Argatroban for therapeutic anticoagulation for heparin resistance associated with Covid-19 infection

Highlights in TMPRSS2 inhibition mechanism with guanidine derivatives approved drugs for COVID-19 treatment

Transmembrane protease serine 2 (TMPRSS2) has been identified as a critical key for the entry of coronaviruses into human cells by cleaving and activating the spike protein of SARS-CoV-2. To block the TMPRSS2 function, 18 approved drugs, containing the guanidine group were tested against TMPRSS2's ectodomain (7MEQ). Among these drugs, Famotidine, Argatroban, Guanadrel and Guanethidine strongly binds with TMPRSS2 S1 pocket with estimated Fullfitness energies of -1847.12, -1630.87, -1605.81 and -1600.52 kcal/mol, respectively. A significant number of non-covalent interactions such as hydrogen bonding, hydrophobic and electrostatic interactions were detected in protein-ligand complexes. In addition, the ADMET analysis revealed a perfect concurrence with the aptitude of these drugs to be developed as an anti-SARS-CoV-2 therapeutics. Further, MD simulation and binding free energy calculations were performed to evaluate the dynamic behavior and stability of protein-ligand complexes. The results obtained herein highlight the enhanced stability and good binding affinities of the Argatroban and Famotidine towards the target protein, hence might act as new scaffolds for TMPRSS2 inhibition.Communicated by Ramaswamy H. Sarma.

Serial thrombin generation and exploration of alternative anticoagulants in critically ill COVID-19 patients: Observations from Maastricht Intensive Care COVID Cohort

Background

COVID-19 associated coagulopathy (CAC) is associated with an increase in thromboembolic events. Current guidelines recommend prophylactic heparins in the management of CAC. However, the efficacy of this strategy in the intensive care population remains uncertain.

Objective

We aimed to measure thrombin generation (TG) to assess CAC in intensive care unit (ICU) patients receiving thromboprophylaxis with low molecular weight heparin (LMWH) or unfractionated heparin (UFH). In addition, we performed statistical modeling to link TG parameters to patient characteristics and clinical parameters. Lastly, we studied the potency of different anticoagulants as an alternative to LMWH treatment in ex vivo COVID-19 plasma.

Patients/Methods

We included 33 patients with confirmed COVID-19 admitted at the ICU. TG was measured at least twice over the course of 6 weeks after admission. Thrombin generation parameters peak height and endogenous thrombin potential (ETP) were compared to healthy controls. Results were subsequently correlated with a patient characteristics and laboratory measurements. In vitro spiking in TG with rivaroxaban, dabigatran, argatroban and orgaran was performed and compared to LMWH.

Results

Anti-Xa levels of all patients remained within the therapeutic range throughout follow-up. At baseline, the mean (SE) endogenous thrombin potential (ETP) was 1,727 (170) nM min and 1,620 (460) nM min for ellagic acid (EA) and tissue factor (TF), respectively. In line with this we found a mean (SE) peak height of 353 (45) nM and 264 (96) nM for EA and TF. Although fluctuating across the weeks of follow-up, TG parameters remained elevated despite thromboprophylaxis. In vitro comparison of LMWHs and direct thrombin inhibitors (e.g., agratroban, dabigatran) revealed a higher efficacy in reducing coagulation potential for direct thrombin inhibition in both ellagic acid (EA) and tissue factor (TF) triggered TG.

Conclusion

In a sub-group of mechanically ventilated, critically ill COVID-19 patients, despite apparent adequate anti-coagulation doses evaluated by anti-Xa levels, thrombin generation potential remained high during ICU admission independent of age, sex, body mass index, APACHE II score, cardiovascular disease, and smoking status. These observations could, only partially, be explained by (anti)coagulation and thrombosis, inflammation, and multi-organ failure. Our in vitro data suggested that direct thrombin inhibition compared with LMWH might offer an alternate, more effective anticoagulant strategy in COVID-19.

Use of the CytoSorb® filter for elimination of residual therapeutic argatroban concentrations during heparinized cardiopulmonary bypass for heart transplantation

INTRODUCTION

No antidote or established extracorporeal elimination strategy is available for argatroban. Hemadsorption facilitates elimination of smaller drugs.

CASE REPORT

A 34-year-old patient underwent urgent heart transplantation. Because of a history of heparin-induced thrombocytopenia, preoperative anticoagulation was performed with argatroban. Despite ceasing of the continuous infusion of argatroban 2 h before surgery, concentration only declined from 0.60 μg/ml to 0.58 μg/ml before surgery, and the activated clotting time (ACT) value shortly was 223 s. Microvascular bleeding had been observed when starting surgery. A CytoSorb® absorption column was integrated into the system of the heparin-anticoagulated cardiopulmonary bypass (CPB) circuit and a flow of 400 mL/min provided during the 2 h of extracorporeal circulation. The argatroban concentration after weaning from CPB was 0.04 μg/ml and satisfying hemostasis had been achieved after protamine administration.

