs) are excreted by P-glycoprotein (P-gp) and some are metabolized by CYP450 enzymes such as CYP3A4. Although fewer drug interactions are present with NOACs, it is unclear whether NOACs should also be preferred over vitamin K antagonists (VKAs) in patients with atrial fibrillation (AF) using pharmacokinetically interacting drugs. Therefore, the benefit-risk profile of NOACs versus VKAs was investigated in AF patients treated with P-gp and/or CYP450-interacting drugs.

METHODS

Using PubMed and Embase, randomized controlled trials and observational studies on the effectiveness and safety of NOACs versus VKAs in AF patients using P-gp and/or CYP450-interacting drugs were included. A meta-analysis was performed, calculating relative risks (RR) and 95% confidence intervals (CI) with the Mantel-Haenszel method.

RESULTS

Twelve studies were included, investigating 10,793 NOAC and 10,096 VKA users treated with P-gp/CYP3A4 inhibitors, whereas no studies on P-gp and/or CYP450-inducing drugs were identified. Compared to VKAs, NOACs were associated with a borderline non-significantly lower stroke or systemic embolism (stroke/SE) risk (RR 0.85, 95%CI (0.72-1.01)), significantly lower intracranial bleeding (RR 0.47, 95%CI (0.34-0.65)) and all-cause mortality risks (RR 0.87, 95%CI (0.79-0.95), but significantly higher gastrointestinal bleeding risk (RR 1.74, 95%CI (1.06-2.86)). Among AF patients using amiodarone, NOACs were associated with significantly lower stroke/SE (RR 0.71, 95%CI (0.54-0.93)) and intracranial bleeding risks (RR 0.51, 95%CI (0.29-0.88)), but significantly higher gastrointestinal bleeding risk (RR 2.15, 95%CI (1.24-3.72)) than VKAs.

CONCLUSION

The benefit-risk profile of NOACs compared to VKAs was preserved in AF patients using P-gp/CYP3A4 inhibitors, including amiodarone.

DOAC in the treatment of cancer-associated venous thromboembolism: a retrospective cohort study beyond the guidelines

BACKGROUND

The emerging use of direct oral anticoagulants (DOAC) in the management of cancer-associated venous thromboembolism (CAT) is significantly improving therapeutic adherence and quality of life. Despite this, many conditions can restrict the therapeutic index of these drugs. For all these reasons the latest guidelines recommend the use of heparins in the treatment of CAT as the preferred treatment in some clinical settings.

OBJECTIVES

We evaluated the efficacy and the safety of DOAC, in terms of recurrent venous thromboembolism (VTE) and major bleeding (MB), as a composite primary outcome. Mortality and clinically relevant non-major bleeding (CRNMB) were evaluated as secondary outcomes.

METHODS

We performed a retrospective study on 209 patients to compare the effects of DOAC versus heparins for the treatment of CAT. 127 patients with a high bleeding risk neoplasia were enrolled.

RESULTS

A primary-outcome event occurred in 11.3% of patients treated with heparins and in 10.5% treated with DOAC (Relative Risk 0.92; 95% CI 0.42-2.01, p = 0.84). Recurrent VTE occurred in 6.1% in the heparins group and in 8.4% in the DOAC group (RR 1.37; 95% CI 0.51-3.64, p = 0.52). MB occurred in 5.2% in the heparins group and in 2.1% in the DOAC group (RR 0.40; 95% CI 0.08-1.93, p = 0.25).

CONCLUSIONS

DOAC seem to be as effective and safe as heparins in the treatment of CAT. Most bleeding events occurred in patients with high-risk bleeding neoplasms regardless of the type of anticoagulant. Considering the characteristics and satisfaction of patients using DOAC in this setting, this approach should be considered as a first choice.

Effect of Oral Anticoagulants in Atrial Fibrillation Patients with Polypharmacy: A Meta-analysis

BACKGROUND

 The aim of the present meta-analysis was to evaluate the effectiveness and safety of non-vitamin K antagonist oral anticoagulants (NOACs) versus vitamin K antagonists (VKAs) in atrial fibrillation (AF) patients with polypharmacy.

METHODS AND RESULTS

 Randomized controlled trials or observational studies reporting the data of NOACs versus VKAs among AF patients with polypharmacy were included. The search was performed in the PubMed and Embase databases up to November 2022. A total of 12 studies involving 767,544 AF patients were included. For the primary outcomes, the use of NOACs compared with VKAs was significantly associated with a reduced risk of stroke or systemic embolism in AF patients with moderate polypharmacy (hazard ratio [HR]: 0.77 [95% confidence interval [CI]: 0.69-0.86]) and severe polypharmacy (HR: 0.76 [95% CI: 0.69-0.82]), but there was no significant difference in major bleeding (moderate polypharmacy: HR: 0.87 [95% CI: 0.74-1.01]; severe polypharmacy: HR: 0.91 [95% CI: 0.79-1.06]) between the two groups. In secondary outcomes, there were no differences in the rates of ischemic stroke, all-cause death, and gastrointestinal bleeding between the NOAC- and VKA- users, but NOAC users had a reduced risk of any bleeding compared with VKA- users. Compared with VKAs, the risk of intracranial hemorrhage was reduced in NOAC- users with moderate polypharmacy but not severe polypharmacy.

CONCLUSION

 In patients with AF and polypharmacy, NOACs showed advantages over VKAs in stroke or systemic embolism and any bleeding, and were comparable to VKAs for major bleeding, ischemic stroke, all-cause death, intracranial hemorrhage, and gastrointestinal bleeding.

Oral anticoagulants and concurrent rifampin administration in tuberculosis patients with non-valvular atrial fibrillation

BACKGROUND

Evidence and guidelines for Non-vitamin K antagonist oral anticoagulants (NOACs) use when prescribing concurrent rifampin for tuberculosis treatment in patients with non-valvular atrial fibrillation (NVAF) are limited.

