Pharmacokinetics of new oral anticoagulants: implications for use in routine care

Structure and pharmacokinetics/pharmacodynamics of the anticoagulant tetradecasaccharide oHG-14 as an intrinsic tenase inhibitor

The intrinsic tenase complex (iXase) is an attractive antithrombotic target to treat or prevent pathological thrombosis with negligible bleeding risk. Fucosylated glycosaminoglycan (FG) is a promising anticoagulant by inhibiting iXase. A depolymerized FG (dHG-5) as an anticoagulant has been approved for clinical trials. Given that dHG-5 is a multi-component drug candidate consisting of a homologous series of oligosaccharides, it is difficult to predict a clear pharmacokinetics. Here, as a major oligosaccharide component, the tetradecasaccharide (oHG-14) was purified from dHG-5 and its structure was defined as L-Fuc3S4S-α(1,3)-L-Δ4,5GlcA-α(1,3)-{D-GalNAc4S6S-β(1,4)-[L-Fuc3S4S-α(1,]3)-D-GlcA-β(1,3)-}3-D-GalNAc4S6S-β(1,4)-[L-Fuc3S4S-α(1,]3)-D-GlcA-ol. oHG-14 showed potent iXase inhibitory activity in vitro and antithrombotic effect in vivo comparable to dHG-5. After single subcutaneous administration of oHG-14 at 8, 14.4 and 32.4 mg/kg to rats, the absolute bioavailability was 71.6 %-80.9 % determined by the validated bioanalytical methods. The maximum concentration (Cmax) was 3.73, 8.07, and 11.95 μg/mL, respectively, and the time reaching Cmax (Tmax) was about 1 h. oHG-14 was mainly excreted by kidney as the parent compound with the elimination kinetics of first-order linear model. Anticoagulant activity of oHG-14 was positively correlated with its concentration in rat plasma. The pharmacokinetics/pharmacodynamics (PK/PD) of oHG-14 is similar to that of dHG-5. This study could provide supportive data for the clinical trial of dHG-5 and further development of pure oligosaccharide as an antithrombotic drug candidate.

Comparison of warfarin, rivaroxaban, and dabigatran for effectiveness and safety in atrial fibrillation patients with different CHA2DS2-VASc scores: a retrospective cohort study

BACKGROUND

This retrospective cohort study aims to compare the effectiveness and safety of warfarin, rivaroxaban, and dabigatran in atrial fibrillation (AF) patients with different CHA2DS2-VASc scores in northern China.

METHODS

A retrospective cohort study was performed to evaluate anticoagulation in AF patients at the second affiliated hospital of Harbin Medical University from September 2018 to August 2019. Patients included in this study (n = 806) received warfarin (n = 300), or rivaroxaban (n = 203), or dabigatran (n = 303). Baseline characteristics and follow-up data including adherence, bleeding events and ischemic stroke (IS) events were collected.

RESULTS

Patients receiving rivaroxaban (73.9%) or dabigatran (73.6%) showed better adherence than those receiving warfarin (56.7%). Compared with warfarin-treated patients, dabigatran-treated patients had lower incidence of bleeding events (10.9% vs 19.3%, χ2 = 8.385, P = 0.004) and rivaroxaban-treated patients had lower incidence of major adverse cardiovascular events (7.4% vs 13.7%, χ2 = 4.822, P = 0.028). We classified patients into three groups based on CHA2DS2-VASc score (0-1, 2-3, ≥ 4). In dabigatran intervention, incidence of bleeding events was higher in patients with score 0-1 (20.0%) than those with score 2-3 (7.9%, χ2 = 5.772, P = 0.016) or score ≥ 4 (8.6%, χ2 = 4.682, P = 0.030). Patients with score 0-1 in warfarin or rivaroxaban therapy had a similar but not significant increase of bleeding compared with patients with score 2-3 or score ≥ 4, respectively. During the follow-up, 33 of 806 patients experienced IS and more than half (19, 57.6%) were patients with score ≥ 4. Comparing patients with score 0-1 and 2-3, the latter had an significant reduction of IS in patients prescribed warfarin and non-significant reduction in rivaroxaban and dabigatran therapy.

CONCLUSION

Compared with warfarin therapy, patients with different CHA2DS2-VASc scores receiving either rivaroxaban or dabigatran were associated with higher persistence. AF patients with score ≥ 4 were more likely to experience IS events while hemorrhagic tendency preferred patients with low score 0-1.

Exploring the level of agreement among different drug-drug interaction checkers: a comparative study on direct oral anticoagulants

BACKGROUND

Direct oral anticoagulants (DOACs) may be involved in drug-drug interactions (DDIs) potentially increasing the risk of adverse drug reactions. This study aimed to evaluate the level of agreement among interaction checkers (ICs) and DOACs' summary of product characteristics (SPCs), in listing DDIs and in attributing DDIs' severity.

