Removal of lepirudin, a recombinant hirudin, by hemodialysis, hemofiltration, or plasmapheresis

The efficacy and safety of Hirudin plus Aspirin versus Warfarin in the secondary prevention of Cardioembolic Stroke due to Nonvalvular Atrial Fibrillation: A multicenter prospective cohort study

Background: To investigate the efficacy and safety of hirudin plus aspirin therapy compared with warfarin in the secondary prevention of cardioembolic stroke due to nonvalvular atrial fibrillation (NVAF). Methods: Patients with cardioembolic stroke due to NVAF were prospectively enrolled from 18 collaborating hospitals from Dec 2011 to June 2015. Fourteen days after stroke onset, eligible patients were assigned to the hirudin plus aspirin group (natural hirudin prescribed as the traditional Chinese medicine Maixuekang capsule, 0.75 g, three times daily, combined with aspirin 100 mg, once daily) or the warfarin group (dose-adjusted warfarin targeting international normalized ratio (INR) 2-3, with an initial daily dose of 1.25 mg). Patients were followed up at 1, 2, 3, 6, 9, and 12 months after stroke onset. Time in therapeutic range (TTR) was calculated according to Rosendaal methodology to evaluate the quality of INR management in the warfarin group. The primary efficacy endpoint was the recurrence of stroke within 12 months after stroke onset. Safety was assessed as the occurrence of the composite event "intracranial hemorrhage and other bleeding events, death, and other serious adverse events". The Cox proportional hazard model and Kaplan-Meier curve were used to analyze the efficacy and safety events. Results: A total of 221 patients entered final analysis with 112 patients in the hirudin plus aspirin group and 109 in the warfarin group. Over the whole duration of our study, TTR for patients taking warfarin was 66.5 % ± 21.5%. A significant difference was not observed in the recurrence of stroke between the two groups (3.57% vs. 2.75%; P = 0.728). The occurrence of safety events was significantly lower in the hirudin plus aspirin group (2.68% vs.10.09%; P = 0.024). The risk for efficacy event was similar between the two groups (hazard ratio (HR), 1.30; 95% confidence interval (CI), 0.29-5.80). The safety risk was significantly lower in the hirudin plus aspirin group (HR, 0.27; 95% CI, 0.07-0.95). Kaplan-Meier analysis revealed significant difference in the temporal distribution in safety events (P = 0.023) but not in stroke recurrence (P = 0.726). Conclusion: Significant difference in efficacy was not detected between warfarin group and hirudin plus aspirin group. Compared with warfarin, hirudin plus aspirin therapy had lower safety risk in the secondary prevention of cardioembolic stroke due to NVAF.

Perioperative care in an adolescent patient with heparin-induced thrombocytopenia for placement of a cardiac assist device and heart transplantation: case report and literature review

Heparin-induced thrombocytopenia (HIT) can cause life-threatening complications following the administration of heparin. Discontinuation of all sources of heparin exposure and the use of alternative agents for anticoagulation are necessary when HIT is suspected or diagnosed. We present the successful use of bivalirudin anticoagulation in an adolescent patient during cardiopulmonary bypass who underwent both placement of a left ventricular assist device and subsequent heart transplantation within a 36-hour period. The pathophysiology and diagnosis of HIT are reviewed, previous reports of the use of direct thrombin inhibitors for cardiac surgery are presented, and potential dosing regimens for bivalirudin are discussed.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care Anticoagulation and Thrombolysis

OBJECTIVE

Thrombotic complications are increasingly being recognized as a significant cause of morbidity and mortality in pediatric and congenital heart disease. The objective of this article is to review the medications currently available to prevent and treat such complications.

DATA SOURCES

Online searches were conducted using PubMed.

STUDY SELECTION

Studies were selected for inclusion based on their scientific merit and applicability to the pediatric cardiac population.

DATA EXTRACTION

Pertinent information from each selected study or scientific review was extracted for inclusion.

DATA SYNTHESIS

Four classes of medications were identified as potentially beneficial in this patient group: anticoagulants, antiplatelet agents, thrombolytic agents, and novel oral anticoagulants. Data on each class of medication were synthesized into the follow sections: mechanism of action, pharmacokinetics, dosing, monitoring, reversal, considerations for use, and evidence to support.

CONCLUSIONS

Anticoagulants, antiplatelet agents, and thrombolytic agents are routinely used successfully in the pediatric patient with heart disease for the prevention and treatment of a wide range of thrombotic complications. Although the novel oral anticoagulants have been approved for a limited number of indications in adults, studies on the safety and efficacy of these agents in children are pending.

