Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0022116 (ischemia)
91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Secondary prevention of stroke and other manifestations of atherothrombosis is essential if the burden of disease associated with these events is to be reduced. Therefore, it is important to identify patients most likely to benefit from antiplatelet therapy. There is a good rationale for combining antiplatelet agents with different modes of action, since different signalling pathways contribute to platelet activation. Based on the promising results obtained with an adenosine diphosphate receptor antagonist-aspirin combination in coronary stenting, several additional trials with clopidogrel plus aspirin are ongoing. They include CURE (Clopidogrel in Unstable angina to prevent Recurrent Events, in unstable angina and non-Q-wave myocardial infarction) and COMMIT (in acute myocardial infarction), which compare clopidogrel with placebo in patients receiving aspirin, and CREDO (Clopidogrel for Reduction of Events During extended Observation), a 1-year treatment follow-up to the clopidogrel arms of the CLASSICS trial (Clopidogrel Aspirin Stent International Cooperative Study). Planned trials with clopidogrel in neurology include SPS3 (Secondary Prevention of Small Subcortical Strokes, in patients with symptomatic lacunar stroke), and MATCH (Management of Atherothrombosis with Clopidogrel in High-risk patients, in patients with stroke or transient ischaemic attack plus one additional risk factor), which will compare the efficacy of clopidogrel plus aspirin versus clopidogrel in reducing important ischaemic events. Combination therapy with an oral glycoprotein (GP) IIb/IIIa receptor antagonist plus aspirin has so far been less promising. Trials of three compounds--orbofiban, xemilofiban and sibrafiban--in combination with aspirin for secondary prevention in cardiac patients have reported increased mortality compared with aspirin alone. A similar effect was seen when sibrafiban monotherapy was compared directly with aspirin alone. Trials of newer oral GP IIb/IIIa inhibitors are under way or are planned. The combination of dipyridamole plus aspirin appears to be superior to aspirin alone for the prevention of stroke in patients with stroke or transient ischaemic attack; the effectiveness of this combination is being further investigated in ESPRIT (European/Australian Stroke Prevention in Reversible Ischaemia Trial).
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PMID:Future perspectives for optimizing oral antiplatelet therapy. 1131 19

Ischemic heart disease (IHD) represents a pathophysiologic continuum consisting of stable angina, unstable angina, non-ST-segment elevation myocardial infarction, and ST-segment elevation myocardial infarction. Patients who develop a change in their usual stable pattern of ischemia are classified as having an acute coronary syndrome, which includes patients with unstable angina, non-ST-segment elevation myocardial infarction, and ST-segment elevation myocardial infarction. Such progression from a stable to an unstable state is believed to result from disruption of an atherosclerotic plaque with subsequent platelet aggregation and thrombus formation. This, in turn, leads to the clinical manifestations of unstable angina, MI or death. Because platelets play a central role in the thrombotic complications of atherosclerosis, antiplatelet agents have been the cornerstone of the therapy for IHD. Aspirin has been the traditional antiplatelet agent, and remains the mainstay of treatment for all forms of IHD. However, aspirin is a weak antiplatelet agent and is often poorly tolerated by many patients. Clopidogrel is a new antiplatelet agent of the thienopyridine class. Clopidogrel, when used alone, and especially in combination with aspirin, has been shown to improve outcomes in patients with IHD across a variety of syndromes. However, combination therapy with aspirin and clopidogrel has been associated with an increased risk of bleeding. Therefore, despite improved outcomes, further studies are required to determine the optimal duration and dosage regimen of such combination therapy to maximize its risk-benefit ratio.
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PMID:Clopidogrel in the management of ischemic heart disease. 1271 81