RESEARCH DESIGN AND METHODS

The level of agreement among five ICs (i.e. INTERCheck WEB, Micromedex, Lexicomp, Epocrates, and drugs.com) in identifying potential DDIs and in attributing severity categories was evaluated using Gwet's AC1 on all five ICs and by comparing groups of four- and two-pair sets of ICs.

RESULTS

A total of 486 potentially interacting drugs with dabigatran, 556 for apixaban, 444 for edoxaban, and 561 for rivaroxaban were reported. The level of agreement among the ICs in identifying potential DDIs was poor (range: 0.12-0.16). Similarly, it was low in 4 and 2 sets analyses. The level of agreement among the ICs in classifying the severity of potential DDIs was poor (range: 0.32-0.34), also in 4 and 2 sets analyses.

CONCLUSIONS

The heterogeneity among different ICs and SPCs underscores the need to standardize DDI datasets and to conduct real-world studies to generate evidence regarding the frequency and clinical relevance of potential DOAC-related DDIs.

Risk of ischemic stroke associated with direct oral anticoagulants discontinuation on patients with non-valvular atrial fibrillation

INTRODUCTION

Although direct oral anticoagulants' (DOACs) prescriptions have experienced immense growth in the last decade, the proportion of discontinuers is still common yielding an increased risk of ischemic stroke (IS) onset.

AIMS

We aimed to estimate the association between DOACs discontinuation and risk of IS among patients with non-valvular atrial fibrillation (NVAF).

METHODS

We used data from a cohort of new DOACs users, followed patients from the first DOAC prescription date up to IS (index date) and conducted a nested case-control analysis using conditional logistic regression. Adjusted odds ratios, 95% confidence intervals were calculated for discontinuation of DOACs (current use compared with past use). The latter, subdivided among those stopping treatment 3 to 2 months and 6 and 3 months prior to index date. The effect of naïve current users against IS onset compared with non-naïve current users was also evaluated.

RESULTS

DOACs discontinuation showed an OR of IS of 1.47 (95% CI: 1.02-2.12); estimates were 2.51 (95% CI: 1.84-3.42) for whom discontinued treatment within months 3 and 2 and 1.43 (95% CI: 0.96-2.13) for those between months 6 and 3 prior to index date. Analyzing DOACs individually, risk of IS associated with past users compared with current users: 1.98 (95% CI: 1.25-3.12) for apixaban, 1.38 (95% CI: 0.40-4.72) for edoxaban, 1.98 (95% CI: 1.24-2.65) for dabigatran and 1.87 (95% CI: 1.26-2.76) for rivaroxaban. Similar results were found when stratified by naïve and non-naïve users.

CONCLUSIONS

DOACs' discontinuation is associated with higher risk of IS, especially in the second and third months following interruption.

Prevalence and factors associated with inappropriate dosing of apixaban and rivaroxaban in hospitalized older adults with atrial fibrillation: a cross-sectional study

INTRODUCTION

Atrial fibrillation (AF) is a common condition among older adults, requiring anticoagulation therapy to prevent thromboembolic events. Direct oral anticoagulants (DOACs) are now recommended as first-line therapy for this purpose. Apixaban and rivaroxaban are two direct-factor Xa inhibitors whose dosing is based on various factors (age, weight, creatinine, and creatinine clearance) that can affect the pharmacokinetics of the medication. This study aimed to evaluate factors associated with inappropriate dosing of apixaban or rivaroxaban based on the summary of product characteristics.

METHODS

A retrospective, single-center study included 777 hospitalizations of patients treated with apixaban or rivaroxaban for AF between 1 January 2018 and 31 December 2022. Primary endpoint assessed whether the dose of apixaban or rivaroxaban was within the summary of product characteristics used by European Medicine Agency (EMA).

RESULTS

Inappropriate dosing of apixaban or rivaroxaban is noted for approximately 30% of hospitalizations mostly underdosing. Factors associated with the risk of inappropriate dosing were the presence of cognitive impairment [adjusted odds ratio (OR*) 1.65, 95% confidence interval (CI) 1.19-2.29, p value (p) = 0.002], weight per kilogram increase (OR* 1.03, 95% CI 1.01-1.04, p < 0.0001), and history of bleeding under apixaban or rivaroxaban (OR* 1.94, 95% CI 1.24-3.03, p = 0.003).

CONCLUSION

This study highlighted the high prevalence of inappropriate apixaban or rivaroxaban doses in older adults, particularly underdosing, which increases the risk of thromboembolism.

Effectiveness and safety of direct oral anticoagulants versus warfarin in patients with atrial fibrillation and advanced kidney disease

BACKGROUND

The effectiveness and safety of direct oral anticoagulants (DOACs) in patients with atrial fibrillation (AF) and advanced kidney disease (AKD) has not been fully established.

OBJECTIVES

To determine the effectiveness and safety related to pooled or specific DOACs to that with warfarin in patients with AF and AKD.

