Pharmacology - VTE anticoagulants Flashcards by amanda kastel

briefly explain the mechanism of clot formation

vasoconstriction

platelet plug formation – platelets aggregate and stick together

clot formation - FIBRIN proteins stick together to form a CLOT

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briefly explain what is happening in deep vein thrombosis

clot forms in the legs

this can potentially form an embolus which travels to other areas of the body and can cause major issues

ie - pulmonary embolism

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3 risk factors for venous thromboembolism

-stasis (not moving)
-endothelial injury (ie - surgery, trauma)
-hypercoagulability

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____ use can potentially cause thromboembolism

estrogen

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there are intrinsic and extrinsic coagulation pathways.

which factor is common to both???

therefore, Xa inhibitors are very common anticoagulants!

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what causes coagulation factors to initiate coagulation?

when they come in contact with the endothelium — ie bc of injury

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name 3 things that can be blocked to treat deep vein thrombosis

fibrinogen
Xa
prothrombin

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unfractionated heparin is also called…

high MW heparin

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name 4 LMWH’s

enoxaparin
dalteparin
tinzaparin
fondaparinux

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name 4 oral Xa inhibitors

rivaroxaban
apixaban
edoxaban
betrixaban

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name a thrombolytic

alteplase

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low molecular weight heparins are ____ ____ antagonists

parenteral Xa

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name 2 direct thrombin inhibitors

bivalirudin
argatroban

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name a vitamin K antagonist

warfarin

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explain the MOA of unfractionated heparin (high MW heparin)

it accelerates the formation of antithrombin III (our natural anticoagulant)-thrombin complex

this inactivates thrombin (IIa) (and inhibits its formation), as well as Xa, and prevents the conversion of fibrinogen to fibrin, and PREVENTS clot formation overall

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true or false

unfractionated heparin cannot be given in pregnancy

FALSE

it does not cross the placenta

it’s ok in pregnancy

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**major AE of high MW heparin (unfractionated)

THROMBOCYTOPENIA (low platelets)

called HIT (heparin-induced thrombocytopenia)

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what does heparin do to aPTT time

increases it

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name 2 monitoring parameters for heparin (unfractionated)

bleeding
APTT

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heparin (unfractionated) contraindication

any bleeding issue

ie - another anticoagulant

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name 4 types of drugs that antagonize anticoagulation and thus can cause a clot when administered with heparin

nicotine
cardiac glycosides
antihistamines
tetracyclines

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thrombosis meaning

clot

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3 major advantages of high MW heparin

continuous IV drip - accurate dosing

rapid onset and short duration

monitoring APTT can help to determine if it’s working as it should

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low molecular weight heparins are said to have higher ___ activity than ____

higher inhibition of Xa than IIa (THROMBIN)

like a 4:1 ratio

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true or false low molecular weight heparins have a lower incidence of thrombocytopenia than unfractionated heparin

true

true or false LMWH has focused action against IIa

FALSE - against Xa not as much to thrombin

prototype for low MW heparins

enoxaparin

how is enoxaparin administered

subq injection

2 AE of enoxaparin

hemorrhage, thrombocytopenia

name some drugs that have a DDI concern with enoxaparin and have a bleeding concern

other anticoagulants, antiplatelets, NSAIDS

how often is enoxaparin administered****

Q12 for DVT treatment and QD for prophylaxis

***do labs need to be monitored for LMWH's like enoxaparin

*****true or false low molecular weight heparins have a lower incidence of HAT

true this is the non-immune-mediated thrombocytopenia

*****LMWH's are administered subq how is this an advantage?

dont need a hospital IV - reduced expenses can administer at home to prevent DVT during the 9 months of pregnancy

what is the QD dosing for LMWH's

1mg/kg

****what is the name of the heparin antagonist? what is it used for?

protamine sulfate to back titrate an over dose of heparin (high MW)

what is a big caution when giving protamine sulfate

it releases histamine! this can lower BP potentially too much and cause shock therefore, infuse SLOWLY over 10 mins

****big problem with high molecular weight IV heparin

HIT - heparin induced thrombocytopenia

what are the findings when a patient gets HIT is it immune mediated?

