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1.
Int Angiol ; 31(4): 330-9, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22801398

ABSTRACT

AIM: A network meta-analysis of the three new oral anticoagulants was performed from the three trials comparing dabigatran, rivaroxaban and apixaban with warfarin in patients with atrial fibrillation. METHODS: Data were extracted of the RE-LY study of dabigatran 110 mg bid and dabigatran 150 mg bid, the ROCKET AF trial of rivaroxaban and the ARISTOTLE trial of apixaban for the composite outcome of ischemic stroke and systemic embolism, for major bleeding, intracerebral bleeding, mortality and myocardial infarction. RESULTS: Dabigatran (150 mg bid) showed superior efficacy in preventing ischemic stroke plus systemic embolism to dabigatran (110 mg bid, P=0.0364) and rivaroxaban (P=0.0388). Apixaban had equivalent efficacy with rivaroxaban and dabigatran (either dose). Apixaban was safer (less major bleeding) than dabigatran (150 mg bid, P=0.036) or rivaroxaban (P=0.0002). Intracerebral hemorrhage occurred with equal frequency for all agents except for rivaroxaban (higher risk than dabigatran 110 mg bid, P=0.0070). Myocardial infarction occurred less frequently with rivaroxaban and apixaban compared to either dose of dabigatran (all P<0.05). CONCLUSION: All-cause mortality was not different for any agent or regimen. In the absence of head-to-head comparisons, this network meta-analysis suggests that apixaban and dabigatran 110 mg bid may offer the best benefit-risk balance for stroke prevention in non-valvular atrial fibrillation. Dabigatran 150 mg bid may be preferred for patients with a high risk for embolism.


Subject(s)
Anticoagulants/therapeutic use , Atrial Fibrillation/drug therapy , Benzimidazoles/therapeutic use , Embolism/prevention & control , Morpholines/therapeutic use , Pyrazoles/therapeutic use , Pyridones/therapeutic use , Stroke/drug therapy , Thiophenes/therapeutic use , beta-Alanine/analogs & derivatives , Administration, Oral , Aged , Anticoagulants/administration & dosage , Anticoagulants/adverse effects , Atrial Fibrillation/complications , Atrial Fibrillation/mortality , Benzimidazoles/administration & dosage , Benzimidazoles/adverse effects , Cerebral Hemorrhage/chemically induced , Chi-Square Distribution , Dabigatran , Embolism/etiology , Embolism/mortality , Female , Humans , Male , Middle Aged , Morpholines/administration & dosage , Morpholines/adverse effects , Myocardial Infarction/etiology , Odds Ratio , Pyrazoles/administration & dosage , Pyrazoles/adverse effects , Pyridones/administration & dosage , Pyridones/adverse effects , Risk Assessment , Risk Factors , Rivaroxaban , Stroke/etiology , Stroke/mortality , Thiophenes/administration & dosage , Thiophenes/adverse effects , Treatment Outcome , beta-Alanine/administration & dosage , beta-Alanine/adverse effects , beta-Alanine/therapeutic use
2.
J Thromb Haemost ; 10(6): 985-91, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22487025

ABSTRACT

BACKGROUND: Current treatment of acute peripheral artery or bypass graft occlusion utilizes catheter-directed thrombolysis of a plasminogen activator (PA). Plasmin is a direct-acting thrombolytic with a striking safety advantage over PA in preclinical models. OBJECTIVES: To report the first use of purified plasmin for acute lower extremity arterial or bypass graft thrombosis in a phase I dose-escalation study of a catheter-delivered agent. METHODS: Eighty-three patients with non-embolic occlusion of infrainguinal native arteries or bypass grafts were enrolled (safety population) into seven sequential dose cohorts to receive 25-175 mg of plasmin by intrathrombus infusion over 5 h. Arteriograms were performed at baseline, 2 h, and 5 h, and subjects were monitored for 30 days for clinical outcomes and laboratory parameters of systemic fibrinolysis. RESULTS: Major bleeding occurred in four patients (4.8%), and minor bleeding alone in 13 (15.7%), with no trend towards more bleeding at higher dosages of plasmin. There was a trend towards lower plasma concentrations of fibrinogen, α(2) -antiplasmin and α(2) -macroglobulin with increasing doses of plasmin, but the nadir fibrinogen concentration was > 350 mg dL(-1) at the highest plasmin dose. Individual nadir values were above 200 mg dL(-1) in 82 of 83 subjects, and were not different in patients with or without bleeding. Thrombolysis (≥ 50%) occurred in 79% of subjects receiving 125-175 mg of plasmin, as compared with 50% who received 25-100 mg. CONCLUSIONS: Catheter-delivered plasmin can be safely administered to patients with acute lower extremity arterial occlusion at dosages of 25-175 mg.