METHODS

Patients with AF and AKD (estimated glomerular filtration rate < 30 mL/min) who received DOAC or warfarin from July 2011 to December 2020 were retrospectively identified in a medical center in Taiwan. Primary outcomes were hospitalized for stroke/systemic embolism and major bleeding. Secondary outcomes included any ischemia and any bleeding.

RESULTS

A total of 1,011 patients were recruited, of whom 809 (80.0%) were in the DOACs group (15.3% dabigatran, 25.4% rivaroxaban, 25.2% apixaban, and 14.1% edoxaban), and 202 (20.0%) in the warfarin group. DOACs had considerably lower risks of stroke/systemic embolism (adjusted hazard ratio [aHR] 0.29; 95% CI, 0.09-0.97) and any ischemia (aHR, 0.42; 95% CI, 0.22-0.79), but had comparable risks of major bleeding (aHR, 0.99; 95% CI, 0.34-2.92) and any bleeding (aHR, 0.74; 95% CI, 0.50-1.09) than warfarin. Apixaban was linked to considerably lower risks of any ischemia (aHR, 0.13; 95% CI, 0.04-0.48) and any bleeding (aHR, 0.53; 95% CI, 0.28-0.99) than warfarin.

CONCLUSION

Among patients with AF and AKD, DOACs were linked to a lower risk of ischemic events, and apixaban was linked to a lower risk of any ischemia and any bleeding than warfarin.

Atrial fibrillation and stroke

INTRODUCTION

Stroke is one of the leading causes of mortality and morbidity globally. Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. It is set to reach epidemic proportions. AF is associated with a five-fold increase in risk of stroke. Strokes caused by AF more often are fatal or result in severe disability. Even though the incidence of stroke has been significantly reduced by oral anticoagulation, AF is thought to account for a significant proportion of cryptogenic strokes where no etiology is identified.

AREAS COVERED

This article reviews the literature related to AF and stroke, pathophysiological insights, diagnosis of AF in stroke patients, and its management (Graphical Abstract).

EXPERT OPINION

The pathophysiology of thrombogenesis that links AF and stroke is not well understood and is an area of active research to identify new therapeutic targets to prevent AF and stroke. As the nature of AF and stroke is multifaceted, an integrated care approach to managing AF and stroke is increasingly essential.

Impact of increased kidney function on clinical and biological outcomes in real-world patients treated with Direct Oral Anticoagulants

BACKGROUND AND PURPOSE

Renal excretion of direct oral anticoagulants (DOACs) varies depending on the drug. Hypothetically, an increased glomerular filtration rate (GFR) may lead to suboptimal dosing and a higher thromboembolic events incidence. However, real-world patient data do not support the theoretical risk. The aim is to analyse DOAC outcomes in patients with normal and high (≥90 mL/min) GFR, focusing on biological parameters and thrombotic/haemorrhagic events.

METHODS

Observational prospective single-centre study and registry of patients on DOACs. Follow-up was 1,343 patient-years. A bivariate analysis was performed of baseline variables according to GFR (<90 mL/min vs ≥90 mL/min). Anti-Xa activity before and after drug intake (HemosIL, Liquid Anti-Xa, Werfen) was measured for edoxaban, apixaban, and rivaroxaban; diluted thrombin time for dabigatran (HEMOCLOT); and additionally, plasma concentrations in edoxaban (HemosIl, Liquid Anti-Xa suitably calibrated).

RESULTS

1,135 patients anticoagulated with DOACs were included and 152 patients with GFR ≥90 mL/min. Of 18 serious thrombotic complications during follow-up, 17 occurred in patients with GFR <90 mL/min, and 1 in a patient with GFR ≥90 mL/min. A higher incidence of complications was observed in patients with normal GFR, but the difference was not statistically significant (p>0.05). No statistically significant differences with clinical relevance were observed between the normal or supranormal groups in anti-Xa activity or in edoxaban plasma concentrations.

CONCLUSIONS

There was no increased incidence of thrombotic/haemorrhagic complications in our patients treated with DOACs, including 66% treated with edoxaban, and patients with GFR ≥90 mL/min. Likewise, drug anti-Xa activity and edoxaban plasma concentration did not seem to be influenced by GFR.

Early Surgical Care of Anticoagulated Hip Fracture Patients Is Feasible-A Retrospective Chart Review of Hip Fracture Patients Treated with Hip Arthroplasty within 24 Hours

