Clinical Management of Pharmacokinetic Drug Interactions with Direct Oral Anticoagulants (DOACs)

Effect of the frequently used antiepileptic drugs carbamazepine, gabapentin, and pregabalin on the pharmacokinetics of edoxaban and other oral factor xa inhibitors in healthy volunteers

Purpose

Pregabalin, gabapentin, and carbamazepine, a potent inducer of cytochrome P450 (CYP) 3A4 and P-glycoprotein, are frequently used antiepileptic drugs that are often administered together with factor Xa inhibitors (FXaI). We aimed to investigate whether potentially clinically relevant drug-drug interactions occur with these combinations.

Methods

In an open-label fixed-sequence trial in 36 healthy volunteers, we evaluated the pharmacokinetics of 60 mg edoxaban and of a microdosed FXaI cocktail (25 µg apixaban, 50 µg edoxaban, and 25 µg rivaroxaban) before and during treatment with carbamazepine (12 evaluable volunteers, individually dosed to therapeutic concentrations), gabapentin (11 volunteers, titrated to 3 × 400 mg/d), and pregabalin (12 volunteers, titrated to 2 × 300 mg/d). The antiepileptics were dosed to steady-state and the CYP3A activity was evaluated by assessing the pharmacokinetics of microdosed midazolam (30 µg).

Results

Carbamazepine reduced the area under the plasma concentration-time curve (AUC ∞ ) of 60 mg edoxaban by a factor of 0.48 (geometric mean ratio (GMR) with 90% CI (0.41-0.56); p < 0.0001) and Cmax by a factor of 0.47 (0.34-0.66) and reduced the exposure of the edoxaban metabolite M-4 to a similar extent. Carbamazepine also decreased the exposure (AUC ∞ ) of microdosed apixaban, edoxaban, and rivaroxaban by a factor of 0.66, 0.59, and 0.56, respectively. Gabapentin and pregabalin did neither affect the exposure of 60 mg edoxaban nor the exposure of any microdosed FXaI.

Conclusion

Carbamazepine decreased FXaI exposure to a clinically relevant extent and dose adjustment may be required to maintain an adequate anticoagulant effect, whereas gabapentin and pregabalin do not require dose adjustment of FXaI.

Critical considerations for co-administering rivaroxaban and vonoprazan: Unveiling potential pharmacokinetic interactions

To study the effects of metabolic enzyme activity inhibition and genetic polymorphisms on the pharmacokinetics and pharmacodynamics of rivaroxaban, we established an in vitro enzymatic reaction system to screen for inhibitors, and used the UPLC-MS/MS method to detect the levels of rivaroxaban and its metabolite M2-1. Additionally, in vivo pharmacokinetic-pharmacodynamic studies were conducted using Sprague-Dawley rats. Human recombinant CYP2J2 baculosomes were prepared using a baculovirus-insect expression system to investigate the impact of genetic polymorphisms on rivaroxaban metabolism through enzyme kinetics methods. The results demonstrated that acid-suppressing drugs strongly inhibited the metabolism of rivaroxaban in vitro. Among them, vonoprazan significantly increased the systemic exposure of rivaroxaban in vivo, while also prolonging prothrombin time, likely due to the competitive binding of vonoprazan and rivaroxaban to CYP2J2. Moreover, the genetic polymorphisms of CYP2J2 determined the metabolic characteristics of rivaroxaban and the inhibitory potency of vonoprazan. Overall, our findings suggest that vonoprazan-induced inhibition of CYP2J2 activity can affect the pharmacokinetics and pharmacodynamics of rivaroxaban, with the extent of inhibition determined by the genetic polymorphism of CYP2J2. These insights have important implications for the precise management of rivaroxaban in humans.

Novel Drug-Drug Interaction of Potential Rifabutin-Induced Edoxaban Failure: A Case Report

Purpose: To report an incident of a breakthrough deep vein thrombosis (DVT) and potential example of a drug-drug interaction in a patient treated with edoxaban and rifabutin who was being treated for respiratory tuberculosis. Case: A 76-year-old male presented with anemia requiring transfusion and subsequent shortness of breath that was later diagnosed to be respiratory tuberculosis. He experienced a prolonged hospital stay due to persistently positive Mycobacterium tuberculosis respiratory samples and a complicated social situation that required continuous hospitalization for approximately five months. During his treatment the patient was transitioned from apixaban to edoxaban due to a drug-drug interaction with rifabutin. He subsequently had a DVT while on edoxaban after two months of therapy that would require him to transition to warfarin. Conclusion: This case represents an example of a potentially significant drug-drug interaction between edoxaban and rifabutin. Other direct oral anticoagulants (DOACs) exhibit a potential drug-drug interaction that limit their effectiveness when used with rifamycins. This report describes the first known case of a patient experiencing a DVT after prolonged edoxaban use in combination with rifabutin. Treatment with DOACs for patients taking concomitant cytochrome P450 (CYP) inducers such as rifabutin may be more complicated than previously believed.