METHODS

Using the Korean National Health Insurance Service database from January 2009 to December 2018, we performed a population-based retrospective cohort study to assess the net adverse clinical events (NACE), a composite of ischemic stroke or systemic embolism and major bleeding, of NOACs compared with warfarin among NVAF patients taking concurrent rifampin administration for tuberculosis treatment. After a propensity matching score (PSM) analysis, Cox proportional hazards regression was performed in matched cohorts to investigate the clinical outcomes.

RESULTS

Of the 735 consecutive patients selected, 465 (63.3%) received warfarin and 270 (36.7%) received NOACs. Among 254 pairs of patients after PSM, the crude incidence rate of NACE was 25.6 in NOAC group and 32.8 per 100 person-years in warfarin group. There was no significant difference between NOAC and warfarin use in NACE (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.48-1.14; P = 0.172). Major bleeding was the main driver of NACE, and NOAC use was associated with a statistically significantly lower risk of major bleeding than that with warfarin use (HR, 0.63; 95% CI, 0.40-1.00; P = 0.0499).

CONCLUSIONS

In our population-based study, there was no statically significant difference in the occurrence of NACE between NOAC and warfarin use. NOAC use may be associated with a lower risk of major bleeding than that with warfarin use.

Drug-drug interaction between dexamethasone and direct-acting oral anticoagulants: a nested case-control study in the National COVID Cohort Collaborative (N3C)

OBJECTIVE

The goal of this work is to evaluate if there is an increase in the risk of thromboembolic events (TEEs) due to concomitant exposure to dexamethasone and apixaban or rivaroxaban. Direct oral anticoagulants (DOACs), as well as corticosteroid dexamethasone, are commonly used to treat individuals hospitalised with COVID-19. Dexamethasone induces cytochrome P450-3A4 enzyme that also metabolises DOACs apixaban and rivaroxaban. This raises a concern about possible interaction between dexamethasone and DOACs that may reduce the efficacy of the DOACs and result in an increased risk of TEE.

DESIGN

We used nested case-control study design.

SETTING

This study was conducted in the National COVID Cohort Collaborative (N3C), the largest electronic health records repository for COVID-19 in the USA.

PARTICIPANTS

Study participants were adults over 18 years who were exposed to a DOAC for 10 or more consecutive days. Exposure to dexamethasone was at least 5 or more consecutive days.

PRIMARY AND SECONDARY OUTCOME MEASURES

Our primary exposure variable was concomitant exposure to dexamethasone for 5 or more days after exposure to either rivaroxaban or apixaban for 5 or more consecutive days. We used McNemar's Χ² test and adjusted logistic regression to evaluate association between concomitant use of dexamethasone with either apixaban or rivaroxaban.

RESULTS

McNemar's Χ² test did not find a discernible association of TEE in patients concomitantly exposed to dexamethasone and a DOAC (χ²=0.5, df=1, p=0.48). In addition, a conditional logistic regression model did not find an increase in the risk of TEE (adjusted OR 1.15, 95% CI 0.32 to 4.18).

CONCLUSION

This nested case-control study did not find evidence of an association between concomitant exposure to dexamethasone and a DOAC with an increase in risk of TEE. Due to small sample size, an association cannot be completely ruled out.

Effect of Polypharmacy on Clinical Outcomes in Elderly Patients With Non-Valvular Atrial Fibrillation - A Sub-Analysis of the ANAFIE Registry

BACKGROUND

This All Nippon AF in the Elderly (ANAFIE) Registry sub-analysis evaluated the impact of polypharmacy on 2-year outcomes in a large, elderly (aged ≥75 years) Japanese population with non-valvular atrial fibrillation (NVAF).

METHODS AND RESULTS

The ANAFIE Registry was a multicenter, prospective, observational study with a 24-month follow-up period. Of 32,275 enrolled NVAF patients, 31,419 were grouped by the number of prescribed concomitant medications (other than oral anticoagulants [OACs]): 0-4 [38.8%], 5-8 [43.3%], and ≥9 [17.9%]). Patients receiving more concomitant medications were older, had poor renal function, and suffered more comorbidities than those receiving fewer concomitant medications. Several patient background factors, including diabetes mellitus, myocardial infarction, and chronic kidney disease, were significantly correlated with an increased number of concomitant medications. With increasing medications, OAC prescription rates decreased, but the warfarin prescription rate increased, and the cumulative incidence rates of stroke/systemic embolic events (SEE), major bleeding, gastrointestinal bleeding, fracture/falls, cardiovascular events, cardiovascular death, and all-cause death significantly increased (each, P<0.05). In multivariate analysis, increasing medications was independently associated with increases in these events, except for stroke/SEE. There were no significant interactions between the number of medications and anticoagulant treatment with direct OAC or warfarin concerning the incidence of these events.

CONCLUSIONS

Polypharmacy was frequent among elderly patients with NVAF who were older with more comorbidities, and was independently associated with a higher incidence of extracranial events.

Recent advances in the management of transient ischemic attacks

Transient ischemic attack (TIA) constitutes an important clinical condition, indicating the presence of considerable risk for a subsequent ischemic stroke. Its prompt diagnosis and management have the potential for reducing the risk of neurologic disability, highlighting the critical need to prioritize the care of patients with TIA. The risk of ischemic stroke following a TIA is directly related to its etiopathogenesis, and recognizable causes are commonly categorized within one of three domains: cerebrovascular pathology, cardiac dysfunction, and hematologic disorders. Therefore, the clinical approach to patients suspected of having suffered a TIA demands a comprehensive evaluation, including testing of possible etiologic conditions in all three of these domains, best carried out in an expedited fashion since the stroke risk is greatest in the hours and days that follow the index event. The present is a review of the existing literature addressing the diagnosis, evaluation, prioritization, and management strategies available to clinicians who provide care to patients with TIA.

