Direct Oral Anticoagulants—Pharmacology, Drug Interactions, and Side Effects

Protein S contributes to the paradoxical increase in thrombin generation by low-dose dabigatran in the presence of thrombomodulin

Low dose of dabigatran paradoxically increased thrombin generation through inhibition of protein C activation. Protein S is a co-factor in the activation of protein C. However, the role of protein S in the enhancement of thrombin generation has not been addressed. Firstly, we measured thrombin generation by calibrated automated thrombinography (CAT) and prothrombin fragments 1+2 (F 1+2 ) assays. Secondly, we assessed activated protein C (APC) formation in normal or protein S-deficient plasma spiking with dabigatran. Then, protein C activation was measured. Finally, heavy chain of factor Va (FVa) and its degradation products were detected by western blot. CAT assay showed that 70-141 ng/ml dabigatran paradoxically increased thrombin generation in normal plasma. However, higher concentrations of dabigatran (283 ng/ml) suppressed the level of ETP. F 1+2 assay showed the similar results. In protein S-deficient or protein C-deficient plasma, the paradoxical increase in thrombin generation was absent. Level of generated APC was to a similar extent inhibited by dabigatran in normal and protein S-deficient plasma. Low-dose dabigatran inhibited the protein S-dependent inactivation of factor Va. Protein S participated in the paradoxical enhancement of thrombin generation in normal plasma spiking with low concentrations of dabigatran. Increased thrombin generation at low dabigatran can be explained by reduced thrombin-thrombomodulin mediated APC formation and subsequent reduced FVa inactivation that is protein S-dependent.

LC-MS/MS Method Assay for Simultaneous Determination of the Apixaban and Metformin in Rat Plasma: Assessment of Pharmacokinetic Drug-Drug Interaction Study

A simple, sensitive and accurate LC-MS/MS method was developed and validated for the simultaneous quantification of apixaban (APB) and metformin (MET) in rat plasma using rivaroxaban as internal standard (IS). An Inertsil ODS3 C18 column (150 × 4.6 mm, 5 μm) was used for chromatographic separation with isocratic elution. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 459.8 → 442.8 for APB, m/z 130.2 → 71.2 for MET, m/z 436.8 → 144.9 for IS. The procedure of method validation included selectivity, linearity, precision, accuracy, matrix effect, extraction recovery and stability were conducted according to the guidelines of EMA and FDA. The method was validated over the concentration range of 0.5-250 ng/mL for APB and 8-8000 ng/mL for MET. The intra- and inter-day precision and accuracy of the quality control samples exhibited relative standard deviations (RSD) < 12.5% and the accuracy values ranged from -8.6 to 12.4%. Recovery and matrix effect values variations were all less than 15%. After oral administration APB and MET to rats, the comparison of pharmacokinetic parameters of APB in the single and co-administrated groups showed significant difference in AUC(0-t) from 730.71 ± 121.31 to 573.07 ± 90.13 ng/mL·h, t1/2 from 5.86 ± 3.21 to 4.24 ± 1.15 h and Cmax from113.54 ± 24.04 to 159.42 ± 54.6 ng/mL. The comparison of pharmacokinetic parameters of MET in the single and co-administrated groups showed significant difference in t1/2 from 2.83 ± 1.81 to 3.97 ± 0.57 h and Cmax from 4015.76 ± 873.23 to 3153.6 ± 1012.51 ng/mL. The results indicated that drug-drug interactions (DDI) occurred might be owing to APB affect one or all of OCTs, MATE1, MATE2-K.

