Dabigatran etexilate: the first oral anticoagulant available in the United States since warfarin

Reinforcing our defense or weakening the enemy? A comparative overview of defensive and offensive strategies developed to confront COVID-19

Developing effective strategies to confront coronavirus disease 2019 (COVID-19) has become one of the greatest concerns of the scientific community. In addition to the vast number of global mortalities due to COVID-19, since its outbreak, almost every aspect of human lives has changed one way or another. In the present review, various defensive and offensive strategies developed to confront COVID-19 are illustrated. The Administration of immune-boosting micronutrients/agents, as well as the inhibition of the activity of incompetent gatekeepers, including some host cell receptors (e.g. ACE2) and proteases (e.g. TMPRSS2), are some efficient defensive strategies. Antibody/phage therapies and specifically vaccines also play a prominent role in the enhancement of host defense against COVID-19. Nanotechnology, however, can considerably weaken the virulence of SARS-CoV-2, utilizing fake cellular locks (compounds mimicking cell receptors) to block the viral keys (spike proteins). Generally, two strategies are developed to interfere with the binding of spike proteins to the host cell receptors, either utilizing fake cellular locks to block the viral keys or utilizing fake viral keys to block the cellular locks. Due to their evolutionary conserved nature, viral enzymes, including 3CLpro, PLpro, RdRp, and helicase are highly potential targets for drug repurposing strategy. Thus, various steps of viral replication/transcription can effectively be blocked by their inhibition, leading to the elimination of SARS-CoV-2. Moreover, RNA decoy and CRISPR technologies likely offer the best offensive strategies after viral entry into the host cells, inhibiting the viral replication/assembly in the infected cells and substantially reducing the quantity of viral progeny.

Algorithms for monitoring warfarin use: Results from Delphi Method

Warfarin stands as the most prescribed oral anticoagulant. New oral anticoagulants have been approved recently; however, their use is limited and the reversibility techniques of the anticoagulation effect are little known. Thus, our study's purpose was to develop algorithms for therapeutic monitoring of patients taking warfarin based on the opinion of physicians who prescribe this medicine in their clinical practice. The development of the algorithm was performed in two stages, namely: (i) literature review and (ii) algorithm evaluation by physicians using a Delphi Method. Based on the articles analyzed, two algorithms were developed: "Recommendations for the use of warfarin in anticoagulation therapy" and "Recommendations for the use of warfarin in anticoagulation therapy: dose adjustment and bleeding control." Later, these algorithms were analyzed by 19 medical doctors that responded to the invitation and agreed to participate in the study. Of these, 16 responded to the first round, 11 to the second and eight to the third round. A 70% consensus or higher was reached for most issues and at least 50% for six questions. We were able to develop algorithms to monitor the use of warfarin by physicians using a Delphi Method. The proposed method is inexpensive and involves the participation of specialists, and it has proved adequate for the intended purpose. Further studies are needed to validate these algorithms, enabling them to be used in clinical practice.

Distribution characteristics and factors influencing oral warfarin adherence in patients after heart valve replacement

PURPOSE

Oral warfarin anticoagulation is a long-term treatment that is required after heart valve replacement. This treatment can prevent serious complications, such as embolism, thereby increasing patients' postoperative survival rates and quality of life. Patients treated with artificial mechanical heart valve replacement were followed up over the phone at different times after the procedure, which is an effective method for preventing accidents related to postoperative oral warfarin anticoagulation. Our goal was to determine a method for providing theoretical guidance to patients on oral warfarin anticoagulation following heart valve replacement.

PATIENTS AND METHODS

The participants of this study were patients who received artificial mechanical heart valve replacements and were followed up for 2 years after the procedure. Patient adherence to medical advice was calculated, and the distribution characteristics of adherence to prescribed timing, prescribed dose, and regular clinical follow-up among patients of both sexes and of different ages, regions, and educational levels attained were compared.

RESULTS

Univariate and multifactorial logistic regression analyses were used to evaluate the factors influencing adherence. Our analyses showed that adherence to oral warfarin anticoagulation in patients after heart valve replacement is influenced by sex, age, residential location, and educational attainment. The medication habits of patients can be evaluated accordingly via phone follow-up. As such, dose adjustment recommendations can be provided, significantly increasing the adherence to oral warfarin anticoagulation in patients after heart valve replacement.

