Recombinant Hirudin Research Articles

Formulation of sustained release aqueous Zn–hirudin suspensions

Sustained release formulations for recombinant hirudin (rHir), an anticoagulant thrombin-specific inhibitor, were developed. Zn–rHir suspensions were formed by precipitation with zinc salts at neutral pH. Characterization of protein precipitation was by UV analysis, capillary electrophoresis (CE), zinc analysis, light and electron microscopy, and particle size analysis. The precipitation of aqueous rHir solution with ZnCl 2 solution at neutral pH resulted in Zn–rHir suspensions. Optimum yields of pelletized Zn–rHir were obtained between pH 7.0 and 7.4. For complete precipitation (∼100%) a molar ratio of zinc to rHir of >28 was necessary. As shown by electron microscopy, the smallest resolvable unit of Zn–rHir suspensions was 20 nm. Agglomerates of up to 200 μm were observed by light microscopy. Zinc salt-induced precipitation phenomena were also investigated using ZnBr 2, ZnI 2, Zn(NO 3) 2 and ZnSO 4 instead of ZnCl 2. ZnSO 4 showed the lowest precipitation efficiency. All other salts behaved similar to ZnCl 2. Upon storage the pelletized protein content of the ZnCl 2 based precipitates was stable (∼95% rHir after 1 year at room temperature), whereas the pelletized protein content of ZnSO 4 based precipitates dropped sharply after precipitation (2% remaining after 13 days at room temperature). This indicates a transition of the ZnSO 4 based precipitates to hexagonal basic zinc sulfate plates and free rHir. The driving force is the lower aqueous solubility of basic zinc sulfate as compared to the higher solubility of basic zinc chloride.

New frontiers in deep vein thrombosis management: Conclusions

T HIS SYMPOSIUM investigated the new frontiers in venous thromboprophylaxis facing the vascular physician as we approach the end of the 1990s. Key issues discussed included risk assessment and management of medical patients, high-risk surgery and neurosurgery patients, and the advent of desirudin, a new, highly efficacious antithrombotic agent. It is clear that venous thromboembolism (VTE) is a problem in nonsurgical patients. Indeed, the majority of deaths seen in hospitalized patients due to pulmonary embolism occur in medical patients. Professor Harenberg noted that there are no risk assessment models (RAMS) that stratify nonsurgical patients into risk groups, and there is no consensus on what thromboprophylactic measures are required for them. The limited number of protocols completed to date have examined heterogeneous patient populations and employed a range of methods to detect VTE. Dr Cohen emphasized the need for studies in specific, homogeneous medical patient groups to investigate the most appropriate prophylaxis and highlighted the MEDENOX trial. The MEDENOX (MEDical patients and ENOXaparin) study, which enrolled more than 1,100 medical patients, provides unique insight into the actual risk of VTE in heart failure, acute respiratory disease, and acute infectious disease patients, and reveals the potential benefits of treatment with once-daily enoxaparin, 20 mg or 40 mg. Despite the high efficacy of low-molecularweight heparins (LMWHs) in the prevention of VTE in orthopedic surgery patients, the rates of deep vein thrombosis (DVT) observed still show that certain patients remain at additional risk of VTE. Of the new agents investigated during the 1990s the recombinant hirudin, desirudin, has been shown to provide excellent thromboprophylactic cover to orthopedic surgery patients, and is now approved within the European Union. Professor Eriksson described the clinical trial program recently completed for desirudin, which demonstrated its superior efficacy over unfractionated heparin (UFH) in high-risk orthopedic surgery patients. Professor Eriksson also pointed out that despite the high efficacy seen with the LMWH enoxaparin, desirudin offered further DVT protection, with no increased risk of bleeding. Professor Samama highlighted the importance of risk stratification in surgical patients. RAMS help predict the likelihood of VTE, but further RAMS are required, especially for the identification of patients at high risk of VTE. Additional measures including the use of novel agents may prove worthwhile in these high-risk patients. Neurosurgery carries a high risk of VTE. Limited data are currently available. Mechanical methods of thromboprophylaxis, such as graduated compression stockings, have been shown to be effective in neurosurgical patients. Although recent trials have shown that LMWHs provide safe and effective prophylaxis in patients undergoing neurosurgical procedures, the incidence of VTE remains high. Dr Nurmohamed emphasized that more trials with a greater number of patients to investigate the most appropriate prophylaxis for these patients should be initiated. The optimal duration of thromboprophylaxis has been a focus of discussion for some time. Economic pressures are leading to shorter hos-