Anticoagulation management associated with extracorporeal circulation

The use of extracorporeal circulation requires anticoagulation to maintain blood fluidity throughout the circuit, and to prevent thrombotic complications. Additionally, adequate suppression of hemostatic activation avoids the unnecessary consumption of coagulation factors caused by the contact of blood with foreign surfaces. Cardiopulmonary bypass represents the greatest challenge in this regard, necessitating profound levels of anticoagulation during its conduct, but also quick, efficient reversal of this state once the surgical procedure is completed. Although extracorporeal circulation has been around for more than half a century, many questions remain regarding how to best achieve anticoagulation for it. Although unfractionated heparin is the predominant agent used for cardiopulmonary bypass, the amount required and how best to monitor its effects are still unresolved. This review discusses the use of heparin, novel anticoagulants, and the monitoring of anticoagulation during the conduct of cardiopulmonary bypass.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Medications in patients treated with therapeutic plasma exchange: prescription dosage, timing, and drug overdose

Therapeutic plasma exchange (TPE) is an extracorporeal process commonly used in clinical medicine for the treatment of a variety of neurological, renal, hematological, dermatological, and other diseases. Inherent to the procedure, patients' plasma removal may lead to the extraction of drugs they are concurrently receiving. This review discusses the published literature assessing TPE's influence on different drug classes' disposition and, when applicable, sets forth management recommendations in cases where the drugs are used at the usual doses and in cases of drug overdose.

Drug removal by plasmapheresis: an evidence-based review

Contrary to the literature about drug removal during hemodialysis, data regarding drug removal during plasmapheresis are sparse. Over the last 40 years, approximately 70 publications-mostly case reports of overdoses-have described the effects of plasmapheresis on pharmaceutical agents. Important issues are drug extraction during plasma exchange with chemotherapy, as well as drug classes such as antiinfectives, anticoagulants, antiepileptics, cardiovascular agents, and immunosuppressants. Other considerations are the merits and pitfalls of the different methods used in published reports and recommendations for future pharmacokinetic studies in this field.

Heparin-Induced Thrombocytopenia: Treatment Options and Special Considerations

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse effect that typically manifests several days after the start of heparin therapy, although both rapid- and delayed-onset HIT have been described. Its most serious complication is thrombosis. Although not all patients develop thrombosis, it can be life threatening. The risk of developing HIT is related to many factors, including the type of heparin product administered, route of administration, duration of therapy, patient population, and previous exposure to heparin. The diagnosis of HIT is typically based on clinical presentation, exposure to heparin, and presence of thrombocytopenia with or without thrombosis. Antigen and activation laboratory assays are available to support the diagnosis of HIT. However, because of the limited sensitivity and specificity of these assays, bedside probability scales for HIT were developed. When HIT is suspected, prompt cessation of all heparin therapy is necessary, along with initiation of alternative anticoagulant therapy. Two direct thrombin inhibitors--argatroban and lepirudin--are approved for the management of HIT in the United States, and bivalirudin is approved for use in patients with HIT who are undergoing percutaneous coronary intervention. Other agents, although not approved to manage HIT, have also been used; however, their role in therapy requires further evaluation. A comprehensive HIT management strategy involves the evaluation of numerous factors. Many patients, including those undergoing coronary artery bypass surgery, those with acute coronary syndromes, those with hepatic or renal insufficiency, and children, require special attention. Clinicians must become familiar with the available information on this serious adverse effect and its treatment so that optimum patient management strategies may be formulated.

Hemofiltration of recombinant hirudin by different hemodialyzer membranes: implications for clinical use

