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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clopidogrel is a new thieno-pyridine derivative and has a more potent inhibitory effect on platelet aggregation, dependent on ADP rather than ticlopidine. In a phase I study performed in Japan, significant inhibition of ADP-induced platelet aggregation and prolongation of bleeding time was observed in the dose range of 25, 50 and 75 mg. These effects were comparable to 200 or 300 mg of ticlopidine. Antithrombotic effects have also been shown in experimental animal models. Clopidogrel is expected to reduce the incidence of neutropenia since smaller doses are sufficient to suppress platelet aggregation compared to ticlopidine. Clopidogrel has been proven to be a potent and well-tolerated antiplatelet agent for atherosclerosis patients at risk of thrombosis, in Europe.
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PMID:[Antiplatelet effect of clopidogrel]. 161 93

The anti-aggregating activity of five rising doses of clopidogrel has been compared to that of ticlopidine in atherosclerotic patients. The aim of this study was to determine the dose of clopidogrel which should be tested in a large scale clinical trail of secondary prevention of ischemic events in patients suffering from vascular manifestations of atherosclerosis [CAPRIE (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events) trial]. A multicenter study involving 9 haematological laboratories and 29 clinical centers was set up. One hundred and fifty ambulatory patients were randomized into one of the seven following groups: clopidogrel at doses of 10, 25, 50, 75 or 100 mg OD, ticlopidine 250 mg BID or placebo. ADP and collagen-induced platelet aggregation tests were performed before starting treatment and after 7 and 28 days. Bleeding time was performed on days 0 and 28. Patients were seen on days 0, 7 and 28 to check the clinical and biological tolerability of the treatment. Clopidogrel exerted a dose-related inhibition of ADP-induced platelet aggregation and bleeding time prolongation. In the presence of ADP (5 microM) this inhibition ranged between 29% and 44% in comparison to pretreatment values. The bleeding times were prolonged by 1.5 to 1.7 times. These effects were non significantly different from those produced by ticlopidine. The clinical tolerability was good or fair in 97.5% of the patients. No haematological adverse events were recorded. These results allowed the selection of 75 mg once a day to evaluate and compare the antithrombotic activity of clopidogrel to that of aspirin in the CAPRIE trial.
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PMID:Platelet anti-aggregating activity and tolerance of clopidogrel in atherosclerotic patients. 897 14

Arterial thrombosis frequently leads to death or disability from stroke, peripheral arterial disease, or myocardial infarction (MI). Treating the underlying causes of these diseases is the key to producing significant reduction in morbidity, mortality, and health care costs. Prevention of arterial thrombosis is the primary indication for antiplatelet therapy, and intense research has been conducted in the past decade to develop novel antiplatelet agents with favorable safety profiles. The results of the Antiplatelet Trialists' Collaboration, which definitively established the rationale for antiplatelet agents in the prevention of death, MI, and stroke, were an important stimulus for this research. This large meta-analysis combined data from 145 randomized trials and showed that antiplatelet therapy (most commonly aspirin, 75 to 325 mg/d) reduced the risk of vascular events, including nonfatal MI, nonfatal stroke, and vascular death, by 25% in patients at high risk for occlusive vascular disease. The limitations and adverse effects associated with traditional antiplatelet agents such as aspirin have prompted the search for newer antiplatelet agents. Clinical trials such as the Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) study, which was the first study to evaluate aspirin and clopidogrel in patients with cerebrovascular, cardiac, and peripheral arterial disease, have established the importance of newer antiplatelet effects in the management of patients with diseases associated with atherosclerosis. The pathophysiology of atherosclerosis, the mechanisms of action of antiplatelet agents, and the results of these and other clinical trials that document the value of antiplatelet agents in atherosclerosis are reviewed in this paper.
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PMID:Antiplatelet therapy in atherosclerotic cardiovascular disease. 958 29

