Rivaroxaban With and Without Amiodarone in Renal Impairment

Combination of Rivaroxaban and Amiodarone Increases Bleeding in Patients With Atrial Fibrillation

BACKGROUND

Rivaroxaban and amiodarone are commonly used for treating patients with atrial fibrillation. Drug-drug interactions between rivaroxaban and amiodarone may increase exposure to rivaroxaban. However, the clinical relevance of this drug-drug interaction is still not clear.

OBJECTIVE

The aim was to investigate the risk of bleeding in patients receiving a combination of rivaroxaban and amiodarone.

METHODS

This was a prospective observational study in which we included atrial fibrillation patients treated with rivaroxaban. The patients were divided into the rivaroxaban group and the combination of rivaroxaban and amiodarone group (the combination group). Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were performed to adjust between-group differences. The primary endpoint was defined as the time to the first occurrence of a composite of major, clinically relevant nonmajor, and minor bleeding.

RESULTS

In total, 481 atrial fibrillation patients were included in the analysis. After PSM, 154 patients in the rivaroxaban group were matched with 154 patients in the combination group. The bleeding events mainly consisted of clinically relevant nonmajor and minor bleeding. Only one patient experienced major bleeding. The primary outcome was recorded in 26.0% of patients in the combination group and 10.4% of patients in the rivaroxaban group (hazard ratio = 2.76, 95% CI = 1.55-4.93, P < 0.001). The bleeding risk was significantly higher in the combination group compared with that in the rivaroxaban group in the IPTW and stabilized IPTW analyses (hazard ratio = 2.17, 95% CI = 1.32-3.56, P = 0.002).

CONCLUSION AND RELEVANCE

The combination of rivaroxaban and amiodarone increased the risk of bleeding in patients with atrial fibrillation, especially clinically relevant nonmajor and minor bleeding. Physicians prescribing rivaroxaban and amiodarone together should be concerned about an increase in the risk of nonmajor bleeding.

Co-Administration of Amiodarone Increases Bleeding by Affecting Rivaroxaban Pharmacokinetics in Patients with Atrial Fibrillation

This study aimed to investigate the impact of the drug-drug interaction between rivaroxaban and amiodarone on the clinical outcomes in patients with non-valvular atrial fibrillation (NVAF), focusing on pharmacokinetic and pharmacodynamic (PK/PD) aspects. A prospective study enrolling 174 patients with NVAF who were treated with rivaroxaban was conducted. The patients were divided into two groups based on postoperative antiarrhythmic and anticoagulation strategies: the rivaroxaban group (Control group) and the rivaroxaban plus amiodarone group (Riv/Amio group). The trough plasma concentrations (Ctrough) of rivaroxaban, activated partial thromboplastin time (APTT), prothrombin time (PT), and the clinical outcomes between the two groups were compared. Patients receiving 20 mg of rivaroxaban in the Riv/Amio group had a higher concentration of rivaroxaban Ctrough than those in the Control group (p = 0.009). Furthermore, in patients with moderate to severe renal impairment, rivaroxaban Ctrough was significantly increased in the Riv/Amio group. There was no significant difference in PT and APTT between the two groups. Regarding the clinical outcomes, the combination of rivaroxaban and amiodarone medication was associated with a higher incidence of bleeding events (p = 0.041; HR = 2.83, 95% CI 1.05-7.66) and clinically relevant non-major bleeding (p = 0.021; HR = 3.65, 95% CI 1.21-10.94). Finally, independent risk factors for bleeding in NAVF patients treated with rivaroxaban were identified as its combination with amiodarone (p = 0.044; OR = 2.871, 95% CI 1.028-8.023). The combination of rivaroxaban and amiodarone led to changes in rivaroxaban pharmacokinetics and an elevated risk of bleeding events. Therefore, physicians prescribing rivaroxaban medications should assess the potential bleeding risk associated with the concurrent use of amiodarone, particularly in patients with renal impairment.

