antithrombotic therapies

Question 1

3 groups of antithrombotic therapy

Answer 1

-original drugs like heparin, coumadin, and aspirin
-drugs entered clinical use like heparin derivatives
-newest drugs which are direct-acting oral and intravenous anticoad

Question 2

venous thromboembolism (VTE) includes

Answer 2

superficial and deep vein thrombosis
pulmonary embolism

Question 3

therapy for VTE

Answer 3

IV standard UFH (unfractionated heparin)
-low molecular weight heparin
-DOAC
-oral vitamin K antagonist-coumadin

Question 4

ALL arterial thrombosis treated with

Answer 4

blah blah
-many people take aspirin to reduce mortality when taken within minutes of acute onset of stroke or cardiac symptoms

Question 5

fibrinolytics or thrombolytic therapy used to resolve

Answer 5

DVT
PE
PAO
AMI
Stroke

these drugs are recombinant forms of tissue plasminogen activator

Question 6

dosage of drugs depends if given

Answer 6

prophylactically (lower dose)
established thrombotic issue (higher dose)

Question 7

why are antithrombotics dangerous

Answer 7

effective dose range narrow
-must be monitored regularly

Question 8

what is coumadin

Answer 8

vitamin K antagonist
-suppresses gamma-carboxylation of glutamic acid by slowing activity of vitamin K epoxide reductase

Question 9

uses of coumadin

Answer 9

-prophylactically or as therapy
-prevent TIAs and stroke in pts with non-valvular A-fib
-prevent VTE after trauma
-prevent DVT and PE
-given after AMI
-mechanical heart valves

Question 10

how long does coumadin take to reach therapeutic level

Answer 10

5 days

Question 11

since protein C is vit K dependent and it has 6 hr half-life

Answer 11

activity decreases and for first 2-3 days of therapy pts at risk for thrombosis

UFH, LFWH given for 5 days to cover this

Question 12

issues with coumadin therapy

Answer 12

1- crosses the placenta
2-excreted in breast milk
3- needs monthly monitoring

Question 13

INR

Answer 13

international normalized ratio

-first sample is collected and performed 24 hrs after coumadin therapy is initiated

Question 14

INR =

Answer 14

Pt(patient) / PT (normal) ^Is1

-closer the ISI to 1 the better it is

Question 15

routine prophylaxis INR range

Answer 15

2-3

Question 16

INR range with prosthetic heart valve

Answer 16

2.5-3.5

Question 17

action of heparin

Answer 17

treats venous thrombosis

-mixture of sulfated glycosaminoglycans extracted from porcine mucosa which potentiates the action of anti-thrombin by 1000x

Question 18

heparin is metabolized by the liver half life

Answer 18

60-90 min

Question 19

APTT is commonly used but the

Answer 19

chromogenic anti-Xa heparin assay also used

Question 20

APTT reference range

Answer 20

old method: 1.5-2.5 x patient’s baseline
current method: ex vivo or brill-edwards method

Question 21

establishing reference range for UFH

Answer 21

20-30 plasma samples are collected from patients being infused with UFH at all levels of anticoag

pt can’t be on coumadin

Question 22

APTT is checked after 4-6 hours from the start of therapy this result should

Answer 22

fall in therapeutic range adjustments are made and APTT checked every 24 hrs and dose is continuously adjusted

Question 23

indication of HIT

Answer 23

> 40% reduction in plt count

Question 24

heparin can be reversed immediately by giving pt

Answer 24

protamine sulfate

Question 25

low molecular weight heparin therapy action

Answer 25

same as heparin, however thrombin neutralization response is reduced ; LMWH still has same efficacy as UFH because factor Xa neutralization response is unchanged

Question 26

half life of LMWH

Answer 26

3-5 hrs -safer than UFH

Question 27

lab monitoring for LMWH

Answer 27

must use chromogenic anti-Xa heparin assay monitoring is not necessary unless pt is pregnant, pediatric, over/under weight or renal disease

Question 28

synthetic form of active pentasaccharide sequence in UFH and LMWH

Answer 28

fondaparinux -only synthetic heparin

Question 29

fondaparinux inhibits

Answer 29

only factor xa through anti-thrombin

Question 30

half life of fondaparinux

Answer 30

17-21 hours given subcutaneous injection of 2.5-7.5 mg

Question 31

target range for fondaparinux

Answer 31

0.2-0.4 mg for 2.5 mg dose 0.5-1.5 mg/mL for 7.5 mg dose

Question 32

____ is not sensitive to the effects of fondaparinux

Answer 32

APTT

Question 33

direct oral anticoag that inhibit Xa

Answer 33

rivaroxaban apixaban edoxaban betrixaban -don't require antithrombin to inhibit coag

Question 34

direct thrombin inhibitors

Answer 34

oral dabigatran -no anti-thrombin needed to work -cleared by kidney and half life 10-18 hrs

Question 35

aspirin irreversibly acetylates

Answer 35

platelet enzyme COX -this hinders the access of arachidonic acid, which prevents production of platelet activating TXA2