The risk factors, epidemiology, diagnosis, and treatment of peripheral arterial disease are reviewed. Peripheral arterial disease is characterized by a gradual reduction in blood flow to one or more limbs secondary to atherosclerosis. Risk factors include smoking, diabetes mellitus, hyperlipidemia, and hypertension. The most common clinical manifestation is intermittent claudication. The prevalence of intermittent claudication in people over the age of 50 is 2-7% for men and 1-2% for women. The ankle:brachial pressure index (ABPI) is a useful measure of disease severity; an ABPI of 0.5-0.9 is common in intermittent claudication. The goals of therapy are to relieve or reduce ischemic symptoms, alleviate disability, improve in functional capacity, prevent progression that may result in gangrene and limb loss, and prevent cardiovascular and cerebrovascular events. Treatment includes risk-factor modification, drug therapy (primarily with antiplatelet agents), and revascularization procedures. Aspirin has been shown to be effective in reducing the associated risk of myocardial infarction and stroke. Ticlopidine appears to be a reasonable alternative for patients who are hypersensitive to aspirin. Clopidogrel has been shown to be more effective than aspirin in patients with recent myocardial infarction, recent stroke, or established peripheral arterial disease. There is controversy over the appropriate treatment for acute arterial occlusions. Risk-factor modification and antiplatelet drugs are the mainstays of therapy for patients with intermittent claudication, the most common manifestation of peripheral arterial disease.
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PMID:Management of peripheral arterial disease. 978 99

The recent CAPRIE trial (clopidogrel versus aspirin in patients at risk of ischaemic events) compared clopidogrel with aspirin in reducing the risk of vascular events in 19,185 patients with clinical manifestations of atherosclerosis. Participants were randomized to receive daily oral clopidogrel (75 mg) or aspirin (325 mg). Treatment periods ranged from 1 to 3 years. The primary outcome measurement was an aggregate of myocardial infarction, ischemic stroke and vascular death. Event rates of 5.32% and 5.83% were associated with clopidogrel and aspirin therapy, respectively. Clopidogrel therapy resulted in a relative risk reduction of 8.7% (CI 0.3-16.5%) compared with aspirin therapy (p = 0.043). Gastrointestinal hemorrhages occurred in 1.99% of patients treated with clopidogrel and 2.66% of patients treated with aspirin (p < 0.002). There were no significant treatment-based differences in the rates of intracerebral hemorrhages and hemorrhagic deaths or thrombocytopenia. These results indicate that clopidogrel is more effective and safer than aspirin in reducing adverse cardiovascular events in patients with atherosclerosis.
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PMID:Results of the CAPRIE trial: efficacy and safety of clopidogrel. Clopidogrel versus aspirin in patients at risk of ischaemic events. 989 20

The safety and pharmacodynamic compatibility of clopidogrel with medications commonly used in patients with atherosclerosis, such as, a beta-adrenergic receptor antagonist (atenolol) and a calcium uptake inhibitor (nifedipine) were assessed. Atenolol and nifedipine interactions with clopidogrel were studied in patients with peripheral arterial obstructive disease taking a well-established regimen of nifedipine (N group of 6 patients) and in patients with coronary artery disease taking a well-established regimen of either atenolol (A group of 8 patients) or of atenolol and nifedipine (AN group of 8 patients). The study was conducted as a double-blind, randomized, crossover comparison of clopidogrel, 75 mg once daily, and placebo treatment for 7 days, with a 14-day washout between treatments. Pharmacodynamic interactions between atenolol and nifedipine, either alone or in combination, and clopidogrel were assessed primarily on the clinical control of angina or hypertension and, secondarily, by comparing the extent of inhibition of ADP (5 microM)-induced platelet aggregation achieved between the 3 groups. The mean number of anginal episodes per patient during the placebo week was 1.50, 9.0 and 11.5 in the A, N and AN groups, respectively; during the week of clopidogrel treatment, it was 1.39, 7.3 and 9.0, respectively, indicating no change in occurrence. Likewise, review of the use of nitrates (long or short acting) did not suggest any major change in usage during any period of the study. ECGs did not change between the three recording times (at screening and at the end of each treatment period). Vital signs were also unchanged throughout. Percent inhibition of platelet aggregation on day 7 was 31% in the N group, 39% in the A group, 28% in the AN group, and 33% overall. In conclusion, the coadministration of clopidogrel did not interfere with the clinical control of hypertension or angina established with atenolol or nifedipine, or both. Clopidogrel retained its full antiplatelet effect, and there were no safety problems caused by the coadministration.
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PMID:Clopidogrel compatibility with concomitant cardiac co-medications: a study of its interactions with a beta-blocker and a calcium uptake antagonist. 1044 Apr 25

