Safety of new oral anticoagulant drugs: a perspective

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.

Nephrotic Syndrome – Different Risk of Venous Thromboembolism with Different Approaches to Justify Prophylactic Anticoagulation

All of the circumstances influencing any of the elements of Virchow’s Triad can increase the risk of venous thromboembolism. Assessing prothrombotic factors can sometimes be difficult. One of the examples of such a condition is nephrotic syndrome. In this condition at least two elements of Virchow’s triad are affected: physiological blood composition and the venous blood flow which is slowed down by the edema. Except for the cases mentioned in KDIGO (Kidney Disease: Improving Global Outcomes), the use of anticoagulant drugs in the prophylaxis of VTE (Venous Thromboembolism) in nephrotic syndrome seems unclear. Nevertheless, due to the increased risk of VTE, it is worth implementing mechanical anticoagulant prophylaxis, which can also improve the quality of life of patients by reducing swelling. The article analyzes the current knowledge on the field and gives some proposals with low bleeding risk.

Venous thromboembolic complications in patients with chronic kidney disease: prevalence and features of drug treatment

The article is an opinion on the problem of venous thromboembolic (VTE) complications in patients with chronic kidney disease (CKD), which is significant and urgent for Russia. Signs of CKD are noted in more than 1/3 of patients with chronic heart failure; a decrease in kidney function is observed in 36% of people over the age of 60, in people of working age, a decrease in function is noted in 16% of cases, and in the presence of cardiovascular diseases increases to 26%. Clinical research data convincingly show that CKD is an independent risk factor for the development of VTE complications. The last decade has given us the opportunity to observe a kind of "revolution" in VTE therapy, which is associated with the appearance on the market of direct oral anticoagulants, including inhibitors of factor IIa (thrombin) and factor Xa. These drugs are approved by the Food and Drug Administration for the treatment of acute thromboembolism. Nevertheless, patients with severe CKD (estimated glomerular filtration rate 30 ml/min) are still limited to the use of unfractionated heparin and vitamin K antagonists, as there is insufficient data to support the use of direct oral anticoagulants in this population.

New drug, new problem: do hip fracture patients taking NOACs experience delayed surgery, longer hospital stay, or poorer outcomes?

INTRODUCTION

Neck of femur fractures are common in the comorbid, often anticoagulated, elderly. Non-vitamin K antagonist oral anticoagulants (NOACs) may affect patient outcomes. We aimed to evaluate whether hip fracture patients admitted on warfarin or NOAC therapy were at risk of operative delay, prolonged length of stay, or increased mortality.

METHODS

We collected data for 845 patients admitted to our centre between October 2014 and December 2016. Multivariable linear regression analysis was performed to test the association between warfarin and NOAC therapy on time to surgery and length of stay. Variables in the regression model were age, sex, admission AMTS, pre-fracture mobility, ASA score, fracture type, and operation type. Fisher's exact test was used to evaluate whether warfarin or NOAC therapy delayed surgery beyond 36 or 48 hours, or decreased 30-day, 6-month, or 12-month survival.

RESULTS

Time to surgery was delayed in anticoagulated patients (p = 0.028). NOAC therapy was independently associated with increased time to surgery beyond 36 hours (p = 0.001), although not beyond 48 hours (p = 0.355), whereas warfarin therapy was not associated with either. Anticoagulation did not increase length of stay (p = 0.331). Warfarin therapy significantly reduced 30-day survival (p = 0.007), but NOAC therapy did not (p = 0.244). Neither warfarin nor NOAC therapy affected further survival.

CONCLUSIONS

NOAC therapy delays time to surgery beyond the NHS England 'Best Practice Tariff' in hip fracture patients. We aim to prospectively investigate long-term outcomes. Without a NOAC antidote, policy must change to ensure time-appropriate surgery for patients on NOACs. Preoperative involvement of the haematology team is essential.

Proximal femur fractures in patients taking anticoagulants

Thirty per cent of patients presenting with proximal femoral fractures are receiving anticoagulant treatment for various other medical reasons. This pharmacological effect may necessitate reversal prior to surgical intervention to avoid interference with anaesthesia or excessive peri/post-operative bleeding. Consequently, delay to surgery usually occurs.

