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

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.

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.

Pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is a major comorbidity in hospitalised patients. Patients with severe AKI require continuous renal replacement therapy (CRRT) when they are haemodynamically unstable. CRRT is prescribed assuming it is delivered over 24 hours. However, it is interrupted when the extracorporeal circuits clot and the replacement is required. The interruption may impair the solute clearance as it causes under dosing of CRRT. To prevent the circuit clotting, anticoagulation drugs are frequently used.

OBJECTIVES

To assess the benefits and harms of pharmacological interventions for preventing clotting in the extracorporeal circuits during CRRT.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 September 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs or cluster RCTs) and quasi-RCTs of pharmacological interventions to prevent clotting of extracorporeal circuits during CRRT.

DATA COLLECTION AND ANALYSIS

Data were abstracted and assessed independently by two authors. Dichotomous outcomes were calculated as risk ratio (RR) with 95% confidence intervals (CI). The primary review outcomes were major bleeding, successful prevention of clotting (no need of circuit change in the first 24 hours for any reason), and death. Evidence certainty was determined using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach.

MAIN RESULTS

A total of 34 completed studies (1960 participants) were included in this review. We identified seven ongoing studies which we plan to assess in a future update of this review. No included studies were free from risk of bias. We rated 30 studies for performance bias and detection bias as high risk of bias. We rated 18 studies for random sequence generation,ààsix studies for the allocation concealment, three studies for performance bias, three studies for detection bias,à nine studies for attrition bias,à14 studies for selective reporting and nine studies for the other potential source of bias, as having low risk of bias. We identified eight studies (581 participants) that compared citrate with unfractionated heparin (UFH). Compared to UFH, citrate probably reduces major bleeding (RR 0.22, 95% CI 0.08 to 0.62; moderate certainty evidence) and probably increases successful prevention of clotting (RR 1.44, 95% CI 1.10 to 1.87; moderate certainty evidence). Citrate may have little or no effect on death at 28 days (RR 1.06, 95% CI 0.86 to 1.30, moderate certainty evidence). Citrate versus UFH may reduce the number of participants who drop out of treatment due to adverse events (RR 0.47, 95% CI 0.15 to 1.49; low certainty evidence). Compared to UFH, citrate may make little or no difference to the recovery of kidney function (RR 1.04, 95% CI 0.89 to 1.21; low certainty evidence). Compared to UFH, citrate may reduceàthrombocytopenia (RR 0.39, 95% CI 0.14 to 1.03; low certainty evidence). It was uncertain whether citrate reduces a cost to health care services because of inadequate data. For low molecular weight heparin (LMWH) versus UFH, six studies (250 participants) were identified. Compared to LMWH, UFH may reduce major bleeding (0.58, 95% CI 0.13 to 2.58; low certainty evidence). It is uncertain whether UFH versus LMWH reduces death at 28 days or leads to successful prevention of clotting. Compared to LMWH, UFH may reduce the number of patient dropouts from adverse events (RR 0.29, 95% CI 0.02 to 3.53; low certainty evidence). It was uncertain whether UFH versus LMWH leads to the recovery of kidney function because no included studies reported this outcome. It was uncertain whether UFH versus LMWH leads to thrombocytopenia. It was uncertain whether UFH reduces a cost to health care services because of inadequate data. For the comparison of UFH to no anticoagulation, one study (10 participants) was identified. It is uncertain whether UFH compare to no anticoagulation leads to more major bleeding. It is uncertain whether UFH improves successful prevention of clotting in the first 24 hours, death at 28 days, the number of patient dropouts due to adverse events, recovery of kidney function, thrombocytopenia, or cost to health care services because no study reported these outcomes. For the comparison ofàcitrate to no anticoagulation,àno completed study was identified.

AUTHORS' CONCLUSIONS

Currently,àavailable evidence does not support the overall superiority of any anticoagulant to another. Compared to UFH, citrate probably reduces major bleeding and prevents clotting and probably has little or no effect on death at 28 days. For other pharmacological anticoagulation methods, there is no available data showing overall superiority to citrate or no pharmacological anticoagulation. Further studies are needed to identify patient populations in which CRRT should commence with no pharmacological anticoagulation or with citrate.