Relationship Amongst Vitamin K Status, Vitamin K Antagonist Use and Osteoarthritis: A Review

Vitamin K is essential for the carboxylation of the vitamin K-dependent proteins that are responsible for the suppression of matrix calcification. The use of vitamin K antagonists (VKAs) in patients with cardiovascular diseases could affect protein carboxylation and lead to the development of osteoarthritis (OA). This review aims to summarise the current evidence for the relationship between VKAs and OA. The literature search revealed that in observation studies, good vitamin K status, as reflected by the circulating level or protein carboxylation status of vitamin K, is associated positively with improved joint structural and functional indices and negatively associated with OA incidence. By contrast, in limited retrospective and prospective studies, the use of VKAs is associated positively with OA occurrence and knee/hip replacement. Pharmacological interactions between VKAs and various OA therapeutic agents exist and require careful monitoring and dosing. In conclusion, further epidemiological studies are warranted to verify the relationship between VKA use and OA to strengthen the evidence. Given that VKA use exerts potentially negative effects on joint health, intervention is required to protect the quality of life and mobility of patients.

Dabigatran-Induced Nephropathy and Gastrointestinal Bleeding and Its Successful Treatment with Idarucizumab: A Case Report

Recently, the atrial fibrillation treatment guidelines have been updated to now recommend Non-vitamin K antagonist oral anticoagulants (NOACs) as the preferred alternative to warfarin for systemic embolism and stroke prevention in patients with non-valvular atrial fibrillation. NOACs have major pharmacologic advantages over warfarin, although the most common complications are gastrointestinal bleeding and NOAC-induced nephropathy within 6 weeks after starting therapy, as several recent case-reports stated. We are reporting for the first time a chronic delayed adverse reaction (regularly reported to Authorities) observed in an 82-year-old woman 27 months after starting dabigatran (110 mg twice a day), characterized by concomitant gastrointestinal bleeding and nephropathy. Idarucizumab administration immediately improved both bleeding and renal parameters. Moreover, we are going to highlight the importance of the compliance, the adherence to the therapeutic plan and the supervision of the Hospital Pharmacy on drug prescriptions. In fact in our case, dabigatran was firstly prescribed by the neurologist and delivered by the hospital pharmacy, but the patient continued the treatment for 27 months, prescribed by general practitioner without any laboratory control. This lack of supervision certainly contributed to the onset of the adverse reaction reported.

Effectiveness and safety among direct oral anticoagulants in nonvalvular atrial fibrillation: A multi-database cohort study with meta-analysis

AIMS

There are conflicting signals in the literature about comparative safety and effectiveness of direct oral anticoagulants (DOACs) for nonvalvular atrial fibrillation (NVAF).

METHODS

We conducted multicentre matched cohort studies with secondary meta-analysis to assess safety and effectiveness of dabigatran, rivaroxaban and apixaban across 9 administrative healthcare databases. We included adults with NVAF initiating anticoagulation therapy (dabigatran, rivaroxaban or apixaban), and constructed 3 cohorts to compare DOACs pairwise. The primary outcome was pooled hazard ratio (pHR) of ischaemic stroke or systemic thromboembolism. Secondary outcomes included pHR of major bleeding, and a composite of stroke, major bleeding, or all-cause mortality. We used proportional hazard Cox regressions models, and pooled estimates were obtained with random effect meta-analyses.

RESULTS

The cohorts included 73 414 new users of dabigatran, 92 881 of rivaroxaban, and 61 284 of apixaban. After matching, the pHRs (95% confidence intervals) comparing rivaroxaban initiation to dabigatran were: 1.11 (0.93, 1.32) for ischaemic stroke or systemic thromboembolism, 1.26 (1.09, 1.46) for major bleeding, and 1.17 (1.05, 1.30) for the composite endpoint. For apixaban vs dabigatran, they were: 0.91 (0.74, 1.12) for ischaemic stroke or systemic thromboembolism, 0.89 (0.75, 1.05) for major bleeding, and 0.94 (0.78 to 1.14) for the composite endpoint. For apixaban vs rivaroxaban, they were: 0.85 (0.74, 0.99) for ischaemic stroke or systemic thromboembolism, 0.61 (0.53, 0.70) for major bleeding, and 0.82 (0.76, 0.88) for the composite endpoint.

CONCLUSION

We found that apixaban use is associated with lower risks of stroke and bleeding compared with rivaroxaban, and similar risks compared with dabigatran.