Platelet inhibitors (aspirin, clopidogrel) either alone or combined do not need to be discontinued to allow acute hip surgery. Platelet transfusions can be useful but are rarely needed.

Vitamin K antagonists (VKA, e.g. warfarin) should be reversed in a timely fashion and according to established readily accessible departmental protocols. Intravenous vitamin K on admission facilitates reliable reversal, and platelet complex concentrate (PCC) should be reserved for extreme scenarios.

Direct oral anticoagulants (DOAC) must be discontinued prior to hip fracture surgery but the length of time depends on renal function ranging traditionally from two to four days.

Recent evidence suggests that early surgery (within 48 hours) can be safe. No bridging therapy is generally recommended.

There is an urgent need for development of new commonly available antidotes for every DOAC as well as high-level evidence exploring DOAC effects in the acute hip fracture surgical setting.

Cite this article: EFORT Open Rev 2020;5:699-706. DOI: 10.1302/2058-5241.5.190071

Pulmonary embolism: update on management and controversies

Pulmonary embolism is a common and potentially fatal cardiovascular disorder that must be promptly diagnosed and treated. The diagnosis, risk assessment, and management of pulmonary embolism have evolved with a better understanding of efficient use of diagnostic and therapeutic options. The use of either clinical probability adjusted or age adjusted D-dimer interpretation has led to a reduction in diagnostic imaging to exclude pulmonary embolism. Direct oral anticoagulation therapies are safe, effective, and convenient treatments for most patients with acute venous thromboembolism, with a lower risk of bleeding than vitamin K antagonists. These oral therapeutic options have opened up opportunities for safe outpatient management of pulmonary embolism in selected patients. Recent clinical trials exploring the use of systemic thrombolysis in intermediate to high risk pulmonary embolism suggest that this therapy should be reserved for patients with evidence of hemodynamic compromise. The role of low dose systemic or catheter directed thrombolysis in other patient subgroups is uncertain. After a diagnosis of pulmonary embolism, all patients should be assessed for risk of recurrent venous thromboembolism to guide duration of anticoagulation. Patients with a venous thromboembolism associated with a strong, transient, provoking risk factor can safely discontinue anticoagulation after three months of treatment. Patients with an ongoing strong risk factor, such as cancer, or unprovoked events are at increased risk of recurrent events and should be considered for extended treatment. The use of a risk prediction score can help to identify patients with unprovoked venous thromboembolism who can benefit from extended duration therapy. Despite major advances in the management of pulmonary embolism, up to half of patients report chronic functional limitations. Such patients should be screened for chronic thromboembolic pulmonary hypertension, but only a small proportion will have this as the explanation of their symptoms. In the remaining patients, future studies are needed to understand the pathophysiology and explore interventions to improve quality of life.

A Systematic Review of Prophylactic Anticoagulation in Nephrotic Syndrome

Introduction

Nephrotic syndrome is associated with an increased risk of venous and arterial thromboembolism, which can be as high as 40% depending on the severity and underlying cause of nephrotic syndrome. The 2012 Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend prophylactic anticoagulation only in idiopathic membranous nephropathy but acknowledge that existing data are limited and of low quality. There is a need for better identification of vulnerable patients in order to balance the risks of anticoagulation.

Methods

We undertook a systematic search of the topic in MEDLINE, EMBASE and COCHRANE databases, for relevant articles between 1990 and 2019.

Results

A total of 2381 articles were screened, with 51 full-text articles reviewed. In all, 28 articles were included in the final review.

Conclusion

We discuss the key questions of whom to anticoagulate, when to anticoagulate, and how to prophylactically anticoagulate adults with nephrotic syndrome. Using available evidence, we expand upon current KDIGO guidelines and construct a clinical algorithm to aid decision making for prophylactic anticoagulation in nephrotic syndrome.

Safety of cataract surgery in patients treated with the new oral anticoagulants (NOACs)

PURPOSE

To evaluate the safety of phacoemulsification of cataract in patients taking new oral anticoagulants (NOACs).