Management of urgent high-risk cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and coexisting disorders of renal function: Use of heparin and epoprostenol combined with on-line monitoring of platelet function

HEPARIN-INDUCED THROMBOCYTOPENIA TYPE II (HIT II) is an immunologic life-threatening condition that causes stroke, myocardial or mesenteric infarction, or thromboembolism in the lungs or extremities. 1 Shorten GD Comunale ME Heparin-induced thrombocytopenia. J Cardiothorac Vasc Anesth. 1996; 10: 521-530 Abstract Full Text PDF PubMed Scopus (36) Google Scholar , 2 Slaughter TF Greenberg CS Heparin-associated thrombocytopenia and thrombosis: Implications for perioperative management. Anesthesiology. 1997; 87: 667-675 Crossref PubMed Scopus (46) Google Scholar , 3 Bauer TL Arepaly G Konkele BA Prevalence of heparin-associated antibodies without thrombosis in patients undergoing cardiopulmonary bypass surgery. Circulation. 1997; 95: 1242-1246 Crossref PubMed Scopus (284) Google Scholar It is prudent that heparin not be administered in any form whenever possible. This recommendation poses a problem in patients being prepared for cardiopulmonary bypass (CPB). Suitable alternatives for heparin-free anticoagulation include defibrinogenation (ancrod); the synthetic heparinoid, orgaran; or the antithrombin, hirudin. 4 Koster A Kuppe H Hetzer R et al. Emergent cardiopulmonary bypass in five patients with heparin-induced thrombocytopenia type II employing recombinant hirudin. Anesthesiology. 1998; 89: 777-780 Crossref PubMed Scopus (68) Google Scholar , 5 Koster A Kuppe H Mertzlufft F Cardiopulmonary bypass with recombinant hirudin in patients with heparin-induced thrombocytopenia type II: A synopsis of 19 cases. Br J Anaesth. 1999; 82: A116 Google Scholar Recombinant hirudin (r-hirudin) has gained a pivotal role because of relevant advantages 4 Koster A Kuppe H Hetzer R et al. Emergent cardiopulmonary bypass in five patients with heparin-induced thrombocytopenia type II employing recombinant hirudin. Anesthesiology. 1998; 89: 777-780 Crossref PubMed Scopus (68) Google Scholar , 5 Koster A Kuppe H Mertzlufft F Cardiopulmonary bypass with recombinant hirudin in patients with heparin-induced thrombocytopenia type II: A synopsis of 19 cases. Br J Anaesth. 1999; 82: A116 Google Scholar , 6 Greinacher A Völpel H Janssens U et al. Recombinant hirudin (lepirudin) provides safe and effective anticoagulation in patients with heparin-induced thrombocytopenia: A prospective study. Circulation. 1999; 99: 73-80 Crossref PubMed Scopus (505) Google Scholar (eg, rapid onset, short half-life, and availability of reliable on-line monitoring). If, however, urgent CPB is required in patients with coexisting renal impairment, r-hirudin (as well as the other options) may involve considerable disadvantages, 4 Koster A Kuppe H Hetzer R et al. Emergent cardiopulmonary bypass in five patients with heparin-induced thrombocytopenia type II employing recombinant hirudin. Anesthesiology. 1998; 89: 777-780 Crossref PubMed Scopus (68) Google Scholar , 5 Koster A Kuppe H Mertzlufft F Cardiopulmonary bypass with recombinant hirudin in patients with heparin-induced thrombocytopenia type II: A synopsis of 19 cases. Br J Anaesth. 1999; 82: A116 Google Scholar which include the lack of an antidote 4 Koster A Kuppe H Hetzer R et al. Emergent cardiopulmonary bypass in five patients with heparin-induced thrombocytopenia type II employing recombinant hirudin. Anesthesiology. 1998; 89: 777-780 Crossref PubMed Scopus (68) Google Scholar , 6 Greinacher A Völpel H Janssens U et al. Recombinant hirudin (lepirudin) provides safe and effective anticoagulation in patients with heparin-induced thrombocytopenia: A prospective study. Circulation. 1999; 99: 73-80 Crossref PubMed Scopus (505) Google Scholar and a prolonged pharmacologic effect resulting from sustained renal elimination. 5 Koster A Kuppe H Mertzlufft F Cardiopulmonary bypass with recombinant hirudin in patients with heparin-induced thrombocytopenia type II: A synopsis of 19 cases. Br J Anaesth. 1999; 82: A116 Google Scholar