Pseudoaneurysm of the Superficial Femoral Artery after Knee Arthroscopy

An 84 year old gentleman underwent knee arthroscopy. He had x-ray proven left knee osteoarthritis. He had a number of medical co-morbidities including being on an anticoagulant for atrial fibrillation. He did not want a knee replacement. A knee arthroscopy was performed which confirmed severe left knee osteoarthritis. Debridement of degenerative meniscus was performed. Three weeks post-operatively, the patient presented to the emergency department complaining of swelling and pain in his lower limb. He underwent an ultrasound venogram to look for a deep venous thrombosis (DVT). He was diagnosed with a pseudoaneurysm (PSA) of the superficial femoral artery (SFA). Subsequently, he was referred to the vascular surgery service who treated the PSA with covered stenting. The thigh and knee pain dissipated almost immediately. We propose that this is the first PSA of the left SFA to be documented after a knee arthroscopy. The authors would like to acknowledge that knee arthroscopy for severe osteoarthritis is rarely performed in an octogenarian. However, as this patient had declined a total knee replacement (TKR) and injections were no longer providing him relief, knee arthroscopy was performed.

Surfing the Blood Coagulation Cascade: Insight into the Vital Factor Xa

Factor Xa (FXa) plays a key role in haemostasis, it is a central part of the blood coagulation cascade which catalyzes the production of thrombin and leads to clot formation and wound closure. Therefore, FXa is an attractive target for the development of new anticoagulant agents. In this review, we will first describe the molecular features of this fundamental protein in order to understand its mechanism of action, an essential background for the design of novel inhibitors by means of synthetic organic chemistry or using peptides obtained from recombinant methodologies. Then, we will review the current state of the synthesis of novel direct FXa inhibitors along with their mechanisms of action. Finally, approved reversal agents that aid in maintaining blood haemostasis by using these commercial drugs will also be discussed.

Interaction between Traditional Chinese Medicine and Anticoagulant/Antiplatelet Drugs

Background:

Traditional Chinese medicine (TCM) has been used for medical purposes since the ancient time and has gradually gained recognition worldwide. Nowadays, patients with thrombus presiding to anticoagulant/ antiplatelet drugs prefer taking TCM. However, an increasing number of studies on herb–drug interactions have been shown. Nevertheless, findings are frequently conflicting and vague. In this review, we discuss the herb–drug interactions between TCM and anticoagulant/antiplatelet drugs to provide guidance on concomitant ingestion with anticoagulant/antiplatelet drugs.

Methods:

We undertook a structured search of medicine and drug databases for peer-reviewed literature using focused review questions.

Results:

Danshen, Ginkgo, Ginger, H. Perforatum, SMY and Puerarin injection had directional regulation effects on the efficacy of anticoagulant drugs by altering the CYPs, pharmacokinetic indexs and hemorheological parameters. H. Perforatum inhibited the efficacy of Clopidogrel by enhancing the CYP3A4 activity and Ginkgo increased the efficacy of Ticlopidine. Additionally, Renshen, the formulae except SMY and injections except Puerarin injection could increase or decrease the efficacy of anticoagulant/antiplatelet drugs via regulating the CYPs, platelet aggregation, hemorheological parameters and others.

Conclusion:

Some cases have reported that TCMs may increase the bleeding risk or has no effect on coagulation when anticoagulant/antiplatelet drugs are concurrently used. However, pharmacokinetic studies have presented either consistent or slightly varying results. So it is difficult to ascertain whether the concurrent use of TCM may increase or reduce the pharmacologic effects of anticoagulant/antiplatelet drugs with adverse reactions. Therefore, herb–drug interactions of TCM and anticoagulant/antiplatelet drugs should be further explored and defined.