METHODS

In a prospective case series, consecutive patients on NOACs (dabigatran, rivaroxaban, or apixaban) who were referred for uncomplicated cataract surgery to the eye institute underwent a thorough ophthalmological and hematological evaluation. Rivaroxaban and apixaban anti-factor Xa tests, and diluted thrombin time for dabigatran, were used for monitoring anticoagulation levels in blood. Blood was drawn for these tests just prior to surgery and at a peak level of the drug at about 4 h post-surgery (2 h after the drug was given). All surgeries were videotaped and patients were examined at 1 and 7 days after the operation. The main outcome measures included assessment of intra-operative, postoperative ocular bleeding, and other related complications.

RESULTS

Thirty-five eyes of 25 unrelated patients ranging in age from 63 to 92 years (mean 77.6 years) underwent phacoemulsification. Intra-operative bleeding was observed in 5 eyes from the conjunctiva or limbus at the main incision site. No intraocular bleeding occurred. No hemorrhagic complications were observed during the 1-week follow-up. According to anti-factor Xa levels prior to surgery and following surgery, 85% of the patients were on therapeutic levels of NOACs.

CONCLUSIONS

Clear corneal incision phacoemulsification performed under topical anesthesia can be safely performed in simple cases of cataract without discontinuing NOAC treatment.

Accurate GFR in obesity-protocol for a systematic review

BACKGROUND

Obesity is increasing globally. Chronic kidney disease (CKD) is strongly associated with obesity. Kidney function is commonly estimated with equations using creatinine (such as CKD-EPI equation) which is a product of muscle metabolism. Decisions about categorizing CKD, planning modality of renal replacement therapies, and adjusting dosages of medications excreted by the kidneys are done using these equations. However, it is not well appreciated that creatinine-based equations may not accurately estimate kidney function in obese individuals. We plan a systematic review of diagnostic studies which will compare estimating equations to actual measured kidney function.

METHODS

We will systematically search electronic bibliographic databases including MEDLINE, EMBASE, and the Cochrane Library with no restrictions on language or specific dates. The search terms will be adapted for the different databases using a combination of Medical Subject Heading and relevant keywords contained in titles and abstracts. Our preliminary search strategy using Cochrane, MEDLINE, and EMBASE databases have identified 190, 1246, and 1660 citations, respectively. For all studies selected, we will extract information on general study characteristics, study participant (age, sex, ethnicity, weight, height, BMI, BSA), type and protocol of reference standard utilized, the index test studied, the methodology of measurement of index test, categories of GFR, the proportion of eGFR within 10, 20, 30, 40, and 50% of measured GFR, and bias between eGFR and measured GFR. If the quality of methods and risk of bias are adequate, we will perform a meta-analysis. We will assess the heterogeneity using the χ 2 and the I 2 statistics to examine whether the estimates from studies included could be pooled. Sensitivity and multivariate meta-regression analyses will be performed to assess the effects of clinical factors and socio-demographic characteristics reported in included studies on the meta-analytic estimates. All analysis will be performed using the Comprehensive Meta-analysis software.

DISCUSSION

This systematic review might help to inform clinicians on the best equation to use in patients with obesity and CKD for staging of CKD and for medication dosing. If no equation is deemed suitable, this review will form a basis for future studies of GFR in obese individuals.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018104345.

It's time for head-to-head trials with direct oral anticoagulants

Direct oral anticoagulants (DOACs) have become the recommended first choice anticoagulant agent for treatment of acute venous thromboembolism (VTE) in non-cancer patients and are increasingly prescribed worldwide. They have not only intrinsic advantages, such as rapid onset of action and wide therapeutic windows, but also a lower risk of major, intracranial and fatal bleeding in VTE patients compared to vitamin K antagonists. Even though DOACs are often referred to as uniform drug class, there is growing evidence that each DOAC has a specific risk profile. Indirect comparisons and retrospective cohort studies suggest that apixaban may be associated with a lower risk of major bleeding than other DOACs, but there are no head-to-head trials with DOACs. Therefore, current guidelines do not recommend one DOAC over another and the choice of a specific DOAC is mainly based on physician and patient preferences, reimbursement and availability. Retrospective cohort studies and VTE registries are important to identify potential differences in efficacy and safety between DOACs; but they are methodologically too limited to inform the optimal choice of oral anticoagulant agent. Randomized controlled trials are crucial to inform sound treatment recommendations, because proper randomization is the key to unprejudiced treatment allocation and minimization of unmeasured and unknown confounding. Given increasing evidence of differences in safety profiles of DOACs from indirect comparisons and observational studies, it's time for head-to-head trials with DOACs.

