Management strategies of the interaction between direct oral anticoagulant and drug-metabolizing enzyme inducers

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.

Safety and efficacy of concomitant treatment with non-vitamin K antagonist oral anticoagulants and antiseizure medications: A propensity score matching cohort study

Research on cerebrovascular events in atrial fibrillation (AF) patients taking non-vitamin K antagonist oral anticoagulants (NOACs) with antiseizure medications (ASMs) is limited, highlighting a significant gap in literature. We assessed thrombotic and hemorrhagic risks in patients on NOACs and ASMs versus those on NOACs or ASMs alone. We analyzed a retrospective cohort from five centers, including AF and epilepsy patients on both medications (n = 188), AF patients on NOACs (n = 298), and epilepsy patients on ASMs (n = 50), with a 3-year follow-up. Propensity score matching adjusted for cardiovascular risk differences. The primary outcomes were ischemic stroke, transient ischemic attack, and major bleeding. Results showed the ASM+NOAC group had a higher risk of primary outcomes compared to the NOAC-only group (5.68% vs. 1.18%, hazard ratio = 5.72, 95% confidence interval = 2.22-14.73), with no events in the ASM-only group. This suggests an increased risk for patients on combined NOAC and ASM therapy, underlining the need for careful drug interaction consideration.

Direct-Acting Oral Anticoagulants and Antiseizure Medications for Atrial Fibrillation and Epilepsy and Risk of Thromboembolic Events

Importance

Direct-acting oral anticoagulants (DOACs) are commonly prescribed with antiseizure medications (ASMs) due to concurrency of and the association between atrial fibrillation (AF) and epilepsy. However, enzyme-inducing (EI) ASMs may reduce absorption and accelerate metabolism of DOACs, potentially lowering DOAC levels and elevating thromboembolism risk.

Objective

To assess the rates of thromboembolic and major bleeding events in adults with AF and epilepsy dispensed DOACs and EI ASMs vs DOACs with non-EI ASMs.

Design, Setting, and Participants

This active-comparator, new-user cohort study included US health care data from the Clinformatics Data Mart database from October 2010 to September 2021 for a nationally representative population of adults with AF and epilepsy.

Exposure

Evaluations included episodes of contiguous coadministration of DOACs for AF with EI ASMs (exposed) or non-EI ASMs (referent) for epilepsy.

Main Outcomes and Measures

Thromboembolic events (primary outcome) and major bleeding events (secondary outcome) were identified based on a series of validated, diagnosis-based coding algorithms. Data-adaptive, high-dimensional propensity score matching was used to control for observed confounders and proxies for unobserved confounders. Adjusted hazard ratios (AHRs) were estimated using Cox proportional hazards regression models with robust variance estimators to account for clustering within matched pairs.

Results

This study included 14 078 episodes (median age, 74 [IQR, 67-81]; 52.4% female) and 14 158 episodes (median age, 74 [IQR, 67-81]; 52.4% female) of incident DOAC and ASM use that met eligibility criteria for assessment of thromboembolic and major bleeding outcomes, respectively. Incidence was 88.5 per 1000 person-years for thromboembolic events and 68.3 per 1000 person-years for bleeding events. Compared with use of non-EI ASMs, use of EI ASMs with DOACs was not associated with a difference in risk of thromboembolic events (AHR, 1.10; 95% CI, 0.82-1.46) but was associated with a reduction in risk of major bleeding events (AHR, 0.63; 95% CI, 0.44-0.89).

Conclusions and Relevance

In this cohort study, EI ASMs were not associated with alteration in DOAC efficacy. Further research is needed on the reduction in bleeding risk associated with EI ASMs, as this may suggest that pharmacokinetic interactions are associated with lowering DOAC levels without negating therapeutic effects.