Recombinant hirudin (lepirudin) is a potent direct thrombin inhibitor that is used particularly for treatment of immune-mediated heparin-induced thrombocytopenia. Because hirudin is almost exclusively eliminated by the kidneys, its half-life is markedly prolonged in patients with severe renal insufficiency. Therefore, these patients are at risk for bleeding, particularly because no antidote is available. To use hirudin safely in patients who are on renal replacement therapy, knowledge of hirudin-sieving characteristics of different hemodialyzers is required. Data on this issue are sparse and in part contradictory. Eight different conventional low-flux and high-flux hemodialyzers were tested in an in vitro circuit with ultrafiltrate reinfusion. In each experiment, lepirudin concentration was repetitively measured during 3 h in the prefilter, the postfilter, and the filtration line using a chromogenic assay. On the basis of these data, sieving coefficients were calculated. All high-flux hemodialyzers tested allowed filtration of hirudin yet with marked differences in steady-state sieving (sieving coefficients in whole blood: polysulfone [PS] 0.97 +/- 0.03; polymethylmethacrylate [PMMA] 0.75 +/- 0.02; polyarylethersulfone 0.73 +/- 0.02; polyamide 0.49 +/- 0.02). None of the low-flux hemodialyzer membranes tested (cuprophane, hemophane, PS, and PMMA) showed significant hirudin filtration. Owing to marked differences in hirudin-sieving characteristics, choice of the appropriate hemodialyzer membrane is an important determinant of bleeding risk in dialysis-dependent patients who are treated with hirudin. In case of overdosage or bleeding complications, hemofiltration via PS membranes is recommended to reduce plasma hirudin concentration. Hirudin dosage should be adapted not only to the clinical situation but also to the hirudin-sieving characteristics of the assigned dialyzer.

In vitro and in vivo evaluation of enoxaparin removal by continuous renal replacement therapies with acrylonitrile and polysulfone membranes

BACKGROUND

Enoxaparin is a low-molecular-weight heparin for which the degree of elimination through hemofilters during continuous renal replacement therapy (CRRT) is not well established.

OBJECTIVE

The elimination of enoxaparin by CRRT, using acrylonitrile (AN69) or polysulfone (PS) membranes, was studied in vitro and among critically ill patients.

METHODS

In vitro procedures were carried out using Ringer's lactate, bovine albumin-containing Ringer's lactate, or fresh human plasma as enoxaparin vehicle, using AN69 or PS membranes, and following continuous veno-venous hemofiltration (CVVH) or continuous veno-venous hemodialysis (CVVHD). Prefilter and ultrafiltrate samples were collected over 60 minutes. All procedures were carried out in triplicate. Patients undergoing CRRT entered the in vivo study. Enoxaparin was administered subcutaneously once daily. The sieving coefficient (Sc) and saturation coefficient (Sa) were calculated as the relation between anti-factor Xa activity in simultaneously collected dialysate/ultrafiltrate samples and plasma samples.

RESULTS

Mean Sc (for CVVH) or Sa (for CVVHD) values in the in vitro procedures ranged from 0.16 to 0.57. Sc values during CVVH were significantly higher than Sa values during CVVHD in the Ringer's lactate procedures for both membranes (AN69 membrane, P = 0.014; PS membrane, P < 0.001) and in the plasma procedures with the PS membrane (P < 0.001). Six male and 2 female patients (all white) participated in the in vivo study. Their mean body weight ranged from 55 to 80 kg, and their age ranged from 71 to 82 years. In patients, Sc or Sa achieved values between 0.26 and 0.67. No significant differences were found in vivo in the permeability of the 2 membranes to enoxaparin.

CONCLUSIONS

In these studies, the Sc and Sa values suggested that enoxaparin passed through AN69 and PS membranes during CRRT. Further pharmacokinetic and clinical studies are needed to determine whether a dose adjustment for enoxaparin is needed for patients undergoing CRRT.

HEMATOLOGY: ISSUES IN THE DIALYSIS PATIENT: The Safety of Heparins in End-Stage Renal Disease

In patients on chronic dialysis, unfractionated heparin (UFH) is the most commonly used agent for anticoagulation of the hemodialysis extracorporeal circuit, for hemodialysis catheter "locking" between dialysis treatments, and for nondialysis indications such as venous thromboembolic disease, peripheral vascular disease, and acute coronary artery disease. Potentially serious complications of UFH, such as hemorrhage, osteoporosis, and thrombocytopenia, have led to consideration of other options for anticoagulation, including low molecular weight heparin (LMWH) and direct thrombin inhibitors (DTIs). LMWH can be used for anticoagulation of the hemodialysis circuit, but whether this has significant benefit compared to UFH remains to be proven. Because of the somewhat unpredictable risk of severe bleeding complications when LMWH is used for other indications in dialysis patients, UFH rather than LMWH is preferred for treatment of thromboembolic disease in these patients. DTIs have been used for anticoagulation in dialysis patients with heparin-induced thrombocytopenia (HIT), with argatroban being the preferred agent if heparin-free hemodialysis cannot be performed. UFH still remains the preferred anticoagulant in the vast majority of dialysis patients requiring systemic anticoagulation and for anticoagulation of the extracorporeal hemodialysis circuit.