Recent Progress on Physiologically Based Pharmacokinetic (PBPK) Model: A Review Based on Bibliometrics

Physiologically based pharmacokinetic/toxicokinetic (PBPK/PBTK) models are designed to elucidate the mechanism of chemical compound action in organisms based on the physiological, biochemical, anatomical, and thermodynamic properties of organisms. After nearly a century of research and practice, good results have been achieved in the fields of medicine, environmental science, and ecology. However, there is currently a lack of a more systematic review of progress in the main research directions of PBPK models, especially a more comprehensive understanding of the application in aquatic environmental research. In this review, a total of 3974 articles related to PBPK models from 1996 to 24 March 2024 were collected. Then, the main research areas of the PBPK model were categorized based on the keyword co-occurrence maps and cluster maps obtained by CiteSpace. The results showed that research related to medicine is the main application area of PBPK. Four major research directions included in the medical field were "drug assessment", "cross-species prediction", "drug-drug interactions", and "pediatrics and pregnancy drug development", in which "drug assessment" accounted for 55% of the total publication volume. In addition, bibliometric analyses indicated a rapid growth trend in the application in the field of environmental research, especially in predicting the residual levels in organisms and revealing the relationship between internal and external exposure. Despite facing the limitation of insufficient species-specific parameters, the PBPK model is still an effective tool for improving the understanding of chemical-biological effectiveness and will provide a theoretical basis for accurately assessing potential risks to ecosystems and human health. The combination with the quantitative structure-activity relationship model, Bayesian method, and machine learning technology are potential solutions to the previous research gaps.

Risk for Bleeding-Related Hospitalizations During Use of Amiodarone With Apixaban or Rivaroxaban in Patients With Atrial Fibrillation : A Retrospective Cohort Study

BACKGROUND

Amiodarone, the most effective antiarrhythmic drug in atrial fibrillation, inhibits apixaban and rivaroxaban elimination, thus possibly increasing anticoagulant-related risk for bleeding.

OBJECTIVE

For patients receiving apixaban or rivaroxaban, to compare risk for bleeding-related hospitalizations during treatment with amiodarone versus flecainide or sotalol, antiarrhythmic drugs that do not inhibit these anticoagulants' elimination.

DESIGN

Retrospective cohort study.

SETTING

U.S. Medicare beneficiaries aged 65 years or older.

PATIENTS

Patients with atrial fibrillation began anticoagulant use between 1 January 2012 and 30 November 2018 and subsequently initiated treatment with study antiarrhythmic drugs.

MEASUREMENTS

Time to event for bleeding-related hospitalizations (primary outcome) and ischemic stroke, systemic embolism, and death with or without recent (past 30 days) evidence of bleeding (secondary outcomes), adjusted with propensity score overlap weighting.

RESULTS

There were 91 590 patients (mean age, 76.3 years; 52.5% female) initiating use of study anticoagulants and antiarrhythmic drugs, 54 977 with amiodarone and 36 613 with flecainide or sotalol. Risk for bleeding-related hospitalizations increased with amiodarone use (rate difference [RD], 17.5 events [95% CI, 12.0 to 23.0 events] per 1000 person-years; hazard ratio [HR], 1.44 [CI, 1.27 to 1.63]). Incidence of ischemic stroke or systemic embolism did not increase (RD, -2.1 events [CI, -4.7 to 0.4 events] per 1000 person-years; HR, 0.80 [CI, 0.62 to 1.03]). The risk for death with recent evidence of bleeding (RD, 9.1 events [CI, 5.8 to 12.3 events] per 1000 person-years; HR, 1.66 [CI, 1.35 to 2.03]) was greater than that for other deaths (RD, 5.6 events [CI, 0.5 to 10.6 events] per 1000 person-years; HR, 1.15 [CI, 1.00 to 1.31]) (HR comparison: P = 0.003). The increased incidence of bleeding-related hospitalizations for rivaroxaban (RD, 28.0 events [CI, 18.4 to 37.6 events] per 1000 person-years) was greater than that for apixaban (RD, 9.1 events [CI, 2.8 to 15.3 events] per 1000 person-years) (P = 0.001).

LIMITATION

Possible residual confounding.

CONCLUSION

In this retrospective cohort study, patients aged 65 years or older with atrial fibrillation treated with amiodarone during apixaban or rivaroxaban use had greater risk for bleeding-related hospitalizations than those treated with flecainide or sotalol.

PRIMARY FUNDING SOURCE

National Heart, Lung, and Blood Institute.

