A phase I, single and continuous dose administration study on the safety, tolerability, and pharmacokinetics of neorudin, a novel recombinant anticoagulant protein, in healthy subjects.

The aim of this study was to evaluate the tolerability, safety, and pharmacokinetics of single and continuous dose administration of recombinant neorudin (EPR-hirudin, EH) by intravenous administration in healthy subjects, and to provide a safe dosage range for phase II clinical research. Forty-four subjects received EH as a single dose of between 0.2 and 2.0 mg/kg by intravenous bolus and drip infusion. In addition, 18 healthy subjects were randomly divided into three dose groups (0.15, 0.30, and 0.45 mg/kg/h) with 6 subjects in each group for the continuous administration trial. Single or continuous doses of neorudin were generally well tolerated by healthy adult subjects. There were no serious adverse events (SAEs), and all adverse events (AEs) were mild to moderate. Moreover, no subjects withdrew from the trial because of AEs. There were no clinically relevant changes in physical examination results, clinical chemistry, urinalysis, or vital signs. The incidence of adverse events was not significantly related to drug dose or systemic exposure. After single-dose and continuous administration, the serum EH concentration reached its peak at 5 min, and the exposure increased with the increase in the administered dose. The mean half-life (T1/2 ), clearance (Cl), and apparent volume of distribution (Vd) of EH ranged from 1.7 to 2.5 h, 123.9 to 179.7 ml/h/kg, and 402.7 to 615.2 ml/kg, respectively. The demonstrated safety, tolerability, and pharmacokinetic characteristics of EH can be used to guide rational drug dosing and choose therapeutic regimens in subsequent clinical studies. Clinical trial registration: Chinadrugtrials.org identifier: CTR20160444.

Evaluation of intravenous direct thrombin inhibitor monitoring tests: Correlation with plasma concentrations and clinical outcomes in hospitalized patients.

The parenterally administered direct thrombin inhibitors (DTIs) argatroban and bivalirudin are effective anticoagulants for acute heparin-induced thrombocytopenia (HIT) treatment. The activated partial thromboplastin time (aPTT) has classically been used as the monitoring test to assess degree of anticoagulation, however concerns exist with using aPTT to monitor DTI therapy. In this observational study plasma samples from DTI treated patients were analyzed by aPTT, dilute thrombin time (dTT) and ecarin chromogenic assay (ECA) to delineate results into concordant and discordant groups. Discordant samples were further analyzed via liquid chromatography with tandem mass spectrometry (LC MS/MS). In total 101 patients with 198 samples were evaluated. Discordance between tests were frequent (59% of DTI treated patients). Bivalirudin aPTT vs dTT discordance was observed in 45% (57/126) of samples. Amongst bivalirudin samples with test discordance dTT results were more likely to be concordant with LC MS/MS than the aPTT (77% vs 9%, p < 0.0001). Argatroban aPTT vs dTT discordance was observed in 43% (31/72) and aPTT vs ECA discordance was observed in 40% (29/72) of samples. Amongst argatroban samples with test discordance both the dTT and ECA tests were more likely to have concordant results with LC MS/MS than the aPTT (88% vs 9%, p < 0.0001 for both dTT and ECA tests). There were no differences between discordant and concordant patient groups in a composite outcome of bleeding/thrombosis rate (23% vs 27%, p = 0.689). Further investigation is warranted to elucidate the effect of suitable monitoring assays on patient outcomes in the setting of DTI therapy.

Overcoming Heparin-Associated RT-qPCR Inhibition and Normalization Issues for microRNA Quantification in Patients with Acute Myocardial Infarction.