Reversible covalent direct thrombin inhibitors

INTRODUCTION

In recent years, the traditional treatments for thrombotic diseases, heparin and warfarin, are increasingly being replaced by novel oral anticoagulants offering convenient dosing regimens, more predictable anticoagulant responses, and less frequent monitoring. However, these drugs can be contraindicated for some patients and, in particular, their bleeding liability remains high.

METHODS

We have developed a new class of direct thrombin inhibitors (VE-DTIs) and have utilized kinetics, biochemical, and X-ray structural studies to characterize the mechanism of action and in vitro pharmacology of an exemplary compound from this class, Compound 1.

RESULTS

We demonstrate that Compound 1, an exemplary VE-DTI, acts through reversible covalent inhibition. Compound 1 inhibits thrombin by transiently acylating the active site S195 with high potency and significant selectivity over other trypsin-like serine proteases. The compound inhibits the binding of a peptide substrate with both clot-bound and free thrombin with nanomolar potency. Compound 1 is a low micromolar inhibitor of thrombin activity against endogenous substrates such as fibrinogen and a nanomolar inhibitor of the activation of protein C and thrombin-activatable fibrinolysis inhibitor. In the thrombin generation assay, Compound 1 inhibits thrombin generation with low micromolar potency but does not increase the lag time for thrombin formation. In addition, Compound 1 showed weak inhibition of clotting in PT and aPTT assays consistent with its distinctive profile in the thrombin generation assay.

CONCLUSION

Compound 1, while maintaining strong potency comparable to the current DTIs, has a distinct mechanism of action which produces a differentiating pharmacological profile. Acting through reversible covalent inhibition, these direct thrombin inhibitors could lead to new anticoagulants with better combined efficacy and bleeding profiles.

Evidence based diagnosis and management of chronic subdural hematoma: A review of the literature

Chronic subdural hematomas are encapsulated blood collections within the dural border cells with characteristic outer "neomembranes". Affected patients are more often male and typically above the age of 70. Imaging shows crescentic layering of fluid in the subdural space on a non-contrast computed tomography (CT) scan, best appreciated on sagittal or coronal reformats. Initial medical management involves reversing anticoagulant/antiplatelet therapies, and often initiation of anti-epileptic drugs (AEDs). Operative interventions, such as twist-drill craniostomy (TDC), burr-hole craniostomy (BHC), and craniotomy are indicated if imaging implies compression (maximum fluid collection thickness >1 cm) or the patient is symptomatic. The effectiveness of various surgical techniques remains poorly characterized, with sparse level 1 evidence, variable outcome measures, and various surgical techniques. Postoperatively, subdural drains can decrease recurrence and sequential compression devices can decrease embolic complications, while measures such as early mobilization and re-initiation of anticoagulation need further study. Non-operative management, including steroid therapy, etizolam, tranexamic acid, and angiotensin converting enzyme inhibitors (ACEI) also remain poorly studied. Recurrent hemorrhages are a major complication affecting around 10-20% of patients, and therefore close follow-up is essential.

Medication Reviews by a Clinical Pharmacist at an Irish University Teaching Hospital

Purpose: Pharmacist-led medication reviews in hospitals have shown improvement in patient outcomes. The aim of this study is to describe the prevalence and nature of pharmacist interventions (PIs) following a medication review in an Irish teaching hospital. Methods: PIs were recorded over a six-month period in 2015. PIs were assessed by a panel of healthcare professionals (n = 5) to estimate the potential of adverse drug events (ADEs). Descriptive statistics were used for the variables and the chi square test for independence was used to analyse for any association between the variables. Results: Of the 1216 patients (55.8% female; median age 68 years (interquartile range 24 years)) who received a medication review, 313 interventions were identified in 213 patients. 412 medicines were associated with PIs, of which drugs for obstructive airway disease (n = 82), analgesics (n = 56), and antibacterial products for systemic use (n = 50) were the most prevalent. A statistically significant association was found between PI and patient’s age ≥65 years (p = 0.000), as well as female gender (p = 0.037). A total of 60.7% of the PIs had a medium or high likelihood of causing an ADE. Conclusion: Pharmacist-led medication review in a hospital setting prevented ADEs. Patients ≥65 years of age and female patients benefited the most from the interventions.