The efficacy and safety of direct oral anticoagulants in patients with chronic renal insufficiency: A review of the literature

Direct oral anticoagulants (DOACs) have been shown to be superior to vitamin K antagonists (VKAs) in regards to safety and efficacy in numerous clinical trials and are now the preferred oral anticoagulant by multiple professional societies. However, patients with significant levels of organ dysfunction were excluded from all major clinical trials, leaving the clinical benefit in these subsets uncertain. Patients with chronic kidney disease (CKD) specifically often require anticoagulation for acute or long-term indications such as venous thromboembolism, atrial fibrillation, or mechanical heart valves. The efficacy and safety of anticoagulation in patients with renal failure is less certain, however, particularly with DOACs which have altered pharmacokinetics in patients with renal failure and limited observational data on their use in this population. In this review, we compile the most up to date data on the DOAC use in patients with CKD. DOAC use in patients with ESRD and advanced CKD is increasing despite the presence of a clear benefit, and with the potential for increased risk of bleeding compared to warfarin. Apixaban has the greatest amount of outcomes research supporting its use over warfarin in this patient population; however, further research on DOAC safety and efficacy in those with advanced CKD is still needed.

Impact of Direct Oral Anticoagulants in Patients With Hip Fractures

OBJECTIVE

To assess the impact of direct oral anticoagulant (DOAC) intake compared with Coumadin (COU) in patients suffering hip fractures (HFs).

DESIGN

Retrospective cohort analysis.

SETTING

Level 1 Trauma Center.

INTERVENTION

Timing of surgical hip fixation.

PATIENTS

Three-hundred twenty patients 65 years of age or older with isolated HF were enrolled into the study: 207 (64.7%) without any antithrombotic therapy (no-ATT), 59 (18.4%) on COU, and 54 (16.9%) on DOACs.

MAIN OUTCOME MEASUREMENTS

Time to surgery, blood loss, mortality, hospital length of stay, red blood cell transfusion, use of reversal agents, and Charlson Comorbidity Index.

RESULTS

Patients on COU and DOACs had a higher Charlson Comorbidity Index compared with the no-ATT group (P < 0.0001). Despite the fact that significantly more patients received reversal agents in the COU group compared with DOAC medication (P < 0.0001), percentage of transfused patients were similar (54.2% vs. 53.7%). Time to surgery was significantly shorter in the no-ATT group when compared with DOAC patients (12-29.5 hours, respectively). No difference in postoperative hemorrhage, intensive care unit length of stay, and mortality was observed between groups.

CONCLUSIONS

DOAC medication in HF patients caused long elapse time until surgical repair. We found no evidence of higher bleeding rates in HF patients on DOACs compared with COUs. Earlier HF fixation might be indicated in DOAC patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

New antiplatelet drugs and new oral anticoagulants

In our daily anaesthetic practice, we are confronted with an increasing number of patients treated with either antiplatelet or anticoagulant agents. During the last decade, changes have occurred that make the handling of antithrombotic medication a challenging part of anaesthetic perioperative management. In this review, the authors discuss the most important antiplatelet and anticoagulant drugs, the perioperative management, the handling of bleeding complications, and the interpretation of some laboratory analyses related to these agents.

Cost Analysis of Direct Oral Anticoagulants Compared with Warfarin in Patients with Blunt Traumatic Intracranial Hemorrhages

Direct oral anticoagulants (DOACs) are rapidly gaining popularity as alternatives to warfarin in the prevention of stroke or systemic embolic events because of the simplicity of their dosing and lack of monitoring requirement. Many physicians feared that these novel agents would be cost-prohibitive not only in their administration but also in their sequelae of bleeding, given the few reversal agents available. Whereas the medication itself is more expensive than traditional warfarin, the total cost of a hospital admission has not been compared between patients on DOACs and warfarin who have sustained a blunt traumatic intracranial hemorrhage (ICH). We conducted a retrospective review of our hospital's trauma database from June 2011 through September 2015 at our Level II trauma center of patients who suffered from an ICH who were anticoagulated at the time of their trauma. Patients who died during their hospital admission or were exclusively on antiplatelet agents were excluded. Of the 136 patients studied, 79 were on warfarin and 57 were on a DOAC at the time of their presentation for a traumatic ICH. The average charged cost for the hospital stay of a patient with an ICH was significantly higher for patients on warfarin compared with DOACs [$70,384.08 vs $49,226.66 (P = 0.02)]. The average reimbursement rate for the hospital was also significantly higher for those patients on warfarin as compared with those on DOACs [$23,922.93 vs $14,705.77 (P = 0.02)]. DOACs are associated with a significant cost benefit in patients admitted for blunt traumatic ICHs when compared with those on warfarin.