BACKGROUND: Cardiac-enriched micro ribonucleic acids (miRNAs) are released into the circulation following ST-elevation myocardial infarction (STEMI). Lack of standardized approaches for reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) data normalization and presence of RT-qPCR inhibitors (e.g. heparin) in patient blood samples have prevented reproducible miRNA quantification in this cohort and subsequent translation of these biomarkers to clinical practice. MATERIALS AND METHODS: Using a RT-qPCR miRNA screening platform, we identified and validated an endogenous circulating miRNA as a normalization control. In addition, we assessed the effects of in vivo and in vitro anticoagulant drugs administration (heparin and bivalirudin) on three RT-qPCR normalization strategies (global miRNA mean, exogenous spike-in control [cel-miR-39] and endogenous miRNA control). Finally, we evaluated the effect of heparin and its in vitro inhibition with heparinase on the quantification of cardiac-enriched miRNAs in STEMI patients. RESULTS: miR-425-5p was validated as an endogenous miRNA control. Heparin administration in vitro and in vivo inhibited all RT-qPCR normalization strategies. In contrast, bivalirudin had no effects on cel-miR-39 or miR-425-5p quantification. In vitro RNA sample treatment with 0.3 U of heparinase overcame heparin-induced over-estimation of cardiac-enriched miRNA levels and improved their correlation with high-sensitivity troponin T. CONCLUSION: miRNA quantification in STEMI patients receiving heparin is jeopardized by its effect on all RT-qPCR normalization approaches. Use of samples from bivalirudin-treated patients or in vitro treatment of heparin-contaminated samples with heparinase are suitable alternatives for miRNA quantification in this cohort. Finally, we reinforce the evidence that cardiac-enriched miRNAs early after myocardial reperfusion reflect the severity of cardiac injury.

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.

Development, validation, and clinical pharmacokinetic application of ultra-performance liquid chromatography/tandem mass spectrometry method for simultaneously determining a novel recombinant hirudin derivative (Neorudin) and its active metabolite in human serum.

Recombinant Neorudin (EPR-hirudin, EH), a novel, low-bleeding anticoagulant fusion protein, has been developed as an inactive prodrug that is converted to an active metabolite, hirudin variant 2-Lys47 (HV2), at the thrombus site and is undergoing Phase I clinical trials in China. The goal of our present research was to establish a novel ultra-performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) method for simultaneously quantifying EH and HV2 in human serum. Furthermore, the method was used in clinical pharmacokinetic study after validation. The stock and dilute working solutions were dissolved in methanol/water (1/1, v/v) to avoid their adsorption. The internal standard (IS) used, had a similar structure to that of EH. The serum sample pretreatment involved protein precipitation with methanol. The volume ratio of the precipitating solvent to the serum sample was 3:1 (300µL methanol: 100µL serum sample). The chromatographic separation was performed using a 300Å C18 column using a multi-step gradient with a mobile phase consisting of acetonitrile:water containing 0.1% formic acid. The detection was carried out using an ESI source in the positive multiple reaction monitoring (MRM) mode. The within and between run precision were in the range of 3.5%-10.3% for EH and 3.3%-8.8% for HV2, and the accuracy of both EH and HV2 was between -4.6% and 2.1%. The extraction recoveries and matrix effect at three quality control (QC) levels for EH and HV2 were satisfactory. The stabilities of EH and HV2 during the storage, preparation, and analysis were confirmed, and the carryover also proved to be acceptable. This technique was efficiently used in Phase I clinical pharmacokinetic trials of EH following intravenous administration of 0.2mg/kg to healthy volunteers.

Factibilidad del uso de bivalirudina como anticoagulante en soporte vital extracorpóreo / Experience with anticoagulation with bivalirudin during extracorporeal membrane oxygenation

Background: Extracorporeal membrane oxygenation (ECMO) is used with increasing frequency in patients with respiratory and cardiac failure. The achievement of an adequate anticoagulation is critical to avoid patient and circuit complications. Aim: To assess the feasibility and safety of anticoagulation with bivalirudin, as an alternative to unfractionated heparin (UFH), in patient with ECMO. Material and Methods: Observational study, which included all patients receiving anticoagulation with bivalirudin during ECMO, according to a standardized protocol, between august 2015 to May 2016. Results: Bivalirudin was used in 13 out 70 patients connected to ECMO. Ten procedures were for cardiac support and three for respiratory support. Mortality was 43%. ECMO lasted 31 ± 31 days. The time of UFH use before changing to bivalirudin was 7 ± 7 days. The reasons to change to bivalirudin were inadequate levels of partial thromboplastin time (PTT) in nine patients, and heparin induced thrombocytopenia (HIT) in four patients. The time of bivalirudin use was 24 ± 33 days. Per patient, a mean of 2.7 ± 4 oxygenators were changed. These had a useful life of 11.4 and 19.1 days during UFH and bivalirudin use, respectively. The mean bivalirudin dose was 0.08 ± 0.04 mg/kg/h. There was no significant bleeding, thrombosis or circuit obstruction during its use. PTT levels (p < 0.01) and platelet count (p < 0.01) increased significantly after the start of bivalirudin use in patients with UHF resistance and HIT, respectively. Conclusions: Bivalirudin was a safe and efficient drug for anticoagulation during ECMO. It is important to have an alternative drug for anticoagulation in ECMO patients.