A quick assay for monitoring recombinant hirudin during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type IIAdaptation of the ecarin clotting time to the Act II device

Background: Recombinant hirudin is increasingly advocated as a promising alternative anticoagulation for patients with heparin-induced thrombocytopenia type II during cardiopulmonary bypass. This requires monitoring of the ecarin clotting time. No commercial ecarin clotting time assay is available for clinical use. We adapted the ecarin clotting time to the easy-to-handle ACT II device. Methods: Three different concentrations of the ecarin reagent (20, 10, 5 U/mL) were investigated as preliminary studies. Standard calibration curves were constructed for concentrations of recombinant hirudin ranging from 0 to 5 μg/mL. In vivo samples were collected from patients with heparin-induced thrombocytopenia type II who underwent cardiopulmonary bypass, and the values were compared with the values obtained by the chromogenic method. The final concentration for the assay of 5 IU/mL ecarin was further assessed in vitro for reproducibility and the influence of variations in hematocrit, platelet count, and procoagulants. Results: All three concentrations of ecarin revealed linearity to 5 μg/mL concentrations of recombinant hirudin. The ecarin concentration of 5 U/mL revealed the best correlation (0.87) to the laboratory method, was reproducible over the whole recombinant hirudin range, and was not influenced by the variations in the in vitro setup. Conclusions: The ACT II/ecarin clotting time with an ecarin concentration of 5 U/mL is a simple and reliable assay for monitoring recombinant hirudin during cardiopulmonary bypass. Use of this assay allows a wider use of recombinant hirudin in patients with heparin-induced thrombocytopenia type II during bypass and thereby may contribute to the safer management of these patients. (J Thorac Cardiovasc Surg 2000;119:1278-83)

Recombinant hirudin as an alternative for anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II: A 1-year experience in 57 patients

Objective To explore the possible use of recombinant hirudin (r-hirudin) as an alternative to heparin for anticoagulation during cardiovascular surgery.Design Retrospective analysis.Setting Two university hospitals.Participants Fifty-seven patients with heparin-induced thrombocytopenia type II (HIT II) in whom r-hirudin was used during cardiovascular surgery with cardiopulmonary bypass (CPB).Interventions None.Measurements and Main Results The r-hirudin concentration was monitored on-line, at the point of the patient's care using the ecarin clotting time and maintained in the range of 3 to 4 μg/mL. The r-hirudin elimination at the conclusion of CPB was augmented through modified zero-balanced ultrafiltration and forced diuresis. The duration of CPB was 63 to 246 minutes. The r-hirudin requirement per minute of CPB was 0.016 to 0.035 μg/kg/min, and the 24-hour blood drainage was 50 to 2,200 mL. Of the 57 patients, 54 fully recovered, including 9 patients who did not require any allogenic products. Four patients, all with impaired renal function, showed prolonged r-hirudin elimination and excessive bleeding and required surgical reexploration. Three patients died as a result of complications unrelated to the perioperative management.Conclusion This study provides evidence that r-hirudin can be used safely and effectively for routine anticoagulation during CPB in patients diagnosed with HIT II. Almost 95% of the patients in whom it was used were discharged uneventfully. Patients with perioperative renal failure, however, showed increased bleeding.