Postoperative bleeding risk of direct oral anticoagulants after oral surgery procedures: a systematic review and meta-analysis

Direct oral anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban; DOACs) have been introduced to improve safety and superior therapeutic value compared to their predecessors such as warfarin or enoxaparin. The aim of this systematic review and meta-analysis was to assess the postoperative bleeding risk of DOACs during oral surgery procedures. Systematic searches were performed in electronic databases including PubMed, Scopus, Web of Science and Cochrane Library. Thirteen studies were included in the qualitative synthesis: two retrospective case-control studies, five prospective case-control studies, three cross-sectional studies, two case series and a case report; while only six studies were statistically analysed. The risk ratio of postoperative bleeding in DOACs patients was significantly greater than in healthy patients (3.04; 95% confidence interval (CI)=1.31-7.04). This is especially true for rivaroxaban (4.13; 95% CI=1.25-13.69), and less so for dabigatran which presented a risk ratio similar to that of healthy patients (1.00; 95% CI=0.21-4.82). However, further research is required to support these results. Both apixaban and edoxaban were excluded from statistical analysis due to the lack of clinical studies.

Management of Anticoagulation in Patients With Prostate Cancer Receiving Enzalutamide

Enzalutamide, a novel, oral androgen receptor antagonist used for the treatment of metastatic, castration-resistant prostate cancer, has been shown to improve overall and progression-free survival, prolong time to initiation of chemotherapy, reduce skeletal-related events, and carry a favorable adverse effect profile. Metastatic prostate cancer is a disease of older men, a population with an increased incidence of medical comorbidities warranting anticoagulation. Prostate cancer itself, along with some of its therapies, is also prothrombotic. Enzalutamide interacts with several anticoagulants through various mechanisms, making their concurrent use clinically challenging. As such, complex decisions about anticoagulation in these patients are frequently encountered by treating physicians. In this review, we describe the potential interactions between enzalutamide and various anticoagulants, and suggest management paradigms based on the current body of knowledge for patients with atrial fibrillation, venous thromboembolism, and mechanical heart valves.

Does type 2 diabetes affect the on-treatment levels of direct oral anticoagulants in patients with atrial fibrillation?

AIMS

Type 2 diabetes (T2D) is connected with several abnormalities in haemostasis; and with higher risk of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NV-AF). However, it is recently unknown whether T2D affects the activity of direct oral anticoagulants (DOACs). The aim of this study was to determine the impact of T2D on DOACs activity in patients with NV-AF.

METHODS

This pilot prospective study enrolled totally 65 patients with NV-AF (20 dabigatran-treated, 110 mg/twice daily; 28 rivaroxaban-treated, 15 mg/daily; 17 apixaban-treated, 5 mg/twice daily). 25 patients had T2D (8 dabigatran-treated, 11 rivaroxaban-treated, and 6 apixaban-treated). DOAC activity was tested with Hemoclot® Thrombin Inhibitor assay in dabigatran-treated patients, and with factor Xa-calibrated anti-Xa chromogenic analysis in rivaroxaban- and apixaban-treated patients prior and two hours after drug administration.