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.

Pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is a major comorbidity in hospitalised patients. Patients with severe AKI require continuous renal replacement therapy (CRRT) when they are haemodynamically unstable. CRRT is prescribed assuming it is delivered over 24 hours. However, it is interrupted when the extracorporeal circuits clot and the replacement is required. The interruption may impair the solute clearance as it causes under dosing of CRRT. To prevent the circuit clotting, anticoagulation drugs are frequently used.

OBJECTIVES

To assess the benefits and harms of pharmacological interventions for preventing clotting in the extracorporeal circuits during CRRT.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 12 September 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs or cluster RCTs) and quasi-RCTs of pharmacological interventions to prevent clotting of extracorporeal circuits during CRRT.

DATA COLLECTION AND ANALYSIS

Data were abstracted and assessed independently by two authors. Dichotomous outcomes were calculated as risk ratio (RR) with 95% confidence intervals (CI). The primary review outcomes were major bleeding, successful prevention of clotting (no need of circuit change in the first 24 hours for any reason), and death. Evidence certainty was determined using the Grading of Recommendation Assessment, Development, and Evaluation (GRADE) approach.

MAIN RESULTS

A total of 34 completed studies (1960 participants) were included in this review. We identified seven ongoing studies which we plan to assess in a future update of this review. No included studies were free from risk of bias. We rated 30 studies for performance bias and detection bias as high risk of bias. We rated 18 studies for random sequence generation,  six studies for the allocation concealment, three studies for performance bias, three studies for detection bias,  nine studies for attrition bias, 14 studies for selective reporting and nine studies for the other potential source of bias, as having low risk of bias. We identified eight studies (581 participants) that compared citrate with unfractionated heparin (UFH). Compared to UFH, citrate probably reduces major bleeding (RR 0.22, 95% CI 0.08 to 0.62; moderate certainty evidence). Citrate may have little or no effect on death at 28 days (RR 1.06, 95% CI 0.86 to 1.30, moderate certainty evidence), while citrate versus UFH may have little or no effect on successful prevention of clotting (RR 1.01, 95% CI 0.77 to 1.32; moderate certainty evidence). Citrate versus UFH may reduce the number of participants who drop out of treatment due to adverse events (RR 0.47, 95% CI 0.15 to 1.49; low certainty evidence). Compared to UFH, citrate may make little or no difference to the recovery of kidney function (RR 0.95, 95% CI 0.66 to 1.36; low certainty evidence). Compared to UFH, citrate may reduce thrombocytopenia (RR 0.39, 95% CI 0.14 to 1.03; low certainty evidence). It was uncertain whether citrate reduces a cost to health care services because of inadequate data. For low molecular weight heparin (LMWH) versus UFH, six studies (250 participants) were identified. Compared to LMWH, UFH may reduce major bleeding (0.58, 95% CI 0.13 to 2.58; low certainty evidence). It is uncertain whether UFH versus LMWH reduces death at 28 days or leads to successful prevention of clotting. Compared to LMWH, UFH may reduce the number of patient dropouts from adverse events (RR 0.29, 95% CI 0.02 to 3.53; low certainty evidence). It was uncertain whether UFH versus LMWH leads to the recovery of kidney function because no included studies reported this outcome. It was uncertain whether UFH versus LMWH leads to thrombocytopenia. It was uncertain whether UFH reduces a cost to health care services because of inadequate data. For the comparison of UFH to no anticoagulation, one study (10 participants) was identified. It is uncertain whether UFH compare to no anticoagulation leads to more major bleeding. It is uncertain whether UFH improves successful prevention of clotting in the first 24 hours, death at 28 days, the number of patient dropouts due to adverse events, recovery of kidney function, thrombocytopenia, or cost to health care services because no study reported these outcomes. For the comparison of citrate to no anticoagulation, no completed study was identified.

AUTHORS' CONCLUSIONS

Currently, available evidence does not support the overall superiority of any anticoagulant to another. Compared to UFH, citrate probably reduces major bleeding and probably has little or no effect on preventing clotting or death at 28 days. For other pharmacological anticoagulation methods, there is no available data showing overall superiority to citrate or no pharmacological anticoagulation. Further studies are needed to identify patient populations in which CRRT should commence with no pharmacological anticoagulation or with citrate.

