14 Questions
What is the main function of anticoagulants?
Prevent thrombosis
Which type of drug inhibits platelet activation or aggregation?
Heparin derivatives
What is the mechanism of action of coumarin anticoagulants?
Blocking multiple steps in the coagulation cascade
Which type of antithrombotic drug degrades fibrin?
Fibrinolytic agents
What is the role of direct oral anticoagulants?
Inhibit factor Xa or thrombin
Which factor is also known as Thromboplastin or Tissue factor?
Factor III (Thromboplastin or Tissue factor)
What is the main risk associated with all antithrombotic drugs?
Hemorrhage
What substance is formed from the injured tissues and initiates the extrinsic pathway of blood clotting?
Factor III (Thromboplastin or Tissue factor)
In the intrinsic pathway of blood clotting, which factor activates factor X in the presence of factor VIII and calcium?
Factor IX (Christmas factor)
What converts prothrombin into thrombin in the first stage of blood clotting?
Factor II (Prothrombin)
What is the substance that converts factor XII into factor XIIa in the intrinsic pathway?
Kallikrein
What is the factor that activates factor XI to factor XIa in the presence of HMW kinogen in the intrinsic pathway?
Factor XII (Hageman factor or Contact factor)
What is the substance that forms prothrombin activator when it reacts with platelet phospholipid and factor V in the presence of calcium ions?
"Factor Xa"
What is activated by the positive feedback effect of thrombin?
"Factor V (Labile factor or Proaccelerin or accelerator globulin)"
Study Notes
- Blood must maintain a balance between coagulation and fibrinolysis to prevent thrombosis and hemorrhage. Imbalance results in thrombi formation in arteries or veins.
- Antithrombotic drugs include antiplatelet drugs, anticoagulants, and fibrinolytic agents.
- Heparin and its derivatives are parenteral anticoagulants that activate antithrombin, inhibiting coagulant proteases.
- Coumarin anticoagulants block multiple steps in the coagulation cascade.
- Direct oral anticoagulants inhibit factor Xa or thrombin.
- Antiplatelet agents include aspirin, clopidogrel, prasugrel, ticagrelor, and vorapaxar. They inhibit platelet activation or aggregation.
- Fibrinolytic agents degrade fibrin.
- Blood coagulation or clotting is the process in which blood loses fluidity and becomes a solid mass.
- Factors involved in blood clotting include Factor I (fibrinogen), Factor II (prothrombin), Factor III (thromboplastin or tissue factor), Factor IV (calcium), Factor V, Factor VI, Factor VII, Factor VIII, Factor IX, Factor X, Factor XI, Factor XII, and Factor XIII.
- Blood clotting stages include the formation of prothrombin activator, conversion of prothrombin into thrombin, and conversion of fibrinogen into fibrin.
- Prothrombin activator formation occurs through intrinsic and extrinsic pathways.
- Intrinsic pathway: Initiated by platelets, which release phospholipids and activate factors in the presence of calcium.
- Extrinsic pathway: Initiated by tissue thromboplastin, formed from damaged tissues, and calcium.
Explore the fundamental concepts of anticoagulants in pharmacology, including the delicate balance between coagulation and fibrinolysis. Learn about the mechanisms that regulate blood fluidity and clotting, as well as the implications of alterations in this balance.
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