anticoagulants Flashcards
What is a thrombosis
a normal response to hemorrhage when a blood clot forms in the vascular system
what can thrombosis lead to
PE, Stroke, MI
signs of PE?
dyspnea, tachycardia, (massive = dyspnea, syncope, HOTN, cyanosis) (small = pleuritic pain, cough, hemoptysis)
what is virchow’s triad?
hypercoagulability, stasis, endothelial injury
what can help prevent DVT?
ambulation, compression stockings, anticoagulants
risk factors for developing PE
CHD, stroke, paralysis
name the indirect thombin inhibitors
heparin, Lovenox, Fondaparinux
Where is most heparin derived from?
pigs
MOA of indirect thrombin inhibitors?
conformational change binds antithrombin, inactivates factor Xa and thrombin (II)
what factor is most closely related to bleeding risk?
focus on factor Xa
what should the CrCl be above to use direct thrombin inhibitors?
30%
What indirect thrombin inhibitor can be used in pregnancy?
Lovenox
which indirect thrombin inhibitor does not require close monitoring
enoxaparin, fondaparinux
half life of heparin?
1-5 hours
half life of lovenox?
4-6 hours
half life of fondaparinux?
17 hours
how are indirect thrombin inhibitors monitored?
aPTT, anti-factor Xa levels
reversal agent for heparin?
protamine sulfate
what is HIT?
heparin induced thrombocytopenia, drop in platelets 5-10 days after exposure (150k-200k)
What is HITT?
heparin induced thrombocytopenia with thrombosis - Ab against heparin/platelet factor 4 results in platelet activation
Can patients with HITT use heparin again?
NO
what labs should be ordered for baseline before starting heparin therapy?
platelets
What are the oral factor Xa inhibitors
rivaroxaban, apixaban
how are oral direct factor Xa inhibitors different from warfarin?
shorter half-lives
Which direct factor Xa inhibitor can be used prophylactically with sx?
Rivaroxaban
What oral direct factor Xa inhibitor can reduce stroke risk in nonvalvular Afib?
Apixaban
how are direct factor Xa inhibitors excreted?
renally, dose adjust for renal impairment
How are direct factor Xa inhibitors metabolized?
CYP3A4, p-glycoprotein
ADR of direct factor Xa inhibitors
peripheral edema, dizziness, HA, diarrhea, bleeding
what factor does rivaroxaban work on?
factor Va
what factor do oral direct thrombin inhibitors work on?
factor Iia
Name the oral direct thrombin inhibitor
Dabigatran (pradaxa)
MOA of dabigatran
sits on exosite 1 of thrombin
uses for dabigatran?
prevention of stroke and systemic embolism in pts with nonvalvular Afib
Do bleeding rates differ between dabigatran and warfarin?
no
when does dabigatran need to be dose adjusted?
renal impairment - 75mg
ADR of dabigatran
bleeding, dyspepsia, gastritis-like sxs, GI hemorrhage
what can be used as an anti-coagulant in HIT/HITT?
argatroban
what lab is used to monitor direct/indirect thrombin inhibitors?
aPTT (should be 1.5-3x the normal)
how do oral antiplatelets work?
bind to ADP and downregulate Iib/IIIa which decreases platelet sticking to each other
name the oral antiplatelets
ticlid, plavix, effient, brillinta
what metabolizes clopidogrel?
2C19 (2 step reaction)
how is brillinta metabolised and dosed?
it is an active drug (faster onset) and needs to be taken twice a day
what drug can decrease clopidogrel efficacy?
nexium, PPIs
what causes clopidogrel resistance?
genetic basis that increases CYP2C19
according to the CHARISMA study, do oral antiplatelets decrease risk of death?
nope
ADR for antiplatelets
bleeding, rash, pruritis, GI hemorrhage, TTP
how soon does clopidogrel begin to work?
10-11 days
why is ticlid not used?
BID, life-threatening hematologic reactions
Which oral antiplatelet is weight-based?
effient
Who should not use effient?
>75 y/o, <60kg
uses for oral antiplatelets
recent MI, stroke prevention
what oral antiplatelet is used for prophylactic treatment with a stent for 1 year?
clopidogrel
Name a vitamin K antagonist
warfarin
what does warfarin have no effect on?
fully carboxylated molecules (anticoagulants)
how long does it take for warfarin to work?
3-5 days
What is the protein C phenomenon?
reduced levels with warfarin
What does warfarin bind to?
albumin
Target INR
2 through 3
How many INRs need to be above 2 to be stabilized on warfarin?
2
what drugs increase warfarin effect?
amiodarone, ginkgo, omeprazole
what drugs decrease warfarin effect?
estrogens, protease inhibitors, st john’s wart
reversal agent for warfarin
phytonadione (vitamin K)
