Potential drug-drug interactions with direct oral anticoagulants in elderly hospitalized patients

Interactions between antiepileptic drugs and direct oral anticoagulants for primary and secondary stroke prevention

INTRODUCTION

Direct oral anticoagulants (DOAC) are the guideline-recommended therapy for prevention of stroke in atrial fibrillation (AF) and venous thromboembolism. Since approximately 10% of patients using antiepileptic drugs (AED) also receive DOAC, aim of this review is to summarize data about drug-drug interactions (DDI) of DOAC with AED by using data from PubMed until December 2023.

AREAS COVERED

Of 49 AED, only 16 have been investigated regarding DDI with DOAC by case reports or observational studies. No increased risk for stroke was reported only for topiramate, zonisamide, pregabalin, and gabapentin, whereas for the remaining 12 AED conflicting results regarding the risk for stroke and bleeding were found. Further 16 AED have the potential for pharmacodynamic or pharmacokinetic DDI, but no data regarding DOAC are available. For the remaining 17 AED it is unknown if they have DDI with DOAC.

EXPERT OPINION

Knowledge about pharmacokinetic and pharmacodynamic DDI of AED and DOAC is limited and frequently restricted to in vitro and in vivo findings. Since no data about DDI with DOAC are available for 67% of AED and an increasing number of patients have a combined medication of DOAC and AED, there is an urgent need for research on this topic.

Management of direct oral anticoagulant drug interactions in hospitalized patients

Moderate-strong CYP3A4 or Pgp inhibitors and inducers alter direct oral anticoagulant (DOAC) pharmacokinetics. Whether the presence of a DOAC drug-drug interaction (DDI) prompts in- hospital changes in management remains unknown. We identified all hospitalized patients at our institution who were admitted with a clinically relevant DOAC DDI from 01/2021 to 06/2021. Clinically relevant DOAC DDIs were defined as those listed in the prescribing information or FDA CYP3A4/Pgp inhibitors clinical indexes. We assessed the prevalence of DOAC DDIs and categorized their management as: drug stopped, drug held, or drug continued. For drugs that were continued we assessed whether the dose of the DOAC or interacting drug was increased, decreased or unchanged during the admission. We ascertained the number of DOAC DDIs that prompted an automated prescribing alert in our electronic health record (EHR). Finally, we conducted a logistic regression model to compare users of DOACs with DDI who had their regimen adjusted versus those without adjustments, focusing on outcomes of rehospitalization and death, adjusting for age and gender. Among 3,725 hospitalizations with a DOAC admission order, 197 (5%) had a clinically relevant DOAC DDI. The DOAC and the interacting drug were continued at discharge for 124 (63%) hospitalizations. The most frequent adjustments were stopping the interacting drug (73%) and stopping the DOAC (15%). Only 7 (4%) of DOAC DDIs prompted an EHR alert. The adjusted odds ratios for rehospitalizations and death, respectively, among patients whose regimens were adjusted compared to those whose were not, were 1.29 (95% CI, 0.67 to 2.48; P = 0.44) and 1.88 (95% CI, 0.91 to 3.89; P = 0.09). Clinically relevant DDIs with DOACs occur infrequently among hospitalized patients and usually are managed without stopping the DOAC. The clinical impact of such DDIs and subsequent adjustments on thrombotic and hemorrhagic outcomes requires further investigation.

Pharmacogenomics - a minor rather than major force in clinical medicine

INTRODUCTION

Pharmacogenomics (PGx) is touted as essential for the future of precision medicine. But the opportunity cost of PGx from the prescribers' perspective is rarely considered. The aim of this article is to critique PGx-guided prescribing using clinical pharmacology principles so that important cases for PGx testing are not missed by doctors responsible for therapeutic decision making.

AREAS COVERED

Three categories of PGx and their limitations are outlined - exposure PGx, response PGx, and immune-mediated safety PGx. Clinical pharmacology reasons are given for the narrow scope of PGx-guided prescribing apart from a few medical specialties. Clinical problems for doctors that may arise from PGx are then explained, including mismatch between patients' expectations of PGx testing and the benefits or answers it provides.

EXPERT OPINION

Contrary to popular opinion, PGx is unlikely to become the cornerstone of precision medicine. Sound clinical pharmacology reasons explain why PGx-guided prescribing is unnecessary for most drugs. Pharmacogenomics is important for niche areas of prescribing but has limited clinical utility more broadly. The opportunity cost of PGx-guided prescribing is currently too great for most doctors.

Managing the Drug-Drug Interaction With Apixaban and Primidone: A Case Report

The management of the drug-drug interaction (DDI) between primidone, a moderate to strong cytochrome P-450 (CYP) 3A4 inducer, and apixaban, a direct oral anticoagulant (DOAC) and CYP3A4 substrate is complex and limited evidence exists to guide management. This case report describes a 65-year-old male, receiving primidone for essential tremor who developed an acute venous thromboembolism (VTE) requiring oral anticoagulation. DOACs are preferred over vitamin K antagonists for acute VTE treatment. Based on patient-specific variables, provider preference, and the avoidance of other DDIs, apixaban was selected. Apixaban's package insert recommends avoiding use with concomitant strong P-gp and CYP3A4 inducers due to the decreased exposure to apixaban; however, no recommendations are available for drugs that are moderate to strong CYP3A4 inducers and lack P-gp effects. Given that phenobarbital is an active metabolite of primidone, extrapolation of evidence from such literature is theoretical but provides insight into the management of this multi-faceted DDI. In the absence of the ability to monitor plasma apixaban levels, a management strategy of avoidance with a washout period of primidone based on pharmacokinetic parameters was used in this case. Additional evidence is needed to clearly understand the degree of impact and clinical significance of the DDI between apixaban and primidone.

[Prophylaxis and management of cancer-associated thrombosis: Practical issues about anticoagulant use]

Cancer-associated thrombosis (CAT) is a common complication resulting from various vascular mechanisms related to cancer, antitumoral therapy and patient status, and is associated with a poor prognosis. Anticoagulants recommended for CAT treatment or prevention mainly include low molecular weight heparin (LMWH) and direct oral anticoagulants (DOACs). Regarding thromboprophylaxis, a situation for which LMWH is a preferred option due to a lower risk of hemorrhage especially in patients with unresected gastro-intestinal and genito-urinary malignancies, the identification of patients at risk is a major issue. For patients with established CAT, the main issue is the choice of the most appropriate anticoagulant therapy. Because of the convenience of oral formulation, DOACs are an attractive option, and their efficacy has been shown in randomized trials. However, such studies are limited by selection biases, which make the analyzed population not representative of the real-life setting, as for instance cancers associated with a high risk of hemorrhage, or antitumoral therapies (e.g., tyrosine kinase inhibitors) known to interact with DOACs and then modifying their bioavailability. Caution associated with DOAC use is highlighted by most updated guidelines that recommend a case-by-case-based approach. The aim of the present paper is to help the oncologists make the most appropriate decision regarding the choice of anticoagulant therapy in a context of thromboprophylaxis or established CAT management in a patient with a solid tumor. The main issues are addressed through key practical questions, the answers of which are based on the current guidelines and additional published data or expert opinions.

