Argatroban anticoagulation in critically ill patients

In vitro Effect of Dalteparin and Argatroban on Hemostasis in Critically Ill Sepsis Patients with New-Onset Thrombocytopenia

Thrombocytopenia is common among critically ill sepsis patients, while they also hold an increased risk for thromboembolic events. Thus, the choice of anticoagulant prophylaxis for this patient population is challenging. We investigated the in vitro effect of low-molecular-weight heparin (dalteparin) and direct thrombin inhibitor (argatroban) on the hemostasis in blood from sepsis patients with new-onset thrombocytopenia. Thrombocytopenia was defined as a platelet count drop of ≥30% and/or from >100 × 10 ⁹ /L to 30 to 100 × 10 ⁹ /L within 24 hours prior to inclusion. We included five healthy individuals and ten patients. Analyses of thrombin generation (Calibrated Automated Thrombogram), thrombin-antithrombin (TAT) complex levels, prothrombin fragment 1+2 (F1+2), and rotational thromboelastometry (ROTEM) were performed. Based on dose-response relationships investigated in healthy blood, patient samples were spiked with prophylactic (0.25 IU/mL) and therapeutic (0.75 IU/mL) dalteparin and low (0.25 µg/mL) and high (0.50 µg/mL) argatroban concentrations, each with a sample without anticoagulant. In patients, the endogenous thrombin potential was markedly lower in therapeutic dalteparin samples than in samples without anticoagulant [median (range): 29 (0-388) vs. 795 (98-2121) nM × min]. In high argatroban concentration samples, thrombin lag time was longer than in samples without anticoagulant [median (range): 15.5 (10.5-20.2) versus 5.3 (2.8-7.3) min]. Dalteparin and argatroban both increased clotting time but did not affect maximum clot firmness in the ROTEM INTEM assay. Six patients had elevated TAT and eight patients had elevated F1 + 2. In conclusion, dalteparin mainly affected the amount of thrombin generated and argatroban delayed clot initiation in critically ill sepsis patients with new-onset thrombocytopenia. Neither anticoagulant affected clot strength.

Anticoagulation Management during Extracorporeal Membrane Oxygenation-A Mini-Review

Extracorporeal membrane oxygenation (ECMO) has been established as a life-saving technique for patients with the most severe forms of respiratory or cardiac failure. It can, however, be associated with severe complications. Anticoagulation therapy is required to prevent ECMO circuit thrombosis. It is, however, associated with an increased risk of hemocoagulation disorders. Thus, safe anticoagulation is a cornerstone of ECMO therapy. The most frequently used anticoagulant is unfractionated heparin, which can, however, cause significant adverse effects. Novel drugs (e.g., argatroban and bivalirudin) may be superior to heparin in the better predictability of their effects, functioning independently of antithrombin, inhibiting thrombin bound to fibrin, and eliminating heparin-induced thrombocytopenia. It is also necessary to keep in mind that hemocoagulation tests are not specific, and their results, used for setting up the dosage, can be biased by many factors. The knowledge of the advantages and disadvantages of particular drugs, limitations of particular tests, and individualization are cornerstones of prevention against critical events, such as life-threatening bleeding or acute oxygenator failure followed by life-threatening hypoxemia and hemodynamic deterioration. This paper describes the effects of anticoagulant drugs used in ECMO and their monitoring, highlighting specific conditions and factors that might influence coagulation and anticoagulation measurements.

Thromboprophylaxis with argatroban in critically ill patients with sepsis: a review

During sepsis, an initial prothrombotic shift takes place, in which coagulatory acute-phase proteins are increased, while anticoagulatory factors and platelet count decrease. Further on, the fibrinolytic system becomes impaired, which contributes to disease severity. At a later stage in sepsis, coagulation factors may become depleted, and sepsis patients may shift into a hypo-coagulable state with an increased bleeding risk. During the pro-coagulatory shift, critically ill patients have an increased thrombosis risk that ranges from developing micro-thromboses that impair organ function to life-threatening thromboembolic events. Here, thrombin plays a key role in coagulation as well as in inflammation. For thromboprophylaxis, low molecular weight heparins (LMWH) and unfractionated heparins (UFHs) are recommended. Nevertheless, there are conditions such as heparin resistance or heparin-induced thrombocytopenia (HIT), wherein heparin becomes ineffective or even puts the patient at an increased prothrombotic risk. In these cases, argatroban, a direct thrombin inhibitor (DTI), might be a potential alternative anticoagulatory strategy. Yet, caution is advised with regard to dosing of argatroban especially in sepsis. Therefore, the starting dose of argatroban is recommended to be low and should be titrated to the targeted anticoagulation level and be closely monitored in the further course of treatment. The authors of this review recommend using DTIs such as argatroban as an alternative anticoagulant in critically ill patients suffering from sepsis or COVID-19 with suspected or confirmed HIT, HIT-like conditions, impaired fibrinolysis, in patients on extracorporeal circuits and patients with heparin resistance, when closely monitored.

Hemostatic Management in Extracorporeal Membrane Oxygenation

The use of extracorporeal membrane oxygenation (ECMO) for acute cardiac and/or respiratory failure has grown exponentially in the past several decades. Systemic anticoagulation is a fundamental element of caring for ECMO patients. Hemostatic management during ECMO walks a fine line to balance the risk of safe and effective anticoagulant delivery to mitigate thromboembolic complications and minimizing hemorrhagic sequelae. This review discusses the pharmacology, monitoring parameters, and special considerations for anticoagulation in patients requiring ECMO.

Superior outcomes with Argatroban for heparin-induced thrombocytopenia: a Bayesian network meta-analysis

Background Argatroban, lepirudin, desirudin, bivalirudin, and danaparoid are commonly used to manage heparin-induced thrombocytopenia related complications. However, the most suitable drug for this condition still remains controversial. Aim of the review This Bayesian network meta-analysis study compared the most common anticoagulant drugs used in the management of heparin-induced thrombocytopenia. Method All clinical trials comparing two or more anticoagulant therapies for suspected or confirmed heparin-induced thrombocytopenia were considered for inclusion. Studies concerning the use of heparins or oral anticoagulants were not considered. Data concerning hospitalisation length, thromboembolic, major, and minor haemorrhagic events, and mortality rate were collected. The network analyses were made through the STATA routine for Bayesian hierarchical random-effects model analysis with standardised mean difference (SMD) and log odd ratio (LOR) effect measures. Results Data from a total of 4338 patients were analysed. The overall mean age was 62.31 ± 6.6 years old. Hospitalization length was considerably shorter in favour of the argatroban group (SMD: − 1.70). Argatroban evidenced the lowest rate of major (LOR: − 1.51) and minor (LOR: − 0.57) haemorrhagic events. Argatroban demonstrated the lowest rate of thromboembolic events (LOR: 0.62), and mortality rate (LOR: − 1.16). Conclusion Argatroban performed better overall for selected patients with HIT. Argatroban demonstrated the shortest hospitalization, and lowest rate of haemorrhages, thromboembolisms, and mortality compared to bivalirudin, lepirudin, desirudin, and danaparoid.