yes immune mediated skin is bruised, red, itchy platelets reduced to 50%

HAT

heparin ASSOCIATED thrombocytopenia (type 1 )

difference in platelet count between HIT and HAT

HIT - below 100,000 HAT - they rarely even go below 150,000

***which drugs can be used in a patient that needs anticoagulation therapy but HAS HIT????

targeted Xa and IIa inhibitors: fondaparinux (Xa) hirudin, Bivalirudin, Argatroban, Melagatran (IIa)

**name 1 subQ Xa inhibitor and 4 PO Xa inhibitors

subq - fondaparinux PO - rivaraxoban, apixaban, edoxaban, betrixaban

explain the MOA of fondaparinux

selectively inhibits factor Xa does this indirectly through binding ATIII. this causes ATIII to change shape and this increased affinity for Xa to neutralize it more this neutralization of Xa interrupts the blood coagulation cascade --- inhibits thrombin formation and clot development

common and severe SE of fondaparinux

bleeding, bruising

can LMWHs be used in HIT patients

NO there is cross reactivity with the antibodies

fondaparinux can be used as prophylaxis of DVT?

yes - after major orthopedic and abdominal sirgeries

factor Xa is required in the clotting cascade to do what?

cleave prothrombin into THROMBIN

Is there a DDI concern with eliquis and xarelto?

YES 3a4 and p-glycoprotein inhibitors and inducers

*how to recognize the oral Xa inhibitors

"ban"

what class is edoxaban

an oral Xa inhibitor -- a NOAC

what class is betrixaban

an oral XA inhibitor (BAN)

how does betrixaban inhibit Xa

competitive and reversible

***which drugs can be used for the treatment of venous thromboembolism?

any anticoagulant

name 2 targeted IIa (thrombin) inhibitors how are they each administered

bivalirudin - IV dabigatran - PO

****what are the 3 classes of thrombin inhibitors? **name each drug in the class

indirect (univalent), bivalent (direct), univalent (direct) bivalent means they bind at 2 sites indirect - heparin direct bivalent - bivalirudin, lepirudin, desirudin univalent direct - argatroban, ximelagatran, dabigatran

side effects bivalirudin as a recap, what class is it?

hemorrhage, hypotension a direct thrombin inhibitor (bivalent)

true or false dabigatran is an oral IIa inhibitor

TRUE

what are the advantages of dabigatran over warfain what's a disadvantage of it

no dietary, DDI, and monitoring problems (INR) bleeding

true or false dabigatran is a prodrug

TRUE

dabigatran is a direct thrombin inhibitor is it noncompetitive or competitive

competitive

main AEs of dabigatran

bleeding - 17%!!!! dyspepsia and GI complaints - take with food!! no antacids!

a patient is having an issue with dyspepsia while on dabigatran how do u counsel

they can try an H2 blocker BUT it may decrease bioavailability bc acidic environment is needed for absorption

true or false dabigatran has no CYP DDIs

true BUT does have DDI with p-glycoprotein inducers/inhibitors

name 2 ORAL anticoagulants that permit hospital discharge

warfarin (need monitoring) dabigatran (do not need monitoring)

MOA warfarin

inhibits vitamin K formation - vitamin K antagonist does this by inhibiting vitamin K reductase and vitamin K epoxide reductase this inhibits a lot of things -- the functional form of a lot of factos, as well as proteins C,S, and Z

true or false warfarin does NOT dissolve a preexisting clot

TRU

true or false warfarin is not very protein bound

FALSE - it is 97-99%

can warfarin be used in pregnancy

NO crosses BBB

polymorphisms in ___ and ____ affect the response to warfarin explain how they affect it

CYP2C9 and CKOR (vitamin K epoxide reductase) CYP2C9 will significantly inactive (s)-warfarin (the most potent form) warfarin works by inhibiting VKOR

endogenous role of vitamin K

causes clotting

what is the coumadin antagonist and thus the antidote for warfarin overdose

VITAMIN K

what is the antidote for dabigatran

idarucizumab (monoclonal antibody)

what is the name of the factor Xa inhibitor (eliquis, xarelto) reversal agent

annexa-A

Pharmacology - VTE anticoagulants Flashcards

(75 cards)