Impact of drug interactions with direct oral anticoagulants on mortality in elderly with atrial fibrillation during the COVID-19 pandemic

Objective

To evaluate the effect of drug interactions with chronic direct oral anticoagulants (DOAC) on mortality in older atrial fibrillation (AF) patients during the Coronavirus disease 2019(COVID-19) pandemic.

Methods

We followed a total of 601 elderly patients (65 years of age) from the NOEL-Drug Registry cohort who were referred to a tertiary outpatient clinic between 9 March 2020 and 1 March 2021. We recorded clinical characteristics and medications for the last 3 months. In addition, all drug interactions were identified using Lexicomp®. Finally, we recorded retrospectively all death events, COVID-19 diagnosis, and relevant deaths from the database at the end of the study. According to logistic regression, we performed propensity score (PS) matching to reduce potential bias. Factors associated with total mortality in the 12 months were analyzed using multivariable Cox proportion hazard analysis.

Results

The mean age [standard deviation (SD)] was 74.5 (±6.9), and the male/female ratio was 337/264. The prevalence of total mortality was 16.9% (n = 102). A total of 4472 drugs were analyzed for DOAC interaction. 81.8% of older AF patients were not at risk in terms of potential interaction. In the Cox proportional hazard model after PS-matching, previous DOAC use with class X interaction was associated with significantly higher mortality risk (adjusted hazard ratio: 2.745, 95% confidence interval: 1.465-5.172, p = 0.004).

Conclusions

Our study showed that while most co-medications do not have significant interactions with DOACs, few serious drug interactions contribute to mortality in elderly patients with AF during the pandemic.

Impact of drug interactions with direct oral anticoagulants on mortality in elderly with atrial fibrillation during the COVID-19 pandemic

OBJECTIVE

To evaluate the effect of drug interactions with chronic direct oral anticoagulants (DOAC) on mortality in older atrial fibrillation (AF) patients during the Coronavirus disease 2019(COVID-19) pandemic.

METHODS

We followed a total of 601 elderly patients (65 years of age) from the NOEL-Drug Registry cohort who were referred to a tertiary outpatient clinic between 9 March 2020 and 1 March 2021. We recorded clinical characteristics and medications for the last 3 months. In addition, all drug interactions were identified using Lexicomp®. Finally, we recorded retrospectively all death events, COVID-19 diagnosis, and relevant deaths from the database at the end of the study. According to logistic regression, we performed propensity score (PS) matching to reduce potential bias. Factors associated with total mortality in the 12 months were analyzed using multivariable Cox proportion hazard analysis.

RESULTS

The mean age [standard deviation (SD)] was 74.5 (±6.9), and the male/female ratio was 337/264. The prevalence of total mortality was 16.9% (n=102). A total of 4472 drugs were analyzed for DOAC interaction. 81.8% of older AF patients were not at risk in terms of potential interaction. In the Cox proportional hazard model after PS-matching, previous DOAC use with class X interaction was associated with significantly higher mortality risk (adjusted hazard ratio: 2.745, 95% confidence interval: 1.465-5.172, p=0.004).

CONCLUSIONS

Our study showed that while most co-medications do not have significant interactions with DOACs, few serious drug interactions contribute to mortality in elderly patients with AF during the pandemic.

Risk of Bleeding Among Individuals on Direct-Acting Oral Anticoagulants: An Academic Medical Center Cohort Study

ABSTRACT

Previous research has identified risk factors that may affect the risk of bleeding when individuals are exposed to oral anticoagulants. It is unclear if the risk continues to exist with the direct oral anticoagulants (DOACs). The purpose of this study was to assess the risk of bleeding in patients on DOACs (apixaban, rivaroxaban, dabigatran, edoxaban, and betrixaban) based on known risk factors including demographics, medical conditions, and concomitant medications. This study was a retrospective analysis using electronic health record data from the University of Utah Hospital (Division of Cardiovascular Medicine) of individuals receiving a DOAC from 2015 to 2020. The primary outcome of interest was bleeding events [gastrointestinal (GI) bleeding, other anatomical site bleeding (excluding GI), and any bleeding] recorded in the electronic health record that codes using International Classification of Diseases 9th and 10th codes. Known risk factors were used to predict bleeding using multivariate logistic regression. A total of 5492 patients received a DOAC during the study period. Less than half the study population were female (2287, 41.6%). During the follow-up, there were 988 patients (18.0%) experiencing a bleeding event. Of them, 351 patients (35.5%) had a GI bleeding event. Significant risk factors of GI bleeding included clopidogrel [odds ratio (OR) 1.71; 95% confidence interval (95% CI), 1.16-2.52] and previous GI bleeding episodes (OR 7.73; 95% CI, 5.36-11.16). Exposure to corticosteroids (OR 1.50; 95% CI, 1.20-1.87) and previous GI bleeding (OR 1.61; 95% CI, 1.10-2.35) were associated with an increase in bleeding at other anatomical sites (not GI included).

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.

Morbidly Obese Patients Undergoing Primary Total Joint Arthroplasty May Experience Higher Rates of Venous Thromboembolism When Prescribed Direct Oral Anticoagulants vs Aspirin

BACKGROUND

Morbidly obese (body mass index [BMI] >40 kg/m²) patients undergoing total joint arthroplasty (TJA) are at high risk for postoperative venous thromboembolism (VTE); however, there is debate surrounding the optimal pharmacologic agent for prevention of VTE after TJA in this patient subset. Current guidelines recommend against direct-acting oral anticoagulants (DOACs) in patients of BMI >40 kg/m² due to low quality evidence justifying their use. We evaluated whether patients of BMI >40 kg/m² undergoing primary unilateral TJA would have increased risk of postoperative VTE if prescribed DOACs compared to non-DOAC agents such as aspirin.

METHODS

This retrospective study analyzed 897 patients of BMI >40 kg/m² undergoing primary unilateral TJA. Demographic and comorbidity-related variables were collected. The association between postoperative VTE and prophylactic pharmacologic agent prescribed was evaluated by multivariate logistic regression.

RESULTS

After controlling for comorbidities, we found that the sole use of DOACs, specifically apixaban, for VTE prophylaxis was associated with an increased risk of developing VTE compared to prophylaxis with aspirin alone in patients of BMI >40 kg/m² (odds ratio 2.962, P = .016). Regardless of VTE prophylactic agent, patients with BMI >40 kg/m² undergoing TKA had at least 4.5-fold increased odds of developing VTE compared to patients undergoing THA (OR 4.830, P = .019).