Recombinant hirudin as an alternative for anticoagulation during cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II: A 1-year experience in 57 patients

To explore the possible use of recombinant hirudin (r-hirudin) as an alternative to heparin for anticoagulation during cardiovascular surgery. Retrospective analysis. Two university hospitals. Fifty-seven patients with heparin-induced thrombocytopenia type II (HIT II) in whom r-hirudin was used during cardiovascular surgery with cardiopulmonary bypass (CPB). None. The r-hirudin concentration was monitored on-line, at the point of the patient's care using the ecarin clotting time and maintained in the range of 3 to 4 microg/mL. The r-hirudin elimination at the conclusion of CPB was augmented through modified zero-balanced ultrafiltration and forced diuresis. The duration of CPB was 63 to 246 minutes. The r-hirudin requirement per minute of CPB was 0.016 to 0.035 microg/kg/min, and the 24-hour blood drainage was 50 to 2,200 mL. Of the 57 patients, 54 fully recovered, including 9 patients who did not require any allogenic products. Four patients, all with impaired renal function, showed prolonged r-hirudin elimination and excessive bleeding and required surgical reexploration. Three patients died as a result of complications unrelated to the perioperative management. This study provides evidence that r-hirudin can be used safely and effectively for routine anticoagulation during CPB in patients diagnosed with HIT II. Almost 95% of the patients in whom it was used were discharged uneventfully. Patients with perioperative renal failure, however, showed increased bleeding.

Use of recombinant-hirudin in pulmonary thromboendarterectomy

A patient with chronic thromboembolic pulmonary hypertension and heparin-induced thrombocytopenia successfully underwent pulmonary thromboendarterectomy with circulatory arrest, using recombinant hirudin as an alternative anticoagulant to heparin. Techniques for administration as well as monitoring of this drug’s effects are discussed.

Determination of the dosage of recombinant hirudin to inhibit arterial thrombosis in baboons

Determination of the dosage of recombinant hirudin to inhibit arterial thrombosis in baboons

Delayed-type hypersensitivity skin reactions caused by subcutaneous unfractionated and low-molecular-weight heparins: Tolerance of a new recombinant hirudin

Eczema-like infiltrated plaques at subcutaneous heparin injection sites are well-documented side effects of these anticoagulants. However, surgical interventions may be problematic if heparin is urgently needed in these patients. The aims of this study were to perform extensive allergy skin testing in 24 patients, including a pregnant woman in whom subcutaneous infiltrated plaques developed after subcutaneous heparin injections, and to find safe therapeutic alternatives for this group of patients. Patch, intradermal, and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), and heparinoids. Since 1997, we have also been performing allergy studies in 8 patients with lepirudin, a new recombinant heparinoid; tolerance of lepirudin was investigated by means of subcutaneous and intravenous injections. The allergy investigations in the pregnant woman were limited to patch tests with heparins and intradermal and subcutaneous tests with pentosanpolysulfate, which are not contraindicated during pregnancy. In our study population 19 of 23 patients were sensitized to all the UFHs and LMWHs tested when intracutaneous and subcutaneous test results were read at up to 96 hours. LMWH was found to be a possible substitute in 4 patients. Five patients were also sensitized to the heparinoid pentosanpolysulfate. Sensitization to the heparinoid danaparoid was observed in 12 of the 13 patients who were tested with this substance. The administration of an intravenous bolus containing a therapeutic dose of lepirudin after negative subcutaneous provocation was tolerated without any side effects in all 8 patients. The pregnant woman was sensitized to LMWH but tolerated subcutaneous pentosanpolysulfate without any side effects. Extensive allergy skin testing should be performed to find safe alternatives. With few exceptions, all patients react to both UFHs and LMWHs, as well as to danaparoid. The subcutaneous provocation test is the most reliable diagnostic measure. Intravenous lepirudin, and in some cases subcutaneous pentosanpolysulfate, appears to be a safe alternative in patients with eczema-like infiltrated plaques at subcutaneous heparin-injection sites.