Prevalence and bleeding risk associated with the concomitant use of direct oral anticoagulants and antiarrhythmic drugs in patients with atrial fibrillation, based on the French healthcare insurance database

PURPOSE

Pharmacokinetic interactions exist between apixaban or rivaroxaban, and CYP3A4 and P-glycoprotein inhibitors such as amiodarone, verapamil and diltiazem. We aimed to estimate the prevalence of exposure to this drug-drug association (DDA) and to assess the bleeding risk associated in patients with atrial fibrillation (AF).

METHODS

We conducted a cohort study using a representative 1/97^th sample of the French healthcare insurance database between 2014 and 2019. Patients with AF receiving apixaban or rivaroxaban were included and followed-up until hospitalization for bleeding, death, discontinuation of apixaban or rivaroxaban, exposure to strong CYP3A4 inhibitor, or until December 31^st 2019, whichever came first. Primary outcome was hospitalization for bleeding registered as primary diagnosis. The association between the exposure to the DDA and hospitalization for bleeding was evaluated as a time-dependent variable in Cox model.

RESULTS

Between 2014 and 2019, the AF population under apixaban or rivaroxaban represented 10,392 patients. During the study period, the annual average prevalence of DDA exposure in this population was 38.9%. Among the 10,392 patients, 223 (2.1%) were hospitalized for bleeding, of which 75 (33.6%) received the association and 148 (66.4%) received apixaban or rivaroxaban alone. There was no association between DDA exposure and risk of hospitalization for bleeding (aHR = 1.19, [95% CI: 0.90, 1.58]). Age (HR 1.03 [1.02, 1.05]) and male gender (HR 1.72 [1.28, 2.30]) were associated with an increased risk of hospitalization for bleeding.

CONCLUSION

Exposure to antiarrhythmic drugs was not associated with an increased risk of hospitalization for bleeding in patients with AF under rivaroxaban or apixaban.

Impact of amiodarone on plasma concentration of direct oral anticoagulant in patients with atrial fibrillation

BACKGROUND/PURPOSE

Amiodarone increases exposure of direct oral anticoagulants (DOACs). We aimed to analyze the effects of concurrent amiodarone use on DOAC concentrations and clinical outcomes.

METHODS

Patients who were ≥20 years of age, had atrial fibrillation, and took DOAC were enrolled to provide trough and peak samples for DOAC concentration measurements using ultra-high-performance liquid chromatography-tandem mass spectrometry. The results were compared with concentrations reported in clinical trials to define above, within, or under the expected range. The outcomes of interest were major bleeding and any gastrointestinal bleeding. Multivariate logistic regression and Cox proportional hazards model were used to determine the impact of amiodarone on above-range concentration and clinical outcomes, respectively.

RESULTS

A total of 722 participants (420 men, 58.2%) were enrolled to provide 691 trough samples and 689 peak samples. Among them, 21.3% concurrently used amiodarone. The proportion of patients with above-range trough and peak concentrations was 16.4% and 30.2%, respectively, for amiodarone users, in contrast to 9.4% and 19.8% for amiodarone non-users. The use of amiodarone was associated with above-range trough and peak concentrations (odds ratio [OR] = 2.00 [1.16, 3.47] and 1.82 [1.19, 2.79], respectively). However, amiodarone was not a significant predictor of major bleeding or any gastrointestinal bleeding.

CONCLUSION

Concurrent amiodarone use led to increased DOAC concentration but was not associated with a higher risk of major bleeding or any gastrointestinal bleeding. Therapeutic monitoring of DOAC users concurrently taking amiodarone may be recommended for patients with an additional risk of increased DOAC exposure.