CONCLUSION

In our retrospective study of a large sample size of patients with BMI >40 kg/m², we found that the use of DOACs, specifically apixaban, for VTE prophylaxis following TJA was associated with increased odds of a VTE complication compared to the use of aspirin alone.

Direct oral anticoagulants versus warfarin for secondary prevention of cerebral infarction and bleeding in older adults with atrial fibrillation

BACKGROUND

Direct oral anticoagulants (DOACs) have been used for both primary and secondary prevention of cerebral infarction in older patients with atrial fibrillation (AF). However, whether DOACs are more effective and safer than warfarin for secondary prevention of cerebral infarction in older patients with AF remains unclear.

METHODS

Using the Japanese Diagnosis Procedure Combination database, we identified patients with AF who were hospitalized for cerebral infarction from January 1, 2015 to March 31, 2019 and were aged ≥75 years at admission. We performed propensity score-stabilized inverse probability of treatment weighting analyses to balance measured confounders between patients with AF receiving DOACs and those receiving warfarin after discharge. The primary outcomes were 365-day readmission for (a) benefit: cerebral infarction or (b) harm: bleeding events after discharge. The secondary outcomes were 365-day readmission for intracranial bleeding or gastrointestinal bleeding after discharge as well as all-cause death during readmission. Using a Fine-Gray model, we compared the subdistribution hazard ratios (SHRs) of readmission between the DOAC group and warfarin group.

RESULTS

We identified 101,389 eligible patients, including 80,726 patients receiving DOACs and 20,663 patients receiving warfarin. After the propensity score-stabilized inverse probability of treatment weighting, the adjusted SHRs of readmission (95% confidence interval [CI]) for cerebral infarction, bleeding events, and intracranial bleeding in the DOAC group as compared with the warfarin group were 0.76 (0.71-0.81), 0.78 (0.68-0.90), and 0.69 (0.57-0.82), respectively. There was no significant difference in readmission for gastrointestinal bleeding (SHR, 1.01; 95% CI, 0.72-1.41) between the DOAC and warfarin groups.

CONCLUSION

In this retrospective nationwide study, DOACs were more effective and safer than warfarin for preventing reinfarction and bleeding events in patients with AF aged ≥75 years who have a history of cerebral infarction.

Acute elevation of liver function test values following concomitant administration of dabigatran and primidone

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

We report a unique case of transiently elevated liver function test (LFT) values associated with concurrent use of dabigatran and primidone, which has not previously been described in the scientific literature.

SUMMARY

Management of drug-drug interactions requires a fundamental understanding of pharmacodynamic and pharmacokinetic parameters. Despite the use of available best predictive models, idiosyncratic drug reactions may still occur when a newly approved medication begins to be used in the general population. We report a case of a possible interaction (Naranjo adverse drug reaction probability score of 3, Roussel Uclaf causality assessment method score of 3) between dabigatran and primidone in a 70-year-old Caucasian male resulting in a transient elevation of LFT values. The patient was transitioned from warfarin to dabigatran in the setting of persistently subtherapeutic international normalized ratio values. During a routine outpatient follow-up appointment approximately 1 month after dabigatran initiation, the patient was discovered to have LFT values greater than 5 times the upper limit of normal. Dabigatran was thus discontinued; the patient was returned to warfarin therapy and their LFT values returned to baseline.

CONCLUSION

Studies have indicated a potential for reduced dabigatran efficacy with primidone due to P-glycoprotein induction, thereby potentiating the risk for thrombosis. To date, reports are lacking of this interaction resulting in hepatic injury. The present case suggests that this interaction may be clinically significant with regard to selection of antithrombotic medication therapy in patients on primidone therapy.

Novel Drug Interaction index and Risk of Mortality in Older Patients With Atrial Fibrillation Receiving Non Vitamin K Oral Anticoagulants (NOEL Drug)

Drug interactions with novel oral anticoagulants (NOACs) may decrease their advantages. We aimed to explore the drug interaction rates with NOACs and impacts of drug interaction index (DII) on mortality among older patients with atrial fibrillation (AF). In this retrospective cohort study, we enrolled 704 eligible patients aged 65≤ with AF between January 1, 2018 and December 30, 2019 in a tertiary outpatient cardiology clinic. We recorded demographic, clinical characteristics, and medications for the last 3 months. At the end of the evaluation visit (March 1, 2020), death events and dates were recorded. All medications were checked for drug interactions using Lexicomp® software. Each drug interaction was annotated according to risk grade. Moreover, we determined a new index ratio of C/D/X classes to total interactions called DII. The mean age was 75.19  ±  7.13 and 398 (56%) were male. Death events were observed in 106 (15%) patients. A total of 9883 drugs were analyzed for drug interactions. The majority of drug interactions were in class A (80.7%). Clinically relevant interactions were 14.6% (Class C/D/X). The area under receiver operating characteristic curve was 0.704 (95% confidence interval: 0.653-0.754) and 0.167 cutoff value (68.9% sensitivity and 80.2% specificity [3.11 positive likelihood ratio]) for DII to predict mortality. This study showed an overview of the NOACs interactions in older patients with AF. Additionally, the inappropriate NOAC dose and DII showed an association with mortality. NOAC treatment should be guided by drug interaction applications to reduce mortality.

Prediction of potential drug interactions between repurposed COVID-19 and antitubercular drugs: an integrational approach of drug information software and computational techniques data

Introduction:

Tuberculosis is a major respiratory disease globally with a higher prevalence in Asian and African countries than rest of the world. With a larger population of tuberculosis patients anticipated to be co-infected with COVID-19 infection, an ongoing pandemic, identifying, preventing and managing drug–drug interactions is inevitable for maximizing patient benefits for the current repurposed COVID-19 and antitubercular drugs.

Methods:

We assessed the potential drug–drug interactions between repurposed COVID-19 drugs and antitubercular drugs using the drug interaction checker of IBM Micromedex®. Extensive computational studies were performed at a molecular level to validate and understand the drug–drug interactions found from the Micromedex drug interaction checker database at a molecular level. The integrated knowledge derived from Micromedex and computational data was collated and curated for predicting potential drug–drug interactions between repurposed COVID-19 and antitubercular drugs.

Results:

A total of 91 potential drug–drug interactions along with their severity and level of documentation were identified from Micromedex between repurposed COVID-19 drugs and antitubercular drugs. We identified 47 pharmacodynamic, 42 pharmacokinetic and 2 unknown DDIs. The majority of our molecular modelling results were in line with drug–drug interaction data obtained from the drug information software. QT prolongation was identified as the most common type of pharmacodynamic drug–drug interaction, whereas drug–drug interactions associated with cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (P-gp) inhibition and induction were identified as the frequent pharmacokinetic drug–drug interactions. The results suggest antitubercular drugs, particularly rifampin and second-line agents, warrant high alert and monitoring while prescribing with the repurposed COVID-19 drugs.