Subject(s)
Arterial Occlusive Diseases/drug therapy , Catheterization, Peripheral , Fibrinolysin/administration & dosage , Fibrinolytic Agents/administration & dosage , Graft Occlusion, Vascular/drug therapy , Lower Extremity/blood supply , Thrombolytic Therapy/methods , Acute Disease , Adolescent , Adult , Aged , Aged, 80 and over , Arterial Occlusive Diseases/blood , Arterial Occlusive Diseases/diagnostic imaging , Biomarkers/blood , Brazil , Catheterization, Peripheral/adverse effects , Dose-Response Relationship, Drug , Europe , Female , Fibrinogen/metabolism , Fibrinolysin/adverse effects , Fibrinolytic Agents/adverse effects , Graft Occlusion, Vascular/blood , Graft Occlusion, Vascular/diagnostic imaging , Hemorrhage/chemically induced , Humans , Infusions, Intra-Arterial , Male , Middle Aged , Radiography , South Africa , Thrombolytic Therapy/adverse effects , Time Factors , Treatment Outcome , United States , Young Adult , alpha-2-Antiplasmin/metabolism , alpha-Macroglobulins/metabolism
3.
J Thromb Haemost ; 9 Suppl 1: 364-73, 2011 Jul.
Article in English | MEDLINE | ID: mdl-21781273

ABSTRACT

Two issues have held the focus of thrombolysis research for over 50 years, namely, choosing between a plasminogen activator (PA) or plasmin as the best therapeutic agent and choosing between systemic or local administration. The original plasmin product of the 1950s was both ineffective and contaminated with PA, and catheter technology was not yet developed for routine clinical use. For decades, clinical practice has focused on PA and systemic administration, but today, PAs are often administered by catheter into thrombosed vessels, notably for peripheral arterial and graft occlusion and deep vein thrombosis, and increasingly for acute ischaemic stroke. Despite using catheter-delivered therapy, bleeding complications still occur, most severely expressed as symptomatic intracranial haemorrhage. New experimental data indicate that we should now reconsider plasmin as a viable, even preferable, thrombolytic agent. Plasmin requires catheter delivery to achieve thrombolysis, but this technical issue has been solved with modern technology and widespread presence of interventional suites. After local administration, plasmin will lyse thrombi; thereafter, any plasmin in the circulation will be rapidly neutralised. Pre-clinical studies confirm that plasmin has marked haemostatic safety advantage over t-PA. After more than 50 years, the field has come full circle, and plasmin as the thrombolytic agent and catheter use for local delivery of agent may represent a step forward in thrombolytic therapy.


Subject(s)
Biomedical Research/history , Fibrinolysin/therapeutic use , Fibrinolysis , Thrombosis/drug therapy , Biomedical Research/trends , Clinical Trials as Topic , Fibrinolysin/adverse effects , History, 20th Century , History, 21st Century
4.
J Thromb Haemost ; 8(3): 504-12, 2010 Mar.
Article in English | MEDLINE | ID: mdl-20050998

ABSTRACT

BACKGROUND: Heparin-induced thrombocytopenia is an antibody-mediated disorder exhibiting variable frequency in different clinical settings. Antibodies recognize PF4/heparin complexes formed at optimal stoichiometric molar ratios. OBJECTIVE: To identify clinical factors influencing risk of anti-PF4/heparin immunization. PATIENTS/METHODS: We performed observational studies and exploratory analyses of the frequency of anti-PF4/heparin antibody formation in 6324 patients who received enoxaparin or fondaparinux in four randomized controlled trials of postorthopedic surgery thromboprophylaxis. Variables included surgery type (knee vs. hip), timing of first anticoagulant dose (pre- vs. postsurgery), circumstances of surgery (elective vs. hip fracture), anticoagulant (enoxaparin vs. fondaparinux) and body-mass index (BMI). We applied a stoichiometry-based model that predicts immunization risk based on expected differences in PF4/anticoagulant ratios in different settings, and specifically used this model to predict the effect of increasing BMI quartiles upon relative risk (RR) of immunization for fondaparinux vs. enoxaparin. RESULTS: Anti-PF4/heparin immunization was more frequent after knee vs. hip surgery (particularly for enoxaparin), and when enoxaparin was given post- rather than pre-elective surgery; however, the opposite occurred with hip fracture surgery, that is, antibody formation was more frequent when enoxaparin or fondaparinux was given presurgery. The RR of immunization for fondaparinux vs. enoxaparin decreased significantly for increasing BMI quartiles, an effect predominantly because of increasing immunization with enoxaparin at increasing BMI quartiles. CONCLUSIONS: Several non-drug factors--including type and circumstances of surgery, timing of first anticoagulant dose and BMI--influence risk of anti-PF4/heparin antibody formation, consistent with a stoichiometry-based immunization model of PF4 and anticoagulant ratios occurring during the early peri-operative period.