Recommendations for Therapeutic Apheresis by the Section "Preparative and Therapeutic Hemapheresis" of the German Society for Transfusion Medicine and Immunohematology

The section "Preparative and Therapeutic Hemapheresis" of the German Society for Transfusion Medicine and Immunohematology (DGTI) has reviewed the actual literature and updated techniques and indications for evidence-based use of therapeutic apheresis in human disease. The recommendations are mostly in line with the "Guidelines on the Use of Therapeutic Apheresis in Clinical Practice" published by the Writing Committee of the American Society for Apheresis (ASFA) and have been conducted by experts from the DACH (Germany, Austria, Switzerland) region.

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.

The Evaluation of Pharmacodynamics and Pharmacokinetics of Anti-thrombin DNA Aptamer RA-36

Anticoagulants are a vital class of drugs, which are applied for short-term surgical procedures, and for long-term treatments for thrombosis prevention in high risk groups. Several anticoagulant drugs are commercially available, but all have intrinsic disadvantages, e.g., bleeding risks, as well as specific ones, e.g., immune response to peptide/protein drugs. Therefore, the search for novel, efficient and safe anticoagulants is essential. Nucleic acid aptamers are an emerging class of contemporary pharmaceuticals which are fully biocompatible and biodegradable; they have low toxicity, and are as efficient as many protein-based drugs. The anti-thrombin DNA aptamer RA-36 has been created using a combination of rational design and molecular dynamics, showing several extra-features over existing aptamers. Aptamer RA-36 has a bimodular structure; the first G-quadruplex binds and inhibits thrombin, whereas the second G-quadruplex varies the properties of the first. This bimodular structure provides a favorable dose-effect dependence allowing the risk of bleeding to be potentially decreased. Here, the results of efficiency trials of the aptamer are presented. The aptamer RA-36 has a distinctive species specificity; therefore, the careful selection of experimental animals was required. The anticoagulant activity was characterized in rats and monkeys in vivo. Antithrombotic activity was evaluated in the live murine model of the induced thrombosis. Pharmacokinetics was estimated by tracking radionuclide labeled aptamer in rats. The aptamer was thoroughly characterized using bivalirudin as a reference drug. Despite the different profiles of anticoagulant activity, these two compounds could refer to each other, and the corresponding doses could be estimated. Bivalirudin turned out to have 10-fold higher anticoagulant and antithrombotic activity. The difference in activity is easy to explain due to the pharmacokinetic profiles of the substances: the aptamer RA-36 has 20-fold faster elimination from blood with a half-life of 1 min. The entire dataset revealed that the non-modified DNA aptamer could be an alternative to the currently used bivalent peptide inhibitor; the dosage profile could be improved by manipulating aptamer pharmacokinetics. The study has revealed aptamer RA-36 to be one of the most promising candidates for further development as a new generation of anticoagulants.

Management of heparin-induced thrombocytopenia

PURPOSE OF REVIEW

The purpose of this review is to summarize recent findings on heparin-induced thrombocytopenia (HIT), a prothrombotic disorder caused by platelet-activating IgG targeting platelet factor 4 (PF4)/polyanion complexes.

RECENT FINDINGS

HIT can explain unusual clinical events, including adrenal hemorrhages, arterial/intracardiac thrombosis, skin necrosis, anaphylactoid reactions, and disseminated intravascular coagulation. Sometimes, HIT begins/worsens after stopping heparin ('delayed-onset' HIT). Various HIT-mimicking disorders are recognized (e.g., acute disseminated intravascular coagulation/'shock liver' with limb ischemia). HIT has features of both B-cell and T-cell immune responses; uptake of PF4/heparin complexes into macrophages ('macropinocytosis') facilitates the anti-PF4/heparin immune response. Antibody-induced activation of monocytes and platelets via their FcγIIA receptors triggers an intense procoagulant response. Sometimes, HIT antibodies recognize PF4 bound to (platelet-associated) chondroitin sulfate, explaining how HIT might occur without concurrent or recent heparin (delayed-onset HIT, 'spontaneous HIT syndrome'). The molecular structure of HIT antigen(s) has been characterized, providing a rationale for future drug design to avoid HIT and improve its treatment. The poor correlation between partial thromboplastin time and plasma argatroban levels (risking subtherapeutic anticoagulation) and need for intravenous administration of argatroban have led to increasing 'off-label' treatment with fondaparinux or one of the direct oral anticoagulants.