Conclusion:

Predicting these potential drug–drug interactions, particularly related to CYP3A4, P-gp and the human Ether-à-go-go-Related Gene proteins, could be used in clinical settings for screening and management of drug–drug interactions for delivering safer chemotherapeutic tuberculosis and COVID-19 care. The current study provides an initial propulsion for further well-designed pharmacokinetic-pharmacodynamic-based drug–drug interaction studies.

Plain Language Summary

A Cautionary Tale of Triple Therapy

A 54-year-old man with a history of atrial flutter presented with anterior ST-segment elevation myocardial infarction complicated by cardiogenic shock and underwent percutaneous coronary intervention of the left main coronary artery. He was placed on triple antithrombotic therapy and ultimately recovered. However, before discharge, he developed hypotension, confusion, and hemiplegia. (Level of Difficulty: Beginner.)

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.

Updated recommendations for the treatment of venous thromboembolism

Venous thromboembolism (VTE), which includes pulmonary embolism and deep vein thrombosis, is a condition characterized by abnormal blood clot formation in the pulmonary arteries and the deep venous vasculature. It is often serious and sometimes even fatal if not promptly and appropriately treated. Moreover, the later consequences of VTE may result in reduced quality of life. The treatment of VTE depends on various factors, including the type, cause, and patient comorbidities. Furthermore, bleeding may occur as a side effect of VTE treatment. Thus, it is necessary to carefully weigh the benefits versus the risks of VTE treatment and to actively monitor patients undergoing treatment. Asian populations are known to have lower VTE incidences than Western populations, but recent studies have shown an increase in the incidence of VTE in Asia. A variety of treatment options are currently available owing to the introduction of direct oral anticoagulants. The current VTE treatment recommendation is based on evidence from previous studies, but it should be applied with careful consideration of the racial, genetic, and social characteristics in the Korean population.

Update on drug interactions with non-vitamin-K-antagonist oral anticoagulants for stroke prevention in elderly patients

Introduction: We update the knowledge, since the last review in 2017, about drug-drug interactions (DDI) of non-vitamin-K-antagonist oral anticoagulants (NOAC) in patients ≥75 years.Areas covered: The literature was searched for: 'dabigatran,' 'rivaroxaban,' 'edoxaban,' or 'apixaban' and drugs, affecting platelet function, CYP3A4-, CYP2C9-, or P-Gp-activity. Pharmacodynamic DDI of NOAC with drugs affecting platelet function like nonsteroidal anti-inflammatory drugs and antiplatelet agents occur most frequently. Pharmacokinetic DDI with NOAC were found for 37 of 117 drugs. Reports about DDI with NOAC were found for 51% of P-gp-affecting, 38% for CYP2C9-affecting and 27% for CYP3A4-affecting drugs. Reports about DDI of cardiovascular drugs with NOAC were the most prevalent, followed by anti-infective and nervous system drugs. NOAC plasma levels were measured in retrospective and cohort studies and were associated with concomitant medication. Reports about DDI of NOAC were found in 71 patients ≥75 years.Expert opinion: The knowledge about DDI of NOAC in elderly patients is very limited. Studies should be carried out to investigate the role of drugs potentially interacting with NOAC, which until now have not been investigated. When studying DDI of NOAC, care should be taken to include elderly patients with impaired renal function and patients on polymedication.

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.

Comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants and warfarin in older adults with atrial fibrillation and diabetes

OBJECTIVE

To evaluate comparative effectiveness and safety of non-vitamin-K antagonist oral anticoagulants (NOACs) versus warfarin in Medicare beneficiaries with non-valvular atrial fibrillation (NVAF) and comorbid diabetes mellitus (DM).

METHODS

A retrospective cohort study using 2014-2016 5% national Medicare data was undertaken. NVAF patients with DM aged ≥65 years having at least one prescription for NOACs or warfarin between July 2014 and December 2015 were included in the study. Propensity score matching was used to balance demographic and baseline clinical characteristics of patients in two treatment groups. Cardiovascular outcomes including stroke/systemic embolism (SE) and myocardial infarction (MI) were evaluated to measure effectiveness. Assessment of safety outcomes included intracranial hemorrhage (ICH), major gastrointestinal bleeding (MGB), bleeding from other sites (OB) and all-cause mortality. Stratified Cox proportional hazards models were used to estimate hazard ratios for the outcomes in the matched cohort.

RESULTS

The matched sample consisted of 4582 patients (2291 pairs). Compared to warfarin, NOACs had a significantly lower risk of stroke/SE (hazard ratio (HR): 0.373, 95% confidence interval (CI): 0.247-0.564, p < .001) and all-cause mortality (HR: 0.783, CI: 0.656-0.873, p = .007). NOACs were found to significantly reduce the risk of ICH (HR: 0.500, CI: 0.300-0.834, p = .008) and OB (HR: 0.608, CI: 0.424-0.870, p = .007), but no difference was observed in the risk of MGB (HR: 0.862, CI: 0.640-1.160, p = .326) between NOACs and warfarin. The composite outcome demonstrated superior overall effectiveness and safety of NOAC therapy compared to warfarin therapy (HR: 0.685, CI: 0.587-0.801, p < .001).

CONCLUSION

Oral anticoagulation therapy with NOACs was found to be more effective than warfarin therapy among older adults with NVAF and comorbid DM.

A Possible Drug-Drug Interaction Between Eliquis and Amiodarone Resulting in Hemopericardium

According to the ARISTOTLE trial, apixaban was superior to warfarin because it was associated with fewer strokes, systemic embolism, and bleeding. Hemopericardium was one of the major bleeding events reported in this trial. However, the percentage of patients that developed hemopericardium was not stated in the trial results.

We present a case of hemopericardium in an 80-year-old man admitted for dyspnea, cough, and lower extremity edema. He was recently diagnosed with paroxysmal atrial fibrillation and started on apixaban for stroke prevention. Prior to admission, he was taking metoprolol succinate and amiodarone for atrial fibrillation. His symptoms resolved after undergoing successful pericardiocentesis.

Although hemopericardium is a rare side effect associated with the use of non-vitamin K oral anticoagulants (NOACs), we suspect that a drug-drug interaction between apixaban and amiodarone (via the cytochrome p450 system and p-glycoprotein efflux pumps), the patient's advanced age, and borderline creatinine are possible risk factors.