Personalizing Direct Oral Anticoagulant Therapy for a Diverse Population: Role of Race, Kidney Function, Drug Interactions, and Pharmacogenetics

Oral anticoagulants (OACs) are commonly used to reduce the risk of venous thromboembolism and the risk of stroke in patients with atrial fibrillation. Endorsed by the American Heart Association, American College of Cardiology, and the European Society of Cardiology, direct oral anticoagulants (DOACs) have displaced warfarin as the OAC of choice for both conditions, due to improved safety profiles, fewer drug-drug and drug-diet interactions, and lack of monitoring requirements. Despite their widespread use and improved safety over warfarin, DOAC-related bleeding remains a major concern for patients. DOACs have stable pharmacokinetics and pharmacodynamics; however, variability in DOAC response is common and may be attributed to numerous factors, including patient-specific factors, concomitant medications, comorbid conditions, and genetics. Although DOAC randomized controlled trials included patients of varying ages and levels of kidney function, they failed to include patients of diverse ancestries. Additionally, current evidence to support DOAC pharmacogenetic associations have primarily been derived from European and Asian individuals. Given differences in genotype frequencies and disease burden among patients of different biogeographic groups, future research must engage diverse populations to assess and quantify the impact of predictors on DOAC response. Current under-representation of patients from diverse racial groups does not allow for proper generalization of the influence of clinical and genetic factors in relation to DOAC variability. Herein, we discuss factors affecting DOAC response, such as age, sex, weight, kidney function, drug interactions, and pharmacogenetics, while offering a new perspective on the need for further research including frequently excluded groups.

Development and verification of a physiologically based pharmacokinetic model of dronedarone and its active metabolite N-desbutyldronedarone: Application to prospective simulation of complex drug-drug interaction with rivaroxaban

AIMS

Despite potential enzyme- and transporter-mediated drug-drug interactions (DDIs) between dronedarone and rivaroxaban in atrial fibrillation (AF) patients, pharmacokinetic/pharmacodynamic data remain limited to guide clinical practice. We aimed to develop, verify and validate a physiologically based pharmacokinetic (PBPK) model of dronedarone and its major metabolite, N-desbutyldronedarone (NDBD), to prospectively interrogate this clinically relevant DDI in healthy and mild renal impairment populations.

METHODS

The middle-out development of our PBPK model combined literature-derived or in-house in vitro data, predicted in silico data and in vivo clinical data. Model verification was performed for intravenous and oral (single and multiple) dosing regimens. Model validation for the accurate prediction of cytochrome P450 (CYP)3A4- and P-glycoprotein-mediated DDI utilized simvastatin and digoxin as respective victim drugs. Rivaroxaban-specific inhibitory parameters of dronedarone and/or NDBD against CYP3A4, CYP2J2, OAT3 and P-glycoprotein were incorporated into the PBPK-DDI model for prospective dronedarone-rivaroxaban DDI simulation.

RESULTS

Dronedarone and NDBD PK following clinically relevant doses of 400 mg dronedarone across single and multiple oral dosing were accurately simulated by incorporating effect of auto-inactivation on dose nonlinearities. Following successful model validation, nondose-adjusted rivaroxaban-dronedarone DDI in healthy and mild renal impairment populations revealed simulated rivaroxaban area under the plasma concentration-time curve up to 24 h fold change greater than dose exposure equivalence (0.70-1.43) at 1.65 and 1.84, respectively. Correspondingly, respective major bleeding risk was 4.24 and 4.70% compared with threshold of 4.5% representing contraindicated rivaroxaban-ketoconazole DDI.

CONCLUSION

Our PBPK-DDI model predicted clinically significant dronedarone-rivaroxaban DDI in both healthy and mild renal impairment subjects. Greater benefit vs. risk could be achieved with rivaroxaban dose reductions to at least 15 mg in mild renal impairment subjects on concomitant dronedarone and rivaroxaban.

Selection of Specific Aptamer against Rivaroxaban and Utilization for Label-Free Electrochemical Aptasensing Using Gold Nanoparticles: First Announcement and Application for Clinical Sample Analysis

For the first time, a novel aptamer was designed and utilized for the selective detection of rivaroxaban (RIV) using the integration of bioinformatics with biosensing technology. The selected aptamer with the sequence 5'-TAG GGA AGA GAA GGA CAT ATG ATG ACT CAC AAC TGG ACG AAC GTA CTT ATC CCC CCC AAT CAC TAG TGA ATT-3' displayed a high binding affinity to RIV and had an efficient ability to discriminate RIV from similar molecular structures. A novel label-free electrochemical aptasensor was designed and fabricated through the conjugation of a thiolated aptamer with Au nanoparticles (Au-NPs). Then, the aptasensor was successfully applied for the quantitative determination of RIV in human plasma and exhaled breath condensate (EBC) samples with limits of detection (LODs) of 14.08 and 6.03 nM, respectively. These valuable results provide ample evidence of the green electrogeneration of AuNPs on the surface of electrodes and their interaction with loaded aptamers (based on Au-S binding) towards the sensitive and selective monitoring of RIV in human plasma and EBC samples. This bio-assay is an alternative approach for the clinical analysis of RIV and has improved specificity and affinity. As far as we know, this is the first time that an electrochemical aptasensor has been verified for the recognition of RIV and that allows for the easy, fast, and precise screening of RIV in biological samples.