Use of bivalirudin, a direct thrombin inhibitor, and its reversal with modified ultrafiltration during heart transplantation in a patient with heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an increasingly common clinical finding in patients presenting for cardiac transplantation. Bivalrudin, a reversible direct thrombin inhibitor, is a molecular anti-coagulant with short half-life and the potential for removal by intraoperative hemofiltration. Herein we describe the dosing and intraoperative management of bivalrudin anti-coagulation in a patient undergoing urgent cardiac transplantation in the context of recently diagnosed HIT.

Direct thrombin inhibitors: pharmacology and clinical relevance

Although heparin has been a cornerstone of treatment for the prevention of thrombosis, it is limited by its adverse effects and unpredictable bioavailability. Direct thrombin inhibitors are a novel class of drugs that have been developed as an effective alternative mode of anticoagulation in patients who suffer from heparin-induced thrombocytopaenia, and for the management of thromboembolic disorders and acute coronary syndromes. The main disadvantages of the direct thrombin inhibitors are the lack of an antidote or readily available clinical monitoring. The mechanism of action, the properties of direct thrombin inhibitors and their potential to replace currently available anticoagulants are reviewed.

Thoughts and Progress. Protracted Bleeding After Hirudin Anticoagulation for Cardiac Surgery in a Patient With HIT II and Chronic Renal Failure

Heparin-induced thrombocytopenia type II (HIT II) requires alternative anticoagulation. Hirudin has been effectively used in patients with HIT II scheduled for cardiac surgery. However, bleeding complications were observed in patients with renal impairment. In vitro hemodialysis (HD) has been questioned over its efficacy in eliminating hirudin. Another approach to stop bleeding is the application of recombinant factor VIIa (rFVIIa). We report on a patient with HIT II and chronic renal failure who suffered from severe hirudin-induced bleeding after cardiac surgery who was safely treated with a combined approach of surgical hemostasis, substitution of blood products, HD, and rFVIIa to stop finally bleeding.

Alternatives to Heparin Infusion

This article offers an overview of the pathophysiology, diagnosis, and treatment of heparin-induced thrombocytopenia (HIT). This disorder is an immune-mediated reduction of platelets with subsequently increased generation of thrombin and increased risk of arterial and venous thrombosis. Heparin-induced thrombocytopenia can occur as an isolated incident or with acute thrombosis (HIT with thrombosis syndrome [HITTS]). Proper recognition, cessation of all forms of heparin (and compounds that cross-react with heparin), and rapid initiation of nonheparin anticoagulation are essential steps in reducing the risk of death, limb amputation, and new thrombotic events. Current alternatives to heparin are reviewed.

Managing Complications of Anticoagulant Therapy

Understanding the frequency, risk factors, and management of anticoagulant-induced adverse events will assist clinicians in optimizing patient outcomes. The most frequent adverse event of all anticoagulants is major bleeding. Risk factors for major bleeding have been identified with the heparin compounds, the direct thrombin inhibitors (DTIs), fondaparinux, and warfarin therapy. Understanding these risk factors can help prevent bleeding events. For cases of clinically significant bleeding, reversal agents exist primarily for heparin and warfarin. Although less common, nonbleeding adverse events of anticoagulant therapy can also be life threatening. The heparin compounds are associated with the development of heparin-induced thrombocytopenia (HIT) and osteoporosis. HIT can result in life-threatening thrombosis and is usually managed with a DTI. Nonbleeding adverse events with warfarin therapy include skin reactions and the development of venous limb gangrene. Appropriate initiation of warfarin therapy may decrease the risk of venous limb gangrene.

Argatroban dosing in intensive care patients with acute renal failure and liver dysfunction

STUDY OBJECTIVE

To demonstrate dosing adjustment difficulties of argatroban encountered in critically ill patients with acute liver dysfunction who are receiving continuous renal replacement therapy.

DESIGN

Case description.

SETTING

Medical and surgical intensive care unit in a tertiary care, university-affiliated hospital.

PATIENTS

Four consecutive patients with proven heparin-induced thrombocytopenia (HIT), acute renal failure requiring continuous renal replacement therapy, and various levels of transient hepatic impairment.

INTERVENTION

Argatroban, a direct synthetic thrombin inhibitor, was given continuously and stabilized at 0.125-0.85 microg/kg/minute to attain an activated partial thromboplastin time (aPTT) 1.5-2.5 times the normal value for periods of 6-36 days.

