DRUGS FOR COAGULATION DISORDERS Flashcards
homeostasis - injury to small vessels
- vessel spams, constricting the vessel and limiting blood flow to the site of injury
- platelets bind with high affinity to the damaged vessel. Activated platelets release adenosine diphosphate (ADP) and thromboxane A2 which stimulate the activation of new platelets, platelet aggregation and vasoconstriction
- thrombin is also produced. thrombin converts fibrinogen into fibrin. fibrin strands provide the scaffolding that forms the clot.
extrinsic pathway
triggered when tissue thromboplastin is released from damaged cells (outside the circulation)
- catalyzes formation of factor Xa
intrinsic pathway
triggered when collagen is exposed at the site of vascular injury to the blood components
- catalyzes formation of factor Xa
common pathway
synthesis of factor Xa
what is fibrinolysis?
- dissolving the clot
- is initiated 24 to 48 hours after clot formation
- cells adjacent to the clot
- PLASMIN: digests fibrin and destroys the clot
thromboembolic disorders
- formation of non therapeutic clots
- occlusion of arterial vessels leads to the MI an CVA
- embolus (ie. travelling clot)
- piece of stable thrombi breaks off and lodges in smaller blood vessels
bleeding disorders
(less important)
- thrombocytopenia (bone marrow suppression)
- low platelet count
- hemophilia
what drug classes are for prevention of clot formation?
anticoagulant, anti platelet
what drug class is for removal of an existing clot?
thrombolytic
what drug class is for inhibition of the destruction of fibrin?
antifibrinolytic
what are anticoagulant drugs?
- modulate coagulation cascade and thrombin formation
- lengthen clotting times and prevent thrombi from forming (or growing larger) in veins and arteries
- in cases of MI or CVA, administered IV or SC for rapid onset of action
in cases of MI or CVA, how should anticoagulants be administered?
administered IV or SC for rapid onset of action
once disease (MI or CVA) has stabilized, how should anticoagulant drugs be administered?
oral or SC
what is heparin?
(IV, SC)
- found in liver and lining of blood vessels
- catalyzes the inactivation of thrombin
- enhances the ability of antithrombin III to inactivate thrombin and clotting factor Xa
- thrombin no longer available to convert fibrinogen to fibrin
- inhibition of factor Xa, inhibits intrinsic and extrinsic pathways of the clotting cascade
- protamine sulphate
what is heparin used to prevent?
venous thrombosis, pulmonary embolism, disseminated intravascular coagulation (DIC), treatment in MI an stroke
- monitor for bleeding