Dabigatran reversal with idarucizumab in a patient undergoing heart transplantation: first European report

Background

Dabigatran is a direct thrombin inhibitor with a favorable effectiveness and safety profile when compared to vitamin K antagonists, both in randomized trials and real world registries of atrial fibrillation patients. Yet, physicians’ fear of high bleeding risk scenarios in daily clinical practice still precludes a more widespread use of oral anticoagulation. We hereby report a successful case of dabigatran reversal with the novel monoclonal antibody fragment idarucizumab in a patient undergoing heart transplantation.

Case presentation

A 45-year old male patient on dabigatran for atrial fibrillation thromboprophylaxis was enlisted for heart transplantation due to end-stage ischemic heart failure. Upon donor availability and suitability and following the last intake of the drug 12 h previously, activated partial thromboplastin time was measured and found to be elevated. After general anesthesia and before extracorporeal circulation, idarucizumab was administered as two boluses of 2.5 g. Orthotopic heart transplantation ensued under full heparinization and cardiopulmonary bypass. Total chest tube output was 1125 mL after 3 days and 4 units of fresh frozen plasma and one platelet pool were administered in the operating room without further need for blood products. The post-operative period was uneventful.

Conclusions

Idarucizumab was associated with an effective hemostasis in the setting of heart transplantation. Dabigatran may be considered as an alternative to vitamin K antagonists in heart transplant candidates with an indication for oral anticoagulation.

First Reported Case of Hemopericardium Related to Dabigatran Use Reversed by New Antidote Idarucizumab

Dabigatran, the first novel oral anticoagulant (NOAC) with a reversal agent, heralded a paradigm shift in the treatment of nonvalvular atrial fibrillation. The potential for life-threatening hemorrhagic events with the use of NOACs has been highly debated since the effectiveness of reversal agents such as idarucizumab is based primarily on pharmacologic data. It is known that cancer patients are at an increased risk of bleeding with anticoagulation, though specific studies demonstrating the risks or efficacy of NOACs in this population are lacking. We provide the first report of hemopericardium resulting in multiorgan failure related to dabigatran use that was successfully reversed by idarucizumab in a man with prostate cancer on chemotherapy.

e-Health-based management of patients receiving oral anticoagulation therapy: results from the observational thrombEVAL study

Essentials e-Health based health care by an expert centre may advance management of oral anticoagulation. Outcome of patients was compared between an e-health based coagulation service and regular care. Patients in the coagulation service cohort experienced a significantly better clinical outcome. Lower risk for adverse events was related to anticoagulation-specific and non-specific outcome.

SUMMARY

Background Management of oral anticoagulation (OAC) therapy is essential to minimize adverse events in patients receiving vitamin K-antagonists (VKAs). Data on the effect of e-health-based anticoagulation management systems on the clinical outcome of OAC patients are limited. Objectives To compare the clinical outcome of OAC patients managed by an e-health-based coagulation service (CS) with that of patients receiving regular medical care (RMC). Methods The prospective multicenter cohort study thrombEVAL (NCT01809015) comprised 1558 individuals receiving RMC and 760 individuals managed by a CS. Independent study monitoring and adjudication of endpoints by an independent review panel were implemented. Results The primary study endpoint (composite of thromboembolism, clinically relevant bleeding and death) occurred in 15.7 per 100 patient-years (py) with RMC and in 7.0 per 100 py with the CS (rate ratio [RR], 2.3; 95% confidence interval [CI], 1.7-3.1). Rates for major and clinically relevant bleeding were higher with RMC than with the CS: 6.8 vs. 2.6 and 10.1 vs. 3.6 per 100 py, respectively. Thromboembolic events showed an RR of 1.5 (95% CI, 0.8-2.6) comparing RMC with the CS. Hospitalization (RR, 2.6; 95% CI, 2.3-3.0) and all-cause mortality (RR, 4.6; 95% CI, 2.8-7.7) were markedly more frequent with RMC. In Cox regression analysis with adjustment for age, sex, cardiovascular risk factors, comorbidities, treatment characteristics and sociodemographic status, hazard ratios (HR) for the primary endpoint (HR, 2.2; 95% CI, 1.5-3.4), clinically relevant bleeding (HR, 3.1; 95% CI, 1.7-5.5), hospitalization (HR, 2.2; 95% CI, 1.8-2.8) and all-cause mortality (HR, 5.6; 95% CI, 2.9-11.0) favored CS treatment. Conclusions In this study, e-health-based management of OAC therapy was associated with a lower frequency of OAC-specific and non-specific adverse events.

