Anticoagulants Flashcards
CCM 3rd Edt
Chapter 165 - Anticoagulants
`In health how is thrombosis inhibited?
endothelial cell surface is itself antithrombotic and inhibits platelet attachment through its negatively charged surface
Tissue factor pathway inhibitor (TFPI) is localized to the endothelial cell surface
the glycocalyx anchors heparan sulfate, - promotes the anticoagulant activity of antithrombin (AT). AT inhibits thrombin, factor Xa (FXa), and factor IXa (FIXa).
Protein C is also an endogenous inhibitor of coagulation. Activated protein C is generated when thrombin binds thrombomodulin on the endothelial surface.
is warfarin reccomended in veterinary patients?
No
How does warfarin work?
Inhibits Vit K epoxide reductase –> 2,7, 9, 10
reduces vit k recycling to therefore have less vit k available for gamma carboxylation
How do heparins result in anticoagulation?
potentiating the activity of AT through allosteric modification
he fractions of higher molecular weight heparin form a large ternary complex with AT that inactivates FIIa and FXa, with a ratio of 1:1 for anti-Xa to anti-IIa activity. Once bound to AT, UFH inhibits FIXa, FXa, FXIa, FXIIa, and FIIa, with its most profound effects on FIIa and FXa.
How is heparin reversed?
protamine sulfate
How are LMW heparins different?
he lower molecular weight heparin molecules are not able to bind both AT and FIIa as required for FIIa inhibition but are able to potentiate the affinity of AT for FXa and have a 4:1 ratio of anti-Xa to anti-IIa activity
can protamine be used to reverse LMWH
only some of the anticoagulant action of the LMWHs because anti-Xa activity is not completely neutralized
What is the usual aptt goal of heparin therapy
1.5 to 2.0 times the normal or baseline value.
however ideally antiXa levels are used
how does rivaroxaban work?
FXa inhibitor - oral