Evaluation of direct thrombin inhibitors during a critical heparin shortage

A recent heparin shortage related to an outbreak of African Swine Flu in China led to substantial increase in the use of direct thrombin inhibitors (DTI) as an alternative. We evaluated the safety and efficacy of DTIs by assessing the anticoagulation assays within the initial 48 h of therapy comparing before and during shortage. A retrospective evaluation of bivalirudin and argatroban was conducted at a single center before (May 24, 2018 through August 25, 2019) and during heparin shortage (August 26, 2019 through February 20, 2020). The primary outcome was time to first therapeutic activated partial thromboplastin time (aPTT). Secondary outcomes included the percentage of time in therapeutic aPTT range, in-hospital mortality, incidence of recurrent thrombosis, and hemorrhagic events. Of the 204 patients included in the study, 95 patients [bivalirudin (n = 35), argatroban (n = 60)] were included in the pre-shortage cohort and 109 patients [bivalirudin (n = 68), argatroban (n = 41)] were during shortage. No significant difference was observed in the time to first therapeutic aPTT pre- and during shortage (8.9 h ± 10.8 vs 8.8 h ± 10.2, P = 0.62). Compared to pre-shortage cohort, a greater percentage of time was spent in therapeutic aPTT range within the initial 48 h (32% (0-50) vs. 41.6% (0-63), P = 0.04) during shortage without statistically significant differences in the rates of in-hospital mortality, thrombosis, or bleeding. While the optimal DTI protocol is still be determined, the protocols presented in this study allowed for wide-spread utilization of DTIs during a critical heparin shortage without compromising patient safety and effectiveness, likely reflective of the enhancement of DTI protocols, clinician education, and multidisciplinary collaboration and guidance from pharmacy and hematology.

Prognostic factors for patients with heparin-induced thrombocytopenia: a systematic review

Background  Little is known with regards to the prognostic factors for patients with suspected or diagnosed Heparin-Induced Thromobocytopenia (HIT). The role of patient and therapy characteristics may play a role in predicting the outcome. Aim of the review To investigate the role of patient and therapy characteristics as potential prognostic factors for HIT-related complications (haemorrhagic and thromboembolic events), and mortality. Method The present systematic review was conducted according to the PRISMA statement. In September 2020, the main online databases were accessed: Pubmed, EMBASE, Scopus, Google Scholar. All the clinical trials concerning the management of patients with suspected or confirmed HIT were eligible. Studies evaluating the use of oral anticoagulants (e.g. vitamin K antagonists, Apixaban) were not considered, along with those comparing the use of heparin. For pairwise correlation, the Pearson Product-Moment Correlation Coefficient (r) was used. The final effect was evaluated according to the Cauchy-Schwarz inequality.Results Data from 33 clinical studies (4338 patients) were retrieved. The overall mean age was 62.3 ± 6.6 years old. Patients with HIT-related thromboembolism at the moment of diagnosis were associated with greater rate of haemorrhages (P > 0.0001), thromboembolism (P > 0.0001) and mortality (P = 0.001). Patients with more comorbidities at diagnosis were associated with a greater risk of haemorrhages (P = 0.07), thromboembolism (P = 0.002) and mortality (P = 0.002). Patients with longer duration of the therapy were associated with lower rate of mortality (P = 0.04). ConclusionsPatient comorbidities, presence of HIT-related thromboembolism on admission and shorter anticoagulant therapy were found to be negative prognostic factors. Thrombocythemia on admission, patients age and gender did not influence the overall outcome.

Efficiency and safety evaluation of prophylaxes for venous thrombosis after gynecological surgery

BACKGROUND

In this study, we investigate the incidence of venous thrombosis (VT), and evaluate the effectiveness and safety of 3 major thromboprophylaxes and the potential risk factors for VT in women undergoing surgery for a gynecological malignancy.

METHODS

We performed a randomized controlled trial of 307 patients undergoing laparoscopic surgery for gynecological malignancies at a single institution from January 2016 to October 2017. Patients were divided into 3 groups: one receiving a half dose of low-molecular-weight heparin sodium injection (FLUXUM, Alfa Wassermann, Italy) delivered by injection, one receiving a full dose of FLUXUM, and a third group receiving an Argatroban injection.

RESULTS

None of the patients in our study developed a pulmonary embolism, bleeding, or infectious complications. There were no statistical differences in the rate of deep venous thrombosis (DVT) (0%, 0%, and 2.38%) and the superficial venous thromboembolism (SVT) (15.66%, 8.97%, and 18.6%) among the 3 groups. None of the patients developed symptomatic VT. The effect of treatment on alanine aminotransferase and aspartate aminotransferase differed between the groups, with a minimal effect in the Argatroban group, and all 3 methods resulted in minimal impairment of renal function. Decreased hemoglobin, elevated levels of D-dimer, and prothrombin time were closely related to thrombogenesis.

CONCLUSION

In conclusion, the incidence of postoperative thrombosis in gynecological malignancy among these Chinese people is not as low as we had originally presumed. Argatroban is not more effective than Parnaparin as a direct thrombin inhibitor, but it has less influence on liver function, which is beneficial for patients undergoing chemotherapy. Hemoglobin, D-dimer, and prothrombin time may be used to predict or detect thrombogenesis.

A Prospective Pilot Trial to Assess the Efficacy of Argatroban (Argatra®) in Critically Ill Patients with Heparin Resistance

The current study aims to evaluate whether prophylactic anticoagulation using argatroban or an increased dose of unfractionated heparin (UFH) is effective in achieving the targeted activated partial thromboplastin time (aPTT) of more than 45 s in critically ill heparin-resistant (HR) patients. Patients were randomized either to continue receiving an increased dose of UFH, or to be treated with argatroban. The endpoints were defined as achieving an aPTT target of more than 45 s at 7 h and 24 h. This clinical trial was registered on clinicaltrials.gov (NCT01734252) and on EudraCT (2012-000487-23). A total of 42 patients, 20 patients in the heparin and 22 in the argatroban group, were included. Of the patients with continued heparin treatment 55% achieved the target aPTT at 7 h, while only 40% of this group maintained the target aPTT after 24 h. Of the argatroban group 59% reached the target aPTT at 7 h, while at 24 h 86% of these patients maintained the targeted aPTT. Treatment success at 7 h did not differ between the groups (p = 0.1000), whereas at 24 h argatroban showed significantly greater efficacy (p = 0.0021) than did heparin. Argatroban also worked better in maintaining adequate anticoagulation in the further course of the study. There was no significant difference in the occurrence of bleeding or thromboembolic complications between the treatment groups. In the case of heparin-resistant critically ill patients, argatroban showed greater efficacy than did an increased dose of heparin in achieving adequate anticoagulation at 24 h and in maintaining the targeted aPTT goal throughout the treatment phase.