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.

Time Course of the Interaction Between Oral Short-Term Ritonavir Therapy with Three Factor Xa Inhibitors and the Activity of CYP2D6, CYP2C19, and CYP3A4 in Healthy Volunteers

BACKGROUND

We investigated the effect of a 5-day low-dose ritonavir therapy, as it is used in the treatment of COVID-19 with nirmatrelvir/ritonavir, on the pharmacokinetics of three factor Xa inhibitors (FXaI). Concurrently, the time course of the activities of the cytochromes P450 (CYP) 3A4, 2C19, and 2D6 was assessed.

METHODS

In an open-label, fixed sequence clinical trial, the effect and duration of a 5-day oral ritonavir (100 mg twice daily) treatment on the pharmacokinetics of three oral microdosed FXaI (rivaroxaban 25 µg, apixaban 25 µg, and edoxaban 50 µg) and microdosed probe drugs (midazolam 25 µg, yohimbine 50 µg, and omeprazole 100 µg) was evaluated in eight healthy volunteers. The plasma concentrations of all drugs were quantified using validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods and pharmacokinetics were analysed using non-compartmental analyses.

RESULTS

Ritonavir increased the exposure of apixaban, edoxaban, and rivaroxaban, but to a different extent the observed area under the plasma concentration-time curve (geometric mean ratio 1.29, 1.46, and 1.87, respectively). A strong CYP3A4 inhibition (geometric mean ratio > 10), a moderate CYP2C19 induction 2 days after ritonavir (0.64), and no alteration of CYP2D6 were observed. A CYP3A4 recovery half-life of 2.3 days was determined.

CONCLUSION

This trial with three microdosed FXaI suggests that at most the rivaroxaban dose should be reduced during short-term ritonavir, and only in patients receiving high maintenance doses. Thorough time series analyses demonstrated differential effects on three different drug-metabolising enzymes over time with immediate profound inhibition of CYP3A4 and only slow recovery after discontinuation.

CLINICAL TRIAL REGISTRATION

EudraCT number: 2021-006643-39.

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.

Management of Patients Treated with Direct Oral Anticoagulants in Clinical Practice and Challenging Scenarios

It is well established that direct oral anticoagulants (DOACs) are the cornerstone of anticoagulant strategy in atrial fibrillation (AF) and venous thromboembolism (VTE) and should be preferred over vitamin K antagonists (VKAs) since they are superior or non-inferior to VKAs in reducing thromboembolic risk and are associated with a lower risk of intracranial hemorrhage (IH). In addition, many factors, such as fewer pharmacokinetic interactions and less need for monitoring, contribute to the favor of this therapeutic strategy. Although DOACs represent a more suitable option, several issues should be considered in clinical practice, including drug-drug interactions (DDIs), switching to other antithrombotic therapies, preprocedural and postprocedural periods, and the use in patients with chronic renal and liver failure and in those with cancer. Furthermore, adherence to DOACs appears to remain suboptimal. This narrative review aims to provide a practical guide for DOAC prescription and address challenging scenarios.

[Proper use of oral anticoagulants in the elderly patient]

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

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.

Anticoagulation for Atrial Fibrillation in Patients with Decompensated Liver Cirrhosis: Bold and Brave?