Delayed-type hypersensitivity skin reactions caused by subcutaneous unfractionated and low-molecular-weight heparins: Tolerance of a new recombinant hirudin

Background: Eczema-like infiltrated plaques at subcutaneous heparin injection sites are well-documented side effects of these anticoagulants. However, surgical interventions may be problematic if heparin is urgently needed in these patients. Objective: The aims of this study were to perform extensive allergy skin testing in 24 patients, including a pregnant woman in whom subcutaneous infiltrated plaques developed after subcutaneous heparin injections, and to find safe therapeutic alternatives for this group of patients. Methods: Patch, intradermal, and subcutaneous tests were performed with a panel of unfractionated heparins (UFHs), low-molecular-weight heparins (LMWHs), and heparinoids. Since 1997, we have also been performing allergy studies in 8 patients with lepirudin, a new recombinant heparinoid; tolerance of lepirudin was investigated by means of subcutaneous and intravenous injections. The allergy investigations in the pregnant woman were limited to patch tests with heparins and intradermal and subcutaneous tests with pentosanpolysulfate, which are not contraindicated during pregnancy. Results: In our study population 19 of 23 patients were sensitized to all the UFHs and LMWHs tested when intracutaneous and subcutaneous test results were read at up to 96 hours. LMWH was found to be a possible substitute in 4 patients. Five patients were also sensitized to the heparinoid pentosanpolysulfate. Sensitization to the heparinoid danaparoid was observed in 12 of the 13 patients who were tested with this substance. The administration of an intravenous bolus containing a therapeutic dose of lepirudin after negative subcutaneous provocation was tolerated without any side effects in all 8 patients. The pregnant woman was sensitized to LMWH but tolerated subcutaneous pentosanpolysulfate without any side effects. Conclusion: Extensive allergy skin testing should be performed to find safe alternatives. With few exceptions, all patients react to both UFHs and LMWHs, as well as to danaparoid. The subcutaneous provocation test is the most reliable diagnostic measure. Intravenous lepirudin, and in some cases subcutaneous pentosanpolysulfate, appears to be a safe alternative in patients with eczema-like infiltrated plaques at subcutaneous heparin-injection sites. (J Am Acad Dermatol 2000;42:612-9.)

Anticoagulative management of patients requiring left ventricular assist device implantation and suffering from heparin-induced thrombocytopenia type II

Background. Heparin-induced thrombocytopenia type II (HIT II) is a rare but life-threatening side effect of heparin therapy. We describe the perioperative anticoagulative management of patients tested positive for HIT II and requiring implantation of a left ventricular assist device (LVAD).Methods. We report on 3 patients with a different perioperative anticoagulative management (preoperative, intraoperative, and postoperative anticoagulation with danaparoid-sodium; preoperative anticoagulation with recombinant hirudin, anticoagulation with danaparoid-sodium intraoperatively and postoperatively; preoperative anticoagulation with recombinant hirudin, intraoperative anticoagulation with heparin, and postoperative anticoagulation with danaparoid-sodium) and discuss the difficulties of the treatment.Results. Anticoagulation with alternative drugs such as recombinant hirudin and danaparoid-sodium led to serious and life-threatening bleeding complications as well as to thromboembolic events in the first 2 patients. Therefore the third patient underwent LVAD implantation using heparin for intraoperative anticoagulation to avoid administration of high doses of recombinant hirudin or danaparoid-sodium. Despite very low anti-factor Xa activities, when using danaparoid-sodium postoperatively, the patient suffered from a bleeding complication on the 4th day after LVAD implantation requiring reexploration.Conclusions. In selected cases (negative heparin-induced platelet aggregation (HIPA) test at the time of LVAD implantation and continuation of postoperative anticoagulation with recombinant hirudin or danaparoid-sodium), heparin may be used for LVAD implantation in HIT II patients to reduce bleeding complications.

Role of clot-associated (-derived) thrombin in cell proliferation induced by fibrin clots in vitro.