Five-Year Trends in Potential Drug Interactions with Direct-Acting Oral Anticoagulants in Patients with Atrial Fibrillation: An Australian-Wide Study

Background: Co-prescribing medications that can interact with direct-acting oral anticoagulants (DOACs) may decrease their safety and efficacy. The aim of this study was to examine the co-prescribing of such medications with DOACs using the Australian national general practice dataset, MedicineInsight, over a five-year period. Methods: We performed five sequential cross-sectional analyses in patients with atrial fibrillation (AF) and a recorded DOAC prescription. Patients were defined as having a drug interaction if they had a recorded prescription of an interacting medication while they had had a recorded prescription of DOAC in the previous six months. The sample size for the cross-sectional analyses ranged from 5333 in 2014 to 19,196 in 2018. Results: The proportion of patients who had potential drug interactions with a DOAC decreased from 45.9% (95% confidence interval (CI) 44.6%–47.4%) in 2014 to 39.9% (95% CI 39.2%–40.6%) in 2018, p for trend < 0.001. During this period, the most frequent interacting class of medication recorded as having been prescribed with DOACs was selective serotonin/serotonin and norepinephrine reuptake inhibitor (SSRI/SNRI) antidepressants, followed by non-steroidal anti-inflammatory drugs (NSAIDs), calcium channel blockers (CCBs) and amiodarone. Conclusions: Overall, potential drug interactions with DOACs have decreased slightly over the last five years; however, the rate of possible interaction with SSRIs/SNRIs has remained relatively unchanged and warrants awareness-raising amongst prescribers.

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.

Concomitant Use of NSAIDs or SSRIs with NOACs Requires Monitoring for Bleeding

PURPOSE

Non-vitamin K antagonist oral anticoagulants (NOACs) are widely used in patients with atrial fibrillation (AF) because of their effectiveness in preventing stroke and their better safety, compared with warfarin. However, there are concerns for an increased risk of bleeding associated with concomitant use of non-steroidal anti-inflammatory drugs (NSAIDs) or selective serotonin reuptake inhibitors (SSRIs) with NOACs. In this study, we aimed to evaluate the risk of bleeding events in individuals taking concomitant NSAIDs or SSRIs with NOACs after being diagnosed with AF.

MATERIALS AND METHODS

A nested case-control analysis to assess the safety of NSAIDs and SSRIs among NOAC users with AF was performed using data from Korean National Health Insurance Service from January 2012 to December 2017. Among patients who were newly prescribed NOACs, 1233 cases hospitalized for bleeding events were selected, and 24660 controls were determined.

RESULTS

The risk of bleeding events was higher in patients receiving concomitant NSAIDs [adjusted odds ratio (aOR) 1.41; 95% confidence interval (CI) 1.24-1.61] or SSRIs (aOR 1.92; 95% CI 1.52-2.42) with NOACs, compared to no use of either drug, respectively. The risk of upper gastrointestinal bleeding was higher in patients receiving concomitant NSAIDs or SSRIs without proton pump inhibitors (PPIs) (NSAIDs: aOR 2.47; 95% CI 1.26-4.83, SSRI: aOR 10.8; 95% CI 2.41-2.48) compared to no use.

CONCLUSION

When NSAIDs or SSRIs are required for NOAC users with AF, physicians need to monitor bleeding events and consider the use of PPIs, especially for combined use of both drugs or when initiating NOACs treatment.

Direct oral anticoagulants in patients with hematologic malignancies

The anticoagulant treatment for patients with hematologic malignancies is low molecular weight heparin (LMWH), which is considered the safest in this particular patients setting. Although direct oral anticoagulants (DOACs) have proven their efficacy and safety in patients with cancer, their use can be challenging in patients with hematologic malignancies due to the peculiarity of these neoplasms: high thrombotic risk, possible onset of thrombocytopenia and concomitant anticancer therapies. The aim of our study was to evaluate the efficacy and safety of DOACs for venous thromboembolism or atrial fibrillation in patients with hematologic malignancies and plasmatic DOACs level during anticancer therapy and at time of bleeding or thrombotic complications. We evaluated patients with hematologic malignancies treated with DOACs for venous thromboembolism or atrial fibrillation-therapy was maintained until the platelet count was ≥50 × 10⁹ /L. In case of concomitant anticancer treatment and haemorrhagic or thrombotic events, we checked DOACs plasma levels (trough and peak). The patients evaluated were 135: 104/135 were on anticancer therapy. We did not observe either thrombotic or major haemorrhagic adverse events. Minor bleedings occurred in 10 patients and clinical relevant non-major (CRNM) in two patients. There was a statistically significant correlation between bleedings and myelodysplastic syndrome. DOACs resulted effective and safe in patients with hematologic malignancies. DOACs plasma level can be helpful in suggesting an early dose adjustment to prevent haemorrhagic adverse event in patients on concomitant anticancer therapy. Larger prospective studies including hematologic patients are warranted to confirm the safety and efficacy of DOACs.

Real-World Analysis of Potential Pharmacokinetic and Pharmacodynamic Drug Interactions with Apixaban in Patients with Non-Valvular Atrial Fibrillation

Purpose

We conducted this study to assess the real-world prevalence, nature, predictors, and clinical necessity of apixaban pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions in patients with non-valvular atrial fibrillation (NVAF) at a tertiary medical institution in Saudi Arabia.

Patients and Methods

An observational retrospective cohort analysis was conducted in adult patients diagnosed with NVAF receiving apixaban for stroke prevention from the period of June 2015 to May 2019.

Results

Of the 1271 patients included in the analysis, 611 (48.1%) patients had potential PD– or PK–drug interactions with apixaban. Of those, 490 (38.6%) patients had potential PD drug–drug interactions (DDIs) and 121 (9.5%) patients had potential PK-DDIs. PD-DDIs with apixaban were mainly with antiplatelet therapy followed by non-steroidal anti-inflammatory drugs and antidepressants. PK-DDIs with apixaban were mainly with combined P-gp/CYP3A4 inhibitors or inducers. History of minor bleeding was positively correlated with PD-DDIs with apixaban, ß coefficient = 0.455 (OR 1.58; 95% CI 1.01–2.45); p<0.05. History of acute coronary syndrome was positively correlated with PD-DDIs with apixaban, ß coefficient = 0.515 (OR 1.60; 95% CI 1.36–1.99); p<0.05. History of heart failure was positively correlated with PK-DDIs with apixaban, ß coefficient = 0.459 (OR 1.58; 95% CI 1.07–2.35); p<0.05. Almost 15% of the included patients had no clinical indication to receive the potential interacting drug with apixaban and about 20% of them were assuming an inappropriate apixaban dose according to the product package insert.

Conclusion

Pharmacodynamics and pharmacokinetics interactions are common in more than half of the patients with NVAF receiving apixaban for stroke prevention in this real-world analysis. Some of these interacting medications are not indicated. Drug–drug interactions should always be considered and monitored with apixaban with a regular assessment of the need for any interacting medication.