RESULTS

There were no significant differences in dabigatran baseline (62.1 ± 8.0 vs. 51.8 ± 38.9 ng/ml, p = .76) and 2-h-post-drug-administration (91.7 ± 57.2 vs. 72.2 ± 33.2 ng/ml, p = .48) activity comparing T2D and non-diabetic patients. Similarly, no significant differences were found in rivaroxaban baseline (35.9 ± 22.5 vs. 55.3 ± 45.1 ng/ml, p = .19) and 2-h-post-drug-administration (145.7 ± 74.1 vs. 202.6 ± 135.0 ng/ml, p = .22) anti-Xa activity. In addition, no significant differences were present in apixaban baseline (96.0 ± 54.5 vs. 63.9 ± 36.8 ng/ml, p = .24) and 2-h-post-drug-administration (151.0 ± 78.3 vs. 151.7 ± 59.1 ng/ml, p = .98) anti-Xa activity between T2D and non-diabetic patients.

CONCLUSIONS

This pilot study did not detect differences in DOACs activity according to T2D status in patients with NV-AF.

Apixaban Concentration with and without Coadministration of Carbamazepine: A Case with No Apparent Interaction

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Readmissions in Patients with Anticoagulated Intracranial Hemorrhage: A Retrospective Review

OBJECTIVE

To determine the effect of direct oral anticoagulants (DOACs) compared with warfarin on the 30-day readmission rates in patients with traumatic intracranial hemorrhage (ICH).

METHODS

We conducted a retrospective review of patients from our hospital's trauma database admitted between June 2011 and October 2015 to our level II trauma center after sustaining a traumatic ICH while receiving anticoagulant therapy. Patients were stratified based on the anticoagulation drug (DOAC or warfarin) prescribed on admission. The readmission rates between the 2 groups were compared using χ² analysis and multivariate logistic regression. Patients who died during their initial admission were excluded.

RESULTS

Over the 4-year period, 160 patients were admitted with traumatic ICH. Seventy-nine were receiving warfarin and 57 were receiving a DOAC at admission. Data collected included age, sex, injury severity score, admission Glasgow Coma Score, Abbreviated Injury Scale (head), mechanism of injury, hospital and intensive care unit lengths of stay, discharge destination (eg, home, rehabilitation facility, nursing facility), comorbidities, operative interventions, readmissions, and reasons for the readmissions. The rate of readmission for rebleeding of ICH was significantly lower in the DOAC group compared with the warfarin group (5.3% vs. 17.7%; P = 0.04). Multivariate logistic regression suggests that warfarin use, but not DOAC use, is associated with increased readmission both for all causes and for ICH rebleeding.

CONCLUSIONS

Warfarin use is associated with higher readmission rates in patients with intracranial bleeding for both all-cause readmissions and for intracranial rebleeding.

Spontaneous Superior Mesenteric Artery Branch Pseudoaneurysm: A Rare Case Report

Background

Visceral arterial pseudoaneurysms (VAPAs) are rare vascular entities with serious consequences. Traditionally, they are associated with trauma, infection, and inflammatory disease, or they can arise as a post-operative complication.

Report

An 87 year old man presented with abdominal pain and was found to have a spontaneous VAPA on a computed tomography angiogram. Serial imaging 4 months previously had demonstrated no aneurysm. Between scans, warfarin was changed to apixaban for aortic valve replacement, but he had no other changes to any other medications. He required urgent endovascular coiling of the pseudoaneurysm, with satisfactory recovery and outcome.

Discussion

VAPAs are extremely rare, with splenic artery VAPAs the most commonly reported. Regardless, fewer than 250 cases of splenic artery pseudoaneurysm have been reported. Superior mesenteric artery (SMA) pseudoaneurysms are the rarest type of VAPAs. Early identification and urgent treatment are warranted because of the associated high mortality risk, with a 50% risk of rupture in any given VAPA. Treatment options range from open operation to endoscopic and endovascular procedures. Apixaban has been proposed to contribute to pseudoaneurysm formation by slow and continuous bleeding that results in the formation of the pseudoaneurysm.

Conclusions

Spontaneous VAPAs are extremely rare and this is the first time a VAPA has been associated with the novel oral anticoagulant "apixaban". Urgent management of any VAPAs is important because of the high risk of rupture and potential life threatening haemorrhage.