Predicting drug-drug interactions with physiologically based pharmacokinetic/pharmacodynamic modelling and optimal dosing of apixaban and rivaroxaban with dronedarone co-administration

BACKGROUND

The concurrent administration of dronedarone and oral anti-coagulants is common because both are used in managing atrial fibrillation (AF). Dronedarone is a moderate inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme and P-glycoprotein (P-gp). Apixaban and rivaroxaban are P-gp and CYP3A4 substrates. This study aims to investigate the impact of exposure and bleeding risk of apixaban or rivaroxaban when co-administered with dronedarone using physiologically based pharmacokinetic/pharmacodynamic analysis.

METHODS

Modeling and simulation were conducted using Simcyp® Simulator. The parameters required for dronedarone modeling were collected from the literature. The developed dronedarone physiologically based pharmacokinetic (PBPK) model was verified using reported drug-drug interactions (DDIs) between dronedarone and CYP3A4 and P-gp substrates. The model was applied to evaluate the DDI potential of dronedarone on the exposure of apixaban 5 mg every 12 h or rivaroxaban 20 mg every 24 h in geriatric and renally impaired populations. DDIs precipitating major bleeding risks were assessed using exposure-response analyses derived from literature.

RESULTS

The model accurately described the pharmacokinetics of orally administered dronedarone in healthy subjects and accurately predicted DDIs between dronedarone and four CYP3A4 and P-gp substrates with fold errors <1.5. Dronedarone co-administration led to a 1.29 (90 % confidence interval (CI): 1.14-1.50) to 1.31 (90 % CI: 1.12-1.46)-fold increase in the area under concentration-time curve for rivaroxaban and 1.33 (90 % CI: 1.15-1.68) to 1.46 (90 % CI: 1.24-1.92)-fold increase for apixaban. The PD model indicated that dronedarone co-administration might potentiate the mean major bleeding risk of apixaban with a 1.45 to 1.95-fold increase. However, the mean major bleeding risk of rivaroxaban was increased by <1.5-fold in patients with normal or impaired renal function.

CONCLUSIONS

Dronedarone co-administration increased the exposure of rivaroxaban and apixaban and might potentiate major bleeding risks. Reduced apixaban and rivaroxaban dosing regimens are recommended when dronedarone is co-administered to patients with AF.

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.

Drug Interactions Affecting Antiarrhythmic Drug Use

Antiarrhythmic drugs (AAD) play an important role in the management of arrhythmias. Drug interactions involving AAD are common in clinical practice. As AADs have a narrow therapeutic window, both pharmacokinetic as well as pharmacodynamic interactions involving AAD can result in serious adverse drug reactions ranging from arrhythmia recurrence, failure of device-based therapy, and heart failure, to death. Pharmacokinetic drug interactions frequently involve the inhibition of key metabolic pathways, resulting in accumulation of a substrate drug. Additionally, over the past 2 decades, the P-gp (permeability glycoprotein) has been increasingly cited as a significant source of drug interactions. Pharmacodynamic drug interactions involving AADs commonly involve additive QT prolongation. Amiodarone, quinidine, and dofetilide are AADs with numerous and clinically significant drug interactions. Recent studies have also demonstrated increased morbidity and mortality with the use of digoxin and other AAD which interact with P-gp. QT prolongation is an important pharmacodynamic interaction involving mainly Vaughan-Williams class III AAD as many commonly used drug classes, such as macrolide antibiotics, fluoroquinolone antibiotics, antipsychotics, and antiemetics prolong the QT interval. Whenever possible, serious drug-drug interactions involving AAD should be avoided. If unavoidable, patients will require closer monitoring and the concomitant use of interacting agents should be minimized. Increasing awareness of drug interactions among clinicians will significantly improve patient safety for patients with arrhythmias.

