Dabigatran-Associated Intracranial Hemorrhage: Literature Review and Institutional Experience

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Addressing the Needs of the Rapidly Aging Society through the Development of Multifunctional Bioactive Coatings for Orthopedic Applications

The unprecedented aging of the world's population will boost the need for orthopedic implants and expose their current limitations to a greater extent due to the medical complexity of elderly patients and longer indwelling times of the implanted materials. Biocompatible metals with multifunctional bioactive coatings promise to provide the means for the controlled and tailorable release of different medications for patient-specific treatment while prolonging the material's lifespan and thus improving the surgical outcome. The objective of this work is to provide a review of several groups of biocompatible materials that might be utilized as constituents for the development of multifunctional bioactive coatings on metal materials with a focus on antimicrobial, pain-relieving, and anticoagulant properties. Moreover, the review presents a summary of medications used in clinical settings, the disadvantages of the commercially available products, and insight into the latest development strategies. For a more successful translation of such research into clinical practice, extensive knowledge of the chemical interactions between the components and a detailed understanding of the properties and mechanisms of biological matter are required. Moreover, the cost-efficiency of the surface treatment should be considered in the development process.

Update on drug interactions with non-vitamin-K-antagonist oral anticoagulants for stroke prevention in elderly patients

Introduction: We update the knowledge, since the last review in 2017, about drug-drug interactions (DDI) of non-vitamin-K-antagonist oral anticoagulants (NOAC) in patients ≥75 years.Areas covered: The literature was searched for: 'dabigatran,' 'rivaroxaban,' 'edoxaban,' or 'apixaban' and drugs, affecting platelet function, CYP3A4-, CYP2C9-, or P-Gp-activity. Pharmacodynamic DDI of NOAC with drugs affecting platelet function like nonsteroidal anti-inflammatory drugs and antiplatelet agents occur most frequently. Pharmacokinetic DDI with NOAC were found for 37 of 117 drugs. Reports about DDI with NOAC were found for 51% of P-gp-affecting, 38% for CYP2C9-affecting and 27% for CYP3A4-affecting drugs. Reports about DDI of cardiovascular drugs with NOAC were the most prevalent, followed by anti-infective and nervous system drugs. NOAC plasma levels were measured in retrospective and cohort studies and were associated with concomitant medication. Reports about DDI of NOAC were found in 71 patients ≥75 years.Expert opinion: The knowledge about DDI of NOAC in elderly patients is very limited. Studies should be carried out to investigate the role of drugs potentially interacting with NOAC, which until now have not been investigated. When studying DDI of NOAC, care should be taken to include elderly patients with impaired renal function and patients on polymedication.

Idarucizumab for Reversal of Dabigatran in Early/Emergency Surgeries: A Case Series

BACKGROUND

Idarucizumab is a humanized, monoclonal antibody fragment used specifically to reverse the anticoagulant effects of dabigatran.

CASE REPORTS

We discuss 4 cases of patients who were treated with idarucizumab to reverse dabigatran before early/emergency surgery. Two of the patients had subdural hematomas, 1 had a splenic laceration, and 1 had Fournier gangrene. All patients received 5 g of idarucizumab before surgery. Intraoperative blood loss in all patients was normal, no adverse events were reported, and the patients recovered normally. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The case reports presented provide detailed, practical, real-world experience beyond that reported in other case reports and the Reversal Effects of Idarucizumab on Active Dabigatran study. This can help guide clinicians on how idarucizumab can reverse the anticoagulant effect of dabigatran in emergency situations, including patients with subdural hematoma. Our experience suggests that idarucizumab may be a safe and effective antidote to the effects of dabigatran in real-life bleeding situations involving early or emergency surgeries.