Net clinical benefit of dabigatran vs. warfarin in venous thromboembolism: analyses from RE-COVER®, RE-COVER™ II, and RE-MEDY™

The direct oral anticoagulants, e.g., dabigatran etexilate (DE), are effective and well tolerated treatments for venous thromboembolism (VTE). Net clinical benefit (NCB) is a useful concept in weighing potential benefits against potential harm of comparator drugs. The NCB of DE vs. warfarin in VTE treatment was compared. Post-hoc analyses were performed on pooled data from the 6-month RE-COVER® and RE-COVER™ II trials, and data from the RE-MEDY™ trial (up to 36 months), to compare the NCB of DE (150 mg twice daily) and warfarin [target international normalized ratio (INR) 2.0–3.0]. Patients (≥18 years old) had symptomatic proximal deep vein thrombosis and/or pulmonary embolism. NCB was the composite of cardiovascular endpoints (non-fatal events of recurrent VTE, myocardial infarction, stroke or systemic embolism), all-cause death, and bleeding outcomes, all weighted equally. A broad definition of NCB included major bleeding events (MBE) and clinically relevant non-major bleeding events as bleeding outcomes, while a narrow definition included just MBE. The pooled dataset totalled 5107 patients from RE-COVER/RE-COVER II and 2856 patients from RE-MEDY. When NCB was narrowly defined, NCB was similar between DE and warfarin. When broadly defined, NCB was superior with DE vs. warfarin [RE-COVER/RE-COVER II, hazard ratio (HR) 0.80; 95% confidence interval (CI), 0.68–0.95 and RE-MEDY, HR 0.73; 95% CI 0.59–0.91]. These findings were unaffected by warfarin time in therapeutic range. The NCB of DE was similar or superior to warfarin, depending on the NCB definition used, regardless of the quality of INR control.

Perioperative Considerations and Management of Patients Receiving Anticoagulants

Anticoagulants remain the primary strategy for the prevention and treatment of thrombosis. Unfractionated heparin, low molecular weight heparin (LMWH), fondaparinux, and warfarin have been studied and employed extensively with direct thrombin inhibitors typically reserved for patients with complications or those requiring interventions. Novel oral anticoagulants have emerged from clinical development and are expected to replace older agents with their ease to use and more favorable pharmacodynamic profiles. Increasingly, anesthesiologists are being requested to anesthetize patients who are on some form of anticoagulants and hence it is important to have sound understanding of pharmacology, dosing, monitoring, and toxicity of anticoagulants. We searched the online databases including PubMed Central, Cochrane, and Google Scholar using anticoagulants, perioperative management, anesthetic considerations, and LMWH as keywords for the articles published between 1994 and 2015 while writing this review. In this article, we will review the different classes of anticoagulants and how to manage them in the perioperative settings.