Clinically Significant Drug Interactions for Direct Oral Anticoagulants: State of the Art

The article is devoted to modern ideas about the role of drug interactions as a factor affecting the efficacy and safety of the use of direct oral anticoagulants (DOACs) in clinical practice. Data on drug interactions of apixaban, rivaroxaban and dabigatran with the drugs most frequently used in patients with cardiovascular diseases are given. Drug interactions for DOACs, depending on concomitant use of drugs that are inhibitors or inducers of the CYP3A4 enzyme or P-glycoprotein enzymes, are determined by most of the drug interactions of DOACs are considered. The results of studies in which drug interactions of DOACs were assessed by changes in indicators such as the area under the concentration-time curve and the maximum or minimum concentration of drugs in the blood are discussed. The data presented in the article may be useful for accounting for drug interactions in the treatment of patients with DOACs in clinical practice, despite the current lack of reasonable dose adjustment rules depending on the majority of such interactions. The data presented in the article suggest that apixaban has the fewest number of clinically significant interactions among the DOACs available in Russia.

Gastrointestinal bleeding during direct oral anticoagulants therapy in patients with nonvalvular atrial fibrillation and risk of polypharmacy

Although concomitant medications have been raised as a factor affecting hemorrhage during direct oral anticoagulants (DOACs) therapy, details remain unelucidated. This study was conducted to clarify the relationship between concomitant medications with possible pharmacokinetic interactions and number of concomitant medications, and bleeding and embolism in patients with nonvalvular atrial fibrillation on DOACs. The subjects were 1,010 patients prescribed DOACs from a single-center at the Teikyo University Hospital between April 2011 and June 2018. This study was an exploratory analysis and investigated their course between the first prescription and December 2018, including the presence or absence of clinically relevant bleeding, gastrointestinal bleeding, and major cardiovascular and cerebrovascular events. Impacts of medications were evaluated by the general linear model with inverse probability-weighted propensity score. The observation period was 2,272 patient-years. The rate of bleeding was 4.7%/year, gastrointestinal bleeding was 2.8%/year, and major cardiovascular and cerebrovascular events was 2.0%/year. Taking 10 or more oral medications concurrently was a significant risk for gastrointestinal bleeding (hazard ratio, 2.046 [1.188-3.526]; p = 0.010). Nonsteroidal anti-inflammatory drugs (NSAIDs) were the only significant risk for gastrointestinal bleeding. Clinicians should be aware of gastrointestinal bleeding when using DOACs with patients taking more than 10 medications and/or NSAIDs. This article is protected by copyright. All rights reserved.

Ethnic Diversity and Warfarin Pharmacogenomics

Warfarin has remained the most commonly prescribed vitamin K oral anticoagulant worldwide since its approval in 1954. Dosing challenges including having a narrow therapeutic window and a wide interpatient variability in dosing requirements have contributed to making it the most studied drug in terms of genotype-phenotype relationships. However, most of these studies have been conducted in Whites or Asians which means the current pharmacogenomics evidence-base does not reflect ethnic diversity. Due to differences in minor allele frequencies of key genetic variants, studies conducted in Whites/Asians may not be applicable to underrepresented populations such as Blacks, Hispanics/Latinos, American Indians/Alaska Natives and Native Hawaiians/other Pacific Islanders. This may exacerbate health inequalities when Whites/Asians have better anticoagulation profiles due to the existence of validated pharmacogenomic dosing algorithms which fail to perform similarly in the underrepresented populations. To examine the extent to which individual races/ethnicities are represented in the existing body of pharmacogenomic evidence, we review evidence pertaining to published pharmacogenomic dosing algorithms, including clinical utility studies, cost-effectiveness studies and clinical implementation guidelines that have been published in the warfarin field.

Impact of the Genotype and Phenotype of CYP3A and P-gp on the Apixaban and Rivaroxaban Exposure in a Real-World Setting

Apixaban and rivaroxaban are the two most prescribed direct factor Xa inhibitors. With the increased use of DOACs in real-world settings, safety and efficacy concerns have emerged, particularly regarding their concomitant use with other drugs. Increasing evidence highlights drug−drug interactions with CYP3A/P-gp modulators leading to adverse events. However, current recommendations for dose adjustment do not consider CYP3A/P-gp genotype and phenotype. We aimed to determine their impact on apixaban and rivaroxaban blood exposure. Three-hundred hospitalized patients were included. CYP3A and P-gp phenotypic activities were assessed by the metabolic ratio of midazolam and AUC0−6h of fexofenadine, respectively. Relevant CYP3A and ABCB1 genetic polymorphisms were also tested. Capillary blood samples collected at four time-points after apixaban or rivaroxaban administration allowed the calculation of pharmacokinetic parameters. According to the developed multivariable linear regression models, P-gp activity (p < 0.001) and creatinine clearance (CrCl) (p = 0.01) significantly affected apixaban AUC0−6h. P-gp activity (p < 0.001) also significantly impacted rivaroxaban AUC0−6h. The phenotypic switch (from normal to poor metabolizer) of P-gp led to an increase of apixaban and rivaroxaban AUC0−6h by 16% and 25%, respectively, equivalent to a decrease of 38 mL/min in CrCl according to the apixaban model. CYP3A phenotype and tested SNPs of CYP3A/P-gp had no significant impact. In conclusion, P-gp phenotypic activity, rather than known CYP3A/P-gp polymorphisms, could be relevant for dose adjustment.

