Antiplatelet agent

PE His initial vital signs were significant for BP 210/120 mm Hg, HR 80 beats/min, RR 18 breaths/min, and O2 saturation 98% on 6 liters oxygen by nasal cannula. In the ED, PB was started on IV infusions of nitroglycerin, metoprolol, and heparin. The patient was ruled in for acute Ml, with first creatine kinase (CK) of 137 lU/L, then peaking to 467 lU/L. Troponin was elevated at 0.95. ECG showed an ST segment elevation with no Q wave. 

What is the role of platelet aggregation in acute coronary syndromes  

What is the final common pathway in platelet aggregation  

What is the mechanism of action for glycoprotein llb/llla inhibitors  

Platelet aggregation plays an important role in the pathogenesis of acute coronary syndromes (ACS). Myocardial infarction is an ACS that occurs when atherosclerotic plaques embedded in artery walls rupture, leading to thrombus formation and coronary occlusion. Patients with high-risk coronary stenosis may need percutaneous coronary interventions (PCI) with or without stent placement to revascularize the arteries. 

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Two general methods of improving polymer hemocompatibility are known (1) grafting of hydrophilic chains, and (2) the chemical attachment of an antiplatelet agent. In this respect, many hydrophilic and other monomers are grafted on solid polyurethane surfaces such as... 

Polymers with an antiplatelet agent of 5-(6-carboxyl-hexyl) l-(3-cyclohexyl-3-hydroxyropyl) hydantoin as an end group were synthesized by esterifying the hydantoin molecule with a haloalcohol, such as CCI3CH2OH or BrCH2CH20H, and using the product as coinitiator with... 

Shi D, Yang J, Yang D, LeCluyse EL, Black C, You L, Akhlaghi F, Yan B (2006) Anti-influenza prodrug oseltamivir is activated by carboxylesterase human carboxylesterase 1, and the activation is inhibited by antiplatelet agent clopidogrel. J Pharmacol Exp Ther 319 1477-1484... 

The Cochrane group examined (a) whether the addition of UFH or LMWH to antiplatelet agents offers any net advantage over antiplatelet monotherapy for acute stroke, and (b) the effectiveness of anticoagulants compared to antiplatelets in acute ischemic stroke. They included 4 trials of 16,558 patients, each of which specified aspirin (160-333 mg daily) as the control, and all of which randomized patients within 14 days of stroke onset. The anticoagulants tested were UFH and LMWH. Almost 98% of the patients were followed up for 6 months. 

ACUTE STROKE THERAPY WITH OTHER ANTIPLATELET AGENTS... 

The use of other antiplatelet agents in the acute setting has not been extensively investigated. 

Finally, a Cochrane review of antiplatelet therapy following CEA found no evidence of a difference in mortality when antiplatelets were compared with placebo. However, treatment with antiplatelet agents following CEA decreased the risk of postoperative stroke (OR 0.58, 95% Cl 0.34-0.98). ... 

Berge E, Sandercock P. Anticoagulants versus antiplatelet agents for acute ischemic stroke (Review). The Cochrane Collaboration 2006. 

Gent M. A systematic overview of randomised trials of antiplatelet agents for the prevention of stroke, myocardial infarction and vascular death. In Hass WK, Easton ID, editors. Ticlo-pidine, platelets and vascular disease. New York Springer-Verlag 1993 p99-116. 

Do not combine with an antiplatelet agent o If patient experiences a systemic embolism while receiving warfarin and has a therapeutic INR, add aspirin 75-100 mg/d. For patients unable to take aspirin, then add dipyridamole 400 mg/d or clopidogel 75 mg/d. Immediate release dipyridamole needs an acidic gastric pH (<4) for adequate absorption... 

Note patients on aspirin therapy before CVA onset can still receive tPA. No recommendations are made regarding other antiplatelet agents. 

No antiplatelet agents or anticoagulants should be administered for 24 h following the completion of alteplase (tPA) infusion... 

Antiplatelet agents, anticoagulants, and invasive procedures such as the insertion of a central line or the placement of a nasogastric tube should be avoided for 24 hours after the infusion of alteplase to prevent bleeding complications. Bladder catheterization should also be avoided for 30 minutes post-infusion. 

Warfarin has not been adequately studied in non-cardioembolic stroke, but it is often recommended in patients after antiplatelet agents fail. One small retrospective study suggests that warfarin is better than aspirin.30 More recent clinical trials have not found oral anticoagulation in those patients without atrial fibrillation or carotid stenosis to be better than antiplatelet therapy. In the majority of patients without atrial fibrillation, antiplatelet therapy is recommended over warfarin. In patients with atrial fibrillation, long-term anticoagulation with warfarin is recommended and is effective in both primary and secondary prevention of stroke.12 The goal International Normalized Ratio (INR) for this indication is 2 to 3. 

The widely used platelet inhibitor aspirin or acetylsalicylic acid, by acetylating the enzyme cyclooxygenase, inhibits platelet function by preventing the formation of thromboxane A2 and the synthesis of prostaglandin I2 (PGI2) (68). Aspirin has been used in combination with other antiplatelet agents such as ticlopidine, which inhibits ADP-induced platelet aggregation (69). 

In practice, some anticoagulation agents such as heparin or antiplatelet agents, e.g. nitric oxide (NO) are delivered to sensor sites in order to reduce the risk of thrombus formation. Nitric oxide (NO), which is a potent inhibitor of platelet adhesion and activation as well as a promoter of wound healing in tissue, has been incorporated in various polymer metrics including PVC (poly(vinyl-chloride)), PDMS (poly-dimethyl-siloxane) and PU (poly-urethanes). Those NO release polymers have been tested in animals as outer protection coatings and have shown promising effects for the analytical response characteristics of the sensor devices [137],... 

Drugs used in clotting disorders Clot reducers Anticoagulants Antiplatelet agents Thrombolytics Clot facilitators... 

The AHA/ASA guidelines recommend that antiplatelet therapy as the cornerstone of antithrombotic therapy for the secondary prevention of ischemic stroke and should be used in noncardioembolic strokes. Aspirin, dopidogrel, and extended-release dipyridamole plus aspirin are all considered first-line antiplatelet agents (see Table 13-1). The combination of aspirin and clopido-grel can only be recommended in patients with ischemic stroke and a recent history of myocardial infarction or coronary stent placement and then only with ultra-low-dose aspirin to minimize bleeding risk. 

Hydrophobic polymer materials that slowly release N O can be used on the surface of medical devices. Many medical devices suffer from the surface adhesion of blood platelets. To minimize this thrombogenic effect, blood thinners such as heparin, coumarin, and aspirin are often used. However, systemic administration of antiplatelet agents could increase the risk of uncontrolled bleeding elsewhere in the body. In contrast, biocompatible polymer films would solve this problem [153]. It is possible to create polymeric surfaces that mimic the inner surface of a blood vessel by... 

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