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Lex Clinical Pharm exam 1 > 13. Anticoagulants > Flashcards

13. Anticoagulants Flashcards

1
Q

anticoagulants

A

reduce the formation of thrombin

inhibit the activity of clotting factors

inhibit synthesis of clotting factors

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2
Q

unfractionated heparin MOA

A

MOA: enhance activity of antithrombin
inhibits factor 10a and thrombin equally
inhibits change of fibrinogen to fibrin

mixture of long polysaccharide chains

must bind to antithrombin to be activated before it can bind to thrombin

binds normally to factor 10a

must bind to antithrombin first then bind to thrombin to give it a big hug - long tails

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3
Q

heparin overview

A

indications: prevention of thrombosis
onset: minutes to hours

ROA: IV, SQ

metabolism: hepatic, then cleared by kidneys
dosing: bolus (loading)

adverse effects: bleedng, HIT, spinal/edpidural hematoma

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4
Q

heparin monitoring

A

aPTT (more common) or anti-Xa

checked every 4-6 hours

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5
Q

aPTT

A

activated partial thromboplastin time

measure time it takes for blood to clot

higher aPTT more anticoagulation effects - on heparin (anti-coag) it will take longer to clot and have a higher aPTT

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6
Q

Anti-Xa

A

meaures amount of 10a not bound by heparin

higher the level = more anti-coagulation effects

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7
Q

heparin-induced thrombocytopenia (HIT)

A

type 1 - 1-2 days after exposure = transient drop-in platelets, will recover

type 2- 4-7 days after exposure = 50% drop in platelets over time and worry about thrombosis

heparin has long tails and body recognizes it as foreign and immune complex created

body develops antibodies to heparin platelet factor 4 (PF4) complex - results in new thrombosis development

confirm by ordering HIT antibody test with SRA assay

treatment: discontinue heparin, initate argatroban

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8
Q

reversing bleeding with UFH (heparin)

A

not done for elevated aPTTs - 1/2 life is only 2 hours

antidote: Protamine

binds with heparin - neutralization is immediate. give plasma or blood

now heparin cannot bind to antithrombin

protamine- positively charged
heparin - negatively charged

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9
Q

LMWH

A

smaller polysaccharides - no long tails

given outpatient do not need monitoring

MOA: binds to antithrombin and inactivate factor 10a only - does not bind to thrombin

Indications: Treatment and prevention of thrombosis

onset: 1-2 hours

ROA: SQ

EX: enoxaparin (lovenox) tinzaparin (Innohep) and dalteparin (fragmin)

renally cleared - cannot use in patients with acute kidney injury or hemodialysis

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10
Q

Monitoring LMWH

A

anti-xa levels do not check aPTT

adverse events: bleeding (less than in UFH), spinal/epidural hematoma, thrombocytopenia - less likely to debvelop immune complex because it does not have long tails

treat reversal of bleeding: protamine - not as effective as heparin binds to 80% of LMWH, give plasma or blood

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11
Q

LMWH vs UFH

efficacy
hospitalization
routing monitoring
cost
self-administration
use in pts with HD or AKI
potential for casuing HIT
A

LMWH UFH

equal                 equal
no                       yes
no                       yes
more                   less
yes                     no
no                       yes
rare                     <3%
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12
Q

fondaparinux

A

binds only with antithrombin - only essential plysacharrides- no tails

MOA: inhibits factor 10a by binding antithrombin

ROA: SQ

Renally elimiated cannot use in AKI/hemodialysis

can be used in patients with history of HIT

adverse Bleeding similar to LMWH or UFH

NO ANTIDOTE - give blood or plasma and wait for it to degrade

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13
Q

vitmain K antagonist

A

warfarin (coumadin, jantoven)

treat and prevent thrombosis - bridge while recieving SQ or IV anticoagulants for active clots

MOA: inhibits clotting factor synthesis that require vitamin K

inhibits production of prothtombin (factor 2), 7, 9, 10 and protein C and S

2+7=9+1=10

clotting cascade does not proceed- takes time for clotting factors to naturally go away to sho effects of warfarin

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14
Q

warfarin monitoring

A

international normalized ratio (INR) - compare clotting time to normal person vs someone on warfarin N=1 warfarin = 2-3

prothimbin time (PT)

adverse effects: bleeding

treat with phytonadione (vitamin K) - takes 2-6 horus and 24 hours to see full effects

can give plasma or prothombin complex concentrate (PCC) or factor 7 (novpseven) - gives you back these factors that warfarin inhibits

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15
Q

warfrin interactions thst cause increase effect on INR

A

inhibit metabolism of warfrin - higher levels of warfin = more clotting factpors inhibited and higher INR = too must anticoagulants or warfrin on board

bactrim
amiodarone
cimeetdine
acetametophin
metronizaole
azole antifungals
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16
Q

warfrin interactions thst cause decrease effect on INR

A

induce metabolism of warfin = body chew throw warfrin faster

phenobarbital
rifampin
phenytoin
carbamazepine

17
Q

direct thrombin inhibitors

A

MOA: inhibit thrombin 2a to prevent conversion of fribrinogen to fibrin

dabigatran (PO)
argatroban (IV)
bivalirudin (IV)

18
Q

dabigatran (pradaxa)

A

direct thrombin inhibitor

Indication: prophylaxis for non-vavular afib, treatment for DVT/PE

Onset: rapid

renally eliminated

treat life threatening bleed with praxbind

antibody targeted twoards drug - sequesters dabgigatron so it cannot bind other factors

19
Q

argatroban

A

direct thrombin inhibitor

HIT treatment, cardiac catheritization

metabolized by liver

monitoring: aPTT - will artifically increase INR

adverse effects: bleeding, no antidote, give plama or blood

20
Q

Bivalirudin

A

direct thrombin inhibitor

indications: PCI with active or remote history of HIT

renally eleminated

monirting: aPTT

adverse events bleeding
no antidote, give blood or plasma

21
Q

direct 10a inhibitors

A

new drug replacing warfarin

no monitoring values - rapid onset - oral agents only

rivaroxaban
apixaban
endozaban
betrixaban

antidote : andexxa - HD does not remove drug

22
Q

andexxa

A

treatment for 10a inhibitors

different 10a molecule with more potent ability to bind

factor 10a inhibors will bind andexxa with higher affinity then andogenous 10a

Lex Clinical Pharm exam 1 (14 decks)

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