CONCLUSION

Adherence to oral warfarin anticoagulation among patients after heart valve replacement is affected by sex, age, type of residence, and educational level, as well as adherence to clinical follow-up over the phone. The follow-up sessions help establish good doctor-patient communication, which is critical for timely medication guidance, thus shortening medication administration delays and decreasing the overall length of therapy.

Ultrasound-guided fine-needle aspiration biopsy of thyroid nodules in patients taking novel oral anticoagulants

BACKGROUND

Ultrasound-guided fine-needle aspiration biopsy (USGFNAB) is the most accurate form of evaluation for thyroid nodules. Many patients with thyroid nodules who present for USGFNAB are on anticoagulant agents, including the novel oral anticoagulants (NOACs), for stroke prevention in atrial fibrillation or venous thrombosis prophylaxis.

SUMMARY

There has been at least one retrospective study describing neck USGFNAB bleeding risks in patients on antithrombotic and/or anticoagulant agents. This study concluded that there was no major bleeding risk or increase in hematoma formation in patients on antithrombotic or anticoagulant agents while undergoing USGFNAB, and there was no need to discontinue these agents prior to the procedure. With the emergence of NOACs, further recommendations should be made for patients on these agents who will be undergoing USGFNAB for thyroid nodules. Currently, there are no published studies regarding patients on NOACs who undergo USGFNAB.

CONCLUSIONS

It has previously been established that patients on historical anticoagulant agents do not need to discontinue therapy prior to minor procedures such as needle aspirations or dental procedures. Therefore, in patients currently taking dabigatran, rivaroxaban, or apixaban, it is concluded that it is reasonable and safe to continue the novel oral anticoagulant agents prior to USGFNAB of thyroid nodules without major risk of bleeding. This conclusion is based not only on the fact that minor procedures are considered safe in patients on NOACs, but also because patients on historical anticoagulant agents do not need to discontinue therapy prior to minor procedures.

Diagnosis and management of atrial fibrillation: an overview

Atrial fibrillation (AF) has been defined as the new cardiovascular "epidemic". Its prevalence is rising in developed countries, and the associated social and economic costs are high. In the last few years, there has been an increasing interest in understanding the mechanisms of AF and its management. New pharmacotherapies together with novel techniques for surgical and catheter treatment of AF have been developed, allowing the maintenance of sinus rhythm and the alleviation of symptoms in a large number of patients with AF. However, there are still some challenges that need to be addressed. This article gives an overview of the current state of the art on novel techniques for diagnosis and management of AF.

[Dabigatran: transforming the management of oral anticoagulation]

The utility of oral anticoagulation with warfarin in thromboembolic disease has been demonstrated for several decades, although these drugs have significant problems in terms of adequate control, interactions and risk of bleeding. In the last decade, new anticoagulants have emerged. The first was dabigatran with a demonstrated anticoagulant effect approaching the ideal anticoagulant profile. The view that dabigatran transforms oral anticoagulation therapy has arisen from the RE-VOLUTION program, with more than 34000 patients analyzed. This program has confirmed the value of oral anticoagulation with dabigatran compared with other anticoagulants; this drug eliminates all the drawbacks of warfarin, benefitting both patients and the healthcare system. The growth of the aging population has increased the number of risk situations in which anticoagulation is used. There is now a drug that meets the criteria for the ideal anticoagulant, transforming the management of oral anticoagulation. The findings demonstrated with dabigatran in prior studies are progressively being transferred to clinical practice. Following the usual development of new drugs, and according to the latest Laurence Desmond stages, results in agreement with those of previous studies are expected, namely, indisputable improvements in oral anticoagulation for patients and the health system.

Pathology consultation on monitoring direct thrombin inhibitors and overcoming their effects in bleeding patients

OBJECTIVES

Direct thrombin inhibitors (DTIs), a relatively new class of anticoagulants, present several challenges regarding monitoring of their anticoagulant effects and overcoming bleeding associated with their use. The aim of this article is to (1) briefly present the pharmacologic properties of currently available DTIs, (2) discuss approaches to laboratory assessment of these drugs, and (3) review management of bleeding associated with their use.

