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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Venous thrombo-embolism is a common complication in patients with acute ischaemic stroke. Without prophylaxis, deep vein thrombosis occurs in 60-75% of patients with dense hemiplegia, usually in the paralyzed limb, and 1-2% suffer fatal pulmonary embolism. Orgaran (Org 10172, low-molecular-weight heparinoid) has been evaluated for the prevention of deep vein thrombosis in patients with acute ischaemic stroke in two studies. In a double-blind study, 75 patients were randomized to receive Orgaran (50 patients) in a loading dose of 1,000 anti-Xa units intravenously followed by 750 anti-Xa units subcutaneously 12-hourly or placebo (25 patients). Deep vein thrombosis occurred in 2 of 50 (4%) in the Orgaran group and 7 of 25 (28%) in the placebo group (p = 0.005). The corresponding rates for proximal deep vein thrombosis were 0 and 16%, respectively (p = 0.01). There was one major haemorrhage in the treated group and one minor haemorrhage in the placebo group. In the second study, the safety and efficacy of Orgaran was compared with unfractionated heparin in the prevention of deep vein thrombosis in a double-blind randomized trial. Eighty-seven patients with marked lower limb paralysis secondary to stroke were randomized to receive Orgaran (45 patients) in a dose of 750 anti-factor Xa units subcutaneously 12-hourly or unfractionated heparin (42 patients) in a dose of 5,000 units subcutaneously 12-hourly. Venous thrombosis occurred in 4 of 45 (8.9%) of the Orgaran group and 13 of 42 (31%) in the unfractionated heparin group (2p = 0.014). The corresponding rates for proximal vein thrombosis were 4.4 and 11.9%, respectively (2p = 0.255).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Orgaran in the prevention of deep vein thrombosis in stroke patients. 137 69

An intravenous infusion of a low molecular weight heparinoid, with a reduced risk of hemorrhage, may be an alternative to heparin in the management of acute ischemic stroke. To evaluate this hypothesis, we studied the safety of the heparinoid, ORG 10172, in a dose-escalation study in 26 patients. The drug was administered as a loading bolus followed by a 7-day infusion in five rates with target anti-factor Xa levels from 0.2 to 1.0 U/ml. The drug was well tolerated; no major bleeding complications or thrombocytopenia occurred. There were no deaths or hemorrhagic transformation of cerebral infarctions. The results indicate that ORG 10172 at doses to achieve a level of 1.0 U/ml or less may be used safely in management of acute cerebral infarction.
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PMID:A dose escalation study of ORG 10172 (low molecular weight heparinoid) in stroke. 246 74

This double-blind, randomised, multicentre trial in 513 patients having elective surgery for intra-abdominal or intrathoracic malignancy compared the efficacy and safety of venous thrombosis (VT) prophylaxis using 750 anti-factor Xa units of Orgaran (a mixture of low molecular weight heparinoids) given subcutaneously (sc) twice-daily with that of twice-daily injections of 5,000 units standard heparin. The main study endpoints were the development of postoperative VT detected by 125I-fibrinogen leg scanning, and the onset of clinically significant venous thromboembolism or bleeding. "Intent to treat" analysis showed a statistically non-significant trend towards less VT during Orgaran prophylaxis (10.4%) than after heparin (14.9%) and there was no difference in bleeding complications between the two study groups. Results remained similar if only patients who completed the intended course of therapy ("compliant patients") were analysed. Other trials have shown that Orgaran prevents VT after hip surgery and stroke. We now show it is also safe and effective in patients having major surgery for cancer.
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PMID:Orgaran (Org 10172) or heparin for preventing venous thrombosis after elective surgery for malignant disease? A double-blind, randomised, multicentre comparison. ANZ-Organon Investigators' Group. 750 9

Management of thromboembolic disease involves administration of anticoagulants, thrombolytics or antiplatelet agents to lyse or prevent thrombus extension. Despite widespread use and decades of experience with some of these agents, much is unknown about the effects of dose and plasma concentration on patient response. Unfractionated heparin (UFH) improves outcome in many thromboembolic disorders when administered to a target activated partial thromboplastin time (aPTT) or plasma heparin concentration. UFH exhibits dose-dependency both with absorption from subcutaneous sites and elimination. Doses based on bodyweight or estimated blood volume attain therapeutic aPTTs faster than fixed or standard doses. Low molecular weight heparins (LMWHs) were developed to increase the anti-factor Xa:anti-factor IIa activities. Several different LMWHs are as effective as UFH in treating deep venous thrombosis. Evidence fails to support a relationship between anti-factor Xa activity and either thrombosis evolution or bleeding. No comparisons have been made between bodyweight-based and anti-factor Xa activity-based doses. The dose of orally administered warfarin is adjusted to achieve a target International Normalised Ratio (INR). Maintenance doses are estimated on the basis of the patient's INR during the first 3 days of therapy: the dose required to achieve an optimal INR decreases with age > 50 years. The thrombolytic agents are administered in standard doses to achieve rapid thrombolysis with minimal alteration in systemic haemostasis. Accelerated intravenous alteplase may result in the highest rate of coronary artery reperfusion. Nevertheless, standard doses of streptokinase, anisoylated plasminogen streptokinase complex and alteplase result in similar 1-month mortality rates. The minimal advantage seen with alteplase is offset by higher rates of stroke. Future trials will focus on administration strategies achieving rapid thrombolysis, while minimising the risk of serious bleeding. With the antiplatelet agents, unpredictability in the pharmacokinetic parameters of different products has confounded interpretation of published reports. Optimal aspirin (acetylsalicylic acid) administration would include administration of an initial dose of 160 to 325mg after an acute vascular event, followed by maintenance dosages of approximately 75 mg/day for prophylaxis or treatment. Ticlopidine does not exhibit a relationship between either plasma concentration or dose and adverse effects, while pharmacodynamic effects may be dose-, but not plasma concentration-, dependent. The correlation between the concentration of dipyridamole and some of its antiplatelet effects may be the strongest amongst all the antiplatelet agents. However, unfortunately all clinical trials used standard doses and the current consensus is that dipyridamole alone is not an effective antiplatelet agent.
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PMID:Pharmacokinetic optimisation of the treatment of embolic disorders. 771 62