Elderly patients with unstable angina pectoris/non-ST-segment elevation myocardial infarction should be hospitalized. Precipitating factors should be identified and corrected. Electrocardiogram monitoring is important. Aspirin should be given as soon as possible and continued indefinitely. Clopidogrel should given for up to 9 months in patients in whom an early noninterventional approach is planned or in whom a percutaneous coronary intervention (PCI) is planned. Clopidogrel should be withheld for 5-7 days in patients in whom elective coronary artery bypass graft surgery (CABGS) is planned. A platelet glycoprotein IIb/IIIa inhibitor should also be given in addition to aspirin, clopidogrel, and heparin in patients in whom cardiac catheterization and PCI are planned. Patients whose symptoms are not fully relieved with three 0.4-mg sublingual nitroglycerin tablets or spray taken 5 minutes apart and the initiation of an intravenous beta blocker should be treated with continuous intravenous nitroglycerin. Beta blockers and angiotensin-converting enzyme (ACE) inhibitors should be given and continued indefinitely. The benefit of long-acting nondihydropyridine calcium channel blockers is limited to symptom control. Intra-aortic balloon pump counterpulsation should be used for severe ischemia that is continuing or occurs frequently despite intensive medical therapy or for hemodynamic instability. Statins should be used if the serum low-density lipoprotein (LDL) cholesterol is >or=100 mg/dl and continued indefinitely. Enoxaparin is preferable to intravenous unfractionated heparin in the absence of renal failure and unless CABGS is planned within 24 hours. Thrombolysis is not beneficial. High-risk patients should have an early invasive strategy with CABGS or PCI performed depending on the coronary artery anatomy, left ventricular function, presence or absence of diabetes, and findings on noninvasive testing. Following hospital discharge, patients should have intensive risk factor modification with cessation of smoking, maintenance of blood pressure below 135/85 mmHg, indefinite use of statins if needed to maintain the serum LDL cholesterol <100 mg/dl, intensive control of diabetes, maintenance of optimal weight, and daily exercise. Patients should be treated indefinitely with aspirin, beta blockers, and ACE inhibitors and with clopidogrel for up to 9 months. Nitrates should be given for ischemic symptoms. Hormonal therapy should not be given to postmenopausal women.
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PMID:Treatment of unstable angina pectoris/non-ST-segment elevation myocardial infarction in elderly patients. 1457 Aug 61

Aspirin (acetylsalicylic acid) is the most widely studied and prescribed antiplatelet drug for patients at high risk of vascular disease. It affects a single pathway in the platelet activation process and provides incomplete protection against cardiovascular events. Adenosine diphosphate receptor antagonists, by blocking an alternate pathway of platelet activation, are slightly more effective than aspirin in reducing serious vascular events in patients at high risk, with similar results for the subset of transient ischaemic attack/ischaemic stroke patients. Clopidogrel is an effective and safe alternative in patients who do not tolerate aspirin, in diabetics, in hypercholesterolaemic patients, or in those with a previous history of cardiac surgery. Moreover, antiplatelet combination therapy using agents with different mechanisms of action is an attractive preventive approach. In this way, dipyridamole combined with aspirin is being tested in the European/Australian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT) in cerebrovascular disease patients. Clinical and preclinical studies have demonstrated that therapy with clopidogrel and aspirin provides synergistic antiplatelet effects. The Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE) and PCI-CURE trials demonstrate the benefit of this combination therapy in patients who suffer from unstable angina or non-Q-wave myocardial infarction treated or not by percutaneous coronary intervention. The relative risk reduction in ischaemic events in long-term use was 20%. This antiplatelet regimen was safe and well tolerated. Currently, this therapeutic option is tested in individuals with ischaemic stroke in the Management of Atherothrombosis with Clopidogrel in High-Risk Patients with Recent Transient Ischaemic Attacks or Ischaemic Stroke (MATCH) Trial.
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PMID:Antiplatelet drugs in ischemic stroke prevention: from monotherapy to combined treatment. 1469 84