When Pigs Fly: A Multidisciplinary Approach to Navigating a Critical Heparin Shortage

A recent outbreak of African swine fever (ASF) in China has claimed the lives of millions of pigs, and although this virus has no health impacts on humans, the disruption of the global pig population has far-reaching negative impacts on economic and pork-derived products, including the creation of the critical drug heparin. The active pharmaceutical ingredient in heparin is derived from pig intestines, and because of the ASF outbreak, the U.S. faces an imminent shortage of heparin. This drug shortage has the potential for profound implications, as heparin is used in a substantial and varied number of medical conditions. In response to notification of the heparin shortage crisis, our institution, Massachusetts General Hospital, activated its Hospital Incident Command System to streamline organization of major stakeholders and oversee operational and clinical activities required to mitigate the potential risks and optimize alternative effective strategies. This article describes the essential elements of our institution's emergency response plan, including detailed clinical algorithms developed by our experts for maximal heparin conservation and waste reduction by promoting safe and effective alternative strategies. Through this practice, we have also identified opportunities to change providers' prescribing and utilization behaviors for the better. As the ASF has not yet been contained and this crisis continues, the strategies and policies employed by our institution can provide a framework for other institutions to tackle this ongoing challenge and future drug shortage crises. IMPLICATIONS FOR PRACTICE: A detailed description of how one institution addressed the current heparin crisis, to support heparin conservation and waste reduction, is provided. The strategies used helped decrease heparin use by 80% in less than 2 months of establishing the task force. This accomplishment can be credited to the development of a task force and strategic plan in which experts and stakeholders were quickly identified, offered a part in the decision-making process, and frequently updated. Furthermore, the response system was dynamic, accessible, and one in which challenges were recognized and acted upon. The key to any crisis management is respect for one another and constant and open communication. Heparin is such a widespread drug that this shortage can potentially affect every patient population and provider. Understanding one's institutional needs and the effect of this crisis on those needs is one of the first steps when developing a strategic plan. Continually evaluating and adjusting that approach in response to the needs of the institution are critical to its success. Moreover, as it did for the authors' institution, a constant appraisal of the strategies can lead to opportunities for improvements in organization and practice that can be sustained well beyond the crisis.

Anticoagulation with direct thrombin inhibitors during extracorporeal membrane oxygenation

Use of extracorporeal membrane oxygenation to support patients with critical cardiorespiratory illness is increasing. Systemic anticoagulation is an essential element in the care of extracorporeal membrane oxygenation patients. While unfractionated heparin is the most commonly used agent, unfractionated heparin is associated with several unique complications that can be catastrophic in critically ill patients, including heparin-induced thrombocytopenia and acquired antithrombin deficiency. These complications can result in thrombotic events and subtherapeutic anticoagulation. Direct thrombin inhibitors (DTIs) are emerging as alternative anticoagulants in patients supported by extracorporeal membrane oxygenation. Increasing evidence supports DTIs use as safe and effective in extracorporeal membrane oxygenation patients with and without heparin-induced thrombocytopenia. This review outlines the pharmacology, dosing strategies and available protocols, monitoring parameters, and special use considerations for all available DTIs in extracorporeal membrane oxygenation patients. The advantages and disadvantages of DTIs in extracorporeal membrane oxygenation relative to unfractionated heparin will be described.

Assessment of an Extended Interval Fondaparinux Dosing Regimen for Venous Thromboembolism Prophylaxis in Critically Ill Patients with Severe Renal Dysfunction Using Antifactor Xa Levels

OBJECTIVE

Pharmacologic options for venous thromboembolism (VTE) prophylaxis are often limited in critically ill patients due to thrombocytopenia and multisystem organ dysfunction. Fondaparinux offers potential advantages in the critically ill; however, it is currently contraindicated in severe renal dysfunction (SRD). We evaluated anti-factor Xa levels in critically ill patients with SRD who were receiving an extended interval dosing regimen of fondaparinux for VTE prophylaxis.

METHODS

A prospective, single-arm, interventional study was conducted at two academic hospitals of the Detroit Medical Center. Eligible patients were in the intensive care unit, had an estimated creatinine clearance of less than 30 ml/minute, and had either acute kidney injury or end-stage renal disease; several patients were taking renal replacement therapy. Fondaparinux was administered at an extended interval dosing regimen of 2.5 mg subcutaneously every 48 hours. Fondaparinux peak and trough anti-factor Xa levels were obtained. Lower extremity venous duplex studies were performed at baseline and study completion to assess for deep vein thrombosis (DVT), and patients were monitored for bleeding complications.

RESULTS

Thirty-two patients were enrolled. Patients received a median of four doses (interquartile range two to five) of fondaparinux. Fondaparinux peak (n=98) and trough (n=86) anti-factor Xa levels were 0.36 ± 0.18 mg/L and 0.17 ± 0.11 mg/L (mean ± SD), respectively, and were similar to levels reported in patients with normal renal function receiving conventional once-daily dosing. No lower extremity DVTs or suspected VTE events occurred. Two (6%) patients had significant bleeding events.

CONCLUSIONS

In critically ill patients with SRD, an extended interval fondaparinux dosing regimen of 2.5 mg every 48 hours for VTE prophylaxis achieved peak and trough anti-factor Xa levels similar to those reported in noncritically ill patients with normal renal function receiving once-daily fondaparinux. This regimen offers an alternative for patients with SRD when heparinoids must be avoided.

Monitoring of argatroban and lepirudin anticoagulation in critically ill patients by conventional laboratory parameters and rotational thromboelastometry - a prospectively controlled randomized double-blind clinical trial

Background

Argatroban or lepirudin anticoagulation therapy in patients with heparin induced thrombocytopenia (HIT) or HIT suspect is typically monitored using the activated partial thromboplastin time (aPTT). Although aPTT correlates well with plasma levels of argatroban and lepirudin in healthy volunteers, it might not be the method of choice in critically ill patients. However, in-vivo data is lacking for this patient population.

Therefore, we studied in vivo whether ROTEM or global clotting times would provide an alternative for monitoring the anticoagulant intensity effects in critically ill patients.

Methods

This study was part of the double-blind randomized trial “Argatroban versus Lepirudin in critically ill patients (ALicia)”, which compared critically ill patients treated with argatroban or lepirudin. Following institutional review board approval and written informed consent, for this sub-study blood of 35 critically ill patients was analysed. Before as well as 12, 24, 48 and 72 h after initiation of argatroban or lepirudin infusion, blood was analysed for aPTT, aPTT ratios, thrombin time (TT), INTEM CT,INTEM CT ratios, EXTEM CT, EXTEM CT ratios and maximum clot firmness (MCF) and correlated with the corresponding plasma concentrations of the direct thrombin inhibitor.

Results

To reach a target aPTT of 1.5 to 2 times baseline, median [IQR] plasma concentrations of 0.35 [0.01–1.2] μg/ml argatroban and 0.17 [0.1–0.32] μg/ml lepirudin were required. For both drugs, there was no significant correlation between aPTT and aPTT ratios and plasma concentrations. INTEM CT, INTEM CT ratios, EXTEM CT, EXTEM CT ratios, TT and TT ratios correlated significantly with plasma concentrations of both drugs. Additionally, agreement between argatroban plasma levels and EXTEM CT and EXTEM CT ratios were superior to agreement between argatroban plasma levels and aPTT in the Bland Altman analysis. MCF remained unchanged during therapy with both drugs.

Conclusion

In critically ill patients, TT and ROTEM parameters may provide better correlation to argatroban and lepirudin plasma concentrations than aPTT.

Trial registration

ClinicalTrials.gov, NCT00798525, registered on 25 Nov 2008

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0475-y) contains supplementary material, which is available to authorized users.