Atrial fibrillation is frequently diagnosed in patients with liver cirrhosis, especially in those with non-alcoholic steatohepatitis or alcoholic etiology. Anticoagulant treatment is recommended for thromboembolic protection in patients with atrial fibrillation. Considering the impaired coagulation balance in liver cirrhosis, predisposing patients to bleed or thrombotic events, the anticoagulant treatment is still a matter of debate. Although patients with liver cirrhosis were excluded from the pivotal studies that confirmed the efficacy and safety of the anticoagulant treatment in patients with atrial fibrillation, data from real-life cohorts demonstrated that the anticoagulant treatment in patients with liver cirrhosis could be safe. This review aimed to evaluate the recent data regarding the safety and efficacy of anticoagulant treatment in patients with decompensated liver cirrhosis. Direct oral anticoagulants are safer than warfarin in patients with compensated liver cirrhosis. In Child-Pugh class C liver cirrhosis, direct oral anticoagulants are contraindicated. New bleeding and ischemic risk scores should be developed especially for patients with liver cirrhosis, and biomarkers for bleeding complications should be implemented in clinical practice to personalize this treatment in a very difficult population represented by decompensated liver cirrhosis patients.

Effect of Genotype on the Pharmacokinetics and Bleeding Events of Direct Oral Anticoagulants: A Systematic Review and Meta-analysis

This meta-analysis aimed to investigate the effect of the genotype on the pharmacokinetics and bleeding events of direct oral anticoagulants (DOACs) and comprehensively searched electronic databases. Weighted mean difference (WMD) was used to assess the kinetic indicators, odds ratio, and 95% confidence interval (CI) were used to calculate the clinical outcomes. Thirteen articles with 1543 participants were finally included in this study. The peak concentration (C_max ) and area under the plasma concentration-time curve from time 0 to infinity of individuals with the ABCB1 rs 1045642 CT + TT were higher than that of the CC (WMD = -31.9, 95% CI [-49.94, -12.24], P = .02; WMD = -79.97, 95%CI [-152.38 to -7.56], P = .03, I² = 0). The C_max of individuals with mutated genes in ABCB1 2677-3435 is higher than that the wild type (WMD = -19.20, 95%CI [36.62 to -1.79], P = .03, I² = 0). Carriers of the CYP3A5 rs776746 GG genotype had a higher C_max than the GA gene (WMD = -51.22, 95%CI [-92.26 to -10.19], P = .01, I² = 0). Bleeding events were more common in the CES1 rs 2244613 AA + AC than in the CC (odds ratio, 2.62, 95%CI [1.06, 6.47], P = .04; I² = 0). The C_max of DOACs was affected by individuals with ABCB1 rs 1045642, ABCB1 2677-343, and cytochrome P450 3A5 rs 776746. Carriers of the ABCB1 rs 1045642 affected the change of area under the plasma concentration-time curve from time 0 to infinity of DOACs. Bleeding events were affected by CES1 rs 2244613.

Frailty as a Marker for the Plasma Concentrations of Direct Oral Anticoagulants in Older Patients: Results of an Exploratory Study

BACKGROUND

Frailty makes older adults vulnerable to adverse health outcomes and can modify pharmacokinetics and drug exposure.

OBJECTIVE

We aimed to explore the relationship between different frailty assessments and trough plasma concentrations of direct oral anticoagulants in older patients.

METHODS

The frailty status of adults aged ≥ 70 years receiving regular direct oral anticoagulant medication was assessed by four different instruments: Fried physical phenotype, Rockwood frailty index, Short Physical Performance Battery, and FRAIL scale. The two performance measures "slow gait speed" and "weak grip strength" were used to build a separate score depending on the number of positive criteria (none, one, two). For each participant, a single steady-state direct oral anticoagulant trough plasma concentration was collected, dose-normalized, and its relationship to the various frailty assessments analyzed.

RESULTS

Forty-two participants completed the study, with most using apixaban (n = 22). Dose-normalized apixaban trough concentrations were 2.48-fold higher in frail participants (Fried phenotype) than in robust participants (p = 0.009) and correlated positively with Fried physical phenotype (r_s = 0.535, p = 0.010) and negatively with Short Physical Performance Battery (r_s = - 0.434, p = 0.044). Compared with participants who met none of the criteria "slow gait speed" and "weak grip strength", apixaban trough concentrations were approximately 1.9-fold higher in participants who were positive for one (p = 0.018) or two (p = 0.013) of these measures.

CONCLUSIONS

In this exploratory study, higher levels of frailty on performance-based frailty assessments were associated with higher apixaban exposure in older adults.

CLINICAL TRIAL REGISTRATION

German Clinical Trials Register DRKS00016741; registered 20 February, 2019.