Clopidogrel, a new platelet ADP receptor antagonist, is more effective than aspirin in reducing the risk of subsequent vascular ischemic events in patients with a broad spectrum of symptomatic atherosclerosis (recent ischemic stroke, recent myocardial infarction, or symptomatic peripheral arterial disease). In CAPRIE (clopidogrel versus aspirin in patients at risk of ischemic events), a randomized, blinded, active control trial in 19,185 high-risk patients, clopidogrel reduced the combined risk of ischemic stroke, myocardial infarction or vascular death by 8.7% compared with aspirin (p = 0.043). The CAPRIE cohort had a mean age of 62.5 years, which was reflected in the high proportion of patients who had medical conditions other than symptomatic atherosclerosis, and in the extensive use of concurrent therapies, including commonly used cardiovascular drugs. For all concomitant medications analysed, there was no evidence of statistically or clinically significant interactions with clopidogrel. The CAPRIE data confirm the findings of earlier clinical studies, which suggested that clinically significant drug interactions with clopidogrel are rare, that it can safely be prescribed with a range of other drugs (including phenobarbital, cimetidine, estrogen, digoxin, theophylline, atenolol, nifedipine, or nifedipine-atenolol in combination), and that the clinically proven dose of 75 mg once daily is suitable for all age groups studied. Moreover, CAPRIE demonstrated that there is no need for an adjustment of clopidogrel dose on the basis of gender, weight or race, and that there is no need for routine hematological monitoring. Additional clinical pharmacology studies have shown that the absorption of clopidogrel is unaffected by food or antacids, and that no dose adjustment is necessary in patients with renal impairment or with mild-to-moderate hepatic impairment. Due to pharmacologic considerations and limited clinical data, clopidogrel should be used cautiously with heparin, warfarin or non-steroidal anti-inflammatory drugs. With a simple regimen of 75 mg once daily indicated for all patients, clopidogrel combines a favorable risk/benefit ratio with ease of use in clinical practice.
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PMID:Clinical aspects of the use of clopidogrel, a new antiplatelet agent. 1044 Apr 29

Ischemic stroke, myocardial infarction and peripheral arterial disease are different clinical manifestations commonly due to the same underlying disease, i.e. atherosclerosis with subsequent thrombosis/embolism (atherothrombosis). Many clinical trials of secondary prevention after stroke or TIA have evaluated the benefit of long-term use of antiplatelet drugs in reducing the risk of subsequent vascular events. Aspirin and triclopidine have been shown to be effective in placebo-controlled studies for the composite outcome of stroke, myocardial infarction, or vascular death. Contrasting with these benefits, there were potentially serious, though rare, adverse effects. These considerations certainly justify the development of new antiplatelet agents. Clopidogrel is a new ADP-receptor antagonist, with a greater activity in animal models of thrombosis. CAPRIE (Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events) was a randomized, blinded, international trial designed to assess the relative efficacy of clopidogrel and aspirin in reducing the risk of the outcome cluster of ischemic stroke, myocardial infarction, or vascular death, as well as to assess their relative safety. 19,185 patients were recruited. The intention-to-treat analysis showed that the relative risk reduction was 8.7% (95% CI 0.3-16.5, p = 0.043) in favor of clopidogrel from an overall annual event rate of ischemic stroke, myocardial infarction, or vascular death, ranging from 5.83% in the aspirin group to 5.33% in the clopidogrel group. The percentage of adverse events reported was higher in the aspirin group for all categories except rash, diarrhea, and abnormal liver function. It seems likely that clopidogrel will replace ticlopidine for stroke prevention, because of its better safety profile, and comparable efficacy. Clopidogrel probably will not replace aspirin as the first line therapy for many clinicians because of its higher cost and lack of widespread experience. However, other clinicians have already decided that they will use clopidogrel as first choice, because of the significant advantage over aspirin demonstrated in the CAPRIE study.
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PMID:Clopidogrel for cerebrovascular prevention. 1047 7