Anticoagulative medication such as antiplatelet drugs (PAI, acetylsalicylic acid and direct platelet aggregation inhibitors), vitamin-K-antagonist Warfarin (VKA) or direct oral anticoagulants (DOAC) are common among hip fracture patients, and the perioperative management of these patients is a rising challenge in orthopaedic trauma. Our objective was to determine the effect of oral anticoagulation in patients receiving early endoprosthetic treatment within 24 h after their admission. For the period from 2016 to 2020, a retrospective chart review of 221 patients (mean age 83 ± 7 years; 161 women and 60 men) who were treated either with hemi- (n = 209) or total hip arthroplasty (n = 12) within 24 h after their admission was performed. We identified 68 patients who took PAI, 34 who took DOAC and 9 who took VKA medications. The primary outcome measures were the transfusion rate and the pre- and postoperative haemoglobin (Hb) difference. The secondary outcome measures were the in-patient mortality and the rate of postoperative haematomas that needed operative treatment. A logistic/ordinal regression was performed considering the related variables to prevent cofounding occurring. The mean time to surgery was significantly longer for the DOAC and VKA groups when they were compared to the controls (none 14.7 ± 7.0 h; PAI 12.9 ± 6.7 h; DOAC 18.6 ± 6.3 h; VKA 19.4 ± 5.5 h; p < 0.05). There was no difference in the preoperative Hb level between the groups. Overall, 62 patients (28%) needed blood transfusions during the in-patient stay with an ASA classification (p = 0.022), but the type of anticoagulative medication was not a significant predictor in the logistic regression. Anticoagulation with DOAC and grouped surgery times were positive predictors for a higher Hb difference in the patients who did not undergo an intraoperative blood transfusion (n = 159). Postoperative haematomas only occurred in patients taking anticoagulative medication (four cases in PAI group, and three cases in DOAC group), but the logistic regression showed that the anticoagulative medication had no effect. The in-patient mortality was significantly influenced by a high ASA grade (p = 0.008), but not by the type of anticoagulative medication in patients who were treated within 24 h. We conclude that the early endoprosthetic treatment of the anticoagulated hip fracture patient is safe, and a delayed surgical treatment is no longer justifiable.

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.

Role of Direct Oral Anticoagulants for Post-operative Venous Thromboembolism Prophylaxis

Venous thromboembolism (VTE) is one of the leading causes of post-operative morbidity and mortality. Over previous decades, heparin and warfarin were the predominant therapeutic options for post-operative thromboprophylaxis. However, their use is limited by drawbacks including a narrow therapeutic range, numerous food and drug interactions, and the need for regular monitoring for dose adjustments. Recently, direct oral anticoagulants (DOACs), such as dabigatran etexilate (a direct thrombin inhibitor) and apixaban, rivaroxaban and edoxaban (direct factor Xa inhibitors), have been developed to overcome these issues. DOACs have shown promising results in Phase III clinical trials for post-operative VTE prophylaxis. This review summarises the pharmacological profile of DOACs and highlights the use of DOACs in post-operative VTE prophylaxis based on the available clinical trial data.

Evaluation of Apixaban safety and effectiveness in morbidly obese patients with atrial fibrillation: a retrospective cohort study

Background

The benefit of apixaban to reduce stroke risk in morbidly obese patients with nonvalvular atrial fibrillation (AF) is still undetermined. The International Society of Thrombosis and Hemostasis recommends avoiding the use of direct oral anticoagulants (DOAC)s in morbidly obese patients (body mass index > 40 or weight > 120 kg) because of limited clinical data. This exploratory study aims to evaluate the effectiveness and safety of using apixaban in morbidly obese (body mass index (BMI) ≥ 40) patients with AF.

Methods

An exploratory retrospective cohort study was conducted at a single-center, including adult patients with non-valvular AF using apixaban between 01/01/2016 and 31/12/2019. Patients were excluded if they were known to have liver cirrhosis Child-Pugh C, mechanical valve, serum creatinine > 1.5 mg/dL, follow up < 3 months, or using apixaban with a dose of ≤5 or > 10 mg/day. Included patients were categorized into two groups based on their BMI (BMI<40 Vs. BMI ≥ 40). The primary outcome was all thrombotic events, while the secondary outcomes were major and minor bleeding after apixaban initiation. Propensity score (PS) matching was used (1:1 ratio) based on the patient’s age, gender, and HAS-BLED score.

Results

A total of 722 patients were eligible; 254 patients were included after propensity score matching based on the selected criteria. The prevalence of all thrombotic events was similar between the two groups in the first year of apixaban initiation (OR (95%CI): 0.58 (0.13, 2.5), p-value = 0.46). In addition, the odds of developing major and minor bleeding were not statistically significant between the two groups (OR (95%CI): 0.39 (0.07, 2.03), p-value = 0.26 and OR (95%CI): 1.27 (0.56, 2.84), p-value = 0.40), respectively).

Conclusion

This exploratory study showed similar effectiveness and safety of apixaban use in both morbid and non-morbid obese patients with non-valvular AF. However, a larger randomized controlled trial with a longer follow-up period needs to confirm our findings.