Argatroban pharmacokinetics and pharmacodynamics in critically ill cardiac surgical patients with suspected heparin-induced thrombocytopenia

Only limited data are available on the pharmacokinetic and pharmacodynamic properties of argatroban in critically ill patients under clinical conditions. We determined plasma concentrations of argatroban, and its main metabolite M1, within a time period of 48 hours in 25 critically ill cardiac surgical patients, who were suspected of heparininduced thrombocytopenia and had the clinical need for anticoagulation. Argatroban infusion was started at 0.5 µg/kg/minute, and adjusted in 0.1–0.25 µg/kg/minute increments when the activated partial thromboplastin time (aPTT) was not within the target range. Median argatroban plasma half-life was 2.7 hours (interquartile range 1.8 to 7.3). Linear regression analysis revealed that argatroban half-life was significantly related to the total bilirubin concentration (R2 = 0.66, p< 0.001), as well as to the metabolism of argatroban, which was assessed by the ratio of the areas under the concentration time curves (AUC) of argatroban and M1 (R2 = 0.60, p< 0.001). Continuous veno-venous haemodialysis did not significantly affect argatroban plasma half-life. The predictive property of argatroban plasma levels for aPTT was low (R2 = 0.28, p< 0.001). Multiple linear regression analysis revealed significant contributions of age and serum albumin levels to the effect of argatroban on aPTT, expressed as the AUC ratio argatroban/aPTT (R2 = 0.67, adjusted R2 = 0.65, p< 0.001). In conclusion, argatroban plasma half-life is markedly increased in critically ill cardiac surgical patients, and further prolonged by hepatic dysfunction due to impaired metabolism. Patient age and serum albumin concentration significantly contribute to the variability in the anticoagulant activity of argatroban.

Early initiation of argatroban therapy in the management of acute superior mesenteric venous thrombosis

Acute superior mesenteric venous thrombosis (ASMVT) is an intractable disease with poor prognosis. Argatroban, a direct thrombin inhibitor, may be a novel anticoagulant method in the therapy of ASMVT. The aim of the present study was to assess the efficacy and safety of early argatroban therapy in ASMVT patients. The current retrospective study reviewed a consecutive series of ASMVT patients receiving early argatroban therapy during hospitalization between March 2013 and April 2014, with 18 ASMVT patients included in the study. Of these, 16 patients without hepatic dysfunction underwent anticoagulant therapy with argatroban with a mean dose of 1.57±0.34 µg/kg/min and a mean duration of 12.2±3.7 days, while their activated partial thromboplastin time (aPTT) was elevated to 1.95±0.26 times the baseline value. In addition, 2 hepatic dysfunction patients received therapy with a dose of 0.41 µg/kg/min and 0.46 µg/kg/min, and with aPTT of 1.68 and 1.62 times the baseline value, respectively. Overall, 94% (n=17) of the patients presented clinical improvement, while 88% (n=16) of patients presented partially or completely dissolved thrombus in contrast-enhanced computed tomography images. The incidence of surgery and bowel resection was 6% (excluding 1 case with intestinal necrosis detected on admission). Furthermore, 11% (n=2) of patients experienced a bleeding episode, however no major bleeding or mortality occurred during hospitalization. During the follow-up, the mortality and the recurrence rate were 6% and 11%, respectively. In conclusion, early initiation of argatroban treatment may be an effective and safe therapy in ASMVT, manifesting efficient resolution of the thrombus, rapid improvement of symptoms, low incidence of bowel resection and bleeding complication, and low mortality rate.

[Heparin-induced thrombocytopenia type II (HIT II) : A medical-economic view]

BACKGROUND

In the context of inpatient and increasingly ambulatory thrombosis prophylaxis, heparins have been recognised as standard therapy for decades. In addition to the therapeutic benefit, therapy with heparins also entails the risk of undesirable side effects, such as bleeding and thrombocytopenia. Heparin-induced thrombocytopenia (HIT II) is deemed a serious side effect.

AIM

In the following work, HIT II is subjected to a medico-economic consideration (treatment, pharmaceuticals, subsequent costs due to possible complications) and, with regard to a possible HIT II prophylaxis, aspects of increasingly respected patient safety are also considered.

METHODS

In the context of a literature search the active ingredients argatroban and danaparoid, which are approved for HIT II treatment, were evaluated.

RESULTS

HIT II - especially in combination with thromboembolic complications - represents a medical-economic burden for the hospital. Although this is only an orientation guide, it shows that HIT II syndrome is not adequately cost-covered by the G‑DRG system. An early thrombosis prophylaxis with argatroban/danaparoid for HIT II risk patients should therefore be taken into account for medical-related as well as patient safety-relevant aspects. According to experience, the pharmaceutical supply for these medically needed products (anticoagulants) should be ensured for reasons of patient safety.

CONCLUSION

The risk of an immunological response to heparin therapy is known. Within the context of increased patient safety, thrombosis prophylaxis should be issued with a risk-adjusted prophylaxis.

Cost-effectiveness of anticoagulants for suspected heparin-induced thrombocytopenia in the United States

Despite the availability of multiple nonheparin anticoagulants for the treatment of heparin-induced thrombocytopenia (HIT), few data are available comparing the cost-effectiveness of these agents. This analysis is particularly important when considering differences in the risk of adverse effects, routes of administration, requirements for phlebotomy and laboratory monitoring, and overall drug costs. We conducted a cost-effectiveness analysis of argatroban, bivalirudin, and fondaparinux for the treatment of suspected HIT from the institutional perspective. A 3-arm decision-tree model was developed that employs standard practices for anticoagulation monitoring. We incorporated published data on drug efficacy and probability of HIT-related thromboembolism and major bleeding. We considered both institutional costs and average wholesale price (AWP) and performed probabilistic sensitivity analyses (PSA) to address any uncertainty in model parameters. Using institutional costs, fondaparinux prevailed over both argatroban and bivalirudin in terms of cost ($151 vs $1250 and $1466, respectively) and adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). Results were consistent when AWP was used, with fondaparinux being less expensive ($555 vs $3081 and $2187, respectively) and more effective in terms of adverse events averted (0.9989 vs 0.9957 and 0.9947, respectively). The PSA confirmed our findings using both institutional costs and AWP. In conclusion, fondaparinux subcutaneous injection afforded significant advantages in terms of cost savings and adverse events averted compared with IV argatroban or bivalirudin infusions. Our data strongly suggest potential cost savings with fondaparinux and underscore the critical need for larger clinical studies of fondaparinux in the treatment of suspected HIT.

How we manage patients with heparin induced thrombocytopenia

Heparin induced thrombocytopenia (HIT) remains a rare, but significant, condition related to mortality and morbidity. The incidence has decreased with reduced use of unfractionated heparin, with the exception of cardiac surgery. Due to the high risk of thrombosis, a switch to a non-heparin anticoagulant is required, until platelet counts normalize. Within the acute setting, argatroban, fondaparinux and direct acting oral anticoagulants (DOACS) are therapeutic options. In patients with HIT-associated thrombosis or who require long-term anticoagulation, warfarin remains the preference, but DOACs are attractive alternatives.

Argatroban in the management of heparin-induced thrombocytopenia: a multicenter clinical trial

Introduction

The aim of this study was to collect data in France in patients with heparin-induced thrombocytopenia who required parenteral anticoagulation and for whom other non-heparin anticoagulant therapies were contraindicated including patients with renal failure, cross-reactivity to danaparoid or at high hemorrhagic risk.

Methods

A total of 20 patients, of mean age 72 ± 10 years, were enrolled in this open-label, multicenter clinical study. Exploratory statistical data analysis was performed with descriptive interpretation of intra-individual comparisons using simple univariate statistics.