Clopidogrel is a selective inhibitor of ADP-induced platelet aggregation. A large, multicenter, randomized study in 12 562 patients with acute coronary syndromes without ST-segment elevation demonstrated that treatment with clopidogrel (loading dose of 300 mg followed by once daily treatment with 75 mg) in addition to standard therapy including aspirin (75 to 325 mg/day) significantly reduced the risk of the combined endpoint of cardiovascular death, myocardial infarction or stroke compared with treatment with standard therapy. Furthermore, the composite risk of these outcomes or refractory ischemia was also significantly reduced in patients treated with clopidogrel plus aspirin. The effects of clopidogrel were independent of background treatment with cardiovascular medications and/or interventions. The risk of severe ischemia, recurrent angina or heart failure was also significantly reduced in patients receiving clopidogrel plus aspirin. There was also a significant reduction in the need for coronary revascularization during the initial period of hospitalization. In patients undergoing percutaneous coronary intervention (PCI), the relative risk of the combined endpoint of cardiovascular death, myocardial infarction or urgent target-vessel revascularization within 30 days of the intervention was significantly reduced. Moreover, the relative risk of the single endpoint of myocardial infarction within 30 days of PCI was significantly in favor of clopidogrel-treated patients. Hemorrhagic events (both major and minor) were significantly more frequent in patients with acute coronary syndromes receiving treatment with clopidogrel plus aspirin than in patients treated with aspirin alone. This was largely attributable to an increased incidence in the rate of gastrointestinal hemorrhage and bleeding at the site of arterial puncture. However, there was no difference between the two groups in the incidence of bleeding episodes that were considered to be life-threatening.
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PMID:Clopidogrel: potential in the prevention of cardiovascular events in patients with acute coronary syndromes. 1472 5

Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. Platelets may contribute to increase ischemic injury by enhancing the inflammatory response of leukocytes and endothelial myocardial cells. Pharmacological inhibition of platelet activation prevents ischemic complications in patients with coronary diseases. Agents directed against the integrin glycoprotein IIb/IIIa (GP IIb/IIIa) receptor not only inhibit platelet aggregation but also have been demonstrated to limit the inflammatory response in acute coronary syndromes. The question then raised is if the inhibition of platelet activation by other mechanisms than the blockade of GP IIb/IIIa may also exert anti-inflammatory effects. The aim of the present study was to analyze if clopidogrel may exert anti-inflammatory effects during the acute phase of myocardial infarction. A ligature was placed around the left anterior descending coronary artery of New Zealand White rabbits. After 15 min of ischemia, the myocardium was reperfused and the ischemic coronary artery was isolated 24 h after the ischemia. A group of ischemic rabbits was given a single oral dose of clopidogrel (20 mg kg(-1)) just after the arterial occlusion and the animal was recovered. Sham-operated animals served as control. P-selectin expression was significantly increased in infarcted rabbits with respect to control rabbits. Clopidogrel administration reduced P-selectin expression with respect to untreated infarcted rabbits. CD40 ligand and tissue factor expression was increased in the ischemic coronary artery and reduced after clopidogrel administration. Clopidogrel also protected endothelial nitric oxide synthase protein expression in the ischemic coronary artery, a protein that has been found downregulated under inflammatory conditions. In conclusion, inhibition of platelet activation by clopidogrel exerted anti-inflammatory effects on the ischemic coronary artery.
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PMID:Effect of clopidogrel on the expression of inflammatory markers in rabbit ischemic coronary artery. 1604 1

Ischemia and reperfusion injury is a pathologic process with serious consequences, arising due to interruption of arterial blood flow. Restored blood flow achieved after the ischemic period causes formation of oxygen radicals by activation of a variety of substances and systems. In this study, we investigated the effect of clopidogrel, an antithrombocyte agent, on tissue nitric oxide (NO) levels in an experimental ischemia reperfusion model. For this purpose, 6 hours of ischemia and 4 hours of subsequent reperfusion were applied to the right lower extremities of the subjects. Clopidogrel therapy was started in one of these groups 10 days before the process (study group). NO levels were measured in all groups in the muscle, lung, and liver tissues, and in plasma. Lung, plasma, and liver NO measurement values had statistically significant differences among the groups. There was no statistically significant difference in the measurements made on the muscle tissue. Clopidogrel, which has previously been reported to be suitable to be used as a preventive agent of ischemia reperfusion damage, has had a reducing effect on the NO levels in tissues in the ischemia reperfusion model created in our present study.
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PMID:Effect of clopidogrel on nitric oxide levels in an ischemia reperfusion model. 1689 7

