coagulation Flashcards
hemostasis (arrest of bleeding) is achieved in what three ways
- vascular contraction (vasospasm)
- platelet adhesion, activation, and aggregation
- fibrin formation and reinforcement of the platelet plug
What is a factor that is produced from endothelial cells and inhibits platelet adhesion
PGI2
- Prostacyclin (also called prostaglandin I2)
What factor in platelets binds to fibronogen in blood stream
GPIIb/IIIa
What are the three functions of thrombin
- positive feedback on intrinsic pathway
- activate platelets
- catalyze conversion of fibrinogen to fibrin
What factors are part of the intrinsic pathway
8, 9, 11, 12
What factors are part of the extrinsic pathway
- tissue factor
- VII
Damage to the blood vessel endothelium causes release of
von Willebrand factor (vWF)
Binding of platelets to collagen (through glycoprotein 1a (GP 1a)) and vWF (through GP 1b) activates the bound platelets to release
ADP, thromboxane A2 (TXA2), and serotonin (5-HT)
What are three natural inhibitors of coagulation in the body
- Antithrombin III
- Tissue factor pathway inhibitor (TFPI) – blocks the activity of TF/VIIa
- Protein C – with its cofactor, protein S, destroys factors Va and VIIIa
PTT evaluates which pathway
intrinsic
PT and INR evaluate which pathway
extrinsic pathway
PTT monitors action of which drug
Heparin
INR (PT) monitors action of which drug
warfarin
list the High-molecular weight heparins
Heparin sodium (Liquaemin®)
List the Low molecular weight heparins
- Enoxaparin (Lovenox®)
- Fondaparinux (Arixtra®): synthetic pentasaccharide
List the Direct thrombin inhibitors
- Lepirudin (Refludan®)
- Argatroban (Novastan®)
- Dabigatran (Pradaxa®)
List the Direct inhibitors of factor Xa
- Rivaroxaban (Xarelto®)
- Apixaban (Eliquis®)
- Edoxaban
What is Heparin
a heterogenous mix of sulfated mucopolysaccharies; action from a unique pentasaccharide
MOA of Heparin
- accelerates Antithrombin III activity
- mainly affects Xa and thrombin
- is recycled and stays active after releasing from inactivated clotting factor
When is heparin used
- anticoagulant -> operations and IV catheters
- prophylaxis against thrombosis (DVT and PE)
route of administration of heparin
IV only, onset of action is immediate
adverse effects of heparin
- hemorrhage
- heparin induced thrombocytopenia (HIT)