Efficacy of prothrombin complex concentrates for the emergency reversal of dabigatran-induced anticoagulation

Dabigatran is effective in decreasing the risk of ischaemic stroke in patients with atrial fibrillation. However, like all anticoagulants, it is associated with a risk of bleeding. In cases of trauma or emergency surgery, emergency reversal of dabigatran-induced anticoagulation may be required. A specific reversal agent for dabigatran, idarucizumab, has been approved by the US Food and Drug Administration. Alternative reversal agents are available, such as prothrombin complex concentrates (PCCs) and activated PCCs (aPCCs). In this review we evaluate the role of PCCs and aPCCs in the reversal of dabigatran anticoagulation and consider which tests are appropriate for monitoring coagulation in this setting. Pre-clinical studies, small clinical studies and case reports indicate that PCCs and aPCCs may be able to reverse dabigatran-induced anticoagulation in a dose-dependent manner. However, dosing based on coagulation parameters can be difficult because available assays may not provide adequate sensitivity and specificity for measuring anticoagulation induced by dabigatran or the countering effects of PCCs/aPCCs. In addition, PCCs or aPCCs can potentially provoke thromboembolic complications. Despite these limitations and the fact that PCCs and aPCCs are not yet licensed for dabigatran reversal, their use appears to be warranted in patients with life-threatening haemorrhage if idarucizumab is not available.

Management of novel oral anticoagulants in emergency and trauma surgery

BACKGROUND

The compelling safety, efficacy and predictable effect of novel oral anticoagulants (NOACs) is driving a rapid expansion in their therapeutic indications. Management of the increasing number of patients on those new agents in the setting of emergency or trauma surgery can be challenging and the absence of specific reversal agents has been a matter of concern. This review summarises the key principles that underpin the management of those patients with a particular emphasis on the recent development of specific antidotes.

FINDINGS

As of 2015, a new line of antidotes, specific for these drugs, are at different stages of their development with their release imminent. However, as NOACs are innately reversible due to their short half-life, the use of reversal agents will probably be restricted to a few exceptional cases. Post-marketing surveillance will be paramount to better clarify the role of these promising drugs.

CONCLUSIONS

Management of patients on NOACs in the context of emergency or trauma surgery relies on best supportive care in combination with the blood products and/or specific antidotes as required. Familiarity with the new reversal agents is essential but further evidence on their indications, safety and efficacy as well as consensus guidelines are warranted prior to widespread adoption.

Protein engineering: a new frontier for biological therapeutics

Protein engineering holds the potential to transform the metabolic drug landscape through the development of smart, stimulusresponsive drug systems. Protein therapeutics are a rapidly expanding segment of Food and Drug Administration approved drugs that will improve clinical outcomes over the long run. Engineering of protein therapeutics is still in its infancy, but recent general advances in protein engineering capabilities are being leveraged to yield improved control over both pharmacokinetics and pharmacodynamics. Stimulus- responsive protein therapeutics are drugs which have been designed to be metabolized under targeted conditions. Protein engineering is being utilized to develop tailored smart therapeutics with biochemical logic. This review focuses on applications of targeted drug neutralization, stimulus-responsive engineered protein prodrugs, and emerging multicomponent smart drug systems (e.g., antibody-drug conjugates, responsive engineered zymogens, prospective biochemical logic smart drug systems, drug buffers, and network medicine applications).

Comparative pharmacokinetics of the main compounds of Shanzhuyu extract after oral administration in normal and chronic kidney disease rats

ETHNOPHARMACOLOGICAL RELEVANCE

Pharmacokinetic studies on traditional Chinese medicine are useful to evaluate and predict the drug efficacy and safety. The renal impairment may affect drug clearance and other pharmacokinetic processes which can increase toxicity and drug to drug interactions or cause ineffective therapy. Pharmacokinetic studies in pathological status rats might be meaningful for revealing the action mechanism and improving clinical medication of the herb medicine.

MATERIALS AND METHODS

A highly sensitive and rapid ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) method with multiple-reaction monitoring (MRM) mode was developed and validated for simultaneous quantitation of morroniside and loganin in normal and doxorubicin-induced chronic kidney disease (CKD) rat plasma after oral administration of Shanzhuyu (fruit of Cornus officinalis) extract.

RESULTS

Both calibration curves gave satisfactory linearity (r>0.99) at linear range of 1.96-1962.5ngmL(-1) for morroniside, 1.53-1531.25ngmL(-1) for loganin. The precision and accuracy of the in vivo study were assessed by intra-day and inter-day assays. The percentages of relative standard deviation (RSD) were all within 9.58% and the accuracy (RE) was in the -6.02% to 8.11% range. The extraction recoveries of morroniside, loganin and internal standard (IS) were all >67.62% and the matrix effects ranged from 95.07% to 102.75%.