The specific thromboxane receptor antagonist, S18886, was evaluated for prevention of coronary arterial thrombosis and myocardial ischemia-reperfusion in anesthetized canines. For the primary thrombosis study in left circumflex (LCX) coronary artery, 26 dogs were randomized to receive either vehicle (n = 7) or intravenous S18886 (0.3 mg/kg, n = 6; 1.0 mg/kg, n = 6; and 3.0 mg/kg, n = 7). The respective times to occlusion after S18886 were as follows: 56.8 +/- 9.3, 83.5 +/- 14.9, and 92.4 +/- 15.7 minutes compared to 43.3 +/- 8.2 minutes after vehicle. S18886 caused a minimal increase in tongue bleeding time and a significant decrease in ex vivo platelet aggregation to arachidonic acid or U46619. Another 37 dogs were randomized to receive placebo (n = 12), clopidogrel 1.0 mg/kg p.o. QDX3 (n = 9), clopidogrel + S18886 0.3 (n = 9) or 1.0 (n = 7) mg/kg intravenous. Clopidogrel produced a 50% reduction in adenosine diphosphate-induced platelet aggregation and a slight increase in the time to occlusion. However, clopidogrel + S18886 1.0 mg/kg prevented occlusive thrombus formation in most of the coronary vessels over 6 hours. S18886 did not alter myocardial infarct size in the ischemia-reperfusion model. In conclusion, S18886 alone caused a dose-dependent prolongation in the time to primary occlusive coronary artery thrombosis, whereas S18886 + clopidogrel displayed effective in preventing occlusive thrombus formation with only a moderate increase of tongue-bleeding time.
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PMID:Preclinical evaluation of S18886 in an experimental model of coronary arterial thrombosis. 1711 Aug 6

The Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis in Myocardial Infarction 28 (CLARITY-TIMI 28) trial was a randomized, double-blind, placebo-controlled study of clopidogrel in 3,491 patients receiving fibrinolytic therapy for ST-segment elevation myocardial infarction. Patients were randomized to clopidogrel or placebo begun at the time of fibrinolysis. This analysis reports the outcomes among the 136 patients in the trial population who underwent coronary artery bypass grafting (CABG) during the index hospitalization. There was no difference in the rates of TIMI major or minor bleeding between the clopidogrel and placebo groups from randomization to the end of follow-up (13.6% vs. 14.3%, P = 1.0) or from the time of CABG to the end of follow-up (9.1% vs. 11.4%, P = 0.78). When any day for study medication discontinuation < or = 5 days prior to CABG was chosen as a cut point to evaluate bleeding risk for clopidogrel vs. placebo, there was no excess bleeding in the clopidogrel group. Among patients undergoing CABG, there was a trend toward reduction in the risk of cardiovascular death, recurrent MI, or recurrent ischemia requiring urgent revascularization at 30 days for those taking clopidogrel (OR 0.66, 95% CI 0.27-1.5; P = 0.37), consistent with the benefit seen in the overall trial population (OR 0.80, CI 0.65-0.97; P = 0.03). In conclusion, early clopidogrel treatment among CLARITY-TIMI 28 patients undergoing CABG was not associated with an increase in the rate of peri-operative bleeding and showed a trend toward reduction in 30-day ischemic events.
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PMID:Benefits and risks of clopidogrel pretreatment before coronary artery bypass grafting in patients with ST-elevation myocardial infarction treated with fibrinolytics in CLARITY-TIMI 28. 1732 34

Comparative efficacy of surgical and therapeutic methods of repeated ischemic stroke prophylaxis at the patients with clinical symptoms of acute brain ischemia and carotid stenosis less 70% was analyzed. Three-year period of follow-up demonstrated that at the patients who have undergone carotid endarterectomy the repeated ischemic events were seen only at 4 (3.9%), and in the group of therapeutic prophylaxis--at 57 (52.7%). Carotid endarterectomy permits to reduce relative risk of repeated ischemic stroke from 0.77 in therapeutic prophylaxis to 0.07 in surgical treatment. Antiaggregant therapy after surgery is mandatory. Prolonged administration of Clopidogrel permits to reduce restenosis and thrombotic complication rate.
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PMID:[Efficacy of surgical and therapeutic methods of repeated carotid ischemic stroke prophylaxis]. 1741 82


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