Direct Oral Anticoagulants and Concomitant Anti-seizure Medications: A Retrospective, Case-Control Study in a Real-World Setting

PURPOSE

Although prescription of direct oral anticoagulants (DOACs) for epileptic patients on anti-seizure medications (ASMs) is on the increase, international guidelines pose strict restrictions because this may lead to pharmacologic interactions. However, current evidence on their clinical relevance remains scanty. This retrospective, case-control study assessed the frequency of ischemic/hemorrhagic events and epileptic seizures involving DOAC-ASM cotherapy in the real world, compared with DOAC and ASM monotherapy, in age- and gender-matched controls.

METHODS

Data on patients who had been prescribed a concomitant DOAC and ASM therapy for at least 6 months were extracted from the database of the Pharmaceutical Service of the Alessandria Province (Italy). After exclusions, the case group included 124 patients, 44 on valproic acid (VPA) and 80 on levetiracetam (LEV) concomitant with a DOAC, and it was compared with the DOAC-control and ASM-control groups. The clinical and laboratory data were extracted from the electronic archives of the hospitals in the same province.

FINDINGS

Two (1.6%) ischemic and 2 (1.6%) major hemorrhagic events were observed in the case group. Four (3.2%) ischemic and no hemorrhagic events occurred in the DOAC-control group. There were no statistically significant differences in the ischemic and hemorrhagic events between the case group (patients on concomitant LEV or VPA who were prescribed a DOAC) and the DOAC-control group, and there was no difference in the recurrence rate of epileptic seizures between the case group and the ASM-control group.

IMPLICATIONS

Although this study has some limits, mainly the small sample size, our findings indicate that neither LEV nor VPA concomitant treatment significantly affects the effects of DOACs in a real-world setting.

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.

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.

Interactions Between Direct Oral Anticoagulants (DOACs) and Antiseizure Medications: Potential Implications on DOAC Treatment

The use of direct oral anticoagulants (DOACs) is increasing because of their superior efficacy and safety compared with vitamin K antagonists. Pharmacokinetic drug interactions, particularly those involving cytochrome P450- mediated metabolism and P-glycoprotein transport, significantly affect the efficacy and safety of DOACs. In this article, we assess the effects of cytochrome P450- and P-glycoprotein-inducing antiseizure medications on DOAC pharmacokinetics in comparison to rifampicin. Rifampicin decreases to a varying extent the plasma exposure (area under the concentration-time curve) and peak concentration of each DOAC, consistent with its specific absorption and elimination pathways. For apixaban and rivaroxaban, rifampicin had a greater effect on the area under the concentration-time curve than on peak concentration. Therefore, using peak concentration to monitor DOAC concentrations may underestimate the effect of rifampicin on DOAC exposure. Antiseizure medications that are cytochrome P450 and P-glycoprotein inducers are commonly used with DOACs. Several studies have observed a correlation between the concomitant use of DOACs and enzyme-inducing antiseizure medications and DOAC treatment failure, for example, ischemic and thrombotic events. The European Society of Cardiology recommends avoiding this combination, as well as the combination of DOACs with levetiracetam and valproic acid, owing to a risk of low DOAC concentrations. However, levetiracetam and valproic acid are not cytochrome P450 or P-glycoprotein inducers, and the implications of their use with DOACs remain to be elucidated. Our comparative analysis suggests DOAC plasma concentration monitoring as a possible strategy to guide dosing owing to the predictable correlation between DOACs' plasma concentration and effect. Patients taking concomitant enzyme-inducing antiseizure medications are at risk for low DOAC concentrations and subsequently, treatment failure and thus can benefit from DOAC concentration monitoring to prophylactically identify this risk.