Physiologically-Based Pharmacokinetic Modelling to Investigate Baricitinib and Tofacitinib Dosing Recommendations for COVID-19 in Geriatrics

Janus kinase (JAK) inhibitors baricitinib and tofacitinib are recommended by the US National Institutes of Health as immunomodulatory drugs for coronavirus disease 2019 (COVID-19) treatment. In addition, baricitinib has recently received Emergency Use Authorization from the US Food and Drug Administration, although the instruction provided dosing information only for adults. Geriatrics with organ dysfunction are one of the most vulnerable cohorts when combating the pandemic. The aim of the present work was to evaluate current dosing strategies of baricitinib and tofacitinib for potential COVID-19 treatment for White and Chinese geriatric patients with chronic renal impairment. An established physiologically-based pharmacokinetic (PBPK) modeling framework for age-dependent simulations was utilized. PBPK drug models adopted from literature were first verified. Several population models representing different age groups, ethnicities, and stages of renal impairment were used for prospective simulations. Notwithstanding the increase in systemic exposure of both drugs resulting from renal dysfunction was more pronounced for geriatrics than general White populations, our simulations confirmed their current dosage adjustments based on renal functions are broadly adequate. The exception being White older subjects with mild renal impairment where current recommendation of 4 mg baricitinib yielded a 2.31-fold increase in systemic exposure, and reduction to 2 mg could mitigate the potential risk to an acceptable 1.15-fold. Comparable relationships between systemic exposure and renal dysfunction were observed for both drugs in the Chinese population. In summary, PBPK modeling of both JAK inhibitors supports the rational and prudent dose adjustments of these COVID-19 therapeutics among adult patients of different age groups and renal functions.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Model-Based Risk Prediction of Rivaroxaban with Amiodarone for Moderate Renal Impaired Elderly Population

PURPOSE

Increased bleeding risk was found associated with concurrent prescription of rivaroxaban and amiodarone. We previously recommended dose adjustment for rivaroxaban utilizing a physiologically based pharmacokinetic (PBPK) modeling approach. Our subsequent in vitro studies discovered the pivotal involvement of human renal organic anion transporter 3 (hOAT3) in the renal secretion of rivaroxaban and the inhibitory potency of amiodarone. This study aimed to redefine the disease-drug-drug interactions (DDDI) between rivaroxaban and amiodarone and update the potential risks.

METHODS

Prospective simulations were conducted with updated PBPK models of rivaroxaban and amiodarone incorporating hOAT3-related parameters.

RESULTS

Simulations to recapitulate previously explored DDDI in renal impairment showed a higher bleeding tendency in all simulation scenarios after integrating hOAT3-mediated clearance into PBPK models. Further sensitivity analysis revealed that both hOAT3 dysfunction and age could affect the extent of DDDI, and age was shown to have a more pivotal role on rivaroxaban in vivo exposure. When amiodarone was prescribed along with our recommended dose reduction of rivaroxaban to 10 mg in moderate renal impaired elderly people, it could result in persistently higher rivaroxaban peak concentrations at a steady state. To better manage the increased bleeding risk among such a vulnerable population, a dose reduction of rivaroxaban to 2.5 mg twice daily resulted in its acceptable in vivo exposure.

CONCLUSION

Close monitoring of bleeding tendency is essential for elderly patients with moderate renal impairment receiving co-prescribed rivaroxaban and amiodarone. Further dose reduction is recommended for rivaroxaban to mitigate this specific DDDI risk.

