18/19 - Antithrombotic Agents Flashcards
MOA aspirin
irreversibly block COx1 in platelets which reduces TXA2 production
MOA dipyridamole
elevates cAMP levels which reduce Ca2+ levels which reduces activation of platelets
P2Y12 antagonists
clopidogrel and prasugrel irreversibly inhibit P2Y12
ticagrelor and cangrelor are reversible
contraindication for clopidogrel
omeprazole use
what enzyme activates clopidogrel?
CYP2C19
which P2Y12 antagonists would you use for a patient with intracranial bleeding?
clopidogrel or cangrelor
NOT prasugrel or ticagrelor they have higher bleeding rates but better results
GP IIb and IIIa antagonists
abciximab
eptifibatide
tirofiban
highest risk GPIIb/IIIa antagonist
abciximab
monoclonal antibdoy directed against the GP but also antiinflammatory
MOA vorapaxar
protease activated receptor antagonist
dual antiplatelet therapy
aspirin and P2Y12 antagonist
triple antiplatelet therapy
warfarin
aspirin
clopidogrel
MOA of heparin
accelerates rate of factor Xa inhibition
(only loner heparin molecules) also increases AT induced inhibition of thrombin
for heparin…. clearance ______ as dose increases
decreases
dose-dependent clearance
t1/2 __– as dose increases for heparin
increases
what system is used to monitor heparin
partial thromboplastin time PTT
if bleeding is severe with heparin, what can be administered
protamine sulfate
risk of long term heparin use
osteoporosis
type I v. type II heparin induced thombocytopenia
type 1- of little clinial consequence, first 2-5 days
type 2: immune thrombocytopenia with antibodies generated towards PF4/heparin complex —> venous and arterial thrombosis
more common in women and surgical pts
more common with unfractionated heparin
low molecular weight heparin =
enoxaparin
contraindications for enoxaparin and fondaprinux
renal insufficiency
heparin v. enoxaparin
enoxaparin - lower risk and better dosing with longer half-life
protamine only partially reverses enoxaparin
MOA fondaparinux
inhibits factor Xa
what is used to monitor enoxaparin and fondaprinux
anti-factor Xa assay
bind at both the fibrin binding site and the active site of thrombin
bivalirudin and lepirudin
bind only to the active site of thrombin
argatroban and dabigatran
only oral direct thrombin inhibitor
dabigatran
direct thrombin inhibitors versus heparin
both can inhibit soluble thrombin
DTIs can inhibit thrombin bound to fibrin
major drawback to direct thrombin inhibitors
specific antidotes do not exist
why is warfarin useful for longterm management
orally active
MOA warfarin
vitamin K antagonist at vitamin K reductase
vitamin K dependent factors
II
VII
IX
X
warfarin dosing
takes 3-5 days to reach full antithrombotic effect with long half life
what enzyme metabolizes warfarin
CYP2C9
what method is used to monitor warfarin
prothrombin time is generally used
target INR for warfarin
2-3
the effect of warfarin is _______ with
- antibiotics
- NSAIDs
- 5-HT reuptake inhbitors
- statins
increased
the effects of warfarin are _________ with
- rfampin
- barbiturates
- carbamazepine
decreased
because they all increase hepatic metabolism
decreased hepatic functionwith liver disease can __ the clearance of warfarin and __– INR
decrease
increase
diseases of the intestine such as crohn disease that reduce vitamin k absorption ______- the INR of warfarin
increase
hypoalbuminemia will have what effect on warfarin
increase INR
what causes necrosis with warfarin
fall in prtn C
direct Xa inhibitors
rivaroxaban
apixaban
which is better direct Xa inhibitors or warfarin
direct Xa inhibitors
aka oral anticoagulants
what is dabigatran contraindicated for>
mechanical heart valves
use warfarin instead
can you take warfarin during pregnancy?
no
but you can take heparin and heparin like drugs
what is needed for fibrinolysis?
tPA and plasminogen
what is the role of urokinase plasminogen activator
converts plasminogen into plasmin
recombinant human t-Pa
alteplase
modified recombinant human t-PA
reteplase
STEMI
tissue plasminogen activators used
not used for NSTEMIs or over 75 or past 12 hrs
block interaction of plasmin with fibrin
aminocaproic acid and tranexamic acid
used to treat hemophilia and reverse fibrinolytic bleeding