Antiplatelet drugs have been demonstrated to reduce the incidence of myocardial infarction (MI), stroke or vascular death in patients with vascular disease. There are no data suggesting that antiplatelet therapy acts differently in older people than in younger people and recommendations based on randomised clinical trials are probably generalisable to older people. Aspirin (acetylsalicylic acid) has been shown to reduce the incidence of non-fatal MI, nonfatal stroke and vascular death in patients with acute MI, a previous MI, angina pectoris or peripheral occlusive arterial disease (POAD), and to reduce cardiovascular morbidity and mortality in patients with a prior ischaemic stroke or transient ischaemic attack (TIA). It has also been shown to reduce the incidence of thrombus formation after coronary artery bypass graft surgery and percutaneous transluminal angioplasty, and in patients with atrial fibrillation and heart valve replacements. Deep vein thrombosis and pulmonary embolism after surgery are also prevented by aspirin. The available data allows the following recommendations to be made. Aspirin 160 to 325 mg daily should be administered to older men and women without contraindications to aspirin who have acute MI, prior MI, unstable or stable angina pectoris, ischaemic stroke, TIA or POAD, and continued indefinitely to reduce the risk of MI, stroke or vascular death. Aspirin should be started in patients before or immediately after revascularisation, and after heart valve replacement. Older men and women with nonvalvular atrial fibrillation who have contraindications to oral anticoagulant therapy but no contraindications to aspirin should be treated with aspirin 325 mg daily. It is reasonable to treat older men and women without contraindications to aspirin with aspirin 160 to 325 mg daily if they are at high risk for developing new coronary events. The incidence of stroke, MI or vascular death in patients after a stroke or TIA is reduced by ticlopidine. Therefore, ticlopidine 250 mg twice daily may be used in older men and women with a history of stroke or TIA who do not respond to or who cannot tolerate aspirin. Patients at high risk for coronary artery stent thrombosis benefit from combined therapy with aspirin plus ticlopidine. The annual incidence of ischaemic stroke, MI or vascular death was significantly reduced by clopidogrel in the Clopidogrel versus Aspirin in Patients at Risk of Ischemic Events (CAPRIE) trial. Therefore, clopidogrel 75 mg daily may be used in older men and women with symptomatic atherosclerosis who do not respond to or who cannot tolerate aspirin to reduce the incidence of ischaemic stroke, MI or vascular death. It should be noted that the acquisition cost for either ticlopidine or clopidogrel is considerably greater than that for aspirin. Most data indicate that the combination of aspirin and dipyridamole is not more effective than aspirin alone in preventing vascular events, and available data do not support the use of sulfinpyrazone in patients with vascular disease.
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PMID:Antiplatelet agents in the prevention of cardiovascular morbidity and mortality in older patients with vascular disease. 1049 69

The role of the platelet and the endothelium in the pathogenesis of atherosclerosis and subsequent ischemic events has been the subject of extensive investigation. Arterial sites where endothelial function is severely impaired are often the sites of atheroma development. Lesion evolution impairs endothelial function, leading to a self-perpetuating cycle of growth. During early lesion development, overt thrombotic events are rare. However, rupture of an advanced, necrotic plaque or intimal ulceration triggers arterial thrombosis, at which point the importance of platelet function may be seen clearly. The Antiplatelet Trialists' Collaboration meta-analysis demonstrated the benefit of antiplatelet therapy to patients with atherosclerotic disease. Aspirin is the most widely studied agent and is considered the standard of antiplatelet therapy. Newer agents that intervene at different stages of the platelet activation pathway have been developed. Clopidogrel, a new adenosine diphosphate receptor antagonist, is more effective than aspirin in reducing vascular events in patients with prior myocardial infarction, stroke, or established peripheral arterial disease. The glycoprotein IIb-IIIa antagonists such as abciximab have proven effective in the setting of active arterial thrombosis and percutaneous revascularization, but their value in secondary prevention remains unknown. All patients with atherosclerosis should be treated with an antiplatelet drug. Current evidence suggests that either aspirin or clopidogrel are appropriate first-line agents. There is urgent need for an analysis of the risk/benefit ratio in various populations and clinical settings to determine the most appropriate type and intensity of therapy for a given patient.
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PMID:Platelet-endothelial interactions in atherothrombotic disease: therapeutic implications. 1055 82


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