Thrombin is a potent mitogenic agent. Clot-associated thrombin retains its amidolytic and pro-aggregant activity. We therefore studied the ability of fibrin clots to induce proliferation in CCL39 cells (Chinese hamster lung fibroblasts), in the absence and presence of the thrombin inhibitors PPACK, recombinant hirudin (rHV2 Lys47) and heparin:antithrombin III. Fibrin clots incubated for 48 h with CCL39 cells led to significant cell proliferation, which was dependent on the concentration of thrombin used to prepare the clots. Thus, clots prepared with 91 nmol l(-1) thrombin produced a similar proliferation (231+/-21%) to that obtained with 50 nmol l(-1) thrombin in solution (213+/-29%). Rabbit plasma clots led to a 499+/-41% increase in cell number under identical conditions. Fibrin clot-induced cell proliferation was inhibited by all three thrombin inhibitors with no difference in IC(50) values compared to those obtained against thrombin in solution, suggesting that cell proliferation be due to thrombin leaching from the clots. We found a time-dependent increase in thrombin release from the clots attaining a plateau at 24 h (approximately 61% of the total thrombin used in clot formation). Clots separated from the cells using porous cell culture chamber inserts led to similar proliferation to that of clots in contact with the cells. Thus fibrin-clot induced CCL39 proliferation is due to thrombin released from the clots.

Lepirudin blunts endotoxin-induced coagulation activation

During sepsis, lipopolysaccharide (LPS) triggers the development of disseminated intravascular coagulation (DIC) via the tissue factor-dependent pathway of coagulation resulting in massive thrombin generation and fibrin polymerization. Recently, animal studies demonstrated that hirudin reduced fibrin deposition in liver and kidney and decreased mortality in LPS-induced DIC. Accordingly, the effects of recombinant hirudin (lepirudin) was compared with those caused by placebo on LPS-induced coagulation in humans. Twenty-four healthy male subjects participated in this randomized, double-blind, placebo-controlled, parallel group study. Volunteers received 2 ng/kg LPS intravenously, followed by a bolus-primed continuous infusion of placebo or lepirudin (Refludan, bolus: 0.1 mg/kg, infusion: 0.1 mg/kg/h for 5 hours) to achieve a 2-fold prolongation of the activated partial thromboplastin time (aPTT). LPS infusion enhanced thrombin activity as evidenced by a 20-fold increase of thrombin-antithrombin complexes (TAT), a 6-fold increase of polymerized soluble fibrin, termed thrombus precursor protein (TpP), and a 4-fold increase in D-dimer. In the lepirudin group, TAT increased only 5-fold, TpP increased by only 50%, and D-dimer only slightly exceeded baseline values (P <.01 versus placebo). Concomitantly, lepirudin also blunted thrombin generation evidenced by an attenuated rise in prothrombin fragment levels (F(1 + 2), P <. 01 versus placebo) and blunted the expression of tissue factor on circulating monocytes. This experimental model proved the anticoagulatory potency of lepirudin in LPS-induced coagulation activation. Results from this trial provide a rationale for a randomized clinical trial on the efficacy of lepirudin in DIC. (Blood. 2000;95:1729-1734)

Cardiovascular Surgery Without Cardiopulmonary Bypass in Patients with Heparin-Induced Thrombocytopenia Type II Using Anticoagulation with Recombinant Hirudin

Cardiovascular Surgery Without Cardiopulmonary Bypass in Patients with Heparin-Induced Thrombocytopenia Type II Using Anticoagulation with Recombinant Hirudin

Rapid selection of multiple gene integrant for the production of recombinant hirudin inHansenula polymorpha

For the rapid selection of higher recombinant hirudin producing strain in a methylotrophic yeastHansenula polymorpha, a multiple gene integration and dose-dependent selection vector, based on a telomere-associated ARS and a bacterial aminoglycoside 3-phosphotransferase ( (aph) gene, was adopted. Two hirudin expression cassettes (HV1 and HV2) were constructed using theMOX promoter ofH. polymorpha and the mating factor α secretion signal ofS. cerevisiae. Multiple integrants of a transformang vector containing hirudin expression cassettes were easily selected by using an antibiotic, G418. Hirudin expression level and integrated plasmid copy number of the tested transformants increased with increasing the concentration of G418 used for selection. The expression level of HV1 was consistently higher than that of HV2 under the similar conditions, suggesting that the gene context might be quite important for the high-level gene expression inH. polymorpha. The highest hirudin producing strain selected in this study produced over 96 mg/L of biologically active hirudin in a 500-mL flask and 165 mg/L in a 5-L fermentor.