Complexity and clinical significance of drug-drug interactions (DDIs) in oncology: challenging issues in the care of patients regarding cancer-associated thrombosis (CAT)

Cancer patients have an increased risk of developing venous thromboembolic events. Anticoagulation management includes prophylactic or therapeutic doses of low molecular weight heparins (LMWHs) or direct oral anticoagulants (DOACs). However, the management of thrombosis in patients with cancer is complex due to various individual and disease-related factors, including drug–drug interactions (DDIs). Furthermore, DDIs may impact both, cancer and venous thrombosis, treatment effectiveness and safety; their relevance is highlighted by the advances in cancer therapeutics. Given that these new oncology drugs are extensively used, more attention should be given to monitoring potential DDIs to minimize risks. Recognition of DDIs is of utmost importance in an era of rapid developments in cancer treatments and introduction of novel treatments and protocols. When managing cancer-associated thrombosis (CAT), the concomitant use of a DOAC and a moderate or strong modulator (inhibitor or inducer) of CYP3A4 or a P-glycoprotein (P-gp) is most likely to be associated with significant DDIs. Therefore, LMWHs remain the first-line option for the long-term management of CAT under these circumstances and physicians must consider utilizing LMWHs as first line. This review describes the risk of DDIs and their potential impact and outcomes in patients with cancer associated thrombosis (CAT) receiving anticoagulation.

The Impact of Strong Inducers on Direct Oral Anticoagulant Levels

PURPOSE

The concomitant use of direct oral anticoagulants (DOAC) and strong P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4) inducers may lead to reduced DOAC levels and therapeutic failure. This study aimed to describe DOAC concentrations in patients receiving strong P-gp and CYP3A4 inducers, in relation to individual risk factors for high or low DOAC levels.

METHODS

We retrospectively identified hospitalized patients simultaneously receiving a DOAC and carbamazepine, phenobarbital, phenytoin, or rifampicin between 2016 and 2021. Among them, patients who underwent DOAC measurement at steady state were included. DOAC peak or trough levels were compared with on-therapy ranges observed in pivotal trials. Individual risk factors for high or low DOAC levels were identified.

RESULTS

We included 17 patients (median age 75 years), mainly receiving apixaban and carbamazepine. For 5 patients (29%), DOAC trough or peak level was below the expected range. Among the remaining 12 patients, 8 had at least one measurement in the lower quartile of the range. The median number of risk factors for drug accumulation was 0 (range 0-1) in patients with ≥1 measurement below the range and 2 (range 0-3) in other patients. DOAC measurement led to treatment adjustments in 9 patients (DOAC dose increase or switch).

CONCLUSION

Our data suggest a significant risk of reduced DOAC levels in patients taking strong P-gp and CYP3A4 inducers, especially those without risk factors for drug accumulation. DOAC measurement could help manage this relevant drug-drug interaction.

Analysis of Direct Oral Anticoagulant Therapy With Concomitant Use of Interacting Antiretroviral Agents

Background: A theoretical interaction exists between human immunodeficiency virus (HIV) antiretroviral (ARV) agents and direct oral anticoagulants (DOACs), although the clinical significance is unclear. Objective: This study aimed to assess characteristics, prescribing patterns, and outcomes associated with concomitant therapy. Methods: A single-center, retrospective review was performed on patients older than 18 years prescribed a DOAC for any indication with concurrent interacting ARV(s) from June 2016 through June 2019. The primary endpoint was to assess prescribing and population characteristics. Secondary endpoints were to evaluate safety outcomes, DOAC level monitoring, readmissions, outpatient follow-up, and DOAC modification interventions. Results: Thirty-six patients (72 hospital admissions) were identified. The most common DOAC was apixaban (83.3%) and ARV was ritonavir (50%). Of the 72 encounters, 26 (36.1%) DOACs were dosed appropriately per guideline recommendations. Twenty pharmacy interventions for therapy modification were recognized. Eleven (30.6%) patients experienced bleeding and 2 (5.6%) thrombosis. Of the adverse events, all patients had renal impairment. Conclusions: As DOAC utilization grows, increasing use in HIV could be expected. More frequent adjustment or avoidance is recommended per guidelines. Our data suggest the majority of patients receive CYP3A4-inhibiting regimens. Caution should be employed with renal insufficiencies. Further studies are warranted to assess safety and efficacy within this population.

