Coagulation Flashcards
List 4 main characteristics of ideal coagulants
Should require less monitoring.
Fixed dosing.
Oral administration is preferred. Predictable PK. Broad therapeutic window
Which factors are affected by which anticoagulants
Factor Xa, IIa - Low molecular weight heparins
Direct thrombin inhibitors - IIa
Direct Factor Xa inhibitors - Xa
Give the mechanism of action of heparin
Binds to inactive antithrombin III. Activation of AT-III, which binds to Factor Xa and binds to Thrombin and BLOCKS its effect.
What does aPTT stand for
Activated Partial Thromboplastin Time
List a major adverse effect of heparin use
Bleeding (Epistaxis, Haematuria, Vaginal Bleeding)
Mild transient thrombocytopenia
Give a stepwise approach of reversal of heparin effects
STOP heparin, Identify source of bleeding, administer protamine sulphate (antidote)
Closely monitor aPTT
List 3 examples of LMWH
Enoxaparin, Dalteparin, Fondaparinux
What is the effect of chain length on activity
The longer the chain length, the more likely the drug will inhibit both the thrombin and the factor Xa activity
What is Virchow’s triad of thrombosis
Venous stasis, Hypercoagulability, Blood vessel wall injury
What are signs and symptoms of DVT and PE
Unilateral, chest pain, dyspnea, hemoptysis, cyanosis
Catergorise bleeding disorders
Primary: Idiopathic thrombocytopaenia purpura
von Willebrand disease
Secondary: Haemophilia, Liver Disease, Vitamin K deficiency
3 signs of haemophilia
Ecchymosis, Haematomas, GIT bleeding
Describe the phases of haemostasis
There is cell injury, then Von Willebrand factor is expressed. Then there is the GPIIb/IIIa + Fibrinogen mesh, which leads to inital clot formation and primary clot formation. Then Fibrinogen forms into fibrin (From Factor XIIIa). From fibrin, a stable clot is formed and then there is clot stabilisation
Describe the process of platelet plug formation.
1) Vasospasm. 2) Platelet adhesion 3) Platelet activation. 4) Platelet aggregation.
What is the function of ADP in platelet plug formation?
ADP binds to P2Y12 receptors on the platelet. This increases intracellular Calcium, which increases expression of GP2B3A receptors and increases Thromboxane A2 production.