SUMMARY

Understanding the molecular mechanisms and unusual clinical features of HIT will improve its management.

Renal replacement therapy and anticoagulation

Today, up to 20% of all intensive care unit patients require renal replacement therapy (RRT), and continuous renal replacement therapies (CRRT) are the preferred technique. In CRRT, effective anticoagulation of the extracorporeal circuit is mandatory to prevent clotting of the circuit or filter and to maintain filter performance. At present, a variety of systemic and regional anticoagulation modes for CRRT are available. Worldwide, unfractionated heparin is the most widely used anticoagulant. All systemic techniques are associated with significant adverse effects. Most important are bleeding complications and heparin-induced thrombocytopenia (HIT-II). Regional citrate anticoagulation (RCA) is a safe and effective technique. Compared to systemic anticoagulation, RCA prolongs filter running times, reduces bleeding complications, allows effective control of acid-base status, and reduces adverse events like HIT-II. In this review, we will discuss systemic and regional anticoagulation techniques for CRRT including anticoagulation for patients with HIT-II. Today, RCA can be recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.

Effectiveness and Safety Assessment of Citrate Anticoagulation During Albumin Dialysis in Comparison to Other Methods of Anticoagulation

Liver failure is a serious and often deadly disease often requiring MARS (Molecular Adsorbent Recirculating System) therapy. Choosing the safe and effective method of anticoagulation during artificial liver support systems seems to be very difficult and extremely important. The aim of this study was to assess effectiveness and safety of regional anticoagulation with citrate in liver failure patients during MARS. We used a single center observational study. We analyzed 158 MARS sessions performed in 65 patients: 105 (66.5%) sessions in 41 patients with heparin anticoagulation, 40 (25.3%) sessions in 19 patients with citrate, and 13 (8%) sessions in only five patients without anticoagulation, that were excluded from part of the analysis. To determine the effectiveness of regional anticoagulation with citrate, probability of filter survival and changes in laboratory parameters were analyzed according to the applied method of anticoagulation. The safety of citrate was determined by Ca/Ca²⁺ ratio, acid-base balance, bleeding complications, and the need for blood product transfusions. The probability of filter survival in the citrate group was 94% and in the heparin group 82% (P = 0.204). There was no relationship between the method of anticoagulation and effectiveness of MARS therapy in lowering the levels of the analyzed parameters. Only one patient had a Ca/Ca²⁺ ratio higher than he safety margin. There were no statistically significant changes in pH and lactate level irrespective of anticoagulation; bicarbonate dropped significantly only in the heparin group (P = 0.03). The frequency of bleeding complications and the need for transfusions did not differ significantly between groups. Regional anticoagulation with citrate can be an effective and safe method of anticoagulation during MARS therapy, but requires attentive monitoring and further studies in liver failure patients.

Monitoring of Argatroban and Lepirudin: What is the Input of Laboratory Values in "Real Life"?

