by Antiplatelet drugs are a class of medications that are used to inhibit platelet activation and reduce thrombosis. These drugs play an important role in preventing arterial clotting and are used for several cardiovascular conditions. This article provides an overview of commonly used antiplatelet drugs, their mechanisms of action, uses and side effects.
Aspirin
Aspirin was one of the earliest antiplatelet drugs discovered and remains one of the most widely used. It works by irreversibly inhibiting the enzyme cyclooxygenase-1 (COX-1) in platelets. This action blocks thromboxane A2 synthesis, which is a potent activator of platelet aggregation and vasoconstriction.
Aspirin is commonly prescribed as a lifelong, low-dose regimen (75-325 mg) for prevention of cardiovascular events in conditions like stable coronary artery disease, cerebrovascular disease and peripheral vascular disease. It has been shown to reduce risks of heart attack, stroke and cardiovascular death when taken regularly.
Side effects of aspirin include gastrointestinal upset like dyspepsia, ulcers and bleeding. Rarely, it can cause Reye’s syndrome in children recovering from viral infections. Overdose of aspirin can potentially lead to metabolic acidosis and salicylate poisoning.
Clopidogrel
Clopidogrel is a thienopyridine class of Antiplatelet Drugs . It works by irreversibly inhibiting the P2Y12 receptor on platelets, which is vital for stable platelet adhesion and aggregation. This action prevents ADP-induced platelet activation and clotting.
Clopidogrel is commonly used in patients with coronary artery disease undergoing percutaneous coronary intervention (PCI) with stent placement. It is also used for recent ischemic stroke or myocardial infarction to reduce risks of recurrent events.
Bleeding is the major side effect of clopidogrel. Other rare side effects include diarrhea, rash, nausea. Due to irreversible mechanism, its antiplatelet effects last for the life of the platelet (7-10 days), which means its effects cannot be rapidly reversed.
Prasugrel
Prasugrel is another thienopyridine similar to clopidogrel but with more potent antiplatelet activity due to higher affinity for P2Y12 receptors. It gets converted to active metabolites faster than clopidogrel.
Prasugrel has been shown to reduce risks of ischemic events even more than clopidogrel in patients undergoing PCI. However, it also increases major bleeding risks more than clopidogrel. Hence prasugrel is generally reserved for select high risk patients who do not respond adequately to clopidogrel.
Bleeding is the major side effect as with other thienopyridines. Due to irreversible binding, its effects also last for the life of the platelet and cannot be quickly reversed.
Ticagrelor
Ticagrelor is a direct-acting and reversible P2Y12 receptor antagonist. In contrast to thienopyridines, it does not require metabolic activation and binds reversibly to the receptor.
Ticagrelor has shown benefits over clopidogrel in reducing risks of heart attack, stroke and death in patients with acute coronary syndromes or prior myocardial infarction. Some cardiologists prefer ticagrelor over prasugrel due to more predictable platelet inhibition and potentially safer bleeding profile.
However, ticagrelor can increase risks of non- fatal bleeding including intracranial hemorrhage. Other side effects include dyspnea and gastrointestinal disturbances. Being reversible, its effects can be titrated quickly in emergencies of bleeding or prior to surgery.
Dual Antiplatelet Therapy
For optimum protection against arterial clotting, current guidelines recommend dual antiplatelet therapy with aspirin and a P2Y12 receptor blocker like clopidogrel, prasugrel or ticagrelor in coronary artery disease patients.
Following an acute coronary syndrome or stent implantation, guidelines recommend at least 12 months of dual therapy. However, risks of bleeding need to be carefully balanced, especially in elderly patients. Newer antiplatelet agents with less bleeding risks are still needed.
Antiplatelet drugs like aspirin, clopidogrel, prasugrel and ticagrelor play an important role in prevention and management of various cardiovascular conditions. Their mechanisms of action, uses, benefits and side effects were overviewed. With advances, safer antiplatelet agents with reversible binding and fewer bleeding complications are being developed.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it