Subject(s)
Antibodies/blood , Anticoagulants/adverse effects , Enoxaparin/adverse effects , Orthopedic Procedures/adverse effects , Platelet Factor 4/immunology , Polysaccharides/adverse effects , Thrombocytopenia/chemically induced , Thrombosis/prevention & control , Anticoagulants/administration & dosage , Anticoagulants/immunology , Body Mass Index , Drug Administration Schedule , Enoxaparin/administration & dosage , Enoxaparin/immunology , Evidence-Based Medicine , Fondaparinux , Humans , Models, Statistical , Polysaccharides/administration & dosage , Polysaccharides/immunology , Randomized Controlled Trials as Topic , Risk Assessment , Risk Factors , Thrombocytopenia/immunology , Thrombosis/etiology , Thrombosis/immunology
5.
J Thromb Haemost ; 8(3): 433-44, 2010 Mar.
Article in English | MEDLINE | ID: mdl-19943877

ABSTRACT

Direct fibrinolytics are proteolytic enzymes that degrade fibrin without requiring an intermediate step of plasminogen activation. This review summarizes the current information available for five such agents, namely, plasmin (the prototypical form), three derivatives of plasmin (mini-plasmin, micro-plasmin, and delta-plasmin), and alfimeprase, a recombinant variant of a snake venom alpha-fibrinogenase, fibrolase. Biochemical attributes of molecular size, fibrin binding and inhibitor neutralization are compared. Preclinical investigations that assess the potential for thrombolytic efficacy in vitro and in animal models of vascular occlusion and for hemostatic safety in animal models of bleeding are detailed. Clinical potential has been assessed in patients with peripheral arterial and graft occlusion, acute ischemic stroke, and access catheter and hemodialysis shunt occlusions. The direct fibrinolytic agents have impressive biochemical and preclinical foundations for ultimate clinical application. However, clinical trial results for micro-plasmin and alfimeprase have not measured up to their anticipated benefit. Plasmin has thus far shown encouraging hemostatic safety, but efficacy data await completion of clinical trials. Whether direct fibrinolytics will provide clinical superiority in major thrombotic disorders over currently utilized indirect fibrinolytics such as tissue plasminogen activator remains to be determined.


Subject(s)
Cardiovascular Diseases/drug therapy , Fibrin/metabolism , Fibrinolysis/drug effects , Fibrinolytic Agents/therapeutic use , Thrombolytic Therapy , Animals , Cardiovascular Diseases/blood , Disease Models, Animal , Fibrinolysin/therapeutic use , Fibrinolytic Agents/adverse effects , Fibrinolytic Agents/pharmacology , Hemorrhage/chemically induced , Humans , Metalloendopeptidases/therapeutic use , Peptide Fragments/therapeutic use , Thrombolytic Therapy/adverse effects
6.
J Thromb Haemost ; 6(6): 944-50, 2008 Jun.
Article in English | MEDLINE | ID: mdl-18384651

ABSTRACT

BACKGROUND: Hemodialysis (HD) grafts often fail because of stenosis at the venous anastomosis and thrombotic occlusion. Percutaneous management relies on thrombolysis with plasminogen activators, mechanical removal of thrombus, and angioplasty of the stenotic lesion. OBJECTIVES: This report describes a phase I trial using Plasmin (Human) TAL 05-00018, a direct-acting fibrinolytic agent, to evaluate safety and, secondarily, to establish effective thrombolytic dosing. PATIENTS/METHODS: Six cohorts of five patients with acute HD graft occlusion documented by angiography were treated with escalating dosages of plasmin (1, 2, 4, 8, 12, and 24 mg) infused over 30 min via criss-crossed pulse-spray catheters within the graft. The primary efficacy endpoint was > or =50% thrombolysis, as determined by comparison of pre-plasmin and 30-min post-plasmin fistulograms. RESULTS: Of 31 subjects who received study drug (safety population), one withdrew and 30 completed the trial (evaluable for efficacy). There was no significant change in plasma alpha-2 antiplasmin or fibrinogen concentration, major bleeding did not occur, and there were no deaths. Serious adverse events in four patients were not related to the study drug. There was a dose-response relationship for the primary efficacy endpoint, all five subjects receiving 24 mg achieving >75% lysis. CONCLUSIONS: This first phase I study of Plasmin (Human) TAL 05-00018, infused into thrombosed HD grafts, documents safety at dosages of 1-24 mg and an effective thrombolytic dosage of 24 mg. The results establish a foundation for further clinical study of catheter-based plasmin administration in thrombotic disorders.