METHODS

Published literature on DTIs, including clinical trials, case reports, and experimental animal models, was reviewed. The primary authors also reviewed their first-hand experiences with DTI anticoagulation.

RESULTS

Based on the literature review and the practical experiences of the authors, suggestions for the monitoring of DTIs and algorithmic approaches for the management of DTI-associated bleeding were developed.

CONCLUSIONS

Routine coagulation assays (eg, the prothrombin time) show a relatively poor correlation with the degree of anticoagulation and DTI drug concentrations. Newer assays, such as the ecarin clotting time and dilute thrombin time, may be more useful in assessing DTI anticoagulation, but these assays are not yet widely available. Low-grade DTI-associated bleeds are best managed with cessation of the drug and supportive care, while higher-grade and/or life-threatening bleeds may best be reversed by active drug removal (eg, via the administration of activated charcoal or hemodialysis). At present there is little evidence to suggest that transfusion products such as factor concentrates or thawed plasma are of any particular benefit in DTI reversal; however, these products may play a supportive role in the management of bleeding.

A systematic update on the state of novel anticoagulants and a primer on reversal and bridging

BACKGROUND

Current prevention and treatment of venous thromboembolism (VTE) includes familiar agents that have been in use for many years, including unfractionated heparin, low-molecular-weight heparin (LMWH), and vitamin K antagonists (VKAs). A number of novel oral anticoagulants are currently developed or are in stages of development to either replace VKAs in concert with initial heparin or LMWH, or to replace both heparin/LMWH and VKAs totally as monotherapy. These agents hold the promise of not requiring monitoring, being safer in terms of bleeding risk than current agents, and being of equal or improved efficacy compared with established anticoagulants.

METHODS

In the following report, we systematically review the oral agents currently approved or closest to approval for both VTE and atrial fibrillation treatment, focusing on the treatment of VTE: dabigatran, rivaroxaban, and apixaban.

RESULTS

Findings of clinical use and comparisons to standard care of these agents are summarized in depth, by succinctly reviewing all major randomized controlled trials. Mechanistic and functional differences are reviewed, as Dabigatran targets activated factor II (factor IIa), while rivaroxaban and apixaban target activated factor X (factor Xa). We also discuss the inability at the present time to reliably reverse the anticoagulant effects of these agents, provide a suggested strategy for reversal, and finally discuss an approach to bridging these agents when other procedures are required while currently taking one of these three agents.

CONCLUSIONS

These agents, while still with many unanswered questions, demonstrate great promise in the prevention and treatment of VTE.

Dabigatran bleed risk with closed head injuries: are we prepared?

OBJECT

The direct thrombin inhibitor dabigatran has recently been approved in the US as an alternative to warfarin. The lack of guidelines, protocols, and an established specific antidote to reverse the anticoagulation effect of dabigatran potentially increases the rates of morbidity and mortality in patients with closed head injury (CHI). Confronted with this new problem, the authors reviewed their initial clinical experience.

METHODS

The authors retrospectively reviewed all cases of adult patients (age ≥ 18 years) who sustained CHI secondary to ground-level falls and who presented to the authors' provisional regional Level I trauma center between February 2011 and May 2011. The authors divided these patients into 3 groups based on anticoagulant therapy: dabigatran, warfarin, and no anticoagulants.

RESULTS

Between February 2011 and May 2011, CHIs from ground-level falls were sustained by 5 patients while on dabigatran, by 15 patients on warfarin, and by 25 patients who were not on anticoagulants. The treatment of the patients on dabigatran at the authors' institution had great diversity. Repeat CT scans obtained during reversal showed 4 of 5 patients with new or expanded hemorrhages in the dabigatran group, whereas the warfarin group had 3 of 15 (p = 0.03). The overall mortality rate for patients sustaining CHI on dabigatran was 2 (40%) of 5, whereas that of the warfarin group was 0 (0%) of 15 (p = 0.05).

CONCLUSIONS

It is critical for physicians involved in the care of patients with CHI on dabigatran to be aware of an elevated mortality rate if no treatment protocol or guideline is in place. The authors will soon implement a reversal management protocol for patients with CHI on dabigatran at their institution in an attempt to improve efficacy and safety in their treatment approach.