Compared to warfarin, direct oral anticoagulants are associated with lower mortality in patients with blunt traumatic intracranial hemorrhage: A TQIP study

BACKGROUND

Falls represent the leading cause of traumatic brain injury in adults older than 65, with nearly one third experiencing a fall each year. Evidence suggests that up to 0.5% of anticoagulated patients suffer from intracranial hemorrhage (ICH) annually. Direct oral anticoagulants (DOACs) have become an increasingly popular alternative to warfarin for anticoagulation; however, there is a dearth of research regarding the safety of DOACs, in particular on the outcome of traumatic ICH while taking DOACs.

METHODS

We queried our Trauma Quality Improvement Project registry for patients who presented with traumatic intracranial hemorrhage during anticoagulant use. Patients were grouped into those prescribed warfarin and patients prescribed DOAC medications. The groups were compared with respect to age, gender, Glasgow Coma Score (GCS) on arrival, Abbreviated Injury Scale (AIS) (head), Injury Severity Score (ISS), mortality, need for operative intervention, hospital and ICU lengths of stay, proportion of patients transfused (and their transfusion requirements), and rates of discharge to skilled nursing facility. Poisson regression was conducted to determine the relationship between mortality and treatment group while controlling for covariates (comorbidities, ISS).

RESULTS

There were no differences between DOAC and warfarin groups in terms of age, gender, median ISS, median AIS head, or median admission GCS. Mechanisms of injury, median hospital and ICU lengths of stay, ICU free days, and transfusion requirements were also not significantly different.DOAC use was associated with significantly lower mortality (4.9% vs. 20.8%; p < 0.008) and a lower rate of operative intervention (8.2% vs. 26.7%; p = 0.023) when compared with warfarin. Excluding patients who died, the observed rate of discharge to skilled nursing facility was lower in the DOAC group (28.8% compared with 39.7%; p = 0.03). Multivariate Poisson regression analysis demonstrated that warfarin use was associated with an increased mortality when controlling for injury severity, and comorbidities.

CONCLUSIONS

We report improved mortality and reduced rates of operative intervention in patients with traumatic ICH associated with DOACs compared with a similar group taking warfarin. We also noted an association with decreased rate of discharge to SNF in patients taking DOACs compared with warfarin.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Direct oral anticoagulants compared with warfarin in patients with severe blunt trauma

METHODS

We queried our Trauma Quality Improvement Program registry for patients who presented between 6/1/2011 and 9/1/2015 with severe (injury severity score (ISS)>15) blunt traumatic injury during anticoagulant use. Patients were then grouped into those prescribed warfarin and patients prescribed any of the available novel Direct Oral Anticoagulants (DOAC) medications. We excluded severe (AIS≧4) head injuries.

RESULTS

There were no differences between DOAC and warfarin groups in terms of age, gender mean ISS, median hospital or intensive care unit lengths of stay, complication proportions, numbers of complications per patient, or the proportion of patients requiring transfusion. Finally, excluding patients who died, the observed proportion of discharge to skilled nursing facility was similar. In our sample of trauma patients, DOAC use was associated with significantly lower mortality (DOAC group 8.3% vs. warfarin group 29.5%, p<0.015). The ratio of units transfused per patient was also lower in the DOAC group (2.8±1.8 units/patient in the DOAC group vs. 6.7±6.4 units per patient in the warfarin group; p=0.001).

CONCLUSION

In conclusion, we report an association with decrease in mortality and a decrease in transfused blood products in severely injured trauma patients with likely minimal or no head injury taking novel DOACs over those anticoagulated with warfarin for outpatient anticoagulation.