Evaluating pharmacokinetic drug-drug interactions of direct oral anticoagulants in patients with renal dysfunction

INTRODUCTION

Drug transporters, metabolic enzymes, and renal clearance play significant roles in the pharmacokinetics of direct oral anticoagulants (DOACs). Recommendations for DOAC drug-drug interactions (DDIs) by the product labeling are limited to selected CYP3A4 and P-glycoprotein inhibitors and lack considerations for concomitant renal dysfunction.

AREAS COVERED

This review focuses on: 1) current recommendations for the management of pharmacokinetic DOAC DDIs and the evidence used to support them; 2) alterations in DOAC exposure in the setting of concomitant DDIs and mild, moderate, and severe renal impairment; 3) clinical outcomes associated with this combination; and 4) expert recommendations for the management of pharmacokinetic DOAC DDIs. English-language, full-text articles on apixaban, dabigatran, rivaroxaban, and edoxaban with a publication date up to 30 September 2021 were retrieved from PubMed.

EXPERT OPINION

Given the lack of supporting clinical data, empiric dose adjustments based on pharmacokinetic data alone should be avoided. When a considerable increase in a DOAC exposure is anticipated, it may be advisable to use an alternative DOAC or anticoagulant from a different class. Future research on identification of DOAC therapeutic ranges and target patient populations is needed to inform clinical utility of DOAC level monitoring to guide the management of DDIs.

Polypharmacy Is Associated With Amiodarone-Induced Hypothyroidism

Background: Amiodarone is rich in iodine, so in clinical practice amiodarone-induced hypothyroidism (AIH) is a major side effect. This drug is used in patients with arrhythmias, especially atrial fibrillation, the most common sustained arrhythmia. Polypharmacy, which can result in complex drug-drug interactions, occurs in more than 70% of the patients with atrial fibrillation. Therefore, polypharmacy may be involved in the expression of AIH. In this study, we investigated the association between polypharmacy and AIH. Methods: We conducted a retrospective study using data from January 2006 to May 2020 collected from a large, organized database of prescriptions constructed by the Japan Medical Information Research Institute, Inc. (Tokyo, Japan). To investigate the association between number of prescribed drugs with amiodarone and AIH, we divided patients into two groups: polypharmacy (≥ 5 prescribed drugs) and non-polypharmacy (< 5 prescribed drugs). We then performed a sequence symmetry analysis on the two groups: incident thyroxine after incident amiodarone and incident thyroxine before incident amiodarone. Finally, we conducted a case-control study on two further groups: those prescribed thyroxine after incident amiodarone (AIH group; n=555) and those not prescribed thyroxine after incident amiodarone (non-AIH group; n=6,192). Results: Sequence symmetry analysis revealed a significant association between amiodarone and thyroxine in both the polypharmacy and non-polypharmacy groups. The ranges for the adjusted sequence ratio in the two groups were 12.0-16.7 and 7.3-9.0, respectively. The case-control study showed that ≥5 prescribed drugs at the first prescription of amiodarone were found to significantly increase the odds of AIH (odds ratio: 1.48, 95% confidence interval: 1.18-1.84). Conclusion: Polypharmacy was suggested as an independent risk factor for AIH. Careful assessment of the appropriateness of prescription is warranted.

Prescription patterns of direct oral anticoagulants and concomitant use of interacting medications in the Netherlands

Objectives

To describe the prevalence, temporal and regional trends in prescribing direct oral anticoagulants (DOACs) in conjunction with interacting medications.

Methods

We performed a cross-sectional study of pharmacy dispensing data in the Foundation for Pharmaceutical Statistics (SFK) registry on patients who have had a prescription for a DOAC filled at one of 831 randomly selected pharmacies in the Netherlands between Jan 2014–Jan 2019.

Results

We identified 99,211 patients who had a first DOAC prescription filled. Mean age was 71.6 ± 10.9 years, 58% were male. In 2014, 8,293 patients were treated with DOACs, in 2018, 35,415 were newly started on a DOAC. In 2018, the use of apixaban was most common (52%) in the Eastern region, whereas rivaroxaban was most frequently prescribed (32–48%) in the other regions. At time of first prescription, the vast majority (99.3%) used ≥ 1 concomitant interacting drug, and 3.2% used ≥ 3 interacting medications. Most common were digoxin (37.8%), atorvastatin (31.5%), verapamil (13.7%) and amiodarone (9.7%). While the number of interacting medications remained unchanged over time (median 1, interquartile range 1–1), there was a notable decrease in antiarrhythmic medications and an increase in non-cardiovascular interacting medications (e.g. dexamethasone from 0.9% to 7.1%, antiepileptic drugs from 2.5% to 3.8%, and haloperidol from 0.5% to 2.2% in 2014 and 2018, respectively).

Conclusion

DOAC use has quadrupled in Dutch clinical practice over the 5‑year period from 2014 to 2018. While the number of patients who take interacting medications remained stable, the profile of interacting medications has changed over time from cardiovascular to medications affecting other organ systems.

Supplementary Information

The online version of this article (10.1007/s12471-021-01612-4) contains supplementary material, which is available to authorized users.