Results

The diagnosis of HIT was confirmed in 16 subjects by an independent scientific committee. Fourteen patients (70 %) were in an intensive care unit during the course of the study. Patients were treated with argatroban for a mean duration of 8.5 ± 6.1 days. The mean starting dose of argatroban was 0.77 ± 0.45 μg/kg/min. Platelet recovery was rapid.

aPTT and anti-IIa activity assays were used to monitor the dose of argatroban. The mean baseline aPTT value was 45.0 ± 9.8 sec and increased to 78.2 ± 35.8 sec two hours after initiating argatroban. At this time mean argatroban concentration was 0.34 ± 0.16 and 0.61 ± 0.28 μg/ml using ECT and TT measurements, respectively. New and/or extended thromboses were reported in 25 % of patients and major bleedings were documented in 15 %. Six patients died due to their underlying medical condition.

Conclusion

Considering its hepatic elimination and its short half-life, argatroban can be considered as a safe therapeutic option in HIT patients at high hemorrhagic risk and with renal failure, particularly in an ICU setting.

Safety and economic considerations of argatroban use in critically ill patients: a retrospective analysis

Background

Heparin-induced thrombocytopenia (HIT) causes thromboembolic complications which threaten life and limb. Heparin is administered to virtually every critically ill patient as a protective measure against thromboembolism. Argatroban is a promising alternative anticoagulant agent. However, a safe dose which still provides effective thromboembolic prophylaxis without major bleeding still needs to be identified.

Methods

Critically ill patients (n = 42) diagnosed with HIT at a tertiary medical center intensive care unit from 2005 to 2010 were included in this retrospective analysis. Patient records were perused for preexisting history of HIT, heparin dosage before HIT, argatroban dosage, number of transfusions required, thromboembolic complications and length of ICU stay (ICU LOS). Patients were allocated to Simplified Acute Physiology Scores above and below 30 (SAPS >30, SAPS <30), respectively. For calculations, patients (n = 19) without previous history of HIT were compared to patients (n = 23) with a history of HIT before initiation of argatroban.

Results

The mean initial argatroban dosage was below 0.4 mcg/kg/min regardless of SAPS score. Maintenance dosage had to be increased in patients with SAPS <30 to 0.54 ± 0.248 mcg/kg/min (p >0.05) to achieve effective anticoagulation. No thromboembolic complications were encountered. Argatroban had to be discontinued temporarily in 16 patients for a total of 57 times due to diagnostic or surgical procedures, supratherapeutic aPTT and bleeding without increasing the number of transfusions. A history of HIT was associated with a shorter ICU LOS and significantly reduced transfusion need when compared to patients with no history of HIT. Cost calculation favour argatroban due to increased transfusion needs during heparin administration and increase ICU LOS.

Conclusion

Argatroban can be used at doses < 0.4 mcg/kg/min without an increase in transfusion requirements and at a reduced overall treatment cost compared to heparin.

Argatroban versus Lepirudin in critically ill patients (ALicia): a randomized controlled trial

INTRODUCTION

Critically ill patients often require renal replacement therapy accompanied by thrombocytopenia. Thrombocytopenia during heparin anticoagulation may be due to heparin-induced thrombocytopenia with need for alternative anticoagulation. Therefore, we compared argatroban and lepirudin in critically ill surgical patients.

METHODS

Following institutional review board approval and written informed consent, critically ill surgical patients more than or equal to 18 years with suspected heparin-induced thrombocytopenia, were randomly assigned to receive double-blind argatroban or lepirudin anticoagulation targeting an activated Partial Thromboplastin Time (aPTT) of 1.5 to 2 times baseline. In patients requiring continuous renal replacement therapy we compared the life-time of hemodialysis filters. We evaluated in all patients the incidence of bleeding and thrombembolic events.

RESULTS

We identified 66 patients with suspected heparin-induced thrombocytopenia, including 28 requiring renal replacement therapy. Mean filter lifetimes did not differ between groups (argatroban 32 ± 25 hours (n = 12) versus lepirudin 27 ± 21 hours (n = 16), mean difference 5 hours, 95% CI -13 to 23, P = 0.227). Among all 66 patients, relevant bleeding occurred in four argatroban- versus eleven lepirudin-patients (OR 3.9, 95% CI 1.1 to 14.0, P = 0.040). In the argatroban-group, three thromboembolic events occurred compared to two in the lepirudin group (OR 0.7, 95% CI 0.1 to 4.4, P = 0.639). The incidence of confirmed heparin-induced thrombocytopenia was 23% (n = 15) in our study population.

CONCLUSIONS

This first randomized controlled double-blind trial comparing two direct thrombin inhibitors showed comparable effectiveness for renal replacement therapy, but suggests fewer bleeds in surgical patients with argatroban anticoagulation.

TRIAL REGISTRATION

Clinical Trials.gov NCT00798525. Registered 25 November 2008.

[Argatroban, a new antithrombotic treatment for heparin-induced thrombocytopenia application in cardiac surgery and in intensive care]

OBJECTIVES

Although heparin-induced thrombocytopemia (HIT) is uncommon, its thromboembolic complications are potentially life-threatening. The low-molecular weight heparins are less responsible of HIT than unfractionated heparin (UFH) but this latter is still indicated in some circumstances such as cardiac surgery. Argatroban, a selective thrombin inhibitor, recently available, has been indicated in HIT treatment. This review presents the main pharmacological characteristics, its indications and uses in the context of cardiac surgery and in intensive care medicine.

METHODS

Review of the literature in Medline database over the past 15 years using the following keywords: argatroban, cardiac surgery, circulatory assistance, cardiopulmonary bypass.

RESULTS

Despite its short-acting pharmacokinetic, argatroban cannot be recommended during cardiopulmonary bypass. On the contrary, argatroban is indicated in many circumstances in postoperative period of various cardiac surgeries (on-pump, off-pump, circulatory assistance). Nevertheless, after cardiac surgery, doses have to be adapted according to coagulation laboratory testing (ACT), particularly in patients presenting acute organ failure (kidney injury, heart failure, liver failure). This compound has no antagonist and is excluded during severe hepatic failure. The continuous intravenous administration is a drawback.

CONCLUSION

Argatroban is a new direct competitive thrombin inhibitor well evaluated as treatment of HIT after cardiac surgery. In HIT management, argatroban is an interesting alternative to lepirudin that is not anymore available and danaparoid because of supply disturbances.

Update on argatroban for the prophylaxis and treatment of heparin-induced thrombocytopenia type II

Heparin-induced thrombocytopenia (HIT) is a rare but potentially severe complication of heparin therapy that is strongly associated with venous and arterial thrombosis (HIT and thrombosis syndrome, HITTS), which requires urgent detection and treatment with a nonheparin anticoagulant. Argatroban, a synthetic direct thrombin inhibitor, is indicated for the treatment and prophylaxis of thrombosis in patients with HIT, including those undergoing percutaneous coronary intervention. Argatroban has a relatively short elimination half-life of approximately 45 minutes, which is predominantly performed via hepatic metabolism. It is derived from L-arginine that selectively and reversibly inhibits thrombin, both clot-bound and free, at the catalytic site. Argatroban anticoagulation has been systematically studied in patients with HIT and HITTS and proved to be a safe and effective agent for this indication. The current review presents the pharmacology of argatroban, data regarding monitoring of the agent, and an overview of the results of the major clinical trials assessing argatroban anticoagulation in HIT patients. Additionally, data from recent clinical trials with argatroban use in more special indications such as in percutaneous coronary intervention, liver dysfunction, renal replacement therapy, and intensive care medicine, are reviewed. The approved initial dosage of argatroban for adults with HIT or HITTS is 2 μg/kg/minute for patients with normal hepatic function and 0.5 μg/kg/minute for patients with hepatic dysfunction. There is evidence that a reduced initial dose may also be advisable for patients with heart failure, multiple organ dysfunction, severe anasarca, or after cardiac surgery. Given this information, argatroban can be effectively used in treating HIT with monitoring of activated partial thromboplastin time.