Major Bleeding Risk in Atrial Fibrillation Patients Co-Medicated With Non-Vitamin K Oral Anticoagulants and Antipsychotics

Major bleeding risks associated with non-vitamin K oral anticoagulants (NOACs) used with and without concurrent antipsychotics in patients with non-valvular atrial fibrillation (AF) were assessed. A total of 98,863 patients with non-valvular AF receiving at least one NOAC prescription from Taiwan’s National Health Insurance database were enrolled. Major bleeding was defined as a primary diagnosis of intracranial or gastrointestinal hemorrhage or bleeding at other sites. The adjusted incidence rate difference (AIRD) per 1,000 person-years and adjusted rate ratio of major bleeding were estimated using Poisson regression and inverse probability of treatment weighting using the propensity score. A total of 8,037 major bleeding events occurred during 705,521 person-quarters with NOAC prescriptions. Antipsychotics were used in 26.35% of NOAC-exposed patients. Compared to using NOAC alone, co-medication of either typical (AIRD: 79.18, 95% confidence interval [CI]: 70.63–87.72) or atypical (AIRD: 40.5, 95% CI: 33.64–47.35) antipsychotic with NOAC had a significant increase in the adjusted incidence rate per 1,000 person-years of major bleeding. The concomitant use of a NOAC with chlorpromazine (AIRD: 103.87, 95% CI: 51.22–156.52), haloperidol (AIRD: 149.52, 95% CI: 125.03–174.00), prochlorperazine (AIRD: 90.43, 95% CI: 78.55–102.32), quetiapine (AIRD: 44.6, 95% CI: 37.11–52.09), or risperidone (AIRD: 41.55, 95% CI: 22.86–60.24) (All p < 0.01) showed a higher adjusted incidence rate of major bleeding than using NOACs alone. The concomitant use of typical (chlorpromazine, haloperidol, or prochlorperazine) or atypical (quetiapine or risperidone) antipsychotic with NOACs was associated with a significantly increased risk of major bleeding.

Biopharmaceutics considerations for direct oral anticoagulants

Vitamin K antagonists (VKA) and direct oral anticoagulants (DOACs) have been clinically used in the treatment of coagulation disorders. There are four DOACs approved since 2010 (dabigatran etexilate, rivaroxaban, apixaban, and edoxaban), and they were designed to overcome the practical limitations of VKA. This review summarized biopharmaceutics considerations about DOACs, which are critically discussed, applying risk analyses to subside the further classification of these drugs according to the Biopharmaceutics Classification System (BCS). These discussions included data compiled about physicochemical properties, equilibrium solubility, permeability, and drug dissolution of DOACs. From the biopharmaceutics characteristics is possible to identify critical variables related to the absorption process, which can help in the design of new formulations. The data were compared with the criteria recommended by regulatory agencies for the biopharmaceutics classification according to the BCS. From that, these data may be used to discuss the approval of generic medicines by the BCS-based biowaiver, and the clinical risks arising from novel formulations with DOACs. However, although there are indications of biopharmaceutics classifications for DOACs, conclusive information to classify these compounds according to the BCS is lacking, requiring more experimental studies to achieve this aim. Conclusive information is essential for a safe decision about the biowaiver, as well as to guide the development of new formulations containing the DOACs.

Risk of Intracranial Hemorrhage Caused by Direct Oral Anticoagulants for Stroke Prevention in Patients With Atrial Fibrillation (from a Network Meta-Analysis of Randomized Controlled Trials)

Patients with atrial fibrillation (AF) who take direct oral anticoagulants (DOACs) face the risk of intracranial hemorrhage (ICH), which can be serious and even life threatening, but the risk of ICH of anticoagulants is still controversial. In this meta-analysis, we compared the risk of ICH between vitamin K antagonists (VKAs) and DOACs. Furthermore, we also compared the risk of ICH in different DOACs. PubMed, Embase, Web of Science, and the Cochrane Library were searched for relevant randomized controlled trials. The outcome was ICH, shown as the odds ratio (OR) with a 95% confidence interval (CI). DOACs were ranked by calculating the surface under the cumulative ranking curve (SUCRA). We included a total of 82,404 patients with AF. DOACs reduced the ICH risk by nearly half compared with VKAs (OR 0.47, 95% CI 0.40 to 0.54, p <0.001). VKAs were the least safe among all oral anticoagulants (SUCRA 1.7). Dabigatran 110 mg was the safest DOAC (SUCRA 87.3) for ICH risk, whereas rivaroxaban 20 mg was a relatively unsafe DOAC (SUCRA 27.5). Compared with rivaroxaban 20 mg, dabigatran 110 mg presented 53% (OR 0.47, 95% CI 0.27 to 0.82) lower relative risk for ICH. In conclusion, DOACs present less ICH risk than VKAs in patients with AF. For patients with AF who are at high risk of ICH, dabigatran 110 mg may be the safest choice among the DOACs.