CONCLUSION

Data indicate that the CytoSorb® absorption column might be an effective tool for quick extracorporeal removal of therapeutic concentrations of argatroban.

From ancient leech to direct thrombin inhibitors and beyond: New from old

Medicinal leeches have been used in health care since before written history, with widely varying popularity over the centuries. Nowadays, medicinal leech therapy is mainly used in plastic and reconstructive microsurgery, with new interesting potential therapeutic applications in many other diseases. The leech's best-known salivary product, hirudin - one of the most powerful natural anticoagulants - was the only remedy to prevent blood clotting until the discovery of heparin. Starting from hirudin, pharmacological research succeeded in developing new anticoagulants, which represent a cornerstone of prevention and treatment of thromboembolic disease. While we are perhaps on the threshold of a new era of anticoagulation, with the development of FXI and XII inhibitors and direct reversible covalent thrombin inhibitors, which promise to achieve effective anticoagulation without bleeding risk. This review retraces the intriguing journey of these drugs in cardiovascular disease, highlighting the fil rouge that links the ancient leech to the current and oncoming antithrombotic therapy. We think that knowledge of the past is key to understanding and appreciating the present and to seize future opportunities.

[Anticoagulation in coronavirus disease 2019 (COVID-19): confirmed and controversial aspects]

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is associated with a high risk of microvascular immunothrombosis as well as symptomatic and incidental thromboembolisms, predominantly in the venous system but also in the arterial system. This explains among other things the high cardiovascular morbidity and mortality of the patients. The present state of knowledge on the pathophysiology of immunothrombosis and the strategies of anticoagulation in patients with coronavirus disease 2019 (COVID-19) are summarized and illuminated in this article. According to the current guidelines moderately to severely ill patients who are being treated in hospital should receive thrombosis prophylaxis with low molecular weight or unfractionated heparin or alternatively with fondaparinux, as long as there is no clearly increased risk of bleeding. Apart from the established indications for treatment, an intensified or therapeutic dose prophylaxis should be considered very cautiously in these critically ill patients, also due to the increased bleeding complications. The routine continuation of prophylactic anticoagulation after discharge from hospital is currently not recommended.

Caution in Using the Activated Partial Thromboplastin Time to Monitor Argatroban in COVID-19 and Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT)

Introduction

Argatroban is licensed for patients with heparin-induced thrombocytopenia and is conventionally monitored by activated partial thromboplastin time (APTT) ratio. The target range is 1.5 to 3.0 times the patients’ baseline APTT and not exceeding 100 s, however this baseline is not always known. APTT is known to plateau at higher levels of argatroban, and is influenced by coagulopathies, lupus anticoagulant and raised FVIII levels. It has been used as a treatment for COVID-19 and Vaccine-induced Immune Thrombocytopenia and Thrombosis (VITT). Some recent publications have favored the use of anti-IIa methods to determine the plasma drug concentration of argatroban.

Methods

Plasma of 60 samples from 3 COVID-19 patients and 54 samples from 5 VITT patients were tested by APTT ratio and anti-IIa method (dilute thrombin time dTT). Actin FS APTT ratios were derived from the baseline APTT of the patient and the mean normal APTT.

Results

Mean APTT ratio derived from baseline was 1.71 (COVID-19), 1.33 (VITT) compared to APTT ratio by mean normal 1.65 (COVID-19), 1.48 (VITT). dTT mean concentration was 0.64 µg/ml (COVID-19) 0.53 µg/ml (VITT) with poor correlations to COVID-19 baseline APTT ratio r² = 0.1526 p <0.0001, mean normal r² = 0.2188 p < 0.0001; VITT baseline APTT ratio r² = 0.04 p < 0.001, VITT mean normal r² = 0.0064 p < 0.001.

Conclusions

We believe that dTT is a superior method to monitor the concentration of argatroban, we have demonstrated significant differences between APTT ratios and dTT levels, which could have clinical impact. This is especially so in COVID-19 and VITT.