Design, synthesis and biological evaluation of novel 2,3-dihydroquinazolin- 4(1H)-one derivatives as potential fXa inhibitors

Coagulation factor Xa (fXa) is a particularly attractive target for the development of effective and safe anticoagulants. In this study, novel 2,3-dihydroquinazolin-4(1H)-one derivatives were designed as potential fXa inhibitors based on anthranilamide structure which has been reported in our previous research. The experimental data showed that most of the designed compounds exhibited significant in vitro potency against fXa. Among them, compound 8e displayed the strongest potency against fXa with the IC₅₀ value of 21 nM and highly selectivity versus thrombin (IC₅₀ = 67 μM) and excellent in vitro antithrombotic activity with its 2 × PT value of 1.2 μM and 2 × aPTT value of 0.6 μM. In addition, 8e also displayed excellent in vivo antithrombotic activity in the rat arteriovenous shunt (AV-SHUNT) model. The bleeding risk evaluation showed that 8e had a similar safety profile as that of betrixaban. All results demonstrated that compound 8e could be considered as a potential fXa inhibitor for the prevention and treatment of thromboembolic diseases.

NOAC monitoring, reversal agents, and post-approval safety and effectiveness evaluation: A cardiac safety research consortium think tank

Four non-vitamin K antagonist oral anticoagulants (dabigatran, rivaroxaban, apixaban, and edoxaban) have been approved in the United States for treatment of atrial fibrillation (AF) and venous thromboembolic disease. They have been as or more effective than the prior standards of care, with less fatal or intracranial bleeding, fewer drug and dietary interactions, and greater patient convenience. Nonetheless, the absence of the ability for clinicians to assess compliance or washout with a simple laboratory test (or to adjust dosing with a similar assessment) and the absence of an antidote to rapidly stop major hemorrhage or to enhance safety in the setting of emergent or urgent surgery/procedures have been limitations to greater non-vitamin K antagonist oral anticoagulant usage and better thromboembolic prevention. Accordingly, a Cardiac Research Safety Consortium "think tank" meeting was held in February 2015 to address these concerns. This manuscript reports on the discussions held and the conclusions reached at that meeting.

Pharmacologic Therapies in Anticoagulation

Anticoagulants are beneficial for prevention and treatment of venous thromboembolism and stroke prevention in atrial fibrillation. The development of target-specific oral anticoagulants is changing the landscape of anticoagulation therapy and created growing interest on this subject. Understanding the pharmacology of different anticoagulants is the first step to adequately treat patients with best available therapy while avoiding serious bleeding complications. This article reviews the pharmacology of the main anticoagulant classes (vitamin K antagonists, direct oral anticoagulants, and heparins) and their clinical indications based on evidence-based data currently available in the literature.

Oral anticoagulants and risk of nephropathy

Anticoagulant-related nephropathy, a recently recognized entity, manifests as unexplained acute kidney injury in the setting of excessive anticoagulation with oral agents. Histologic findings in warfarin-related nephropathy include glomerular hemorrhage and renal tubular obstruction by red blood cells. Affected patients are at increased risk of mortality as well as irreversible kidney injury. Patients with chronic kidney disease are particularly vulnerable to this complication. Similar case reports of anticoagulant-related nephropathy have been linked to the more novel oral anticoagulant, dabigatran. Anticoagulant-related nephropathy has been successfully reproduced in rat models. These animal models shed light on the pathogenesis of the disease including the potential role of direct thrombin and protease-activated receptor-1 inhibition. Warfarin and dabigatran also cause an increase in systolic blood pressure in rats, a risk factor for developing nephropathy. This article reviews the current evidence for anticoagulant-related nephropathy and provides data for the suggested possible mechanisms underlying this adverse effect.

Clinical development of rivaroxaban: emerging new clinical evidences?

Rivaroxaban has proven efficacious in a variety of conditions. In fact, rivaroxaban has been approved for the prevention of venous thromboembolism after elective hip or knee replacement surgery, for the prevention and treatment of deep vein thrombosis and pulmonary embolism, for the prevention of stroke in patients with nonvalvular atrial fibrillation and for the prevention of atherothrombotic events after acute coronary syndrome with elevated cardiac biomarkers. However, clinical development of rivaroxaban is ongoing. Considering published and on-going randomized clinical trials, noninterventional studies and registries, over 275,000 patients are being analyzed. The aim of this review was to update the clinical development of rivaroxaban, including completed and ongoing studies not only randomized clinical trials, but also clinical practice studies.