Moving towards ideal and appropriate models of anticoagulation management service

It is now known that thrombotic disorders such as venous thromboembolism, ischemic stroke, and myocardial infarction contribute significantly to global morbidity and mortality. Anticoagulation service must respond to this new development. Warfarin has continued to provide the backbone for anticoagulation service for decades but with considerable drawbacks. The introduction of nonVitamin K oral anticoagulants (NOACs) has created new challenges. This article seeks to discuss how the establishment of appropriate models of anticoagulation could contain the draw backs of the old anticoagulants and improve on the compliance, availability, affordability, and accessibility of newer anticoagulants. Successful anticoagulation has always been defined by a scientific balancing of the risk of thrombosis and the complication of hemorrhage. To be able to maintain such optimal anticoagulation requires rational drug prescription (physician factor), institutelization of monitoring of therapy (anticoagulation clinic factor) as well as active participation of patients receiving therapy (patient factor). New models of service can be created out of this triad in a bid to replace the old routine medical care model. New models of anticoagulation service should include appropriately trained professionals such as Physicians, Pharmacists, Clinical Pharmacologists, Nurses, and Laboratory Scientists who are knowledgeable in diagnostic, management, and monitoring of anticoagulation. The different models of anticoagulation service discussed in this article clearly demonstrate the need for restructuring of this life saving service particularly in the era of NOAC. Newer models of care that should provide safe, efficacious, and cost-effective services are needed.

Efficacy and Safety of Direct-Acting Oral Anticoagulants (DOACs) in the Overweight and Obese

Obesity plays an essential role in the safety of pharmacologic drugs. There is paucity of data for direct oral anticoagulants (DOACs) in the obese, despite these agents becoming more widely used. The primary and secondary objectives of this study were to assess the safety and efficacy of DOACs in the overweight and obese populations when used for primary prophylaxis in the setting of non-valvular atrial fibrillation (NVAF) and for treatment of venous thromboembolisms (VTE). We conducted a retrospective cohort study in a large tertiary care center and obtained data through review of electronic health records. Among patients with NVAF and VTE on apixaban, there were no differences in rates of major bleeding (MB) and clinically relevant nonmajor bleeding (CRNMB) in the overweight and obese populations when compared to normal weight and underweight individuals. The multivariate adjusted analysis for rivaroxaban found that the odds of CRNMB for patients with BMI <25 was 5.37 (95% CI 1.50–19.32) times higher than that of BMI ≥25. Moreover, patients on medications that had known interactions with DOACs had 6.40 times higher odds of CRNMB than patients without such interactions (95% CI 1.49–27.57), which was not accounted for by the effects of aspirin and plavix alone. Efficacy was similar between all weight groups, for both apixaban and rivaroxaban. These results support previous analyses preformed in the large phase III trials and confirm that apixaban and rivaroxaban are safe in the overweight and obese.

P2Y12 inhibitors with oral anticoagulation for percutaneous coronary intervention with atrial fibrillation: a systematic review and meta-analysis

OBJECTIVE

This study aimed to compare the safety and efficacy of third-generation P2Y12 inhibitors versus clopidogrel in combination with oral anticoagulation (OAC) with or without aspirin in patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI).

METHODS

We performed a systematic review including both prospective and retrospective studies that compared dual and triple antithrombotic regimens for bleeding and major adverse cardiac events (MACE) in patients with AF undergoing PCI. We analysed rates of bleeding and MACE by P2Y12 inhibitor choice. Risk ratio (RR) 95% CIs were measured using the Mantel-Haenszel method. Where study heterogeneity was low (I2 <25%), we used the fixed effects model, otherwise the random effects model was used.

RESULTS

A total of 22 014 patients were analysed from the seven studies included. Among patients treated with both OAC and P2Y12 inhibitor with or without aspirin, 90% (n=9708) were treated with clopidogrel, 8% (n=830) with ticagrelor, and 2% (n=191) with prasugrel. When compared with clopidogrel, use of ticagrelor (RR 1.36; 95% CI 1.18 to 1.57) and prasugrel (RR 2.11; 95% CI 1.34 to 3.30) were associated with increased rates of bleeding. Compared with clopidogrel, there were no significant differences in rates of MACE with ticagrelor (RR 1.03; 95% CI 0.65 to 1.62) or prasugrel (RR 1.49; 95% CI 0.69 to 3.24).

CONCLUSION

Based on this meta-analysis, the use of clopidogrel is associated with a lower rate of bleeding compared with ticagrelor or prasugrel in patients with AF on OAC undergoing PCI.

Bullous pemphigoid-like skin rash associated with Rivaroxaban use in a very elderly patient with multimorbidity and chronic kidney disease: A case report

Direct oral anticoagulants (DOACs) are increasingly being used in the elderly population in view of its ease of use, efficacy, and favorable side-effect profile compared with the vitamin K antagonists. However, there is a need for increase awareness of well-characterized cases, albeit a small number, of bullous pemphigoid-like skin reactions associated with rivaroxaban.

Precision dosing to avoid adverse drug reactions

Adverse drug reactions (ADRs) have traditionally been managed by trial and error, adjusting drug and dose selection reactively following patient harm. With an improved understanding of ADRs, and the patient characteristics that increase susceptibility, precision medicine technologies enable a proactive approach to ADRs and support clinicians to change prescribing accordingly. This commentary revisits the famous pharmacology–toxicology continuum first postulated by Paracelsus 500 years ago and explains why precision dosing is needed to help avoid ADRs in modern clinical practice. Strategies on how to improve precision dosing are given, including more research to establish better precision dosing targets in the cases of greatest need, easier access to dosing instructions via e-prescribing, improved monitoring of patients with novel biomarkers of drug response, and further application of model-informed precision dosing.

Clinically relevant drug interactions between newer antidepressants and oral anticoagulants

Introduction: This is a review of the drug interactions (DIs) between newer antidepressants and oral anticoagulants (OACs): vitamin K antagonists (VKAs) and direct-acting OACs (DOACs).Areas covered: Articles were obtained from PubMed searches performed for each of the newer antidepressants and oral anticoagulants. The basic pharmacokinetic and pharmacodynamic mechanisms for DIs with these drugs were summarized. Some newer antidepressants are inhibitors of a number of cytochrome P450 (CYP) isoforms and many antidepressants appear to have potential to impair serotonin platelet function and increase bleeding risk.Expert opinion: Clinicians should not forget that the DIs between newer antidepressants and VKAs can be potentially lethal. Among SSRIs, fluoxetine and fluvoxamine appear to be associated with the highest DI risk with warfarin, the most commonly prescribed VKA worldwide. Case reports featuring duloxetine, mirtazapine and trazadone suggested potential for interaction with warfarin. As CYP3A4 is an important metabolic pathway for all DOACs except dabigatran, it appears reasonable to recommend avoiding the co-prescription of fluoxetine and fluvoxamine (weak to moderate CYP3A4 inhibitors) and St John's wort (CYP3A4 inducer). Many package inserts for the newer antidepressants include a warning regarding an increased risk of bleeding events with concomitant use of these agents with OACs.