Argatroban therapy in heparin-induced thrombocytopenia

Argatroban is a direct thrombin inhibitor approved for anticoagulation in heparin-induced thrombocytopenia (HIT; in several countries) and in patients with or at risk of HIT undergoing percutaneous coronary intervention (PCI; in the USA). HIT is a relatively common extreme prothrombotic condition. When HIT is reasonably suspected, an alternative anticoagulant should be promptly initiated. In historical controlled studies, argatroban reduced new thrombosis, mortality from thrombosis and the composite of death, amputation or thrombosis, without increasing bleeding. With intravenous infusion, advantages include short half-life, easy monitoring and elimination primarily by hepatobiliary (rather than renal) means. In patients undergoing PCI, argatroban with or without glycoprotein IIb/IIIa inhibition leads to high rates of procedural success with low bleeding risk. Herein we review argatroban therapy for HIT and for PCI.

Use of argatroban: experiences in continuous renal replacement therapy in critically ill patients after cardiac surgery

OBJECTIVES

Acute kidney injury requiring renal replacement therapy (RRT) is a common complication after cardiac surgery, complicated by suspected or proven heparin-induced thrombocytopenia (type II). The present study evaluated the use of argatroban as an anticoagulant during continuous RRT in the early period after cardiac surgery. Argatroban was compared with unfractionated heparin (UH) with respect to bleeding complications and the effectiveness of anticoagulation.

METHODS

Patients requiring RRT after cardiac surgery from March 2007 to June 2009 were identified. The effectiveness of anticoagulation was measured indirectly by the duration of dialysis filter use. Bleeding was defined as clinical signs of blood loss or the need for transfusion.

RESULTS

Of 94 patients, 41 received argatroban, 27 UH, and 26 required conversion from UH to argatroban. In all 3 subgroups, RRT was begun within a median postoperative period of 2.0 days. Similar levels of anticoagulation were achieved with the duration of the circuit and filter changed an average of 1.1 times daily during RRT. Liver function was comparable in all patients. Neither clinically relevant signs of bleeding nor significant differences in the hemoglobin levels or a requirement for transfusion were noted. However, the Simplified Acute Physiology Score II values during dialysis and mortality were significantly greater in the patients initially receiving argatroban compared with those who received UH alone (54 ± 2 vs 43 ± 3, P < .001; 71% vs 44%, P = .04).

CONCLUSIONS

Argatroban can provide effective anticoagulation in postoperative cardiac patients receiving continuous RRT. Close monitoring and dose titration resulted in a comparable risk of bleeding for anticoagulation with both argatroban and heparin, regardless of the disease severity or impaired hepatic function.

Non-recovery of ACT in a patient with heparin-induced thrombocytopenia type II during mitral valve replacement using argatroban anticoagulation

Argatroban was used as the anticoagulant during cardiopulmonary bypass (CPB) in a patient with heparin-induced thrombocytopenia (HIT) type II undergoing mitral valve replacement. Dosage was reduced because of preoperative congestive liver disorder. Perioperative coagulability was poor, and, ultimately, failure of hemostasis led to a fatal outcome. Although argatroban use as an anticoagulant for HIT is reported, the optimal dose has not been established. During long-term CPB, increasing the total dosage may extend anticoagulant ability, leading to dose dependence. Because no antagonist for argatroban exists, failure of hemostasis might occur.

Coagulation management in patients undergoing mechanical circulatory support

The incidence of bleeding and thrombo-embolic complications in patients undergoing mechanical circulatory support therapy remains high and is associated with bad outcomes and increased costs. The need for anticoagulation and anti-platelet therapy varies widely between different pulsatile and non-pulsatile ventricular-assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) systems. Therefore, a unique anticoagulation protocol cannot be recommended. Notably, most thrombo-embolic complications occur despite values of conventional coagulation tests being within the targeted range. This is due to the fact that conventional coagulation tests such as international normalised ratio (INR), activated partial thromboplastin time (aPTT) and platelet count cannot detect hyper- or hypofibrinolysis, hypercoagulability due to tissue factor expression on circulating cells or increased clot firmness, and platelet aggregation as well as response to anti-platelet drugs. By contrast, point-of-care (POC) whole blood viscoelastic tests (thromboelastometry/-graphy) and platelet function tests (impedance or turbidimetric aggregometry) reflect in detail the haemostatic status of patients undergoing mechanical circulatory support therapy and the efficacy of their anticoagulation and antiaggregation therapy. Therefore, monitoring of haemostasis using POC thromboelastometry/-graphy and platelet function analysis is recommended during mechanical circulatory support therapy to reduce the risk of bleeding and thrombo-embolic complications. Notably, these haemostatic tests should be performed repeatedly during mechanical circulatory support therapy since thrombin generation, clot firmness and platelet response may change significantly over time with a high inter- and intra-individual variability. Furthermore, coagulation management can be hampered in non-pulsatile VADs by acquired von Willebrand syndrome, and in general by acquired factor XIII deficiency as well as by heparin-induced thrombocytopenia. In addition, POC testing can be used in bleeding patients to guide calculated goal-directed therapy with allogeneic blood products, haemostatic drugs and coagulation factor concentrates to optimise the haemostasis and to minimise transfusion requirements, transfusion-associated adverse events and to avoid thrombo-embolic complications, as well. However, coagulation management in patients undergoing mechanical circulatory support therapy is somehow like navigating between Scylla and Charybdis, and development of protocols based on POC testing seems to be beneficial.

Argatroban dose reductions for suspected heparin-induced thrombocytopenia complicated by child-pugh class C liver disease

OBJECTIVE

To report our experience of reduced-dose argatroban in a patient with suspected heparin-induced thrombocytopenia (HIT) and Child-Pugh class C liver disease and review the relevant literature to summarize current recommendations on argatroban use in patients with severe liver disease.

CASE SUMMARY

A 58-year-old male with Child-Pugh class C liver disease (Model for End-Stage Liver Disease [MELD] score = 31, total bilirubin 4.5 mg/dL) and hemodialysis-dependent renal failure was hospitalized with acute deep vein thrombosis (DVT). Three days after heparin initiation for DVT, he developed thrombocytopenia. Given his heparin exposure (both for treatment of DVT and ongoing hemodialysis), HIT was suspected and all heparinoids were immediately discontinued. Argatroban was initiated for the treatment of HIT while laboratory testing for HIT antibodies and the serotonin release assay were completed. Because of the patient's advanced liver disease, the starting dose of argatroban was reduced to 0.2 μg/kg/min, with frequent monitoring of the activated partial thromboplastin time (aPTT) (goal 60-85 seconds). Despite this dose reduction, the aPTT was supratherapeutic. Following further dose reductions, a final argatroban maintenance dose of 0.05 μg/kg/min was necessary for the attainment of goal aPTTs.