A novel sequential electrostatic-HILIC SPE within a quantitative method for bivalirudin in human plasma by LC-SRM.

AIM: This work set out to realize an idea for a novel means of extracting the peptide therapeutic bivalirudin from human plasma in what would be a uniquely selective means of SPE, a mixed-mode protocol involving electrostatic interactions followed by HILIC. RESULTS: Inter and intra-assay relative error ranged from 3.52 to 8.23%, and 2.37 to 6.90%, respectively. Inter and intra-assay precision ranged from 2.64 to 7.12%, and 0.855 to 2.90%, respectively. Recoveries of 80% were attained, and there was no hint of discernible manifestation of matrix effects. CONCLUSION: The method was shown to perform excellently in the assessment tantamount to method validation. The essence of the extraction method presents a new option for highly selective extraction of peptides from biological matrices.

UNBLOCK: an open-label, dose-finding, pharmacokinetic and safety study of bivalirudin in children with deep vein thrombosis.

BACKGROUND: Direct thrombin inhibitors offer potential advantages over unfractionated heparin but have been poorly studied in children. OBJECTIVES: To determine appropriate dosing of bivalirudin in children and adolescents and the relationship between activated partial thromboplastin time (APTT) and plasma bivalirudin concentration. PATIENTS/METHODS: The UNBLOCK (UtilizatioN of BivaLirudin On Clots in Kids) study was an open-label, single-arm, dose-finding, pharmacokinetic, safety and efficacy study of bivalirudin for the acute treatment of deep vein thrombosis (DVT) in children aged 6 months to 18 years. Drug initiation consisted of a bolus dose (0.125 mg kg(-1) ) followed by continuous infusion (0.125 mg kg h(-1) ). Dose adjustments were based on the APTT, targeting a range of 1.5-2.5 times each patient's baseline APTT. Safety was assessed by specific bleeding endpoints and efficacy by repeat imaging at 48-72 h and 25-35 days. RESULTS: Eighteen patients completed the study. Following the bolus dose and the initial infusion rate, most patients' APTT values were within the target range. The infusion rate bivalirudin correlated more closely with drug concentration than the APTT. At 48-72 h, nine (50%) patients had complete or partial thrombus resolution, increasing to 16 (89%) at 25-35 days. No major and one minor bleeding event occurred. CONCLUSIONS: Bivalirudin demonstrated reassuring safety and noteworthy efficacy in terms of early clot resolution in children and adolescents with DVT. Although a widely available and familiar monitoring tool, the APTT correlates poorly with plasma bivalirudin concentration, possibly limiting its utility in managing pediatric patients receiving bivalirudin for DVT.

Label-free fluorescent detection of thrombin activity based on a recombinant enhanced green fluorescence protein and nickel ions immobilized nitrilotriacetic acid-coated magnetic nanoparticles.

Herein, a novel label-free fluorescent assay has been developed to detect the activity of thrombin and its inhibitor, based on a recombinant enhanced green fluorescence protein (EGFP) and Ni(2+) ions immobilized nitrilotriacetic acid-coated magnetic nanoparticles (Ni(2+)-NTA MNPs). The EGFP, containing a thrombin cleavage site and a hexahistidine sequence (His-tag) at its N-terminal, was adsorbed onto Ni(2+)-NTA MNPs through Ni(2+)-hexahistidine interaction, and dragged out of the solution by magnetic separation. Thrombin can selectively digest EGFP accompanied by His-tag peptide sequence leaving, and the resulting EGFP cannot be captured by Ni(2+)-NTA MNPs and kept in supernatant. Hence the fluorescence change of supernatant can clearly represent the activity of thrombin. Under optimized conditions, such assay showed a relatively low detection limit (3.0×10(-4) U mL(-1)), and was also used to detect the thrombin inhibitor, Hirudin, and further applied to detect thrombin activity in serum. Combined with the satisfactory reusability of Ni(2+)-NTA MNPs, our method presents a promising candidate for simple, sensitive, and cost-saving protease activity detecting and inhibitor screening.