Effect of Enzyme-Inducing Antiseizure Medications on the Risk of Sub-Therapeutic Concentrations of Direct Oral Anticoagulants: A Retrospective Cohort Study

BACKGROUND

Stroke and thromboembolic events occurring among patients taking direct oral anticoagulants (DOACs) have been associated with low concentrations of DOACs. Enzyme-inducing antiseizure medications (EI-ASMs) are associated with enhanced cytochrome-P450-mediated metabolism and enhanced P-glycoprotein-mediated transport.

OBJECTIVE

The aim of this study was to evaluate the effect of concomitant EI-ASM use on DOAC peak concentrations in patients treated in clinical care.

METHODS

We performed a retrospective cohort study of patients treated with DOACs for atrial fibrillation and venous thromboembolic disease in an academic general hospital. In total, 307 patients treated with DOACs between August 2015 and January 2020 were reviewed. Clinical characteristics and peak DOAC plasma concentrations of patients co-treated with an EI-ASM were compared with those of patients not treated with an EI-ASM. An apixaban dose score (ADS) was defined to account for apixaban dosage and the number of apixaban dose-reduction criteria.

RESULTS

In total, 177 peak DOAC plasma concentrations (including apixaban, rivaroxaban, and dabigatran) from 131 patients were measured, including 24 patients co-treated with an EI-ASM and 107 controls not treated with an EI-ASM. The proportion of patients with DOAC concentrations below the expected range was significantly higher among EI-ASM users than among patients not taking an EI-ASM (37.5 vs. 9.3%, respectively; p = 0.0004; odds ratio 5.82; 95% confidence interval [CI] 2.03-16.66). Most of these patients were treated with apixaban (85%); however, sensitivity analysis results were also significant (p = 0.031) for patients with non-apixaban DOACs. In patients co-treated with apixaban and an EI-ASM, median apixaban peak concentration was 106 ng/mL (interquartile range [IQR] 71-181) compared with 150 ng/mL (IQR 94-222) in controls (p = 0.019). In multivariable analysis, EI-ASM use was associated with 6.26-fold increased odds for apixaban concentration below the expected range (95% CI 2.19-17.90; p = 0.001). Apixaban concentrations were significantly associated with EI-ASM use, moderate enzyme inhibitor use, and ADS.

CONCLUSIONS

Concurrent EI-ASM and DOAC use presents a possible risk for DOAC concentrations below the expected range. The clinical significance of the interaction is currently unclear.

Concomitant Use of Direct Oral Anticoagulants and Antiepileptic Drugs: A Prospective Cohort Study in Patients with Atrial Fibrillation

BACKGROUND

European guidelines do not recommend the use of carbamazepine, levetiracetam, phenobarbital, phenytoin, topiramate and valproic acid in patients taking direct oral anticoagulants (DOACs). Little is known regarding the clinical relevance of the interaction between DOACs and antiepileptic drugs.

OBJECTIVES

To evaluate the incidence of thromboembolic and bleeding events in patients with non-valvular atrial fibrillation (AF) concurrently treated with DOACs and antiepileptic drugs.

METHODS

This is a prospective multicentre cohort study of patients with non-valvular AF concurrently treated with DOACs and antiepileptic drugs. The primary outcome was ischaemic stroke/transient ischaemic attack (TIA)/systemic embolism (SE). Secondary outcome was major bleeding (MB). Incidence rates (% patient-year) were evaluated for the study outcomes.

RESULTS

Overall, 91 patients were included. Mean age was 78 ± 9.5 years, 49.5% were female. Mean CHA₂DS₂-VASc score was 4.76 ± 1.59 and mean HAS-BLED was 2.67 ± 1.26. Overall, 41, 20, 11, 10 and 9 out of 91 patients were treated with levetiracetam, valproic acid, phenobarbital, carbamazepine and other antiepileptic drugs, respectively. During a median follow-up of 17.5 ± 14.5 months, stroke/TIA/SE occurred in 9 patients (5.7% patient-year) and MB in 3 patients (1.9% patient-year). Ischaemic stroke was fatal in 3 patients (1.9% patient-year) and MB in one patient (0.6% patient-year).