Statistical optimization of medium for the production of recombinant hirudin from Saccharomyces cerevisiae using response surface methodology

An efficient fermentation medium producing a colourless product with high yields has been developed for the production of recombinant hirudin from Saccharomyces cerevisiae. Response surface methodology was applied to optimize the medium constituents. A 2 5-1 fractional factorial central composite design has been chosen to explain the combined effect of the six medium constituents, viz. yeast extract, peptone, casamino acids, ammonium sulphate, potassium phosphate and galactose, and to design a minimum number of experiments. The optimized medium produced 65.3 mg/l of r-hirudin in shake flask culture, which is 35% higher than the unoptimized medium. The colour of the purified product was influenced by the colour intensity of culture supernatant, which in turn depended upon the concentration of complex substrates used in the medium. The concentration of yeast extract has been reduced to 16 g/l in the optimized medium than other reported media containing 40 g/l yeast extract. The colour intensity of culture supernatant obtained by the optimized medium was reduced by 60% from the reported media containing 40 g/l yeast extract.

Hirudin as anticoagulant for cardiopulmonary bypass: importance of preoperative renal function

Background. Recombinant hirudin is an alternative anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II. Although there is no neutralizing agent for recombinant hirudin, its fast renal elimination enables quick cessation of bleeding after cardiopulmonary bypass. The aim of the study was to compare anticoagulant effects of recombinant hirudin in regards to renal function in patients with heparin-induced thrombocytopenia type II.Methods. Twenty-one patients (mean age, 65 years, and range, 35 to 82 years) underwent different complex cardiovascular procedures using recombinant hirudin as the anticoagulant for cardiopulmonary bypass. Postoperative blood loss, transfusion requirements, and hemostatic variables were compared between patients with a creatinine level lower than 1.5 mg/dL (group 1, normal renal function; n = 17 patients) and those with a creatinine level greater than 1.5 mg/dL (group 2, impaired renal function; n = 4 patients).Results. The patients in group I showed no increased tendency toward postoperative bleeding. In contrast, all 4 patients in group 2 required reexploration for increased postoperative bleeding. They had higher activated partial thromboplastin times and transfusion requirements postoperatively.Conclusions. If recombinant hirudin is used as the anticoagulant for cardiopulmonary bypass in patients with heparin-induced thrombocytopenia type II and impaired renal function, the risk of postoperative bleeding is increased.

Management of patients with heparin-induced thrombocytopenia: focus on recombinant hirudin.

Management of patients with heparin-induced thrombocytopenia : focus on recombinant hirudin.

Hirudin-based anticoagulant strategies for patients with suspected heparin-induced thrombocytopenia undergoing percutaneous coronary interventions and bypass grafting.

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug reaction that is associated with thrombotic events of the venous and arterial circulatory systems stemming from an intense and well-characterized prothrombotic triad of platelet activation, coagulation cascade stimulation and vascular endothelial cell injury. Although heparin (or other sulfated mucopolysaccharide compound) cessation represents a vital first step in management, patients remain susceptible to life-threatening thrombosis for up to several weeks, providing a strong rationale for a 'proactive approach' to care that includes prompt initiation of an alternative anticoagulant strategy throughout the high-risk period. The importance of alternative options for anticoagulation is most evident in clinical situations wherein treatment is a recognized standard of care and prerequisite for an optimal outcome. The following review highlights the use of recombinant hirudin (lepirudin) among patients with suspected HIT requiring precutaneous coronary interventions (PCI) and coronary arterial bypass grafting.

Heparin vs recombinant hirudin for anticoagulation in continuous renal replacement therapy

Heparin vs recombinant hirudin for anticoagulation in continuous renal replacement therapy