Development and validation of a highly sensitive LC-MS/MS method for quantitation of bivalirudin in human plasma: application to a human pharmacokinetic study.

A sensitive, specific and simple LC-MS/MS method was developed for the identification and quantification of bivalirudin in human plasma using diazepam as an internal standard (IS). The API-4000 LC-MS/MS was operated under multiple-reaction monitoring mode using electrospray ionization. The sample preparation consisted of an easy protein precipitation sample pretreatment with methanol. Chromatographic separation was achieved on a Zorbax Eclipse plus C18 100 × 2.1 mm column with a mobile phase of water-methanol-0.1% formic acid. The analytes were detected with a triple quadrupole Quantum Access with positive ionization. Ions monitored in the multiple-reaction monitoring mode were m/z 1091 → 650 for bivalirudin (at 2.70 min) and m/z 285 → 193 for diazepam (at 3.85 min). The developed method was validated in human plasma with a lower limit of quantitation of 20 µg/L for bivalirudin. A linear response function was established for the range of concentrations 20-10,000 µg/L (r > 0.998) for bivalirudin. The intra- and inter-day precision values for bivalirudin met the acceptance criteria as per US Food and Drug Administration guidelines. Bivalirudin was stable in the battery of stability studies, viz. bench-top, freeze-thaw cycles and long-term stability. The developed assay method was applied to an intravenous administration study in humans.

Pharmacokinetics study of recombinant hirudin in the plasma of rats using chromogenic substrate, ELISA, and radioisotope assays.

AIM: To compare the analytical methods used to study the pharmacokinetics of recombinant hirudin in the plasma of rats that had been injected with (125)I-recombinant hirudin. METHODS: 2.0 mg/kg (125)I-recombinant hirudin were injected intravenously into rats. The recombinant hirudins in the plasma was analyzed by chromogenic substrate assay, enzyme-linked immunosorbent assay (ELISA), total radioisotope assay (RA) and trichloroacetic acid pre-treated total radioisotope assay (TCA-RA). RESULTS: The chromogenic substrate assay standard curve was linear over the concentration range from 3.12 to 40.00 ng/ml for the recombinant hirudin in plasma. The relative standard deviations (RSD) for the intra- and inter-day variation were 5.0 to 6.3% and 11.9 to 12.6%, respectively. The recoveries of recombinant hirudin was 89.8% to 100.7%. The limit of quantification (LOQ) was 3.12 ng/ml. The concentration-time curve of the recombinant hirudin in the plasma could be explained as a two-compartment model. Pharmacokinetic parameters, including the half-life of distribution phase (t1/2 α), the half-life of elimination phase (t1/2 ß), volume of apparent distribution (Vd), and area under the concentration-time curve from zero to infinite time (AUC0-t) were 7.59 min, 46.99 min, 0.17 L/kg, and 204.5 mg/L/min, respectively, as determined by chromogenic substrate assay; 6.41 min, 47.28 min, 1.24 L/kg, and 575.18 mg/L/min, respectively, as determined by ELISA; 3.69 min, 701.90 min, 0.04 L/kg, and 4189 mg/L/min, respectively as determined by RA; and 4.57 min, 724.9 min, 0.09 L/kg, and 2329 mg/L/min, respectively, as determined by TCA-RA. CONCLUSIONS: The chromogenic substrate assay on the concentration dynamics of the recombinant hirudin in the plasma is a specific, sensitive, and accurate analytical method for pharmacokinetic studies. Moreover, the pharmacokinetic parameters determined by the chromogenic substrate assay and ELISA are congruent except for AUC.

Prediction of drug concentration-time profiles of therapeutic proteins in humans from animals.