Trends of use and factors that determine the choice of oral anticoagulants in women and men with atrial fibrillation

The aim was to identify sex-specific factors linked with oral anticoagulant initiation in a cohort of patients with atrial fibrillation using administrative data from Quebec (Canada) between 2014 and 2017. Cohort entry defined as new users, that is, no claims in last 12 months, a cohort of 32 050 patients was stratified in two groups, that is, women and men. Multivariable regression models were used to identify factors of initiations for low- and standard-dose direct oral anticoagulants (DOACs) versus warfarin, and low- versus standard-dose DOACs. In both sexes, warfarin initiation decreased and DOAC initiation increased, with year of initiation as major factors of DOACs use. In 2017, the increase was of 2- to 4-fold and 3- to 8-fold for low- and standard-dose DOACs (vs. warfarin), respectively. The proportion of patients starting on a low-dose DOAC was higher in women than men. Older age for both sexes and CHADS2 score ≥2 (only women) were major factors of low-dose dabigatran and rivaroxaban versus warfarin use. The only significant factor of standard-dose DOAC versus warfarin use was age of 65-79 for women or men treated with apixaban by 1.8- and 1.4-fold, respectively. Factors that made women and men less likely to receive a standard-dose DOAC versus warfarin were higher CHADS2 (for dabigatran and rivaroxaban), HAS-BLED and frailty scores, prior coronary disease, major bleeding, and chronic kidney disease (CKD) status. The choice of a low- versus standard-dose DOAC was mainly driven by age and CKD, and higher CHADS2 score (for dabigatran and apixaban) for both sexes.

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.

Low Exposure to Direct Oral Anticoagulants Is Associated with Ischemic Stroke and Its Severity

Background and purpose

In acute stroke patients, plasma concentrations of direct oral anticoagulants (DOAC) at hospital admission only poorly mirror DOAC exposure or the coagulation status at the time of the event. Here, we evaluated whether DOAC exposure and DOAC plasma concentration at the time of transient ischemic attacks (TIA) and ischemic strokes correlate with their likelihood of occurrence.

Methods

Prospectively, consecutive DOAC patients with acute ischemic stroke or TIA were included. Admission DOAC plasma concentrations were measured by ultraperformance liquid chromatography– tandem mass spectrometry. Individual DOAC exposure (area under the curve) and DOAC concentrations at event onset were derived from population pharmacokinetic analyses.

Results

DOAC exposure was successfully modeled in 211 patients (ischemic stroke 74.4%, TIA 25.6%). Compared to published values, 63.0% had relatively lower DOAC exposure and they more often received lower DOAC doses than recommended (odds ratio [OR], 2.125; 95% confidence interval [CI], 1.039 to 4.560; P=0.044). These patients more likely suffered ischemic strokes than TIA (OR, 2.411; 95% CI, 1.254 to 4.638; P=0.008) and their strokes were more severe (slope, 3.161; 95% CI, 0.741 to 5.58; P=0.011). Low relative DOAC concentrations at event onset were likewise associated with ischemic strokes (OR, 4.123; 95% CI, 1.834 to 9.268; P=0.001), but not to stroke severity (P=0.272). DOAC exposure had a higher explanatory value for stroke severity than concentrations at event.

Conclusions

Low DOAC exposure is strongly associated to ischemic stroke and its severity. By monitoring DOAC plasma concentrations, patients prone to ischemic stroke might be identified.

Review Article: Gastrointestinal Bleeding Risk with Direct Oral Anticoagulants

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Potential Dexamethasone-Direct Oral Anticoagulant Drug Interaction: Is This a Concern in COVID?

OBJECTIVE

To evaluate the literature on a potential dexamethasone-direct oral anticoagulant (DOAC) drug interaction and provide management considerations with COVID hypercoagulability.

DATA SOURCES

A search of EMBASE, PubMed, and Google Scholar (January 1990 to May 2021), limited to the English language, using applicable search terms resulted in 137 articles, with 21 relevant articles included. Regulatory agency and clinical guidance documents were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

Included articles describe in vitro or in vivo animal or human data for dexamethasone induction of cytochrome P450 (CYP) 3A4 or P-glycoprotein (P-gp).