Drug-Drug Interactions Leading to Adverse Drug Reactions with Rivaroxaban: A Systematic Review of the Literature and Analysis of VigiBase

Rivaroxaban has become an alternative to vitamin K antagonists, which are considered to be at higher risk of drug-drug interactions (DDI) and more difficult to use. However, DDI do occur. We systematically reviewed studies that evaluated them and analysed DDI and subsequent adverse drug reactions (ADR) reported in spontaneous reports and VigiBase. We systematically searched articles that explored DDI with rivaroxaban up to 20 August 2018 via Medline, Embase and Google Scholar. Data from VigiBase came from spontaneous reports recovered up to 2 January 2018, where Omega was used to detect signals and identify potential interactions in terms of triplets with two drugs and one ADR. We identified 31 studies and 28 case reports. Studies showed significant variation in the pharmacokinetic for rivaroxaban, and an increased risk of haemorrhage or thromboembolic events due to DDI was highlighted in case reports. From VigiBase, a total of 21,261 triplets were analysed and the most reported was rivaroxaban–aspirin–gastrointestinal haemorrhage. In VigiBase, only 34.8% of the DDI reported were described or understood, and most were pharmacodynamic DDI. These data suggest that rivaroxaban should be considered to have significant potential for DDI, especially with CYP3A/P-gp modulators or with drugs that impair haemostasis.

The real world use of combined P-glycoprotein and moderate CYP3A4 inhibitors with rivaroxaban or apixaban increases bleeding

The use of direct oral anticoagulants for stroke prevention in atrial fibrillation continues to rise. Certain populations may be at higher risk for increased drug exposure and adverse events. Pharmacokinetic studies suggest increased exposure of rivaroxaban and apixaban with combined P-gp and moderate CYP3A4 inhibitors but the clinical relevance of this is unknown. This retrospective cohort study included patients receiving rivaroxaban or apixaban from January 1, 2012 to December 31, 2016 with a moderate inhibitor (amiodarone, dronedarone, diltiazem, verapamil) for at least 3 months in the drug-drug interaction (DDI) group. Propensity matching was used to identify similar control patients without the presence of the DDI. The primary outcome was a time to event analysis of any bleeding episode as defined by the International Society of Thrombosis and Hemostasis. After propensity matching, 213 patients with similar baseline characteristics were included in each group. The mean CHA2DS2-VASc score was 3.0 and median duration of follow-up was 1.45 years. The primary outcome occurred in 26.4% of patients in the DDI group and 18.4% in the control group (hazard ratio 1.8, 95% confidence interval [CI] 1.19 to 2.73; p-value = 0.006). There was no difference in bleeding rates based on type of inhibitor. Use of a combined P-gp and moderate CYP3A4 inhibitor with rivaroxaban or apixaban increased bleeding risk compared to patients without the DDI in this real world, retrospective study. Analysis in a larger patient population is needed to confirm these findings.

Select Drug-Drug Interactions With Direct Oral Anticoagulants: JACC Review Topic of the Week

Millions of individuals in the United States require long-term treatment with an oral anticoagulant. For decades, vitamin K antagonists were the only oral option available; however, they have a number of well-known limitations. Introduction of the direct oral anticoagulants (DOACs) has long been considered a major therapeutic advance, largely because they lack the need for therapeutic monitoring. Despite this, DOACs, like vitamin K antagonists, can still cause major and clinically relevant nonmajor bleeding, even when used appropriately. Drug-drug interactions (DDIs) involving the DOACs represent an important contributor to increased bleeding risk. Awareness of these DDIs and how best to address them is of critical importance in optimizing management while mitigating bleeding risk. This review provides an overview of DOAC metabolism, the most common drugs likely to contribute to DOAC DDIs, their underlying mechanisms, and how best to address them.

The Magnitude of the Warfarin-Amiodarone Drug-Drug Interaction Varies With Renal Function: A Propensity-Matched Cohort Study