DISCUSSION

Reducing the starting dose of argatroban to 0.5 μg/kg/min is recommended in patients with liver disease. Nevertheless, this recommended dose is largely based on data from patients with more moderate liver disease (eg, Child-Pugh class A or B), and dosing in more advanced liver disease remains largely unexplored. Patients with more advanced liver disease may require additional dose reductions to avoid supratherapeutic concentrations of anticoagulation agents and to minimize bleeding risk.

CONCLUSIONS

This report illustrates the importance of careful selection of argatroban dosing and appropriate aPTT monitoring in patients with severe liver disease. Excessive anticoagulation may precipitate major bleeding complications, placing patients with this complicated disease at undue risk.

Hats Off to HIT: A Case Report

Thrombocytopenia is a well- recognized complication of heparin therapy. The diagnosis is mostly clinical and the main value of laboratory testing is in excluding the diagnosis. We describe here a patient with stroke who had aspiration pneumonia leading to sepsis. She developed atrial fibrillation and received heparin which had to be stopped prematurely due to melena. Within 5 days of heparin, she had thrombocytopenia which was heparin-induced thrombocytopenia (HIT), but the diagnosis was missed initially as heparin was no longer on the drug chart.

Newer anticoagulants in critically ill patients

Critically ill patients are at increased risk for development of thrombosis. In addition, thrombosis is often unrecognized in this population. Furthermore, these patients are particularly susceptible to bleeding complications from anticoagulants. Herein the authors review the pharmacology, data from clinical trials, management of bleeding complications, and perioperative use of these agents in the intensive care unit population. Well-designed clinical trials are needed to improve our understanding of the safety and efficacy of these newer agents in critically ill patients.

Efficacy of a Nurse-Managed Argatroban Dose-Adjustment Protocol in a University Teaching Hospital

Background

Argatroban is a direct thrombin inhibitor used in the treatment of heparin-induced thrombocytopenia (HIT). No study has evaluated the safety and efficacy of a nurse-managed argatroban dosing protocol.

Methods

We performed a retrospective analysis of 151 total admissions (129 patients) in which argatroban infusions were administered before and after protocol implementation. The preprotocol and postprotocol groups consisted of 69 and 68 admissions, respectively. Patients were eligible for inclusion if they were ≥18 years old and received an argatroban drip for any reason in the 2 years prior to or following protocol implementation.

Results

There were no statistically significant differences in the incidence of clinically overt bleeding (primary study safety endpoint) between groups. There was no difference between groups in the primary efficacy endpoints, the mean number of partial thromboplastin time (aPTT) assessments per day, and dose adjustments. The mean number of sub- and supratherapeutic aPTTs during treatment was higher in the preprotocol group when utilizing the specified range in the preprotocol group and the protocol's aPTT range (45–90 s); the preprotocol and postprotocol groups had an average of 3.4 and 1.04 subtherapeutic aPTTs, respectively ( P = .008). Similarly, the preprotocol group had an average of 4.98 supratherapeutic aPTTs, while the postprotocol group had 1.84 ( P < .001). There was no difference in duration of argatroban infusion in the preprotocol group compared to the postprotocol group with regard to duration of infusion or final infusion rate.

Conclusions

This nurse-managed argatroban adjustment protocol provides similar safety and efficacy outcomes and decreased monitoring when pre and post implementation were compared.

Clinical review: use of renal replacement therapies in special groups of ICU patients

Acute kidney injury (AKI) in ICU patients is typically associated with other severe conditions that require special attention when renal replacement therapy (RRT) is performed. RRT includes a wide range of techniques, each with specific characteristics and implications for use in ICU patients. In the present review we discuss a wide range of conditions that can occur in ICU patients who have AKI, and the implications this has for RRT. Patients at increased risk for bleeding should be treated without anticoagulation or with regional citrate anticoagulation. In patients who are haemodynamically unstable, continuous therapies are most often employed. These therapies allow slow removal of volume and guarantee a stable blood pH. In patients with cerebral oedema, continuous therapy is recommended in order to prevent decreased cerebral blood flow, which will lead to cerebral ischemia. Continuous therapy will also prevent sudden change in serum osmolality with aggravation of cerebral oedema. Patients with hyponatraemia, as in liver failure or decompensated heart failure, require extra attention because a rapid increase of serum sodium concentration can lead to irreversible brain damage through osmotic myelinolysis. Finally, in patients with severe lactic acidosis, RRT can be used as a bridging therapy, awaiting correction of the underlying cause. Especially in ICU patients who have severe AKI, treatment with RRT requires balancing the pros and cons of different options and modalities. Exact and specific guidelines for RRT in these patients are not available for most clinical situations. In the present article we provide an update on the existing evidence.

How I treat heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia is a prothrombotic adverse drug effect induced by platelet-activating antibodies against multimolecular complexes of platelet factor 4 and heparin. Diagnosis rests on a clinical assessment of disease probability and laboratory testing. Management involves immediate discontinuation of heparin and initiation of an alternative anticoagulant. Because of the frequency of thrombocytopenia among heparinized patients, the limited specificity of widely available immunoassays, the limited availability of more specific functional assays, and clinicians' fears of missing a case of true disease, overtesting, overdiagnosis, and overtreatment have become common. As a result, a substantial number of thrombocytopenic patients are unnecessarily exposed to costly alternative anticoagulants and their attendant risk of bleeding. In this review, we describe not only our approach to the evaluation and management of patients with heparin-induced thrombocytopenia, but also the measures we use to minimize misdiagnosis and unnecessary treatment of patients without the disease. In addition, we propose areas of investigation for improvement of the diagnosis and management of this potentially fatal disorder.

Results of a consensus meeting on the use of argatroban in patients with heparin-induced thrombocytopenia requiring antithrombotic therapy - a European Perspective

Argatroban has been introduced as an alternative parenteral anticoagulant for HIT-patients in several European countries in 2005. In 2009 a panel of experts discussed their clinical experience with argatroban balancing risks and benefits of argatroban treatment in managing the highly procoagulant status of HIT-patients. This article summarizes the main conclusions of this round table discussion. An ongoing issue is the appropriate dosing of argatroban in special patient groups. Therefore, dosing recommendations for different HIT-patient groups (ICU patients; non-ICU patients, paediatric patients, and for patients undergoing renal replacement therapies) are summarized in this consensus statement. Because of the strong correlation between argatroban dosing requirements and scores used to characterize the severity of illness (APACHE; SAPS, SOFA) suitable dosing nomograms are given. This consensus statement contributes to clinically relevant information on the appropriate use and monitoring of argatroban based on the current literature, and provides additional information from clinical experience. As the two other approved drugs for HIT, danaparoid and lepirudin are either currently not available due to manufacturing problems (danaparoid) or will be withdrawn from the market in 2012 (lepirudin), this report should guide physicians who have limited experience with argatroban how to use this drug safely in patients with HIT.