Subject(s)
Fibrinolysin/administration & dosage , Fibrinolysin/pharmacology , Renal Dialysis/methods , Thrombolytic Therapy/instrumentation , Adult , Aged , Aged, 80 and over , Blood Coagulation , Cohort Studies , Dose-Response Relationship, Drug , Female , Fibrinolysin/chemistry , Fibrinolysin/metabolism , Fibrinolytic Agents/pharmacology , Humans , Ischemia/pathology , Male , Middle Aged , Thrombolytic Therapy/methods , Thrombosis/pathology
7.
J Thromb Haemost ; 5(2): 274-81, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17137472

ABSTRACT

BACKGROUND: Bleeding symptoms are so commonly reported that it is not known whether they associate causally or coincidentally with mild but measurable primary hemostatic defects. OBJECTIVES/PATIENTS/METHODS: In order to evaluate if the mild primary hemostatic defects are truly causative of increased bleeding symptoms, we surveyed a population of healthy teenagers for bleeding symptoms. Using a case-control approach, we then estimated the risk of excessive bleeding associated with low von Willebrand factor (defined as VWF below the 5th percentile of a normal reference population), and with mild platelet dysfunction [PD, defined as concurrent reduced platelet aggregation responses to two agonists (adenosine diphosphate and epinephrine)]. RESULTS: Excessive bleeding was present in 63 out of 809 teenagers (7.8%). Among the 49 cases who were tested for VWF, low values by three measures were more commonly present than in 166 controls, specifically, ristocetin cofactor (RCo) activity [20.4% vs. 5.4%, odds ratio (OR) 4.5], collagen binding (14.3% vs. 4.2%, OR 3.8), and antigen level (20.4% vs. 6.0%, OR 4.0). The low RCo values ranged from 35 to 45 U dL(-1) except for a single case with 26 U dL(-1). Of the 47 teenagers with excessive bleeding who underwent platelet aggregation studies, reduced responses were more common than in controls (12.8% vs. 4.4%, OR 3.2). Twenty-nine per cent of cases with excessive bleeding had either low RCo or PD. CONCLUSION: Almost one in three teenagers who report excessive bleeding is likely to have a measurable hemostatic disturbance manifested either by marginally low VWF (by three measures) or by mild PD.


Subject(s)
Blood Platelet Disorders/complications , Hemorrhage/etiology , von Willebrand Factor/analysis , Adolescent , Case-Control Studies , Female , Hemorrhage/epidemiology , Humans , Male , Platelet Aggregation , Platelet Function Tests , Risk , Surveys and Questionnaires
8.
J Thromb Haemost ; 4(7): 1575-9, 2006 Jul.
Article in English | MEDLINE | ID: mdl-16839356

ABSTRACT

BACKGROUND: Increasing circulating magnesium concentrations to 2-fold over normal baseline may afford a neuroprotective effect in patients with acute cerebral ischemia. OBJECTIVES: As patients receiving magnesium sulfate (MgSO(4)) in human clinical trials may also be candidates for subsequent thrombolytic therapy with tissue plasminogen activator (t-PA), preclinical assessment of possible inhibition or potentiation of fibrinolytic activity by MgSO(4) has important clinical relevance. METHODS: We utilized an in vitro system, in which D-dimer release served as a reflection of t-PA-induced clot lysis, to measure the effect of magnesium at the target concentration being tested in human stroke clinical trials, and at 2- and 3-fold higher levels. Clots from normal volunteers were exposed to t-PA at concentrations that correspond to therapeutic or endogenous plasma t-PA levels. RESULTS: MgSO(4) had no effect on t-PA-induced clot lysis at up to 3-fold target magnesium concentration (6x normal serum concentration). CONCLUSIONS: MgSO(4) concentrations well above the targeted level in therapeutic stroke trials does not affect t-PA-induced fibrinolytic activity, and therefore is a suitable agent for trials of combined neuroprotective and thrombolytic therapy in patients with acute ischemic stroke.