A Case of COVID-19 Related Coagulopathy Complications and Heparin Resistance

Mechanisms of COVID-19 coagulopathy have been speculated and are not definitively understood; the current speculation is that there is elaborate crosstalk between the inflammatory and hemostatic systems which contributes to the overall increased thrombotic risk in the setting of COVID-19 resulting in a hypercoagulable state. A few documented reports regarding cases of apparent heparin resistance in patients with COVID-19 with complications of thromboembolic events occurring in the setting of heparin anticoagulation have been described. This phenomenon of heparin resistance has been observed in patients with active, severe COVID-19 infection. However, we describe a unique case of a patient who had recovered from a recent, mild COVID-19 infection that did not require hospitalization and presented with acute limb ischemia and demonstrated heparin resistance. The patient was managed by specialists in vascular surgery, intensivists, cardiologists, hematology, and physical medicine and rehabilitation (PMR). We present the case of a patient who had successfully recovered from COVID-19 yet demonstrated post-COVID-19 complications related to coagulopathy and heparin resistance. 

[Anticoagulation in intensive care medicine]

Kritisch kranke Patienten sind in hohem Maße durch Störungen der Hämostase gefährdet, diese können sowohl mit einer verstärkten Blutungsneigung als auch mit einem erhöhten Risiko für thromboembolische Ereignisse einhergehen. Bei akuten vaskulären Ereignissen ist die spezifische Therapie mit medikamentöser Antikoagulation bzw. Plättchenaggregationshemmung essenziell, bei Patienten mit Vorerkrankungen ist die angepasste Fortführung einer vorbestehenden Antikoagulation während intensivmedizinischer Behandlung von Bedeutung, des Weiteren sind sowohl medikamentöse Thromboseprophylaxe als auch die Frage nach potenziell therapeutischen Optionen, wie Antikoagulanzien bei Sepsis und infektionsgetriggerten Störungen der Blutgerinnung, im klinischen Alltag wichtig. Spezifische Fragestellungen ergeben sich bei der Anwendung extrakorporaler Maßnahmen wie Nierenersatzverfahren sowie Kreislaufunterstützungs- und Ersatzverfahren. In den letzten Jahren sind eine Reihe neuer Präparate zur Antikoagulation und Plättchenhemmung verfügbar geworden. Die Therapiekontrolle über labordiagnostische Verfahren stellt einen zentralen Punkt dar. In dieser Übersichtsarbeit werden aktuelle Aspekte zu diesen Themen praxisnah aufgeführt.

Viscoelastic testing reveals normalization of the coagulation profile 12 weeks after severe COVID-19

COVID 19 is associated with a hypercoagulable state and frequent thromboembolic complications. For how long this acquired abnormality lasts potentially requiring preventive measures, such as anticoagulation remains to be delineated. We used viscoelastic rotational thrombelastometry (ROTEM) in a single center cohort of 13 critical ill patients and performed follow up examinations three months after discharge from ICU. We found clear signs of a hypercoagulable state due to severe hypofibrinolysis and a high rate of thromboembolic complications during the phase of acute illness. Three month follow up revealed normalization of the initial coagulation abnormality and no evidence of venous thrombosis in all thirteen patients. In our cohort the coagulation profile was completely normalized three months after COVID-19. Based on these findings, discontinuation of anticoagulation can be discussed in patients with complete venous reperfusion.

[S2k Guideline - Recommendations for Inpatient Therapy of Patients with COVID-19]

Since December 2019, the novel coronavirus SARS-CoV-2 (Severe Acute Respiratory Syndrome - Corona Virus-2) has been spreading rapidly in the sense of a global pandemic. This poses significant challenges for clinicians and hospitals and is placing unprecedented strain on the healthcare systems of many countries. The majority of patients with Coronavirus Disease 2019 (COVID-19) present with only mild symptoms such as cough and fever. However, about 6 % require hospitalization. Early clarification of whether inpatient and, if necessary, intensive care treatment is medically appropriate and desired by the patient is of particular importance in the pandemic. Acute hypoxemic respiratory insufficiency with dyspnea and high respiratory rate (> 30/min) usually leads to admission to the intensive care unit. Often, bilateral pulmonary infiltrates/consolidations or even pulmonary emboli are already found on imaging. As the disease progresses, some of these patients develop acute respiratory distress syndrome (ARDS). Mortality reduction of available drug therapy in severe COVID-19 disease has only been demonstrated for dexamethasone in randomized controlled trials. The main goal of supportive therapy is to ensure adequate oxygenation. In this regard, invasive ventilation and repeated prone positioning are important elements in the treatment of severely hypoxemic COVID-19 patients. Strict adherence to basic hygiene, including hand hygiene, and the correct wearing of adequate personal protective equipment are essential when handling patients. Medically necessary actions on patients that could result in aerosol formation should be performed with extreme care and preparation.