Association Between Use of Pharmacokinetic-Interacting Drugs and Effectiveness and Safety of Direct Acting Oral Anticoagulants: Nested Case-Control Study

Concomitant use of direct oral anticoagulants (DOACs) and medications with inhibition/induction effect on P-gp/CYP3A might increase risk of bleeding/treatment failure, respectively. We designed a nested case-control study within a Clalit cohort of patients with atrial fibrillation (AF) and a cohort of patients with venous thromboembolism, new users of a DOAC (January 1, 2010 to August 24, 2020). Propensity scores were constructed from demographic/clinical characteristics, and medications at cohort entry. Each case of: (i) serious bleeding event; (ii) stroke/systemic emboli (SE) in patients with AF; (iii) recurrent thromboembolism in patients with thromboembolism, was matched by age, sex, length of follow-up, year of cohort entry, DOAC type, and DOAC indication, to up to 20 controls. Within 89,284 patients with AF and venous thromboembolism and 126,302 patient-years of follow-up, there were 1,587 serious bleeding events. Risk of serious bleeding increased in association with concurrent prescription of P-gp/CYP3A4 inhibitors. Specifically, higher bleeding risk was associated with dabigatran-verapamil, rivaroxaban-verapamil, and rivaroxaban-amiodarone concurrent prescriptions: adjusted odds ratios (ORs) 2.29 (1.13-4.60), 2.18 (1.07-4.40), and 1.68 (1.14-2.49), respectively. There were 1,116 events of stroke/SE, in 79,302 DOAC-treated patients with AF and 118,124 patient-years of follow-up. Concomitant use of phenytoin, carbamazepine, valproic acid, or levetiracetam was associated with risk for stroke/SE: adjusted OR 2.18 (1.55-3.10). Risk of recurrent venous thromboembolism could not be assessed due to the low number of cases. Concurrent prescriptions of dabigatran or rivaroxaban with verapamil, and of rivaroxaban with amiodarone, are associated with increased risk for serious bleeding. Higher risk for stroke/SE in patients with AF is associated with concurrent prescriptions of DOACs with phenytoin, carbamazepine, valproic acid, or levetiracetam.

Perpetrator Characteristics of Azole Antifungal Drugs on Three Oral Factor Xa Inhibitors Administered as a Microdosed Cocktail

Background

Factor Xa inhibitors (FXaIs) are increasingly used without having sufficient drug–drug interaction data. Using a microdosed cocktail methodology could support filling the knowledge gap quickly.

Methods

In a randomised crossover trial, we investigated the drug–drug interactions between six oral azole antifungals and a microdosed FXaI cocktail containing 25 µg rivaroxaban, 25 µg apixaban, and 50 µg edoxaban. Additionally, different enzyme activities were also monitored using a microdosed cocktail approach. The six different azole antifungals were administered in therapeutic doses over a 24 h period, while the microdosed cocktails were administered 1 h after administration of the azole antifungals.

Results

Ketoconazole and posaconazole were the strongest perpetrators, showing similar increases as apixaban (area under the concentration–time curve ratio [AUCR] 1.64 and 1.62, respectively) and edoxaban (AUCR 2.08 and 2.1, respectively), whereas ketoconazole increased rivaroxaban 2.32-fold but only increased posaconazole 1.37-fold. All other azole antifungals showed less perpetrator effects on the FXaIs. Cytochrome P450 (CYP) 3A inhibition was confirmed using microdosed midazolam, with ketoconazole also the most potent perpetrator (8.42-fold).

Conclusion

Drug–drug interactions for three victim drugs of the same drug class (FXaIs) with different clearance mechanisms can be studied using a microdosed cocktail approach. Using members of the azole antifungal drug class as perpetrators, multiple interactions can be studied in one trial, and a more detailed insight into the underlying interaction mechanisms is possible.

Clinical Trial Registration

EudraCT number: 2017-004453-16.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-021-01051-9.

Comparative Effectiveness and Safety of Rivaroxaban and Warfarin Among Nonvalvular Atrial Fibrillation (NVAF) Patients with Obesity and Polypharmacy in the United States (US)

Introduction

Current evidence indicates that rivaroxaban may be a safe and effective alternative to warfarin among patients with nonvalvular atrial fibrillation (NVAF) and obesity. However, evidence regarding the impact of polypharmacy is limited in this population. The present study evaluated the effectiveness and safety of rivaroxaban versus warfarin among NVAF patients with obesity and polypharmacy in the US.

Methods

De-identified health insurance claims data from the IQVIA PharMetrics^® Plus data (01/2010–09/2019) were used to identify NVAF patients with obesity (BMI ≥ 30 kg/m²) and polypharmacy (≥ 5 medications) initiated on rivaroxaban or warfarin. Inverse probability of treatment weighting (IPTW) was used to adjust for imbalances between groups. Study outcomes were evaluated up to 36 months post-treatment initiation and included the composite of stroke or systemic embolism (stroke/SE) and major bleeding. Subgroup analyses were conducted stratified by polypharmacy category (5–9 or ≥ 10 medications). Outcomes were assessed using Cox proportional hazards regression models with hazard ratios (HR) and 95% confidence intervals (CIs).

Results

A total of 7000 and 3920 NVAF patients with obesity and polypharmacy were initiated on rivaroxaban and warfarin, respectively. At 36 months of follow-up, rivaroxaban was associated with a 29% lower risk of stroke/SE relative to warfarin (HR 0.71, 95% CI 0.57, 0.90). Major bleeding risk was not significantly different among rivaroxaban- compared to warfarin-treated patients (HR 0.85, 95% CI 0.70, 1.03). Subgroup analyses yielded results that were largely consistent with the overall polypharmacy analysis.

Conclusions

These results suggest that rivaroxaban is an effective and safe treatment option among NVAF patients with obesity and polypharmacy in a commercially-insured US population.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12325-021-01746-2.

Antithrombotic therapy in the elderly and senile age: the consensus opinion of experts of the Russian Association of Gerontologists and Geriatricians and the National Society of Preventive Cardiology

В данном документе обсуждаются особенности АТТ у лиц пожилого и старческого возраста в различных клинических ситуациях.