Subject(s)
Fibrinolysis/drug effects , Magnesium Sulfate/pharmacology , Thrombolytic Therapy/methods , Tissue Plasminogen Activator/pharmacology , Dose-Response Relationship, Drug , Female , Fibrin Fibrinogen Degradation Products/analysis , Humans , In Vitro Techniques , Magnesium Sulfate/administration & dosage , Magnesium Sulfate/blood , Male , Neuroprotective Agents/pharmacology , Stroke/drug therapy , Tissue Plasminogen Activator/therapeutic use
10.
J Thromb Haemost ; 1(12): 2621-5, 2003 Dec.
Article in English | MEDLINE | ID: mdl-14675099

ABSTRACT

Plasmin is a direct thrombolytic which has been shown to have a strikingly favorable benefit to risk profile in comparison with plasminogen activators, notably tissue plasminogen activator (t-PA). As heparin is known to increase the risk of hemorrhage when co-administered with a plasminogen activator, we asked whether adjunct antithrombotic agents such as aspirin and heparin would affect the safety of plasmin. Three groups of rabbits were administered plasmin at a dose (4 mg kg-1) designed to induce significant decreases in antiplasmin, fibrinogen and factor (F)VIII, to about 25, 40 and 40%, respectively, of baseline values, but not cause prolongation of the ear puncture bleeding time. In a blinded and randomized trial, the results show that an intravenous aspirin bolus plus heparin administered as a bolus followed by a maintenance continuous infusion did not significantly prolong the bleeding time during plasmin infusion. These data indicate that in the rabbit, concomitant use of aspirin plus heparin does not affect the safety of a therapeutic dose of plasmin.


Subject(s)
Fibrinolytic Agents/administration & dosage , Fibrinolytic Agents/adverse effects , Hemorrhage/chemically induced , Animals , Aspirin/administration & dosage , Aspirin/adverse effects , Bleeding Time , Drug Interactions , Drug Therapy, Combination , Fibrinolysin/administration & dosage , Fibrinolysin/adverse effects , Heparin/administration & dosage , Heparin/adverse effects , Models, Animal , Rabbits , Thrombolytic Therapy/adverse effects
11.
J Thromb Haemost ; 1(9): 1914-9, 2003 Sep.
Article in English | MEDLINE | ID: mdl-12941031

ABSTRACT

BACKGROUND: Unfractionated heparin (UFH) is safe and effective for thromboprophylaxis, but its use is limited to parenteral administration. A novel drug delivery agent (SNAC) has been developed to accomplish the oral delivery of heparin. OBJECTIVE: This report describes the foundation for dose selection and use of oral heparin/SNAC in patients undergoing elective total hip arthroplasty (THA). PATIENTS AND METHODS: To develop a treatment regimen for clinical study, a multiple dose Phase I pharmacokinetic (PK) study in healthy volunteers compared oral heparin/SNAC (90 000 U heparin) with subcutaneous UFH (5000 U). On this basis, we carried out a double-blind, randomized, multicenter study comparing subcutaneous UFH (5000 U) with oral heparin/SNAC at either 60 000 or 90 000 U heparin in 123 patients undergoing elective THA. Patients received, postoperatively, one of the three treatments every 8 h for a total of 12 doses and were followed for 35 days post surgery. RESULTS: In the Phase I study, anti-factor Xa activity peaked at 45-60 min following oral heparin/SNAC, returning to baseline at 4 h. RESULTS of the randomized trial in THA patients showed that venous thromboembolic events (n = 6), major bleeding events (n = 5) and need for transfusion (n = 23) were distributed evenly among the three treatment groups, UFH and both doses of oral heparin/SNAC. CONCLUSION: This is the first demonstration that oral heparin/SNAC can be safely delivered to the postoperative THA patient, and provides the basis for a larger clinical trial to assess the prophylactic efficacy of heparin/SNAC.


Subject(s)
Arthroplasty, Replacement, Hip/adverse effects , Drug Carriers , Heparin/administration & dosage , Thrombosis/prevention & control , Adolescent , Adult , Aged , Blood Transfusion , Caprylates , Factor Xa Inhibitors , Female , Hemorrhage/chemically induced , Heparin/adverse effects , Heparin/pharmacokinetics , Humans , Male , Middle Aged , Partial Thromboplastin Time , Pharmacokinetics , Postoperative Care , Thrombosis/drug therapy
12.
Ann Hematol ; 82(11): 702-4, 2003 Nov.
Article in English | MEDLINE | ID: mdl-12923661

ABSTRACT

We report a patient with hemoglobin sickle cell-hemoglobin C disease who developed the clinical syndrome of thrombotic thrombocytopenic purpura (TTP) during admission for typical acute pain crisis. The potential for multiorgan involvement secondary to vaso-occlusive crisis complicated the diagnosis and overlapped with the patient's clinical presentation of chronic bone pain and hemolytic anemia. Clinical improvement and normalization of laboratory parameters followed rapidly in response to plasma exchange therapy.