Monitoring of direct thrombin inhibitors (DTIs) in patients with heparin-induced thrombocytopenia (HIT) is primarily performed using the activated partial thromboplastin time (aPTT). This assay is poorly standardized, reagent dependent, and not DTI specific. We compared aPTT, thrombin time (TT), and prothrombin time (PT) to drug levels obtained by the ecarin chromogenic assay (ECA). We analyzed 495 samples of patients with confirmed or suspected HIT on treatment with either argatroban (n = 37) or lepirudin (n = 80). Mean DTI levels ± standard deviation (SD) were 0.41 ± 0.36 µg/mL for argatroban and 0.20 ± 0.21 µg/mL for lepirudin. Results of aPTT were highly variable: 67 ± 22 seconds for argatroban and 55 ± 20 seconds for lepirudin. Significant correlations ( P < .01) were found between ECA-based DTI level and TT (argatroban, r = .820 and lepirudin, r = .830), PT (argatroban, r = -.544), and aPTT (lepirudin, r = .572). However, there was no correlation of aPTT with argatroban or PT with lepirudin concentration. Multiple regression analyses revealed that the TT predicted 54% of argatroban and 42% of lepirudin levels, but no significant impact was seen for PT or aPTT. The aPTT-guided monitoring of DTI therapy leads to a high percentage of patients with inaccurate plasma levels, hence resulting to either undertreatment or overtreatment. Knowledge of baseline values prior to DTI therapy and inclusion of clinical settings are essential for dosing DTIs when using aPTT. However, due to several limitations of aPTT, monitoring according to exact plasma concentrations as obtained by specific tests such as ECA may be more appropriate.

Argatroban for anticoagulation of a blood salvage system - an ex-vivo study

BACKGROUND

Blood salvage systems help to minimize intraoperative transfusion of allogenic blood. So far no data is available on the use of argatroban for anticoagulation of such systems. We conducted an ex-vivo trial to evaluate the effectiveness of three different argatroban doses as compared to heparin and to assess potential residual anticoagulant in the red cell concentrates.

METHODS

With ethical approval and individual informed consent, blood of 23 patients with contraindications for use of blood salvage systems during surgery was processed by the Continuous-Auto-Transfusion-System (C.A.T.S. ® Cell Saver System, Fresenius Kabi, Bad Homburg, Germany) using 5,50 or 250 mg of argatroban or 25.000 U of heparin in 1000 ml saline for anticoagulation of the system. Emergency and high-quality washing modes were applied in random order. Patency of the system and residual amount of anticoagulants in the re-transfusion bag were measured. The collected blood was not re-infused, but only used for analysis of hematocrit, heparin and argatroban concentrations.

RESULTS

Patency of the system was provided by all anticoagulants except for 3/8 cases with 5 mg of argatroban. Residual anticoagulant was found in 2/10 (20 %) heparin samples in two different patients (1 emergency and 1 high-quality washing) and in all argatroban samples. High quality washing eliminated 89-95 % and emergency washing 60-90 % of the initial argatroban concentration. Residual argatroban concentrations ranged from 55 ng ml(-1) to 6810 ng ml(-1), with initial argatroban concentrations of 5 and 250 mg, respectively.

CONCLUSION

The C.A.T.S. does not reliably remove heparin and should therefore not be used in HIT patients. Anticoagulation with 50 and 250 mg argatroban, maintains the systems patency and is significantly removed during washing. In this ex-vivo study a concentration of 50 μg ml(-1) argatroban provided the best ratio of system patency and residual argatroban concentration. Additional dose-finding studies with different blood salvage systems are needed to evaluate the optimal argatroban concentration.

Anticoagulants in children and adolescents

Thrombotic complications are increasing at a steady and significant rate in children, resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the older multitargeted agents (heparin, low-molecular-weight heparin, and warfarin) and the newer targeted agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the multitargeted and targeted anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. The various agents differ in their pharmacokinetics, requirements for therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The targeted anticoagulants have properties that may make them more attractive for use in specific clinical situations. Prospective clinical trial data are presented supporting the current and future use of these agents in children.

Anticoagulants in children and adolescents

Thrombotic complications are increasing at a steady and significant rate in children, resulting in the more widespread use of anticoagulation in this population. Anticoagulant drugs in children can be divided into the older multitargeted agents (heparin, low-molecular-weight heparin, and warfarin) and the newer targeted agents (argatroban, bivalirudin, and fondaparinux). This review will compare and contrast the multitargeted and targeted anticoagulants and suggest situations in which it may be appropriate to use argatroban, bivalirudin, and fondaparinux. The various agents differ in their pharmacokinetics, requirements for therapeutic drug monitoring, frequency of administration, efficacy, and adverse effects. The targeted anticoagulants have properties that may make them more attractive for use in specific clinical situations. Prospective clinical trial data are presented supporting the current and future use of these agents in children.