Comparison of potential pharmacokinetic drug interactions in patients with atrial fibrillation and changing from warfarin to non-vitamin K oral anticoagulant therapy

There are now anticoagulant choices with proposed advantages of non-vitamin K oral anticoagulants (NOACs) over warfarin being less routine monitoring and less drug interactions. Interacting medication can impact the efficacy and safety of anticoagulant therapy with management remaining clinically challenging. There have been limited studies comparing the potential for pharmacokinetic (PK) drug interactions between different anticoagulants. Therefore, the aim of this study was to compare potential PK interactions in patients with atrial fibrillation (AF) changing from warfarin to NOAC therapy. A retrospective analysis was conducted of patients with AF enrolled in a dedicated warfarin program but exiting this program to commence a NOAC. Patient data was collected, and concurrent medications were utilised to identify potential PK drug interactions with both warfarin and the chosen NOAC therapy. Patients were grouped according to the number of medications with potential PK interactions and comparisons made between groups. Of the 712 eligible patients who ceased warfarin to commence a NOAC, most commenced either apixaban (45.9%) or rivaroxaban (41.9%). When comparing warfarin to NOACs, there were significant differences in the proportion of patients taking no medication with potential PK drug interactions (46.9% vs 62.8%, p < 0.0001), and taking one (35.2% vs 28.5%, p = 0.0067) and two (14.5% vs 7.3%, p < 0.0001) potentially PK interacting medications. This study found when patients with AF were switched from warfarin to a NOAC, the potential for PK drug interactions significantly reduced but remained around 40%. Identifying and managing potential PK drug interactions with NOACs remains a priority to optimise clinical benefit of these anticoagulants.

Frequency, Trend, Predictors, and Impact of Gastrointestinal Bleeding in Atrial Fibrillation Hospitalizations

Anticoagulation alone or in combination with other treatment strategies are implemented to reduce the risk of stroke in patients with atrial fibrillation (AF). Gastrointestinal bleeding (GIB) is a common complication of oral anticoagulation with a prevalence of 1% to 3% in patients on long term oral anticoagulation. We analyzed the national inpatient sample database from the year 2005 to 2015 to report evidence on the frequency, trends, predictors, clinical outcomes, and economic burden of GIB among AF hospitalizations. A total of 34,260,000 AF hospitalizations without GIB and 1,846,259 hospitalizations with GIB (5.39%) were included. The trend of AF hospitalizations with GIB per 100 AF hospitalizations remained stable from the year 2005 to 2015 (p value = 0.0562). AF hospitalizations with GIB had a higher frequency of congestive heart failure, long term kidney disease, long term liver disease, anemia, and alcohol abuse compared with AF hospitalizations without GIB. AF hospitalizations with GIB had a higher odds of in-hospital mortality (Odds ratio (OR) 1.47; 95% Confidence interval (CI): 1.46 to 1.48, p-value <0.0001), mechanical ventilation (OR 1.69; 95% CI: 1.68 to 1.70, p-value <0.0001), and blood transfusion (OR 7.2; 95% CI: 7.17 to 7.22, P-value <0.0001) compared with AF hospitalizations without GIB. AF hospitalizations with GIB had a lower odds of stroke (OR 0.51; 95% CI: 0.51 to 0.52, p-value <0.0001) compared with AF hospitalizations without GIB. Further, AF hospitalizations with GIB had a higher median length of stay and cost of hospitalization compared with AF hospitalizations without GIB. In conclusion, the frequency of GIB is 5.4% in AF hospitalizations and the frequency of GIB remained stable in the last decade as shown in this analysis. When GIB occurs, it is associated with higher resource utilization. This study addresses a significant knowledge gap highlighting national temporal trends of GIB and associated outcomes in AF hospitalizations.

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.

Adverse drug reactions with oral anticoagulants: data from sicilian spontaneous reporting system database

OBJECTIVE

Direct oral anticoagulants (DOACs) were developed to avoid the limitations of vitamin K antagonists (VKAs). DOACs are associated with a greater incidence of gastrointestinal bleeding and a smaller number of intracranial haemorrhages than VKAs. Therefore, it is important to deepen our knowledge of their safety profiles. The aim of this study was thus to analyse adverse drug reaction (ADR) reports on DOACs and VKAs using the Sicilian Spontaneous Reporting System (SRS) database.

METHODS

All ADR reports with DOACs and VKAs as suspected drugs that were entered into the Sicilian SRS database during the period 2001-2019 were selected. In detail, all reports with the following single active substances were included: dabigatran etexilate, rivaroxaban, apixaban and edoxaban; acenocoumarol and warfarin were included as a comparator group. Descriptive statistical methodology was used to evaluate characteristics of the reported cases with a case-by-case assessment.

RESULTS AND DISCUSSION

Out of 521 reports related to anticoagulants, 444 (85.2%) and 77 (14.8%) involved DOACs and VKAs, respectively. DOAC-related reports were mainly of gastrointestinal disorders. In contrast, VKAs were mostly associated with blood and lymphatic system disorders, injury, investigations and vascular disorders. Many more cases of ADRs in the form of gastrointestinal disorders concerned dabigatran etexilate (n = 179, 73.7%) than the other DOACs, while ADRs in the form of blood disorders were mainly associated with acenocoumarol (n = 27, 57.4%). The most commonly reported Preferred Terms for DOACs were dyspepsia (n = 89, 17.1%), upper abdominal pain (n = 41, 9.2%) and pruritus (n = 26, 5.8%), whereas for VKAs, they were anaemia (n = 21, 27.3%) and hypocoagulable state (n = 18, 3.5%). Potentially interacting concomitant medications particularly included antithrombotic agents (n = 19, 4.3%) for DOACs and proton-pump inhibitors (PPIs) (n = 37, 48.1%) and antithrombotic agents (n = 13, 16.9%) for VKAs.