Subject(s)
Hemoglobin SC Disease/complications , Purpura, Thrombotic Thrombocytopenic/complications , Adult , Humans , Male , Pain/etiology , Pain Management , Plasma Exchange , Purpura, Thrombotic Thrombocytopenic/blood , Purpura, Thrombotic Thrombocytopenic/therapy
13.
J Thromb Haemost ; 1(4): 760-5, 2003 Apr.
Article in English | MEDLINE | ID: mdl-12871413

ABSTRACT

While protamine sulfate reverses the anticoagulant effect of standard heparin, there currently is no effective antidote for low molecular weight heparin (LMWH)-induced bleeding. Recently, recombinant activated factor VII (rFVIIa) was approved by the FDA for use in hemophilia patients with factor (F)VIII or FIX inhibitors. However, this new pro-hemostatic agent has potential utility in other clinical scenarios. In this study, we utilized a well-characterized rabbit ear puncture model to test the efficacy of rFVIIa to reverse LMWH-induced prolonged bleeding. Animals were first treated with bolus intravenous LMWH (1800 anti-FXa U kg(-1)) which increased the primary bleeding time approximately fourfold and raised the plasma anti-FXa activity immediately and continuously throughout the 90-min experiment. In a randomized and blinded fashion, animals then received either rFVIIa (400 microg kg(-1)) or placebo by bolus intravenous injection, following which the ear puncture bleeding times were measured, along with blood levels of heparin (anti-FXa activity) and FVII. FVII activity increased 5.3-fold over baseline in treated animals, decreasing by only 24% over the full observation period. The rFVIIa-treated animals showed a slight decrease in bleeding time immediately after injection, but there was no statistically significant difference in bleeding after rFVIIa or placebo administration. In this study using a rabbit ear bleeding model, rFVIIa was not an effective antidote to LMWH-induced bleeding. However, the bolus injection of LMWH produced a very high blood anti-FXa level, which may have precluded rFVIIa effectiveness.


Subject(s)
Factor VII/therapeutic use , Hemorrhage/drug therapy , Heparin, Low-Molecular-Weight/adverse effects , Recombinant Proteins/therapeutic use , Animals , Antidotes , Bleeding Time , Drug Evaluation , Factor VII/pharmacology , Factor VIIa , Hemorrhage/chemically induced , Hemostasis/drug effects , Kinetics , Male , Rabbits , Recombinant Proteins/pharmacology , Tinzaparin
15.
Curr Opin Pulm Med ; 7(5): 344-8, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11584187

ABSTRACT

The heparins, (unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH)) given by subcutaneous or intravenous injection have been used extensively in the prevention and treatment of both venous and arterial thromboembolic disorders. The increasing use of the heparins, LMWHs in particular, in the out of hospital setting has stimulated interest in the development of orally absorbable antithrombotic agents that require little or no monitoring, and this includes the heparins. UFH or LMWH delivered orally has been shown to have an antithrombotic effect in animal thrombosis models although there is little change in plasma coagulation tests. The addition of a simple organic chemical N -(8-(2-hydroxybenzoyl)amino)caprylate (SNAC) to UFH markedly enhances its absorption. A phase II study in patients undergoing total hip replacement indicated that SNAC heparin in two different doses was as effective and safe as UFH given subcutaneously. A phase III clinical trial comparing two doses of SNAC heparin given orally with LMWH by subcutaneous injection for the prevention of venous thromboembolism in patients undergoing total hip replacement is currently underway.


Subject(s)
Anticoagulants/therapeutic use , Heparin, Low-Molecular-Weight/therapeutic use , Heparin/therapeutic use , Thromboembolism/prevention & control , Administration, Oral , Animals , Anticoagulants/administration & dosage , Arthroplasty, Replacement, Hip/adverse effects , Caprylates/pharmacology , Caprylates/therapeutic use , Disease Models, Animal , Drug Delivery Systems , Heparin/administration & dosage , Heparin, Low-Molecular-Weight/administration & dosage , Humans , Intestinal Absorption , Meta-Analysis as Topic , Thromboembolism/etiology
16.
Thromb Haemost ; 86(3): 739-45, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11583303