The main objective of this work is to evaluate two methods to predict concentration-time profiles of therapeutic proteins in humans in a multi-compartment system using animal pharmacokinetic parameters. The prediction of concentration-time profiles in humans in a multi-compartment system was based on two proposed methods (volumes of distribution and pharmacokinetic constants) of Mordenti. Seven protein drugs (5 monoclonal antibodies, one epoetin, and one thrombin inhibitor) from the literature were chosen that were described by two-compartment model in both humans and animals. Two- compartment model parameters (CL, V(c), V(ss), V(ß), α, A, ß and B) at least from 3 animals were scaled to humans and then were used to predict plasma concentrations-time profiles in humans. The results showed that both the methods provided almost similar concentration-time profiles for most of the drugs. It appears that the proposed methods of Mordenti can be used for reasonably accurate prediction of concentration-time profiles of therapeutic proteins in humans.

Disseminated intravascular coagulation does not play a major role in the pathogenesis of classical swine fever.

Classical swine fever (CSF) is a multi-systemic disease that can be accompanied by severe haemorrhagic lesions. The underlying pathogenetic mechanisms are still far from being understood, though disseminated intravascular coagulation (DIC) was discussed as a major factor. In the presented study, the direct thrombin inhibitor hirudin was used in an attempt to elucidate the role of the coagulation system in the pathogenesis of CSF-induced haemorrhagic lesions. Two groups of piglets (n=5) were infected with highly virulent CSF virus (CSFV) strain CSF0634. One group underwent daily treatment with hirudin, the other served as untreated challenge infection control. Assessment of clinical signs using a clinical score system, coagulation tests, and blood counts were performed daily. Both groups developed acute-lethal CSF with haemorrhagic lesions. Although changes in the coagulation system were seen in the late stages of CSFV infection, our results strongly suggest that DIC does not present the crucial event in the pathogenesis of haemorrhagic lesions.

Comparison of bivalirudin dosing strategies using total, adjusted, and ideal body weights in obese patients with heparin-induced thrombocytopenia.

STUDY OBJECTIVES: To compare dosing strategies using total body weight (actual measured body weight), adjusted body weight, and ideal body weight when starting bivalirudin for the treatment for heparin-induced thrombocytopenia (HIT) in obese patients, and to compare differences in dosing requirements and clinical outcomes between obese and nonobese patients. DESIGN: Retrospective medical record review. SETTING: Academic tertiary care medical center. PATIENTS: One hundred thirty-five medical and surgical patients who were treated with bivalirudin for HIT between June 1, 2004, and October 1, 2009. MEASUREMENTS AND MAIN RESULTS: The 135 patients were separated into two groups based on body mass index (BMI): 46 patients had a BMI greater than 30 kg/m(2) and were classified in the obese group; the nonobese group consisted of 89 patients with a BMI less than 30 kg/m(2) . The mean BMI in the obese group was 37.7 kg/m(2) (range: 30.1-56.2 kg/m(2) ). Weight-standardized doses that achieved activated partial thromboplastin time (aPTT) goal were compared in the obese group. The mean ± SD doses that achieved aPTT goal with total (actual), adjusted, and ideal body weights in this group were 0.1 ± 0.07, 0.11 ± 0.08, and 0.14 ± 0.09 mg/kg/hour, respectively. Of the three weight-based dosing approaches, total body weight followed by adjusted body weight provided the closest correlation to rates observed at the target aPTT goal. The secondary analysis compared initial doses of bivalirudin, doses required to reach goal aPTT, time to achieve goal aPTT, and clinical outcomes (number of patients not achieving goal, new thrombosis, major bleeding, and 30-day all-cause mortality) between the obese and nonobese groups. A significant difference in initial dose was noted between groups; however, no significant differences in dose required to achieve goal aPTT, time to achieve goal aPTT, and clinical outcomes were noted between the obese and nonobese groups. CONCLUSION: This study provides evidence that the dosing strategy for bivalirudin based on total body weight is the most accurate predictor of achieving aPTT goal in obese patients with HIT. The study also suggests that there are no clinical differences that warrant different dosing strategies between obese and nonobese patients. Further prospective studies are needed to confirm these findings.

Pharmacokinetics, pharmacodynamics, tolerability and safety of single doses of bivalirudin in healthy chinese subjects.