Pharmacogenomic phase transition from personalized medicine to patient-centric customized delivery

Personalized medicine has been a booming area in clinical research for the past decade, in which the detailed information about the patient genotype and clinical conditions were collected and considered to optimize the therapy to prevent adverse reactions. However, the utility of commercially available personalized medicine has not yet been maximized due to the lack of a structured protocol for implementation. In this narrative review, we explain the role of pharmacogenetics in personalized medicine, next-generation personalized medicine, i.e., patient-centric personalized medicine, in which the patient's comfort is considered along with pharmacogenomics to be a primary factor. We extensively discuss the classifications, strategies, tools, and drug delivery systems that can support the implementation of patient-centric personalized medicine from an industrial perspective.

A New Test for the Detection of Direct Oral Anticoagulants (Rivaroxaban and Apixaban) in the Emergency Room Setting

Determining whether a patient has taken a direct oral anticoagulant (DOAC) is critical during the periprocedural and preoperative period in the emergency department. However, the inaccessibility of complete medical records, along with the generally inconsistent sensitivity of conventional coagulation tests to these drugs, complicates clinical decision making and puts patients at risk of uncontrollable bleeding. In this study, we evaluate the utility of inhibitor-II-X (i-II-X), a novel, microfluidics-based diagnostic assay for the detection and identification of Factor Xa inhibitors (FXa-Is) in an acute care setting.

DESIGN

First-in-human, 91-patient, single-center retrospective pilot study.

SETTING

Emergency room.

PATIENTS

Adult patients admitted into the emergency department, which received any clinician-ordered coagulation test requiring a 3.2% buffered sodium citrate blood collection tube.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma samples from patients admitted to the emergency department were screened for the use of FXa-Is, including apixaban and rivaroxaban, within the past 24 hours using our new i-II-X microfluidic test. i-II-X results were then compared with results from conventional coagulation tests, including prothrombin time (PT) and international normalized ratio (INR), which were ordered by treating clinicians, and an anti-Xa assay for rivaroxaban. The i-II-X test detected DOACs in samples collected from the emergency department with 95.20% sensitivity and 100.00% specificity. Unlike PT and INR, i-II-X reliably identified patients who had prolonged clotting times secondary to the presence of a FXa-I.

CONCLUSIONS

The i-II-X test overcomes the limitations of currently available coagulation tests and could be a useful tool by which to routinely screen patients for DOACs in emergency and critical care settings. Our new diagnostic approach is particularly relevant in clinical situations where medical records may be unavailable, or where precautions need to be taken prior to invasive interventions, such as specific reversal agent administration.

Prediction of Drug-Drug Interactions Related to Inhibition or Induction of Drug-Metabolizing Enzymes

Drug-drug interaction (DDI) is the phenomenon of alteration of the pharmacological activity of a drug(s) when another drug(s) is co-administered in cases of so-called polypharmacy. There are three types of DDIs: pharmacokinetic (PK), pharmacodynamic, and pharmaceutical. PK is the most frequent type of DDI, which often appears as a result of the inhibition or induction of drug-metabolising enzymes (DME). In this review, we summarise in silico methods that may be applied for the prediction of the inhibition or induction of DMEs and describe appropriate computational methods for DDI prediction, showing the current situation and perspectives of these approaches in medicinal and pharmaceutical chemistry. We review sources of information on DDI, which can be used in pharmaceutical investigations and medicinal practice and/or for the creation of computational models. The problem of the inaccuracy and redundancy of these data are discussed. We provide information on the state-of-the-art physiologically- based pharmacokinetic modelling (PBPK) approaches and DME-based in silico methods. In the section on ligand-based methods, we describe pharmacophore models, molecular field analysis, quantitative structure-activity relationships (QSAR), and similarity analysis applied to the prediction of DDI related to the inhibition or induction of DME. In conclusion, we discuss the problems of DDI severity assessment, mention factors that influence severity, and highlight the issues, perspectives and practical using of in silico methods.

Safety and efficacy of direct oral anticoagulants for venous thromboembolism and stroke prophylaxis in patients with hematologic malignancies

Purpose

Low-molecular-weight heparins are currently the recommended antithrombotic therapy for treatment and prevention of malignancy-related venous thromboembolism. Currently, the evidence evaluating direct oral anticoagulants versus low-molecular-weight heparins or a vitamin K antagonist in cancer patients with hematologic malignancies is limited. We evaluated the safety and efficacy of direct oral anticoagulants for venous thromboembolism treatment or stroke prevention for non-valvular atrial fibrillation in patients with hematologic malignancies.

Methods

This was a retrospective evaluation of adult patients with hematologic malignancies who received at least one dose of the Food and Drug Administration-approved direct oral anticoagulant for venous thromboembolism treatment or stroke prevention. We determined the frequency of major bleeding events, non-major bleeding events, stroke, systemic embolism, appropriateness of initial direct oral anticoagulant doses, holding practices prior to procedures, and the rate of all-cause mortality. An analysis was also performed to compare the incidence of bleeding between patients with a history of hematopoietic stem cell transplant to non-transplant patients.

Results

A total of 103 patients were identified, with the majority of patients receiving rivaroxaban for venous thromboembolism treatment. Major bleeding events occurred in four patients and no fatal bleeding events occurred. Non-major bleeding occurred in 29 patients, most commonly epistaxis and bruising. Two patients experienced a systemic embolism while on direct oral anticoagulant therapy.

Conclusion

Direct oral anticoagulants may be a safe and effective alternative for anticoagulation therapy in patients with hematologic malignancies. However, larger prospective studies comparing direct oral anticoagulants to low-molecular-weight heparins or vitamin K antagonists are warranted to compare efficacy and safety outcomes in this patient population.