Confronting the chronically anticoagulated, acute care surgery patient as we evolve into the post-warfarin era

There are a growing number of new anticoagulants used as an alternative to warfarin. Surgeons will be confronted with an increasing number of patients who may be on these outpatient medications and must be familiar with their management strategies. The purpose of this review is to examine the mechanisms, monitoring and therapeutic reversal of the non-warfarin antithrombotic agents now so frequently confronting the acute care surgeon.

Management of venous thromboembolism in patients with advanced gastrointestinal cancers: what is the role of novel oral anticoagulants?

Venous thromboembolism (VTE) is a frequent complication of gastrointestinal cancers that increases morbidity and may impact mortality. Low-molecular-weight heparins (LMWHs) and vitamin K antagonists (VKAs) are standard anticoagulation options for the ambulatory gastrointestinal cancer patient with VTE, but both of these agents are challenging to use for various reasons. Novel oral anticoagulants (NOAs) are new, orally available anticoagulants designed to be easier to administer with more reliable pharmacokinetics that eliminate the need for frequent monitoring of various laboratory parameters. This paper reviews the existing efficacy and safety data for the use of NOAs dabigatran etexilate, rivaroxaban, and apixaban and discusses the potential role of these agents in the management of gastrointestinal cancer-related VTE.

Significant Bleeding in Elderly Patient with Atrial Fibrillation Due to Probable Interaction between Dabigatran and Amiodarone

Objective:

To present the case of an elderly patient who developed significant bleeding while receiving a standard dose of dabigatran with concomitant amiodarone therapy.

Case Summary:

A 77-year-old man was admitted for upper gastrointestinal bleeding that presented as coffee ground emesis. A coronary artery bypass graft had been performed 4 weeks earlier, which was well tolerated, except that his postoperative course was complicated by atrial fibrillation, for which amiodarone was initiated; dabigatran was added subsequently. Upon his admission to the hospital, dabigatran was stopped. The patient's bleeding was stabilized and dabigatran 150 mg twice daily was restarted after amiodarone was discontinued. The laboratory was not equipped to measure thrombin clotting time or ecarin clotting time; therefore, the team relied on the measurement of international normalized ratio (INR) and activated partial thromboplastin time to guide therapy based on pharmacokinetic and pharmacodynamic studies of therapeutic dabigatran concentrations. Based on laboratory values the following morning, the team maintained dabigatran 150 mg once daily. Subsequent INR and partial thromboplastin time values were within the desired range. He remained stable, without further evidence of bleeding even after anticoagulation with dabigatran was restarted for atrial fibrillation.

Discussion:

Dabigatran received FDA approval in October 2010 to reduce the risk of stroke and systemic embolization in patients with nonvalvular atrial fibrillation. It has a favorable monitoring profile compared to warfarin. The manufacturer acknowledges the potential for amiodarone to increase the effective concentration of dabigatran because of its inhibition of P-glycoprotein. An objective causality assessment using the Horn Drug Interaction Probability Scale revealed that the interaction was probable.

Conclusions:

A probable interaction suggests that providers should use caution with the coadministration of amiodarone with dabigatran; dose adjustment in the setting of concomitant administration in elderly patients with atrial fibrillation should be considered.

Novel Oral Anticoagulation in Management of Venous Thromboembolism, Atrial Fibrillation, and Acute Coronary Syndrome

Venous thromboembolism (VTE) is a major public health concern since the incidence of VTE rises substantially with age. Furthermore, the diagnosis can be elusive since patients can present differently, causing delay in diagnosis and initiation of treatment and resulting in major morbidity and mortality. In addition to accuracy and precision in diagnosis, antithrombotic therapies are the cornerstones of VTE management. In traditional paradigm, vitamin K antagonists (warfarin), indirect factor Xa inhibitors, and heparin are the foundation in management of VTE. Warfarin has been the only available oral anticoagulant therapy for several decades. Although warfarin is effective in both treatment and prophylaxis against VTE, there are several limitations. Therefore, the novel anticoagulation therapies, including rivaroxaban, apixaban, and dabigatran etexilate, have apparent advantages over warfarin in terms of clinical efficacy and adverse effects. The objective of this review is to describe the background and clinical implications of these novel anticoagulants.