ABSTRACT

The direct fibrinolytic enzyme, plasmin, was compared with tissue plasminogen activator (TPA) in rabbit models of local thrombolysis and fibrinolytic hemorrhage. Plasmin was produced by solid-phase urokinase activation of plasminogen and purified on benzamidine Sepharose. Applied as an intra-arterial infusion into the thrombosed abdominal aorta under conditions of unimpeded blood flow, plasmin (4 mg/kg) and TPA (2 mg/kg) achieved equivalent clot dissolution and flow restoration. Using the model of restricted blood flow into the thrombosed aorta, which limits local plasminogen supply, plasmin was superior to TPA in clot lysis and vascular reperfusion. Using similar dosages of plasmin (2 or 4 mg/kg) and TPA (1 or 2 mg/kg) in the earpuncture rebleed model. TPA induced rebleeding in a dose-dependent manner from prior puncture sites in 9 of 10 animals, while none of the 10 animals exposed to plasmin rebled from these sites. These results suggest that plasmin is an effective, unique thrombolytic agent, distinguished from the plasminogen activators in current usage by its striking safety profile.


Subject(s)
Aortic Diseases/drug therapy , Fibrinolysin/therapeutic use , Fibrinolysis/drug effects , Fibrinolytic Agents/therapeutic use , Hemorrhage/prevention & control , Thrombolytic Therapy , Thrombosis/drug therapy , Tissue Plasminogen Activator/therapeutic use , Animals , Aorta, Abdominal , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical , Ear , Fibrinolysin/pharmacology , Fibrinolytic Agents/pharmacology , Hemorrhage/chemically induced , Infusions, Intra-Arterial , Rabbits , Recurrence , Safety , Thrombolytic Therapy/adverse effects , Tissue Plasminogen Activator/pharmacology
17.
Thromb Haemost ; 86(3): 791-9, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11583309

ABSTRACT

Diabetes is an established risk factor for reinfarction and cardiac death in postinfarction patients. Since the underlying mechanism of diabetes-related risk is not fully understood we aimed to evaluate the association between lipids, thrombogenic factors and diabetes in postinfarction patients. The study population consisted of 1,045 postinfarction patients (846 non-diabetic, 125 non-insulin- and 74 insulin-requiring diabetics) with the following blood tests performed 2 months after an index myocardial infarction: lipoprotein (a), apolipoprotein-B, apolipoprotein-A, cholesterol, HDL cholesterol, triglycerides, insulin, von Willebrand factor (vWF), fibrinogen, factor VII, D-dimer, and plasminogen activator inhibitor (PAI-1). After adjustment for relevant clinical covariates, non-insulin-requiring diabetes was significantly (p < 0.05) associated with elevated levels of (odd ratios per 1 log unit increase in parenthesis) vWF (1.74) and PAI-1 (1.42) whereas insulin requiring diabetes was associated with even more elevated levels of vWF (4.68), but not with increased levels of PAI-1. No significant differences in lipid levels were observed among three groups. In conclusion, increased level of von Willebrand factor is significantly and independently associated with diabetes in postinfarction patients, suggesting that endothelial damage is the primary mechanisms contributing to an increased occurrence of vascular and cardiac events in diabetic postinfarction patients.


Subject(s)
Diabetes Mellitus/blood , Myocardial Infarction/blood , von Willebrand Factor/analysis , Adult , Aged , Blood Glucose/analysis , Blood Proteins/analysis , Convalescence , Diabetes Mellitus, Type 1/blood , Diabetes Mellitus, Type 2/blood , Endothelium, Vascular/pathology , Female , Humans , Insulin/blood , Lipids/blood , Lipoproteins/blood , Male , Middle Aged , Multivariate Analysis , New York/epidemiology , Odds Ratio , Plasminogen Activator Inhibitor 1/analysis , Risk Factors
18.
Arch Intern Med ; 161(16): 1952-60, 2001 Sep 10.
Article in English | MEDLINE | ID: mdl-11525697