CONCLUSION

The ADRs most commonly associated with DOACs, especially dabigatran, were gastrointestinal disorders, particularly gastrointestinal bleeding. Our study also highlights the potential role of drug-drug interactions in the ADRs. The cases of gastrointestinal bleeding highlight the need for careful prescribing of DOACs and use of potentially interacting concomitant drugs.

The Oral Anticoagulants Administration in Elderly Patients with Geriatric Syndromes: What's New?

The administration of oral anticoagulants in elderly patients with geriatric syndromes such as senile asthenia syndrome, falls and high risk of falls, dementia, polymorbidity, polypharmacy are discussed in the article. The evidence base for the anticoagulants taking in patients with atrial fibrillation aged ≥75, ≥80, ≥85 and ≥90 years, in patients with atrial fibrillation and various geriatric syndromes, as well as in elderly patients with venous thromboembolic complications and frailty syndrome is presented. Most studies indicate significant advantages of direct oral anticoagulants (dabigatran, rivaroxaban, apixaban, and edoxaban) over the vitamin K antagonist warfarin in elderly patients with geriatric syndromes. An updated version of the FORTA consensus document, which aims to optimize the prescription of medicines for the elderly, is also presented. Apixaban has a FORTA-A safety class and is the safest oral anticoagulant in elderly patients.

Drug-Drug Interactions between Direct Oral Anticoagulants and Hepatitis C Direct-Acting Antiviral Agents: Looking for Evidence Through a Systematic Review

Background

Direct oral anticoagulants (DOACs), as substrates of cytochrome P450 (CYP) 3A4 and/or P-glycoprotein, are susceptible to drug–drug interactions (DDIs). Hepatitis C direct-acting antiviral agents (DAAs), via P-glycoprotein or CYP3A4 inhibition, may increase DOAC exposure with relevant bleeding risk. We performed a systematic review on DDIs between DOACs and DAAs.

Methods

Two reviewers independently identified studies through electronic databases, until 7 July 2020, supplementing the search by reviewing conference abstracts and the ClinicalTrials.gov website.

Results

Of 1386 identified references, four articles were finally included after applying the exclusion criteria. Three phase I clinical studies in healthy volunteers assessed interactions between dabigatran and glecaprevir/pibrentasvir, odalasvir/simeprevir, or sofosbuvir/velpatasvir/voxilaprevir, showing an increase in the dabigatran area under the concentration–time curve (AUC) by 138%, 103%, and 161%, respectively.

Conclusions

DOACs and DAAs are under-investigated for DDI risk. Real-world studies are needed to assess the clinical relevance of the pharmacokinetic interactions with dabigatran and describe the actual spectrum of possible DDIs between DAAs and other DOACs.

Effects of Carbamazepine and Phenytoin on Pharmacokinetics and Pharmacodynamics of Rivaroxaban

Rivaroxaban (RIV) is commonly prescribed with carbamazepine or phenytoin (CBZ/PHT) in post-stroke seizure or post-stroke epilepsy patients. Although adverse events have been reported in several previous studies when they are coadministered, there are no studies of the interactions between these drugs. Therefore, our study was conducted to solve this lack of information. The potential effects of CBZ/PHT were investigated by comparing the pharmacokinetic (PK) and pharmacodynamic (PD) parameters of RIV between the control group (RIV alone) and the test groups (RIV administered with CBZ/PHT) in rats using the noncompartmental analysis (NCA) and the compartmental model approach. The NCA results indicate that AUC_t of RIV decreased by 57.9% or 89.7% and C_max of RIV decreased by 43.3% or 70.0% after administration of CBZ/PHT, respectively. In addition, both CBZ and PHT generally reduced the effects of RIV on the prothrombin times of the blood samples. PK profiles of RIV were most properly described by a two-compartment disposition model with a mixed first- and zero-order absorption kinetics and a first-order elimination kinetics. The compartmental model approach showed that a 211% or 1030% increase in CL/F of RIV and a 33.9% or 43.4% increase in D2 of RIV were observed in the test groups by the effects of CBZ/PHT, respectively. In conclusion, CBZ and PHT significantly reduced RIV exposure and therefore reduced the therapeutic effects of RIV. Consequently, this might result in adverse events due to insufficient RIV concentration to attain its therapeutic effects. Further studies are needed to validate this finding.

Bleeding and thromboembolism due to drug-drug interactions with non-vitamin K antagonist oral anticoagulants-a Swedish, register-based cohort study in atrial fibrillation outpatients

PURPOSE

To study the association between interacting drugs and bleeding or thromboembolism in atrial fibrillation outpatients treated with non-vitamin K antagonist oral anticoagulants (NOACs).

METHODS

Population-based cohort study of outpatients treated with NOACs in Sweden from 2008 to 2017. Patients with atrial fibrillation and newly initiated NOAC treatment were identified in the Prescribed Drug Register. Comorbidities and outcome data were retrieved from the Patient Register and the Cause of Death Register. Cox-regression analyses were performed to evaluate the primary endpoints any severe bleed and ischemic stroke/transient ischemic attack/stroke unspecified during the first six months of treatment. Secondary endpoints were gastrointestinal bleeding, intracranial bleeding, ischemic stroke, and venous thromboembolism.

RESULTS

Increased risk of any severe bleed was found when NOAC treatment, and drugs with pharmacodynamic effect on bleeding were combined, compared to NOAC only. An increased risk with these combinations was evident for apixaban (hazard ratio (HR) 1.47; 95% CI 1.33-1.63), rivaroxaban (HR 1.7; 95% CI 1.49-1.92), and dabigatran (HR 1.26; 95% CI 1.05-1.52). For apixaban, there was an increased risk of any severe bleed when combined with CYP3A4 and/or P-glycoprotein (P-gp) inhibitors (HR 1.23; 95% CI 1.01-1.5). The use of inducers of CYP3A4 and/or P-gp was low in this cohort, and effects on ischemic stroke/TIA/stroke unspecified could not be established.