CONCLUSION

In this cohort, patients with non-valvular AF treated with DOACs and antiepileptic drugs appear to have a relatively high rate of thromboembolic events.

Effects of Hypericum perforatum (St John's wort) on the pharmacokinetics and pharmacodynamics of rivaroxaban in humans

AIMS

To investigate the influence of a cytochrome P450 CYP3A4 and efflux transporter P-glycoprotein (P-gp) inducing Hypericum perforatum extract on the pharmacokinetics and pharmacodynamics of rivaroxaban.

METHODS

Open-label, nonrandomized, sequential treatment interaction study. Following CYP3A4 and P-gp phenotyping using low-dose midazolam and fexofenadine, 12 healthy volunteers received a single oral dose of 20 mg rivaroxaban and rivaroxaban plasma concentrations and inhibition of the activated coagulation factor X (factor Xa) activity were measured prior to and up to 48 h postdosing. The procedures were repeated after 2 weeks' treatment with the H. perforatum extract.

RESULTS

The geometric mean ratios for the area under the concentration-time curve and C_max of rivaroxaban after/before induction with the H. perforatum extract were 0.76 (90% confidence interval [CI] 0.70, 0.82) and 0.86 (90% CI 0.76, 0.97), respectively. Inhibition of factor Xa activity was reduced with a geometric mean area under the effect-time curve ratio after/before induction of 0.80 (90% CI 0.71, 0.89). No clinically significant differences were found regarding T_max (median 1.5 vs 1 h, P = .26) and terminal elimination half-life (mean 10.6 vs 10.8 h, P = .93) of rivaroxaban. The H. perforatum extract significantly induced CYP3A4 and P-gp activity, as evidenced by phenotyping.

CONCLUSION

The CYP3A4/P-gp inducing H. perforatum extract caused a decrease of rivaroxaban exposure with a proportional decrease of the pharmacodynamic effect. Although the data do not justify a contraindication for the combination or a systematic adjustment of rivaroxaban dosage, avoidance of the combination or laboratory monitoring should be considered in patients taking hyperforin-containing H. perforatum extracts with rivaroxaban.

Ischemic and Thrombotic Events Associated with Concomitant Xa-inhibiting Direct Oral Anticoagulants and Antiepileptic Drugs: Analysis of the FDA Adverse Event Reporting System (FAERS)

INTRODUCTION

Factor Xa-inhibiting direct oral anticoagulants (FXa-DOACs) undergo hepatic metabolism via cytochrome P-450 (CYP450). Concomitant use of rifampicin, an inducer of these enzymes, with FXa-DOACs, has been shown to decrease FXa-DOAC concentrations in healthy subjects. Several common antiepileptic drugs (AEDs) are known to induce CYP450 enzymes as well. However, little is known regarding the impact of this potential interaction on treatment outcomes with FXa-DOACs.

METHODS

We analyzed adverse event cases submitted to the Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) from January 2013 to December 2018. We compared the proportion of cases reporting thromboembolic and ischemic adverse events (TAIAEs) with the concomitant use of FXa-DOACs and enzyme-inducing AEDs to the proportion of cases with FXa-DOACs and other AEDs.

RESULTS

During this period, 9693 adverse event cases reported concomitant use of FXa-DOACs and AEDs. Almost all reports (> 99%) involved the use of rivaroxaban or apixaban. Compared with other AEDs, enzyme-inducing AEDs were associated with an 86% increase in the odds of reporting TAIAEs [reporting odds ratio (ROR) 1.86, 95% confidence interval (CI) 1.61-2.15; p < 0.0001]. In secondary separate analyses of rivaroxaban and apixaban, enzyme-inducing AEDs were similarly associated with increased reporting of a TAIAE (ROR 1.79, 95% CI 1.50-2.12, and ROR 1.88, 95% CI 1.41-2.48, respectively).

CONCLUSION

Using real world data, we observed an increase in the odds of reporting anticoagulation treatment failure among patients treated with FXa-DOACs and concomitant enzyme-inducing AEDs compared to those treated with other AEDs.