The objectives of the present study were to assess pharmacokinetics, pharmacodynamics, tolerability and safety of intravenous administration of bivalirudin, a direct thrombin inhibitor, in healthy Chinese subjects. 48 subjects were equally divided into 4 groups (0.5 mg/kg, 0.75 mg/kg, 1.05 mg/kg intravenous bolus, and 0.75 mg/kg intravenous bolus followed by an infusion of 1.75 mg/kg per hour for 4 h) by a randomized, single-blind and placebo-controlled (bivalirudin groups: n=9/group; placebo groups: n=3/group) design. The safety observations showed that bivalirudin was well tolerated in the studied dose range, all adverse events were mild in severity. The half-life of bivalirudin was approximately 0.57 h (34 min), exposure increased in a dose-dependent manner. In group receiving a 0.75 mg/kg intravenous bolus followed by 1.75 mg/kg per hour infusion for 4 h, bivalirudin concentrations remained at 5000-5500 µg/l within the 4 h infusion period, which was similar to the reported data of Caucasian patients and can provide the desired anticoagulant effects. There was a strong correlation between bivalirudin concentration and anticoagulant effect. A Sigmoid model was used to fit the pharmacodynamic parameters activated clotting time (ACT), activated partial thromboplastin time (APTT) and prothrombin time (PT) and bivalirudin concentrations. The findings of this study suggest that the same dosing regimens of bivalirudin may be administered to Chinese and Caucasian patients. Ongoing and future studies in large populations may add further information.

Lepirudin dose-dependently increases thrombelastography parameters at therapeutic plasma concentrations as measured with ROTEM® - a pilot study.

BACKGROUND: The aim of this in-vitro pilot study was to assess the usefulness of the thrombelastograph ROTEM® for determining the anticoagulant activity of lepirudin. METHODS: The ROTEM® parameters, clotting-time, clot formation time and maximum clot firmness were measured in the presence of increasing concentrations of lepirudin (10-4 µg/ml - 10 µg/ml). Citrated blood was obtained from 16 healthy male subjects. RESULTS: Clotting-time increased from 79.1 ± 53.4 s at baseline to 194.1 ± 151.9 s at a drug concentration of 1µg/ml as measured with EXTEM (p < 0.0001). Borderline significance was found for the difference between maximum clot firmness at baseline (60.2 ± 4.3 mm) and after drug application (55.5 ± 6.5 mm). CONCLUSIONS: This pilot investigation shows that the ROTEM® device may be suitable for monitoring lepirudin at low concentrations but the results should be confirmed in a larger study and the ROTEM® device validated against standard methods.

Successful use of hirudin during cardiac surgery using minimized extracorporeal circulation in patients with heparin-induced thrombocytopenia.

In this case series, we describe our successful use of a reduced hirudin dosage as an anticoagulant during cardiac surgery using minimized extracorporeal circulation in patients with heparin-induced thrombocytopenia.

Pediatric catheterization laboratory anticoagulation with bivalirudin.

BACKGROUND: Pediatric physicians regularly face the problem of uncertain procedural anticoagulation in children, especially in neonates. We sought to evaluate the safety, plasma concentration (pharmacokinetics, PK), pharmacodynamics (PD), and dosing guidelines of bivalirudin when used as a procedural anticoagulant in pediatric percutaneous intravascular procedures. METHODS AND RESULTS: Pediatric subjects undergoing percutaneous intravascular procedures for congenital heart disease were enrolled and received the current weight-based dose used in percutaneous coronary interventions (0.75 mg/kg bolus, 1.75 mg/kg/hr infusion). Blood samples for PK/PD analyses were drawn, and safety was evaluated by monitoring bleeding and thrombosis events. A total of 110 patients (11 neonates, 33 infants, 32 young children, and 34 older children) were enrolled; 106 patients received the protocol dose. The PK/PD response of bivalirudin was predictable and behaved in a manner similar to that in adults. Weight-normalized bivalirudin clearance rates were more rapid in neonates and decreased with increasing age. Bivalirudin concentrations were slightly lower in neonates, with a trend to an increase with age. Activating clotting time response was consistent with adult studies and prolonged in all age groups, and there was reasonable correlation between activating clotting time and bivalirudin plasma concentrations across all age groups. There were few major bleeding (2 of 110, 1.8%) or thrombotic events (9 of 110, 8.2%) reported. CONCLUSIONS: PK/PD response of bivalirudin in the pediatric population is predictable and behaves in a manner similar to that in adults. Using adult dosing, bivalirudin safely provided the expected anticoagulant effect in the pediatric population undergoing intravascular procedures for congenital heart disease.