Thrombosis prophylaxis in critically ill patients

Incidence of deep vein thrombosis in critically ill patients depends on the underlying disease but may be as high as 60%. The Surviving Sepsis Campaign clearly recommends administering anticoagulation in the absence of specific contraindications in patients with severe sepsis or septic shock. The article discusses risk factor for thromboembolic events in critical illness as well as means of non-pharmacologic and pharmacologic thrombosis prophylaxis. Peripheral vasoconstriction, edema, shock, and administration of catecholamines may reduce the bioavailability and efficacy of subcutaneous administration of low molecular weight heparin. This article further elaborates on the problem and pathophysiology of heparin resistance. Continuous intravenous administration of new anticoagulants may be a promising alternative to indirect anticoagulants. Severity of illness and SAPS II-score determine dosing of the direct thrombin inhibitor argatroban which needs to be about 10-times lower than in patients without critical illness.

Safety and Efficacy of Argatroban in the Management of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life-threatening adverse reaction to heparin therapy that is characterized by thrombocytopenia and an increased risk of venous and arterial thrombosis. According to guidelines, in patients with strongly suspected or confirmed HIT all sources of heparin have to be discontinued and an alternative, nonheparin anticoagulant for HIT treatment must immediately be started. For both the prophylaxis of thrombembolic events in HIT and the treatment of HIT with thrombosis the direct thrombin inhibitor argatroban is approved in the United States. The objective of this review is to describe the mechanism of action and the pharmacokinetic profile of argatroban, to characterize argatroban regarding its safety and therapeutic efficacy and to discuss its place in therapy in HIT.

[Heparin-induced thrombocytopenia]

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction that carries an increased risk of thromboembolic complications. HIT is caused by platelet-activating antibodies directed against a complex of platelet factor 4 (PF4) and heparin. HIT typically manifests in the second week after initiation of heparin therapy with a platelet count reduction of more than 50% of the highest level after the start of heparin administration as well as thromboembolic events. The clinical probability can be calculated by the 4 T's score. The laboratory diagnosis of HIT is based on confirmation of PF4/heparin antibodies or on functional tests that provide evidence of heparin-dependent platelet-activating antibodies. A low 4 T's score and negative HIT test virtually rule out the presence of HIT. Patients with acute HIT require anticoagulation with a compatible anticoagulant in a therapeutic dose. The drugs currently available for this include the direct thrombin inhibitors argatroban, lepirudin, bivalirudin, and desirudin and the indirect factor Xa inhibitors danaparoid and fondaparinux.

[Management of complex thrombocytopenia with thrombelastometry : a case of simultaneous posttransfusion purpura and heparin-induced thrombocytopenia]

The case presented describes the combined onset of heparin-induced thrombocytopenia II (HIT) and post-transfusion purpura (PTP) 5-10 days following exposure to heparin and blood transfusion during aortic dissection repair. On day 4 the platelet count decreased by 40% and D-dimers started to increase again. Despite a low clinical probability for HIT-II at this time (4T score of 3) serological testing was done the next day and yielded a negative test result. Following a transient rise after platelet transfusion another 40% decrease in platelet count occurred on day 8. To increase precision of the 4T score, screening ultrasonography was performed and identified a clinically unapparent jugular vein thrombosis. As this increased the 4T score to 6 points, serological testing was repeated and now showed the presence of HIT-II antibodies. Despite switching from heparin to argatroban the platelet count continued to decrease to <5×10(3)/µl. Conventional clotting tests showed a prolonged prothrombin time and severe hypofibrinogenemia. Because of the female sex, age >50 years, history of pregnancy and transfusion 8 days before, PTP was suspected. The alteration of the plasmatic coagulation, however, could not be explained by PTP. Therefore, disseminated intravascular coagulation (DIC) and interference of argatroban with conventional clotting tests were considered as alternative diagnoses. In order to differentiate between the two alternatives rotational thrombelastometry (ROTEM®) was performed and revealed an increased functional fibrinogen level without signs of hyperfibrinolysis. This argued for an interference of argatroban with the Clauss method of fibrinogen measurement and rendered DIC unlikely. Under suspicion of PTP, treatment with immunoglobulin was initiated and blood transfusions were avoided. Detection of PTP antibodies 1 day later confirmed the combined presence of PTP and HIT-II. As hyperfibrinogenemia compensated for the effects of thrombocytopenia on clot firmness in ROTEM®, anticoagulation with lepirudin was started at 9×10(3) platelets/µl only. The next day the platelet count increased to 32×10(3)/µl and clot firmness returned to normal. No thromboembolic complications and no relevant bleeding were observed. In summary, this case shows for the first time that HIT-II and PTP can occur in parallel in patients with simultaneous exposure to heparin and blood transfusions. Confounding effects of argatroban on conventional clotting tests may mimic DIC under these circumstances and make diagnosis difficult. Careful evaluation of the time-related magnitude in platelet decrease, patient history, course of D-dimers, screening ultrasonography and ROTEM® seem to be helpful to initiate early appropriate therapy before serological test results become available. In contrast to the Clauss method of fibrinogen measurement, assessment of clot firmness in ROTEM® is not influenced by argatroban. Moreover, ROTEM® reveals the compensatory effects of increased functional fibrinogen on clot firmness during severe thrombocytopenia as an important variable for anticoagulation therapy during thrombocytopenia with increased thromboembolic risk.

Monitoring of the anticoagulants argatroban and lepirudin: a comparison of laboratory methods

Monitoring of direct inhibitors of thrombin (DTI) is critical for their safe and effective use as anticoagulants. We examined samples containing several concentrations of argatroban or lepirudin in reconstituted standard human plasma and plasma from medical outpatients and intensive care patients. Prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT) were determined using automated analyzers. Ecarin clotting time (ECT) was measured using a 10 IU/mL dilution of ecarin in 0.05 mol/L CaCl(2). Calibration curves were approximately linear for TT and ECT in samples containing argatroban and lepirudin, respectively. Activated partial thromboplastin curves reached a plateau at DTI concentrations ≥2 µg/mL, suggesting that the aPTT may not reliably detect overdosing. Prothrombin time increased exponentially. A broad range of clotting times was seen in patient samples with all tests suggesting that individual morbidity and therapies may strongly influence test results and may lead to underestimation of DTI doses.

Argatroban in the management of heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an immunoglobulin-mediated serious complication of heparin therapy characterized by thrombocytopenia and high risk for venous and arterial thrombosis: HIT and thrombosis syndrome (HITTS). Argatroban, a direct thrombin inhibitor, is indicated as the anticoagulant for the treatment and prophylaxis of thrombosis in patients with HIT and in patients undergoing percutaneous coronary intervention (PCI) who have HIT. The aim of this review is to examine the pharmacological characteristics and the clinical efficacy and safety of this drug in adults with HIT, including those undergoing PCI. Briefly, 2 prospective multicenter, nonrandomized, open-label studies evaluated the efficacy and safety of argatroban as an anticoagulant in patients with HIT or HITTS. Both studies showed that the incidence of the primary efficacy end point, a composite of all-cause death, all-cause amputation, or new thrombosis, was reduced in argatroban-treated patients vs control subjects with HIT or HITTS. In both studies, bleeding rates were similar between the groups. Argatroban was evaluated as the anticoagulant therapy in 3 prospective, multicenter, open-label studies in HIT patients who underwent PCI. The studies were similar in design with respect to patient inclusion and exclusion criteria, the argatroban dosing regimen, and primary efficacy outcomes. The investigators performed a pooled analysis of these studies, which showed that most (≥95%) patients achieved a satisfactory outcome from the procedure and adequate anticoagulation (coprimary end points).