Antiplatelets and anticoagulants are drugs involved in the process of blood clotting. Antiplatelet drugs interfere with platelet activation and aggregation while anticoagulants drugs interfere with the coagulation cascade.
1. Overview and Key Difference
2. What is Blood Clotting
3. What are Antiplatelets
4. What are Anticoagulants
5. Antiplatelet vs Anticoagulant in Tabular Form
6. Summary – Antiplatelet vs Anticoagulant
What is Blood Clotting?
Blood clotting is an extremely complex process involving platelets, clotting factors, and endothelial cells lining the blood vessels. It is an important protective mechanism that limits blood loss after trauma. It also is a critical step in wound healing because the fiber framework formed in clotting acts as the foundation onto which multiplying cells migrate. Damage to blood vessels brings blood cells and the highly reactive extracellular matrix into contact. Blood cells latch on to binding sites in the extracellular material.
Platelet activation and aggregation are the immediate results of this binding. Inflammatory mediators secreted by damaged platelets and endothelial cells activate blood cells to produce various potent chemicals. More platelets activate due to these chemicals and a platelet plug forms over the gap in the endothelium. The number and function of platelets directly correlate to the success of the process. Thrombocytopenia means low platelet number, and thrombasthenia means poor platelet function. Bleeding time is the test that assesses the integrity of the platelet plug formation. Intrinsic and extrinsic pathways are the two routes along which clotting progresses from here.
The liver produces clotting factors. Liver diseases and genetic abnormalities lead to poor production of various clotting factors. Hemophilia is such a situation. The extrinsic pathway, also known as the tissue factor pathway involves factors VII and X while the intrinsic pathway involves factors XII, XI, IX, VIII and X. Both extrinsic and intrinsic pathways lead to the common pathway which starts with the activation of factor X. Fibrin meshwork forms as a result of the common pathway and provides the aforementioned foundation for other cellular processes.
What are Antiplatelets?
Antiplatelet are drugs that interfere with platelet plug formation. In essence, these drugs interfere with platelet activation and aggregation. These drugs may be used as prophylaxis for clot formation, to treat acute thrombotic events and as anti-inflammatory drugs. Cyclooxygenase inhibitors, ADP receptor inhibitors, phosphodiesterase inhibitors, glycoprotein IIB/IIA inhibitors, thromboxane inhibitors and adenosine reuptake inhibitors are a few known drugs classes. Gastrointestinal bleeding is the commonest side effect of these drugs.
What are Anticoagulants?
Anticoagulants are drugs that interfere with the coagulation cascade. Heparin and warfarin are the two most well-known anticoagulants. These drugs may be used as prophylaxis to prevent deep vein thrombosis, embolism, and also to treat thromboembolism, myocardial infarctions, and peripheral vascular diseases. These drugs act by inhibiting vitamin K dependent clotting factors and by activating anti-thrombin III. Heparin is not available as a tablet while warfarin is.
Heparin and warfarin should be started together because warfarin increases blood coagulability for about three days and heparin provides the necessary protection against thromboembolic events. Warfarin increases INR and, therefore, INR is used as a method to monitor treatment. After atrial fibrillation INR should be kept between 2.5 to 3.5. Therefore, regular follow-up is essential.
What is the Difference Between Antiplatelet and Anticoagulant?
The key difference between antiplatelet and anticoagulant is that antiplatelet drugs block platelet plug formation while anticoagulants interfere with the extrinsic and intrinsic pathways. Antiplatelets usually may cause gastrointestinal bleeding due to increased acid secretion while anticoagulants may cause bleeding due to thrombocytopenia. Moreover, antiplatelet may be given while pregnant while warfarin, which is an anticoagulant, should not be.
The below infographic presents the differences between antiplatelet and anticoagulant in tabular form for side by side comparison.
Summary – Antiplatelet vs Anticoagulant
Antiplatelets and anticoagulants are drugs involved in the process of blood clotting. The key difference between antiplatelet and anticoagulant is that antiplatelet drugs block platelet plug formation while anticoagulants interfere with the extrinsic and intrinsic pathways.
1. “1909 Blood Clotting” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia
2. “Coagulation Cascade and Major Classes of Anticoagulants” By SteveKong3 – Own work (CC BY-SA 4.0) via Commons Wikimedia