MEASUREMENTS AND RESULTS

Argatroban was started at the usual dosage of 2 microg/kg/minute, which resulted in significant overshooting of the aPTT and international normalized ratio (INR). No patient experienced bleeding or thrombotic complications. All patients were stabilized with reduced dosages such as those recommended for patients with chronic hepatic impairment.

CONCLUSION

We recommend argatroban therapy for intensive care patients with HIT, especially those with renal failure. However, in all patients with suspected liver dysfunction due to recent elevation of liver transaminase levels and combined renal failure, a decrease in the initial dosage and careful titration of the infusion are mandatory. Further studies are needed to fully elucidate argatroban elimination and dosage adjustments for intensive care patients.

Reversal of Direct Thrombin Inhibition After Cardiopulmonary Bypass in a Patient with Heparin-Induced Thrombocytopenia

We treated persistent hemorrhage after cardiopulmonary bypass in a heart transplant recipient who had received anticoagulation with the direct thrombin inhibitor bivalirudin by a combination therapy aimed at reducing the plasma concentration of the thrombin antagonist (hemodialysis and modified ultrafiltration), increasing the concentration of thrombin at bleeding sites (recombinant factor VIIa), and increasing the plasma concentration of other coagulation factors (fresh frozen plasma and cryoprecipitate). The bleeding was controlled, and there was no thrombotic complication.

IMPLICATIONS

A combination of modified ultrafiltration, hemodialysis, and the administration of recombinant factor VIIa, fresh frozen plasma, and cryoprecipitate may reverse the anticoagulant effect of bivalirudin.

Pharmacotherapy of heparin- induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a life-and-limb threatening condition that is associated with the development of antibodies that activate platelets and the coagulation system in the presence of unfractionated heparin or low molecular weight heparin. The binding of antibody to heparin-PF-4 complexes can activate platelets, leading to an acute, often catastrophic, thrombotic diathesis. The most common laboratory finding is the development of thrombocytopenia 5 or more days after beginning heparin treatment, which occur in up to 1 - 5% of patients exposed to heparin, depending on type of heparin and indication for anticoagulation. The onset of thrombocytopenia can be immediate or delayed for several weeks after the exposure to heparin. Approximately 50 - 60% of patients who develop HIT manifest acute venous or arterial thrombosis and a significant percentage of these patients die or develop vascular gangrene of a limb that requires amputation. Given the severe sequelae associated with HIT, recognition and immediate medical management is essential. Treatment of a patient with HIT is complex, as there are several different anticoagulants now available which have been shown to be useful. Optimal management depends on each patient's individual clinical manifestations, as well as the need for ongoing anticoagulation therapy. No single agent or treatment approach can be considered to be 'standard practice' as very few clinical trials have been completed, compare different treatment options. The use of warfarin alone in a patient with HIT, must be avoided in order to avoid the possibility of further activating coagulation, which may hasten the development of venous limb gangrene. There are several different tests available that detect HIT antibodies and each has different sensitivity and specificity for HIT. In this review we discuss the epidemiology and natural history of HIT, risk factors associated with the development of HIT and the clinical and laboratory tests that aid in the diagnosis and treatment. Special emphasis is given to addressing the management of HIT in special populations, particularly patients with renal or liver disease, acute coronary syndromes, pregnancy, paediatrics and patients who require cardiopulmonary bypass surgery.

New Treatment Options for Heparin-Induced Thrombocytopenia

Heparin, in various forms, is used in a variety of conditions including prophylaxis and treatment of thromboembolic disorders. Although the most common adverse effect related to the use of heparin is bleeding, heparin-induced thrombocytopenia (HIT) can also occur. Two types of HIT exist, HIT type I and type II. HIT type I is a mild and self-limiting disease in which the patient’s platelet count may decrease slightly but will recover with continued treatment. This is in contrast to HIT type II, which may lead to potentially devastating complications. Patients with HIT type II are at increased risk for thromboembolic complications that are mediated through autoimmune reactions and therefore require anticoagulation with danaparoid or one of the direct thrombin inhibitors, including lepirudin, argatroban, or bivalirudin. Limited data are available on the use of these agents in special populations including patients who are pregnant or those undergoing procedures such as percutaneous coronary intervention, cardiopulmonary bypass and dialysis, and pregnancy. Future therapies may include the use of unfractionated heparin in combination with glycoprotein IIb/IIIa inhibitors during cardiopulmonary bypass.