clotting cascade and drugs Flashcards
arterial thrombus
white thrombus: platelets in fibrin mesh
arterial thrombus treatment
antiplatelet
venous thrombus
red thrombus
venous thrombus Treatment
anticoagulants
what does the extrinsic pathway start with
TF
what does the intrinsic pathway start with
XII
what converts prothrombin to thrombin
Xa
what converts fibrinogen to fibrin
thrombin
what converts plasminogen to plasmin
tPA
what is warfarin structure similar to
vitamin K
warfarin action
blocks vit K dependent gamma carboxylation of glutamate residues
results in the production modified factors VII, IX, X and prothrombin (factor II)
what is used to monitor warfarin dosage
prothrombin time
how long does warfarins full effect take
4-5 days
what must you do with warfarin if you require an immediate effect
use heparin
warfarin therapeutic index
low
factors that potentiate warfarin (inc risk of haemorrhage)
liver disease
high metabolic rate
factors that lessen warfarin action (risk of thrombosis inc)
pregnancy or hypothyroidism
vitamin K consumption
warfarin overdose
stop drug and give vitamin K (oral phytomenadione)
heparin action
activates antithrombin III
what does antithrombin III do
inhibit thrombin, factor Xa and IXa/tenase
LMWH action
inhibits Xa
LMWH example
dalteparin
LMWH half life in comparison to heparin
longer
LMWH dosage
daily dose by SC injection
eliminate of heparin order
0
eliminate of LMWH order
1
why is heparin preferred in renal failure to LMWH
LMWH is excreted via the renal system
what inactivates heparin e.g. in event of haemorrgae
sulphate IV
rare adverse effect of heparin
osteoporosis
dabigataran etexilate action
inhibit thrombin
rivaroxaban action
inhibit Xa
clopidogrel action
blocks P2Y receptors
tirofiban action
interfere with fibrongen binding to GPIIb/IIIa receptors on activated platelets.
what effect does the fibrinolytic cascade have on the coagulation cascade
opposes it
streptokinase action
cleaves plasminogen molecules to produce plasmin
what is streptokinase
streptococcus bacterial protein
who shouldn’t streptokinase be given to
patients with recent streptococcal infections
alteplase and dulteplase action
inc action of tPA
how is haemorrhage with fibrinolytic controlled
tranexamic acid