DATA SYNTHESIS

Dexamethasone has the potential to interact with the DOACs via CYP3A4 and/or P-gp induction. Only apixaban and rivaroxaban have CYP3A4 metabolism. Dexamethasone can increase CYP3A4 activity by up to 70% and reduce the area under the concentration-time curve (AUC) of CYP3A4 substrates by >40%, which is consistent with criteria for a weak CYP inducer. In rodents, dexamethasone P-gp induction is associated with AUC reductions of 20% to 50%. Human data are lacking.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Severe COVID-19 infection is associated with hypercoagulability. Although heparins are the preferred anticoagulants for hospitalized COVID-19 patients, DOACs are being utilized. Dexamethasone is recommended for hospitalized COVID-19 patients requiring supplemental oxygen. The concurrent use of dexamethasone and apixaban or rivaroxaban in such patients carries the potential for reduced anticoagulant effect during a state of heightened thrombotic risk.

CONCLUSIONS

Concurrent use of dexamethasone and apixaban or rivaroxaban in hospitalized COVID-19 patients with laboratory evidence of COVID coagulopathy should be avoided until higher-quality data are available.

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

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

Direct Oral Anticoagulants Versus Vitamin-K Antagonist After PCIs in Patients With AF: A Meta-analysis of Cardiac Ischemic Events

BACKGROUND

Clinical trials have assessed the effect of direct oral antagonists (DOACs) in patients with atrial fibrillation (AF) after percutaneous coronary interventions (PCI). Studies were designed to test the effect on bleeding incidence, but concerns related to safety on ischemic events remain.

METHODS

We performed a meta-analysis with currently available studies involving DOACs versus Vitamin-K antagonist (VKA) in patients with AF after PCI. The primary endpoint was the incidence of cardiac ischemic events, including myocardial infarction and stent thrombosis. Secondary endpoints were the incidence of stroke, all-cause mortality, and major bleeding.

RESULTS

Eleven thousand twenty-three patients were included in the analysis: 5510 receiving DOACs and 5513 VKA. A total of 190 cases of myocardial infarction were registered in patients treated with DOACs and 177 in patients on VKA, and no statistical difference was noted [relative risk (RR): 1.07 95% confidence interval (CI) 0.88-1.31]. The incidence of stent thrombosis was very low with no differences between both treatment strategies (RR: 1.14 95% CI 0.76-1.71). The incidence of cardiac ischemic events was the same in patients receiving DOACs or VKA (HR 1.09 95% CI 0.91-1.30). No differences were observed in the incidence of stroke (RR: 0.86 95% CI 0.61-1.23) or mortality (RR: 1.09, 95% CI 0.90-1.31). Treatment with DOACs was associated with 34% reduction in major bleeding (RR: 0.66, 95% CI 0.54-0.81).

CONCLUSIONS

Treatment with DOACs in patients with AF after a PCI do not increase the risk of cardiac ischemic events, stroke, or death and reduce the incidence of major bleeding by 34% as compared with VKA.

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.

Appropriateness of direct oral anticoagulant dosing in patients with atrial fibrillation according to the drug labelling and the EHRA Practical Guide

BACKGROUND

This study aimed to evaluate the prevalence of potential drug-drug interactions (DDIs) and the appropriateness of direct oral anticoagulant (DOAC) dosing according to both the Summary of Product Characteristics (SmPC) and the European Heart Rhythm Association (EHRA) Practical Guide in a 'real-world' sample of non-valvular atrial fibrillation (NVAF) patients.

METHODS AND RESULTS

Data of a cross-sectional observational study in a primary care sample of 654 long-term DOAC users were used for this sub-analysis. A total of 262 potential DDIs were identified in 220 patients (33.6%). Pharmacodynamic DDIs were present in 163 patients (24.9%) and pharmacokinetic DDIs in 82 patients (12.5%). One-third of patients (33.8%) received reduced DOAC dose. According to the dosing recommendations in the SmPC, 81.7% of DOACs were dosed appropriately. According to the EHRA recommendations, 76.6% of DOACs were dosed appropriately. Dosing recommendations were consistent for 90.7% of patients, with both the SmPC and EHRA Practical Guide considering DOACs dosed appropriately in 74.5% of patients, overdosed in 7.8%, underdosed in 7.6% and contraindicated in 0.8%. However, for the remaining 9.3% dosing recommendations differed between SmPC and EHRA.

CONCLUSIONS

This 'real-world' analysis of DOAC dosing demonstrated that in about one-third of NVAF patients potential DDIs were present. In 18.3% and 23.4% of patients, DOACs were dosed inappropriately according to the SmPC and EHRA Practical Guide respectively. In almost 10% of the study population dosing advice was inconsistent between both references. More research is needed to ensure appropriate DOAC dosing in this 'grey zone' population.

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.