CONCLUSIONS

The pharmacokinetic behavior of morroniside and loganin in normal and CKD rat plasma was determined in this paper. The significant different pharmacokinetic parameters might partly result from the changes of P-glycoprotein and metabolic enzymes in the pathological state. The pharmacokinetic research in the pathological state might provide more useful information to guide the clinical usage of the herb medicine.

Neuraxial and peripheral nerve blocks in patients taking anticoagulant or thromboprophylactic drugs: challenges and solutions

Incidence of hemorrhagic complications from neuraxial blockade is unknown, but classically cited as 1 in 150,000 epidurals and 1 in 220,000 spinals. However, recent literature and epidemiologic data suggest that for certain patient populations the frequency is higher (1 in 3,000). Due to safety concerns of bleeding risk, guidelines and recommendations have been designed to reduce patient morbidity/mortality during regional anesthesia. Data from evidence-based reviews, clinical series and case reports, collaborative experience of experts, and pharmacology used in developing consensus statements are unable to address all patient comorbidities and are not able to guarantee specific outcomes. No laboratory model identifies patients at risk, and rarity of neuraxial hematoma defies prospective randomized study so “patient-specific” factors and “surgery-related” issues should be considered to improve patient-oriented outcomes. Details of advanced age, older females, trauma patients, spinal cord and vertebral column abnormalities, organ function compromise, presence of underlying coagulopathy, traumatic or difficult needle placement, as well as indwelling catheter(s) during anticoagulation pose risks for significant bleeding. Therefore, balancing between thromboembolism, bleeding risk, and introduction of more potent antithrombotic medications in combination with regional anesthesia has resulted in a need for more than “consensus statements” to safely manage regional interventions during anticoagulant/thromboprophylactic therapy.

Dabigatran for the prevention and treatment of thromboembolic disorders

Dabigatran, an oral direct thrombin inhibitor, was the first of a new class of drugs referred to as non-vitamin K oral anticoagulants. Dabigatran is better than warfarin for stroke prevention in non-valvular atrial fibrillation (dose of 150 mg twice a day), non-inferior to enoxaparin for venous thromboembolism prevention after orthopedic surgery and non-inferior to warfarin in preventing recurrence after acute venous thromboembolism. The safety profile is similar to standard anticoagulants, with significant reduction observed in intracranial hemorrhage. Other advantages include a rapid onset of action and a predictable pharmacokinetic profile, allowing a fixed-dose regimen without the need for routine anticoagulation monitoring. In the event of bleeding, general support measures are recommended and if severe, the use of non-specific hemostatic agents such as prothrombin complex concentrates and recombinant factor VIIa must be considered. A specific reversal agent (idarucizumab) is in development.

Determination of Apixaban Levels in Human Plasma by a High-Throughput Liquid Chromatographic Tandem Mass Spectrometry Assay / Determinarea rapidă a apixabanului în plasma umană prin cromatografie de lichide de înaltă performanță cuplată cu spectrometrie de masă în tandem

A high-throughput liquid chromatography method with detection by tandem mass spectrometry (LC-MS/MS) was developed and validated for the quantification of apixaban in human plasma. The separation was performed on a Gemini-NX column under isocratic conditions using a 33:67 (v/v) mixture of acetonitrile and 1 mM ammonium formate in water at 40 ºC with a flow rate of 0.5 mL/min. The detection of apixaban was performed in multiple reaction monitoring mode (m/z 417.2 from m/z 460.2) with electrospray positive ionization. A single-step protein precipitation with methanol was used for plasma sample preparation. The method was validated with respect to selectivity, linearity (r > 0.994), intra-day and inter-day precision (CV < 14.4 %) and accuracy (bias < 9.5 %) over the range of 9.70 - 970.00 ng/mL plasma. The lower limit of quantification (LLOQ) was 9.70 ng/mL and the recovery was between 97.4 - 104.5 %. The method is fast, efficient, requires the processing of a small volume of plasma (50 μL), a short run-time (1 min) for chromatographic analysis, and a simple and rapid preparation of samples. It is very well suited for clinical therapeutic drug monitoring and pharmacokinetic studies.