Amiodarone inhibits warfarin metabolism and is associated with major bleeding during warfarin therapy. Managing this drug-drug interaction (DDI) is challenging because of substantial interpatient variability in DDI magnitude. Because renal dysfunction induces changes in drug metabolism and protein binding that could alter cytochrome P450 inhibition mechanisms, we hypothesized that renal dysfunction alters the impact of the warfarin-amiodarone DDI. We tested this question in a propensity-matched cohort study of hospitalized patients with atrial fibrillation. Patients were queried from an electronic health record database. Renal function was estimated with creatinine clearance (CrCl). Warfarin response was measured with the warfarin sensitivity index (WSI), a dose-normalized international normalized ratio (INR) measure, and was modeled with multilevel mixed-effects linear regression. Time to supratherapeutic INR (> 4) was modeled using Cox regression. Propensity score matching resulted in 4,518 patients administered amiodarone and 4,518 controls. Amiodarone's effect on warfarin response varied threefold across the renal function range, increasing WSI by 36% in patients with normal renal function (CrCl 115 mL/minute), but by only 11.8% in patients with severe renal dysfunction (CrCl 15 mL/minute). Similarly, amiodarone had a strong effect in patients with normal renal function (hazard ratio (HR) 1.80; 1.23, 2.64), but a negligible effect on supratherapeutic INR hazard in patients with severe renal dysfunction (HR 1.01; 0.75, 1.37). These results suggest that renal function is a novel factor that explains substantial variability in the warfarin-amiodarone DDI. This information could inform warfarin dosage adjustment and monitoring and may have implications for the selection of oral anticoagulation agents in patients treated with amiodarone.

Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions

Oral anticoagulants are commonly prescribed but high risk to cause adverse events. Skilled drug interaction management is essential to ensure safe and effective use of these therapies. Clinically relevant interactions with warfarin include drugs that modify cytochrome 2C9, 3A4, or both. Drugs that modify p-glycoprotein may interact with all direct oral anticoagulants, and modifiers of cytochrome 3A4 may interact with rivaroxaban and apixaban. Antiplatelet agents, nonsteroidal anti-inflammatory drugs, and serotonergic agents, such as selective serotonin reuptake inhibitors, can increase risk of bleeding when combined with any oral anticoagulant, and concomitant use should be routinely assessed. New data on anticoagulant drug interactions are available almost daily, and therefore, it is vital that clinicians regularly search interaction databases and the literature for updated management strategies. Skilled drug interaction management will improve outcomes and prevent adverse events in patients taking oral anticoagulants.

Drug-drug interactions in an era of multiple anticoagulants: a focus on clinically relevant drug interactions

Oral anticoagulants are commonly prescribed but high risk to cause adverse events. Skilled drug interaction management is essential to ensure safe and effective use of these therapies. Clinically relevant interactions with warfarin include drugs that modify cytochrome 2C9, 3A4, or both. Drugs that modify p-glycoprotein may interact with all direct oral anticoagulants, and modifiers of cytochrome 3A4 may interact with rivaroxaban and apixaban. Antiplatelet agents, nonsteroidal anti-inflammatory drugs, and serotonergic agents, such as selective serotonin reuptake inhibitors, can increase risk of bleeding when combined with any oral anticoagulant, and concomitant use should be routinely assessed. New data on anticoagulant drug interactions are available almost daily, and therefore, it is vital that clinicians regularly search interaction databases and the literature for updated management strategies. Skilled drug interaction management will improve outcomes and prevent adverse events in patients taking oral anticoagulants.

Effect of ABCB1 genetic polymorphisms on the transport of rivaroxaban in HEK293 recombinant cell lines

Direct oral anticoagulants (DOAC) are substrates for the ABCB1 transporter (also called P-glycoprotein), an active efflux pump. ABCB1 polymorphisms have been previously reported to influence the pharmacokinetics of several drugs such as immunosuppressants and tyrosine kinase inhibitors. Recently, in vivo studies have suggested that genetic variants might contribute to the inter-individual variability in DOAC plasma concentrations. Therefore, we evaluated the in vitro effect of the most common coding ABCB1 single nucleotide polymorphisms (SNP), 1236 C > T-2677G > T-3435C > T, and the coding ABCB1 1199 G > A SNP on the transport activity towards rivaroxaban. HEK293 cells were transfected to overexpress the ABCB1 wild-type (1236C-2677G-3435C, 1199 G) or variant proteins (1236C-2677G-3435T, 1236T-2677T-3435T or 1199 A). ABCB1 expression decreased the intracellular accumulation of rivaroxaban, when compared to control cells. This confirms the involvement of ABCB1 in the active transport of rivaroxaban. However, the ABCB1 1236 C > T-2677G > T-3435C > T and 1199 G > A SNPs had no significant influence on the intracellular accumulation of rivaroxaban when compared to the wild-type protein. These results suggest that the ABCB1 coding SNPs investigated in the present study are unlikely to contribute to the inter-individual variability in rivaroxaban plasma concentrations.