ABSTRACT

BACKGROUND: Perioperative and postoperative venous thrombosis are common in patients undergoing elective hip surgery. Prophylactic regimens include subcutaneous low-molecular-weight heparin 12 hours or more before or after surgery and oral anticoagulants. Recent clinical trials suggest that low-molecular-weight heparin initiated in closer proximity to surgery is more effective than the present clinical practice. We performed a systematic review of the literature to assess the efficacy and safety of low-molecular-weight heparin administered at different times in relation to surgery vs oral anticoagulant prophylaxis. METHODS: Reviewers (A.F.M. and S.M.M.) identified studies by searching MEDLINE, reviewing references from retrieved articles, scanning abstracts from conference proceedings, and contacting investigators and pharmaceutical companies. Randomized trials comparing low-molecular-weight heparin administered at different times relative to surgery with oral anticoagulants in patients undergoing elective hip arthroplasty, evaluated using contrast phlebography, were selected. Two reviewers (A.F.M. and S.M.M.) extracted data independently. RESULTS: The literature review identified 4 randomized trials meeting predefined inclusion criteria. The results indicate that low-molecular-weight heparin initiated in close proximity to surgery resulted in absolute risk reductions of 11% to 13% for deep vein thrombosis, corresponding to relative risk reductions of 43% to 55% compared with oral anticoagulants. Low-molecular-weight heparin initiated 12 hours before surgery or 12 to 24 hours postoperatively was not more effective than oral anticoagulants. Low-molecular-weight heparin initiated postoperatively in close proximity to surgery at half the usual dose was not associated with a clinically or statistically significant increase in major bleeding rates (P =.16). CONCLUSIONS: The timing of initiating low-molecular-weight heparin significantly influences antithrombotic effectiveness. The practice of delayed initiation of low-molecular-weight heparin prophylaxis results in suboptimal antithrombotic effectiveness without a substantive safety advantage.


Subject(s)
Anticoagulants/administration & dosage , Arthroplasty, Replacement, Hip/adverse effects , Heparin, Low-Molecular-Weight/administration & dosage , Venous Thrombosis/prevention & control , Administration, Oral , Drug Administration Schedule , Elective Surgical Procedures/adverse effects , Humans , Injections, Subcutaneous , Odds Ratio , Randomized Controlled Trials as Topic , Research Design , Risk , Venous Thrombosis/etiology
19.
Blood Rev ; 15(1): 31-48, 2001 Mar.
Article in English | MEDLINE | ID: mdl-11333137

ABSTRACT

As the biochemical mechanisms of hypercoagulable states are revealed, the syndromes of venous thromboembolism have been increasingly associated with specific aberrations. Most of these changes involve an increase in procoagulant potential, for example, by activation of the coagulation cascade, or by a defect or decrease in natural inhibitors of clotting. Similar abnormalities of the fibrinolytic pathways may contribute, as can loss of inhibitory mechanisms of endothelial cells, as well as changes in vascular anatomy and rheologic patterns of blood flow. All of these factors can directly influence thrombus formation and/or the physiologic response to the thrombus.(1)


Subject(s)
Thrombophilia/etiology , Humans , Neoplasms/blood , Neoplasms/complications , Syndrome , Thrombophilia/blood , Thrombophilia/chemically induced , Thrombosis/blood , Thrombosis/chemically induced , Thrombosis/etiology
20.
Am J Cardiol ; 86(8): 813-8, 2000 Oct 15.
Article in English | MEDLINE | ID: mdl-11024393

ABSTRACT

Cigarette smoking is linked to increased cardiac morbidity and mortality, and has been shown to affect both lipid profiles and thrombotic factors in healthy subjects. However, the influence of smoking on the atherothrombotic environment has not been studied in a large population of patients after acute myocardial infarction (AMI). Blood samples and medical history, including smoking status, were obtained from 1,045 patients at a 2-month visit after AMI. Smokers were asked to refrain 24 hours before the visit, but not all complied. Measurements included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, apolipoprotein-B, apolipoprotein-A, triglycerides, factor VII, factor VIIa, von Willebrand factor, D-dimer, and plasminogen activator inhibitor. There were 247 current, 443 past, and 349 nonsmokers. After adjustment for clinical variables, current smokers had higher levels of total cholesterol and apolipoprotein-B than past and nonsmokers (p <0.01). High-density lipoprotein cholesterol and apolipoprotein-A levels were similar between groups. Fibrinogen was elevated in current (p = 0.001) and past (p = 0.029) smokers, compared with nonsmokers. Smokers who smoked within 24 hours of blood sampling had higher apolipoprotein-B (p = 0.005), total cholesterol (p = 0.001), and fibrinogen (p = 0.015) levels than those who refrained from smoking. In conclusion, postinfarction patients, who historically have higher levels of atherogenic lipids than healthy subjects, have increased levels of these lipids attributed to active smoking. After smoking cessation, lipid profiles approach nonsmoker levels, but fibrinogen remains elevated. Smoking within 24 hours of blood sampling was associated with further adverse prothrombotic and lipogenic effects.


Subject(s)
Lipids/blood , Myocardial Infarction/blood , Smoking/adverse effects , Aged , Apolipoproteins B/blood , Cholesterol/blood , Female , Fibrinogen/analysis , Humans , Logistic Models , Male , Middle Aged , Myocardial Infarction/epidemiology , Smoking/epidemiology , Time Factors
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