Analysis of Influencing Factors of Compliance with Non-Vitamin K Antagonist Oral Anticoagulant in Patients with Nonvalvular Atrial Fibrillation and Correlation with the Severity of Ischemic Stroke

Nonvalvular atrial fibrillation (NVAF) is associated with an increased risk of stroke and thrombus, and anticoagulant therapy is a key link in the prevention of stroke. At present, the anticoagulation rate of atrial fibrillation in China is low, and there are many factors affecting the adherence of patients with atrial fibrillation to anticoagulation. Non-vitamin K antagonist oral anticoagulants (NOACs) are anticoagulant with high application value due to their high safety and low risk of intracranial hemorrhage, stroke, and death. However, the compliance of NOACs is poor, and the current situation of anticoagulants in China is not optimistic. In this study, a total of 156 patients with NVAF who received NOAC anticoagulation therapy in our hospital from January 2018 to January 2019 were retrospectively analyzed. The results showed that education background, place of residence, number of complications, CHA2DS2-VASc score, and HAS-BLED score were independent influencing factors for NOACS compliance of NVAF patients. Also, the Pearson correlation analysis showed that there was a negative correlation (r = −0.465, P < 0.001) between NOAC compliance and severity of ischemic stroke in patients with NVAF. Therefore, clinical supervision and management of patients with NVAF after NOACs should be strengthened to improve the compliance of patients with NVAF after NOACs, reduce the damage of ischemic stroke, and improve their prognosis.

How to handle the delayed or missed dose of rivaroxaban in patients with non-valvular atrial fibrillation: model-informed remedial dosing

BACKGROUND

Rivaroxaban is an oral anticoagulant widely used for stroke prevention in patients with non-valvular atrial fibrillation (NVAF). During long-term anticoagulant therapy, delayed or missed doses are common. This study aimed to explore appropriate remedial dosing regimens for non-adherent rivaroxaban-treated patients.

METHODS

Monte Carlo simulation based on a previously established rivaroxaban population pharmacokinetic/pharmacodynamic (PK/PD) model for patients with NVAF was employed to design remedial dosing regimens. The proposed regimens were compared with remedial strategies in the European Heart Rhythm Association (EHRA) guide by assessing deviation time in terms of drug concentration, factor Xa activity, and prothrombin time.

RESULTS

The proposed remedial dosing regimens were dependent on delay duration. The missed dose should be taken immediately when the delay does not exceed 6 h; a half dose is advisable when the delay is between 6 and 20 h. A missed dose should be skipped if less than 4 h remains before the next dose. The proposed regimens resulted in shorter deviation time than that of the EHRA guide.

CONCLUSION

PK/PD modeling and simulation provide valid evidence on the remedial dosing regimen of rivaroxaban, which could help to minimize the risk of bleeding and thromboembolism.

Characteristics, Location, and Clinical Outcomes of Gastrointestinal Bleeding in Patients Taking New Oral Anticoagulants Compared to Vitamin K Antagonists

New oral anticoagulants (NOACs) are commonly used in clinical practice as alternatives to vitamin K antagonists (VKA). However, the etiology, clinical course, and risk of gastrointestinal (GI) bleeding remain unclear. We aimed to evaluate the clinical characteristics and location of acute GI bleeding associated with NOACs and its severity and outcomes compared to VKA. This retrospective multicenter study included 381 subjects on anticoagulants who underwent appropriate diagnostic examination due to GI bleeding. Regarding the characteristics of acute GI bleeding, the proportion of vascular lesions was significantly lower in the NOACs group than that in the VKA group. Small bowel bleeding occurred less commonly in the NOACs group, but the difference did not reach statistical significance. Regarding severity and clinical outcomes, patients on NOACs received significantly smaller volumes of transfused blood products and had shorter ICU stays than those on VKA. Moreover, the need for surgery and the risk of rebleeding in the NOACs group were significantly lower than those in the VKA group. Patients on NOACs have better clinical outcomes in terms of severity of acute GI bleeding or rebleeding than patients on VKA. Patients on NOACs demonstrate different characteristics and location of acute GI bleeding than those on VKA.

ERS statement on chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare complication of acute pulmonary embolism, either symptomatic or not. The occlusion of proximal pulmonary arteries by fibrotic intravascular material, in combination with a secondary microvasculopathy of vessels <500 µm, leads to increased pulmonary vascular resistance and progressive right heart failure. The mechanism responsible for the transformation of red clots into fibrotic material remnants has not yet been elucidated. In patients with pulmonary hypertension, the diagnosis is suspected when a ventilation/perfusion lung scan shows mismatched perfusion defects, and confirmed by right heart catheterisation and vascular imaging. Today, in addition to lifelong anticoagulation, treatment modalities include surgery, angioplasty and medical treatment according to the localisation and characteristics of the lesions.This statement outlines a review of the literature and current practice concerning diagnosis and management of CTEPH. It covers the definitions, diagnosis, epidemiology, follow-up after acute pulmonary embolism, pathophysiology, treatment by pulmonary endarterectomy, balloon pulmonary angioplasty, drugs and their combination, rehabilitation and new lines of research in CTEPH.It represents the first collaboration of the European Respiratory Society, the International CTEPH Association and the European Reference Network-Lung in the pulmonary hypertension domain. The statement summarises current knowledge, but does not make formal recommendations for clinical practice.