Patient-focused interventions to support vulnerable people using oral anticoagulants: a narrative review

The aim of this review was to identify patient-focused interventions that have been trialed to support vulnerable patient populations taking oral anticoagulants (warfarin and the direct-acting oral anticoagulants (DOACs)) such as older persons (65 years and over), those with limited health literacy, and those from culturally and linguistically diverse (CALD) backgrounds. This review also aimed to report on the effects of these interventions on outcomes relevant to the use of anticoagulant therapy. Original articles published between 1 January 1995 and 30 June 2017 were identified using several electronic databases such as Medline, Ovid, Embase, Scopus, Cochrane, and Google Scholar. The following terms were used for the three-tiered search: Tier 1, elderly, aged, older adult, geriatrics; Tier 2, health literacy, literacy, low health literacy, low English proficiency, patient literacy; and Tier 3, ethnicity, ethnic, ethnic groups, CALD, culturally and linguistically diverse, NESB, non-English speaking background, race, racial groups, religion, religious groups, and minority groups. The terms for each tier were combined with the following terms: anticoagulants, anticoagulation, warfarin, apixaban, dabigatran, rivaroxaban, DOACS, new oral anticoagulants, novel oral anticoagulants, patient care, patient knowledge, comprehension, patient education, patient participation, and communication. A total of 41 studies were identified. Most of the interventions identified included older persons taking warfarin who were monitored using the international normalized ratio (INR) and who received patient education. Many interventions reported a significant positive impact on patients' knowledge, reduction in the number of adverse events caused by hemorrhage, and better INR control. More research on patient-focused interventions is needed that includes patients with limited health literacy, those from CALD backgrounds, and family members and caregivers of patients taking oral anticoagulants.

Prevention and Treatment of Acute Stroke in the Nonagenarians and Beyond: Medical and Ethical Issues

PURPOSE OF REVIEW

As one of the fastest growing portions of the population, nonagenarians will constitute a significant percentage of the stroke patient population in the near future. Nonagenarians are nevertheless not specifically targeted by most clinical guidelines. In this review, we aimed to summarise the available evidence guiding stroke prevention and treatment in this age group.

RECENT FINDINGS

Several recent observational studies have shown that the benefits of anticoagulation for the oldest old patients with atrial fibrillation may outweigh the bleeding risk. A sub-analysis of the IST-3 trial has shown for the first time that thrombolysis treatment in acute ischaemic stroke may be beneficial and safe even in octogenarian patients and older. Several recent observational studies have assessed thrombolysis in nonagenarians. The latest of these has shown better disability outcomes without increased rates of symptomatic intracerebral haemorrhage with thrombolysis. Nonagenarian stroke patients may benefit from similar preventative and therapeutic strategies as their younger counterparts. A few important exceptions include primary prevention using aspirin or statins. Patient selection is nevertheless essential given the increased adverse event rates. Patient preference should play a key role in the decision-making process. Clinical trials including more nonagenarian patients are required to yield more robust evidence.

Preventable Cases of Oral Anticoagulant-Induced Bleeding: Data From the Spontaneous Reporting System

Background

Despite the risk of bleeding is a well-known adverse effect of oral anticoagulants, there is scarce evidence on the preventability of oral anticoagulant-induced bleedings. Therefore, we investigated the potential risk factors related to preventable cases of oral anticoagulant-induced bleedings.

Methods

We performed a study using Individual Case Safety Reports (ICSRs) with an oral anticoagulant as suspected drug among those reported through the spontaneous reporting system of Campania Region from 1 July 2012 to 31 December 2017. The P-method was used for the preventability assessment of all cases of bleeding.

Results

In total, 58 cases out of 253 (22.9%) were preventable, and the most reported suspected drug was an indirect oral anticoagulant (warfarin). Sixty-eight critical criteria for preventability were identified, all related to healthcare professionals' practices. The most detected risk factor related to healthcare professionals' practices was the labeled drug-drug interaction for both direct and indirect oral anticoagulants.

Conclusion

Our findings describe the most reported risk factors for preventability of oral anticoagulant-induced bleedings. These factors may be useful for targeting interventions to improve pharmacovigilance activities in our regional territory and to reduce the burden of medication errors and inappropriate prescription.

Safety of concomitant treatment with Non-Vitamin K Oral Anticoagulants and SSRI/SNRI antidepressants

Introduction: Warfarin has been considered as a “gold standard” in the prevention and treatment of thromboembolic events since 1954. Since the introduction of direct oral anticoagulants in the last few years (NOAC-Non-Vitamin K antagonist Oral Anticoagulants) prescriptions volume for apixaban, edoxaban, dabigatran and rivaroxaban have been gradually surpassing warfarin. The benefits include: anticoagulation from day one, fixed daily dosing, elimination for the need of international normalised ratio (INR) monitoring, fewer interactions with food and co-administered medicines with reduced risk of bleeding and better overall life quality.

Objectives: Assessing evidence for the safe use of Non-vitamin K Oral Anticoagulants (NOAC) with Selective Serotonin Reuptake Inhibitors (SSRI) and Serotonin and Noradrenaline Reuptake Inhibitors (SNRI).

Method: Review of literature published between 2014 and 2016 was made using the key words: Selective Serotonin Reuptake Inhibitor, Serotonin and Noradrenaline Reuptake Inhibitors, apixaban, dabigatran, edoxaban, rivaroxaban, bleeding, interaction, depression with time description from 2014 to 2018. Evidence within the literature was then compared with guidelines from the National Institute for Health and Care Excellence (UK), British National Formulary (UK), Clinical Excellence Commission (Australia), Thrombophilia and Anticoagulation Clinic (USA) and Summaries of Product Characteristics (SPC).

Results: 1. Serotonin plays a critical role in maintaining homeostasis. Use of SSRI/SNRI compromises its platelet reuptake increasing risk of bleeding. 2. Increased tolerability and safety of NOAC over Warfarin, although caution is advised when NOAC is used with SSRI/SNRI with less evidence suggesting pharmacodynamic interactions. 3. It is not recommended to use NOAC with strong CYP and P-gp inhibitors.

Conclusions: With limited literature evidence, caution is advised when co-prescribed NOACs with SSRI/SNRI, especially with other cofactors and interacting medicines further increasing risk of bleeding.

Evaluation of Potential Drug-Drug Interactions With Direct Oral Anticoagulants in a Large Urban Hospital

OBJECTIVE

The aim of this study is to assess patterns of potential drug-drug interactions (DDIs) with direct oral anticoagulants (DOACs) in an inpatient hospital setting.

METHODS

A retrospective chart review was conducted at the Brookdale University Hospital and Medical Center (BUHMC) from January 2014 to November 2016. All adult patients admitted to the BUHMC who were treated with a DOAC for at least 3 days were screened. Among them, those who received selected interacting drugs at any time during the course of DOAC therapy were included in this study.

RESULTS

This study included 165 patients with an average of 73 years (standard deviation [SD] = 12.3) and 233 cases. The most commonly used concomitant drug with a DOAC was aspirin (58%), followed by amiodarone (16%) and P2Y₁₂ inhibitors (11%). The combined use of dual antiplatelet therapy and a DOAC was identified in 18 (6%) cases. Approximately one-third of the cases encountered were classified as the "avoidance" category.

CONCLUSIONS

Despite computerized DDI alerts, potentially significant DDIs with DOACs still occur. While the present study provides insight into the current patterns of DDIs, further studies are needed to evaluate clinical outcomes of the potential DDIs with DOACs in practice.