The use of first generation plasminogen activators, urokinase, streptokinase and tissue plasminogen activator has revolutionized thrombolytic therapy for myocardial infarction and ischaemia, and potentially stroke. However, thrombolytic therapy employing these activators is limited by reocclusion of the very arteries being opened, which follows in a small but significant number of patients. The development of second generation plasminogen activators, e.g. staphylokinase and anisoylated plasminogen streptokinase activator complex, has not alleviated the problems encountered with classical plasminogen activators. It is now widely recognized that aberrant platelet aggregation induced primarily by thrombin, rather than plasmin, is one of the major causes of recurrent thrombosis following pharmacologic thrombolysis. Agents that (a) inhibit enzymatic and/or coagulant activity of thrombin, (b) block binding of thrombin to its receptor, and (c) interfere with the generation of thrombin by the prothrombinase complex may compromise haemostasis resulting in haemorrhage. We recently demonstrated that thrombin-induced platelet aggregation is accompanied by cleavage of aggregin, a putative ADP-receptor on the platelet surface, and that these events are indirectly mediated by intracellularly activated calpain expressed on the surface. In this review, we discuss the known mechanisms of thrombin-induced platelet aggregation and suggest relative advantages of potential pharmacological agents, being developed in our laboratory, over those that have been previously developed and tested. These inhibitors selectively prevent aggregation of platelets induced by thrombin by inhibiting calpain expressed on the surface. Moreover, one of these inhibitors which blocks thrombin-induced platelet aggregation does not interfere with other platelet responses mediated by thrombin or platelet aggregation induced by other agonists, such as, ADP, collagen, phorbol myristate acetate and thromboxane A2 mimetics. This selectivity could reduce the chances of perturbing the formation of a haemostatic plug.
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PMID:Reocclusion after thrombolytic therapy: strategies for inhibiting thrombin-induced platelet aggregation. 832 74

Nadroparin (nadroparin calcium) is a low molecular weight heparin with a mean molecular weight of 4.5 kD. Compared with unfractionated heparin (UFH), nadroparin has a greater ratio of anti-factor Xa to anti-factor Ha activity, greater bioavailability and a longer duration of action, allowing it to be administered by subcutaneous injection for prophylaxis or treatment of thromboembolic disorders. In clinical trials conducted in older patients (mean age usually > 60 years), nadroparin was at least as effective as UFH in preventing deep vein thrombosis (DVT) and pulmonary embolism after major general or orthopaedic surgery, and in bedridden medical patients. Nadroparin was also at least as effective as dalteparin or oral acenocoumarol in preventing thromboembolic events following general and orthopaedic surgery, respectively. When used for treatment of established DVT, nadroparin was at least as effective as intravenous UFH. Subcutaneous nadroparin, at dosages similar to those used for the treatment of DVT, produced promising results in older patients with pulmonary embolism, acute ischaemic stroke or unstable angina. In 1 study, 75% of nadroparin-treated patients were able to complete their treatment at home and 36% did not require admission to hospital; the potential pharmacoeconomic implications of these results deserve further evaluation. Overall treatment costs (drug acquisition and monitoring costs) were similar for nadroparin and UFH in a French study, but nadroparin was associated with significantly less nursing time spent on treatment delivery. Nadroparin is well tolerated by older patients. The most frequently reported adverse events in a large (n approximately 4500) placebo-controlled study in general surgical patients were wound and injection site haematoma (11.8 and 10.2%, respectively, vs approximately 6.5% for placebo). When used as prophylaxis, no significant differences in bleeding complications were noted between nadroparin and UFH or acenocoumarol recipients. Prophylactic nadroparin was associated with significantly fewer withdrawals because of adverse events than UFH in elderly bedridden medical patients. When used as treatment for DVT, nadroparin was generally associated with lower occurrences of major bleeding than intravenous UFH (0.5 to 2.3% vs 2 to 5%); however, trials were not large enough to demonstrate any significant differences between the 2 agents. Similarly, the incidence of thrombocytopenia was slightly, but generally not significantly, lower in nadroparin (< 1%) than in UFH (< or = 3.5%) recipients. Thus, nadroparin should be considered an effective and well tolerated alternative to UFH for prophylaxis and treatment of DVT in older patients, with the advantage of more convenient administration and decreased monitoring requirements.
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PMID:Nadroparin calcium. A review of its pharmacology and clinical use in the prevention and treatment of thromboembolic disorders. 910 90