The blood compatibility challenge. Part 1: Blood-contacting medical devices: The scope of the problem

Blood-contacting medical devices are an integral part of modern medicine. Such devices may be used for only a few hours or may be implanted for life. Despite advances in biomaterial science, clotting on medical devices remains a common problem. Systemic administration of antiplatelet drugs or anticoagulants is often needed to reduce the risk of clotting. Although effective, such therapy increases the risk of bleeding, which can be fatal. This chapter (a) describes some of the commonly used blood-contacting devices and their potential complications, (b) provides an overview of the mechanisms that drive device-associated clotting, and (c) reviews the strategies employed to attenuate clotting on blood-contacting medical devices. STATEMENT OF SIGNIFICANCE: This paper is part 1 of a series of 4 reviews discussing the problem of biomaterial associated thrombogenicity. The objective was to highlight features of broad agreement and provide commentary on those aspects of the problem that were subject to dispute. We hope that future investigators will update these reviews as new scholarship resolves the uncertainties of today.

Effects of Bemiparin Sodium Versus Dabigatran Etexilate After Anastomosis in Rat Carotid Arteries on the Development of Neointima and Thrombolytic Efficacy

BACKGROUND

Revascularization before infarct development after cerebral ischemia may affect morbidity. The success of revascularization can be less than expected because of spontaneous thrombosis or restenosis with intimal hyperplasia. The aim of this study was to compare dabigatran etexilate, a direct thrombin inhibitor, with bemiparin sodium, a second-generation low-molecular-weight heparin, after carotid artery anastomosis.

METHODS

This study used 24 randomly selected Sprague-Dawley rats. The rats were separated into 3 equal groups: group 1 (control group); group 2 (dabigatran group), in which dabigatran 10 mg/kg was orally administered for 7 days; and group 3 (bemiparin group), in which bemiparin 250 IU/kg was subcutaneously administered for 7 days. The right-side carotid artery of rats was used for anastomosis and the left-side carotid artery was used for the control. The carotid artery was explored and transected. Anastomosis was applied using 10/0 polypropylene sutures. After 7 days of treatment, the right and left carotid arteries were removed. Lumen diameter, lumen area, tunica media thickness, edema, vessel wall injury, intimal hyperplasia, thrombus, and inflammation were evaluated in tissue biopsy specimens.

RESULTS

Bemiparin used after anastomosis caused less thickening of tunica media and reduced intimal hyperplasia but did not decrease lumen diameter and area. Dabigatran increased edema and inflammation but did not prevent intimal hyperplasia.

CONCLUSIONS

Bemiparin reduced intimal hyperplasia and prevented thrombosis angiogenesis, but dabigatran did not prevent intimal hyperplasia, and its anticoagulation effect was more than the antithrombotic effect.

Use of Direct-Acting Oral Anticoagulants in Nonagenarians: A Call for More Data

The prevalence and embolic risk of atrial fibrillation (AF) increase with age. Vitamin K antagonists (VKAs) or direct-acting oral anticoagulants (DOACs) reduce the risk of stroke or embolism. The aim of this review was to summarize the paucity of information regarding the safety and efficacy of DOACs in AF patients aged 90 years or older. The maximum age of included patients is not listed in any of the available DOAC investigating trials and registries, thus it is unclear if nonagenarians were included. Additionally, we could not find any subgroup analysis addressing this issue. There is an urgent need to collect more information on the safety and efficacy of oral anticoagulants in nonagenarians, especially regarding the role of DOACs, which are increasingly prescribed to this group of patients despite the lack of data. The best solution to this problem would be a prospective, randomized trial in this group of patients, however that would require a large investment of time, effort, and funds. In the meantime, we suggest subgroup analyses addressing the effects and safety of VKAs versus DOACs in nonagenarians, in case they have been included in previously completed or ongoing trials or registries. This could be feasible and would be desirable in view of the large amount of data already accumulated. Irrespective of age, anemia in patients receiving DOACs should be carefully investigated to rule out occult blood loss. With their known interaction profile and the possibility of monitoring these drugs, VKAs should be favored over DOACs in nonagenarians until more data are available regarding the safety of DOACs.