CONCLUSION

Increased risk of bleeding was seen for pharmacodynamic and pharmacokinetic interactions with NOACs. Prescribers need to be vigilant of the effect of interacting drugs on the risk profile of patients treated with NOACs.

Effectiveness and Safety of Oral Anticoagulants in Older Patients With Atrial Fibrillation: A Systematic Review and Meta-Analysis

Background and Objective

Atrial fibrillation (AF), the most common cardiac arrhythmia, typically increases with age. Oral anticoagulants (OACs) are the cornerstone of treatment to reduce the associated risk for systemic thromboembolism. Four large randomized controlled trials (RCTs) have shown that non-vitamin K antagonist oral anticoagulants (NOACs) are non-inferior to vitamin K antagonists (VKAs) in preventing stroke and systemic embolism, as well as regarding their risk for major bleeding. However, as vulnerable geriatric patients with AF were largely underrepresented in these trials, physicians are faced with the challenge of choosing the right anticoagulant for geriatric patients in real-life clinical practice. In this vulnerable patient group, NOACs tend to be underused or underdosed due to concerns of excessive fall-related intracranial bleeding, cognitive impairment, multiple drug-drug interactions, low body weight or impaired renal function. As life expectancy continues to rise worldwide, the number of geriatric patients substantially increases. Therefore, there is an urgent need for a critical appraisal of the added value of NOACs in geriatric patients with AF at high thromboembolic and bleeding risk.

Methods and Results

This systematic review provides an overview of the literature on the impact of increased age (≥75 years), multimorbidity, polypharmacy, increased falling risk, frailty and dementia on the effectiveness and safety of NOACs as compared to VKAs, after searching the Medline database. Moreover, a meta-analysis on the impact of increased age ≥75 years old was performed after pooling results from 6 post hoc analyses of RCTs and 6 longitudinal observational cohort studies, highlighting the superior effectiveness (hazard ratio (HR) 0.83, 95% confidence interval (CI) [0.74–0.94] for stroke/SE; HR 0.77, 95%CI [0.65–0.92] for mortality) and non-inferior safety (HR 0.93, 95%CI [0.86–1.01] for major bleeding; HR 0.58, 95%CI [0.50–0.67] for intracranial bleeding; HR 1.17, 95%CI [0.99–1.38] for gastrointestinal bleeding) of NOACs versus VKAs in older AF patients.

Conclusion

Across geriatric subgroups, apixaban was consistently associated with the most favourable benefit-risk profile and should therefore be preferred in geriatric patients with AF. However, research gaps on the impact of increased falling risk, frailty and baseline dementia were identified, requiring careful consideration while awaiting more results.

Direct oral anticoagulants for patients aged over 80 years in nonvalvular atrial fibrillation: the impact of frailty

AIMS

In patients aged at least 80 years, atrial fibrillation is responsible for significant morbidity and mortality, with a high incidence of stroke. Four new direct oral anticoagulants (DOACs) have been introduced in Italy for the prevention of thromboembolism. Their safety and efficacy in the elderly have already been confirmed. Frailty is frequently associated with aging, but only a few studies have paid attention to interactions between frailty and anticoagulation therapy.

METHODS

We retrospectively evaluated the effectiveness and safety of DOACs in a population aged at least 80 years. Frailty was appraised using an adaptation of the Reported Edmonton Frail Scale, considering a value at least 8 (on a scale from 0 to 18).

RESULTS

The majority (644/731) of patients remained on DOACs for more than 1 year. A total of 19 patients experienced a thrombotic event while on anticoagulation (1.11 events per 100 person-years) and 26 patients a major bleeding episode (1.52 events per 100 person-years). The probability of interrupting therapy increased significantly with frailty [hazard ratio 2.91 with confidence interval (CI) 2.15-3.92 at univariate analysis, hazard ratio 2.80 with CI 2.03-3.86 at multivariate]; frailty showed a significant impact also on major bleeding (hazard ratio 3.28 with CI 1.45-7.37 at univariate analysis, hazard ratio 3.56 with CI 1.58-8.01 at multivariate).

CONCLUSION

Our study highlights how DOACs are a safe and effective option for anticoagulation, even in frail elderly people; the introduction of these drugs is leading to an increased use of anticoagulation therapy in this population. Prospective trials will be needed to reinforce these results and to consider new variables in the thrombotic and hemorrhagic risk scores underlying the prescription of DOACs.

Drug-Drug Interactions with Direct Oral Anticoagulants

A large body of evidence suggests that not only direct anticoagulant effects but also major bleeding events and stroke prevention depend on plasma concentrations of direct oral anticoagulants (DOACs). Concomitant drugs that cause drug–drug interactions (DDIs) alter DOAC exposure by increasing or decreasing DOAC bioavailability and/or clearance; hence, they might affect the efficacy and safety of DOAC therapy. Patients with renal impairment already receive smaller DOAC maintenance doses because avoidance of elevated DOAC exposure might prevent serious bleeding events. For other causes of increased exposure such as DDIs, management is often less well-defined. Considering that DOAC patients are often older and have multiple co-morbidities, polypharmacy is highly prevalent. However, the effect of multiple drugs on DOAC exposure, and especially the impact of DDIs when concurring with drug–disease interactions as observed in renal impairment, has not been thoroughly elucidated. In order to provide effective and safe anticoagulation with DOACs, understanding the mechanisms and magnitude of DDIs appears relevant. Instead of avoiding drug combinations with DOACs, more DDI trials should be conducted and new strategies such as dose adjustments based on therapeutic drug monitoring should be investigated. However, dose adjustments based on concentration measurements cannot currently be recommended because evidence-based data are missing.