Several new drugs for the management of thromboembolic disorders have recently become available. Low-molecular-weight heparins are being evaluated for the prophylaxis of medical and surgical deep venous thrombosis and pulmonary embolism; for the treatment of pre-existing thrombosis; and for cases of coronary syndrome (unstable angina, myocardial infarction), thrombotic and ischemic stroke, interventional cardiology, pregnancy, cancer, and transplantation-associated thrombosis. A chemically synthesized heparin pentasaccharide, which has purely anti-factor Xa activity and does not induce thrombocytopenia, is also in clinical trial. Thrombin inhibitors, such as hirudin and argatroban, are a practical anticoagulant substitute where heparin cannot be used. They are also useful for the management of coronary syndrome and as adjunct therapy. The antiplatelet agent ticlopidine and its analogue, clopidogrel, which does not produce blood dyscrasia, are effective for the secondary prevention of thrombotic stroke and the management of combined arterial thrombotic syndromes. Glycoprotein-targeting antibodies, synthetic derivatives, and peptides (some of which are orally bioavailable) have added a new dimension to the management of arterial thrombosis and high-risk patients having angioplasty. Plasma-derived agents, such as antithrombin III, are available for the management of thrombophilia and disseminated intravascular coagulation. Compression devices and the foot pump, alone and in combination with pharmacologic agents, have been used successfully. Combination therapy using various agents in different proportions have also been found useful. Although there is much enthusiasm in this quickly developing area and clinical trials are demonstrating the antithrombotic efficacy of the new drugs, safety considerations require additional clinical validation. Long-term outcomes and costs also need to be addressed objectively.
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PMID:Current status on new anticoagulant and antithrombotic drugs and devices. 926 11

Anticoagulant therapy has changed dramatically during the past two years. Low molecular weight heparin has substantially replaced unfractionated heparin as the parenteral anticoagulant of choice. The use of warfarin has substantially increased, especially for prevention of stroke in the setting of atrial fibrillation. It has become clear that warfarin cannot be administered effectively in an unmonitored fixed-dose fashion. The parenteral direct thrombin inhibitor desirudin was shown to be efficacious in the prevention of deep vein thrombosis in man. Small thrombin and factor Xa inhibitors with in vivo oral anticoagulant activity have been identified.
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PMID:Cardiovascular chemotherapy: anticoagulants. 973 18

The protein Z-protein Z-dependent inhibitor complex is a factor Xa inhibitor. Protein Z deficiencies have recently been described in patients with ischemic stroke. As placenta infarction leads to poor pregnancy outcome, we studied protein Z plasma concentrations in nonthrombotic, nonthrombophilic consecutive patients with unexplained pregnancy wastage. A significant amount of protein Z deficiencies was only found in the early fetal loss group (< 1 mg/L; 44 of 200, P < 10(-4)) and mainly in the case of fetal demise between the beginning of the 10th and the end of the 15th week of gestation (odds ratio, 6.7 [3.1-14.8], P < 10(-3)). These deficiencies were not due to partial vitamin K1 deficiency, and at least some of them were constitutional ones. In women, protein Z deficiency may induce an enhanced risk of severe placental insufficiency soon after the connection of maternal and fetal circulations.
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PMID:High frequency of protein Z deficiency in patients with unexplained early fetal loss. 1189 1

Although heparin-derived oligosaccharide(s) (HDO) have been clinically used for the management of neurological disorders, such as stroke and Alzheimer's disease (AD), very little information on the mechanism of their therapeutic action is known. To test the hypothesis that HDO may pass through the blood-brain barrier (BBB) to mediate their effects, a pharmacodynamic (PD) model was developed and the presence of HDO in the cerebrospinal fluid (CSF) was used as a BBB accessibility index. Rats were treated with an ultralow molecular weight (MW) heparin fragment C3 via the intravenous or subcutaneous routes at 5-10 mg/kg. At varying periods, the plasma, CSF, and brain samples were collected, and functional anti-factor Xa activities were measured to quantitate the CSF/plasma ratios (CPR) and the brain uptake. C3 showed CPR of 1.7% and 0.8% after intravenous and subcutaneous injections, respectively. These findings were verified by intravenous administration of tritium-labeled C3 followed by detection of the radioactivity in the CSF and brain homogenates. These data suggest that ultralow MW HDO may pass through the BBB.
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PMID:The blood-brain barrier accessibility of a heparin-derived oligosaccharides C3. 1206 47


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