Pharmacokinetics and Pharmacodynamics of a Depolymerized Glycosaminoglycan from Holothuria fuscopunctata, a Novel Anticoagulant Candidate, in Rats by Bioanalytical Methods

dHG-5 (Mw 5.3 kD) is a depolymerized glycosaminoglycan from sea cucumber Holothuria fuscopunctata. As a selective inhibitor of intrinsic Xase (iXase), preclinical study showed it was a promising anticoagulant candidate without obvious bleeding risk. In this work, two bioanalytical methods based on the anti-iXase and activated partial thromboplastin time (APTT) prolongation activities were established and validated to determine dHG-5 concentrations in plasma and urine samples. After single subcutaneous administration of dHG-5 at 5, 9, and 16.2 mg/kg to rats, the time to peak concentration (Tmax) was at about 1 h, and the peak concentration (Cmax) was 2.70, 6.50, and 10.11 μg/mL, respectively. The plasma elimination half-life(T1/2β) was also about 1 h and dHG-5 could be almost completely absorbed after s.c. administration. Additionally, the pharmacodynamics of dHG-5 was positively correlated with its pharmacokinetics, as determined by rat plasma APTT and anti-iXase method, respectively. dHG-5 was mainly excreted by urine as the unchanged parent drug and about 60% was excreted within 48 h. The results suggested that dHG-5 could be almost completely absorbed after subcutaneous injection and the pharmacokinetics of dHG-5 are predictable. Studying pharmacokinetics of dHG-5 could provide valuable information for future clinical studies.

Comparison of Direct Oral Anticoagulant Use for the Treatment of Non-Valvular Atrial Fibrillation in Pivotal Clinical Trials vs. the Real-World Setting: A Population-Based Study from Southern Italy

Patients enrolled into pivotal randomized controlled trials (RCTs) may differ substantially from those treated in a real-world (RW) setting, which may result in a different benefit–risk profile. The aim of the study was to assess the external validity of pivotal RCT findings concerning direct oral anticoagulants (DOACs) for the treatment of nonvalvular atrial fibrillation (NVAF) by comparing patients recruited in RCTs to those treated with DOACs registered in a southern Italian local health unit (LHU) in the years 2013–2017. The Palermo LHU claims database was used to describe the baseline characteristics of incident DOAC users (washout > 1 year) with NVAF compared with those of enrolled patients in DOAC pivotal RCTs. In the RW, DOAC treatment discontinuation was calculated during the follow-up and compared with DOAC treatment discontinuation of enrolled patients in DOAC pivotal RCTs. Rates of effectiveness and safety outcomes during the follow-up were calculated in an unmatched and in a simulated RCT population, by matching individual incidental RW and RCT DOAC users (excluding edoxaban users) on age, sex, and CHADS₂ score. Overall, 42,336 and 7092 incident DOAC users with NVAF were identified from pivotal RCTs and from the RW setting, respectively. In RCTs, DOAC use was more common among males (62.6%) compared with an almost equal sex distribution in the RW. RCT patients were younger (mean age ± standard deviation: 70.7 ± 9.2 years) than RW patients (76.0 ± 8.6 years). Compared with RCTs, a higher proportion of RW dabigatran users (30.4% vs. 19.6%) and a lower proportion of RW apixaban (15.9% vs. 25.3%) and rivaroxaban (20.4% vs. 23.7%) users discontinued the treatment during the follow-up (p-value < 0.001). The rate of ischemic stroke was lower in RW high-dose dabigatran users (unmatched/-matched population: 0.40–0.11% per year) than in the Randomized Evaluation of Long-Term Anticoagulation Therapy (RE-LY) population (0.93% per year). Major bleeding rates were lower in RW users than in RCT users. In conclusion, except for dabigatran, a lower proportion of DOAC discontinuers was observed in the real-world than in pivotal RCT settings. This study provides reassurance to practicing physicians that DOAC use appears to be effective in stroke prevention and is likely safer in RW patients than in RCT enrolled patients. These results may be related to a lower burden of comorbidities despite more advanced age in the RW population compared to the pivotal RCT population.

Prevalence and Impact of Nonalcoholic Fatty Liver Disease in Atrial Fibrillation

OBJECTIVE

To estimate the prevalence of nonalcoholic fatty liver disease (NAFLD) and its impact on bleeding and thrombotic events in patients with atrial fibrillation (AF).

PATIENTS AND METHODS

Prospective multicenter cohort study including patients with nonvalvular AF receiving vitamin K antagonists (VKAs) or non-VKA oral anticoagulants (NOACs) from February 2008 for patients on VKA and from September 2013 for patients on NOACs. NAFLD was diagnosed using the validated fatty liver index, with a cutoff score of 60 or higher. Primary end points were the occurrence of major bleedings and cardiovascular events (CVEs).

RESULTS

NAFLD was diagnosed in 732 of 1735 (42.2%) patients. Patients with NAFLD were younger, less frequently women, and more likely to be treated with NOACs and to have obesity, dyslipidemia, and persistent/permanent AF. During a median follow-up of 18.7 months (3155 patient-years), we recorded 78 major bleedings (incidence rate, 2.5% per year): 29 (2.1% per year) in patients with and 49 (2.7% per year) in patients without NAFLD (log-rank test P=.23). Univariate Cox proportional regression analysis showed no association of NAFLD with major bleedings (hazard ratio, 0.75; 95% CI, 0.47-1.20; P=.23). One hundred fifty-five CVEs occurred (incidence rate, 3.1% per year). No significant association was found between NAFLD and CVEs (log-rank test P=.12). In the entire population, NOAC use was associated with lower CVEs compared with VKAs (hazard ratio, 0.61; 95% CI, 0.42-0.89; P=.01).

CONCLUSION

NAFLD is highly prevalent in AF but is not associated with higher bleeding or thrombotic risk.

Factor XI(a) inhibitors for thrombosis: an updated patent review (2016-present)

Introduction: Anticoagulation without bleeding is an ideal goal in treating thrombosis, however, this goal has not been achieved. All current anticoagulants are associated with significant bleeding which limits their safe use. Genetic and pharmacological findings indicate that factor XIa is a key player in thrombosis, yet it is a relatively marginal one in hemostasis. Thus, factor XIa and its zymogen offer a unique opportunity to develop anticoagulants with low bleeding risk.Areas covered: A survey of patent literature has retrieved more than 50 patents on the discovery of novel therapeutics targeting factor XI(a) since 2016. Small molecules, monoclonal antibodies, oligonucleotides, and polypeptides have been developed to inhibit factor XI(a). Many inhibitors are in early development and few have been evaluated in clinical trials.Expert opinion: Factor XI(a) is being actively pursued as a drug target for the development of effective and safer anticoagulants. Although many patents claiming factor XI(a) inhibitors were filed prior to 2016, recent literature reveals a moderately declining trend. Nevertheless, more agents have entered different levels of clinical trials. These agents exploit diverse mechanistic strategies for inhibition. Although further development is warranted, reaching one or more of these agents to the clinic will transform the anticoagulation therapy.

Pharmacokinetics and pharmacodynamics of oral anticoagulants used in atrial fibrillation

INTRODUCTION

The availability of non-vitamin K antagonist oral anti-coagulants alongside vitamin K antagonists has offered a variety of options for anti-coagulation, but has also necessitated a good understanding of the pharmacological properties of each of these drugs prior to their use, to maximise the therapeutic benefit and minimise patient harm Areas covered: This review article outlines the pharmacokinetic and pharmacodynamic profiles of the currently licensed VKAs and NOACs that are most commonly used in clinical practice, with the aim of demonstrating how variations in these characteristics influence their use in clinical practice. A literature search was conducted on PubMed using keywords and relevant articles published by the 31^st of December 2018 were included. Expert opinion: The effect of a drug is determined by a combination of elements which include patient characteristics and external factors, in addition to its pharmacokinetic and pharmacodynamic properties. A good understanding of these is essential. Despite the wealth of information available, particularly on VKAs, our knowledge on the pharmacology responsible for certain drug effects and inter-individual variations is still limited. Increasing efforts are being made to understand these and include focus on pharmacogenomics and drug transporter proteins.

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

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

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

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

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

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

Pharmacokinetic Interactions of Clinical Interest Between Direct Oral Anticoagulants and Antiepileptic Drugs

Direct oral anticoagulants (DOACs), namely apixaban, dabigatran, edoxaban, and rivaroxaban are being increasingly prescribed among the general population, as they are considered to be associated to lower bleeding risk than classical anticoagulants, and do not require coagulation monitoring. Likewise, DOACs are increasingly concomitantly prescribed in patients with epilepsy taking, therefore, antiepileptic drugs (AEDs), above all among the elderly. As a result, potential interactions may cause an increased risk of DOAC-related bleeding or a reduced antithrombotic efficacy. The objective of the present review is to describe the pharmacokinetic interactions between AEDs and DOACs of clinical relevance. We observed that there are only few clinical reports in which such interactions have been described in patients. More data are available on the pharmacokinetics of both drugs classes which allow speculating on their potential interactions. Older AEDs, acting on cytochrome P450 isoenzymes, and especially on CYP3A4, such as phenobarbital, phenytoin, and carbamazepine are more likely to significantly reduce the anticoagulant effect of DOACs (especially rivaroxaban, apixaban, and edoxaban). Newer AEDs not affecting significantly CYP or P-gp, such as lamotrigine, or pregabalin are not likely to affect DOACs efficacy. Zonisamide and lacosamide, which do not affect significantly CYP activity in vitro, might have a quite safe profile, even though their effects on P-gp are not well-known, yet. Levetiracetam exerts only a potential effect on P-gp activity, and thus it might be safe, as well. In conclusion, there are only few case reports and limited evidence on interactions between DOACs and AEDs in patients. However, the overall evidence suggests that the interaction between these drug classes might be of high clinical relevance and therefore further studies in larger patients' cohorts are warranted for the future in order to better clarify their pharmacokinetic and define the most appropriate clinical behavior.